LCOV - code coverage report
Current view: top level - kernel/sched - core.c (source / functions) Hit Total Coverage
Test: landlock.info Lines: 1364 2281 59.8 %
Date: 2021-04-22 12:43:58 Functions: 130 204 63.7 %

          Line data    Source code
       1             : // SPDX-License-Identifier: GPL-2.0-only
       2             : /*
       3             :  *  kernel/sched/core.c
       4             :  *
       5             :  *  Core kernel scheduler code and related syscalls
       6             :  *
       7             :  *  Copyright (C) 1991-2002  Linus Torvalds
       8             :  */
       9             : #define CREATE_TRACE_POINTS
      10             : #include <trace/events/sched.h>
      11             : #undef CREATE_TRACE_POINTS
      12             : 
      13             : #include "sched.h"
      14             : 
      15             : #include <linux/nospec.h>
      16             : 
      17             : #include <linux/kcov.h>
      18             : #include <linux/scs.h>
      19             : 
      20             : #include <asm/switch_to.h>
      21             : #include <asm/tlb.h>
      22             : 
      23             : #include "../workqueue_internal.h"
      24             : #include "../../fs/io-wq.h"
      25             : #include "../smpboot.h"
      26             : 
      27             : #include "pelt.h"
      28             : #include "smp.h"
      29             : 
      30             : /*
      31             :  * Export tracepoints that act as a bare tracehook (ie: have no trace event
      32             :  * associated with them) to allow external modules to probe them.
      33             :  */
      34             : EXPORT_TRACEPOINT_SYMBOL_GPL(pelt_cfs_tp);
      35             : EXPORT_TRACEPOINT_SYMBOL_GPL(pelt_rt_tp);
      36             : EXPORT_TRACEPOINT_SYMBOL_GPL(pelt_dl_tp);
      37             : EXPORT_TRACEPOINT_SYMBOL_GPL(pelt_irq_tp);
      38             : EXPORT_TRACEPOINT_SYMBOL_GPL(pelt_se_tp);
      39             : EXPORT_TRACEPOINT_SYMBOL_GPL(sched_cpu_capacity_tp);
      40             : EXPORT_TRACEPOINT_SYMBOL_GPL(sched_overutilized_tp);
      41             : EXPORT_TRACEPOINT_SYMBOL_GPL(sched_util_est_cfs_tp);
      42             : EXPORT_TRACEPOINT_SYMBOL_GPL(sched_util_est_se_tp);
      43             : EXPORT_TRACEPOINT_SYMBOL_GPL(sched_update_nr_running_tp);
      44             : 
      45             : DEFINE_PER_CPU_SHARED_ALIGNED(struct rq, runqueues);
      46             : 
      47             : #ifdef CONFIG_SCHED_DEBUG
      48             : /*
      49             :  * Debugging: various feature bits
      50             :  *
      51             :  * If SCHED_DEBUG is disabled, each compilation unit has its own copy of
      52             :  * sysctl_sched_features, defined in sched.h, to allow constants propagation
      53             :  * at compile time and compiler optimization based on features default.
      54             :  */
      55             : #define SCHED_FEAT(name, enabled)       \
      56             :         (1UL << __SCHED_FEAT_##name) * enabled |
      57             : const_debug unsigned int sysctl_sched_features =
      58             : #include "features.h"
      59             :         0;
      60             : #undef SCHED_FEAT
      61             : #endif
      62             : 
      63             : /*
      64             :  * Number of tasks to iterate in a single balance run.
      65             :  * Limited because this is done with IRQs disabled.
      66             :  */
      67             : const_debug unsigned int sysctl_sched_nr_migrate = 32;
      68             : 
      69             : /*
      70             :  * period over which we measure -rt task CPU usage in us.
      71             :  * default: 1s
      72             :  */
      73             : unsigned int sysctl_sched_rt_period = 1000000;
      74             : 
      75             : __read_mostly int scheduler_running;
      76             : 
      77             : /*
      78             :  * part of the period that we allow rt tasks to run in us.
      79             :  * default: 0.95s
      80             :  */
      81             : int sysctl_sched_rt_runtime = 950000;
      82             : 
      83             : 
      84             : /*
      85             :  * Serialization rules:
      86             :  *
      87             :  * Lock order:
      88             :  *
      89             :  *   p->pi_lock
      90             :  *     rq->lock
      91             :  *       hrtimer_cpu_base->lock (hrtimer_start() for bandwidth controls)
      92             :  *
      93             :  *  rq1->lock
      94             :  *    rq2->lock  where: rq1 < rq2
      95             :  *
      96             :  * Regular state:
      97             :  *
      98             :  * Normal scheduling state is serialized by rq->lock. __schedule() takes the
      99             :  * local CPU's rq->lock, it optionally removes the task from the runqueue and
     100             :  * always looks at the local rq data structures to find the most eligible task
     101             :  * to run next.
     102             :  *
     103             :  * Task enqueue is also under rq->lock, possibly taken from another CPU.
     104             :  * Wakeups from another LLC domain might use an IPI to transfer the enqueue to
     105             :  * the local CPU to avoid bouncing the runqueue state around [ see
     106             :  * ttwu_queue_wakelist() ]
     107             :  *
     108             :  * Task wakeup, specifically wakeups that involve migration, are horribly
     109             :  * complicated to avoid having to take two rq->locks.
     110             :  *
     111             :  * Special state:
     112             :  *
     113             :  * System-calls and anything external will use task_rq_lock() which acquires
     114             :  * both p->pi_lock and rq->lock. As a consequence the state they change is
     115             :  * stable while holding either lock:
     116             :  *
     117             :  *  - sched_setaffinity()/
     118             :  *    set_cpus_allowed_ptr():   p->cpus_ptr, p->nr_cpus_allowed
     119             :  *  - set_user_nice():          p->se.load, p->*prio
     120             :  *  - __sched_setscheduler():   p->sched_class, p->policy, p->*prio,
     121             :  *                              p->se.load, p->rt_priority,
     122             :  *                              p->dl.dl_{runtime, deadline, period, flags, bw, density}
     123             :  *  - sched_setnuma():          p->numa_preferred_nid
     124             :  *  - sched_move_task()/
     125             :  *    cpu_cgroup_fork():        p->sched_task_group
     126             :  *  - uclamp_update_active()    p->uclamp*
     127             :  *
     128             :  * p->state <- TASK_*:
     129             :  *
     130             :  *   is changed locklessly using set_current_state(), __set_current_state() or
     131             :  *   set_special_state(), see their respective comments, or by
     132             :  *   try_to_wake_up(). This latter uses p->pi_lock to serialize against
     133             :  *   concurrent self.
     134             :  *
     135             :  * p->on_rq <- { 0, 1 = TASK_ON_RQ_QUEUED, 2 = TASK_ON_RQ_MIGRATING }:
     136             :  *
     137             :  *   is set by activate_task() and cleared by deactivate_task(), under
     138             :  *   rq->lock. Non-zero indicates the task is runnable, the special
     139             :  *   ON_RQ_MIGRATING state is used for migration without holding both
     140             :  *   rq->locks. It indicates task_cpu() is not stable, see task_rq_lock().
     141             :  *
     142             :  * p->on_cpu <- { 0, 1 }:
     143             :  *
     144             :  *   is set by prepare_task() and cleared by finish_task() such that it will be
     145             :  *   set before p is scheduled-in and cleared after p is scheduled-out, both
     146             :  *   under rq->lock. Non-zero indicates the task is running on its CPU.
     147             :  *
     148             :  *   [ The astute reader will observe that it is possible for two tasks on one
     149             :  *     CPU to have ->on_cpu = 1 at the same time. ]
     150             :  *
     151             :  * task_cpu(p): is changed by set_task_cpu(), the rules are:
     152             :  *
     153             :  *  - Don't call set_task_cpu() on a blocked task:
     154             :  *
     155             :  *    We don't care what CPU we're not running on, this simplifies hotplug,
     156             :  *    the CPU assignment of blocked tasks isn't required to be valid.
     157             :  *
     158             :  *  - for try_to_wake_up(), called under p->pi_lock:
     159             :  *
     160             :  *    This allows try_to_wake_up() to only take one rq->lock, see its comment.
     161             :  *
     162             :  *  - for migration called under rq->lock:
     163             :  *    [ see task_on_rq_migrating() in task_rq_lock() ]
     164             :  *
     165             :  *    o move_queued_task()
     166             :  *    o detach_task()
     167             :  *
     168             :  *  - for migration called under double_rq_lock():
     169             :  *
     170             :  *    o __migrate_swap_task()
     171             :  *    o push_rt_task() / pull_rt_task()
     172             :  *    o push_dl_task() / pull_dl_task()
     173             :  *    o dl_task_offline_migration()
     174             :  *
     175             :  */
     176             : 
     177             : /*
     178             :  * __task_rq_lock - lock the rq @p resides on.
     179             :  */
     180        1148 : struct rq *__task_rq_lock(struct task_struct *p, struct rq_flags *rf)
     181             :         __acquires(rq->lock)
     182             : {
     183        1148 :         struct rq *rq;
     184             : 
     185        2296 :         lockdep_assert_held(&p->pi_lock);
     186             : 
     187        1148 :         for (;;) {
     188        1148 :                 rq = task_rq(p);
     189        1148 :                 raw_spin_lock(&rq->lock);
     190        1148 :                 if (likely(rq == task_rq(p) && !task_on_rq_migrating(p))) {
     191        1148 :                         rq_pin_lock(rq, rf);
     192        1148 :                         return rq;
     193             :                 }
     194           0 :                 raw_spin_unlock(&rq->lock);
     195             : 
     196           0 :                 while (unlikely(task_on_rq_migrating(p)))
     197           0 :                         cpu_relax();
     198             :         }
     199             : }
     200             : 
     201             : /*
     202             :  * task_rq_lock - lock p->pi_lock and lock the rq @p resides on.
     203             :  */
     204         271 : struct rq *task_rq_lock(struct task_struct *p, struct rq_flags *rf)
     205             :         __acquires(p->pi_lock)
     206             :         __acquires(rq->lock)
     207             : {
     208         271 :         struct rq *rq;
     209             : 
     210         271 :         for (;;) {
     211         271 :                 raw_spin_lock_irqsave(&p->pi_lock, rf->flags);
     212         271 :                 rq = task_rq(p);
     213         271 :                 raw_spin_lock(&rq->lock);
     214             :                 /*
     215             :                  *      move_queued_task()              task_rq_lock()
     216             :                  *
     217             :                  *      ACQUIRE (rq->lock)
     218             :                  *      [S] ->on_rq = MIGRATING              [L] rq = task_rq()
     219             :                  *      WMB (__set_task_cpu())          ACQUIRE (rq->lock);
     220             :                  *      [S] ->cpu = new_cpu          [L] task_rq()
     221             :                  *                                      [L] ->on_rq
     222             :                  *      RELEASE (rq->lock)
     223             :                  *
     224             :                  * If we observe the old CPU in task_rq_lock(), the acquire of
     225             :                  * the old rq->lock will fully serialize against the stores.
     226             :                  *
     227             :                  * If we observe the new CPU in task_rq_lock(), the address
     228             :                  * dependency headed by '[L] rq = task_rq()' and the acquire
     229             :                  * will pair with the WMB to ensure we then also see migrating.
     230             :                  */
     231         271 :                 if (likely(rq == task_rq(p) && !task_on_rq_migrating(p))) {
     232         271 :                         rq_pin_lock(rq, rf);
     233         271 :                         return rq;
     234             :                 }
     235           0 :                 raw_spin_unlock(&rq->lock);
     236           0 :                 raw_spin_unlock_irqrestore(&p->pi_lock, rf->flags);
     237             : 
     238           0 :                 while (unlikely(task_on_rq_migrating(p)))
     239           0 :                         cpu_relax();
     240             :         }
     241             : }
     242             : 
     243             : /*
     244             :  * RQ-clock updating methods:
     245             :  */
     246             : 
     247       72902 : static void update_rq_clock_task(struct rq *rq, s64 delta)
     248             : {
     249             : /*
     250             :  * In theory, the compile should just see 0 here, and optimize out the call
     251             :  * to sched_rt_avg_update. But I don't trust it...
     252             :  */
     253       72902 :         s64 __maybe_unused steal = 0, irq_delta = 0;
     254             : 
     255             : #ifdef CONFIG_IRQ_TIME_ACCOUNTING
     256             :         irq_delta = irq_time_read(cpu_of(rq)) - rq->prev_irq_time;
     257             : 
     258             :         /*
     259             :          * Since irq_time is only updated on {soft,}irq_exit, we might run into
     260             :          * this case when a previous update_rq_clock() happened inside a
     261             :          * {soft,}irq region.
     262             :          *
     263             :          * When this happens, we stop ->clock_task and only update the
     264             :          * prev_irq_time stamp to account for the part that fit, so that a next
     265             :          * update will consume the rest. This ensures ->clock_task is
     266             :          * monotonic.
     267             :          *
     268             :          * It does however cause some slight miss-attribution of {soft,}irq
     269             :          * time, a more accurate solution would be to update the irq_time using
     270             :          * the current rq->clock timestamp, except that would require using
     271             :          * atomic ops.
     272             :          */
     273             :         if (irq_delta > delta)
     274             :                 irq_delta = delta;
     275             : 
     276             :         rq->prev_irq_time += irq_delta;
     277             :         delta -= irq_delta;
     278             : #endif
     279             : #ifdef CONFIG_PARAVIRT_TIME_ACCOUNTING
     280       72902 :         if (static_key_false((&paravirt_steal_rq_enabled))) {
     281       71456 :                 steal = paravirt_steal_clock(cpu_of(rq));
     282       71441 :                 steal -= rq->prev_steal_time_rq;
     283             : 
     284       71441 :                 if (unlikely(steal > delta))
     285         112 :                         steal = delta;
     286             : 
     287       71441 :                 rq->prev_steal_time_rq += steal;
     288       71441 :                 delta -= steal;
     289             :         }
     290             : #endif
     291             : 
     292       72786 :         rq->clock_task += delta;
     293             : 
     294             : #ifdef CONFIG_HAVE_SCHED_AVG_IRQ
     295       72786 :         if ((irq_delta + steal) && sched_feat(NONTASK_CAPACITY))
     296        7253 :                 update_irq_load_avg(rq, irq_delta + steal);
     297             : #endif
     298       72767 :         update_rq_clock_pelt(rq, delta);
     299       72939 : }
     300             : 
     301       84069 : void update_rq_clock(struct rq *rq)
     302             : {
     303       84069 :         s64 delta;
     304             : 
     305      169119 :         lockdep_assert_held(&rq->lock);
     306             : 
     307       84055 :         if (rq->clock_update_flags & RQCF_ACT_SKIP)
     308             :                 return;
     309             : 
     310             : #ifdef CONFIG_SCHED_DEBUG
     311             :         if (sched_feat(WARN_DOUBLE_CLOCK))
     312             :                 SCHED_WARN_ON(rq->clock_update_flags & RQCF_UPDATED);
     313             :         rq->clock_update_flags |= RQCF_UPDATED;
     314             : #endif
     315             : 
     316       72942 :         delta = sched_clock_cpu(cpu_of(rq)) - rq->clock;
     317       72950 :         if (delta < 0)
     318             :                 return;
     319       72950 :         rq->clock += delta;
     320       72950 :         update_rq_clock_task(rq, delta);
     321             : }
     322             : 
     323             : #ifdef CONFIG_SCHED_HRTICK
     324             : /*
     325             :  * Use HR-timers to deliver accurate preemption points.
     326             :  */
     327             : 
     328             : static void hrtick_clear(struct rq *rq)
     329             : {
     330             :         if (hrtimer_active(&rq->hrtick_timer))
     331             :                 hrtimer_cancel(&rq->hrtick_timer);
     332             : }
     333             : 
     334             : /*
     335             :  * High-resolution timer tick.
     336             :  * Runs from hardirq context with interrupts disabled.
     337             :  */
     338             : static enum hrtimer_restart hrtick(struct hrtimer *timer)
     339             : {
     340             :         struct rq *rq = container_of(timer, struct rq, hrtick_timer);
     341             :         struct rq_flags rf;
     342             : 
     343             :         WARN_ON_ONCE(cpu_of(rq) != smp_processor_id());
     344             : 
     345             :         rq_lock(rq, &rf);
     346             :         update_rq_clock(rq);
     347             :         rq->curr->sched_class->task_tick(rq, rq->curr, 1);
     348             :         rq_unlock(rq, &rf);
     349             : 
     350             :         return HRTIMER_NORESTART;
     351             : }
     352             : 
     353             : #ifdef CONFIG_SMP
     354             : 
     355             : static void __hrtick_restart(struct rq *rq)
     356             : {
     357             :         struct hrtimer *timer = &rq->hrtick_timer;
     358             :         ktime_t time = rq->hrtick_time;
     359             : 
     360             :         hrtimer_start(timer, time, HRTIMER_MODE_ABS_PINNED_HARD);
     361             : }
     362             : 
     363             : /*
     364             :  * called from hardirq (IPI) context
     365             :  */
     366             : static void __hrtick_start(void *arg)
     367             : {
     368             :         struct rq *rq = arg;
     369             :         struct rq_flags rf;
     370             : 
     371             :         rq_lock(rq, &rf);
     372             :         __hrtick_restart(rq);
     373             :         rq_unlock(rq, &rf);
     374             : }
     375             : 
     376             : /*
     377             :  * Called to set the hrtick timer state.
     378             :  *
     379             :  * called with rq->lock held and irqs disabled
     380             :  */
     381             : void hrtick_start(struct rq *rq, u64 delay)
     382             : {
     383             :         struct hrtimer *timer = &rq->hrtick_timer;
     384             :         s64 delta;
     385             : 
     386             :         /*
     387             :          * Don't schedule slices shorter than 10000ns, that just
     388             :          * doesn't make sense and can cause timer DoS.
     389             :          */
     390             :         delta = max_t(s64, delay, 10000LL);
     391             :         rq->hrtick_time = ktime_add_ns(timer->base->get_time(), delta);
     392             : 
     393             :         if (rq == this_rq())
     394             :                 __hrtick_restart(rq);
     395             :         else
     396             :                 smp_call_function_single_async(cpu_of(rq), &rq->hrtick_csd);
     397             : }
     398             : 
     399             : #else
     400             : /*
     401             :  * Called to set the hrtick timer state.
     402             :  *
     403             :  * called with rq->lock held and irqs disabled
     404             :  */
     405             : void hrtick_start(struct rq *rq, u64 delay)
     406             : {
     407             :         /*
     408             :          * Don't schedule slices shorter than 10000ns, that just
     409             :          * doesn't make sense. Rely on vruntime for fairness.
     410             :          */
     411             :         delay = max_t(u64, delay, 10000LL);
     412             :         hrtimer_start(&rq->hrtick_timer, ns_to_ktime(delay),
     413             :                       HRTIMER_MODE_REL_PINNED_HARD);
     414             : }
     415             : 
     416             : #endif /* CONFIG_SMP */
     417             : 
     418             : static void hrtick_rq_init(struct rq *rq)
     419             : {
     420             : #ifdef CONFIG_SMP
     421             :         INIT_CSD(&rq->hrtick_csd, __hrtick_start, rq);
     422             : #endif
     423             :         hrtimer_init(&rq->hrtick_timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL_HARD);
     424             :         rq->hrtick_timer.function = hrtick;
     425             : }
     426             : #else   /* CONFIG_SCHED_HRTICK */
     427           0 : static inline void hrtick_clear(struct rq *rq)
     428             : {
     429           0 : }
     430             : 
     431           4 : static inline void hrtick_rq_init(struct rq *rq)
     432             : {
     433           4 : }
     434             : #endif  /* CONFIG_SCHED_HRTICK */
     435             : 
     436             : /*
     437             :  * cmpxchg based fetch_or, macro so it works for different integer types
     438             :  */
     439             : #define fetch_or(ptr, mask)                                             \
     440             :         ({                                                              \
     441             :                 typeof(ptr) _ptr = (ptr);                               \
     442             :                 typeof(mask) _mask = (mask);                            \
     443             :                 typeof(*_ptr) _old, _val = *_ptr;                       \
     444             :                                                                         \
     445             :                 for (;;) {                                              \
     446             :                         _old = cmpxchg(_ptr, _val, _val | _mask);       \
     447             :                         if (_old == _val)                               \
     448             :                                 break;                                  \
     449             :                         _val = _old;                                    \
     450             :                 }                                                       \
     451             :         _old;                                                           \
     452             : })
     453             : 
     454             : #if defined(CONFIG_SMP) && defined(TIF_POLLING_NRFLAG)
     455             : /*
     456             :  * Atomically set TIF_NEED_RESCHED and test for TIF_POLLING_NRFLAG,
     457             :  * this avoids any races wrt polling state changes and thereby avoids
     458             :  * spurious IPIs.
     459             :  */
     460         746 : static bool set_nr_and_not_polling(struct task_struct *p)
     461             : {
     462         746 :         struct thread_info *ti = task_thread_info(p);
     463         746 :         return !(fetch_or(&ti->flags, _TIF_NEED_RESCHED) & _TIF_POLLING_NRFLAG);
     464             : }
     465             : 
     466             : /*
     467             :  * Atomically set TIF_NEED_RESCHED if TIF_POLLING_NRFLAG is set.
     468             :  *
     469             :  * If this returns true, then the idle task promises to call
     470             :  * sched_ttwu_pending() and reschedule soon.
     471             :  */
     472        7103 : static bool set_nr_if_polling(struct task_struct *p)
     473             : {
     474        7103 :         struct thread_info *ti = task_thread_info(p);
     475        7103 :         typeof(ti->flags) old, val = READ_ONCE(ti->flags);
     476             : 
     477        7103 :         for (;;) {
     478        7103 :                 if (!(val & _TIF_POLLING_NRFLAG))
     479             :                         return false;
     480          28 :                 if (val & _TIF_NEED_RESCHED)
     481             :                         return true;
     482          28 :                 old = cmpxchg(&ti->flags, val, val | _TIF_NEED_RESCHED);
     483          28 :                 if (old == val)
     484             :                         break;
     485             :                 val = old;
     486             :         }
     487             :         return true;
     488             : }
     489             : 
     490             : #else
     491             : static bool set_nr_and_not_polling(struct task_struct *p)
     492             : {
     493             :         set_tsk_need_resched(p);
     494             :         return true;
     495             : }
     496             : 
     497             : #ifdef CONFIG_SMP
     498             : static bool set_nr_if_polling(struct task_struct *p)
     499             : {
     500             :         return false;
     501             : }
     502             : #endif
     503             : #endif
     504             : 
     505         620 : static bool __wake_q_add(struct wake_q_head *head, struct task_struct *task)
     506             : {
     507         620 :         struct wake_q_node *node = &task->wake_q;
     508             : 
     509             :         /*
     510             :          * Atomically grab the task, if ->wake_q is !nil already it means
     511             :          * it's already queued (either by us or someone else) and will get the
     512             :          * wakeup due to that.
     513             :          *
     514             :          * In order to ensure that a pending wakeup will observe our pending
     515             :          * state, even in the failed case, an explicit smp_mb() must be used.
     516             :          */
     517         620 :         smp_mb__before_atomic();
     518         620 :         if (unlikely(cmpxchg_relaxed(&node->next, NULL, WAKE_Q_TAIL)))
     519             :                 return false;
     520             : 
     521             :         /*
     522             :          * The head is context local, there can be no concurrency.
     523             :          */
     524         620 :         *head->lastp = node;
     525         620 :         head->lastp = &node->next;
     526         620 :         return true;
     527             : }
     528             : 
     529             : /**
     530             :  * wake_q_add() - queue a wakeup for 'later' waking.
     531             :  * @head: the wake_q_head to add @task to
     532             :  * @task: the task to queue for 'later' wakeup
     533             :  *
     534             :  * Queue a task for later wakeup, most likely by the wake_up_q() call in the
     535             :  * same context, _HOWEVER_ this is not guaranteed, the wakeup can come
     536             :  * instantly.
     537             :  *
     538             :  * This function must be used as-if it were wake_up_process(); IOW the task
     539             :  * must be ready to be woken at this location.
     540             :  */
     541         382 : void wake_q_add(struct wake_q_head *head, struct task_struct *task)
     542             : {
     543         382 :         if (__wake_q_add(head, task))
     544         382 :                 get_task_struct(task);
     545         382 : }
     546             : 
     547             : /**
     548             :  * wake_q_add_safe() - safely queue a wakeup for 'later' waking.
     549             :  * @head: the wake_q_head to add @task to
     550             :  * @task: the task to queue for 'later' wakeup
     551             :  *
     552             :  * Queue a task for later wakeup, most likely by the wake_up_q() call in the
     553             :  * same context, _HOWEVER_ this is not guaranteed, the wakeup can come
     554             :  * instantly.
     555             :  *
     556             :  * This function must be used as-if it were wake_up_process(); IOW the task
     557             :  * must be ready to be woken at this location.
     558             :  *
     559             :  * This function is essentially a task-safe equivalent to wake_q_add(). Callers
     560             :  * that already hold reference to @task can call the 'safe' version and trust
     561             :  * wake_q to do the right thing depending whether or not the @task is already
     562             :  * queued for wakeup.
     563             :  */
     564         238 : void wake_q_add_safe(struct wake_q_head *head, struct task_struct *task)
     565             : {
     566         238 :         if (!__wake_q_add(head, task))
     567           0 :                 put_task_struct(task);
     568         238 : }
     569             : 
     570         703 : void wake_up_q(struct wake_q_head *head)
     571             : {
     572         703 :         struct wake_q_node *node = head->first;
     573             : 
     574        1323 :         while (node != WAKE_Q_TAIL) {
     575         620 :                 struct task_struct *task;
     576             : 
     577         620 :                 task = container_of(node, struct task_struct, wake_q);
     578         620 :                 BUG_ON(!task);
     579             :                 /* Task can safely be re-inserted now: */
     580         620 :                 node = node->next;
     581         620 :                 task->wake_q.next = NULL;
     582             : 
     583             :                 /*
     584             :                  * wake_up_process() executes a full barrier, which pairs with
     585             :                  * the queueing in wake_q_add() so as not to miss wakeups.
     586             :                  */
     587        1240 :                 wake_up_process(task);
     588         620 :                 put_task_struct(task);
     589             :         }
     590         703 : }
     591             : 
     592             : /*
     593             :  * resched_curr - mark rq's current task 'to be rescheduled now'.
     594             :  *
     595             :  * On UP this means the setting of the need_resched flag, on SMP it
     596             :  * might also involve a cross-CPU call to trigger the scheduler on
     597             :  * the target CPU.
     598             :  */
     599       13562 : void resched_curr(struct rq *rq)
     600             : {
     601       13562 :         struct task_struct *curr = rq->curr;
     602       13562 :         int cpu;
     603             : 
     604       27140 :         lockdep_assert_held(&rq->lock);
     605             : 
     606       13569 :         if (test_tsk_need_resched(curr))
     607             :                 return;
     608             : 
     609       12600 :         cpu = cpu_of(rq);
     610             : 
     611       12600 :         if (cpu == smp_processor_id()) {
     612       11862 :                 set_tsk_need_resched(curr);
     613       11868 :                 set_preempt_need_resched();
     614       11868 :                 return;
     615             :         }
     616             : 
     617         738 :         if (set_nr_and_not_polling(curr))
     618         738 :                 smp_send_reschedule(cpu);
     619             :         else
     620           0 :                 trace_sched_wake_idle_without_ipi(cpu);
     621             : }
     622             : 
     623           0 : void resched_cpu(int cpu)
     624             : {
     625           0 :         struct rq *rq = cpu_rq(cpu);
     626           0 :         unsigned long flags;
     627             : 
     628           0 :         raw_spin_lock_irqsave(&rq->lock, flags);
     629           0 :         if (cpu_online(cpu) || cpu == smp_processor_id())
     630           0 :                 resched_curr(rq);
     631           0 :         raw_spin_unlock_irqrestore(&rq->lock, flags);
     632           0 : }
     633             : 
     634             : #ifdef CONFIG_SMP
     635             : #ifdef CONFIG_NO_HZ_COMMON
     636             : /*
     637             :  * In the semi idle case, use the nearest busy CPU for migrating timers
     638             :  * from an idle CPU.  This is good for power-savings.
     639             :  *
     640             :  * We don't do similar optimization for completely idle system, as
     641             :  * selecting an idle CPU will add more delays to the timers than intended
     642             :  * (as that CPU's timer base may not be uptodate wrt jiffies etc).
     643             :  */
     644        5340 : int get_nohz_timer_target(void)
     645             : {
     646        5340 :         int i, cpu = smp_processor_id(), default_cpu = -1;
     647        5340 :         struct sched_domain *sd;
     648             : 
     649        5340 :         if (housekeeping_cpu(cpu, HK_FLAG_TIMER)) {
     650        5340 :                 if (!idle_cpu(cpu))
     651             :                         return cpu;
     652          53 :                 default_cpu = cpu;
     653             :         }
     654             : 
     655          53 :         rcu_read_lock();
     656         167 :         for_each_domain(cpu, sd) {
     657         115 :                 for_each_cpu_and(i, sched_domain_span(sd),
     658             :                         housekeeping_cpumask(HK_FLAG_TIMER)) {
     659         107 :                         if (cpu == i)
     660          22 :                                 continue;
     661             : 
     662          85 :                         if (!idle_cpu(i)) {
     663          45 :                                 cpu = i;
     664          45 :                                 goto unlock;
     665             :                         }
     666             :                 }
     667             :         }
     668             : 
     669           8 :         if (default_cpu == -1)
     670           0 :                 default_cpu = housekeeping_any_cpu(HK_FLAG_TIMER);
     671             :         cpu = default_cpu;
     672          53 : unlock:
     673          53 :         rcu_read_unlock();
     674          53 :         return cpu;
     675             : }
     676             : 
     677             : /*
     678             :  * When add_timer_on() enqueues a timer into the timer wheel of an
     679             :  * idle CPU then this timer might expire before the next timer event
     680             :  * which is scheduled to wake up that CPU. In case of a completely
     681             :  * idle system the next event might even be infinite time into the
     682             :  * future. wake_up_idle_cpu() ensures that the CPU is woken up and
     683             :  * leaves the inner idle loop so the newly added timer is taken into
     684             :  * account when the CPU goes back to idle and evaluates the timer
     685             :  * wheel for the next timer event.
     686             :  */
     687           9 : static void wake_up_idle_cpu(int cpu)
     688             : {
     689           9 :         struct rq *rq = cpu_rq(cpu);
     690             : 
     691           9 :         if (cpu == smp_processor_id())
     692             :                 return;
     693             : 
     694           8 :         if (set_nr_and_not_polling(rq->idle))
     695           8 :                 smp_send_reschedule(cpu);
     696             :         else
     697           0 :                 trace_sched_wake_idle_without_ipi(cpu);
     698             : }
     699             : 
     700           9 : static bool wake_up_full_nohz_cpu(int cpu)
     701             : {
     702             :         /*
     703             :          * We just need the target to call irq_exit() and re-evaluate
     704             :          * the next tick. The nohz full kick at least implies that.
     705             :          * If needed we can still optimize that later with an
     706             :          * empty IRQ.
     707             :          */
     708           9 :         if (cpu_is_offline(cpu))
     709           0 :                 return true;  /* Don't try to wake offline CPUs. */
     710           9 :         if (tick_nohz_full_cpu(cpu)) {
     711             :                 if (cpu != smp_processor_id() ||
     712             :                     tick_nohz_tick_stopped())
     713             :                         tick_nohz_full_kick_cpu(cpu);
     714             :                 return true;
     715             :         }
     716             : 
     717             :         return false;
     718             : }
     719             : 
     720             : /*
     721             :  * Wake up the specified CPU.  If the CPU is going offline, it is the
     722             :  * caller's responsibility to deal with the lost wakeup, for example,
     723             :  * by hooking into the CPU_DEAD notifier like timers and hrtimers do.
     724             :  */
     725           9 : void wake_up_nohz_cpu(int cpu)
     726             : {
     727           9 :         if (!wake_up_full_nohz_cpu(cpu))
     728           9 :                 wake_up_idle_cpu(cpu);
     729           9 : }
     730             : 
     731         220 : static void nohz_csd_func(void *info)
     732             : {
     733         220 :         struct rq *rq = info;
     734         220 :         int cpu = cpu_of(rq);
     735         220 :         unsigned int flags;
     736             : 
     737             :         /*
     738             :          * Release the rq::nohz_csd.
     739             :          */
     740         220 :         flags = atomic_fetch_andnot(NOHZ_KICK_MASK, nohz_flags(cpu));
     741         220 :         WARN_ON(!(flags & NOHZ_KICK_MASK));
     742             : 
     743         220 :         rq->idle_balance = idle_cpu(cpu);
     744         431 :         if (rq->idle_balance && !need_resched()) {
     745         211 :                 rq->nohz_idle_balance = flags;
     746         211 :                 raise_softirq_irqoff(SCHED_SOFTIRQ);
     747             :         }
     748         220 : }
     749             : 
     750             : #endif /* CONFIG_NO_HZ_COMMON */
     751             : 
     752             : #ifdef CONFIG_NO_HZ_FULL
     753             : bool sched_can_stop_tick(struct rq *rq)
     754             : {
     755             :         int fifo_nr_running;
     756             : 
     757             :         /* Deadline tasks, even if single, need the tick */
     758             :         if (rq->dl.dl_nr_running)
     759             :                 return false;
     760             : 
     761             :         /*
     762             :          * If there are more than one RR tasks, we need the tick to affect the
     763             :          * actual RR behaviour.
     764             :          */
     765             :         if (rq->rt.rr_nr_running) {
     766             :                 if (rq->rt.rr_nr_running == 1)
     767             :                         return true;
     768             :                 else
     769             :                         return false;
     770             :         }
     771             : 
     772             :         /*
     773             :          * If there's no RR tasks, but FIFO tasks, we can skip the tick, no
     774             :          * forced preemption between FIFO tasks.
     775             :          */
     776             :         fifo_nr_running = rq->rt.rt_nr_running - rq->rt.rr_nr_running;
     777             :         if (fifo_nr_running)
     778             :                 return true;
     779             : 
     780             :         /*
     781             :          * If there are no DL,RR/FIFO tasks, there must only be CFS tasks left;
     782             :          * if there's more than one we need the tick for involuntary
     783             :          * preemption.
     784             :          */
     785             :         if (rq->nr_running > 1)
     786             :                 return false;
     787             : 
     788             :         return true;
     789             : }
     790             : #endif /* CONFIG_NO_HZ_FULL */
     791             : #endif /* CONFIG_SMP */
     792             : 
     793             : #if defined(CONFIG_RT_GROUP_SCHED) || (defined(CONFIG_FAIR_GROUP_SCHED) && \
     794             :                         (defined(CONFIG_SMP) || defined(CONFIG_CFS_BANDWIDTH)))
     795             : /*
     796             :  * Iterate task_group tree rooted at *from, calling @down when first entering a
     797             :  * node and @up when leaving it for the final time.
     798             :  *
     799             :  * Caller must hold rcu_lock or sufficient equivalent.
     800             :  */
     801             : int walk_tg_tree_from(struct task_group *from,
     802             :                              tg_visitor down, tg_visitor up, void *data)
     803             : {
     804             :         struct task_group *parent, *child;
     805             :         int ret;
     806             : 
     807             :         parent = from;
     808             : 
     809             : down:
     810             :         ret = (*down)(parent, data);
     811             :         if (ret)
     812             :                 goto out;
     813             :         list_for_each_entry_rcu(child, &parent->children, siblings) {
     814             :                 parent = child;
     815             :                 goto down;
     816             : 
     817             : up:
     818             :                 continue;
     819             :         }
     820             :         ret = (*up)(parent, data);
     821             :         if (ret || parent == from)
     822             :                 goto out;
     823             : 
     824             :         child = parent;
     825             :         parent = parent->parent;
     826             :         if (parent)
     827             :                 goto up;
     828             : out:
     829             :         return ret;
     830             : }
     831             : 
     832             : int tg_nop(struct task_group *tg, void *data)
     833             : {
     834             :         return 0;
     835             : }
     836             : #endif
     837             : 
     838          26 : static void set_load_weight(struct task_struct *p, bool update_load)
     839             : {
     840          26 :         int prio = p->static_prio - MAX_RT_PRIO;
     841          26 :         struct load_weight *load = &p->se.load;
     842             : 
     843             :         /*
     844             :          * SCHED_IDLE tasks get minimal weight:
     845             :          */
     846          26 :         if (task_has_idle_policy(p)) {
     847           0 :                 load->weight = scale_load(WEIGHT_IDLEPRIO);
     848           0 :                 load->inv_weight = WMULT_IDLEPRIO;
     849           0 :                 return;
     850             :         }
     851             : 
     852             :         /*
     853             :          * SCHED_OTHER tasks have to update their load when changing their
     854             :          * weight
     855             :          */
     856          26 :         if (update_load && p->sched_class == &fair_sched_class) {
     857          25 :                 reweight_task(p, prio);
     858             :         } else {
     859           1 :                 load->weight = scale_load(sched_prio_to_weight[prio]);
     860           1 :                 load->inv_weight = sched_prio_to_wmult[prio];
     861             :         }
     862             : }
     863             : 
     864             : #ifdef CONFIG_UCLAMP_TASK
     865             : /*
     866             :  * Serializes updates of utilization clamp values
     867             :  *
     868             :  * The (slow-path) user-space triggers utilization clamp value updates which
     869             :  * can require updates on (fast-path) scheduler's data structures used to
     870             :  * support enqueue/dequeue operations.
     871             :  * While the per-CPU rq lock protects fast-path update operations, user-space
     872             :  * requests are serialized using a mutex to reduce the risk of conflicting
     873             :  * updates or API abuses.
     874             :  */
     875             : static DEFINE_MUTEX(uclamp_mutex);
     876             : 
     877             : /* Max allowed minimum utilization */
     878             : unsigned int sysctl_sched_uclamp_util_min = SCHED_CAPACITY_SCALE;
     879             : 
     880             : /* Max allowed maximum utilization */
     881             : unsigned int sysctl_sched_uclamp_util_max = SCHED_CAPACITY_SCALE;
     882             : 
     883             : /*
     884             :  * By default RT tasks run at the maximum performance point/capacity of the
     885             :  * system. Uclamp enforces this by always setting UCLAMP_MIN of RT tasks to
     886             :  * SCHED_CAPACITY_SCALE.
     887             :  *
     888             :  * This knob allows admins to change the default behavior when uclamp is being
     889             :  * used. In battery powered devices, particularly, running at the maximum
     890             :  * capacity and frequency will increase energy consumption and shorten the
     891             :  * battery life.
     892             :  *
     893             :  * This knob only affects RT tasks that their uclamp_se->user_defined == false.
     894             :  *
     895             :  * This knob will not override the system default sched_util_clamp_min defined
     896             :  * above.
     897             :  */
     898             : unsigned int sysctl_sched_uclamp_util_min_rt_default = SCHED_CAPACITY_SCALE;
     899             : 
     900             : /* All clamps are required to be less or equal than these values */
     901             : static struct uclamp_se uclamp_default[UCLAMP_CNT];
     902             : 
     903             : /*
     904             :  * This static key is used to reduce the uclamp overhead in the fast path. It
     905             :  * primarily disables the call to uclamp_rq_{inc, dec}() in
     906             :  * enqueue/dequeue_task().
     907             :  *
     908             :  * This allows users to continue to enable uclamp in their kernel config with
     909             :  * minimum uclamp overhead in the fast path.
     910             :  *
     911             :  * As soon as userspace modifies any of the uclamp knobs, the static key is
     912             :  * enabled, since we have an actual users that make use of uclamp
     913             :  * functionality.
     914             :  *
     915             :  * The knobs that would enable this static key are:
     916             :  *
     917             :  *   * A task modifying its uclamp value with sched_setattr().
     918             :  *   * An admin modifying the sysctl_sched_uclamp_{min, max} via procfs.
     919             :  *   * An admin modifying the cgroup cpu.uclamp.{min, max}
     920             :  */
     921             : DEFINE_STATIC_KEY_FALSE(sched_uclamp_used);
     922             : 
     923             : /* Integer rounded range for each bucket */
     924             : #define UCLAMP_BUCKET_DELTA DIV_ROUND_CLOSEST(SCHED_CAPACITY_SCALE, UCLAMP_BUCKETS)
     925             : 
     926             : #define for_each_clamp_id(clamp_id) \
     927             :         for ((clamp_id) = 0; (clamp_id) < UCLAMP_CNT; (clamp_id)++)
     928             : 
     929             : static inline unsigned int uclamp_bucket_id(unsigned int clamp_value)
     930             : {
     931             :         return clamp_value / UCLAMP_BUCKET_DELTA;
     932             : }
     933             : 
     934             : static inline unsigned int uclamp_none(enum uclamp_id clamp_id)
     935             : {
     936             :         if (clamp_id == UCLAMP_MIN)
     937             :                 return 0;
     938             :         return SCHED_CAPACITY_SCALE;
     939             : }
     940             : 
     941             : static inline void uclamp_se_set(struct uclamp_se *uc_se,
     942             :                                  unsigned int value, bool user_defined)
     943             : {
     944             :         uc_se->value = value;
     945             :         uc_se->bucket_id = uclamp_bucket_id(value);
     946             :         uc_se->user_defined = user_defined;
     947             : }
     948             : 
     949             : static inline unsigned int
     950             : uclamp_idle_value(struct rq *rq, enum uclamp_id clamp_id,
     951             :                   unsigned int clamp_value)
     952             : {
     953             :         /*
     954             :          * Avoid blocked utilization pushing up the frequency when we go
     955             :          * idle (which drops the max-clamp) by retaining the last known
     956             :          * max-clamp.
     957             :          */
     958             :         if (clamp_id == UCLAMP_MAX) {
     959             :                 rq->uclamp_flags |= UCLAMP_FLAG_IDLE;
     960             :                 return clamp_value;
     961             :         }
     962             : 
     963             :         return uclamp_none(UCLAMP_MIN);
     964             : }
     965             : 
     966             : static inline void uclamp_idle_reset(struct rq *rq, enum uclamp_id clamp_id,
     967             :                                      unsigned int clamp_value)
     968             : {
     969             :         /* Reset max-clamp retention only on idle exit */
     970             :         if (!(rq->uclamp_flags & UCLAMP_FLAG_IDLE))
     971             :                 return;
     972             : 
     973             :         WRITE_ONCE(rq->uclamp[clamp_id].value, clamp_value);
     974             : }
     975             : 
     976             : static inline
     977             : unsigned int uclamp_rq_max_value(struct rq *rq, enum uclamp_id clamp_id,
     978             :                                    unsigned int clamp_value)
     979             : {
     980             :         struct uclamp_bucket *bucket = rq->uclamp[clamp_id].bucket;
     981             :         int bucket_id = UCLAMP_BUCKETS - 1;
     982             : 
     983             :         /*
     984             :          * Since both min and max clamps are max aggregated, find the
     985             :          * top most bucket with tasks in.
     986             :          */
     987             :         for ( ; bucket_id >= 0; bucket_id--) {
     988             :                 if (!bucket[bucket_id].tasks)
     989             :                         continue;
     990             :                 return bucket[bucket_id].value;
     991             :         }
     992             : 
     993             :         /* No tasks -- default clamp values */
     994             :         return uclamp_idle_value(rq, clamp_id, clamp_value);
     995             : }
     996             : 
     997             : static void __uclamp_update_util_min_rt_default(struct task_struct *p)
     998             : {
     999             :         unsigned int default_util_min;
    1000             :         struct uclamp_se *uc_se;
    1001             : 
    1002             :         lockdep_assert_held(&p->pi_lock);
    1003             : 
    1004             :         uc_se = &p->uclamp_req[UCLAMP_MIN];
    1005             : 
    1006             :         /* Only sync if user didn't override the default */
    1007             :         if (uc_se->user_defined)
    1008             :                 return;
    1009             : 
    1010             :         default_util_min = sysctl_sched_uclamp_util_min_rt_default;
    1011             :         uclamp_se_set(uc_se, default_util_min, false);
    1012             : }
    1013             : 
    1014             : static void uclamp_update_util_min_rt_default(struct task_struct *p)
    1015             : {
    1016             :         struct rq_flags rf;
    1017             :         struct rq *rq;
    1018             : 
    1019             :         if (!rt_task(p))
    1020             :                 return;
    1021             : 
    1022             :         /* Protect updates to p->uclamp_* */
    1023             :         rq = task_rq_lock(p, &rf);
    1024             :         __uclamp_update_util_min_rt_default(p);
    1025             :         task_rq_unlock(rq, p, &rf);
    1026             : }
    1027             : 
    1028             : static void uclamp_sync_util_min_rt_default(void)
    1029             : {
    1030             :         struct task_struct *g, *p;
    1031             : 
    1032             :         /*
    1033             :          * copy_process()                       sysctl_uclamp
    1034             :          *                                        uclamp_min_rt = X;
    1035             :          *   write_lock(&tasklist_lock)               read_lock(&tasklist_lock)
    1036             :          *   // link thread                       smp_mb__after_spinlock()
    1037             :          *   write_unlock(&tasklist_lock)     read_unlock(&tasklist_lock);
    1038             :          *   sched_post_fork()                    for_each_process_thread()
    1039             :          *     __uclamp_sync_rt()                   __uclamp_sync_rt()
    1040             :          *
    1041             :          * Ensures that either sched_post_fork() will observe the new
    1042             :          * uclamp_min_rt or for_each_process_thread() will observe the new
    1043             :          * task.
    1044             :          */
    1045             :         read_lock(&tasklist_lock);
    1046             :         smp_mb__after_spinlock();
    1047             :         read_unlock(&tasklist_lock);
    1048             : 
    1049             :         rcu_read_lock();
    1050             :         for_each_process_thread(g, p)
    1051             :                 uclamp_update_util_min_rt_default(p);
    1052             :         rcu_read_unlock();
    1053             : }
    1054             : 
    1055             : static inline struct uclamp_se
    1056             : uclamp_tg_restrict(struct task_struct *p, enum uclamp_id clamp_id)
    1057             : {
    1058             :         struct uclamp_se uc_req = p->uclamp_req[clamp_id];
    1059             : #ifdef CONFIG_UCLAMP_TASK_GROUP
    1060             :         struct uclamp_se uc_max;
    1061             : 
    1062             :         /*
    1063             :          * Tasks in autogroups or root task group will be
    1064             :          * restricted by system defaults.
    1065             :          */
    1066             :         if (task_group_is_autogroup(task_group(p)))
    1067             :                 return uc_req;
    1068             :         if (task_group(p) == &root_task_group)
    1069             :                 return uc_req;
    1070             : 
    1071             :         uc_max = task_group(p)->uclamp[clamp_id];
    1072             :         if (uc_req.value > uc_max.value || !uc_req.user_defined)
    1073             :                 return uc_max;
    1074             : #endif
    1075             : 
    1076             :         return uc_req;
    1077             : }
    1078             : 
    1079             : /*
    1080             :  * The effective clamp bucket index of a task depends on, by increasing
    1081             :  * priority:
    1082             :  * - the task specific clamp value, when explicitly requested from userspace
    1083             :  * - the task group effective clamp value, for tasks not either in the root
    1084             :  *   group or in an autogroup
    1085             :  * - the system default clamp value, defined by the sysadmin
    1086             :  */
    1087             : static inline struct uclamp_se
    1088             : uclamp_eff_get(struct task_struct *p, enum uclamp_id clamp_id)
    1089             : {
    1090             :         struct uclamp_se uc_req = uclamp_tg_restrict(p, clamp_id);
    1091             :         struct uclamp_se uc_max = uclamp_default[clamp_id];
    1092             : 
    1093             :         /* System default restrictions always apply */
    1094             :         if (unlikely(uc_req.value > uc_max.value))
    1095             :                 return uc_max;
    1096             : 
    1097             :         return uc_req;
    1098             : }
    1099             : 
    1100             : unsigned long uclamp_eff_value(struct task_struct *p, enum uclamp_id clamp_id)
    1101             : {
    1102             :         struct uclamp_se uc_eff;
    1103             : 
    1104             :         /* Task currently refcounted: use back-annotated (effective) value */
    1105             :         if (p->uclamp[clamp_id].active)
    1106             :                 return (unsigned long)p->uclamp[clamp_id].value;
    1107             : 
    1108             :         uc_eff = uclamp_eff_get(p, clamp_id);
    1109             : 
    1110             :         return (unsigned long)uc_eff.value;
    1111             : }
    1112             : 
    1113             : /*
    1114             :  * When a task is enqueued on a rq, the clamp bucket currently defined by the
    1115             :  * task's uclamp::bucket_id is refcounted on that rq. This also immediately
    1116             :  * updates the rq's clamp value if required.
    1117             :  *
    1118             :  * Tasks can have a task-specific value requested from user-space, track
    1119             :  * within each bucket the maximum value for tasks refcounted in it.
    1120             :  * This "local max aggregation" allows to track the exact "requested" value
    1121             :  * for each bucket when all its RUNNABLE tasks require the same clamp.
    1122             :  */
    1123             : static inline void uclamp_rq_inc_id(struct rq *rq, struct task_struct *p,
    1124             :                                     enum uclamp_id clamp_id)
    1125             : {
    1126             :         struct uclamp_rq *uc_rq = &rq->uclamp[clamp_id];
    1127             :         struct uclamp_se *uc_se = &p->uclamp[clamp_id];
    1128             :         struct uclamp_bucket *bucket;
    1129             : 
    1130             :         lockdep_assert_held(&rq->lock);
    1131             : 
    1132             :         /* Update task effective clamp */
    1133             :         p->uclamp[clamp_id] = uclamp_eff_get(p, clamp_id);
    1134             : 
    1135             :         bucket = &uc_rq->bucket[uc_se->bucket_id];
    1136             :         bucket->tasks++;
    1137             :         uc_se->active = true;
    1138             : 
    1139             :         uclamp_idle_reset(rq, clamp_id, uc_se->value);
    1140             : 
    1141             :         /*
    1142             :          * Local max aggregation: rq buckets always track the max
    1143             :          * "requested" clamp value of its RUNNABLE tasks.
    1144             :          */
    1145             :         if (bucket->tasks == 1 || uc_se->value > bucket->value)
    1146             :                 bucket->value = uc_se->value;
    1147             : 
    1148             :         if (uc_se->value > READ_ONCE(uc_rq->value))
    1149             :                 WRITE_ONCE(uc_rq->value, uc_se->value);
    1150             : }
    1151             : 
    1152             : /*
    1153             :  * When a task is dequeued from a rq, the clamp bucket refcounted by the task
    1154             :  * is released. If this is the last task reference counting the rq's max
    1155             :  * active clamp value, then the rq's clamp value is updated.
    1156             :  *
    1157             :  * Both refcounted tasks and rq's cached clamp values are expected to be
    1158             :  * always valid. If it's detected they are not, as defensive programming,
    1159             :  * enforce the expected state and warn.
    1160             :  */
    1161             : static inline void uclamp_rq_dec_id(struct rq *rq, struct task_struct *p,
    1162             :                                     enum uclamp_id clamp_id)
    1163             : {
    1164             :         struct uclamp_rq *uc_rq = &rq->uclamp[clamp_id];
    1165             :         struct uclamp_se *uc_se = &p->uclamp[clamp_id];
    1166             :         struct uclamp_bucket *bucket;
    1167             :         unsigned int bkt_clamp;
    1168             :         unsigned int rq_clamp;
    1169             : 
    1170             :         lockdep_assert_held(&rq->lock);
    1171             : 
    1172             :         /*
    1173             :          * If sched_uclamp_used was enabled after task @p was enqueued,
    1174             :          * we could end up with unbalanced call to uclamp_rq_dec_id().
    1175             :          *
    1176             :          * In this case the uc_se->active flag should be false since no uclamp
    1177             :          * accounting was performed at enqueue time and we can just return
    1178             :          * here.
    1179             :          *
    1180             :          * Need to be careful of the following enqueue/dequeue ordering
    1181             :          * problem too
    1182             :          *
    1183             :          *      enqueue(taskA)
    1184             :          *      // sched_uclamp_used gets enabled
    1185             :          *      enqueue(taskB)
    1186             :          *      dequeue(taskA)
    1187             :          *      // Must not decrement bucket->tasks here
    1188             :          *      dequeue(taskB)
    1189             :          *
    1190             :          * where we could end up with stale data in uc_se and
    1191             :          * bucket[uc_se->bucket_id].
    1192             :          *
    1193             :          * The following check here eliminates the possibility of such race.
    1194             :          */
    1195             :         if (unlikely(!uc_se->active))
    1196             :                 return;
    1197             : 
    1198             :         bucket = &uc_rq->bucket[uc_se->bucket_id];
    1199             : 
    1200             :         SCHED_WARN_ON(!bucket->tasks);
    1201             :         if (likely(bucket->tasks))
    1202             :                 bucket->tasks--;
    1203             : 
    1204             :         uc_se->active = false;
    1205             : 
    1206             :         /*
    1207             :          * Keep "local max aggregation" simple and accept to (possibly)
    1208             :          * overboost some RUNNABLE tasks in the same bucket.
    1209             :          * The rq clamp bucket value is reset to its base value whenever
    1210             :          * there are no more RUNNABLE tasks refcounting it.
    1211             :          */
    1212             :         if (likely(bucket->tasks))
    1213             :                 return;
    1214             : 
    1215             :         rq_clamp = READ_ONCE(uc_rq->value);
    1216             :         /*
    1217             :          * Defensive programming: this should never happen. If it happens,
    1218             :          * e.g. due to future modification, warn and fixup the expected value.
    1219             :          */
    1220             :         SCHED_WARN_ON(bucket->value > rq_clamp);
    1221             :         if (bucket->value >= rq_clamp) {
    1222             :                 bkt_clamp = uclamp_rq_max_value(rq, clamp_id, uc_se->value);
    1223             :                 WRITE_ONCE(uc_rq->value, bkt_clamp);
    1224             :         }
    1225             : }
    1226             : 
    1227             : static inline void uclamp_rq_inc(struct rq *rq, struct task_struct *p)
    1228             : {
    1229             :         enum uclamp_id clamp_id;
    1230             : 
    1231             :         /*
    1232             :          * Avoid any overhead until uclamp is actually used by the userspace.
    1233             :          *
    1234             :          * The condition is constructed such that a NOP is generated when
    1235             :          * sched_uclamp_used is disabled.
    1236             :          */
    1237             :         if (!static_branch_unlikely(&sched_uclamp_used))
    1238             :                 return;
    1239             : 
    1240             :         if (unlikely(!p->sched_class->uclamp_enabled))
    1241             :                 return;
    1242             : 
    1243             :         for_each_clamp_id(clamp_id)
    1244             :                 uclamp_rq_inc_id(rq, p, clamp_id);
    1245             : 
    1246             :         /* Reset clamp idle holding when there is one RUNNABLE task */
    1247             :         if (rq->uclamp_flags & UCLAMP_FLAG_IDLE)
    1248             :                 rq->uclamp_flags &= ~UCLAMP_FLAG_IDLE;
    1249             : }
    1250             : 
    1251             : static inline void uclamp_rq_dec(struct rq *rq, struct task_struct *p)
    1252             : {
    1253             :         enum uclamp_id clamp_id;
    1254             : 
    1255             :         /*
    1256             :          * Avoid any overhead until uclamp is actually used by the userspace.
    1257             :          *
    1258             :          * The condition is constructed such that a NOP is generated when
    1259             :          * sched_uclamp_used is disabled.
    1260             :          */
    1261             :         if (!static_branch_unlikely(&sched_uclamp_used))
    1262             :                 return;
    1263             : 
    1264             :         if (unlikely(!p->sched_class->uclamp_enabled))
    1265             :                 return;
    1266             : 
    1267             :         for_each_clamp_id(clamp_id)
    1268             :                 uclamp_rq_dec_id(rq, p, clamp_id);
    1269             : }
    1270             : 
    1271             : static inline void
    1272             : uclamp_update_active(struct task_struct *p, enum uclamp_id clamp_id)
    1273             : {
    1274             :         struct rq_flags rf;
    1275             :         struct rq *rq;
    1276             : 
    1277             :         /*
    1278             :          * Lock the task and the rq where the task is (or was) queued.
    1279             :          *
    1280             :          * We might lock the (previous) rq of a !RUNNABLE task, but that's the
    1281             :          * price to pay to safely serialize util_{min,max} updates with
    1282             :          * enqueues, dequeues and migration operations.
    1283             :          * This is the same locking schema used by __set_cpus_allowed_ptr().
    1284             :          */
    1285             :         rq = task_rq_lock(p, &rf);
    1286             : 
    1287             :         /*
    1288             :          * Setting the clamp bucket is serialized by task_rq_lock().
    1289             :          * If the task is not yet RUNNABLE and its task_struct is not
    1290             :          * affecting a valid clamp bucket, the next time it's enqueued,
    1291             :          * it will already see the updated clamp bucket value.
    1292             :          */
    1293             :         if (p->uclamp[clamp_id].active) {
    1294             :                 uclamp_rq_dec_id(rq, p, clamp_id);
    1295             :                 uclamp_rq_inc_id(rq, p, clamp_id);
    1296             :         }
    1297             : 
    1298             :         task_rq_unlock(rq, p, &rf);
    1299             : }
    1300             : 
    1301             : #ifdef CONFIG_UCLAMP_TASK_GROUP
    1302             : static inline void
    1303             : uclamp_update_active_tasks(struct cgroup_subsys_state *css,
    1304             :                            unsigned int clamps)
    1305             : {
    1306             :         enum uclamp_id clamp_id;
    1307             :         struct css_task_iter it;
    1308             :         struct task_struct *p;
    1309             : 
    1310             :         css_task_iter_start(css, 0, &it);
    1311             :         while ((p = css_task_iter_next(&it))) {
    1312             :                 for_each_clamp_id(clamp_id) {
    1313             :                         if ((0x1 << clamp_id) & clamps)
    1314             :                                 uclamp_update_active(p, clamp_id);
    1315             :                 }
    1316             :         }
    1317             :         css_task_iter_end(&it);
    1318             : }
    1319             : 
    1320             : static void cpu_util_update_eff(struct cgroup_subsys_state *css);
    1321             : static void uclamp_update_root_tg(void)
    1322             : {
    1323             :         struct task_group *tg = &root_task_group;
    1324             : 
    1325             :         uclamp_se_set(&tg->uclamp_req[UCLAMP_MIN],
    1326             :                       sysctl_sched_uclamp_util_min, false);
    1327             :         uclamp_se_set(&tg->uclamp_req[UCLAMP_MAX],
    1328             :                       sysctl_sched_uclamp_util_max, false);
    1329             : 
    1330             :         rcu_read_lock();
    1331             :         cpu_util_update_eff(&root_task_group.css);
    1332             :         rcu_read_unlock();
    1333             : }
    1334             : #else
    1335             : static void uclamp_update_root_tg(void) { }
    1336             : #endif
    1337             : 
    1338             : int sysctl_sched_uclamp_handler(struct ctl_table *table, int write,
    1339             :                                 void *buffer, size_t *lenp, loff_t *ppos)
    1340             : {
    1341             :         bool update_root_tg = false;
    1342             :         int old_min, old_max, old_min_rt;
    1343             :         int result;
    1344             : 
    1345             :         mutex_lock(&uclamp_mutex);
    1346             :         old_min = sysctl_sched_uclamp_util_min;
    1347             :         old_max = sysctl_sched_uclamp_util_max;
    1348             :         old_min_rt = sysctl_sched_uclamp_util_min_rt_default;
    1349             : 
    1350             :         result = proc_dointvec(table, write, buffer, lenp, ppos);
    1351             :         if (result)
    1352             :                 goto undo;
    1353             :         if (!write)
    1354             :                 goto done;
    1355             : 
    1356             :         if (sysctl_sched_uclamp_util_min > sysctl_sched_uclamp_util_max ||
    1357             :             sysctl_sched_uclamp_util_max > SCHED_CAPACITY_SCALE      ||
    1358             :             sysctl_sched_uclamp_util_min_rt_default > SCHED_CAPACITY_SCALE) {
    1359             : 
    1360             :                 result = -EINVAL;
    1361             :                 goto undo;
    1362             :         }
    1363             : 
    1364             :         if (old_min != sysctl_sched_uclamp_util_min) {
    1365             :                 uclamp_se_set(&uclamp_default[UCLAMP_MIN],
    1366             :                               sysctl_sched_uclamp_util_min, false);
    1367             :                 update_root_tg = true;
    1368             :         }
    1369             :         if (old_max != sysctl_sched_uclamp_util_max) {
    1370             :                 uclamp_se_set(&uclamp_default[UCLAMP_MAX],
    1371             :                               sysctl_sched_uclamp_util_max, false);
    1372             :                 update_root_tg = true;
    1373             :         }
    1374             : 
    1375             :         if (update_root_tg) {
    1376             :                 static_branch_enable(&sched_uclamp_used);
    1377             :                 uclamp_update_root_tg();
    1378             :         }
    1379             : 
    1380             :         if (old_min_rt != sysctl_sched_uclamp_util_min_rt_default) {
    1381             :                 static_branch_enable(&sched_uclamp_used);
    1382             :                 uclamp_sync_util_min_rt_default();
    1383             :         }
    1384             : 
    1385             :         /*
    1386             :          * We update all RUNNABLE tasks only when task groups are in use.
    1387             :          * Otherwise, keep it simple and do just a lazy update at each next
    1388             :          * task enqueue time.
    1389             :          */
    1390             : 
    1391             :         goto done;
    1392             : 
    1393             : undo:
    1394             :         sysctl_sched_uclamp_util_min = old_min;
    1395             :         sysctl_sched_uclamp_util_max = old_max;
    1396             :         sysctl_sched_uclamp_util_min_rt_default = old_min_rt;
    1397             : done:
    1398             :         mutex_unlock(&uclamp_mutex);
    1399             : 
    1400             :         return result;
    1401             : }
    1402             : 
    1403             : static int uclamp_validate(struct task_struct *p,
    1404             :                            const struct sched_attr *attr)
    1405             : {
    1406             :         int util_min = p->uclamp_req[UCLAMP_MIN].value;
    1407             :         int util_max = p->uclamp_req[UCLAMP_MAX].value;
    1408             : 
    1409             :         if (attr->sched_flags & SCHED_FLAG_UTIL_CLAMP_MIN) {
    1410             :                 util_min = attr->sched_util_min;
    1411             : 
    1412             :                 if (util_min + 1 > SCHED_CAPACITY_SCALE + 1)
    1413             :                         return -EINVAL;
    1414             :         }
    1415             : 
    1416             :         if (attr->sched_flags & SCHED_FLAG_UTIL_CLAMP_MAX) {
    1417             :                 util_max = attr->sched_util_max;
    1418             : 
    1419             :                 if (util_max + 1 > SCHED_CAPACITY_SCALE + 1)
    1420             :                         return -EINVAL;
    1421             :         }
    1422             : 
    1423             :         if (util_min != -1 && util_max != -1 && util_min > util_max)
    1424             :                 return -EINVAL;
    1425             : 
    1426             :         /*
    1427             :          * We have valid uclamp attributes; make sure uclamp is enabled.
    1428             :          *
    1429             :          * We need to do that here, because enabling static branches is a
    1430             :          * blocking operation which obviously cannot be done while holding
    1431             :          * scheduler locks.
    1432             :          */
    1433             :         static_branch_enable(&sched_uclamp_used);
    1434             : 
    1435             :         return 0;
    1436             : }
    1437             : 
    1438             : static bool uclamp_reset(const struct sched_attr *attr,
    1439             :                          enum uclamp_id clamp_id,
    1440             :                          struct uclamp_se *uc_se)
    1441             : {
    1442             :         /* Reset on sched class change for a non user-defined clamp value. */
    1443             :         if (likely(!(attr->sched_flags & SCHED_FLAG_UTIL_CLAMP)) &&
    1444             :             !uc_se->user_defined)
    1445             :                 return true;
    1446             : 
    1447             :         /* Reset on sched_util_{min,max} == -1. */
    1448             :         if (clamp_id == UCLAMP_MIN &&
    1449             :             attr->sched_flags & SCHED_FLAG_UTIL_CLAMP_MIN &&
    1450             :             attr->sched_util_min == -1) {
    1451             :                 return true;
    1452             :         }
    1453             : 
    1454             :         if (clamp_id == UCLAMP_MAX &&
    1455             :             attr->sched_flags & SCHED_FLAG_UTIL_CLAMP_MAX &&
    1456             :             attr->sched_util_max == -1) {
    1457             :                 return true;
    1458             :         }
    1459             : 
    1460             :         return false;
    1461             : }
    1462             : 
    1463             : static void __setscheduler_uclamp(struct task_struct *p,
    1464             :                                   const struct sched_attr *attr)
    1465             : {
    1466             :         enum uclamp_id clamp_id;
    1467             : 
    1468             :         for_each_clamp_id(clamp_id) {
    1469             :                 struct uclamp_se *uc_se = &p->uclamp_req[clamp_id];
    1470             :                 unsigned int value;
    1471             : 
    1472             :                 if (!uclamp_reset(attr, clamp_id, uc_se))
    1473             :                         continue;
    1474             : 
    1475             :                 /*
    1476             :                  * RT by default have a 100% boost value that could be modified
    1477             :                  * at runtime.
    1478             :                  */
    1479             :                 if (unlikely(rt_task(p) && clamp_id == UCLAMP_MIN))
    1480             :                         value = sysctl_sched_uclamp_util_min_rt_default;
    1481             :                 else
    1482             :                         value = uclamp_none(clamp_id);
    1483             : 
    1484             :                 uclamp_se_set(uc_se, value, false);
    1485             : 
    1486             :         }
    1487             : 
    1488             :         if (likely(!(attr->sched_flags & SCHED_FLAG_UTIL_CLAMP)))
    1489             :                 return;
    1490             : 
    1491             :         if (attr->sched_flags & SCHED_FLAG_UTIL_CLAMP_MIN &&
    1492             :             attr->sched_util_min != -1) {
    1493             :                 uclamp_se_set(&p->uclamp_req[UCLAMP_MIN],
    1494             :                               attr->sched_util_min, true);
    1495             :         }
    1496             : 
    1497             :         if (attr->sched_flags & SCHED_FLAG_UTIL_CLAMP_MAX &&
    1498             :             attr->sched_util_max != -1) {
    1499             :                 uclamp_se_set(&p->uclamp_req[UCLAMP_MAX],
    1500             :                               attr->sched_util_max, true);
    1501             :         }
    1502             : }
    1503             : 
    1504             : static void uclamp_fork(struct task_struct *p)
    1505             : {
    1506             :         enum uclamp_id clamp_id;
    1507             : 
    1508             :         /*
    1509             :          * We don't need to hold task_rq_lock() when updating p->uclamp_* here
    1510             :          * as the task is still at its early fork stages.
    1511             :          */
    1512             :         for_each_clamp_id(clamp_id)
    1513             :                 p->uclamp[clamp_id].active = false;
    1514             : 
    1515             :         if (likely(!p->sched_reset_on_fork))
    1516             :                 return;
    1517             : 
    1518             :         for_each_clamp_id(clamp_id) {
    1519             :                 uclamp_se_set(&p->uclamp_req[clamp_id],
    1520             :                               uclamp_none(clamp_id), false);
    1521             :         }
    1522             : }
    1523             : 
    1524             : static void uclamp_post_fork(struct task_struct *p)
    1525             : {
    1526             :         uclamp_update_util_min_rt_default(p);
    1527             : }
    1528             : 
    1529             : static void __init init_uclamp_rq(struct rq *rq)
    1530             : {
    1531             :         enum uclamp_id clamp_id;
    1532             :         struct uclamp_rq *uc_rq = rq->uclamp;
    1533             : 
    1534             :         for_each_clamp_id(clamp_id) {
    1535             :                 uc_rq[clamp_id] = (struct uclamp_rq) {
    1536             :                         .value = uclamp_none(clamp_id)
    1537             :                 };
    1538             :         }
    1539             : 
    1540             :         rq->uclamp_flags = 0;
    1541             : }
    1542             : 
    1543             : static void __init init_uclamp(void)
    1544             : {
    1545             :         struct uclamp_se uc_max = {};
    1546             :         enum uclamp_id clamp_id;
    1547             :         int cpu;
    1548             : 
    1549             :         for_each_possible_cpu(cpu)
    1550             :                 init_uclamp_rq(cpu_rq(cpu));
    1551             : 
    1552             :         for_each_clamp_id(clamp_id) {
    1553             :                 uclamp_se_set(&init_task.uclamp_req[clamp_id],
    1554             :                               uclamp_none(clamp_id), false);
    1555             :         }
    1556             : 
    1557             :         /* System defaults allow max clamp values for both indexes */
    1558             :         uclamp_se_set(&uc_max, uclamp_none(UCLAMP_MAX), false);
    1559             :         for_each_clamp_id(clamp_id) {
    1560             :                 uclamp_default[clamp_id] = uc_max;
    1561             : #ifdef CONFIG_UCLAMP_TASK_GROUP
    1562             :                 root_task_group.uclamp_req[clamp_id] = uc_max;
    1563             :                 root_task_group.uclamp[clamp_id] = uc_max;
    1564             : #endif
    1565             :         }
    1566             : }
    1567             : 
    1568             : #else /* CONFIG_UCLAMP_TASK */
    1569       15735 : static inline void uclamp_rq_inc(struct rq *rq, struct task_struct *p) { }
    1570       15739 : static inline void uclamp_rq_dec(struct rq *rq, struct task_struct *p) { }
    1571             : static inline int uclamp_validate(struct task_struct *p,
    1572             :                                   const struct sched_attr *attr)
    1573             : {
    1574             :         return -EOPNOTSUPP;
    1575             : }
    1576           4 : static void __setscheduler_uclamp(struct task_struct *p,
    1577           4 :                                   const struct sched_attr *attr) { }
    1578         980 : static inline void uclamp_fork(struct task_struct *p) { }
    1579         980 : static inline void uclamp_post_fork(struct task_struct *p) { }
    1580           1 : static inline void init_uclamp(void) { }
    1581             : #endif /* CONFIG_UCLAMP_TASK */
    1582             : 
    1583       15735 : static inline void enqueue_task(struct rq *rq, struct task_struct *p, int flags)
    1584             : {
    1585       15735 :         if (!(flags & ENQUEUE_NOCLOCK))
    1586          31 :                 update_rq_clock(rq);
    1587             : 
    1588       15735 :         if (!(flags & ENQUEUE_RESTORE)) {
    1589       15723 :                 sched_info_queued(rq, p);
    1590       15723 :                 psi_enqueue(p, flags & ENQUEUE_WAKEUP);
    1591             :         }
    1592             : 
    1593       15735 :         uclamp_rq_inc(rq, p);
    1594       15735 :         p->sched_class->enqueue_task(rq, p, flags);
    1595       15737 : }
    1596             : 
    1597       15738 : static inline void dequeue_task(struct rq *rq, struct task_struct *p, int flags)
    1598             : {
    1599       15738 :         if (!(flags & DEQUEUE_NOCLOCK))
    1600           0 :                 update_rq_clock(rq);
    1601             : 
    1602       15738 :         if (!(flags & DEQUEUE_SAVE)) {
    1603       15722 :                 sched_info_dequeued(rq, p);
    1604       15722 :                 psi_dequeue(p, flags & DEQUEUE_SLEEP);
    1605             :         }
    1606             : 
    1607       15739 :         uclamp_rq_dec(rq, p);
    1608       15739 :         p->sched_class->dequeue_task(rq, p, flags);
    1609       15737 : }
    1610             : 
    1611       15720 : void activate_task(struct rq *rq, struct task_struct *p, int flags)
    1612             : {
    1613         853 :         enqueue_task(rq, p, flags);
    1614             : 
    1615       15722 :         p->on_rq = TASK_ON_RQ_QUEUED;
    1616         853 : }
    1617             : 
    1618       15722 : void deactivate_task(struct rq *rq, struct task_struct *p, int flags)
    1619             : {
    1620         853 :         p->on_rq = (flags & DEQUEUE_SLEEP) ? 0 : TASK_ON_RQ_MIGRATING;
    1621             : 
    1622         853 :         dequeue_task(rq, p, flags);
    1623         854 : }
    1624             : 
    1625             : /*
    1626             :  * __normal_prio - return the priority that is based on the static prio
    1627             :  */
    1628          21 : static inline int __normal_prio(struct task_struct *p)
    1629             : {
    1630          21 :         return p->static_prio;
    1631             : }
    1632             : 
    1633             : /*
    1634             :  * Calculate the expected normal priority: i.e. priority
    1635             :  * without taking RT-inheritance into account. Might be
    1636             :  * boosted by interactivity modifiers. Changes upon fork,
    1637             :  * setprio syscalls, and whenever the interactivity
    1638             :  * estimator recalculates.
    1639             :  */
    1640          29 : static inline int normal_prio(struct task_struct *p)
    1641             : {
    1642          29 :         int prio;
    1643             : 
    1644          29 :         if (task_has_dl_policy(p))
    1645             :                 prio = MAX_DL_PRIO-1;
    1646          29 :         else if (task_has_rt_policy(p))
    1647           8 :                 prio = MAX_RT_PRIO-1 - p->rt_priority;
    1648             :         else
    1649          21 :                 prio = __normal_prio(p);
    1650          29 :         return prio;
    1651             : }
    1652             : 
    1653             : /*
    1654             :  * Calculate the current priority, i.e. the priority
    1655             :  * taken into account by the scheduler. This value might
    1656             :  * be boosted by RT tasks, or might be boosted by
    1657             :  * interactivity modifiers. Will be RT if the task got
    1658             :  * RT-boosted. If not then it returns p->normal_prio.
    1659             :  */
    1660          21 : static int effective_prio(struct task_struct *p)
    1661             : {
    1662          21 :         p->normal_prio = normal_prio(p);
    1663             :         /*
    1664             :          * If we are RT tasks or we were boosted to RT priority,
    1665             :          * keep the priority unchanged. Otherwise, update priority
    1666             :          * to the normal priority:
    1667             :          */
    1668          21 :         if (!rt_prio(p->prio))
    1669          21 :                 return p->normal_prio;
    1670             :         return p->prio;
    1671             : }
    1672             : 
    1673             : /**
    1674             :  * task_curr - is this task currently executing on a CPU?
    1675             :  * @p: the task in question.
    1676             :  *
    1677             :  * Return: 1 if the task is currently executing. 0 otherwise.
    1678             :  */
    1679         546 : inline int task_curr(const struct task_struct *p)
    1680             : {
    1681          60 :         return cpu_curr(task_cpu(p)) == p;
    1682             : }
    1683             : 
    1684             : /*
    1685             :  * switched_from, switched_to and prio_changed must _NOT_ drop rq->lock,
    1686             :  * use the balance_callback list if you want balancing.
    1687             :  *
    1688             :  * this means any call to check_class_changed() must be followed by a call to
    1689             :  * balance_callback().
    1690             :  */
    1691           4 : static inline void check_class_changed(struct rq *rq, struct task_struct *p,
    1692             :                                        const struct sched_class *prev_class,
    1693             :                                        int oldprio)
    1694             : {
    1695           4 :         if (prev_class != p->sched_class) {
    1696           4 :                 if (prev_class->switched_from)
    1697           4 :                         prev_class->switched_from(rq, p);
    1698             : 
    1699           4 :                 p->sched_class->switched_to(rq, p);
    1700           0 :         } else if (oldprio != p->prio || dl_task(p))
    1701           0 :                 p->sched_class->prio_changed(rq, p, oldprio);
    1702           4 : }
    1703             : 
    1704       15885 : void check_preempt_curr(struct rq *rq, struct task_struct *p, int flags)
    1705             : {
    1706       15885 :         if (p->sched_class == rq->curr->sched_class)
    1707        8352 :                 rq->curr->sched_class->check_preempt_curr(rq, p, flags);
    1708        7533 :         else if (p->sched_class > rq->curr->sched_class)
    1709        7532 :                 resched_curr(rq);
    1710             : 
    1711             :         /*
    1712             :          * A queue event has occurred, and we're going to schedule.  In
    1713             :          * this case, we can save a useless back to back clock update.
    1714             :          */
    1715       15886 :         if (task_on_rq_queued(rq->curr) && test_tsk_need_resched(rq->curr))
    1716       12988 :                 rq_clock_skip_update(rq);
    1717       15883 : }
    1718             : 
    1719             : #ifdef CONFIG_SMP
    1720             : 
    1721             : static void
    1722             : __do_set_cpus_allowed(struct task_struct *p, const struct cpumask *new_mask, u32 flags);
    1723             : 
    1724             : static int __set_cpus_allowed_ptr(struct task_struct *p,
    1725             :                                   const struct cpumask *new_mask,
    1726             :                                   u32 flags);
    1727             : 
    1728       26513 : static void migrate_disable_switch(struct rq *rq, struct task_struct *p)
    1729             : {
    1730       26513 :         if (likely(!p->migration_disabled))
    1731             :                 return;
    1732             : 
    1733           0 :         if (p->cpus_ptr != &p->cpus_mask)
    1734             :                 return;
    1735             : 
    1736             :         /*
    1737             :          * Violates locking rules! see comment in __do_set_cpus_allowed().
    1738             :          */
    1739           0 :         __do_set_cpus_allowed(p, cpumask_of(rq->cpu), SCA_MIGRATE_DISABLE);
    1740             : }
    1741             : 
    1742        1068 : void migrate_disable(void)
    1743             : {
    1744        1068 :         struct task_struct *p = current;
    1745             : 
    1746        1068 :         if (p->migration_disabled) {
    1747           0 :                 p->migration_disabled++;
    1748           0 :                 return;
    1749             :         }
    1750             : 
    1751        1068 :         preempt_disable();
    1752        1068 :         this_rq()->nr_pinned++;
    1753        1068 :         p->migration_disabled = 1;
    1754        1068 :         preempt_enable();
    1755             : }
    1756             : EXPORT_SYMBOL_GPL(migrate_disable);
    1757             : 
    1758        1068 : void migrate_enable(void)
    1759             : {
    1760        1068 :         struct task_struct *p = current;
    1761             : 
    1762        1068 :         if (p->migration_disabled > 1) {
    1763           0 :                 p->migration_disabled--;
    1764           0 :                 return;
    1765             :         }
    1766             : 
    1767             :         /*
    1768             :          * Ensure stop_task runs either before or after this, and that
    1769             :          * __set_cpus_allowed_ptr(SCA_MIGRATE_ENABLE) doesn't schedule().
    1770             :          */
    1771        1068 :         preempt_disable();
    1772        1068 :         if (p->cpus_ptr != &p->cpus_mask)
    1773           0 :                 __set_cpus_allowed_ptr(p, &p->cpus_mask, SCA_MIGRATE_ENABLE);
    1774             :         /*
    1775             :          * Mustn't clear migration_disabled() until cpus_ptr points back at the
    1776             :          * regular cpus_mask, otherwise things that race (eg.
    1777             :          * select_fallback_rq) get confused.
    1778             :          */
    1779        1068 :         barrier();
    1780        1068 :         p->migration_disabled = 0;
    1781        1068 :         this_rq()->nr_pinned--;
    1782        1068 :         preempt_enable();
    1783             : }
    1784             : EXPORT_SYMBOL_GPL(migrate_enable);
    1785             : 
    1786           0 : static inline bool rq_has_pinned_tasks(struct rq *rq)
    1787             : {
    1788           0 :         return rq->nr_pinned;
    1789             : }
    1790             : 
    1791             : /*
    1792             :  * Per-CPU kthreads are allowed to run on !active && online CPUs, see
    1793             :  * __set_cpus_allowed_ptr() and select_fallback_rq().
    1794             :  */
    1795       14849 : static inline bool is_cpu_allowed(struct task_struct *p, int cpu)
    1796             : {
    1797             :         /* When not in the task's cpumask, no point in looking further. */
    1798       14849 :         if (!cpumask_test_cpu(cpu, p->cpus_ptr))
    1799             :                 return false;
    1800             : 
    1801             :         /* migrate_disabled() must be allowed to finish. */
    1802       14850 :         if (is_migration_disabled(p))
    1803           0 :                 return cpu_online(cpu);
    1804             : 
    1805             :         /* Non kernel threads are not allowed during either online or offline. */
    1806       14850 :         if (!(p->flags & PF_KTHREAD))
    1807        6614 :                 return cpu_active(cpu);
    1808             : 
    1809             :         /* KTHREAD_IS_PER_CPU is always allowed. */
    1810        8236 :         if (kthread_is_per_cpu(p))
    1811        3711 :                 return cpu_online(cpu);
    1812             : 
    1813             :         /* Regular kernel threads don't get to stay during offline. */
    1814        4523 :         if (cpu_rq(cpu)->balance_push)
    1815             :                 return false;
    1816             : 
    1817             :         /* But are allowed during online. */
    1818        4525 :         return cpu_online(cpu);
    1819             : }
    1820             : 
    1821             : /*
    1822             :  * This is how migration works:
    1823             :  *
    1824             :  * 1) we invoke migration_cpu_stop() on the target CPU using
    1825             :  *    stop_one_cpu().
    1826             :  * 2) stopper starts to run (implicitly forcing the migrated thread
    1827             :  *    off the CPU)
    1828             :  * 3) it checks whether the migrated task is still in the wrong runqueue.
    1829             :  * 4) if it's in the wrong runqueue then the migration thread removes
    1830             :  *    it and puts it into the right queue.
    1831             :  * 5) stopper completes and stop_one_cpu() returns and the migration
    1832             :  *    is done.
    1833             :  */
    1834             : 
    1835             : /*
    1836             :  * move_queued_task - move a queued task to new rq.
    1837             :  *
    1838             :  * Returns (locked) new rq. Old rq's lock is released.
    1839             :  */
    1840          31 : static struct rq *move_queued_task(struct rq *rq, struct rq_flags *rf,
    1841             :                                    struct task_struct *p, int new_cpu)
    1842             : {
    1843          62 :         lockdep_assert_held(&rq->lock);
    1844             : 
    1845          31 :         deactivate_task(rq, p, DEQUEUE_NOCLOCK);
    1846          31 :         set_task_cpu(p, new_cpu);
    1847          31 :         rq_unlock(rq, rf);
    1848             : 
    1849          31 :         rq = cpu_rq(new_cpu);
    1850             : 
    1851          31 :         rq_lock(rq, rf);
    1852          31 :         BUG_ON(task_cpu(p) != new_cpu);
    1853          31 :         activate_task(rq, p, 0);
    1854          31 :         check_preempt_curr(rq, p, 0);
    1855             : 
    1856          31 :         return rq;
    1857             : }
    1858             : 
    1859             : struct migration_arg {
    1860             :         struct task_struct              *task;
    1861             :         int                             dest_cpu;
    1862             :         struct set_affinity_pending     *pending;
    1863             : };
    1864             : 
    1865             : /*
    1866             :  * @refs: number of wait_for_completion()
    1867             :  * @stop_pending: is @stop_work in use
    1868             :  */
    1869             : struct set_affinity_pending {
    1870             :         refcount_t              refs;
    1871             :         unsigned int            stop_pending;
    1872             :         struct completion       done;
    1873             :         struct cpu_stop_work    stop_work;
    1874             :         struct migration_arg    arg;
    1875             : };
    1876             : 
    1877             : /*
    1878             :  * Move (not current) task off this CPU, onto the destination CPU. We're doing
    1879             :  * this because either it can't run here any more (set_cpus_allowed()
    1880             :  * away from this CPU, or CPU going down), or because we're
    1881             :  * attempting to rebalance this task on exec (sched_exec).
    1882             :  *
    1883             :  * So we race with normal scheduler movements, but that's OK, as long
    1884             :  * as the task is no longer on this CPU.
    1885             :  */
    1886          31 : static struct rq *__migrate_task(struct rq *rq, struct rq_flags *rf,
    1887             :                                  struct task_struct *p, int dest_cpu)
    1888             : {
    1889             :         /* Affinity changed (again). */
    1890          31 :         if (!is_cpu_allowed(p, dest_cpu))
    1891             :                 return rq;
    1892             : 
    1893          31 :         update_rq_clock(rq);
    1894          31 :         rq = move_queued_task(rq, rf, p, dest_cpu);
    1895             : 
    1896          31 :         return rq;
    1897             : }
    1898             : 
    1899             : /*
    1900             :  * migration_cpu_stop - this will be executed by a highprio stopper thread
    1901             :  * and performs thread migration by bumping thread off CPU then
    1902             :  * 'pushing' onto another runqueue.
    1903             :  */
    1904          31 : static int migration_cpu_stop(void *data)
    1905             : {
    1906          31 :         struct migration_arg *arg = data;
    1907          31 :         struct set_affinity_pending *pending = arg->pending;
    1908          31 :         struct task_struct *p = arg->task;
    1909          31 :         int dest_cpu = arg->dest_cpu;
    1910          31 :         struct rq *rq = this_rq();
    1911          31 :         bool complete = false;
    1912          31 :         struct rq_flags rf;
    1913             : 
    1914             :         /*
    1915             :          * The original target CPU might have gone down and we might
    1916             :          * be on another CPU but it doesn't matter.
    1917             :          */
    1918          62 :         local_irq_save(rf.flags);
    1919             :         /*
    1920             :          * We need to explicitly wake pending tasks before running
    1921             :          * __migrate_task() such that we will not miss enforcing cpus_ptr
    1922             :          * during wakeups, see set_cpus_allowed_ptr()'s TASK_WAKING test.
    1923             :          */
    1924          31 :         flush_smp_call_function_from_idle();
    1925             : 
    1926          31 :         raw_spin_lock(&p->pi_lock);
    1927          31 :         rq_lock(rq, &rf);
    1928             : 
    1929             :         /*
    1930             :          * If task_rq(p) != rq, it cannot be migrated here, because we're
    1931             :          * holding rq->lock, if p->on_rq == 0 it cannot get enqueued because
    1932             :          * we're holding p->pi_lock.
    1933             :          */
    1934          31 :         if (task_rq(p) == rq) {
    1935          31 :                 if (is_migration_disabled(p))
    1936           0 :                         goto out;
    1937             : 
    1938          31 :                 if (pending) {
    1939           0 :                         if (p->migration_pending == pending)
    1940           0 :                                 p->migration_pending = NULL;
    1941             :                         complete = true;
    1942             :                 }
    1943             : 
    1944          31 :                 if (dest_cpu < 0) {
    1945           0 :                         if (cpumask_test_cpu(task_cpu(p), &p->cpus_mask))
    1946           0 :                                 goto out;
    1947             : 
    1948           0 :                         dest_cpu = cpumask_any_distribute(&p->cpus_mask);
    1949             :                 }
    1950             : 
    1951          31 :                 if (task_on_rq_queued(p))
    1952          31 :                         rq = __migrate_task(rq, &rf, p, dest_cpu);
    1953             :                 else
    1954           0 :                         p->wake_cpu = dest_cpu;
    1955             : 
    1956             :                 /*
    1957             :                  * XXX __migrate_task() can fail, at which point we might end
    1958             :                  * up running on a dodgy CPU, AFAICT this can only happen
    1959             :                  * during CPU hotplug, at which point we'll get pushed out
    1960             :                  * anyway, so it's probably not a big deal.
    1961             :                  */
    1962             : 
    1963           0 :         } else if (pending) {
    1964             :                 /*
    1965             :                  * This happens when we get migrated between migrate_enable()'s
    1966             :                  * preempt_enable() and scheduling the stopper task. At that
    1967             :                  * point we're a regular task again and not current anymore.
    1968             :                  *
    1969             :                  * A !PREEMPT kernel has a giant hole here, which makes it far
    1970             :                  * more likely.
    1971             :                  */
    1972             : 
    1973             :                 /*
    1974             :                  * The task moved before the stopper got to run. We're holding
    1975             :                  * ->pi_lock, so the allowed mask is stable - if it got
    1976             :                  * somewhere allowed, we're done.
    1977             :                  */
    1978           0 :                 if (cpumask_test_cpu(task_cpu(p), p->cpus_ptr)) {
    1979           0 :                         if (p->migration_pending == pending)
    1980           0 :                                 p->migration_pending = NULL;
    1981           0 :                         complete = true;
    1982           0 :                         goto out;
    1983             :                 }
    1984             : 
    1985             :                 /*
    1986             :                  * When migrate_enable() hits a rq mis-match we can't reliably
    1987             :                  * determine is_migration_disabled() and so have to chase after
    1988             :                  * it.
    1989             :                  */
    1990           0 :                 WARN_ON_ONCE(!pending->stop_pending);
    1991           0 :                 task_rq_unlock(rq, p, &rf);
    1992           0 :                 stop_one_cpu_nowait(task_cpu(p), migration_cpu_stop,
    1993           0 :                                     &pending->arg, &pending->stop_work);
    1994           0 :                 return 0;
    1995             :         }
    1996           0 : out:
    1997          31 :         if (pending)
    1998           0 :                 pending->stop_pending = false;
    1999          31 :         task_rq_unlock(rq, p, &rf);
    2000             : 
    2001          31 :         if (complete)
    2002           0 :                 complete_all(&pending->done);
    2003             : 
    2004             :         return 0;
    2005             : }
    2006             : 
    2007           0 : int push_cpu_stop(void *arg)
    2008             : {
    2009           0 :         struct rq *lowest_rq = NULL, *rq = this_rq();
    2010           0 :         struct task_struct *p = arg;
    2011             : 
    2012           0 :         raw_spin_lock_irq(&p->pi_lock);
    2013           0 :         raw_spin_lock(&rq->lock);
    2014             : 
    2015           0 :         if (task_rq(p) != rq)
    2016           0 :                 goto out_unlock;
    2017             : 
    2018           0 :         if (is_migration_disabled(p)) {
    2019           0 :                 p->migration_flags |= MDF_PUSH;
    2020           0 :                 goto out_unlock;
    2021             :         }
    2022             : 
    2023           0 :         p->migration_flags &= ~MDF_PUSH;
    2024             : 
    2025           0 :         if (p->sched_class->find_lock_rq)
    2026           0 :                 lowest_rq = p->sched_class->find_lock_rq(p, rq);
    2027             : 
    2028           0 :         if (!lowest_rq)
    2029           0 :                 goto out_unlock;
    2030             : 
    2031             :         // XXX validate p is still the highest prio task
    2032           0 :         if (task_rq(p) == rq) {
    2033           0 :                 deactivate_task(rq, p, 0);
    2034           0 :                 set_task_cpu(p, lowest_rq->cpu);
    2035           0 :                 activate_task(lowest_rq, p, 0);
    2036           0 :                 resched_curr(lowest_rq);
    2037             :         }
    2038             : 
    2039           0 :         double_unlock_balance(rq, lowest_rq);
    2040             : 
    2041           0 : out_unlock:
    2042           0 :         rq->push_busy = false;
    2043           0 :         raw_spin_unlock(&rq->lock);
    2044           0 :         raw_spin_unlock_irq(&p->pi_lock);
    2045             : 
    2046           0 :         put_task_struct(p);
    2047           0 :         return 0;
    2048             : }
    2049             : 
    2050             : /*
    2051             :  * sched_class::set_cpus_allowed must do the below, but is not required to
    2052             :  * actually call this function.
    2053             :  */
    2054          88 : void set_cpus_allowed_common(struct task_struct *p, const struct cpumask *new_mask, u32 flags)
    2055             : {
    2056          78 :         if (flags & (SCA_MIGRATE_ENABLE | SCA_MIGRATE_DISABLE)) {
    2057           0 :                 p->cpus_ptr = new_mask;
    2058           0 :                 return;
    2059             :         }
    2060             : 
    2061          88 :         cpumask_copy(&p->cpus_mask, new_mask);
    2062          78 :         p->nr_cpus_allowed = cpumask_weight(new_mask);
    2063             : }
    2064             : 
    2065             : static void
    2066          78 : __do_set_cpus_allowed(struct task_struct *p, const struct cpumask *new_mask, u32 flags)
    2067             : {
    2068          78 :         struct rq *rq = task_rq(p);
    2069          78 :         bool queued, running;
    2070             : 
    2071             :         /*
    2072             :          * This here violates the locking rules for affinity, since we're only
    2073             :          * supposed to change these variables while holding both rq->lock and
    2074             :          * p->pi_lock.
    2075             :          *
    2076             :          * HOWEVER, it magically works, because ttwu() is the only code that
    2077             :          * accesses these variables under p->pi_lock and only does so after
    2078             :          * smp_cond_load_acquire(&p->on_cpu, !VAL), and we're in __schedule()
    2079             :          * before finish_task().
    2080             :          *
    2081             :          * XXX do further audits, this smells like something putrid.
    2082             :          */
    2083          78 :         if (flags & SCA_MIGRATE_DISABLE)
    2084             :                 SCHED_WARN_ON(!p->on_cpu);
    2085             :         else
    2086         156 :                 lockdep_assert_held(&p->pi_lock);
    2087             : 
    2088          78 :         queued = task_on_rq_queued(p);
    2089          78 :         running = task_current(rq, p);
    2090             : 
    2091          78 :         if (queued) {
    2092             :                 /*
    2093             :                  * Because __kthread_bind() calls this on blocked tasks without
    2094             :                  * holding rq->lock.
    2095             :                  */
    2096           4 :                 lockdep_assert_held(&rq->lock);
    2097           2 :                 dequeue_task(rq, p, DEQUEUE_SAVE | DEQUEUE_NOCLOCK);
    2098             :         }
    2099          78 :         if (running)
    2100           2 :                 put_prev_task(rq, p);
    2101             : 
    2102          78 :         p->sched_class->set_cpus_allowed(p, new_mask, flags);
    2103             : 
    2104          78 :         if (queued)
    2105           2 :                 enqueue_task(rq, p, ENQUEUE_RESTORE | ENQUEUE_NOCLOCK);
    2106          78 :         if (running)
    2107           2 :                 set_next_task(rq, p);
    2108          78 : }
    2109             : 
    2110          67 : void do_set_cpus_allowed(struct task_struct *p, const struct cpumask *new_mask)
    2111             : {
    2112          52 :         __do_set_cpus_allowed(p, new_mask, 0);
    2113          52 : }
    2114             : 
    2115             : /*
    2116             :  * This function is wildly self concurrent; here be dragons.
    2117             :  *
    2118             :  *
    2119             :  * When given a valid mask, __set_cpus_allowed_ptr() must block until the
    2120             :  * designated task is enqueued on an allowed CPU. If that task is currently
    2121             :  * running, we have to kick it out using the CPU stopper.
    2122             :  *
    2123             :  * Migrate-Disable comes along and tramples all over our nice sandcastle.
    2124             :  * Consider:
    2125             :  *
    2126             :  *     Initial conditions: P0->cpus_mask = [0, 1]
    2127             :  *
    2128             :  *     P0@CPU0                  P1
    2129             :  *
    2130             :  *     migrate_disable();
    2131             :  *     <preempted>
    2132             :  *                              set_cpus_allowed_ptr(P0, [1]);
    2133             :  *
    2134             :  * P1 *cannot* return from this set_cpus_allowed_ptr() call until P0 executes
    2135             :  * its outermost migrate_enable() (i.e. it exits its Migrate-Disable region).
    2136             :  * This means we need the following scheme:
    2137             :  *
    2138             :  *     P0@CPU0                  P1
    2139             :  *
    2140             :  *     migrate_disable();
    2141             :  *     <preempted>
    2142             :  *                              set_cpus_allowed_ptr(P0, [1]);
    2143             :  *                                <blocks>
    2144             :  *     <resumes>
    2145             :  *     migrate_enable();
    2146             :  *       __set_cpus_allowed_ptr();
    2147             :  *       <wakes local stopper>
    2148             :  *                         `--> <woken on migration completion>
    2149             :  *
    2150             :  * Now the fun stuff: there may be several P1-like tasks, i.e. multiple
    2151             :  * concurrent set_cpus_allowed_ptr(P0, [*]) calls. CPU affinity changes of any
    2152             :  * task p are serialized by p->pi_lock, which we can leverage: the one that
    2153             :  * should come into effect at the end of the Migrate-Disable region is the last
    2154             :  * one. This means we only need to track a single cpumask (i.e. p->cpus_mask),
    2155             :  * but we still need to properly signal those waiting tasks at the appropriate
    2156             :  * moment.
    2157             :  *
    2158             :  * This is implemented using struct set_affinity_pending. The first
    2159             :  * __set_cpus_allowed_ptr() caller within a given Migrate-Disable region will
    2160             :  * setup an instance of that struct and install it on the targeted task_struct.
    2161             :  * Any and all further callers will reuse that instance. Those then wait for
    2162             :  * a completion signaled at the tail of the CPU stopper callback (1), triggered
    2163             :  * on the end of the Migrate-Disable region (i.e. outermost migrate_enable()).
    2164             :  *
    2165             :  *
    2166             :  * (1) In the cases covered above. There is one more where the completion is
    2167             :  * signaled within affine_move_task() itself: when a subsequent affinity request
    2168             :  * cancels the need for an active migration. Consider:
    2169             :  *
    2170             :  *     Initial conditions: P0->cpus_mask = [0, 1]
    2171             :  *
    2172             :  *     P0@CPU0            P1                             P2
    2173             :  *
    2174             :  *     migrate_disable();
    2175             :  *     <preempted>
    2176             :  *                        set_cpus_allowed_ptr(P0, [1]);
    2177             :  *                          <blocks>
    2178             :  *                                                       set_cpus_allowed_ptr(P0, [0, 1]);
    2179             :  *                                                         <signal completion>
    2180             :  *                          <awakes>
    2181             :  *
    2182             :  * Note that the above is safe vs a concurrent migrate_enable(), as any
    2183             :  * pending affinity completion is preceded by an uninstallation of
    2184             :  * p->migration_pending done with p->pi_lock held.
    2185             :  */
    2186          11 : static int affine_move_task(struct rq *rq, struct task_struct *p, struct rq_flags *rf,
    2187             :                             int dest_cpu, unsigned int flags)
    2188             : {
    2189          11 :         struct set_affinity_pending my_pending = { }, *pending = NULL;
    2190          11 :         bool stop_pending, complete = false;
    2191             : 
    2192             :         /* Can the task run on the task's current CPU? If so, we're done */
    2193          11 :         if (cpumask_test_cpu(task_cpu(p), &p->cpus_mask)) {
    2194           5 :                 struct task_struct *push_task = NULL;
    2195             : 
    2196           5 :                 if ((flags & SCA_MIGRATE_ENABLE) &&
    2197           0 :                     (p->migration_flags & MDF_PUSH) && !rq->push_busy) {
    2198           0 :                         rq->push_busy = true;
    2199           0 :                         push_task = get_task_struct(p);
    2200             :                 }
    2201             : 
    2202             :                 /*
    2203             :                  * If there are pending waiters, but no pending stop_work,
    2204             :                  * then complete now.
    2205             :                  */
    2206           5 :                 pending = p->migration_pending;
    2207           5 :                 if (pending && !pending->stop_pending) {
    2208           0 :                         p->migration_pending = NULL;
    2209           0 :                         complete = true;
    2210             :                 }
    2211             : 
    2212           5 :                 task_rq_unlock(rq, p, rf);
    2213             : 
    2214           5 :                 if (push_task) {
    2215           0 :                         stop_one_cpu_nowait(rq->cpu, push_cpu_stop,
    2216             :                                             p, &rq->push_work);
    2217             :                 }
    2218             : 
    2219           5 :                 if (complete)
    2220           0 :                         complete_all(&pending->done);
    2221             : 
    2222           5 :                 return 0;
    2223             :         }
    2224             : 
    2225           6 :         if (!(flags & SCA_MIGRATE_ENABLE)) {
    2226             :                 /* serialized by p->pi_lock */
    2227           6 :                 if (!p->migration_pending) {
    2228             :                         /* Install the request */
    2229           6 :                         refcount_set(&my_pending.refs, 1);
    2230           6 :                         init_completion(&my_pending.done);
    2231           6 :                         my_pending.arg = (struct migration_arg) {
    2232             :                                 .task = p,
    2233             :                                 .dest_cpu = -1,         /* any */
    2234             :                                 .pending = &my_pending,
    2235             :                         };
    2236             : 
    2237           6 :                         p->migration_pending = &my_pending;
    2238             :                 } else {
    2239           0 :                         pending = p->migration_pending;
    2240           0 :                         refcount_inc(&pending->refs);
    2241             :                 }
    2242             :         }
    2243           6 :         pending = p->migration_pending;
    2244             :         /*
    2245             :          * - !MIGRATE_ENABLE:
    2246             :          *   we'll have installed a pending if there wasn't one already.
    2247             :          *
    2248             :          * - MIGRATE_ENABLE:
    2249             :          *   we're here because the current CPU isn't matching anymore,
    2250             :          *   the only way that can happen is because of a concurrent
    2251             :          *   set_cpus_allowed_ptr() call, which should then still be
    2252             :          *   pending completion.
    2253             :          *
    2254             :          * Either way, we really should have a @pending here.
    2255             :          */
    2256           6 :         if (WARN_ON_ONCE(!pending)) {
    2257           0 :                 task_rq_unlock(rq, p, rf);
    2258           0 :                 return -EINVAL;
    2259             :         }
    2260             : 
    2261           6 :         if (task_running(rq, p) || p->state == TASK_WAKING) {
    2262             :                 /*
    2263             :                  * MIGRATE_ENABLE gets here because 'p == current', but for
    2264             :                  * anything else we cannot do is_migration_disabled(), punt
    2265             :                  * and have the stopper function handle it all race-free.
    2266             :                  */
    2267           0 :                 stop_pending = pending->stop_pending;
    2268           0 :                 if (!stop_pending)
    2269           0 :                         pending->stop_pending = true;
    2270             : 
    2271           0 :                 if (flags & SCA_MIGRATE_ENABLE)
    2272           0 :                         p->migration_flags &= ~MDF_PUSH;
    2273             : 
    2274           0 :                 task_rq_unlock(rq, p, rf);
    2275             : 
    2276           0 :                 if (!stop_pending) {
    2277           0 :                         stop_one_cpu_nowait(cpu_of(rq), migration_cpu_stop,
    2278           0 :                                             &pending->arg, &pending->stop_work);
    2279             :                 }
    2280             : 
    2281           0 :                 if (flags & SCA_MIGRATE_ENABLE)
    2282             :                         return 0;
    2283             :         } else {
    2284             : 
    2285           6 :                 if (!is_migration_disabled(p)) {
    2286           6 :                         if (task_on_rq_queued(p))
    2287           0 :                                 rq = move_queued_task(rq, rf, p, dest_cpu);
    2288             : 
    2289           6 :                         if (!pending->stop_pending) {
    2290           6 :                                 p->migration_pending = NULL;
    2291           6 :                                 complete = true;
    2292             :                         }
    2293             :                 }
    2294           6 :                 task_rq_unlock(rq, p, rf);
    2295             : 
    2296           6 :                 if (complete)
    2297           6 :                         complete_all(&pending->done);
    2298             :         }
    2299             : 
    2300           6 :         wait_for_completion(&pending->done);
    2301             : 
    2302           6 :         if (refcount_dec_and_test(&pending->refs))
    2303           6 :                 wake_up_var(&pending->refs); /* No UaF, just an address */
    2304             : 
    2305             :         /*
    2306             :          * Block the original owner of &pending until all subsequent callers
    2307             :          * have seen the completion and decremented the refcount
    2308             :          */
    2309           6 :         wait_var_event(&my_pending.refs, !refcount_read(&my_pending.refs));
    2310             : 
    2311             :         /* ARGH */
    2312           6 :         WARN_ON_ONCE(my_pending.stop_pending);
    2313             : 
    2314             :         return 0;
    2315             : }
    2316             : 
    2317             : /*
    2318             :  * Change a given task's CPU affinity. Migrate the thread to a
    2319             :  * proper CPU and schedule it away if the CPU it's executing on
    2320             :  * is removed from the allowed bitmask.
    2321             :  *
    2322             :  * NOTE: the caller must have a valid reference to the task, the
    2323             :  * task must not exit() & deallocate itself prematurely. The
    2324             :  * call is not atomic; no spinlocks may be held.
    2325             :  */
    2326          62 : static int __set_cpus_allowed_ptr(struct task_struct *p,
    2327             :                                   const struct cpumask *new_mask,
    2328             :                                   u32 flags)
    2329             : {
    2330          62 :         const struct cpumask *cpu_valid_mask = cpu_active_mask;
    2331          62 :         unsigned int dest_cpu;
    2332          62 :         struct rq_flags rf;
    2333          62 :         struct rq *rq;
    2334          62 :         int ret = 0;
    2335             : 
    2336          62 :         rq = task_rq_lock(p, &rf);
    2337          62 :         update_rq_clock(rq);
    2338             : 
    2339          62 :         if (p->flags & PF_KTHREAD || is_migration_disabled(p)) {
    2340             :                 /*
    2341             :                  * Kernel threads are allowed on online && !active CPUs,
    2342             :                  * however, during cpu-hot-unplug, even these might get pushed
    2343             :                  * away if not KTHREAD_IS_PER_CPU.
    2344             :                  *
    2345             :                  * Specifically, migration_disabled() tasks must not fail the
    2346             :                  * cpumask_any_and_distribute() pick below, esp. so on
    2347             :                  * SCA_MIGRATE_ENABLE, otherwise we'll not call
    2348             :                  * set_cpus_allowed_common() and actually reset p->cpus_ptr.
    2349             :                  */
    2350             :                 cpu_valid_mask = cpu_online_mask;
    2351             :         }
    2352             : 
    2353             :         /*
    2354             :          * Must re-check here, to close a race against __kthread_bind(),
    2355             :          * sched_setaffinity() is not guaranteed to observe the flag.
    2356             :          */
    2357          62 :         if ((flags & SCA_CHECK) && (p->flags & PF_NO_SETAFFINITY)) {
    2358           0 :                 ret = -EINVAL;
    2359           0 :                 goto out;
    2360             :         }
    2361             : 
    2362          62 :         if (!(flags & SCA_MIGRATE_ENABLE)) {
    2363          62 :                 if (cpumask_equal(&p->cpus_mask, new_mask))
    2364          51 :                         goto out;
    2365             : 
    2366          11 :                 if (WARN_ON_ONCE(p == current &&
    2367             :                                  is_migration_disabled(p) &&
    2368             :                                  !cpumask_test_cpu(task_cpu(p), new_mask))) {
    2369           0 :                         ret = -EBUSY;
    2370           0 :                         goto out;
    2371             :                 }
    2372             :         }
    2373             : 
    2374             :         /*
    2375             :          * Picking a ~random cpu helps in cases where we are changing affinity
    2376             :          * for groups of tasks (ie. cpuset), so that load balancing is not
    2377             :          * immediately required to distribute the tasks within their new mask.
    2378             :          */
    2379          11 :         dest_cpu = cpumask_any_and_distribute(cpu_valid_mask, new_mask);
    2380          11 :         if (dest_cpu >= nr_cpu_ids) {
    2381           0 :                 ret = -EINVAL;
    2382           0 :                 goto out;
    2383             :         }
    2384             : 
    2385          11 :         __do_set_cpus_allowed(p, new_mask, flags);
    2386             : 
    2387          11 :         return affine_move_task(rq, p, &rf, dest_cpu, flags);
    2388             : 
    2389          51 : out:
    2390          51 :         task_rq_unlock(rq, p, &rf);
    2391             : 
    2392          51 :         return ret;
    2393             : }
    2394             : 
    2395          62 : int set_cpus_allowed_ptr(struct task_struct *p, const struct cpumask *new_mask)
    2396             : {
    2397          62 :         return __set_cpus_allowed_ptr(p, new_mask, 0);
    2398             : }
    2399             : EXPORT_SYMBOL_GPL(set_cpus_allowed_ptr);
    2400             : 
    2401         994 : void set_task_cpu(struct task_struct *p, unsigned int new_cpu)
    2402             : {
    2403             : #ifdef CONFIG_SCHED_DEBUG
    2404             :         /*
    2405             :          * We should never call set_task_cpu() on a blocked task,
    2406             :          * ttwu() will sort out the placement.
    2407             :          */
    2408             :         WARN_ON_ONCE(p->state != TASK_RUNNING && p->state != TASK_WAKING &&
    2409             :                         !p->on_rq);
    2410             : 
    2411             :         /*
    2412             :          * Migrating fair class task must have p->on_rq = TASK_ON_RQ_MIGRATING,
    2413             :          * because schedstat_wait_{start,end} rebase migrating task's wait_start
    2414             :          * time relying on p->on_rq.
    2415             :          */
    2416             :         WARN_ON_ONCE(p->state == TASK_RUNNING &&
    2417             :                      p->sched_class == &fair_sched_class &&
    2418             :                      (p->on_rq && !task_on_rq_migrating(p)));
    2419             : 
    2420             : #ifdef CONFIG_LOCKDEP
    2421             :         /*
    2422             :          * The caller should hold either p->pi_lock or rq->lock, when changing
    2423             :          * a task's CPU. ->pi_lock for waking tasks, rq->lock for runnable tasks.
    2424             :          *
    2425             :          * sched_move_task() holds both and thus holding either pins the cgroup,
    2426             :          * see task_group().
    2427             :          *
    2428             :          * Furthermore, all task_rq users should acquire both locks, see
    2429             :          * task_rq_lock().
    2430             :          */
    2431             :         WARN_ON_ONCE(debug_locks && !(lockdep_is_held(&p->pi_lock) ||
    2432             :                                       lockdep_is_held(&task_rq(p)->lock)));
    2433             : #endif
    2434             :         /*
    2435             :          * Clearly, migrating tasks to offline CPUs is a fairly daft thing.
    2436             :          */
    2437             :         WARN_ON_ONCE(!cpu_online(new_cpu));
    2438             : 
    2439             :         WARN_ON_ONCE(is_migration_disabled(p));
    2440             : #endif
    2441             : 
    2442         994 :         trace_sched_migrate_task(p, new_cpu);
    2443             : 
    2444         995 :         if (task_cpu(p) != new_cpu) {
    2445         995 :                 if (p->sched_class->migrate_task_rq)
    2446         992 :                         p->sched_class->migrate_task_rq(p, new_cpu);
    2447         995 :                 p->se.nr_migrations++;
    2448         995 :                 rseq_migrate(p);
    2449         995 :                 perf_event_task_migrate(p);
    2450             :         }
    2451             : 
    2452         995 :         __set_task_cpu(p, new_cpu);
    2453         995 : }
    2454             : 
    2455             : #ifdef CONFIG_NUMA_BALANCING
    2456             : static void __migrate_swap_task(struct task_struct *p, int cpu)
    2457             : {
    2458             :         if (task_on_rq_queued(p)) {
    2459             :                 struct rq *src_rq, *dst_rq;
    2460             :                 struct rq_flags srf, drf;
    2461             : 
    2462             :                 src_rq = task_rq(p);
    2463             :                 dst_rq = cpu_rq(cpu);
    2464             : 
    2465             :                 rq_pin_lock(src_rq, &srf);
    2466             :                 rq_pin_lock(dst_rq, &drf);
    2467             : 
    2468             :                 deactivate_task(src_rq, p, 0);
    2469             :                 set_task_cpu(p, cpu);
    2470             :                 activate_task(dst_rq, p, 0);
    2471             :                 check_preempt_curr(dst_rq, p, 0);
    2472             : 
    2473             :                 rq_unpin_lock(dst_rq, &drf);
    2474             :                 rq_unpin_lock(src_rq, &srf);
    2475             : 
    2476             :         } else {
    2477             :                 /*
    2478             :                  * Task isn't running anymore; make it appear like we migrated
    2479             :                  * it before it went to sleep. This means on wakeup we make the
    2480             :                  * previous CPU our target instead of where it really is.
    2481             :                  */
    2482             :                 p->wake_cpu = cpu;
    2483             :         }
    2484             : }
    2485             : 
    2486             : struct migration_swap_arg {
    2487             :         struct task_struct *src_task, *dst_task;
    2488             :         int src_cpu, dst_cpu;
    2489             : };
    2490             : 
    2491             : static int migrate_swap_stop(void *data)
    2492             : {
    2493             :         struct migration_swap_arg *arg = data;
    2494             :         struct rq *src_rq, *dst_rq;
    2495             :         int ret = -EAGAIN;
    2496             : 
    2497             :         if (!cpu_active(arg->src_cpu) || !cpu_active(arg->dst_cpu))
    2498             :                 return -EAGAIN;
    2499             : 
    2500             :         src_rq = cpu_rq(arg->src_cpu);
    2501             :         dst_rq = cpu_rq(arg->dst_cpu);
    2502             : 
    2503             :         double_raw_lock(&arg->src_task->pi_lock,
    2504             :                         &arg->dst_task->pi_lock);
    2505             :         double_rq_lock(src_rq, dst_rq);
    2506             : 
    2507             :         if (task_cpu(arg->dst_task) != arg->dst_cpu)
    2508             :                 goto unlock;
    2509             : 
    2510             :         if (task_cpu(arg->src_task) != arg->src_cpu)
    2511             :                 goto unlock;
    2512             : 
    2513             :         if (!cpumask_test_cpu(arg->dst_cpu, arg->src_task->cpus_ptr))
    2514             :                 goto unlock;
    2515             : 
    2516             :         if (!cpumask_test_cpu(arg->src_cpu, arg->dst_task->cpus_ptr))
    2517             :                 goto unlock;
    2518             : 
    2519             :         __migrate_swap_task(arg->src_task, arg->dst_cpu);
    2520             :         __migrate_swap_task(arg->dst_task, arg->src_cpu);
    2521             : 
    2522             :         ret = 0;
    2523             : 
    2524             : unlock:
    2525             :         double_rq_unlock(src_rq, dst_rq);
    2526             :         raw_spin_unlock(&arg->dst_task->pi_lock);
    2527             :         raw_spin_unlock(&arg->src_task->pi_lock);
    2528             : 
    2529             :         return ret;
    2530             : }
    2531             : 
    2532             : /*
    2533             :  * Cross migrate two tasks
    2534             :  */
    2535             : int migrate_swap(struct task_struct *cur, struct task_struct *p,
    2536             :                 int target_cpu, int curr_cpu)
    2537             : {
    2538             :         struct migration_swap_arg arg;
    2539             :         int ret = -EINVAL;
    2540             : 
    2541             :         arg = (struct migration_swap_arg){
    2542             :                 .src_task = cur,
    2543             :                 .src_cpu = curr_cpu,
    2544             :                 .dst_task = p,
    2545             :                 .dst_cpu = target_cpu,
    2546             :         };
    2547             : 
    2548             :         if (arg.src_cpu == arg.dst_cpu)
    2549             :                 goto out;
    2550             : 
    2551             :         /*
    2552             :          * These three tests are all lockless; this is OK since all of them
    2553             :          * will be re-checked with proper locks held further down the line.
    2554             :          */
    2555             :         if (!cpu_active(arg.src_cpu) || !cpu_active(arg.dst_cpu))
    2556             :                 goto out;
    2557             : 
    2558             :         if (!cpumask_test_cpu(arg.dst_cpu, arg.src_task->cpus_ptr))
    2559             :                 goto out;
    2560             : 
    2561             :         if (!cpumask_test_cpu(arg.src_cpu, arg.dst_task->cpus_ptr))
    2562             :                 goto out;
    2563             : 
    2564             :         trace_sched_swap_numa(cur, arg.src_cpu, p, arg.dst_cpu);
    2565             :         ret = stop_two_cpus(arg.dst_cpu, arg.src_cpu, migrate_swap_stop, &arg);
    2566             : 
    2567             : out:
    2568             :         return ret;
    2569             : }
    2570             : #endif /* CONFIG_NUMA_BALANCING */
    2571             : 
    2572             : /*
    2573             :  * wait_task_inactive - wait for a thread to unschedule.
    2574             :  *
    2575             :  * If @match_state is nonzero, it's the @p->state value just checked and
    2576             :  * not expected to change.  If it changes, i.e. @p might have woken up,
    2577             :  * then return zero.  When we succeed in waiting for @p to be off its CPU,
    2578             :  * we return a positive number (its total switch count).  If a second call
    2579             :  * a short while later returns the same number, the caller can be sure that
    2580             :  * @p has remained unscheduled the whole time.
    2581             :  *
    2582             :  * The caller must ensure that the task *will* unschedule sometime soon,
    2583             :  * else this function might spin for a *long* time. This function can't
    2584             :  * be called with interrupts off, or it may introduce deadlock with
    2585             :  * smp_call_function() if an IPI is sent by the same process we are
    2586             :  * waiting to become inactive.
    2587             :  */
    2588          84 : unsigned long wait_task_inactive(struct task_struct *p, long match_state)
    2589             : {
    2590          84 :         int running, queued;
    2591          84 :         struct rq_flags rf;
    2592          84 :         unsigned long ncsw;
    2593          84 :         struct rq *rq;
    2594             : 
    2595          84 :         for (;;) {
    2596             :                 /*
    2597             :                  * We do the initial early heuristics without holding
    2598             :                  * any task-queue locks at all. We'll only try to get
    2599             :                  * the runqueue lock when things look like they will
    2600             :                  * work out!
    2601             :                  */
    2602          84 :                 rq = task_rq(p);
    2603             : 
    2604             :                 /*
    2605             :                  * If the task is actively running on another CPU
    2606             :                  * still, just relax and busy-wait without holding
    2607             :                  * any locks.
    2608             :                  *
    2609             :                  * NOTE! Since we don't hold any locks, it's not
    2610             :                  * even sure that "rq" stays as the right runqueue!
    2611             :                  * But we don't care, since "task_running()" will
    2612             :                  * return false if the runqueue has changed and p
    2613             :                  * is actually now running somewhere else!
    2614             :                  */
    2615          84 :                 while (task_running(rq, p)) {
    2616           0 :                         if (match_state && unlikely(p->state != match_state))
    2617             :                                 return 0;
    2618           0 :                         cpu_relax();
    2619             :                 }
    2620             : 
    2621             :                 /*
    2622             :                  * Ok, time to look more closely! We need the rq
    2623             :                  * lock now, to be *sure*. If we're wrong, we'll
    2624             :                  * just go back and repeat.
    2625             :                  */
    2626          84 :                 rq = task_rq_lock(p, &rf);
    2627          84 :                 trace_sched_wait_task(p);
    2628          84 :                 running = task_running(rq, p);
    2629          84 :                 queued = task_on_rq_queued(p);
    2630          84 :                 ncsw = 0;
    2631          84 :                 if (!match_state || p->state == match_state)
    2632          84 :                         ncsw = p->nvcsw | LONG_MIN; /* sets MSB */
    2633          84 :                 task_rq_unlock(rq, p, &rf);
    2634             : 
    2635             :                 /*
    2636             :                  * If it changed from the expected state, bail out now.
    2637             :                  */
    2638          84 :                 if (unlikely(!ncsw))
    2639             :                         break;
    2640             : 
    2641             :                 /*
    2642             :                  * Was it really running after all now that we
    2643             :                  * checked with the proper locks actually held?
    2644             :                  *
    2645             :                  * Oops. Go back and try again..
    2646             :                  */
    2647          84 :                 if (unlikely(running)) {
    2648           0 :                         cpu_relax();
    2649           0 :                         continue;
    2650             :                 }
    2651             : 
    2652             :                 /*
    2653             :                  * It's not enough that it's not actively running,
    2654             :                  * it must be off the runqueue _entirely_, and not
    2655             :                  * preempted!
    2656             :                  *
    2657             :                  * So if it was still runnable (but just not actively
    2658             :                  * running right now), it's preempted, and we should
    2659             :                  * yield - it could be a while.
    2660             :                  */
    2661          84 :                 if (unlikely(queued)) {
    2662           0 :                         ktime_t to = NSEC_PER_SEC / HZ;
    2663             : 
    2664           0 :                         set_current_state(TASK_UNINTERRUPTIBLE);
    2665           0 :                         schedule_hrtimeout(&to, HRTIMER_MODE_REL);
    2666           0 :                         continue;
    2667             :                 }
    2668             : 
    2669             :                 /*
    2670             :                  * Ahh, all good. It wasn't running, and it wasn't
    2671             :                  * runnable, which means that it will never become
    2672             :                  * running in the future either. We're all done!
    2673             :                  */
    2674             :                 break;
    2675             :         }
    2676             : 
    2677             :         return ncsw;
    2678             : }
    2679             : 
    2680             : /***
    2681             :  * kick_process - kick a running thread to enter/exit the kernel
    2682             :  * @p: the to-be-kicked thread
    2683             :  *
    2684             :  * Cause a process which is running on another CPU to enter
    2685             :  * kernel-mode, without any delay. (to get signals handled.)
    2686             :  *
    2687             :  * NOTE: this function doesn't have to take the runqueue lock,
    2688             :  * because all it wants to ensure is that the remote task enters
    2689             :  * the kernel. If the IPI races and the task has been migrated
    2690             :  * to another CPU then no harm is done and the purpose has been
    2691             :  * achieved as well.
    2692             :  */
    2693       51704 : void kick_process(struct task_struct *p)
    2694             : {
    2695       51704 :         int cpu;
    2696             : 
    2697       51704 :         preempt_disable();
    2698       51713 :         cpu = task_cpu(p);
    2699       51713 :         if ((cpu != smp_processor_id()) && task_curr(p))
    2700          40 :                 smp_send_reschedule(cpu);
    2701       51713 :         preempt_enable();
    2702       51712 : }
    2703             : EXPORT_SYMBOL_GPL(kick_process);
    2704             : 
    2705             : /*
    2706             :  * ->cpus_ptr is protected by both rq->lock and p->pi_lock
    2707             :  *
    2708             :  * A few notes on cpu_active vs cpu_online:
    2709             :  *
    2710             :  *  - cpu_active must be a subset of cpu_online
    2711             :  *
    2712             :  *  - on CPU-up we allow per-CPU kthreads on the online && !active CPU,
    2713             :  *    see __set_cpus_allowed_ptr(). At this point the newly online
    2714             :  *    CPU isn't yet part of the sched domains, and balancing will not
    2715             :  *    see it.
    2716             :  *
    2717             :  *  - on CPU-down we clear cpu_active() to mask the sched domains and
    2718             :  *    avoid the load balancer to place new tasks on the to be removed
    2719             :  *    CPU. Existing tasks will remain running there and will be taken
    2720             :  *    off.
    2721             :  *
    2722             :  * This means that fallback selection must not select !active CPUs.
    2723             :  * And can assume that any active CPU must be online. Conversely
    2724             :  * select_task_rq() below may allow selection of !active CPUs in order
    2725             :  * to satisfy the above rules.
    2726             :  */
    2727          15 : static int select_fallback_rq(int cpu, struct task_struct *p)
    2728             : {
    2729          15 :         int nid = cpu_to_node(cpu);
    2730          15 :         const struct cpumask *nodemask = NULL;
    2731          15 :         enum { cpuset, possible, fail } state = cpuset;
    2732          15 :         int dest_cpu;
    2733             : 
    2734             :         /*
    2735             :          * If the node that the CPU is on has been offlined, cpu_to_node()
    2736             :          * will return -1. There is no CPU on the node, and we should
    2737             :          * select the CPU on the other node.
    2738             :          */
    2739          15 :         if (nid != -1) {
    2740          15 :                 nodemask = cpumask_of_node(nid);
    2741             : 
    2742             :                 /* Look for allowed, online CPU in same node. */
    2743          45 :                 for_each_cpu(dest_cpu, nodemask) {
    2744          30 :                         if (!cpu_active(dest_cpu))
    2745           0 :                                 continue;
    2746          30 :                         if (cpumask_test_cpu(dest_cpu, p->cpus_ptr))
    2747           0 :                                 return dest_cpu;
    2748             :                 }
    2749             :         }
    2750             : 
    2751          30 :         for (;;) {
    2752             :                 /* Any allowed, online CPU? */
    2753          45 :                 for_each_cpu(dest_cpu, p->cpus_ptr) {
    2754          30 :                         if (!is_cpu_allowed(p, dest_cpu))
    2755          15 :                                 continue;
    2756             : 
    2757          15 :                         goto out;
    2758             :                 }
    2759             : 
    2760             :                 /* No more Mr. Nice Guy. */
    2761          15 :                 switch (state) {
    2762             :                 case cpuset:
    2763             :                         if (IS_ENABLED(CONFIG_CPUSETS)) {
    2764             :                                 cpuset_cpus_allowed_fallback(p);
    2765             :                                 state = possible;
    2766             :                                 break;
    2767             :                         }
    2768          15 :                         fallthrough;
    2769             :                 case possible:
    2770             :                         /*
    2771             :                          * XXX When called from select_task_rq() we only
    2772             :                          * hold p->pi_lock and again violate locking order.
    2773             :                          *
    2774             :                          * More yuck to audit.
    2775             :                          */
    2776          15 :                         do_set_cpus_allowed(p, cpu_possible_mask);
    2777          15 :                         state = fail;
    2778          15 :                         break;
    2779             : 
    2780           0 :                 case fail:
    2781           0 :                         BUG();
    2782             :                         break;
    2783             :                 }
    2784             :         }
    2785             : 
    2786          15 : out:
    2787          15 :         if (state != cpuset) {
    2788             :                 /*
    2789             :                  * Don't tell them about moving exiting tasks or
    2790             :                  * kernel threads (both mm NULL), since they never
    2791             :                  * leave kernel.
    2792             :                  */
    2793          15 :                 if (p->mm && printk_ratelimit()) {
    2794           0 :                         printk_deferred("process %d (%s) no longer affine to cpu%d\n",
    2795           0 :                                         task_pid_nr(p), p->comm, cpu);
    2796             :                 }
    2797             :         }
    2798             : 
    2799             :         return dest_cpu;
    2800             : }
    2801             : 
    2802             : /*
    2803             :  * The caller (fork, wakeup) owns p->pi_lock, ->cpus_ptr is stable.
    2804             :  */
    2805             : static inline
    2806       14785 : int select_task_rq(struct task_struct *p, int cpu, int wake_flags)
    2807             : {
    2808       29576 :         lockdep_assert_held(&p->pi_lock);
    2809             : 
    2810       14789 :         if (p->nr_cpus_allowed > 1 && !is_migration_disabled(p))
    2811       11048 :                 cpu = p->sched_class->select_task_rq(p, cpu, wake_flags);
    2812             :         else
    2813        3741 :                 cpu = cpumask_any(p->cpus_ptr);
    2814             : 
    2815             :         /*
    2816             :          * In order not to call set_task_cpu() on a blocking task we need
    2817             :          * to rely on ttwu() to place the task on a valid ->cpus_ptr
    2818             :          * CPU.
    2819             :          *
    2820             :          * Since this is common to all placement strategies, this lives here.
    2821             :          *
    2822             :          * [ this allows ->select_task() to simply return task_cpu(p) and
    2823             :          *   not worry about this generic constraint ]
    2824             :          */
    2825       14791 :         if (unlikely(!is_cpu_allowed(p, cpu)))
    2826          15 :                 cpu = select_fallback_rq(task_cpu(p), p);
    2827             : 
    2828       14789 :         return cpu;
    2829             : }
    2830             : 
    2831           4 : void sched_set_stop_task(int cpu, struct task_struct *stop)
    2832             : {
    2833           4 :         static struct lock_class_key stop_pi_lock;
    2834           4 :         struct sched_param param = { .sched_priority = MAX_RT_PRIO - 1 };
    2835           4 :         struct task_struct *old_stop = cpu_rq(cpu)->stop;
    2836             : 
    2837           4 :         if (stop) {
    2838             :                 /*
    2839             :                  * Make it appear like a SCHED_FIFO task, its something
    2840             :                  * userspace knows about and won't get confused about.
    2841             :                  *
    2842             :                  * Also, it will make PI more or less work without too
    2843             :                  * much confusion -- but then, stop work should not
    2844             :                  * rely on PI working anyway.
    2845             :                  */
    2846           8 :                 sched_setscheduler_nocheck(stop, SCHED_FIFO, &param);
    2847             : 
    2848           4 :                 stop->sched_class = &stop_sched_class;
    2849             : 
    2850             :                 /*
    2851             :                  * The PI code calls rt_mutex_setprio() with ->pi_lock held to
    2852             :                  * adjust the effective priority of a task. As a result,
    2853             :                  * rt_mutex_setprio() can trigger (RT) balancing operations,
    2854             :                  * which can then trigger wakeups of the stop thread to push
    2855             :                  * around the current task.
    2856             :                  *
    2857             :                  * The stop task itself will never be part of the PI-chain, it
    2858             :                  * never blocks, therefore that ->pi_lock recursion is safe.
    2859             :                  * Tell lockdep about this by placing the stop->pi_lock in its
    2860             :                  * own class.
    2861             :                  */
    2862           4 :                 lockdep_set_class(&stop->pi_lock, &stop_pi_lock);
    2863             :         }
    2864             : 
    2865           4 :         cpu_rq(cpu)->stop = stop;
    2866             : 
    2867           4 :         if (old_stop) {
    2868             :                 /*
    2869             :                  * Reset it back to a normal scheduling class so that
    2870             :                  * it can die in pieces.
    2871             :                  */
    2872           0 :                 old_stop->sched_class = &rt_sched_class;
    2873             :         }
    2874           4 : }
    2875             : 
    2876             : #else /* CONFIG_SMP */
    2877             : 
    2878             : static inline int __set_cpus_allowed_ptr(struct task_struct *p,
    2879             :                                          const struct cpumask *new_mask,
    2880             :                                          u32 flags)
    2881             : {
    2882             :         return set_cpus_allowed_ptr(p, new_mask);
    2883             : }
    2884             : 
    2885             : static inline void migrate_disable_switch(struct rq *rq, struct task_struct *p) { }
    2886             : 
    2887             : static inline bool rq_has_pinned_tasks(struct rq *rq)
    2888             : {
    2889             :         return false;
    2890             : }
    2891             : 
    2892             : #endif /* !CONFIG_SMP */
    2893             : 
    2894             : static void
    2895       14026 : ttwu_stat(struct task_struct *p, int cpu, int wake_flags)
    2896             : {
    2897             :         struct rq *rq;
    2898             : 
    2899             :         if (!schedstat_enabled())
    2900             :                 return;
    2901             : 
    2902             :         rq = this_rq();
    2903             : 
    2904             : #ifdef CONFIG_SMP
    2905             :         if (cpu == rq->cpu) {
    2906             :                 __schedstat_inc(rq->ttwu_local);
    2907             :                 __schedstat_inc(p->se.statistics.nr_wakeups_local);
    2908             :         } else {
    2909             :                 struct sched_domain *sd;
    2910             : 
    2911             :                 __schedstat_inc(p->se.statistics.nr_wakeups_remote);
    2912             :                 rcu_read_lock();
    2913             :                 for_each_domain(rq->cpu, sd) {
    2914             :                         if (cpumask_test_cpu(cpu, sched_domain_span(sd))) {
    2915             :                                 __schedstat_inc(sd->ttwu_wake_remote);
    2916             :                                 break;
    2917             :                         }
    2918             :                 }
    2919             :                 rcu_read_unlock();
    2920             :         }
    2921             : 
    2922             :         if (wake_flags & WF_MIGRATED)
    2923             :                 __schedstat_inc(p->se.statistics.nr_wakeups_migrate);
    2924             : #endif /* CONFIG_SMP */
    2925             : 
    2926             :         __schedstat_inc(rq->ttwu_count);
    2927             :         __schedstat_inc(p->se.statistics.nr_wakeups);
    2928             : 
    2929             :         if (wake_flags & WF_SYNC)
    2930             :                 __schedstat_inc(p->se.statistics.nr_wakeups_sync);
    2931             : }
    2932             : 
    2933             : /*
    2934             :  * Mark the task runnable and perform wakeup-preemption.
    2935             :  */
    2936       14023 : static void ttwu_do_wakeup(struct rq *rq, struct task_struct *p, int wake_flags,
    2937             :                            struct rq_flags *rf)
    2938             : {
    2939       14023 :         check_preempt_curr(rq, p, wake_flags);
    2940       14022 :         p->state = TASK_RUNNING;
    2941       14022 :         trace_sched_wakeup(p);
    2942             : 
    2943             : #ifdef CONFIG_SMP
    2944       14017 :         if (p->sched_class->task_woken) {
    2945             :                 /*
    2946             :                  * Our task @p is fully woken up and running; so it's safe to
    2947             :                  * drop the rq->lock, hereafter rq is only used for statistics.
    2948             :                  */
    2949           0 :                 rq_unpin_lock(rq, rf);
    2950           0 :                 p->sched_class->task_woken(rq, p);
    2951           0 :                 rq_repin_lock(rq, rf);
    2952             :         }
    2953             : 
    2954       14017 :         if (rq->idle_stamp) {
    2955        6461 :                 u64 delta = rq_clock(rq) - rq->idle_stamp;
    2956        6465 :                 u64 max = 2*rq->max_idle_balance_cost;
    2957             : 
    2958        6465 :                 update_avg(&rq->avg_idle, delta);
    2959             : 
    2960        6465 :                 if (rq->avg_idle > max)
    2961        3683 :                         rq->avg_idle = max;
    2962             : 
    2963        6465 :                 rq->idle_stamp = 0;
    2964             :         }
    2965             : #endif
    2966       14021 : }
    2967             : 
    2968             : static void
    2969       13856 : ttwu_do_activate(struct rq *rq, struct task_struct *p, int wake_flags,
    2970             :                  struct rq_flags *rf)
    2971             : {
    2972       13856 :         int en_flags = ENQUEUE_WAKEUP | ENQUEUE_NOCLOCK;
    2973             : 
    2974       27716 :         lockdep_assert_held(&rq->lock);
    2975             : 
    2976       13859 :         if (p->sched_contributes_to_load)
    2977        2713 :                 rq->nr_uninterruptible--;
    2978             : 
    2979             : #ifdef CONFIG_SMP
    2980       13859 :         if (wake_flags & WF_MIGRATED)
    2981             :                 en_flags |= ENQUEUE_MIGRATED;
    2982             :         else
    2983             : #endif
    2984       13751 :         if (p->in_iowait) {
    2985        1873 :                 delayacct_blkio_end(p);
    2986        1873 :                 atomic_dec(&task_rq(p)->nr_iowait);
    2987             :         }
    2988             : 
    2989       13859 :         activate_task(rq, p, en_flags);
    2990       13861 :         ttwu_do_wakeup(rq, p, wake_flags, rf);
    2991       13858 : }
    2992             : 
    2993             : /*
    2994             :  * Consider @p being inside a wait loop:
    2995             :  *
    2996             :  *   for (;;) {
    2997             :  *      set_current_state(TASK_UNINTERRUPTIBLE);
    2998             :  *
    2999             :  *      if (CONDITION)
    3000             :  *         break;
    3001             :  *
    3002             :  *      schedule();
    3003             :  *   }
    3004             :  *   __set_current_state(TASK_RUNNING);
    3005             :  *
    3006             :  * between set_current_state() and schedule(). In this case @p is still
    3007             :  * runnable, so all that needs doing is change p->state back to TASK_RUNNING in
    3008             :  * an atomic manner.
    3009             :  *
    3010             :  * By taking task_rq(p)->lock we serialize against schedule(), if @p->on_rq
    3011             :  * then schedule() must still happen and p->state can be changed to
    3012             :  * TASK_RUNNING. Otherwise we lost the race, schedule() has happened, and we
    3013             :  * need to do a full wakeup with enqueue.
    3014             :  *
    3015             :  * Returns: %true when the wakeup is done,
    3016             :  *          %false otherwise.
    3017             :  */
    3018         171 : static int ttwu_runnable(struct task_struct *p, int wake_flags)
    3019             : {
    3020         171 :         struct rq_flags rf;
    3021         171 :         struct rq *rq;
    3022         171 :         int ret = 0;
    3023             : 
    3024         171 :         rq = __task_rq_lock(p, &rf);
    3025         171 :         if (task_on_rq_queued(p)) {
    3026             :                 /* check_preempt_curr() may use rq clock */
    3027         162 :                 update_rq_clock(rq);
    3028         162 :                 ttwu_do_wakeup(rq, p, wake_flags, &rf);
    3029         162 :                 ret = 1;
    3030             :         }
    3031         171 :         __task_rq_unlock(rq, &rf);
    3032             : 
    3033         171 :         return ret;
    3034             : }
    3035             : 
    3036             : #ifdef CONFIG_SMP
    3037        4170 : void sched_ttwu_pending(void *arg)
    3038             : {
    3039        4170 :         struct llist_node *llist = arg;
    3040        4170 :         struct rq *rq = this_rq();
    3041        4171 :         struct task_struct *p, *t;
    3042        4171 :         struct rq_flags rf;
    3043             : 
    3044        4171 :         if (!llist)
    3045           0 :                 return;
    3046             : 
    3047             :         /*
    3048             :          * rq::ttwu_pending racy indication of out-standing wakeups.
    3049             :          * Races such that false-negatives are possible, since they
    3050             :          * are shorter lived that false-positives would be.
    3051             :          */
    3052        4171 :         WRITE_ONCE(rq->ttwu_pending, 0);
    3053             : 
    3054        4171 :         rq_lock_irqsave(rq, &rf);
    3055        4174 :         update_rq_clock(rq);
    3056             : 
    3057        8359 :         llist_for_each_entry_safe(p, t, llist, wake_entry.llist) {
    3058        4185 :                 if (WARN_ON_ONCE(p->on_cpu))
    3059           0 :                         smp_cond_load_acquire(&p->on_cpu, !VAL);
    3060             : 
    3061        4185 :                 if (WARN_ON_ONCE(task_cpu(p) != cpu_of(rq)))
    3062           0 :                         set_task_cpu(p, cpu_of(rq));
    3063             : 
    3064        4185 :                 ttwu_do_activate(rq, p, p->sched_remote_wakeup ? WF_MIGRATED : 0, &rf);
    3065             :         }
    3066             : 
    3067        4174 :         rq_unlock_irqrestore(rq, &rf);
    3068             : }
    3069             : 
    3070        7103 : void send_call_function_single_ipi(int cpu)
    3071             : {
    3072        7103 :         struct rq *rq = cpu_rq(cpu);
    3073             : 
    3074        7103 :         if (!set_nr_if_polling(rq->idle))
    3075        7075 :                 arch_send_call_function_single_ipi(cpu);
    3076             :         else
    3077          28 :                 trace_sched_wake_idle_without_ipi(cpu);
    3078        7103 : }
    3079             : 
    3080             : /*
    3081             :  * Queue a task on the target CPUs wake_list and wake the CPU via IPI if
    3082             :  * necessary. The wakee CPU on receipt of the IPI will queue the task
    3083             :  * via sched_ttwu_wakeup() for activation so the wakee incurs the cost
    3084             :  * of the wakeup instead of the waker.
    3085             :  */
    3086        4188 : static void __ttwu_queue_wakelist(struct task_struct *p, int cpu, int wake_flags)
    3087             : {
    3088        4188 :         struct rq *rq = cpu_rq(cpu);
    3089             : 
    3090        4188 :         p->sched_remote_wakeup = !!(wake_flags & WF_MIGRATED);
    3091             : 
    3092        4188 :         WRITE_ONCE(rq->ttwu_pending, 1);
    3093        4188 :         __smp_call_single_queue(cpu, &p->wake_entry.llist);
    3094        4188 : }
    3095             : 
    3096           0 : void wake_up_if_idle(int cpu)
    3097             : {
    3098           0 :         struct rq *rq = cpu_rq(cpu);
    3099           0 :         struct rq_flags rf;
    3100             : 
    3101           0 :         rcu_read_lock();
    3102             : 
    3103           0 :         if (!is_idle_task(rcu_dereference(rq->curr)))
    3104           0 :                 goto out;
    3105             : 
    3106           0 :         if (set_nr_if_polling(rq->idle)) {
    3107           0 :                 trace_sched_wake_idle_without_ipi(cpu);
    3108             :         } else {
    3109           0 :                 rq_lock_irqsave(rq, &rf);
    3110           0 :                 if (is_idle_task(rq->curr))
    3111           0 :                         smp_send_reschedule(cpu);
    3112             :                 /* Else CPU is not idle, do nothing here: */
    3113           0 :                 rq_unlock_irqrestore(rq, &rf);
    3114             :         }
    3115             : 
    3116           0 : out:
    3117           0 :         rcu_read_unlock();
    3118           0 : }
    3119             : 
    3120       20953 : bool cpus_share_cache(int this_cpu, int that_cpu)
    3121             : {
    3122       20953 :         return per_cpu(sd_llc_id, this_cpu) == per_cpu(sd_llc_id, that_cpu);
    3123             : }
    3124             : 
    3125       13854 : static inline bool ttwu_queue_cond(int cpu, int wake_flags)
    3126             : {
    3127             :         /*
    3128             :          * Do not complicate things with the async wake_list while the CPU is
    3129             :          * in hotplug state.
    3130             :          */
    3131       13854 :         if (!cpu_active(cpu))
    3132             :                 return false;
    3133             : 
    3134             :         /*
    3135             :          * If the CPU does not share cache, then queue the task on the
    3136             :          * remote rqs wakelist to avoid accessing remote data.
    3137             :          */
    3138       13844 :         if (!cpus_share_cache(smp_processor_id(), cpu))
    3139             :                 return true;
    3140             : 
    3141             :         /*
    3142             :          * If the task is descheduling and the only running task on the
    3143             :          * CPU then use the wakelist to offload the task activation to
    3144             :          * the soon-to-be-idle CPU as the current CPU is likely busy.
    3145             :          * nr_running is checked to avoid unnecessary task stacking.
    3146             :          */
    3147        9657 :         if ((wake_flags & WF_ON_CPU) && cpu_rq(cpu)->nr_running <= 1)
    3148           1 :                 return true;
    3149             : 
    3150             :         return false;
    3151             : }
    3152             : 
    3153       13855 : static bool ttwu_queue_wakelist(struct task_struct *p, int cpu, int wake_flags)
    3154             : {
    3155       13855 :         if (sched_feat(TTWU_QUEUE) && ttwu_queue_cond(cpu, wake_flags)) {
    3156        4188 :                 if (WARN_ON_ONCE(cpu == smp_processor_id()))
    3157             :                         return false;
    3158             : 
    3159        4188 :                 sched_clock_cpu(cpu); /* Sync clocks across CPUs */
    3160        4188 :                 __ttwu_queue_wakelist(p, cpu, wake_flags);
    3161        4188 :                 return true;
    3162             :         }
    3163             : 
    3164             :         return false;
    3165             : }
    3166             : 
    3167             : #else /* !CONFIG_SMP */
    3168             : 
    3169             : static inline bool ttwu_queue_wakelist(struct task_struct *p, int cpu, int wake_flags)
    3170             : {
    3171             :         return false;
    3172             : }
    3173             : 
    3174             : #endif /* CONFIG_SMP */
    3175             : 
    3176       13810 : static void ttwu_queue(struct task_struct *p, int cpu, int wake_flags)
    3177             : {
    3178       13810 :         struct rq *rq = cpu_rq(cpu);
    3179       13810 :         struct rq_flags rf;
    3180             : 
    3181       13810 :         if (ttwu_queue_wakelist(p, cpu, wake_flags))
    3182        4140 :                 return;
    3183             : 
    3184        9668 :         rq_lock(rq, &rf);
    3185        9673 :         update_rq_clock(rq);
    3186        9674 :         ttwu_do_activate(rq, p, wake_flags, &rf);
    3187       19344 :         rq_unlock(rq, &rf);
    3188             : }
    3189             : 
    3190             : /*
    3191             :  * Notes on Program-Order guarantees on SMP systems.
    3192             :  *
    3193             :  *  MIGRATION
    3194             :  *
    3195             :  * The basic program-order guarantee on SMP systems is that when a task [t]
    3196             :  * migrates, all its activity on its old CPU [c0] happens-before any subsequent
    3197             :  * execution on its new CPU [c1].
    3198             :  *
    3199             :  * For migration (of runnable tasks) this is provided by the following means:
    3200             :  *
    3201             :  *  A) UNLOCK of the rq(c0)->lock scheduling out task t
    3202             :  *  B) migration for t is required to synchronize *both* rq(c0)->lock and
    3203             :  *     rq(c1)->lock (if not at the same time, then in that order).
    3204             :  *  C) LOCK of the rq(c1)->lock scheduling in task
    3205             :  *
    3206             :  * Release/acquire chaining guarantees that B happens after A and C after B.
    3207             :  * Note: the CPU doing B need not be c0 or c1
    3208             :  *
    3209             :  * Example:
    3210             :  *
    3211             :  *   CPU0            CPU1            CPU2
    3212             :  *
    3213             :  *   LOCK rq(0)->lock
    3214             :  *   sched-out X
    3215             :  *   sched-in Y
    3216             :  *   UNLOCK rq(0)->lock
    3217             :  *
    3218             :  *                                   LOCK rq(0)->lock // orders against CPU0
    3219             :  *                                   dequeue X
    3220             :  *                                   UNLOCK rq(0)->lock
    3221             :  *
    3222             :  *                                   LOCK rq(1)->lock
    3223             :  *                                   enqueue X
    3224             :  *                                   UNLOCK rq(1)->lock
    3225             :  *
    3226             :  *                   LOCK rq(1)->lock // orders against CPU2
    3227             :  *                   sched-out Z
    3228             :  *                   sched-in X
    3229             :  *                   UNLOCK rq(1)->lock
    3230             :  *
    3231             :  *
    3232             :  *  BLOCKING -- aka. SLEEP + WAKEUP
    3233             :  *
    3234             :  * For blocking we (obviously) need to provide the same guarantee as for
    3235             :  * migration. However the means are completely different as there is no lock
    3236             :  * chain to provide order. Instead we do:
    3237             :  *
    3238             :  *   1) smp_store_release(X->on_cpu, 0)   -- finish_task()
    3239             :  *   2) smp_cond_load_acquire(!X->on_cpu) -- try_to_wake_up()
    3240             :  *
    3241             :  * Example:
    3242             :  *
    3243             :  *   CPU0 (schedule)  CPU1 (try_to_wake_up) CPU2 (schedule)
    3244             :  *
    3245             :  *   LOCK rq(0)->lock LOCK X->pi_lock
    3246             :  *   dequeue X
    3247             :  *   sched-out X
    3248             :  *   smp_store_release(X->on_cpu, 0);
    3249             :  *
    3250             :  *                    smp_cond_load_acquire(&X->on_cpu, !VAL);
    3251             :  *                    X->state = WAKING
    3252             :  *                    set_task_cpu(X,2)
    3253             :  *
    3254             :  *                    LOCK rq(2)->lock
    3255             :  *                    enqueue X
    3256             :  *                    X->state = RUNNING
    3257             :  *                    UNLOCK rq(2)->lock
    3258             :  *
    3259             :  *                                          LOCK rq(2)->lock // orders against CPU1
    3260             :  *                                          sched-out Z
    3261             :  *                                          sched-in X
    3262             :  *                                          UNLOCK rq(2)->lock
    3263             :  *
    3264             :  *                    UNLOCK X->pi_lock
    3265             :  *   UNLOCK rq(0)->lock
    3266             :  *
    3267             :  *
    3268             :  * However, for wakeups there is a second guarantee we must provide, namely we
    3269             :  * must ensure that CONDITION=1 done by the caller can not be reordered with
    3270             :  * accesses to the task state; see try_to_wake_up() and set_current_state().
    3271             :  */
    3272             : 
    3273             : /**
    3274             :  * try_to_wake_up - wake up a thread
    3275             :  * @p: the thread to be awakened
    3276             :  * @state: the mask of task states that can be woken
    3277             :  * @wake_flags: wake modifier flags (WF_*)
    3278             :  *
    3279             :  * Conceptually does:
    3280             :  *
    3281             :  *   If (@state & @p->state) @p->state = TASK_RUNNING.
    3282             :  *
    3283             :  * If the task was not queued/runnable, also place it back on a runqueue.
    3284             :  *
    3285             :  * This function is atomic against schedule() which would dequeue the task.
    3286             :  *
    3287             :  * It issues a full memory barrier before accessing @p->state, see the comment
    3288             :  * with set_current_state().
    3289             :  *
    3290             :  * Uses p->pi_lock to serialize against concurrent wake-ups.
    3291             :  *
    3292             :  * Relies on p->pi_lock stabilizing:
    3293             :  *  - p->sched_class
    3294             :  *  - p->cpus_ptr
    3295             :  *  - p->sched_task_group
    3296             :  * in order to do migration, see its use of select_task_rq()/set_task_cpu().
    3297             :  *
    3298             :  * Tries really hard to only take one task_rq(p)->lock for performance.
    3299             :  * Takes rq->lock in:
    3300             :  *  - ttwu_runnable()    -- old rq, unavoidable, see comment there;
    3301             :  *  - ttwu_queue()       -- new rq, for enqueue of the task;
    3302             :  *  - psi_ttwu_dequeue() -- much sadness :-( accounting will kill us.
    3303             :  *
    3304             :  * As a consequence we race really badly with just about everything. See the
    3305             :  * many memory barriers and their comments for details.
    3306             :  *
    3307             :  * Return: %true if @p->state changes (an actual wakeup was done),
    3308             :  *         %false otherwise.
    3309             :  */
    3310             : static int
    3311       15701 : try_to_wake_up(struct task_struct *p, unsigned int state, int wake_flags)
    3312             : {
    3313       15701 :         unsigned long flags;
    3314       15701 :         int cpu, success = 0;
    3315             : 
    3316       15701 :         preempt_disable();
    3317       15704 :         if (p == current) {
    3318             :                 /*
    3319             :                  * We're waking current, this means 'p->on_rq' and 'task_cpu(p)
    3320             :                  * == smp_processor_id()'. Together this means we can special
    3321             :                  * case the whole 'p->on_rq && ttwu_runnable()' case below
    3322             :                  * without taking any locks.
    3323             :                  *
    3324             :                  * In particular:
    3325             :                  *  - we rely on Program-Order guarantees for all the ordering,
    3326             :                  *  - we're serialized against set_special_state() by virtue of
    3327             :                  *    it disabling IRQs (this allows not taking ->pi_lock).
    3328             :                  */
    3329         153 :                 if (!(p->state & state))
    3330         150 :                         goto out;
    3331             : 
    3332           3 :                 success = 1;
    3333           3 :                 trace_sched_waking(p);
    3334           3 :                 p->state = TASK_RUNNING;
    3335           3 :                 trace_sched_wakeup(p);
    3336           3 :                 goto out;
    3337             :         }
    3338             : 
    3339             :         /*
    3340             :          * If we are going to wake up a thread waiting for CONDITION we
    3341             :          * need to ensure that CONDITION=1 done by the caller can not be
    3342             :          * reordered with p->state check below. This pairs with smp_store_mb()
    3343             :          * in set_current_state() that the waiting thread does.
    3344             :          */
    3345       15551 :         raw_spin_lock_irqsave(&p->pi_lock, flags);
    3346       15554 :         smp_mb__after_spinlock();
    3347       15554 :         if (!(p->state & state))
    3348        1531 :                 goto unlock;
    3349             : 
    3350       14023 :         trace_sched_waking(p);
    3351             : 
    3352             :         /* We're going to change ->state: */
    3353       14023 :         success = 1;
    3354             : 
    3355             :         /*
    3356             :          * Ensure we load p->on_rq _after_ p->state, otherwise it would
    3357             :          * be possible to, falsely, observe p->on_rq == 0 and get stuck
    3358             :          * in smp_cond_load_acquire() below.
    3359             :          *
    3360             :          * sched_ttwu_pending()                 try_to_wake_up()
    3361             :          *   STORE p->on_rq = 1                        LOAD p->state
    3362             :          *   UNLOCK rq->lock
    3363             :          *
    3364             :          * __schedule() (switch to task 'p')
    3365             :          *   LOCK rq->lock                     smp_rmb();
    3366             :          *   smp_mb__after_spinlock();
    3367             :          *   UNLOCK rq->lock
    3368             :          *
    3369             :          * [task p]
    3370             :          *   STORE p->state = UNINTERRUPTIBLE          LOAD p->on_rq
    3371             :          *
    3372             :          * Pairs with the LOCK+smp_mb__after_spinlock() on rq->lock in
    3373             :          * __schedule().  See the comment for smp_mb__after_spinlock().
    3374             :          *
    3375             :          * A similar smb_rmb() lives in try_invoke_on_locked_down_task().
    3376             :          */
    3377       14023 :         smp_rmb();
    3378       14024 :         if (READ_ONCE(p->on_rq) && ttwu_runnable(p, wake_flags))
    3379         162 :                 goto unlock;
    3380             : 
    3381             : #ifdef CONFIG_SMP
    3382             :         /*
    3383             :          * Ensure we load p->on_cpu _after_ p->on_rq, otherwise it would be
    3384             :          * possible to, falsely, observe p->on_cpu == 0.
    3385             :          *
    3386             :          * One must be running (->on_cpu == 1) in order to remove oneself
    3387             :          * from the runqueue.
    3388             :          *
    3389             :          * __schedule() (switch to task 'p')    try_to_wake_up()
    3390             :          *   STORE p->on_cpu = 1               LOAD p->on_rq
    3391             :          *   UNLOCK rq->lock
    3392             :          *
    3393             :          * __schedule() (put 'p' to sleep)
    3394             :          *   LOCK rq->lock                     smp_rmb();
    3395             :          *   smp_mb__after_spinlock();
    3396             :          *   STORE p->on_rq = 0                        LOAD p->on_cpu
    3397             :          *
    3398             :          * Pairs with the LOCK+smp_mb__after_spinlock() on rq->lock in
    3399             :          * __schedule().  See the comment for smp_mb__after_spinlock().
    3400             :          *
    3401             :          * Form a control-dep-acquire with p->on_rq == 0 above, to ensure
    3402             :          * schedule()'s deactivate_task() has 'happened' and p will no longer
    3403             :          * care about it's own p->state. See the comment in __schedule().
    3404             :          */
    3405       13862 :         smp_acquire__after_ctrl_dep();
    3406             : 
    3407             :         /*
    3408             :          * We're doing the wakeup (@success == 1), they did a dequeue (p->on_rq
    3409             :          * == 0), which means we need to do an enqueue, change p->state to
    3410             :          * TASK_WAKING such that we can unlock p->pi_lock before doing the
    3411             :          * enqueue, such as ttwu_queue_wakelist().
    3412             :          */
    3413       13862 :         p->state = TASK_WAKING;
    3414             : 
    3415             :         /*
    3416             :          * If the owning (remote) CPU is still in the middle of schedule() with
    3417             :          * this task as prev, considering queueing p on the remote CPUs wake_list
    3418             :          * which potentially sends an IPI instead of spinning on p->on_cpu to
    3419             :          * let the waker make forward progress. This is safe because IRQs are
    3420             :          * disabled and the IPI will deliver after on_cpu is cleared.
    3421             :          *
    3422             :          * Ensure we load task_cpu(p) after p->on_cpu:
    3423             :          *
    3424             :          * set_task_cpu(p, cpu);
    3425             :          *   STORE p->cpu = @cpu
    3426             :          * __schedule() (switch to task 'p')
    3427             :          *   LOCK rq->lock
    3428             :          *   smp_mb__after_spin_lock()          smp_cond_load_acquire(&p->on_cpu)
    3429             :          *   STORE p->on_cpu = 1             LOAD p->cpu
    3430             :          *
    3431             :          * to ensure we observe the correct CPU on which the task is currently
    3432             :          * scheduling.
    3433             :          */
    3434       13910 :         if (smp_load_acquire(&p->on_cpu) &&
    3435          48 :             ttwu_queue_wakelist(p, task_cpu(p), wake_flags | WF_ON_CPU))
    3436          48 :                 goto unlock;
    3437             : 
    3438             :         /*
    3439             :          * If the owning (remote) CPU is still in the middle of schedule() with
    3440             :          * this task as prev, wait until it's done referencing the task.
    3441             :          *
    3442             :          * Pairs with the smp_store_release() in finish_task().
    3443             :          *
    3444             :          * This ensures that tasks getting woken will be fully ordered against
    3445             :          * their previous state and preserve Program Order.
    3446             :          */
    3447       13813 :         smp_cond_load_acquire(&p->on_cpu, !VAL);
    3448             : 
    3449       13813 :         cpu = select_task_rq(p, p->wake_cpu, wake_flags | WF_TTWU);
    3450       13810 :         if (task_cpu(p) != cpu) {
    3451         110 :                 if (p->in_iowait) {
    3452           0 :                         delayacct_blkio_end(p);
    3453           0 :                         atomic_dec(&task_rq(p)->nr_iowait);
    3454             :                 }
    3455             : 
    3456         110 :                 wake_flags |= WF_MIGRATED;
    3457         110 :                 psi_ttwu_dequeue(p);
    3458         110 :                 set_task_cpu(p, cpu);
    3459             :         }
    3460             : #else
    3461             :         cpu = task_cpu(p);
    3462             : #endif /* CONFIG_SMP */
    3463             : 
    3464       13810 :         ttwu_queue(p, cpu, wake_flags);
    3465       15555 : unlock:
    3466       15555 :         raw_spin_unlock_irqrestore(&p->pi_lock, flags);
    3467       15554 : out:
    3468       15707 :         if (success)
    3469       14026 :                 ttwu_stat(p, task_cpu(p), wake_flags);
    3470       15707 :         preempt_enable();
    3471             : 
    3472       15707 :         return success;
    3473             : }
    3474             : 
    3475             : /**
    3476             :  * try_invoke_on_locked_down_task - Invoke a function on task in fixed state
    3477             :  * @p: Process for which the function is to be invoked, can be @current.
    3478             :  * @func: Function to invoke.
    3479             :  * @arg: Argument to function.
    3480             :  *
    3481             :  * If the specified task can be quickly locked into a definite state
    3482             :  * (either sleeping or on a given runqueue), arrange to keep it in that
    3483             :  * state while invoking @func(@arg).  This function can use ->on_rq and
    3484             :  * task_curr() to work out what the state is, if required.  Given that
    3485             :  * @func can be invoked with a runqueue lock held, it had better be quite
    3486             :  * lightweight.
    3487             :  *
    3488             :  * Returns:
    3489             :  *      @false if the task slipped out from under the locks.
    3490             :  *      @true if the task was locked onto a runqueue or is sleeping.
    3491             :  *              However, @func can override this by returning @false.
    3492             :  */
    3493           0 : bool try_invoke_on_locked_down_task(struct task_struct *p, bool (*func)(struct task_struct *t, void *arg), void *arg)
    3494             : {
    3495           0 :         struct rq_flags rf;
    3496           0 :         bool ret = false;
    3497           0 :         struct rq *rq;
    3498             : 
    3499           0 :         raw_spin_lock_irqsave(&p->pi_lock, rf.flags);
    3500           0 :         if (p->on_rq) {
    3501           0 :                 rq = __task_rq_lock(p, &rf);
    3502           0 :                 if (task_rq(p) == rq)
    3503           0 :                         ret = func(p, arg);
    3504           0 :                 rq_unlock(rq, &rf);
    3505             :         } else {
    3506           0 :                 switch (p->state) {
    3507             :                 case TASK_RUNNING:
    3508             :                 case TASK_WAKING:
    3509             :                         break;
    3510           0 :                 default:
    3511           0 :                         smp_rmb(); // See smp_rmb() comment in try_to_wake_up().
    3512           0 :                         if (!p->on_rq)
    3513           0 :                                 ret = func(p, arg);
    3514             :                 }
    3515             :         }
    3516           0 :         raw_spin_unlock_irqrestore(&p->pi_lock, rf.flags);
    3517           0 :         return ret;
    3518             : }
    3519             : 
    3520             : /**
    3521             :  * wake_up_process - Wake up a specific process
    3522             :  * @p: The process to be woken up.
    3523             :  *
    3524             :  * Attempt to wake up the nominated process and move it to the set of runnable
    3525             :  * processes.
    3526             :  *
    3527             :  * Return: 1 if the process was woken up, 0 if it was already running.
    3528             :  *
    3529             :  * This function executes a full memory barrier before accessing the task state.
    3530             :  */
    3531        9441 : int wake_up_process(struct task_struct *p)
    3532             : {
    3533        9441 :         return try_to_wake_up(p, TASK_NORMAL, 0);
    3534             : }
    3535             : EXPORT_SYMBOL(wake_up_process);
    3536             : 
    3537        1520 : int wake_up_state(struct task_struct *p, unsigned int state)
    3538             : {
    3539        1520 :         return try_to_wake_up(p, state, 0);
    3540             : }
    3541             : 
    3542             : /*
    3543             :  * Perform scheduler related setup for a newly forked process p.
    3544             :  * p is forked by current.
    3545             :  *
    3546             :  * __sched_fork() is basic setup used by init_idle() too:
    3547             :  */
    3548         990 : static void __sched_fork(unsigned long clone_flags, struct task_struct *p)
    3549             : {
    3550         990 :         p->on_rq                     = 0;
    3551             : 
    3552         990 :         p->se.on_rq                  = 0;
    3553         990 :         p->se.exec_start             = 0;
    3554         990 :         p->se.sum_exec_runtime               = 0;
    3555         990 :         p->se.prev_sum_exec_runtime  = 0;
    3556         990 :         p->se.nr_migrations          = 0;
    3557         990 :         p->se.vruntime                       = 0;
    3558         990 :         INIT_LIST_HEAD(&p->se.group_node);
    3559             : 
    3560             : #ifdef CONFIG_FAIR_GROUP_SCHED
    3561             :         p->se.cfs_rq                 = NULL;
    3562             : #endif
    3563             : 
    3564             : #ifdef CONFIG_SCHEDSTATS
    3565             :         /* Even if schedstat is disabled, there should not be garbage */
    3566             :         memset(&p->se.statistics, 0, sizeof(p->se.statistics));
    3567             : #endif
    3568             : 
    3569         990 :         RB_CLEAR_NODE(&p->dl.rb_node);
    3570         990 :         init_dl_task_timer(&p->dl);
    3571         990 :         init_dl_inactive_task_timer(&p->dl);
    3572         990 :         __dl_clear_params(p);
    3573             : 
    3574         990 :         INIT_LIST_HEAD(&p->rt.run_list);
    3575         990 :         p->rt.timeout                = 0;
    3576         990 :         p->rt.time_slice     = sched_rr_timeslice;
    3577         990 :         p->rt.on_rq          = 0;
    3578         990 :         p->rt.on_list                = 0;
    3579             : 
    3580             : #ifdef CONFIG_PREEMPT_NOTIFIERS
    3581             :         INIT_HLIST_HEAD(&p->preempt_notifiers);
    3582             : #endif
    3583             : 
    3584             : #ifdef CONFIG_COMPACTION
    3585         990 :         p->capture_control = NULL;
    3586             : #endif
    3587         990 :         init_numa_balancing(clone_flags, p);
    3588             : #ifdef CONFIG_SMP
    3589         990 :         p->wake_entry.u_flags = CSD_TYPE_TTWU;
    3590         990 :         p->migration_pending = NULL;
    3591             : #endif
    3592         990 : }
    3593             : 
    3594             : DEFINE_STATIC_KEY_FALSE(sched_numa_balancing);
    3595             : 
    3596             : #ifdef CONFIG_NUMA_BALANCING
    3597             : 
    3598             : void set_numabalancing_state(bool enabled)
    3599             : {
    3600             :         if (enabled)
    3601             :                 static_branch_enable(&sched_numa_balancing);
    3602             :         else
    3603             :                 static_branch_disable(&sched_numa_balancing);
    3604             : }
    3605             : 
    3606             : #ifdef CONFIG_PROC_SYSCTL
    3607             : int sysctl_numa_balancing(struct ctl_table *table, int write,
    3608             :                           void *buffer, size_t *lenp, loff_t *ppos)
    3609             : {
    3610             :         struct ctl_table t;
    3611             :         int err;
    3612             :         int state = static_branch_likely(&sched_numa_balancing);
    3613             : 
    3614             :         if (write && !capable(CAP_SYS_ADMIN))
    3615             :                 return -EPERM;
    3616             : 
    3617             :         t = *table;
    3618             :         t.data = &state;
    3619             :         err = proc_dointvec_minmax(&t, write, buffer, lenp, ppos);
    3620             :         if (err < 0)
    3621             :                 return err;
    3622             :         if (write)
    3623             :                 set_numabalancing_state(state);
    3624             :         return err;
    3625             : }
    3626             : #endif
    3627             : #endif
    3628             : 
    3629             : #ifdef CONFIG_SCHEDSTATS
    3630             : 
    3631             : DEFINE_STATIC_KEY_FALSE(sched_schedstats);
    3632             : static bool __initdata __sched_schedstats = false;
    3633             : 
    3634             : static void set_schedstats(bool enabled)
    3635             : {
    3636             :         if (enabled)
    3637             :                 static_branch_enable(&sched_schedstats);
    3638             :         else
    3639             :                 static_branch_disable(&sched_schedstats);
    3640             : }
    3641             : 
    3642             : void force_schedstat_enabled(void)
    3643             : {
    3644             :         if (!schedstat_enabled()) {
    3645             :                 pr_info("kernel profiling enabled schedstats, disable via kernel.sched_schedstats.\n");
    3646             :                 static_branch_enable(&sched_schedstats);
    3647             :         }
    3648             : }
    3649             : 
    3650             : static int __init setup_schedstats(char *str)
    3651             : {
    3652             :         int ret = 0;
    3653             :         if (!str)
    3654             :                 goto out;
    3655             : 
    3656             :         /*
    3657             :          * This code is called before jump labels have been set up, so we can't
    3658             :          * change the static branch directly just yet.  Instead set a temporary
    3659             :          * variable so init_schedstats() can do it later.
    3660             :          */
    3661             :         if (!strcmp(str, "enable")) {
    3662             :                 __sched_schedstats = true;
    3663             :                 ret = 1;
    3664             :         } else if (!strcmp(str, "disable")) {
    3665             :                 __sched_schedstats = false;
    3666             :                 ret = 1;
    3667             :         }
    3668             : out:
    3669             :         if (!ret)
    3670             :                 pr_warn("Unable to parse schedstats=\n");
    3671             : 
    3672             :         return ret;
    3673             : }
    3674             : __setup("schedstats=", setup_schedstats);
    3675             : 
    3676             : static void __init init_schedstats(void)
    3677             : {
    3678             :         set_schedstats(__sched_schedstats);
    3679             : }
    3680             : 
    3681             : #ifdef CONFIG_PROC_SYSCTL
    3682             : int sysctl_schedstats(struct ctl_table *table, int write, void *buffer,
    3683             :                 size_t *lenp, loff_t *ppos)
    3684             : {
    3685             :         struct ctl_table t;
    3686             :         int err;
    3687             :         int state = static_branch_likely(&sched_schedstats);
    3688             : 
    3689             :         if (write && !capable(CAP_SYS_ADMIN))
    3690             :                 return -EPERM;
    3691             : 
    3692             :         t = *table;
    3693             :         t.data = &state;
    3694             :         err = proc_dointvec_minmax(&t, write, buffer, lenp, ppos);
    3695             :         if (err < 0)
    3696             :                 return err;
    3697             :         if (write)
    3698             :                 set_schedstats(state);
    3699             :         return err;
    3700             : }
    3701             : #endif /* CONFIG_PROC_SYSCTL */
    3702             : #else  /* !CONFIG_SCHEDSTATS */
    3703           1 : static inline void init_schedstats(void) {}
    3704             : #endif /* CONFIG_SCHEDSTATS */
    3705             : 
    3706             : /*
    3707             :  * fork()/clone()-time setup:
    3708             :  */
    3709         980 : int sched_fork(unsigned long clone_flags, struct task_struct *p)
    3710             : {
    3711         980 :         unsigned long flags;
    3712             : 
    3713         980 :         __sched_fork(clone_flags, p);
    3714             :         /*
    3715             :          * We mark the process as NEW here. This guarantees that
    3716             :          * nobody will actually run it, and a signal or other external
    3717             :          * event cannot wake it up and insert it on the runqueue either.
    3718             :          */
    3719         980 :         p->state = TASK_NEW;
    3720             : 
    3721             :         /*
    3722             :          * Make sure we do not leak PI boosting priority to the child.
    3723             :          */
    3724         980 :         p->prio = current->normal_prio;
    3725             : 
    3726         980 :         uclamp_fork(p);
    3727             : 
    3728             :         /*
    3729             :          * Revert to default priority/policy on fork if requested.
    3730             :          */
    3731         980 :         if (unlikely(p->sched_reset_on_fork)) {
    3732           0 :                 if (task_has_dl_policy(p) || task_has_rt_policy(p)) {
    3733           0 :                         p->policy = SCHED_NORMAL;
    3734           0 :                         p->static_prio = NICE_TO_PRIO(0);
    3735           0 :                         p->rt_priority = 0;
    3736           0 :                 } else if (PRIO_TO_NICE(p->static_prio) < 0)
    3737           0 :                         p->static_prio = NICE_TO_PRIO(0);
    3738             : 
    3739           0 :                 p->prio = p->normal_prio = __normal_prio(p);
    3740           0 :                 set_load_weight(p, false);
    3741             : 
    3742             :                 /*
    3743             :                  * We don't need the reset flag anymore after the fork. It has
    3744             :                  * fulfilled its duty:
    3745             :                  */
    3746           0 :                 p->sched_reset_on_fork = 0;
    3747             :         }
    3748             : 
    3749         980 :         if (dl_prio(p->prio))
    3750             :                 return -EAGAIN;
    3751         980 :         else if (rt_prio(p->prio))
    3752           0 :                 p->sched_class = &rt_sched_class;
    3753             :         else
    3754         980 :                 p->sched_class = &fair_sched_class;
    3755             : 
    3756         980 :         init_entity_runnable_average(&p->se);
    3757             : 
    3758             :         /*
    3759             :          * The child is not yet in the pid-hash so no cgroup attach races,
    3760             :          * and the cgroup is pinned to this child due to cgroup_fork()
    3761             :          * is ran before sched_fork().
    3762             :          *
    3763             :          * Silence PROVE_RCU.
    3764             :          */
    3765         980 :         raw_spin_lock_irqsave(&p->pi_lock, flags);
    3766         980 :         rseq_migrate(p);
    3767             :         /*
    3768             :          * We're setting the CPU for the first time, we don't migrate,
    3769             :          * so use __set_task_cpu().
    3770             :          */
    3771         980 :         __set_task_cpu(p, smp_processor_id());
    3772         980 :         if (p->sched_class->task_fork)
    3773         980 :                 p->sched_class->task_fork(p);
    3774         980 :         raw_spin_unlock_irqrestore(&p->pi_lock, flags);
    3775             : 
    3776             : #ifdef CONFIG_SCHED_INFO
    3777         980 :         if (likely(sched_info_on()))
    3778         980 :                 memset(&p->sched_info, 0, sizeof(p->sched_info));
    3779             : #endif
    3780             : #if defined(CONFIG_SMP)
    3781         980 :         p->on_cpu = 0;
    3782             : #endif
    3783         980 :         init_task_preempt_count(p);
    3784             : #ifdef CONFIG_SMP
    3785         980 :         plist_node_init(&p->pushable_tasks, MAX_PRIO);
    3786         980 :         RB_CLEAR_NODE(&p->pushable_dl_tasks);
    3787             : #endif
    3788         980 :         return 0;
    3789             : }
    3790             : 
    3791         980 : void sched_post_fork(struct task_struct *p)
    3792             : {
    3793         980 :         uclamp_post_fork(p);
    3794         980 : }
    3795             : 
    3796          10 : unsigned long to_ratio(u64 period, u64 runtime)
    3797             : {
    3798          10 :         if (runtime == RUNTIME_INF)
    3799             :                 return BW_UNIT;
    3800             : 
    3801             :         /*
    3802             :          * Doing this here saves a lot of checks in all
    3803             :          * the calling paths, and returning zero seems
    3804             :          * safe for them anyway.
    3805             :          */
    3806          10 :         if (period == 0)
    3807             :                 return 0;
    3808             : 
    3809          10 :         return div64_u64(runtime << BW_SHIFT, period);
    3810             : }
    3811             : 
    3812             : /*
    3813             :  * wake_up_new_task - wake up a newly created task for the first time.
    3814             :  *
    3815             :  * This function will do some initial scheduler statistics housekeeping
    3816             :  * that must be done for every newly created context, then puts the task
    3817             :  * on the runqueue and wakes it.
    3818             :  */
    3819         977 : void wake_up_new_task(struct task_struct *p)
    3820             : {
    3821         977 :         struct rq_flags rf;
    3822         977 :         struct rq *rq;
    3823             : 
    3824         977 :         raw_spin_lock_irqsave(&p->pi_lock, rf.flags);
    3825         977 :         p->state = TASK_RUNNING;
    3826             : #ifdef CONFIG_SMP
    3827             :         /*
    3828             :          * Fork balancing, do it here and not earlier because:
    3829             :          *  - cpus_ptr can change in the fork path
    3830             :          *  - any previously selected CPU might disappear through hotplug
    3831             :          *
    3832             :          * Use __set_task_cpu() to avoid calling sched_class::migrate_task_rq,
    3833             :          * as we're not fully set-up yet.
    3834             :          */
    3835         977 :         p->recent_used_cpu = task_cpu(p);
    3836         977 :         rseq_migrate(p);
    3837         977 :         __set_task_cpu(p, select_task_rq(p, task_cpu(p), WF_FORK));
    3838             : #endif
    3839         977 :         rq = __task_rq_lock(p, &rf);
    3840         977 :         update_rq_clock(rq);
    3841         977 :         post_init_entity_util_avg(p);
    3842             : 
    3843         977 :         activate_task(rq, p, ENQUEUE_NOCLOCK);
    3844         977 :         trace_sched_wakeup_new(p);
    3845         977 :         check_preempt_curr(rq, p, WF_FORK);
    3846             : #ifdef CONFIG_SMP
    3847         977 :         if (p->sched_class->task_woken) {
    3848             :                 /*
    3849             :                  * Nothing relies on rq->lock after this, so it's fine to
    3850             :                  * drop it.
    3851             :                  */
    3852           0 :                 rq_unpin_lock(rq, &rf);
    3853           0 :                 p->sched_class->task_woken(rq, p);
    3854           0 :                 rq_repin_lock(rq, &rf);
    3855             :         }
    3856             : #endif
    3857         977 :         task_rq_unlock(rq, p, &rf);
    3858         977 : }
    3859             : 
    3860             : #ifdef CONFIG_PREEMPT_NOTIFIERS
    3861             : 
    3862             : static DEFINE_STATIC_KEY_FALSE(preempt_notifier_key);
    3863             : 
    3864             : void preempt_notifier_inc(void)
    3865             : {
    3866             :         static_branch_inc(&preempt_notifier_key);
    3867             : }
    3868             : EXPORT_SYMBOL_GPL(preempt_notifier_inc);
    3869             : 
    3870             : void preempt_notifier_dec(void)
    3871             : {
    3872             :         static_branch_dec(&preempt_notifier_key);
    3873             : }
    3874             : EXPORT_SYMBOL_GPL(preempt_notifier_dec);
    3875             : 
    3876             : /**
    3877             :  * preempt_notifier_register - tell me when current is being preempted & rescheduled
    3878             :  * @notifier: notifier struct to register
    3879             :  */
    3880             : void preempt_notifier_register(struct preempt_notifier *notifier)
    3881             : {
    3882             :         if (!static_branch_unlikely(&preempt_notifier_key))
    3883             :                 WARN(1, "registering preempt_notifier while notifiers disabled\n");
    3884             : 
    3885             :         hlist_add_head(&notifier->link, &current->preempt_notifiers);
    3886             : }
    3887             : EXPORT_SYMBOL_GPL(preempt_notifier_register);
    3888             : 
    3889             : /**
    3890             :  * preempt_notifier_unregister - no longer interested in preemption notifications
    3891             :  * @notifier: notifier struct to unregister
    3892             :  *
    3893             :  * This is *not* safe to call from within a preemption notifier.
    3894             :  */
    3895             : void preempt_notifier_unregister(struct preempt_notifier *notifier)
    3896             : {
    3897             :         hlist_del(&notifier->link);
    3898             : }
    3899             : EXPORT_SYMBOL_GPL(preempt_notifier_unregister);
    3900             : 
    3901             : static void __fire_sched_in_preempt_notifiers(struct task_struct *curr)
    3902             : {
    3903             :         struct preempt_notifier *notifier;
    3904             : 
    3905             :         hlist_for_each_entry(notifier, &curr->preempt_notifiers, link)
    3906             :                 notifier->ops->sched_in(notifier, raw_smp_processor_id());
    3907             : }
    3908             : 
    3909             : static __always_inline void fire_sched_in_preempt_notifiers(struct task_struct *curr)
    3910             : {
    3911             :         if (static_branch_unlikely(&preempt_notifier_key))
    3912             :                 __fire_sched_in_preempt_notifiers(curr);
    3913             : }
    3914             : 
    3915             : static void
    3916             : __fire_sched_out_preempt_notifiers(struct task_struct *curr,
    3917             :                                    struct task_struct *next)
    3918             : {
    3919             :         struct preempt_notifier *notifier;
    3920             : 
    3921             :         hlist_for_each_entry(notifier, &curr->preempt_notifiers, link)
    3922             :                 notifier->ops->sched_out(notifier, next);
    3923             : }
    3924             : 
    3925             : static __always_inline void
    3926             : fire_sched_out_preempt_notifiers(struct task_struct *curr,
    3927             :                                  struct task_struct *next)
    3928             : {
    3929             :         if (static_branch_unlikely(&preempt_notifier_key))
    3930             :                 __fire_sched_out_preempt_notifiers(curr, next);
    3931             : }
    3932             : 
    3933             : #else /* !CONFIG_PREEMPT_NOTIFIERS */
    3934             : 
    3935       26515 : static inline void fire_sched_in_preempt_notifiers(struct task_struct *curr)
    3936             : {
    3937       26515 : }
    3938             : 
    3939             : static inline void
    3940       26512 : fire_sched_out_preempt_notifiers(struct task_struct *curr,
    3941             :                                  struct task_struct *next)
    3942             : {
    3943       26512 : }
    3944             : 
    3945             : #endif /* CONFIG_PREEMPT_NOTIFIERS */
    3946             : 
    3947       26512 : static inline void prepare_task(struct task_struct *next)
    3948             : {
    3949             : #ifdef CONFIG_SMP
    3950             :         /*
    3951             :          * Claim the task as running, we do this before switching to it
    3952             :          * such that any running task will have this set.
    3953             :          *
    3954             :          * See the ttwu() WF_ON_CPU case and its ordering comment.
    3955             :          */
    3956       26512 :         WRITE_ONCE(next->on_cpu, 1);
    3957             : #endif
    3958             : }
    3959             : 
    3960       26512 : static inline void finish_task(struct task_struct *prev)
    3961             : {
    3962             : #ifdef CONFIG_SMP
    3963             :         /*
    3964             :          * This must be the very last reference to @prev from this CPU. After
    3965             :          * p->on_cpu is cleared, the task can be moved to a different CPU. We
    3966             :          * must ensure this doesn't happen until the switch is completely
    3967             :          * finished.
    3968             :          *
    3969             :          * In particular, the load of prev->state in finish_task_switch() must
    3970             :          * happen before this.
    3971             :          *
    3972             :          * Pairs with the smp_cond_load_acquire() in try_to_wake_up().
    3973             :          */
    3974       53025 :         smp_store_release(&prev->on_cpu, 0);
    3975             : #endif
    3976             : }
    3977             : 
    3978             : #ifdef CONFIG_SMP
    3979             : 
    3980       27956 : static void do_balance_callbacks(struct rq *rq, struct callback_head *head)
    3981             : {
    3982       27956 :         void (*func)(struct rq *rq);
    3983       27956 :         struct callback_head *next;
    3984             : 
    3985       55921 :         lockdep_assert_held(&rq->lock);
    3986             : 
    3987       27966 :         while (head) {
    3988           0 :                 func = (void (*)(struct rq *))head->func;
    3989           0 :                 next = head->next;
    3990           0 :                 head->next = NULL;
    3991           0 :                 head = next;
    3992             : 
    3993           0 :                 func(rq);
    3994             :         }
    3995       27966 : }
    3996             : 
    3997             : static void balance_push(struct rq *rq);
    3998             : 
    3999             : struct callback_head balance_push_callback = {
    4000             :         .next = NULL,
    4001             :         .func = (void (*)(struct callback_head *))balance_push,
    4002             : };
    4003             : 
    4004       27965 : static inline struct callback_head *splice_balance_callbacks(struct rq *rq)
    4005             : {
    4006       27965 :         struct callback_head *head = rq->balance_callback;
    4007             : 
    4008       55931 :         lockdep_assert_held(&rq->lock);
    4009       27966 :         if (head)
    4010           0 :                 rq->balance_callback = NULL;
    4011             : 
    4012       27966 :         return head;
    4013             : }
    4014             : 
    4015       27959 : static void __balance_callbacks(struct rq *rq)
    4016             : {
    4017       27959 :         do_balance_callbacks(rq, splice_balance_callbacks(rq));
    4018       27966 : }
    4019             : 
    4020           4 : static inline void balance_callbacks(struct rq *rq, struct callback_head *head)
    4021             : {
    4022           4 :         unsigned long flags;
    4023             : 
    4024           4 :         if (unlikely(head)) {
    4025           0 :                 raw_spin_lock_irqsave(&rq->lock, flags);
    4026           0 :                 do_balance_callbacks(rq, head);
    4027           0 :                 raw_spin_unlock_irqrestore(&rq->lock, flags);
    4028             :         }
    4029           4 : }
    4030             : 
    4031             : #else
    4032             : 
    4033             : static inline void __balance_callbacks(struct rq *rq)
    4034             : {
    4035             : }
    4036             : 
    4037             : static inline struct callback_head *splice_balance_callbacks(struct rq *rq)
    4038             : {
    4039             :         return NULL;
    4040             : }
    4041             : 
    4042             : static inline void balance_callbacks(struct rq *rq, struct callback_head *head)
    4043             : {
    4044             : }
    4045             : 
    4046             : #endif
    4047             : 
    4048             : static inline void
    4049       26511 : prepare_lock_switch(struct rq *rq, struct task_struct *next, struct rq_flags *rf)
    4050             : {
    4051             :         /*
    4052             :          * Since the runqueue lock will be released by the next
    4053             :          * task (which is an invalid locking op but in the case
    4054             :          * of the scheduler it's an obvious special-case), so we
    4055             :          * do an early lockdep release here:
    4056             :          */
    4057       26511 :         rq_unpin_lock(rq, rf);
    4058       26511 :         spin_release(&rq->lock.dep_map, _THIS_IP_);
    4059             : #ifdef CONFIG_DEBUG_SPINLOCK
    4060             :         /* this is a valid case when another task releases the spinlock */
    4061       26507 :         rq->lock.owner = next;
    4062             : #endif
    4063       26507 : }
    4064             : 
    4065       26509 : static inline void finish_lock_switch(struct rq *rq)
    4066             : {
    4067             :         /*
    4068             :          * If we are tracking spinlock dependencies then we have to
    4069             :          * fix up the runqueue lock - which gets 'carried over' from
    4070             :          * prev into current:
    4071             :          */
    4072       26509 :         spin_acquire(&rq->lock.dep_map, 0, 0, _THIS_IP_);
    4073       26508 :         __balance_callbacks(rq);
    4074       26514 :         raw_spin_unlock_irq(&rq->lock);
    4075       26514 : }
    4076             : 
    4077             : /*
    4078             :  * NOP if the arch has not defined these:
    4079             :  */
    4080             : 
    4081             : #ifndef prepare_arch_switch
    4082             : # define prepare_arch_switch(next)      do { } while (0)
    4083             : #endif
    4084             : 
    4085             : #ifndef finish_arch_post_lock_switch
    4086             : # define finish_arch_post_lock_switch() do { } while (0)
    4087             : #endif
    4088             : 
    4089       26512 : static inline void kmap_local_sched_out(void)
    4090             : {
    4091             : #ifdef CONFIG_KMAP_LOCAL
    4092             :         if (unlikely(current->kmap_ctrl.idx))
    4093             :                 __kmap_local_sched_out();
    4094             : #endif
    4095       26512 : }
    4096             : 
    4097       26515 : static inline void kmap_local_sched_in(void)
    4098             : {
    4099             : #ifdef CONFIG_KMAP_LOCAL
    4100             :         if (unlikely(current->kmap_ctrl.idx))
    4101             :                 __kmap_local_sched_in();
    4102             : #endif
    4103       26515 : }
    4104             : 
    4105             : /**
    4106             :  * prepare_task_switch - prepare to switch tasks
    4107             :  * @rq: the runqueue preparing to switch
    4108             :  * @prev: the current task that is being switched out
    4109             :  * @next: the task we are going to switch to.
    4110             :  *
    4111             :  * This is called with the rq lock held and interrupts off. It must
    4112             :  * be paired with a subsequent finish_task_switch after the context
    4113             :  * switch.
    4114             :  *
    4115             :  * prepare_task_switch sets up locking and calls architecture specific
    4116             :  * hooks.
    4117             :  */
    4118             : static inline void
    4119       26511 : prepare_task_switch(struct rq *rq, struct task_struct *prev,
    4120             :                     struct task_struct *next)
    4121             : {
    4122       26511 :         kcov_prepare_switch(prev);
    4123       26511 :         sched_info_switch(rq, prev, next);
    4124       26511 :         perf_event_task_sched_out(prev, next);
    4125       26512 :         rseq_preempt(prev);
    4126       26512 :         fire_sched_out_preempt_notifiers(prev, next);
    4127       26512 :         kmap_local_sched_out();
    4128       26512 :         prepare_task(next);
    4129       26512 :         prepare_arch_switch(next);
    4130       26512 : }
    4131             : 
    4132             : /**
    4133             :  * finish_task_switch - clean up after a task-switch
    4134             :  * @prev: the thread we just switched away from.
    4135             :  *
    4136             :  * finish_task_switch must be called after the context switch, paired
    4137             :  * with a prepare_task_switch call before the context switch.
    4138             :  * finish_task_switch will reconcile locking set up by prepare_task_switch,
    4139             :  * and do any other architecture-specific cleanup actions.
    4140             :  *
    4141             :  * Note that we may have delayed dropping an mm in context_switch(). If
    4142             :  * so, we finish that here outside of the runqueue lock. (Doing it
    4143             :  * with the lock held can cause deadlocks; see schedule() for
    4144             :  * details.)
    4145             :  *
    4146             :  * The context switch have flipped the stack from under us and restored the
    4147             :  * local variables which were saved when this task called schedule() in the
    4148             :  * past. prev == current is still correct but we need to recalculate this_rq
    4149             :  * because prev may have moved to another CPU.
    4150             :  */
    4151       26508 : static struct rq *finish_task_switch(struct task_struct *prev)
    4152             :         __releases(rq->lock)
    4153             : {
    4154       26508 :         struct rq *rq = this_rq();
    4155       26509 :         struct mm_struct *mm = rq->prev_mm;
    4156       26509 :         long prev_state;
    4157             : 
    4158             :         /*
    4159             :          * The previous task will have left us with a preempt_count of 2
    4160             :          * because it left us after:
    4161             :          *
    4162             :          *      schedule()
    4163             :          *        preempt_disable();                    // 1
    4164             :          *        __schedule()
    4165             :          *          raw_spin_lock_irq(&rq->lock) // 2
    4166             :          *
    4167             :          * Also, see FORK_PREEMPT_COUNT.
    4168             :          */
    4169       26509 :         if (WARN_ONCE(preempt_count() != 2*PREEMPT_DISABLE_OFFSET,
    4170             :                       "corrupted preempt_count: %s/%d/0x%x\n",
    4171             :                       current->comm, current->pid, preempt_count()))
    4172           0 :                 preempt_count_set(FORK_PREEMPT_COUNT);
    4173             : 
    4174       26509 :         rq->prev_mm = NULL;
    4175             : 
    4176             :         /*
    4177             :          * A task struct has one reference for the use as "current".
    4178             :          * If a task dies, then it sets TASK_DEAD in tsk->state and calls
    4179             :          * schedule one last time. The schedule call will never return, and
    4180             :          * the scheduled task must drop that reference.
    4181             :          *
    4182             :          * We must observe prev->state before clearing prev->on_cpu (in
    4183             :          * finish_task), otherwise a concurrent wakeup can get prev
    4184             :          * running on another CPU and we could rave with its RUNNING -> DEAD
    4185             :          * transition, resulting in a double drop.
    4186             :          */
    4187       26509 :         prev_state = prev->state;
    4188       26509 :         vtime_task_switch(prev);
    4189       26509 :         perf_event_task_sched_in(prev, current);
    4190       26512 :         finish_task(prev);
    4191       26513 :         finish_lock_switch(rq);
    4192       26515 :         finish_arch_post_lock_switch();
    4193       26515 :         kcov_finish_switch(current);
    4194             :         /*
    4195             :          * kmap_local_sched_out() is invoked with rq::lock held and
    4196             :          * interrupts disabled. There is no requirement for that, but the
    4197             :          * sched out code does not have an interrupt enabled section.
    4198             :          * Restoring the maps on sched in does not require interrupts being
    4199             :          * disabled either.
    4200             :          */
    4201       26515 :         kmap_local_sched_in();
    4202             : 
    4203       26515 :         fire_sched_in_preempt_notifiers(current);
    4204             :         /*
    4205             :          * When switching through a kernel thread, the loop in
    4206             :          * membarrier_{private,global}_expedited() may have observed that
    4207             :          * kernel thread and not issued an IPI. It is therefore possible to
    4208             :          * schedule between user->kernel->user threads without passing though
    4209             :          * switch_mm(). Membarrier requires a barrier after storing to
    4210             :          * rq->curr, before returning to userspace, so provide them here:
    4211             :          *
    4212             :          * - a full memory barrier for {PRIVATE,GLOBAL}_EXPEDITED, implicitly
    4213             :          *   provided by mmdrop(),
    4214             :          * - a sync_core for SYNC_CORE.
    4215             :          */
    4216       26515 :         if (mm) {
    4217        7345 :                 membarrier_mm_sync_core_before_usermode(mm);
    4218        7345 :                 mmdrop(mm);
    4219             :         }
    4220       26516 :         if (unlikely(prev_state == TASK_DEAD)) {
    4221         900 :                 if (prev->sched_class->task_dead)
    4222         900 :                         prev->sched_class->task_dead(prev);
    4223             : 
    4224             :                 /*
    4225             :                  * Remove function-return probe instances associated with this
    4226             :                  * task and put them back on the free list.
    4227             :                  */
    4228         900 :                 kprobe_flush_task(prev);
    4229             : 
    4230             :                 /* Task is done with its stack. */
    4231         900 :                 put_task_stack(prev);
    4232             : 
    4233         900 :                 put_task_struct_rcu_user(prev);
    4234             :         }
    4235             : 
    4236       26516 :         tick_nohz_task_switch();
    4237       26516 :         return rq;
    4238             : }
    4239             : 
    4240             : /**
    4241             :  * schedule_tail - first thing a freshly forked thread must call.
    4242             :  * @prev: the thread we just switched away from.
    4243             :  */
    4244         976 : asmlinkage __visible void schedule_tail(struct task_struct *prev)
    4245             :         __releases(rq->lock)
    4246             : {
    4247         976 :         struct rq *rq;
    4248             : 
    4249             :         /*
    4250             :          * New tasks start with FORK_PREEMPT_COUNT, see there and
    4251             :          * finish_task_switch() for details.
    4252             :          *
    4253             :          * finish_task_switch() will drop rq->lock() and lower preempt_count
    4254             :          * and the preempt_enable() will end up enabling preemption (on
    4255             :          * PREEMPT_COUNT kernels).
    4256             :          */
    4257             : 
    4258         976 :         rq = finish_task_switch(prev);
    4259         977 :         preempt_enable();
    4260             : 
    4261         977 :         if (current->set_child_tid)
    4262         917 :                 put_user(task_pid_vnr(current), current->set_child_tid);
    4263             : 
    4264         977 :         calculate_sigpending();
    4265         977 : }
    4266             : 
    4267             : /*
    4268             :  * context_switch - switch to the new MM and the new thread's register state.
    4269             :  */
    4270             : static __always_inline struct rq *
    4271       26512 : context_switch(struct rq *rq, struct task_struct *prev,
    4272             :                struct task_struct *next, struct rq_flags *rf)
    4273             : {
    4274       26512 :         prepare_task_switch(rq, prev, next);
    4275             : 
    4276             :         /*
    4277             :          * For paravirt, this is coupled with an exit in switch_to to
    4278             :          * combine the page table reload and the switch backend into
    4279             :          * one hypercall.
    4280             :          */
    4281       26512 :         arch_start_context_switch(prev);
    4282             : 
    4283             :         /*
    4284             :          * kernel -> kernel   lazy + transfer active
    4285             :          *   user -> kernel   lazy + mmgrab() active
    4286             :          *
    4287             :          * kernel ->   user   switch + mmdrop() active
    4288             :          *   user ->   user   switch
    4289             :          */
    4290       26512 :         if (!next->mm) {                                // to kernel
    4291       16097 :                 enter_lazy_tlb(prev->active_mm, next);
    4292             : 
    4293       16097 :                 next->active_mm = prev->active_mm;
    4294       16097 :                 if (prev->mm)                           // from user
    4295        6446 :                         mmgrab(prev->active_mm);
    4296             :                 else
    4297        9651 :                         prev->active_mm = NULL;
    4298             :         } else {                                        // to user
    4299       10415 :                 membarrier_switch_mm(rq, prev->active_mm, next->mm);
    4300             :                 /*
    4301             :                  * sys_membarrier() requires an smp_mb() between setting
    4302             :                  * rq->curr / membarrier_switch_mm() and returning to userspace.
    4303             :                  *
    4304             :                  * The below provides this either through switch_mm(), or in
    4305             :                  * case 'prev->active_mm == next->mm' through
    4306             :                  * finish_task_switch()'s mmdrop().
    4307             :                  */
    4308       10415 :                 switch_mm_irqs_off(prev->active_mm, next->mm, next);
    4309             : 
    4310       10415 :                 if (!prev->mm) {                        // from kernel
    4311             :                         /* will mmdrop() in finish_task_switch(). */
    4312        7346 :                         rq->prev_mm = prev->active_mm;
    4313        7346 :                         prev->active_mm = NULL;
    4314             :                 }
    4315             :         }
    4316             : 
    4317       26512 :         rq->clock_update_flags &= ~(RQCF_ACT_SKIP|RQCF_REQ_SKIP);
    4318             : 
    4319       26512 :         prepare_lock_switch(rq, next, rf);
    4320             : 
    4321             :         /* Here we just switch the register state and the stack. */
    4322       26507 :         switch_to(prev, next, prev);
    4323       25536 :         barrier();
    4324             : 
    4325       25537 :         return finish_task_switch(prev);
    4326             : }
    4327             : 
    4328             : /*
    4329             :  * nr_running and nr_context_switches:
    4330             :  *
    4331             :  * externally visible scheduler statistics: current number of runnable
    4332             :  * threads, total number of context switches performed since bootup.
    4333             :  */
    4334           0 : unsigned long nr_running(void)
    4335             : {
    4336           0 :         unsigned long i, sum = 0;
    4337             : 
    4338           0 :         for_each_online_cpu(i)
    4339           0 :                 sum += cpu_rq(i)->nr_running;
    4340             : 
    4341           0 :         return sum;
    4342             : }
    4343             : 
    4344             : /*
    4345             :  * Check if only the current task is running on the CPU.
    4346             :  *
    4347             :  * Caution: this function does not check that the caller has disabled
    4348             :  * preemption, thus the result might have a time-of-check-to-time-of-use
    4349             :  * race.  The caller is responsible to use it correctly, for example:
    4350             :  *
    4351             :  * - from a non-preemptible section (of course)
    4352             :  *
    4353             :  * - from a thread that is bound to a single CPU
    4354             :  *
    4355             :  * - in a loop with very short iterations (e.g. a polling loop)
    4356             :  */
    4357           0 : bool single_task_running(void)
    4358             : {
    4359           0 :         return raw_rq()->nr_running == 1;
    4360             : }
    4361             : EXPORT_SYMBOL(single_task_running);
    4362             : 
    4363           1 : unsigned long long nr_context_switches(void)
    4364             : {
    4365           1 :         int i;
    4366           1 :         unsigned long long sum = 0;
    4367             : 
    4368           5 :         for_each_possible_cpu(i)
    4369           4 :                 sum += cpu_rq(i)->nr_switches;
    4370             : 
    4371           1 :         return sum;
    4372             : }
    4373             : 
    4374             : /*
    4375             :  * Consumers of these two interfaces, like for example the cpuidle menu
    4376             :  * governor, are using nonsensical data. Preferring shallow idle state selection
    4377             :  * for a CPU that has IO-wait which might not even end up running the task when
    4378             :  * it does become runnable.
    4379             :  */
    4380             : 
    4381       14964 : unsigned long nr_iowait_cpu(int cpu)
    4382             : {
    4383       14964 :         return atomic_read(&cpu_rq(cpu)->nr_iowait);
    4384             : }
    4385             : 
    4386             : /*
    4387             :  * IO-wait accounting, and how it's mostly bollocks (on SMP).
    4388             :  *
    4389             :  * The idea behind IO-wait account is to account the idle time that we could
    4390             :  * have spend running if it were not for IO. That is, if we were to improve the
    4391             :  * storage performance, we'd have a proportional reduction in IO-wait time.
    4392             :  *
    4393             :  * This all works nicely on UP, where, when a task blocks on IO, we account
    4394             :  * idle time as IO-wait, because if the storage were faster, it could've been
    4395             :  * running and we'd not be idle.
    4396             :  *
    4397             :  * This has been extended to SMP, by doing the same for each CPU. This however
    4398             :  * is broken.
    4399             :  *
    4400             :  * Imagine for instance the case where two tasks block on one CPU, only the one
    4401             :  * CPU will have IO-wait accounted, while the other has regular idle. Even
    4402             :  * though, if the storage were faster, both could've ran at the same time,
    4403             :  * utilising both CPUs.
    4404             :  *
    4405             :  * This means, that when looking globally, the current IO-wait accounting on
    4406             :  * SMP is a lower bound, by reason of under accounting.
    4407             :  *
    4408             :  * Worse, since the numbers are provided per CPU, they are sometimes
    4409             :  * interpreted per CPU, and that is nonsensical. A blocked task isn't strictly
    4410             :  * associated with any one particular CPU, it can wake to another CPU than it
    4411             :  * blocked on. This means the per CPU IO-wait number is meaningless.
    4412             :  *
    4413             :  * Task CPU affinities can make all that even more 'interesting'.
    4414             :  */
    4415             : 
    4416           0 : unsigned long nr_iowait(void)
    4417             : {
    4418           0 :         unsigned long i, sum = 0;
    4419             : 
    4420           0 :         for_each_possible_cpu(i)
    4421           0 :                 sum += nr_iowait_cpu(i);
    4422             : 
    4423           0 :         return sum;
    4424             : }
    4425             : 
    4426             : #ifdef CONFIG_SMP
    4427             : 
    4428             : /*
    4429             :  * sched_exec - execve() is a valuable balancing opportunity, because at
    4430             :  * this point the task has the smallest effective memory and cache footprint.
    4431             :  */
    4432         615 : void sched_exec(void)
    4433             : {
    4434         615 :         struct task_struct *p = current;
    4435         615 :         unsigned long flags;
    4436         615 :         int dest_cpu;
    4437             : 
    4438         615 :         raw_spin_lock_irqsave(&p->pi_lock, flags);
    4439         615 :         dest_cpu = p->sched_class->select_task_rq(p, task_cpu(p), WF_EXEC);
    4440         615 :         if (dest_cpu == smp_processor_id())
    4441         584 :                 goto unlock;
    4442             : 
    4443          31 :         if (likely(cpu_active(dest_cpu))) {
    4444          31 :                 struct migration_arg arg = { p, dest_cpu };
    4445             : 
    4446          31 :                 raw_spin_unlock_irqrestore(&p->pi_lock, flags);
    4447          31 :                 stop_one_cpu(task_cpu(p), migration_cpu_stop, &arg);
    4448          31 :                 return;
    4449             :         }
    4450           0 : unlock:
    4451         584 :         raw_spin_unlock_irqrestore(&p->pi_lock, flags);
    4452             : }
    4453             : 
    4454             : #endif
    4455             : 
    4456             : DEFINE_PER_CPU(struct kernel_stat, kstat);
    4457             : DEFINE_PER_CPU(struct kernel_cpustat, kernel_cpustat);
    4458             : 
    4459             : EXPORT_PER_CPU_SYMBOL(kstat);
    4460             : EXPORT_PER_CPU_SYMBOL(kernel_cpustat);
    4461             : 
    4462             : /*
    4463             :  * The function fair_sched_class.update_curr accesses the struct curr
    4464             :  * and its field curr->exec_start; when called from task_sched_runtime(),
    4465             :  * we observe a high rate of cache misses in practice.
    4466             :  * Prefetching this data results in improved performance.
    4467             :  */
    4468          49 : static inline void prefetch_curr_exec_start(struct task_struct *p)
    4469             : {
    4470             : #ifdef CONFIG_FAIR_GROUP_SCHED
    4471             :         struct sched_entity *curr = (&p->se)->cfs_rq->curr;
    4472             : #else
    4473          49 :         struct sched_entity *curr = (&task_rq(p)->cfs)->curr;
    4474             : #endif
    4475          49 :         prefetch(curr);
    4476          49 :         prefetch(&curr->exec_start);
    4477             : }
    4478             : 
    4479             : /*
    4480             :  * Return accounted runtime for the task.
    4481             :  * In case the task is currently running, return the runtime plus current's
    4482             :  * pending runtime that have not been accounted yet.
    4483             :  */
    4484          49 : unsigned long long task_sched_runtime(struct task_struct *p)
    4485             : {
    4486          49 :         struct rq_flags rf;
    4487          49 :         struct rq *rq;
    4488          49 :         u64 ns;
    4489             : 
    4490             : #if defined(CONFIG_64BIT) && defined(CONFIG_SMP)
    4491             :         /*
    4492             :          * 64-bit doesn't need locks to atomically read a 64-bit value.
    4493             :          * So we have a optimization chance when the task's delta_exec is 0.
    4494             :          * Reading ->on_cpu is racy, but this is ok.
    4495             :          *
    4496             :          * If we race with it leaving CPU, we'll take a lock. So we're correct.
    4497             :          * If we race with it entering CPU, unaccounted time is 0. This is
    4498             :          * indistinguishable from the read occurring a few cycles earlier.
    4499             :          * If we see ->on_cpu without ->on_rq, the task is leaving, and has
    4500             :          * been accounted, so we're correct here as well.
    4501             :          */
    4502          49 :         if (!p->on_cpu || !task_on_rq_queued(p))
    4503           0 :                 return p->se.sum_exec_runtime;
    4504             : #endif
    4505             : 
    4506          49 :         rq = task_rq_lock(p, &rf);
    4507             :         /*
    4508             :          * Must be ->curr _and_ ->on_rq.  If dequeued, we would
    4509             :          * project cycles that may never be accounted to this
    4510             :          * thread, breaking clock_gettime().
    4511             :          */
    4512          49 :         if (task_current(rq, p) && task_on_rq_queued(p)) {
    4513          49 :                 prefetch_curr_exec_start(p);
    4514          49 :                 update_rq_clock(rq);
    4515          49 :                 p->sched_class->update_curr(rq);
    4516             :         }
    4517          49 :         ns = p->se.sum_exec_runtime;
    4518          49 :         task_rq_unlock(rq, p, &rf);
    4519             : 
    4520          49 :         return ns;
    4521             : }
    4522             : 
    4523             : /*
    4524             :  * This function gets called by the timer code, with HZ frequency.
    4525             :  * We call it with interrupts disabled.
    4526             :  */
    4527       24506 : void scheduler_tick(void)
    4528             : {
    4529       24506 :         int cpu = smp_processor_id();
    4530       24506 :         struct rq *rq = cpu_rq(cpu);
    4531       24506 :         struct task_struct *curr = rq->curr;
    4532       24506 :         struct rq_flags rf;
    4533       24506 :         unsigned long thermal_pressure;
    4534             : 
    4535       24506 :         arch_scale_freq_tick();
    4536       24192 :         sched_clock_tick();
    4537             : 
    4538       24363 :         rq_lock(rq, &rf);
    4539             : 
    4540       24691 :         update_rq_clock(rq);
    4541       25079 :         thermal_pressure = arch_scale_thermal_pressure(cpu_of(rq));
    4542       25079 :         update_thermal_load_avg(rq_clock_thermal(rq), rq, thermal_pressure);
    4543       25197 :         curr->sched_class->task_tick(rq, curr, 0);
    4544       24910 :         calc_global_load_tick(rq);
    4545       24877 :         psi_task_tick(rq);
    4546             : 
    4547       24877 :         rq_unlock(rq, &rf);
    4548             : 
    4549       25344 :         perf_event_task_tick();
    4550             : 
    4551             : #ifdef CONFIG_SMP
    4552       25087 :         rq->idle_balance = idle_cpu(cpu);
    4553       25087 :         trigger_load_balance(rq);
    4554             : #endif
    4555       24998 : }
    4556             : 
    4557             : #ifdef CONFIG_NO_HZ_FULL
    4558             : 
    4559             : struct tick_work {
    4560             :         int                     cpu;
    4561             :         atomic_t                state;
    4562             :         struct delayed_work     work;
    4563             : };
    4564             : /* Values for ->state, see diagram below. */
    4565             : #define TICK_SCHED_REMOTE_OFFLINE       0
    4566             : #define TICK_SCHED_REMOTE_OFFLINING     1
    4567             : #define TICK_SCHED_REMOTE_RUNNING       2
    4568             : 
    4569             : /*
    4570             :  * State diagram for ->state:
    4571             :  *
    4572             :  *
    4573             :  *          TICK_SCHED_REMOTE_OFFLINE
    4574             :  *                    |   ^
    4575             :  *                    |   |
    4576             :  *                    |   | sched_tick_remote()
    4577             :  *                    |   |
    4578             :  *                    |   |
    4579             :  *                    +--TICK_SCHED_REMOTE_OFFLINING
    4580             :  *                    |   ^
    4581             :  *                    |   |
    4582             :  * sched_tick_start() |   | sched_tick_stop()
    4583             :  *                    |   |
    4584             :  *                    V   |
    4585             :  *          TICK_SCHED_REMOTE_RUNNING
    4586             :  *
    4587             :  *
    4588             :  * Other transitions get WARN_ON_ONCE(), except that sched_tick_remote()
    4589             :  * and sched_tick_start() are happy to leave the state in RUNNING.
    4590             :  */
    4591             : 
    4592             : static struct tick_work __percpu *tick_work_cpu;
    4593             : 
    4594             : static void sched_tick_remote(struct work_struct *work)
    4595             : {
    4596             :         struct delayed_work *dwork = to_delayed_work(work);
    4597             :         struct tick_work *twork = container_of(dwork, struct tick_work, work);
    4598             :         int cpu = twork->cpu;
    4599             :         struct rq *rq = cpu_rq(cpu);
    4600             :         struct task_struct *curr;
    4601             :         struct rq_flags rf;
    4602             :         u64 delta;
    4603             :         int os;
    4604             : 
    4605             :         /*
    4606             :          * Handle the tick only if it appears the remote CPU is running in full
    4607             :          * dynticks mode. The check is racy by nature, but missing a tick or
    4608             :          * having one too much is no big deal because the scheduler tick updates
    4609             :          * statistics and checks timeslices in a time-independent way, regardless
    4610             :          * of when exactly it is running.
    4611             :          */
    4612             :         if (!tick_nohz_tick_stopped_cpu(cpu))
    4613             :                 goto out_requeue;
    4614             : 
    4615             :         rq_lock_irq(rq, &rf);
    4616             :         curr = rq->curr;
    4617             :         if (cpu_is_offline(cpu))
    4618             :                 goto out_unlock;
    4619             : 
    4620             :         update_rq_clock(rq);
    4621             : 
    4622             :         if (!is_idle_task(curr)) {
    4623             :                 /*
    4624             :                  * Make sure the next tick runs within a reasonable
    4625             :                  * amount of time.
    4626             :                  */
    4627             :                 delta = rq_clock_task(rq) - curr->se.exec_start;
    4628             :                 WARN_ON_ONCE(delta > (u64)NSEC_PER_SEC * 3);
    4629             :         }
    4630             :         curr->sched_class->task_tick(rq, curr, 0);
    4631             : 
    4632             :         calc_load_nohz_remote(rq);
    4633             : out_unlock:
    4634             :         rq_unlock_irq(rq, &rf);
    4635             : out_requeue:
    4636             : 
    4637             :         /*
    4638             :          * Run the remote tick once per second (1Hz). This arbitrary
    4639             :          * frequency is large enough to avoid overload but short enough
    4640             :          * to keep scheduler internal stats reasonably up to date.  But
    4641             :          * first update state to reflect hotplug activity if required.
    4642             :          */
    4643             :         os = atomic_fetch_add_unless(&twork->state, -1, TICK_SCHED_REMOTE_RUNNING);
    4644             :         WARN_ON_ONCE(os == TICK_SCHED_REMOTE_OFFLINE);
    4645             :         if (os == TICK_SCHED_REMOTE_RUNNING)
    4646             :                 queue_delayed_work(system_unbound_wq, dwork, HZ);
    4647             : }
    4648             : 
    4649             : static void sched_tick_start(int cpu)
    4650             : {
    4651             :         int os;
    4652             :         struct tick_work *twork;
    4653             : 
    4654             :         if (housekeeping_cpu(cpu, HK_FLAG_TICK))
    4655             :                 return;
    4656             : 
    4657             :         WARN_ON_ONCE(!tick_work_cpu);
    4658             : 
    4659             :         twork = per_cpu_ptr(tick_work_cpu, cpu);
    4660             :         os = atomic_xchg(&twork->state, TICK_SCHED_REMOTE_RUNNING);
    4661             :         WARN_ON_ONCE(os == TICK_SCHED_REMOTE_RUNNING);
    4662             :         if (os == TICK_SCHED_REMOTE_OFFLINE) {
    4663             :                 twork->cpu = cpu;
    4664             :                 INIT_DELAYED_WORK(&twork->work, sched_tick_remote);
    4665             :                 queue_delayed_work(system_unbound_wq, &twork->work, HZ);
    4666             :         }
    4667             : }
    4668             : 
    4669             : #ifdef CONFIG_HOTPLUG_CPU
    4670             : static void sched_tick_stop(int cpu)
    4671             : {
    4672             :         struct tick_work *twork;
    4673             :         int os;
    4674             : 
    4675             :         if (housekeeping_cpu(cpu, HK_FLAG_TICK))
    4676             :                 return;
    4677             : 
    4678             :         WARN_ON_ONCE(!tick_work_cpu);
    4679             : 
    4680             :         twork = per_cpu_ptr(tick_work_cpu, cpu);
    4681             :         /* There cannot be competing actions, but don't rely on stop-machine. */
    4682             :         os = atomic_xchg(&twork->state, TICK_SCHED_REMOTE_OFFLINING);
    4683             :         WARN_ON_ONCE(os != TICK_SCHED_REMOTE_RUNNING);
    4684             :         /* Don't cancel, as this would mess up the state machine. */
    4685             : }
    4686             : #endif /* CONFIG_HOTPLUG_CPU */
    4687             : 
    4688             : int __init sched_tick_offload_init(void)
    4689             : {
    4690             :         tick_work_cpu = alloc_percpu(struct tick_work);
    4691             :         BUG_ON(!tick_work_cpu);
    4692             :         return 0;
    4693             : }
    4694             : 
    4695             : #else /* !CONFIG_NO_HZ_FULL */
    4696           4 : static inline void sched_tick_start(int cpu) { }
    4697           0 : static inline void sched_tick_stop(int cpu) { }
    4698             : #endif
    4699             : 
    4700             : #if defined(CONFIG_PREEMPTION) && (defined(CONFIG_DEBUG_PREEMPT) || \
    4701             :                                 defined(CONFIG_TRACE_PREEMPT_TOGGLE))
    4702             : /*
    4703             :  * If the value passed in is equal to the current preempt count
    4704             :  * then we just disabled preemption. Start timing the latency.
    4705             :  */
    4706             : static inline void preempt_latency_start(int val)
    4707             : {
    4708             :         if (preempt_count() == val) {
    4709             :                 unsigned long ip = get_lock_parent_ip();
    4710             : #ifdef CONFIG_DEBUG_PREEMPT
    4711             :                 current->preempt_disable_ip = ip;
    4712             : #endif
    4713             :                 trace_preempt_off(CALLER_ADDR0, ip);
    4714             :         }
    4715             : }
    4716             : 
    4717             : void preempt_count_add(int val)
    4718             : {
    4719             : #ifdef CONFIG_DEBUG_PREEMPT
    4720             :         /*
    4721             :          * Underflow?
    4722             :          */
    4723             :         if (DEBUG_LOCKS_WARN_ON((preempt_count() < 0)))
    4724             :                 return;
    4725             : #endif
    4726             :         __preempt_count_add(val);
    4727             : #ifdef CONFIG_DEBUG_PREEMPT
    4728             :         /*
    4729             :          * Spinlock count overflowing soon?
    4730             :          */
    4731             :         DEBUG_LOCKS_WARN_ON((preempt_count() & PREEMPT_MASK) >=
    4732             :                                 PREEMPT_MASK - 10);
    4733             : #endif
    4734             :         preempt_latency_start(val);
    4735             : }
    4736             : EXPORT_SYMBOL(preempt_count_add);
    4737             : NOKPROBE_SYMBOL(preempt_count_add);
    4738             : 
    4739             : /*
    4740             :  * If the value passed in equals to the current preempt count
    4741             :  * then we just enabled preemption. Stop timing the latency.
    4742             :  */
    4743             : static inline void preempt_latency_stop(int val)
    4744             : {
    4745             :         if (preempt_count() == val)
    4746             :                 trace_preempt_on(CALLER_ADDR0, get_lock_parent_ip());
    4747             : }
    4748             : 
    4749             : void preempt_count_sub(int val)
    4750             : {
    4751             : #ifdef CONFIG_DEBUG_PREEMPT
    4752             :         /*
    4753             :          * Underflow?
    4754             :          */
    4755             :         if (DEBUG_LOCKS_WARN_ON(val > preempt_count()))
    4756             :                 return;
    4757             :         /*
    4758             :          * Is the spinlock portion underflowing?
    4759             :          */
    4760             :         if (DEBUG_LOCKS_WARN_ON((val < PREEMPT_MASK) &&
    4761             :                         !(preempt_count() & PREEMPT_MASK)))
    4762             :                 return;
    4763             : #endif
    4764             : 
    4765             :         preempt_latency_stop(val);
    4766             :         __preempt_count_sub(val);
    4767             : }
    4768             : EXPORT_SYMBOL(preempt_count_sub);
    4769             : NOKPROBE_SYMBOL(preempt_count_sub);
    4770             : 
    4771             : #else
    4772        2543 : static inline void preempt_latency_start(int val) { }
    4773        2543 : static inline void preempt_latency_stop(int val) { }
    4774             : #endif
    4775             : 
    4776           0 : static inline unsigned long get_preempt_disable_ip(struct task_struct *p)
    4777             : {
    4778             : #ifdef CONFIG_DEBUG_PREEMPT
    4779             :         return p->preempt_disable_ip;
    4780             : #else
    4781           0 :         return 0;
    4782             : #endif
    4783             : }
    4784             : 
    4785             : /*
    4786             :  * Print scheduling while atomic bug:
    4787             :  */
    4788           0 : static noinline void __schedule_bug(struct task_struct *prev)
    4789             : {
    4790             :         /* Save this before calling printk(), since that will clobber it */
    4791           0 :         unsigned long preempt_disable_ip = get_preempt_disable_ip(current);
    4792             : 
    4793           0 :         if (oops_in_progress)
    4794             :                 return;
    4795             : 
    4796           0 :         printk(KERN_ERR "BUG: scheduling while atomic: %s/%d/0x%08x\n",
    4797           0 :                 prev->comm, prev->pid, preempt_count());
    4798             : 
    4799           0 :         debug_show_held_locks(prev);
    4800           0 :         print_modules();
    4801           0 :         if (irqs_disabled())
    4802           0 :                 print_irqtrace_events(prev);
    4803           0 :         if (IS_ENABLED(CONFIG_DEBUG_PREEMPT)
    4804             :             && in_atomic_preempt_off()) {
    4805             :                 pr_err("Preemption disabled at:");
    4806             :                 print_ip_sym(KERN_ERR, preempt_disable_ip);
    4807             :         }
    4808           0 :         if (panic_on_warn)
    4809           0 :                 panic("scheduling while atomic\n");
    4810             : 
    4811           0 :         dump_stack();
    4812           0 :         add_taint(TAINT_WARN, LOCKDEP_STILL_OK);
    4813             : }
    4814             : 
    4815             : /*
    4816             :  * Various schedule()-time debugging checks and statistics:
    4817             :  */
    4818       27963 : static inline void schedule_debug(struct task_struct *prev, bool preempt)
    4819             : {
    4820             : #ifdef CONFIG_SCHED_STACK_END_CHECK
    4821             :         if (task_stack_end_corrupted(prev))
    4822             :                 panic("corrupted stack end detected inside scheduler\n");
    4823             : 
    4824             :         if (task_scs_end_corrupted(prev))
    4825             :                 panic("corrupted shadow stack detected inside scheduler\n");
    4826             : #endif
    4827             : 
    4828             : #ifdef CONFIG_DEBUG_ATOMIC_SLEEP
    4829       27963 :         if (!preempt && prev->state && prev->non_block_count) {
    4830           0 :                 printk(KERN_ERR "BUG: scheduling in a non-blocking section: %s/%d/%i\n",
    4831           0 :                         prev->comm, prev->pid, prev->non_block_count);
    4832           0 :                 dump_stack();
    4833           0 :                 add_taint(TAINT_WARN, LOCKDEP_STILL_OK);
    4834             :         }
    4835             : #endif
    4836             : 
    4837       27963 :         if (unlikely(in_atomic_preempt_off())) {
    4838           0 :                 __schedule_bug(prev);
    4839           0 :                 preempt_count_set(PREEMPT_DISABLED);
    4840             :         }
    4841       83897 :         rcu_sleep_check();
    4842       27966 :         SCHED_WARN_ON(ct_state() == CONTEXT_USER);
    4843             : 
    4844       27966 :         profile_hit(SCHED_PROFILING, __builtin_return_address(0));
    4845             : 
    4846       27967 :         schedstat_inc(this_rq()->sched_count);
    4847       27967 : }
    4848             : 
    4849          79 : static void put_prev_task_balance(struct rq *rq, struct task_struct *prev,
    4850             :                                   struct rq_flags *rf)
    4851             : {
    4852             : #ifdef CONFIG_SMP
    4853          79 :         const struct sched_class *class;
    4854             :         /*
    4855             :          * We must do the balancing pass before put_prev_task(), such
    4856             :          * that when we release the rq->lock the task is in the same
    4857             :          * state as before we took rq->lock.
    4858             :          *
    4859             :          * We can terminate the balance pass as soon as we know there is
    4860             :          * a runnable task of @class priority or higher.
    4861             :          */
    4862         204 :         for_class_range(class, prev->sched_class, &idle_sched_class) {
    4863         193 :                 if (class->balance(rq, prev, rf))
    4864             :                         break;
    4865             :         }
    4866             : #endif
    4867             : 
    4868          78 :         put_prev_task(rq, prev);
    4869          78 : }
    4870             : 
    4871             : /*
    4872             :  * Pick up the highest-prio task:
    4873             :  */
    4874             : static inline struct task_struct *
    4875       27962 : pick_next_task(struct rq *rq, struct task_struct *prev, struct rq_flags *rf)
    4876             : {
    4877       27962 :         const struct sched_class *class;
    4878       27962 :         struct task_struct *p;
    4879             : 
    4880             :         /*
    4881             :          * Optimization: we know that if all tasks are in the fair class we can
    4882             :          * call that function directly, but only if the @prev task wasn't of a
    4883             :          * higher scheduling class, because otherwise those lose the
    4884             :          * opportunity to pull in more work from other CPUs.
    4885             :          */
    4886       27962 :         if (likely(prev->sched_class <= &fair_sched_class &&
    4887             :                    rq->nr_running == rq->cfs.h_nr_running)) {
    4888             : 
    4889       27883 :                 p = pick_next_task_fair(rq, prev, rf);
    4890       27884 :                 if (unlikely(p == RETRY_TASK))
    4891           0 :                         goto restart;
    4892             : 
    4893             :                 /* Assumes fair_sched_class->next == idle_sched_class */
    4894       27884 :                 if (!p) {
    4895        6926 :                         put_prev_task(rq, prev);
    4896        6927 :                         p = pick_next_task_idle(rq);
    4897             :                 }
    4898             : 
    4899       27884 :                 return p;
    4900             :         }
    4901             : 
    4902          79 : restart:
    4903          79 :         put_prev_task_balance(rq, prev, rf);
    4904             : 
    4905         281 :         for_each_class(class) {
    4906         202 :                 p = class->pick_next_task(rq);
    4907         203 :                 if (p)
    4908          79 :                         return p;
    4909             :         }
    4910             : 
    4911             :         /* The idle class should always have a runnable task: */
    4912           0 :         BUG();
    4913             : }
    4914             : 
    4915             : /*
    4916             :  * __schedule() is the main scheduler function.
    4917             :  *
    4918             :  * The main means of driving the scheduler and thus entering this function are:
    4919             :  *
    4920             :  *   1. Explicit blocking: mutex, semaphore, waitqueue, etc.
    4921             :  *
    4922             :  *   2. TIF_NEED_RESCHED flag is checked on interrupt and userspace return
    4923             :  *      paths. For example, see arch/x86/entry_64.S.
    4924             :  *
    4925             :  *      To drive preemption between tasks, the scheduler sets the flag in timer
    4926             :  *      interrupt handler scheduler_tick().
    4927             :  *
    4928             :  *   3. Wakeups don't really cause entry into schedule(). They add a
    4929             :  *      task to the run-queue and that's it.
    4930             :  *
    4931             :  *      Now, if the new task added to the run-queue preempts the current
    4932             :  *      task, then the wakeup sets TIF_NEED_RESCHED and schedule() gets
    4933             :  *      called on the nearest possible occasion:
    4934             :  *
    4935             :  *       - If the kernel is preemptible (CONFIG_PREEMPTION=y):
    4936             :  *
    4937             :  *         - in syscall or exception context, at the next outmost
    4938             :  *           preempt_enable(). (this might be as soon as the wake_up()'s
    4939             :  *           spin_unlock()!)
    4940             :  *
    4941             :  *         - in IRQ context, return from interrupt-handler to
    4942             :  *           preemptible context
    4943             :  *
    4944             :  *       - If the kernel is not preemptible (CONFIG_PREEMPTION is not set)
    4945             :  *         then at the next:
    4946             :  *
    4947             :  *          - cond_resched() call
    4948             :  *          - explicit schedule() call
    4949             :  *          - return from syscall or exception to user-space
    4950             :  *          - return from interrupt-handler to user-space
    4951             :  *
    4952             :  * WARNING: must be called with preemption disabled!
    4953             :  */
    4954       27961 : static void __sched notrace __schedule(bool preempt)
    4955             : {
    4956       27961 :         struct task_struct *prev, *next;
    4957       27961 :         unsigned long *switch_count;
    4958       27961 :         unsigned long prev_state;
    4959       27961 :         struct rq_flags rf;
    4960       27961 :         struct rq *rq;
    4961       27961 :         int cpu;
    4962             : 
    4963       27961 :         cpu = smp_processor_id();
    4964       27961 :         rq = cpu_rq(cpu);
    4965       27961 :         prev = rq->curr;
    4966             : 
    4967       27961 :         schedule_debug(prev, preempt);
    4968             : 
    4969       27967 :         if (sched_feat(HRTICK) || sched_feat(HRTICK_DL))
    4970             :                 hrtick_clear(rq);
    4971             : 
    4972       27967 :         local_irq_disable();
    4973       27967 :         rcu_note_context_switch(preempt);
    4974             : 
    4975             :         /*
    4976             :          * Make sure that signal_pending_state()->signal_pending() below
    4977             :          * can't be reordered with __set_current_state(TASK_INTERRUPTIBLE)
    4978             :          * done by the caller to avoid the race with signal_wake_up():
    4979             :          *
    4980             :          * __set_current_state(@state)          signal_wake_up()
    4981             :          * schedule()                             set_tsk_thread_flag(p, TIF_SIGPENDING)
    4982             :          *                                        wake_up_state(p, state)
    4983             :          *   LOCK rq->lock                       LOCK p->pi_state
    4984             :          *   smp_mb__after_spinlock()               smp_mb__after_spinlock()
    4985             :          *     if (signal_pending_state())          if (p->state & @state)
    4986             :          *
    4987             :          * Also, the membarrier system call requires a full memory barrier
    4988             :          * after coming from user-space, before storing to rq->curr.
    4989             :          */
    4990       27964 :         rq_lock(rq, &rf);
    4991       27965 :         smp_mb__after_spinlock();
    4992             : 
    4993             :         /* Promote REQ to ACT */
    4994       27965 :         rq->clock_update_flags <<= 1;
    4995       27965 :         update_rq_clock(rq);
    4996             : 
    4997       27963 :         switch_count = &prev->nivcsw;
    4998             : 
    4999             :         /*
    5000             :          * We must load prev->state once (task_struct::state is volatile), such
    5001             :          * that:
    5002             :          *
    5003             :          *  - we form a control dependency vs deactivate_task() below.
    5004             :          *  - ptrace_{,un}freeze_traced() can change ->state underneath us.
    5005             :          */
    5006       27963 :         prev_state = prev->state;
    5007       27963 :         if (!preempt && prev_state) {
    5008       14838 :                 if (signal_pending_state(prev_state, prev)) {
    5009           0 :                         prev->state = TASK_RUNNING;
    5010             :                 } else {
    5011       29676 :                         prev->sched_contributes_to_load =
    5012       14838 :                                 (prev_state & TASK_UNINTERRUPTIBLE) &&
    5013       14838 :                                 !(prev_state & TASK_NOLOAD) &&
    5014        2713 :                                 !(prev->flags & PF_FROZEN);
    5015             : 
    5016       14838 :                         if (prev->sched_contributes_to_load)
    5017        2713 :                                 rq->nr_uninterruptible++;
    5018             : 
    5019             :                         /*
    5020             :                          * __schedule()                 ttwu()
    5021             :                          *   prev_state = prev->state;    if (p->on_rq && ...)
    5022             :                          *   if (prev_state)                goto out;
    5023             :                          *     p->on_rq = 0;           smp_acquire__after_ctrl_dep();
    5024             :                          *                                p->state = TASK_WAKING
    5025             :                          *
    5026             :                          * Where __schedule() and ttwu() have matching control dependencies.
    5027             :                          *
    5028             :                          * After this, schedule() must not care about p->state any more.
    5029             :                          */
    5030       14838 :                         deactivate_task(rq, prev, DEQUEUE_SLEEP | DEQUEUE_NOCLOCK);
    5031             : 
    5032       14837 :                         if (prev->in_iowait) {
    5033        1873 :                                 atomic_inc(&rq->nr_iowait);
    5034        1873 :                                 delayacct_blkio_start();
    5035             :                         }
    5036             :                 }
    5037       14837 :                 switch_count = &prev->nvcsw;
    5038             :         }
    5039             : 
    5040       27962 :         next = pick_next_task(rq, prev, &rf);
    5041       27960 :         clear_tsk_need_resched(prev);
    5042       27967 :         clear_preempt_need_resched();
    5043             : 
    5044       27967 :         if (likely(prev != next)) {
    5045       26515 :                 rq->nr_switches++;
    5046             :                 /*
    5047             :                  * RCU users of rcu_dereference(rq->curr) may not see
    5048             :                  * changes to task_struct made by pick_next_task().
    5049             :                  */
    5050       26515 :                 RCU_INIT_POINTER(rq->curr, next);
    5051             :                 /*
    5052             :                  * The membarrier system call requires each architecture
    5053             :                  * to have a full memory barrier after updating
    5054             :                  * rq->curr, before returning to user-space.
    5055             :                  *
    5056             :                  * Here are the schemes providing that barrier on the
    5057             :                  * various architectures:
    5058             :                  * - mm ? switch_mm() : mmdrop() for x86, s390, sparc, PowerPC.
    5059             :                  *   switch_mm() rely on membarrier_arch_switch_mm() on PowerPC.
    5060             :                  * - finish_lock_switch() for weakly-ordered
    5061             :                  *   architectures where spin_unlock is a full barrier,
    5062             :                  * - switch_to() for arm64 (weakly-ordered, spin_unlock
    5063             :                  *   is a RELEASE barrier),
    5064             :                  */
    5065       26515 :                 ++*switch_count;
    5066             : 
    5067       26515 :                 migrate_disable_switch(rq, prev);
    5068       26512 :                 psi_sched_switch(prev, next, !task_on_rq_queued(prev));
    5069             : 
    5070       26512 :                 trace_sched_switch(preempt, prev, next);
    5071             : 
    5072             :                 /* Also unlocks the rq: */
    5073       52049 :                 rq = context_switch(rq, prev, next, &rf);
    5074             :         } else {
    5075        1452 :                 rq->clock_update_flags &= ~(RQCF_ACT_SKIP|RQCF_REQ_SKIP);
    5076             : 
    5077        1452 :                 rq_unpin_lock(rq, &rf);
    5078        1452 :                 __balance_callbacks(rq);
    5079        1452 :                 raw_spin_unlock_irq(&rq->lock);
    5080             :         }
    5081       26990 : }
    5082             : 
    5083         900 : void __noreturn do_task_dead(void)
    5084             : {
    5085             :         /* Causes final put_task_struct in finish_task_switch(): */
    5086         900 :         set_special_state(TASK_DEAD);
    5087             : 
    5088             :         /* Tell freezer to ignore us: */
    5089         900 :         current->flags |= PF_NOFREEZE;
    5090             : 
    5091         900 :         __schedule(false);
    5092           0 :         BUG();
    5093             : 
    5094             :         /* Avoid "noreturn function does return" - but don't continue if BUG() is a NOP: */
    5095             :         for (;;)
    5096             :                 cpu_relax();
    5097             : }
    5098             : 
    5099       17578 : static inline void sched_submit_work(struct task_struct *tsk)
    5100             : {
    5101       17578 :         unsigned int task_flags;
    5102             : 
    5103       17578 :         if (!tsk->state)
    5104             :                 return;
    5105             : 
    5106       13944 :         task_flags = tsk->flags;
    5107             :         /*
    5108             :          * If a worker went to sleep, notify and ask workqueue whether
    5109             :          * it wants to wake up a task to maintain concurrency.
    5110             :          * As this function is called inside the schedule() context,
    5111             :          * we disable preemption to avoid it calling schedule() again
    5112             :          * in the possible wakeup of a kworker and because wq_worker_sleeping()
    5113             :          * requires it.
    5114             :          */
    5115       13944 :         if (task_flags & (PF_WQ_WORKER | PF_IO_WORKER)) {
    5116        1908 :                 preempt_disable();
    5117        1908 :                 if (task_flags & PF_WQ_WORKER)
    5118        1908 :                         wq_worker_sleeping(tsk);
    5119             :                 else
    5120        1908 :                         io_wq_worker_sleeping(tsk);
    5121        1908 :                 preempt_enable_no_resched();
    5122             :         }
    5123             : 
    5124       13944 :         if (tsk_is_pi_blocked(tsk))
    5125             :                 return;
    5126             : 
    5127             :         /*
    5128             :          * If we are going to sleep and we have plugged IO queued,
    5129             :          * make sure to submit it to avoid deadlocks.
    5130             :          */
    5131       13958 :         if (blk_needs_flush_plug(tsk))
    5132           0 :                 blk_schedule_flush_plug(tsk);
    5133             : }
    5134             : 
    5135       17498 : static void sched_update_worker(struct task_struct *tsk)
    5136             : {
    5137       17498 :         if (tsk->flags & (PF_WQ_WORKER | PF_IO_WORKER)) {
    5138        1879 :                 if (tsk->flags & PF_WQ_WORKER)
    5139        1879 :                         wq_worker_running(tsk);
    5140             :                 else
    5141       17499 :                         io_wq_worker_running(tsk);
    5142             :         }
    5143       17499 : }
    5144             : 
    5145       17578 : asmlinkage __visible void __sched schedule(void)
    5146             : {
    5147       17578 :         struct task_struct *tsk = current;
    5148             : 
    5149       17578 :         sched_submit_work(tsk);
    5150       17590 :         do {
    5151       17590 :                 preempt_disable();
    5152       17590 :                 __schedule(false);
    5153       17510 :                 sched_preempt_enable_no_resched();
    5154       17510 :         } while (need_resched());
    5155       17499 :         sched_update_worker(tsk);
    5156       17498 : }
    5157             : EXPORT_SYMBOL(schedule);
    5158             : 
    5159             : /*
    5160             :  * synchronize_rcu_tasks() makes sure that no task is stuck in preempted
    5161             :  * state (have scheduled out non-voluntarily) by making sure that all
    5162             :  * tasks have either left the run queue or have gone into user space.
    5163             :  * As idle tasks do not do either, they must not ever be preempted
    5164             :  * (schedule out non-voluntarily).
    5165             :  *
    5166             :  * schedule_idle() is similar to schedule_preempt_disable() except that it
    5167             :  * never enables preemption because it does not call sched_submit_work().
    5168             :  */
    5169        6839 : void __sched schedule_idle(void)
    5170             : {
    5171             :         /*
    5172             :          * As this skips calling sched_submit_work(), which the idle task does
    5173             :          * regardless because that function is a nop when the task is in a
    5174             :          * TASK_RUNNING state, make sure this isn't used someplace that the
    5175             :          * current task can be in any other state. Note, idle is always in the
    5176             :          * TASK_RUNNING state.
    5177             :          */
    5178        6839 :         WARN_ON_ONCE(current->state);
    5179        6932 :         do {
    5180        6932 :                 __schedule(false);
    5181        6933 :         } while (need_resched());
    5182        6840 : }
    5183             : 
    5184             : #if defined(CONFIG_CONTEXT_TRACKING) && !defined(CONFIG_HAVE_CONTEXT_TRACKING_OFFSTACK)
    5185             : asmlinkage __visible void __sched schedule_user(void)
    5186             : {
    5187             :         /*
    5188             :          * If we come here after a random call to set_need_resched(),
    5189             :          * or we have been woken up remotely but the IPI has not yet arrived,
    5190             :          * we haven't yet exited the RCU idle mode. Do it here manually until
    5191             :          * we find a better solution.
    5192             :          *
    5193             :          * NB: There are buggy callers of this function.  Ideally we
    5194             :          * should warn if prev_state != CONTEXT_USER, but that will trigger
    5195             :          * too frequently to make sense yet.
    5196             :          */
    5197             :         enum ctx_state prev_state = exception_enter();
    5198             :         schedule();
    5199             :         exception_exit(prev_state);
    5200             : }
    5201             : #endif
    5202             : 
    5203             : /**
    5204             :  * schedule_preempt_disabled - called with preemption disabled
    5205             :  *
    5206             :  * Returns with preemption disabled. Note: preempt_count must be 1
    5207             :  */
    5208          94 : void __sched schedule_preempt_disabled(void)
    5209             : {
    5210          94 :         sched_preempt_enable_no_resched();
    5211          94 :         schedule();
    5212          94 :         preempt_disable();
    5213          94 : }
    5214             : 
    5215        2537 : static void __sched notrace preempt_schedule_common(void)
    5216             : {
    5217        2543 :         do {
    5218             :                 /*
    5219             :                  * Because the function tracer can trace preempt_count_sub()
    5220             :                  * and it also uses preempt_enable/disable_notrace(), if
    5221             :                  * NEED_RESCHED is set, the preempt_enable_notrace() called
    5222             :                  * by the function tracer will call this function again and
    5223             :                  * cause infinite recursion.
    5224             :                  *
    5225             :                  * Preemption must be disabled here before the function
    5226             :                  * tracer can trace. Break up preempt_disable() into two
    5227             :                  * calls. One to disable preemption without fear of being
    5228             :                  * traced. The other to still record the preemption latency,
    5229             :                  * which can also be traced by the function tracer.
    5230             :                  */
    5231        2543 :                 preempt_disable_notrace();
    5232        2543 :                 preempt_latency_start(1);
    5233        2543 :                 __schedule(true);
    5234        2543 :                 preempt_latency_stop(1);
    5235        2543 :                 preempt_enable_no_resched_notrace();
    5236             : 
    5237             :                 /*
    5238             :                  * Check again in case we missed a preemption opportunity
    5239             :                  * between schedule and now.
    5240             :                  */
    5241        2543 :         } while (need_resched());
    5242        2537 : }
    5243             : 
    5244             : #ifdef CONFIG_PREEMPTION
    5245             : /*
    5246             :  * This is the entry point to schedule() from in-kernel preemption
    5247             :  * off of preempt_enable.
    5248             :  */
    5249             : asmlinkage __visible void __sched notrace preempt_schedule(void)
    5250             : {
    5251             :         /*
    5252             :          * If there is a non-zero preempt_count or interrupts are disabled,
    5253             :          * we do not want to preempt the current task. Just return..
    5254             :          */
    5255             :         if (likely(!preemptible()))
    5256             :                 return;
    5257             : 
    5258             :         preempt_schedule_common();
    5259             : }
    5260             : NOKPROBE_SYMBOL(preempt_schedule);
    5261             : EXPORT_SYMBOL(preempt_schedule);
    5262             : 
    5263             : #ifdef CONFIG_PREEMPT_DYNAMIC
    5264             : DEFINE_STATIC_CALL(preempt_schedule, __preempt_schedule_func);
    5265             : EXPORT_STATIC_CALL_TRAMP(preempt_schedule);
    5266             : #endif
    5267             : 
    5268             : 
    5269             : /**
    5270             :  * preempt_schedule_notrace - preempt_schedule called by tracing
    5271             :  *
    5272             :  * The tracing infrastructure uses preempt_enable_notrace to prevent
    5273             :  * recursion and tracing preempt enabling caused by the tracing
    5274             :  * infrastructure itself. But as tracing can happen in areas coming
    5275             :  * from userspace or just about to enter userspace, a preempt enable
    5276             :  * can occur before user_exit() is called. This will cause the scheduler
    5277             :  * to be called when the system is still in usermode.
    5278             :  *
    5279             :  * To prevent this, the preempt_enable_notrace will use this function
    5280             :  * instead of preempt_schedule() to exit user context if needed before
    5281             :  * calling the scheduler.
    5282             :  */
    5283             : asmlinkage __visible void __sched notrace preempt_schedule_notrace(void)
    5284             : {
    5285             :         enum ctx_state prev_ctx;
    5286             : 
    5287             :         if (likely(!preemptible()))
    5288             :                 return;
    5289             : 
    5290             :         do {
    5291             :                 /*
    5292             :                  * Because the function tracer can trace preempt_count_sub()
    5293             :                  * and it also uses preempt_enable/disable_notrace(), if
    5294             :                  * NEED_RESCHED is set, the preempt_enable_notrace() called
    5295             :                  * by the function tracer will call this function again and
    5296             :                  * cause infinite recursion.
    5297             :                  *
    5298             :                  * Preemption must be disabled here before the function
    5299             :                  * tracer can trace. Break up preempt_disable() into two
    5300             :                  * calls. One to disable preemption without fear of being
    5301             :                  * traced. The other to still record the preemption latency,
    5302             :                  * which can also be traced by the function tracer.
    5303             :                  */
    5304             :                 preempt_disable_notrace();
    5305             :                 preempt_latency_start(1);
    5306             :                 /*
    5307             :                  * Needs preempt disabled in case user_exit() is traced
    5308             :                  * and the tracer calls preempt_enable_notrace() causing
    5309             :                  * an infinite recursion.
    5310             :                  */
    5311             :                 prev_ctx = exception_enter();
    5312             :                 __schedule(true);
    5313             :                 exception_exit(prev_ctx);
    5314             : 
    5315             :                 preempt_latency_stop(1);
    5316             :                 preempt_enable_no_resched_notrace();
    5317             :         } while (need_resched());
    5318             : }
    5319             : EXPORT_SYMBOL_GPL(preempt_schedule_notrace);
    5320             : 
    5321             : #ifdef CONFIG_PREEMPT_DYNAMIC
    5322             : DEFINE_STATIC_CALL(preempt_schedule_notrace, __preempt_schedule_notrace_func);
    5323             : EXPORT_STATIC_CALL_TRAMP(preempt_schedule_notrace);
    5324             : #endif
    5325             : 
    5326             : #endif /* CONFIG_PREEMPTION */
    5327             : 
    5328             : #ifdef CONFIG_PREEMPT_DYNAMIC
    5329             : 
    5330             : #include <linux/entry-common.h>
    5331             : 
    5332             : /*
    5333             :  * SC:cond_resched
    5334             :  * SC:might_resched
    5335             :  * SC:preempt_schedule
    5336             :  * SC:preempt_schedule_notrace
    5337             :  * SC:irqentry_exit_cond_resched
    5338             :  *
    5339             :  *
    5340             :  * NONE:
    5341             :  *   cond_resched               <- __cond_resched
    5342             :  *   might_resched              <- RET0
    5343             :  *   preempt_schedule           <- NOP
    5344             :  *   preempt_schedule_notrace   <- NOP
    5345             :  *   irqentry_exit_cond_resched <- NOP
    5346             :  *
    5347             :  * VOLUNTARY:
    5348             :  *   cond_resched               <- __cond_resched
    5349             :  *   might_resched              <- __cond_resched
    5350             :  *   preempt_schedule           <- NOP
    5351             :  *   preempt_schedule_notrace   <- NOP
    5352             :  *   irqentry_exit_cond_resched <- NOP
    5353             :  *
    5354             :  * FULL:
    5355             :  *   cond_resched               <- RET0
    5356             :  *   might_resched              <- RET0
    5357             :  *   preempt_schedule           <- preempt_schedule
    5358             :  *   preempt_schedule_notrace   <- preempt_schedule_notrace
    5359             :  *   irqentry_exit_cond_resched <- irqentry_exit_cond_resched
    5360             :  */
    5361             : 
    5362             : enum {
    5363             :         preempt_dynamic_none = 0,
    5364             :         preempt_dynamic_voluntary,
    5365             :         preempt_dynamic_full,
    5366             : };
    5367             : 
    5368             : static int preempt_dynamic_mode = preempt_dynamic_full;
    5369             : 
    5370             : static int sched_dynamic_mode(const char *str)
    5371             : {
    5372             :         if (!strcmp(str, "none"))
    5373             :                 return 0;
    5374             : 
    5375             :         if (!strcmp(str, "voluntary"))
    5376             :                 return 1;
    5377             : 
    5378             :         if (!strcmp(str, "full"))
    5379             :                 return 2;
    5380             : 
    5381             :         return -1;
    5382             : }
    5383             : 
    5384             : static void sched_dynamic_update(int mode)
    5385             : {
    5386             :         /*
    5387             :          * Avoid {NONE,VOLUNTARY} -> FULL transitions from ever ending up in
    5388             :          * the ZERO state, which is invalid.
    5389             :          */
    5390             :         static_call_update(cond_resched, __cond_resched);
    5391             :         static_call_update(might_resched, __cond_resched);
    5392             :         static_call_update(preempt_schedule, __preempt_schedule_func);
    5393             :         static_call_update(preempt_schedule_notrace, __preempt_schedule_notrace_func);
    5394             :         static_call_update(irqentry_exit_cond_resched, irqentry_exit_cond_resched);
    5395             : 
    5396             :         switch (mode) {
    5397             :         case preempt_dynamic_none:
    5398             :                 static_call_update(cond_resched, __cond_resched);
    5399             :                 static_call_update(might_resched, (typeof(&__cond_resched)) __static_call_return0);
    5400             :                 static_call_update(preempt_schedule, (typeof(&preempt_schedule)) NULL);
    5401             :                 static_call_update(preempt_schedule_notrace, (typeof(&preempt_schedule_notrace)) NULL);
    5402             :                 static_call_update(irqentry_exit_cond_resched, (typeof(&irqentry_exit_cond_resched)) NULL);
    5403             :                 pr_info("Dynamic Preempt: none\n");
    5404             :                 break;
    5405             : 
    5406             :         case preempt_dynamic_voluntary:
    5407             :                 static_call_update(cond_resched, __cond_resched);
    5408             :                 static_call_update(might_resched, __cond_resched);
    5409             :                 static_call_update(preempt_schedule, (typeof(&preempt_schedule)) NULL);
    5410             :                 static_call_update(preempt_schedule_notrace, (typeof(&preempt_schedule_notrace)) NULL);
    5411             :                 static_call_update(irqentry_exit_cond_resched, (typeof(&irqentry_exit_cond_resched)) NULL);
    5412             :                 pr_info("Dynamic Preempt: voluntary\n");
    5413             :                 break;
    5414             : 
    5415             :         case preempt_dynamic_full:
    5416             :                 static_call_update(cond_resched, (typeof(&__cond_resched)) __static_call_return0);
    5417             :                 static_call_update(might_resched, (typeof(&__cond_resched)) __static_call_return0);
    5418             :                 static_call_update(preempt_schedule, __preempt_schedule_func);
    5419             :                 static_call_update(preempt_schedule_notrace, __preempt_schedule_notrace_func);
    5420             :                 static_call_update(irqentry_exit_cond_resched, irqentry_exit_cond_resched);
    5421             :                 pr_info("Dynamic Preempt: full\n");
    5422             :                 break;
    5423             :         }
    5424             : 
    5425             :         preempt_dynamic_mode = mode;
    5426             : }
    5427             : 
    5428             : static int __init setup_preempt_mode(char *str)
    5429             : {
    5430             :         int mode = sched_dynamic_mode(str);
    5431             :         if (mode < 0) {
    5432             :                 pr_warn("Dynamic Preempt: unsupported mode: %s\n", str);
    5433             :                 return 1;
    5434             :         }
    5435             : 
    5436             :         sched_dynamic_update(mode);
    5437             :         return 0;
    5438             : }
    5439             : __setup("preempt=", setup_preempt_mode);
    5440             : 
    5441             : #ifdef CONFIG_SCHED_DEBUG
    5442             : 
    5443             : static ssize_t sched_dynamic_write(struct file *filp, const char __user *ubuf,
    5444             :                                    size_t cnt, loff_t *ppos)
    5445             : {
    5446             :         char buf[16];
    5447             :         int mode;
    5448             : 
    5449             :         if (cnt > 15)
    5450             :                 cnt = 15;
    5451             : 
    5452             :         if (copy_from_user(&buf, ubuf, cnt))
    5453             :                 return -EFAULT;
    5454             : 
    5455             :         buf[cnt] = 0;
    5456             :         mode = sched_dynamic_mode(strstrip(buf));
    5457             :         if (mode < 0)
    5458             :                 return mode;
    5459             : 
    5460             :         sched_dynamic_update(mode);
    5461             : 
    5462             :         *ppos += cnt;
    5463             : 
    5464             :         return cnt;
    5465             : }
    5466             : 
    5467             : static int sched_dynamic_show(struct seq_file *m, void *v)
    5468             : {
    5469             :         static const char * preempt_modes[] = {
    5470             :                 "none", "voluntary", "full"
    5471             :         };
    5472             :         int i;
    5473             : 
    5474             :         for (i = 0; i < ARRAY_SIZE(preempt_modes); i++) {
    5475             :                 if (preempt_dynamic_mode == i)
    5476             :                         seq_puts(m, "(");
    5477             :                 seq_puts(m, preempt_modes[i]);
    5478             :                 if (preempt_dynamic_mode == i)
    5479             :                         seq_puts(m, ")");
    5480             : 
    5481             :                 seq_puts(m, " ");
    5482             :         }
    5483             : 
    5484             :         seq_puts(m, "\n");
    5485             :         return 0;
    5486             : }
    5487             : 
    5488             : static int sched_dynamic_open(struct inode *inode, struct file *filp)
    5489             : {
    5490             :         return single_open(filp, sched_dynamic_show, NULL);
    5491             : }
    5492             : 
    5493             : static const struct file_operations sched_dynamic_fops = {
    5494             :         .open           = sched_dynamic_open,
    5495             :         .write          = sched_dynamic_write,
    5496             :         .read           = seq_read,
    5497             :         .llseek         = seq_lseek,
    5498             :         .release        = single_release,
    5499             : };
    5500             : 
    5501             : static __init int sched_init_debug_dynamic(void)
    5502             : {
    5503             :         debugfs_create_file("sched_preempt", 0644, NULL, NULL, &sched_dynamic_fops);
    5504             :         return 0;
    5505             : }
    5506             : late_initcall(sched_init_debug_dynamic);
    5507             : 
    5508             : #endif /* CONFIG_SCHED_DEBUG */
    5509             : #endif /* CONFIG_PREEMPT_DYNAMIC */
    5510             : 
    5511             : 
    5512             : /*
    5513             :  * This is the entry point to schedule() from kernel preemption
    5514             :  * off of irq context.
    5515             :  * Note, that this is called and return with irqs disabled. This will
    5516             :  * protect us against recursive calling from irq.
    5517             :  */
    5518           0 : asmlinkage __visible void __sched preempt_schedule_irq(void)
    5519             : {
    5520           0 :         enum ctx_state prev_state;
    5521             : 
    5522             :         /* Catch callers which need to be fixed */
    5523           0 :         BUG_ON(preempt_count() || !irqs_disabled());
    5524             : 
    5525           0 :         prev_state = exception_enter();
    5526             : 
    5527           0 :         do {
    5528           0 :                 preempt_disable();
    5529           0 :                 local_irq_enable();
    5530           0 :                 __schedule(true);
    5531           0 :                 local_irq_disable();
    5532           0 :                 sched_preempt_enable_no_resched();
    5533           0 :         } while (need_resched());
    5534             : 
    5535           0 :         exception_exit(prev_state);
    5536           0 : }
    5537             : 
    5538        4745 : int default_wake_function(wait_queue_entry_t *curr, unsigned mode, int wake_flags,
    5539             :                           void *key)
    5540             : {
    5541        4745 :         WARN_ON_ONCE(IS_ENABLED(CONFIG_SCHED_DEBUG) && wake_flags & ~WF_SYNC);
    5542        4745 :         return try_to_wake_up(curr->private, mode, wake_flags);
    5543             : }
    5544             : EXPORT_SYMBOL(default_wake_function);
    5545             : 
    5546             : #ifdef CONFIG_RT_MUTEXES
    5547             : 
    5548           8 : static inline int __rt_effective_prio(struct task_struct *pi_task, int prio)
    5549             : {
    5550           8 :         if (pi_task)
    5551           0 :                 prio = min(prio, pi_task->prio);
    5552             : 
    5553           8 :         return prio;
    5554             : }
    5555             : 
    5556           8 : static inline int rt_effective_prio(struct task_struct *p, int prio)
    5557             : {
    5558           8 :         struct task_struct *pi_task = rt_mutex_get_top_task(p);
    5559             : 
    5560           8 :         return __rt_effective_prio(pi_task, prio);
    5561             : }
    5562             : 
    5563             : /*
    5564             :  * rt_mutex_setprio - set the current priority of a task
    5565             :  * @p: task to boost
    5566             :  * @pi_task: donor task
    5567             :  *
    5568             :  * This function changes the 'effective' priority of a task. It does
    5569             :  * not touch ->normal_prio like __setscheduler().
    5570             :  *
    5571             :  * Used by the rt_mutex code to implement priority inheritance
    5572             :  * logic. Call site only calls if the priority of the task changed.
    5573             :  */
    5574           0 : void rt_mutex_setprio(struct task_struct *p, struct task_struct *pi_task)
    5575             : {
    5576           0 :         int prio, oldprio, queued, running, queue_flag =
    5577             :                 DEQUEUE_SAVE | DEQUEUE_MOVE | DEQUEUE_NOCLOCK;
    5578           0 :         const struct sched_class *prev_class;
    5579           0 :         struct rq_flags rf;
    5580           0 :         struct rq *rq;
    5581             : 
    5582             :         /* XXX used to be waiter->prio, not waiter->task->prio */
    5583           0 :         prio = __rt_effective_prio(pi_task, p->normal_prio);
    5584             : 
    5585             :         /*
    5586             :          * If nothing changed; bail early.
    5587             :          */
    5588           0 :         if (p->pi_top_task == pi_task && prio == p->prio && !dl_prio(prio))
    5589           0 :                 return;
    5590             : 
    5591           0 :         rq = __task_rq_lock(p, &rf);
    5592           0 :         update_rq_clock(rq);
    5593             :         /*
    5594             :          * Set under pi_lock && rq->lock, such that the value can be used under
    5595             :          * either lock.
    5596             :          *
    5597             :          * Note that there is loads of tricky to make this pointer cache work
    5598             :          * right. rt_mutex_slowunlock()+rt_mutex_postunlock() work together to
    5599             :          * ensure a task is de-boosted (pi_task is set to NULL) before the
    5600             :          * task is allowed to run again (and can exit). This ensures the pointer
    5601             :          * points to a blocked task -- which guarantees the task is present.
    5602             :          */
    5603           0 :         p->pi_top_task = pi_task;
    5604             : 
    5605             :         /*
    5606             :          * For FIFO/RR we only need to set prio, if that matches we're done.
    5607             :          */
    5608           0 :         if (prio == p->prio && !dl_prio(prio))
    5609           0 :                 goto out_unlock;
    5610             : 
    5611             :         /*
    5612             :          * Idle task boosting is a nono in general. There is one
    5613             :          * exception, when PREEMPT_RT and NOHZ is active:
    5614             :          *
    5615             :          * The idle task calls get_next_timer_interrupt() and holds
    5616             :          * the timer wheel base->lock on the CPU and another CPU wants
    5617             :          * to access the timer (probably to cancel it). We can safely
    5618             :          * ignore the boosting request, as the idle CPU runs this code
    5619             :          * with interrupts disabled and will complete the lock
    5620             :          * protected section without being interrupted. So there is no
    5621             :          * real need to boost.
    5622             :          */
    5623           0 :         if (unlikely(p == rq->idle)) {
    5624           0 :                 WARN_ON(p != rq->curr);
    5625           0 :                 WARN_ON(p->pi_blocked_on);
    5626           0 :                 goto out_unlock;
    5627             :         }
    5628             : 
    5629           0 :         trace_sched_pi_setprio(p, pi_task);
    5630           0 :         oldprio = p->prio;
    5631             : 
    5632           0 :         if (oldprio == prio)
    5633           0 :                 queue_flag &= ~DEQUEUE_MOVE;
    5634             : 
    5635           0 :         prev_class = p->sched_class;
    5636           0 :         queued = task_on_rq_queued(p);
    5637           0 :         running = task_current(rq, p);
    5638           0 :         if (queued)
    5639           0 :                 dequeue_task(rq, p, queue_flag);
    5640           0 :         if (running)
    5641           0 :                 put_prev_task(rq, p);
    5642             : 
    5643             :         /*
    5644             :          * Boosting condition are:
    5645             :          * 1. -rt task is running and holds mutex A
    5646             :          *      --> -dl task blocks on mutex A
    5647             :          *
    5648             :          * 2. -dl task is running and holds mutex A
    5649             :          *      --> -dl task blocks on mutex A and could preempt the
    5650             :          *          running task
    5651             :          */
    5652           0 :         if (dl_prio(prio)) {
    5653           0 :                 if (!dl_prio(p->normal_prio) ||
    5654           0 :                     (pi_task && dl_prio(pi_task->prio) &&
    5655           0 :                      dl_entity_preempt(&pi_task->dl, &p->dl))) {
    5656           0 :                         p->dl.pi_se = pi_task->dl.pi_se;
    5657           0 :                         queue_flag |= ENQUEUE_REPLENISH;
    5658             :                 } else {
    5659           0 :                         p->dl.pi_se = &p->dl;
    5660             :                 }
    5661           0 :                 p->sched_class = &dl_sched_class;
    5662           0 :         } else if (rt_prio(prio)) {
    5663           0 :                 if (dl_prio(oldprio))
    5664           0 :                         p->dl.pi_se = &p->dl;
    5665           0 :                 if (oldprio < prio)
    5666           0 :                         queue_flag |= ENQUEUE_HEAD;
    5667           0 :                 p->sched_class = &rt_sched_class;
    5668             :         } else {
    5669           0 :                 if (dl_prio(oldprio))
    5670           0 :                         p->dl.pi_se = &p->dl;
    5671           0 :                 if (rt_prio(oldprio))
    5672           0 :                         p->rt.timeout = 0;
    5673           0 :                 p->sched_class = &fair_sched_class;
    5674             :         }
    5675             : 
    5676           0 :         p->prio = prio;
    5677             : 
    5678           0 :         if (queued)
    5679           0 :                 enqueue_task(rq, p, queue_flag);
    5680           0 :         if (running)
    5681           0 :                 set_next_task(rq, p);
    5682             : 
    5683           0 :         check_class_changed(rq, p, prev_class, oldprio);
    5684           0 : out_unlock:
    5685             :         /* Avoid rq from going away on us: */
    5686           0 :         preempt_disable();
    5687             : 
    5688           0 :         rq_unpin_lock(rq, &rf);
    5689           0 :         __balance_callbacks(rq);
    5690           0 :         raw_spin_unlock(&rq->lock);
    5691             : 
    5692           0 :         preempt_enable();
    5693             : }
    5694             : #else
    5695             : static inline int rt_effective_prio(struct task_struct *p, int prio)
    5696             : {
    5697             :         return prio;
    5698             : }
    5699             : #endif
    5700             : 
    5701          39 : void set_user_nice(struct task_struct *p, long nice)
    5702             : {
    5703          39 :         bool queued, running;
    5704          39 :         int old_prio;
    5705          39 :         struct rq_flags rf;
    5706          39 :         struct rq *rq;
    5707             : 
    5708          39 :         if (task_nice(p) == nice || nice < MIN_NICE || nice > MAX_NICE)
    5709          18 :                 return;
    5710             :         /*
    5711             :          * We have to be careful, if called from sys_setpriority(),
    5712             :          * the task might be in the middle of scheduling on another CPU.
    5713             :          */
    5714          21 :         rq = task_rq_lock(p, &rf);
    5715          21 :         update_rq_clock(rq);
    5716             : 
    5717             :         /*
    5718             :          * The RT priorities are set via sched_setscheduler(), but we still
    5719             :          * allow the 'normal' nice value to be set - but as expected
    5720             :          * it won't have any effect on scheduling until the task is
    5721             :          * SCHED_DEADLINE, SCHED_FIFO or SCHED_RR:
    5722             :          */
    5723          21 :         if (task_has_dl_policy(p) || task_has_rt_policy(p)) {
    5724           0 :                 p->static_prio = NICE_TO_PRIO(nice);
    5725           0 :                 goto out_unlock;
    5726             :         }
    5727          21 :         queued = task_on_rq_queued(p);
    5728          21 :         running = task_current(rq, p);
    5729          21 :         if (queued)
    5730          13 :                 dequeue_task(rq, p, DEQUEUE_SAVE | DEQUEUE_NOCLOCK);
    5731          21 :         if (running)
    5732          13 :                 put_prev_task(rq, p);
    5733             : 
    5734          21 :         p->static_prio = NICE_TO_PRIO(nice);
    5735          21 :         set_load_weight(p, true);
    5736          21 :         old_prio = p->prio;
    5737          21 :         p->prio = effective_prio(p);
    5738             : 
    5739          21 :         if (queued)
    5740          13 :                 enqueue_task(rq, p, ENQUEUE_RESTORE | ENQUEUE_NOCLOCK);
    5741          21 :         if (running)
    5742          13 :                 set_next_task(rq, p);
    5743             : 
    5744             :         /*
    5745             :          * If the task increased its priority or is running and
    5746             :          * lowered its priority, then reschedule its CPU:
    5747             :          */
    5748          21 :         p->sched_class->prio_changed(rq, p, old_prio);
    5749             : 
    5750          21 : out_unlock:
    5751          21 :         task_rq_unlock(rq, p, &rf);
    5752             : }
    5753             : EXPORT_SYMBOL(set_user_nice);
    5754             : 
    5755             : /*
    5756             :  * can_nice - check if a task can reduce its nice value
    5757             :  * @p: task
    5758             :  * @nice: nice value
    5759             :  */
    5760           0 : int can_nice(const struct task_struct *p, const int nice)
    5761             : {
    5762             :         /* Convert nice value [19,-20] to rlimit style value [1,40]: */
    5763           0 :         int nice_rlim = nice_to_rlimit(nice);
    5764             : 
    5765           0 :         return (nice_rlim <= task_rlimit(p, RLIMIT_NICE) ||
    5766           0 :                 capable(CAP_SYS_NICE));
    5767             : }
    5768             : 
    5769             : #ifdef __ARCH_WANT_SYS_NICE
    5770             : 
    5771             : /*
    5772             :  * sys_nice - change the priority of the current process.
    5773             :  * @increment: priority increment
    5774             :  *
    5775             :  * sys_setpriority is a more generic, but much slower function that
    5776             :  * does similar things.
    5777             :  */
    5778           0 : SYSCALL_DEFINE1(nice, int, increment)
    5779             : {
    5780           0 :         long nice, retval;
    5781             : 
    5782             :         /*
    5783             :          * Setpriority might change our priority at the same moment.
    5784             :          * We don't have to worry. Conceptually one call occurs first
    5785             :          * and we have a single winner.
    5786             :          */
    5787           0 :         increment = clamp(increment, -NICE_WIDTH, NICE_WIDTH);
    5788           0 :         nice = task_nice(current) + increment;
    5789             : 
    5790           0 :         nice = clamp_val(nice, MIN_NICE, MAX_NICE);
    5791           0 :         if (increment < 0 && !can_nice(current, nice))
    5792             :                 return -EPERM;
    5793             : 
    5794           0 :         retval = security_task_setnice(current, nice);
    5795           0 :         if (retval)
    5796             :                 return retval;
    5797             : 
    5798           0 :         set_user_nice(current, nice);
    5799           0 :         return 0;
    5800             : }
    5801             : 
    5802             : #endif
    5803             : 
    5804             : /**
    5805             :  * task_prio - return the priority value of a given task.
    5806             :  * @p: the task in question.
    5807             :  *
    5808             :  * Return: The priority value as seen by users in /proc.
    5809             :  *
    5810             :  * sched policy         return value   kernel prio    user prio/nice
    5811             :  *
    5812             :  * normal, batch, idle     [0 ... 39]  [100 ... 139]          0/[-20 ... 19]
    5813             :  * fifo, rr             [-2 ... -100]     [98 ... 0]  [1 ... 99]
    5814             :  * deadline                     -101             -1           0
    5815             :  */
    5816         139 : int task_prio(const struct task_struct *p)
    5817             : {
    5818         139 :         return p->prio - MAX_RT_PRIO;
    5819             : }
    5820             : 
    5821             : /**
    5822             :  * idle_cpu - is a given CPU idle currently?
    5823             :  * @cpu: the processor in question.
    5824             :  *
    5825             :  * Return: 1 if the CPU is currently idle. 0 otherwise.
    5826             :  */
    5827      102866 : int idle_cpu(int cpu)
    5828             : {
    5829      102866 :         struct rq *rq = cpu_rq(cpu);
    5830             : 
    5831      102866 :         if (rq->curr != rq->idle)
    5832             :                 return 0;
    5833             : 
    5834       54767 :         if (rq->nr_running)
    5835             :                 return 0;
    5836             : 
    5837             : #ifdef CONFIG_SMP
    5838       46497 :         if (rq->ttwu_pending)
    5839         209 :                 return 0;
    5840             : #endif
    5841             : 
    5842             :         return 1;
    5843             : }
    5844             : 
    5845             : /**
    5846             :  * available_idle_cpu - is a given CPU idle for enqueuing work.
    5847             :  * @cpu: the CPU in question.
    5848             :  *
    5849             :  * Return: 1 if the CPU is currently idle. 0 otherwise.
    5850             :  */
    5851       10602 : int available_idle_cpu(int cpu)
    5852             : {
    5853       10602 :         if (!idle_cpu(cpu))
    5854             :                 return 0;
    5855             : 
    5856        5387 :         if (vcpu_is_preempted(cpu))
    5857        2031 :                 return 0;
    5858             : 
    5859             :         return 1;
    5860             : }
    5861             : 
    5862             : /**
    5863             :  * idle_task - return the idle task for a given CPU.
    5864             :  * @cpu: the processor in question.
    5865             :  *
    5866             :  * Return: The idle task for the CPU @cpu.
    5867             :  */
    5868           0 : struct task_struct *idle_task(int cpu)
    5869             : {
    5870           0 :         return cpu_rq(cpu)->idle;
    5871             : }
    5872             : 
    5873             : #ifdef CONFIG_SMP
    5874             : /*
    5875             :  * This function computes an effective utilization for the given CPU, to be
    5876             :  * used for frequency selection given the linear relation: f = u * f_max.
    5877             :  *
    5878             :  * The scheduler tracks the following metrics:
    5879             :  *
    5880             :  *   cpu_util_{cfs,rt,dl,irq}()
    5881             :  *   cpu_bw_dl()
    5882             :  *
    5883             :  * Where the cfs,rt and dl util numbers are tracked with the same metric and
    5884             :  * synchronized windows and are thus directly comparable.
    5885             :  *
    5886             :  * The cfs,rt,dl utilization are the running times measured with rq->clock_task
    5887             :  * which excludes things like IRQ and steal-time. These latter are then accrued
    5888             :  * in the irq utilization.
    5889             :  *
    5890             :  * The DL bandwidth number otoh is not a measured metric but a value computed
    5891             :  * based on the task model parameters and gives the minimal utilization
    5892             :  * required to meet deadlines.
    5893             :  */
    5894           0 : unsigned long effective_cpu_util(int cpu, unsigned long util_cfs,
    5895             :                                  unsigned long max, enum cpu_util_type type,
    5896             :                                  struct task_struct *p)
    5897             : {
    5898           0 :         unsigned long dl_util, util, irq;
    5899           0 :         struct rq *rq = cpu_rq(cpu);
    5900             : 
    5901           0 :         if (!uclamp_is_used() &&
    5902           0 :             type == FREQUENCY_UTIL && rt_rq_is_runnable(&rq->rt)) {
    5903             :                 return max;
    5904             :         }
    5905             : 
    5906             :         /*
    5907             :          * Early check to see if IRQ/steal time saturates the CPU, can be
    5908             :          * because of inaccuracies in how we track these -- see
    5909             :          * update_irq_load_avg().
    5910             :          */
    5911           0 :         irq = cpu_util_irq(rq);
    5912           0 :         if (unlikely(irq >= max))
    5913             :                 return max;
    5914             : 
    5915             :         /*
    5916             :          * Because the time spend on RT/DL tasks is visible as 'lost' time to
    5917             :          * CFS tasks and we use the same metric to track the effective
    5918             :          * utilization (PELT windows are synchronized) we can directly add them
    5919             :          * to obtain the CPU's actual utilization.
    5920             :          *
    5921             :          * CFS and RT utilization can be boosted or capped, depending on
    5922             :          * utilization clamp constraints requested by currently RUNNABLE
    5923             :          * tasks.
    5924             :          * When there are no CFS RUNNABLE tasks, clamps are released and
    5925             :          * frequency will be gracefully reduced with the utilization decay.
    5926             :          */
    5927           0 :         util = util_cfs + cpu_util_rt(rq);
    5928           0 :         if (type == FREQUENCY_UTIL)
    5929           0 :                 util = uclamp_rq_util_with(rq, util, p);
    5930             : 
    5931           0 :         dl_util = cpu_util_dl(rq);
    5932             : 
    5933             :         /*
    5934             :          * For frequency selection we do not make cpu_util_dl() a permanent part
    5935             :          * of this sum because we want to use cpu_bw_dl() later on, but we need
    5936             :          * to check if the CFS+RT+DL sum is saturated (ie. no idle time) such
    5937             :          * that we select f_max when there is no idle time.
    5938             :          *
    5939             :          * NOTE: numerical errors or stop class might cause us to not quite hit
    5940             :          * saturation when we should -- something for later.
    5941             :          */
    5942           0 :         if (util + dl_util >= max)
    5943             :                 return max;
    5944             : 
    5945             :         /*
    5946             :          * OTOH, for energy computation we need the estimated running time, so
    5947             :          * include util_dl and ignore dl_bw.
    5948             :          */
    5949           0 :         if (type == ENERGY_UTIL)
    5950           0 :                 util += dl_util;
    5951             : 
    5952             :         /*
    5953             :          * There is still idle time; further improve the number by using the
    5954             :          * irq metric. Because IRQ/steal time is hidden from the task clock we
    5955             :          * need to scale the task numbers:
    5956             :          *
    5957             :          *              max - irq
    5958             :          *   U' = irq + --------- * U
    5959             :          *                 max
    5960             :          */
    5961           0 :         util = scale_irq_capacity(util, irq, max);
    5962           0 :         util += irq;
    5963             : 
    5964             :         /*
    5965             :          * Bandwidth required by DEADLINE must always be granted while, for
    5966             :          * FAIR and RT, we use blocked utilization of IDLE CPUs as a mechanism
    5967             :          * to gracefully reduce the frequency when no tasks show up for longer
    5968             :          * periods of time.
    5969             :          *
    5970             :          * Ideally we would like to set bw_dl as min/guaranteed freq and util +
    5971             :          * bw_dl as requested freq. However, cpufreq is not yet ready for such
    5972             :          * an interface. So, we only do the latter for now.
    5973             :          */
    5974           0 :         if (type == FREQUENCY_UTIL)
    5975           0 :                 util += cpu_bw_dl(rq);
    5976             : 
    5977           0 :         return min(max, util);
    5978             : }
    5979             : 
    5980           0 : unsigned long sched_cpu_util(int cpu, unsigned long max)
    5981             : {
    5982           0 :         return effective_cpu_util(cpu, cpu_util_cfs(cpu_rq(cpu)), max,
    5983             :                                   ENERGY_UTIL, NULL);
    5984             : }
    5985             : #endif /* CONFIG_SMP */
    5986             : 
    5987             : /**
    5988             :  * find_process_by_pid - find a process with a matching PID value.
    5989             :  * @pid: the pid in question.
    5990             :  *
    5991             :  * The task of @pid, if found. %NULL otherwise.
    5992             :  */
    5993           8 : static struct task_struct *find_process_by_pid(pid_t pid)
    5994             : {
    5995           8 :         return pid ? find_task_by_vpid(pid) : current;
    5996             : }
    5997             : 
    5998             : /*
    5999             :  * sched_setparam() passes in -1 for its policy, to let the functions
    6000             :  * it calls know not to change it.
    6001             :  */
    6002             : #define SETPARAM_POLICY -1
    6003             : 
    6004           4 : static void __setscheduler_params(struct task_struct *p,
    6005             :                 const struct sched_attr *attr)
    6006             : {
    6007           4 :         int policy = attr->sched_policy;
    6008             : 
    6009           4 :         if (policy == SETPARAM_POLICY)
    6010           0 :                 policy = p->policy;
    6011             : 
    6012           4 :         p->policy = policy;
    6013             : 
    6014           4 :         if (dl_policy(policy))
    6015           0 :                 __setparam_dl(p, attr);
    6016           4 :         else if (fair_policy(policy))
    6017           0 :                 p->static_prio = NICE_TO_PRIO(attr->sched_nice);
    6018             : 
    6019             :         /*
    6020             :          * __sched_setscheduler() ensures attr->sched_priority == 0 when
    6021             :          * !rt_policy. Always setting this ensures that things like
    6022             :          * getparam()/getattr() don't report silly values for !rt tasks.
    6023             :          */
    6024           4 :         p->rt_priority = attr->sched_priority;
    6025           4 :         p->normal_prio = normal_prio(p);
    6026           4 :         set_load_weight(p, true);
    6027           4 : }
    6028             : 
    6029             : /* Actually do priority change: must hold pi & rq lock. */
    6030           4 : static void __setscheduler(struct rq *rq, struct task_struct *p,
    6031             :                            const struct sched_attr *attr, bool keep_boost)
    6032             : {
    6033             :         /*
    6034             :          * If params can't change scheduling class changes aren't allowed
    6035             :          * either.
    6036             :          */
    6037           4 :         if (attr->sched_flags & SCHED_FLAG_KEEP_PARAMS)
    6038             :                 return;
    6039             : 
    6040           4 :         __setscheduler_params(p, attr);
    6041             : 
    6042             :         /*
    6043             :          * Keep a potential priority boosting if called from
    6044             :          * sched_setscheduler().
    6045             :          */
    6046           4 :         p->prio = normal_prio(p);
    6047           4 :         if (keep_boost)
    6048           4 :                 p->prio = rt_effective_prio(p, p->prio);
    6049             : 
    6050           4 :         if (dl_prio(p->prio))
    6051           0 :                 p->sched_class = &dl_sched_class;
    6052           4 :         else if (rt_prio(p->prio))
    6053           4 :                 p->sched_class = &rt_sched_class;
    6054             :         else
    6055           0 :                 p->sched_class = &fair_sched_class;
    6056             : }
    6057             : 
    6058             : /*
    6059             :  * Check the target process has a UID that matches the current process's:
    6060             :  */
    6061           0 : static bool check_same_owner(struct task_struct *p)
    6062             : {
    6063           0 :         const struct cred *cred = current_cred(), *pcred;
    6064           0 :         bool match;
    6065             : 
    6066           0 :         rcu_read_lock();
    6067           0 :         pcred = __task_cred(p);
    6068           0 :         match = (uid_eq(cred->euid, pcred->euid) ||
    6069           0 :                  uid_eq(cred->euid, pcred->uid));
    6070           0 :         rcu_read_unlock();
    6071           0 :         return match;
    6072             : }
    6073             : 
    6074          55 : static int __sched_setscheduler(struct task_struct *p,
    6075             :                                 const struct sched_attr *attr,
    6076             :                                 bool user, bool pi)
    6077             : {
    6078          55 :         int newprio = dl_policy(attr->sched_policy) ? MAX_DL_PRIO - 1 :
    6079          55 :                       MAX_RT_PRIO - 1 - attr->sched_priority;
    6080          55 :         int retval, oldprio, oldpolicy = -1, queued, running;
    6081          55 :         int new_effective_prio, policy = attr->sched_policy;
    6082          55 :         const struct sched_class *prev_class;
    6083          55 :         struct callback_head *head;
    6084          55 :         struct rq_flags rf;
    6085          55 :         int reset_on_fork;
    6086          55 :         int queue_flags = DEQUEUE_SAVE | DEQUEUE_MOVE | DEQUEUE_NOCLOCK;
    6087          55 :         struct rq *rq;
    6088             : 
    6089             :         /* The pi code expects interrupts enabled */
    6090          55 :         BUG_ON(pi && in_interrupt());
    6091          55 : recheck:
    6092             :         /* Double check policy once rq lock held: */
    6093          55 :         if (policy < 0) {
    6094           0 :                 reset_on_fork = p->sched_reset_on_fork;
    6095           0 :                 policy = oldpolicy = p->policy;
    6096             :         } else {
    6097          55 :                 reset_on_fork = !!(attr->sched_flags & SCHED_FLAG_RESET_ON_FORK);
    6098             : 
    6099          55 :                 if (!valid_policy(policy))
    6100             :                         return -EINVAL;
    6101             :         }
    6102             : 
    6103          55 :         if (attr->sched_flags & ~(SCHED_FLAG_ALL | SCHED_FLAG_SUGOV))
    6104             :                 return -EINVAL;
    6105             : 
    6106             :         /*
    6107             :          * Valid priorities for SCHED_FIFO and SCHED_RR are
    6108             :          * 1..MAX_RT_PRIO-1, valid priority for SCHED_NORMAL,
    6109             :          * SCHED_BATCH and SCHED_IDLE is 0.
    6110             :          */
    6111          55 :         if (attr->sched_priority > MAX_RT_PRIO-1)
    6112             :                 return -EINVAL;
    6113          55 :         if ((dl_policy(policy) && !__checkparam_dl(attr)) ||
    6114          55 :             (rt_policy(policy) != (attr->sched_priority != 0)))
    6115           0 :                 return -EINVAL;
    6116             : 
    6117             :         /*
    6118             :          * Allow unprivileged RT tasks to decrease priority:
    6119             :          */
    6120          55 :         if (user && !capable(CAP_SYS_NICE)) {
    6121           0 :                 if (fair_policy(policy)) {
    6122           0 :                         if (attr->sched_nice < task_nice(p) &&
    6123           0 :                             !can_nice(p, attr->sched_nice))
    6124             :                                 return -EPERM;
    6125             :                 }
    6126             : 
    6127           0 :                 if (rt_policy(policy)) {
    6128           0 :                         unsigned long rlim_rtprio =
    6129           0 :                                         task_rlimit(p, RLIMIT_RTPRIO);
    6130             : 
    6131             :                         /* Can't set/change the rt policy: */
    6132           0 :                         if (policy != p->policy && !rlim_rtprio)
    6133             :                                 return -EPERM;
    6134             : 
    6135             :                         /* Can't increase priority: */
    6136           0 :                         if (attr->sched_priority > p->rt_priority &&
    6137           0 :                             attr->sched_priority > rlim_rtprio)
    6138             :                                 return -EPERM;
    6139             :                 }
    6140             : 
    6141             :                  /*
    6142             :                   * Can't set/change SCHED_DEADLINE policy at all for now
    6143             :                   * (safest behavior); in the future we would like to allow
    6144             :                   * unprivileged DL tasks to increase their relative deadline
    6145             :                   * or reduce their runtime (both ways reducing utilization)
    6146             :                   */
    6147           0 :                 if (dl_policy(policy))
    6148             :                         return -EPERM;
    6149             : 
    6150             :                 /*
    6151             :                  * Treat SCHED_IDLE as nice 20. Only allow a switch to
    6152             :                  * SCHED_NORMAL if the RLIMIT_NICE would normally permit it.
    6153             :                  */
    6154           0 :                 if (task_has_idle_policy(p) && !idle_policy(policy)) {
    6155           0 :                         if (!can_nice(p, task_nice(p)))
    6156             :                                 return -EPERM;
    6157             :                 }
    6158             : 
    6159             :                 /* Can't change other user's priorities: */
    6160           0 :                 if (!check_same_owner(p))
    6161             :                         return -EPERM;
    6162             : 
    6163             :                 /* Normal users shall not reset the sched_reset_on_fork flag: */
    6164           0 :                 if (p->sched_reset_on_fork && !reset_on_fork)
    6165             :                         return -EPERM;
    6166             :         }
    6167             : 
    6168          55 :         if (user) {
    6169           3 :                 if (attr->sched_flags & SCHED_FLAG_SUGOV)
    6170             :                         return -EINVAL;
    6171             : 
    6172           3 :                 retval = security_task_setscheduler(p);
    6173           3 :                 if (retval)
    6174             :                         return retval;
    6175             :         }
    6176             : 
    6177             :         /* Update task specific "requested" clamps */
    6178          55 :         if (attr->sched_flags & SCHED_FLAG_UTIL_CLAMP) {
    6179          55 :                 retval = uclamp_validate(p, attr);
    6180             :                 if (retval)
    6181             :                         return retval;
    6182             :         }
    6183             : 
    6184          55 :         if (pi)
    6185             :                 cpuset_read_lock();
    6186             : 
    6187             :         /*
    6188             :          * Make sure no PI-waiters arrive (or leave) while we are
    6189             :          * changing the priority of the task:
    6190             :          *
    6191             :          * To be able to change p->policy safely, the appropriate
    6192             :          * runqueue lock must be held.
    6193             :          */
    6194          55 :         rq = task_rq_lock(p, &rf);
    6195          55 :         update_rq_clock(rq);
    6196             : 
    6197             :         /*
    6198             :          * Changing the policy of the stop threads its a very bad idea:
    6199             :          */
    6200          55 :         if (p == rq->stop) {
    6201           0 :                 retval = -EINVAL;
    6202           0 :                 goto unlock;
    6203             :         }
    6204             : 
    6205             :         /*
    6206             :          * If not changing anything there's no need to proceed further,
    6207             :          * but store a possible modification of reset_on_fork.
    6208             :          */
    6209          55 :         if (unlikely(policy == p->policy)) {
    6210          51 :                 if (fair_policy(policy) && attr->sched_nice != task_nice(p))
    6211           0 :                         goto change;
    6212          51 :                 if (rt_policy(policy) && attr->sched_priority != p->rt_priority)
    6213           0 :                         goto change;
    6214          51 :                 if (dl_policy(policy) && dl_param_changed(p, attr))
    6215           0 :                         goto change;
    6216          51 :                 if (attr->sched_flags & SCHED_FLAG_UTIL_CLAMP)
    6217           0 :                         goto change;
    6218             : 
    6219          51 :                 p->sched_reset_on_fork = reset_on_fork;
    6220          51 :                 retval = 0;
    6221          51 :                 goto unlock;
    6222             :         }
    6223           4 : change:
    6224             : 
    6225           4 :         if (user) {
    6226             : #ifdef CONFIG_RT_GROUP_SCHED
    6227             :                 /*
    6228             :                  * Do not allow realtime tasks into groups that have no runtime
    6229             :                  * assigned.
    6230             :                  */
    6231             :                 if (rt_bandwidth_enabled() && rt_policy(policy) &&
    6232             :                                 task_group(p)->rt_bandwidth.rt_runtime == 0 &&
    6233             :                                 !task_group_is_autogroup(task_group(p))) {
    6234             :                         retval = -EPERM;
    6235             :                         goto unlock;
    6236             :                 }
    6237             : #endif
    6238             : #ifdef CONFIG_SMP
    6239           0 :                 if (dl_bandwidth_enabled() && dl_policy(policy) &&
    6240           0 :                                 !(attr->sched_flags & SCHED_FLAG_SUGOV)) {
    6241           0 :                         cpumask_t *span = rq->rd->span;
    6242             : 
    6243             :                         /*
    6244             :                          * Don't allow tasks with an affinity mask smaller than
    6245             :                          * the entire root_domain to become SCHED_DEADLINE. We
    6246             :                          * will also fail if there's no bandwidth available.
    6247             :                          */
    6248           0 :                         if (!cpumask_subset(span, p->cpus_ptr) ||
    6249           0 :                             rq->rd->dl_bw.bw == 0) {
    6250           0 :                                 retval = -EPERM;
    6251           0 :                                 goto unlock;
    6252             :                         }
    6253             :                 }
    6254             : #endif
    6255             :         }
    6256             : 
    6257             :         /* Re-check policy now with rq lock held: */
    6258           4 :         if (unlikely(oldpolicy != -1 && oldpolicy != p->policy)) {
    6259           0 :                 policy = oldpolicy = -1;
    6260           0 :                 task_rq_unlock(rq, p, &rf);
    6261           0 :                 if (pi)
    6262             :                         cpuset_read_unlock();
    6263           0 :                 goto recheck;
    6264             :         }
    6265             : 
    6266             :         /*
    6267             :          * If setscheduling to SCHED_DEADLINE (or changing the parameters
    6268             :          * of a SCHED_DEADLINE task) we need to check if enough bandwidth
    6269             :          * is available.
    6270             :          */
    6271           4 :         if ((dl_policy(policy) || dl_task(p)) && sched_dl_overflow(p, policy, attr)) {
    6272           0 :                 retval = -EBUSY;
    6273           0 :                 goto unlock;
    6274             :         }
    6275             : 
    6276           4 :         p->sched_reset_on_fork = reset_on_fork;
    6277           4 :         oldprio = p->prio;
    6278             : 
    6279           4 :         if (pi) {
    6280             :                 /*
    6281             :                  * Take priority boosted tasks into account. If the new
    6282             :                  * effective priority is unchanged, we just store the new
    6283             :                  * normal parameters and do not touch the scheduler class and
    6284             :                  * the runqueue. This will be done when the task deboost
    6285             :                  * itself.
    6286             :                  */
    6287           4 :                 new_effective_prio = rt_effective_prio(p, newprio);
    6288           4 :                 if (new_effective_prio == oldprio)
    6289           0 :                         queue_flags &= ~DEQUEUE_MOVE;
    6290             :         }
    6291             : 
    6292           4 :         queued = task_on_rq_queued(p);
    6293           4 :         running = task_current(rq, p);
    6294           4 :         if (queued)
    6295           0 :                 dequeue_task(rq, p, queue_flags);
    6296           4 :         if (running)
    6297           0 :                 put_prev_task(rq, p);
    6298             : 
    6299           4 :         prev_class = p->sched_class;
    6300             : 
    6301           4 :         __setscheduler(rq, p, attr, pi);
    6302           4 :         __setscheduler_uclamp(p, attr);
    6303             : 
    6304           4 :         if (queued) {
    6305             :                 /*
    6306             :                  * We enqueue to tail when the priority of a task is
    6307             :                  * increased (user space view).
    6308             :                  */
    6309           0 :                 if (oldprio < p->prio)
    6310           0 :                         queue_flags |= ENQUEUE_HEAD;
    6311             : 
    6312           0 :                 enqueue_task(rq, p, queue_flags);
    6313             :         }
    6314           4 :         if (running)
    6315           0 :                 set_next_task(rq, p);
    6316             : 
    6317           4 :         check_class_changed(rq, p, prev_class, oldprio);
    6318             : 
    6319             :         /* Avoid rq from going away on us: */
    6320           4 :         preempt_disable();
    6321           4 :         head = splice_balance_callbacks(rq);
    6322           4 :         task_rq_unlock(rq, p, &rf);
    6323             : 
    6324           4 :         if (pi) {
    6325           4 :                 cpuset_read_unlock();
    6326           4 :                 rt_mutex_adjust_pi(p);
    6327             :         }
    6328             : 
    6329             :         /* Run balance callbacks after we've adjusted the PI chain: */
    6330           4 :         balance_callbacks(rq, head);
    6331           4 :         preempt_enable();
    6332             : 
    6333           4 :         return 0;
    6334             : 
    6335          51 : unlock:
    6336          51 :         task_rq_unlock(rq, p, &rf);
    6337          51 :         if (pi)
    6338             :                 cpuset_read_unlock();
    6339          51 :         return retval;
    6340             : }
    6341             : 
    6342          55 : static int _sched_setscheduler(struct task_struct *p, int policy,
    6343             :                                const struct sched_param *param, bool check)
    6344             : {
    6345          55 :         struct sched_attr attr = {
    6346             :                 .sched_policy   = policy,
    6347          55 :                 .sched_priority = param->sched_priority,
    6348          55 :                 .sched_nice     = PRIO_TO_NICE(p->static_prio),
    6349             :         };
    6350             : 
    6351             :         /* Fixup the legacy SCHED_RESET_ON_FORK hack. */
    6352          55 :         if ((policy != SETPARAM_POLICY) && (policy & SCHED_RESET_ON_FORK)) {
    6353           0 :                 attr.sched_flags |= SCHED_FLAG_RESET_ON_FORK;
    6354           0 :                 policy &= ~SCHED_RESET_ON_FORK;
    6355           0 :                 attr.sched_policy = policy;
    6356             :         }
    6357             : 
    6358          55 :         return __sched_setscheduler(p, &attr, check, true);
    6359             : }
    6360             : /**
    6361             :  * sched_setscheduler - change the scheduling policy and/or RT priority of a thread.
    6362             :  * @p: the task in question.
    6363             :  * @policy: new policy.
    6364             :  * @param: structure containing the new RT priority.
    6365             :  *
    6366             :  * Use sched_set_fifo(), read its comment.
    6367             :  *
    6368             :  * Return: 0 on success. An error code otherwise.
    6369             :  *
    6370             :  * NOTE that the task may be already dead.
    6371             :  */
    6372           3 : int sched_setscheduler(struct task_struct *p, int policy,
    6373             :                        const struct sched_param *param)
    6374             : {
    6375           0 :         return _sched_setscheduler(p, policy, param, true);
    6376             : }
    6377             : 
    6378           0 : int sched_setattr(struct task_struct *p, const struct sched_attr *attr)
    6379             : {
    6380           0 :         return __sched_setscheduler(p, attr, true, true);
    6381             : }
    6382             : 
    6383           0 : int sched_setattr_nocheck(struct task_struct *p, const struct sched_attr *attr)
    6384             : {
    6385           0 :         return __sched_setscheduler(p, attr, false, true);
    6386             : }
    6387             : 
    6388             : /**
    6389             :  * sched_setscheduler_nocheck - change the scheduling policy and/or RT priority of a thread from kernelspace.
    6390             :  * @p: the task in question.
    6391             :  * @policy: new policy.
    6392             :  * @param: structure containing the new RT priority.
    6393             :  *
    6394             :  * Just like sched_setscheduler, only don't bother checking if the
    6395             :  * current context has permission.  For example, this is needed in
    6396             :  * stop_machine(): we create temporary high priority worker threads,
    6397             :  * but our caller might not have that capability.
    6398             :  *
    6399             :  * Return: 0 on success. An error code otherwise.
    6400             :  */
    6401          52 : int sched_setscheduler_nocheck(struct task_struct *p, int policy,
    6402             :                                const struct sched_param *param)
    6403             : {
    6404          52 :         return _sched_setscheduler(p, policy, param, false);
    6405             : }
    6406             : 
    6407             : /*
    6408             :  * SCHED_FIFO is a broken scheduler model; that is, it is fundamentally
    6409             :  * incapable of resource management, which is the one thing an OS really should
    6410             :  * be doing.
    6411             :  *
    6412             :  * This is of course the reason it is limited to privileged users only.
    6413             :  *
    6414             :  * Worse still; it is fundamentally impossible to compose static priority
    6415             :  * workloads. You cannot take two correctly working static prio workloads
    6416             :  * and smash them together and still expect them to work.
    6417             :  *
    6418             :  * For this reason 'all' FIFO tasks the kernel creates are basically at:
    6419             :  *
    6420             :  *   MAX_RT_PRIO / 2
    6421             :  *
    6422             :  * The administrator _MUST_ configure the system, the kernel simply doesn't
    6423             :  * know enough information to make a sensible choice.
    6424             :  */
    6425           0 : void sched_set_fifo(struct task_struct *p)
    6426             : {
    6427           0 :         struct sched_param sp = { .sched_priority = MAX_RT_PRIO / 2 };
    6428           0 :         WARN_ON_ONCE(sched_setscheduler_nocheck(p, SCHED_FIFO, &sp) != 0);
    6429           0 : }
    6430             : EXPORT_SYMBOL_GPL(sched_set_fifo);
    6431             : 
    6432             : /*
    6433             :  * For when you don't much care about FIFO, but want to be above SCHED_NORMAL.
    6434             :  */
    6435           0 : void sched_set_fifo_low(struct task_struct *p)
    6436             : {
    6437           0 :         struct sched_param sp = { .sched_priority = 1 };
    6438           0 :         WARN_ON_ONCE(sched_setscheduler_nocheck(p, SCHED_FIFO, &sp) != 0);
    6439           0 : }
    6440             : EXPORT_SYMBOL_GPL(sched_set_fifo_low);
    6441             : 
    6442           0 : void sched_set_normal(struct task_struct *p, int nice)
    6443             : {
    6444           0 :         struct sched_attr attr = {
    6445             :                 .sched_policy = SCHED_NORMAL,
    6446             :                 .sched_nice = nice,
    6447             :         };
    6448           0 :         WARN_ON_ONCE(sched_setattr_nocheck(p, &attr) != 0);
    6449           0 : }
    6450             : EXPORT_SYMBOL_GPL(sched_set_normal);
    6451             : 
    6452             : static int
    6453           3 : do_sched_setscheduler(pid_t pid, int policy, struct sched_param __user *param)
    6454             : {
    6455           3 :         struct sched_param lparam;
    6456           3 :         struct task_struct *p;
    6457           3 :         int retval;
    6458             : 
    6459           3 :         if (!param || pid < 0)
    6460             :                 return -EINVAL;
    6461           3 :         if (copy_from_user(&lparam, param, sizeof(struct sched_param)))
    6462             :                 return -EFAULT;
    6463             : 
    6464           3 :         rcu_read_lock();
    6465           3 :         retval = -ESRCH;
    6466           3 :         p = find_process_by_pid(pid);
    6467           3 :         if (likely(p))
    6468           3 :                 get_task_struct(p);
    6469           3 :         rcu_read_unlock();
    6470             : 
    6471           3 :         if (likely(p)) {
    6472           3 :                 retval = sched_setscheduler(p, policy, &lparam);
    6473           3 :                 put_task_struct(p);
    6474             :         }
    6475             : 
    6476             :         return retval;
    6477             : }
    6478             : 
    6479             : /*
    6480             :  * Mimics kernel/events/core.c perf_copy_attr().
    6481             :  */
    6482           0 : static int sched_copy_attr(struct sched_attr __user *uattr, struct sched_attr *attr)
    6483             : {
    6484           0 :         u32 size;
    6485           0 :         int ret;
    6486             : 
    6487             :         /* Zero the full structure, so that a short copy will be nice: */
    6488           0 :         memset(attr, 0, sizeof(*attr));
    6489             : 
    6490           0 :         ret = get_user(size, &uattr->size);
    6491           0 :         if (ret)
    6492             :                 return ret;
    6493             : 
    6494             :         /* ABI compatibility quirk: */
    6495           0 :         if (!size)
    6496           0 :                 size = SCHED_ATTR_SIZE_VER0;
    6497           0 :         if (size < SCHED_ATTR_SIZE_VER0 || size > PAGE_SIZE)
    6498           0 :                 goto err_size;
    6499             : 
    6500           0 :         ret = copy_struct_from_user(attr, sizeof(*attr), uattr, size);
    6501           0 :         if (ret) {
    6502           0 :                 if (ret == -E2BIG)
    6503           0 :                         goto err_size;
    6504             :                 return ret;
    6505             :         }
    6506             : 
    6507           0 :         if ((attr->sched_flags & SCHED_FLAG_UTIL_CLAMP) &&
    6508             :             size < SCHED_ATTR_SIZE_VER1)
    6509             :                 return -EINVAL;
    6510             : 
    6511             :         /*
    6512             :          * XXX: Do we want to be lenient like existing syscalls; or do we want
    6513             :          * to be strict and return an error on out-of-bounds values?
    6514             :          */
    6515           0 :         attr->sched_nice = clamp(attr->sched_nice, MIN_NICE, MAX_NICE);
    6516             : 
    6517           0 :         return 0;
    6518             : 
    6519           0 : err_size:
    6520           0 :         put_user(sizeof(*attr), &uattr->size);
    6521           0 :         return -E2BIG;
    6522             : }
    6523             : 
    6524             : /**
    6525             :  * sys_sched_setscheduler - set/change the scheduler policy and RT priority
    6526             :  * @pid: the pid in question.
    6527             :  * @policy: new policy.
    6528             :  * @param: structure containing the new RT priority.
    6529             :  *
    6530             :  * Return: 0 on success. An error code otherwise.
    6531             :  */
    6532           6 : SYSCALL_DEFINE3(sched_setscheduler, pid_t, pid, int, policy, struct sched_param __user *, param)
    6533             : {
    6534           3 :         if (policy < 0)
    6535             :                 return -EINVAL;
    6536             : 
    6537           3 :         return do_sched_setscheduler(pid, policy, param);
    6538             : }
    6539             : 
    6540             : /**
    6541             :  * sys_sched_setparam - set/change the RT priority of a thread
    6542             :  * @pid: the pid in question.
    6543             :  * @param: structure containing the new RT priority.
    6544             :  *
    6545             :  * Return: 0 on success. An error code otherwise.
    6546             :  */
    6547           0 : SYSCALL_DEFINE2(sched_setparam, pid_t, pid, struct sched_param __user *, param)
    6548             : {
    6549           0 :         return do_sched_setscheduler(pid, SETPARAM_POLICY, param);
    6550             : }
    6551             : 
    6552             : /**
    6553             :  * sys_sched_setattr - same as above, but with extended sched_attr
    6554             :  * @pid: the pid in question.
    6555             :  * @uattr: structure containing the extended parameters.
    6556             :  * @flags: for future extension.
    6557             :  */
    6558           0 : SYSCALL_DEFINE3(sched_setattr, pid_t, pid, struct sched_attr __user *, uattr,
    6559             :                                unsigned int, flags)
    6560             : {
    6561           0 :         struct sched_attr attr;
    6562           0 :         struct task_struct *p;
    6563           0 :         int retval;
    6564             : 
    6565           0 :         if (!uattr || pid < 0 || flags)
    6566             :                 return -EINVAL;
    6567             : 
    6568           0 :         retval = sched_copy_attr(uattr, &attr);
    6569           0 :         if (retval)
    6570           0 :                 return retval;
    6571             : 
    6572           0 :         if ((int)attr.sched_policy < 0)
    6573             :                 return -EINVAL;
    6574           0 :         if (attr.sched_flags & SCHED_FLAG_KEEP_POLICY)
    6575           0 :                 attr.sched_policy = SETPARAM_POLICY;
    6576             : 
    6577           0 :         rcu_read_lock();
    6578           0 :         retval = -ESRCH;
    6579           0 :         p = find_process_by_pid(pid);
    6580           0 :         if (likely(p))
    6581           0 :                 get_task_struct(p);
    6582           0 :         rcu_read_unlock();
    6583             : 
    6584           0 :         if (likely(p)) {
    6585           0 :                 retval = sched_setattr(p, &attr);
    6586           0 :                 put_task_struct(p);
    6587             :         }
    6588             : 
    6589           0 :         return retval;
    6590             : }
    6591             : 
    6592             : /**
    6593             :  * sys_sched_getscheduler - get the policy (scheduling class) of a thread
    6594             :  * @pid: the pid in question.
    6595             :  *
    6596             :  * Return: On success, the policy of the thread. Otherwise, a negative error
    6597             :  * code.
    6598             :  */
    6599           4 : SYSCALL_DEFINE1(sched_getscheduler, pid_t, pid)
    6600             : {
    6601           2 :         struct task_struct *p;
    6602           2 :         int retval;
    6603             : 
    6604           2 :         if (pid < 0)
    6605             :                 return -EINVAL;
    6606             : 
    6607           2 :         retval = -ESRCH;
    6608           2 :         rcu_read_lock();
    6609           2 :         p = find_process_by_pid(pid);
    6610           2 :         if (p) {
    6611           2 :                 retval = security_task_getscheduler(p);
    6612           2 :                 if (!retval)
    6613           2 :                         retval = p->policy
    6614           2 :                                 | (p->sched_reset_on_fork ? SCHED_RESET_ON_FORK : 0);
    6615             :         }
    6616           2 :         rcu_read_unlock();
    6617           2 :         return retval;
    6618             : }
    6619             : 
    6620             : /**
    6621             :  * sys_sched_getparam - get the RT priority of a thread
    6622             :  * @pid: the pid in question.
    6623             :  * @param: structure containing the RT priority.
    6624             :  *
    6625             :  * Return: On success, 0 and the RT priority is in @param. Otherwise, an error
    6626             :  * code.
    6627             :  */
    6628           4 : SYSCALL_DEFINE2(sched_getparam, pid_t, pid, struct sched_param __user *, param)
    6629             : {
    6630           2 :         struct sched_param lp = { .sched_priority = 0 };
    6631           2 :         struct task_struct *p;
    6632           2 :         int retval;
    6633             : 
    6634           2 :         if (!param || pid < 0)
    6635             :                 return -EINVAL;
    6636             : 
    6637           2 :         rcu_read_lock();
    6638           2 :         p = find_process_by_pid(pid);
    6639           2 :         retval = -ESRCH;
    6640           2 :         if (!p)
    6641           0 :                 goto out_unlock;
    6642             : 
    6643           2 :         retval = security_task_getscheduler(p);
    6644           2 :         if (retval)
    6645           0 :                 goto out_unlock;
    6646             : 
    6647           2 :         if (task_has_rt_policy(p))
    6648           0 :                 lp.sched_priority = p->rt_priority;
    6649           2 :         rcu_read_unlock();
    6650             : 
    6651             :         /*
    6652             :          * This one might sleep, we cannot do it with a spinlock held ...
    6653             :          */
    6654           2 :         retval = copy_to_user(param, &lp, sizeof(*param)) ? -EFAULT : 0;
    6655             : 
    6656           2 :         return retval;
    6657             : 
    6658           0 : out_unlock:
    6659           0 :         rcu_read_unlock();
    6660           0 :         return retval;
    6661             : }
    6662             : 
    6663             : /*
    6664             :  * Copy the kernel size attribute structure (which might be larger
    6665             :  * than what user-space knows about) to user-space.
    6666             :  *
    6667             :  * Note that all cases are valid: user-space buffer can be larger or
    6668             :  * smaller than the kernel-space buffer. The usual case is that both
    6669             :  * have the same size.
    6670             :  */
    6671             : static int
    6672           0 : sched_attr_copy_to_user(struct sched_attr __user *uattr,
    6673             :                         struct sched_attr *kattr,
    6674             :                         unsigned int usize)
    6675             : {
    6676           0 :         unsigned int ksize = sizeof(*kattr);
    6677             : 
    6678           0 :         if (!access_ok(uattr, usize))
    6679             :                 return -EFAULT;
    6680             : 
    6681             :         /*
    6682             :          * sched_getattr() ABI forwards and backwards compatibility:
    6683             :          *
    6684             :          * If usize == ksize then we just copy everything to user-space and all is good.
    6685             :          *
    6686             :          * If usize < ksize then we only copy as much as user-space has space for,
    6687             :          * this keeps ABI compatibility as well. We skip the rest.
    6688             :          *
    6689             :          * If usize > ksize then user-space is using a newer version of the ABI,
    6690             :          * which part the kernel doesn't know about. Just ignore it - tooling can
    6691             :          * detect the kernel's knowledge of attributes from the attr->size value
    6692             :          * which is set to ksize in this case.
    6693             :          */
    6694           0 :         kattr->size = min(usize, ksize);
    6695             : 
    6696           0 :         if (copy_to_user(uattr, kattr, kattr->size))
    6697           0 :                 return -EFAULT;
    6698             : 
    6699             :         return 0;
    6700             : }
    6701             : 
    6702             : /**
    6703             :  * sys_sched_getattr - similar to sched_getparam, but with sched_attr
    6704             :  * @pid: the pid in question.
    6705             :  * @uattr: structure containing the extended parameters.
    6706             :  * @usize: sizeof(attr) for fwd/bwd comp.
    6707             :  * @flags: for future extension.
    6708             :  */
    6709           0 : SYSCALL_DEFINE4(sched_getattr, pid_t, pid, struct sched_attr __user *, uattr,
    6710             :                 unsigned int, usize, unsigned int, flags)
    6711             : {
    6712           0 :         struct sched_attr kattr = { };
    6713           0 :         struct task_struct *p;
    6714           0 :         int retval;
    6715             : 
    6716           0 :         if (!uattr || pid < 0 || usize > PAGE_SIZE ||
    6717           0 :             usize < SCHED_ATTR_SIZE_VER0 || flags)
    6718             :                 return -EINVAL;
    6719             : 
    6720           0 :         rcu_read_lock();
    6721           0 :         p = find_process_by_pid(pid);
    6722           0 :         retval = -ESRCH;
    6723           0 :         if (!p)
    6724           0 :                 goto out_unlock;
    6725             : 
    6726           0 :         retval = security_task_getscheduler(p);
    6727           0 :         if (retval)
    6728           0 :                 goto out_unlock;
    6729             : 
    6730           0 :         kattr.sched_policy = p->policy;
    6731           0 :         if (p->sched_reset_on_fork)
    6732           0 :                 kattr.sched_flags |= SCHED_FLAG_RESET_ON_FORK;
    6733           0 :         if (task_has_dl_policy(p))
    6734           0 :                 __getparam_dl(p, &kattr);
    6735           0 :         else if (task_has_rt_policy(p))
    6736           0 :                 kattr.sched_priority = p->rt_priority;
    6737             :         else
    6738           0 :                 kattr.sched_nice = task_nice(p);
    6739             : 
    6740             : #ifdef CONFIG_UCLAMP_TASK
    6741             :         /*
    6742             :          * This could race with another potential updater, but this is fine
    6743             :          * because it'll correctly read the old or the new value. We don't need
    6744             :          * to guarantee who wins the race as long as it doesn't return garbage.
    6745             :          */
    6746             :         kattr.sched_util_min = p->uclamp_req[UCLAMP_MIN].value;
    6747             :         kattr.sched_util_max = p->uclamp_req[UCLAMP_MAX].value;
    6748             : #endif
    6749             : 
    6750           0 :         rcu_read_unlock();
    6751             : 
    6752           0 :         return sched_attr_copy_to_user(uattr, &kattr, usize);
    6753             : 
    6754           0 : out_unlock:
    6755           0 :         rcu_read_unlock();
    6756           0 :         return retval;
    6757             : }
    6758             : 
    6759           0 : long sched_setaffinity(pid_t pid, const struct cpumask *in_mask)
    6760             : {
    6761           0 :         cpumask_var_t cpus_allowed, new_mask;
    6762           0 :         struct task_struct *p;
    6763           0 :         int retval;
    6764             : 
    6765           0 :         rcu_read_lock();
    6766             : 
    6767           0 :         p = find_process_by_pid(pid);
    6768           0 :         if (!p) {
    6769           0 :                 rcu_read_unlock();
    6770           0 :                 return -ESRCH;
    6771             :         }
    6772             : 
    6773             :         /* Prevent p going away */
    6774           0 :         get_task_struct(p);
    6775           0 :         rcu_read_unlock();
    6776             : 
    6777           0 :         if (p->flags & PF_NO_SETAFFINITY) {
    6778           0 :                 retval = -EINVAL;
    6779           0 :                 goto out_put_task;
    6780             :         }
    6781           0 :         if (!alloc_cpumask_var(&cpus_allowed, GFP_KERNEL)) {
    6782             :                 retval = -ENOMEM;
    6783             :                 goto out_put_task;
    6784             :         }
    6785           0 :         if (!alloc_cpumask_var(&new_mask, GFP_KERNEL)) {
    6786             :                 retval = -ENOMEM;
    6787             :                 goto out_free_cpus_allowed;
    6788             :         }
    6789           0 :         retval = -EPERM;
    6790           0 :         if (!check_same_owner(p)) {
    6791           0 :                 rcu_read_lock();
    6792           0 :                 if (!ns_capable(__task_cred(p)->user_ns, CAP_SYS_NICE)) {
    6793           0 :                         rcu_read_unlock();
    6794           0 :                         goto out_free_new_mask;
    6795             :                 }
    6796           0 :                 rcu_read_unlock();
    6797             :         }
    6798             : 
    6799           0 :         retval = security_task_setscheduler(p);
    6800           0 :         if (retval)
    6801           0 :                 goto out_free_new_mask;
    6802             : 
    6803             : 
    6804           0 :         cpuset_cpus_allowed(p, cpus_allowed);
    6805           0 :         cpumask_and(new_mask, in_mask, cpus_allowed);
    6806             : 
    6807             :         /*
    6808             :          * Since bandwidth control happens on root_domain basis,
    6809             :          * if admission test is enabled, we only admit -deadline
    6810             :          * tasks allowed to run on all the CPUs in the task's
    6811             :          * root_domain.
    6812             :          */
    6813             : #ifdef CONFIG_SMP
    6814           0 :         if (task_has_dl_policy(p) && dl_bandwidth_enabled()) {
    6815           0 :                 rcu_read_lock();
    6816           0 :                 if (!cpumask_subset(task_rq(p)->rd->span, new_mask)) {
    6817           0 :                         retval = -EBUSY;
    6818           0 :                         rcu_read_unlock();
    6819           0 :                         goto out_free_new_mask;
    6820             :                 }
    6821           0 :                 rcu_read_unlock();
    6822             :         }
    6823             : #endif
    6824           0 : again:
    6825           0 :         retval = __set_cpus_allowed_ptr(p, new_mask, SCA_CHECK);
    6826             : 
    6827           0 :         if (!retval) {
    6828           0 :                 cpuset_cpus_allowed(p, cpus_allowed);
    6829           0 :                 if (!cpumask_subset(new_mask, cpus_allowed)) {
    6830             :                         /*
    6831             :                          * We must have raced with a concurrent cpuset
    6832             :                          * update. Just reset the cpus_allowed to the
    6833             :                          * cpuset's cpus_allowed
    6834             :                          */
    6835           0 :                         cpumask_copy(new_mask, cpus_allowed);
    6836           0 :                         goto again;
    6837             :                 }
    6838             :         }
    6839           0 : out_free_new_mask:
    6840           0 :         free_cpumask_var(new_mask);
    6841           0 : out_free_cpus_allowed:
    6842           0 :         free_cpumask_var(cpus_allowed);
    6843           0 : out_put_task:
    6844           0 :         put_task_struct(p);
    6845           0 :         return retval;
    6846             : }
    6847             : 
    6848           0 : static int get_user_cpu_mask(unsigned long __user *user_mask_ptr, unsigned len,
    6849             :                              struct cpumask *new_mask)
    6850             : {
    6851           0 :         if (len < cpumask_size())
    6852           0 :                 cpumask_clear(new_mask);
    6853           0 :         else if (len > cpumask_size())
    6854           0 :                 len = cpumask_size();
    6855             : 
    6856           0 :         return copy_from_user(new_mask, user_mask_ptr, len) ? -EFAULT : 0;
    6857             : }
    6858             : 
    6859             : /**
    6860             :  * sys_sched_setaffinity - set the CPU affinity of a process
    6861             :  * @pid: pid of the process
    6862             :  * @len: length in bytes of the bitmask pointed to by user_mask_ptr
    6863             :  * @user_mask_ptr: user-space pointer to the new CPU mask
    6864             :  *
    6865             :  * Return: 0 on success. An error code otherwise.
    6866             :  */
    6867           0 : SYSCALL_DEFINE3(sched_setaffinity, pid_t, pid, unsigned int, len,
    6868             :                 unsigned long __user *, user_mask_ptr)
    6869             : {
    6870           0 :         cpumask_var_t new_mask;
    6871           0 :         int retval;
    6872             : 
    6873           0 :         if (!alloc_cpumask_var(&new_mask, GFP_KERNEL))
    6874             :                 return -ENOMEM;
    6875             : 
    6876           0 :         retval = get_user_cpu_mask(user_mask_ptr, len, new_mask);
    6877           0 :         if (retval == 0)
    6878           0 :                 retval = sched_setaffinity(pid, new_mask);
    6879           0 :         free_cpumask_var(new_mask);
    6880           0 :         return retval;
    6881             : }
    6882             : 
    6883           1 : long sched_getaffinity(pid_t pid, struct cpumask *mask)
    6884             : {
    6885           1 :         struct task_struct *p;
    6886           1 :         unsigned long flags;
    6887           1 :         int retval;
    6888             : 
    6889           1 :         rcu_read_lock();
    6890             : 
    6891           1 :         retval = -ESRCH;
    6892           1 :         p = find_process_by_pid(pid);
    6893           1 :         if (!p)
    6894           0 :                 goto out_unlock;
    6895             : 
    6896           1 :         retval = security_task_getscheduler(p);
    6897           1 :         if (retval)
    6898           0 :                 goto out_unlock;
    6899             : 
    6900           1 :         raw_spin_lock_irqsave(&p->pi_lock, flags);
    6901           1 :         cpumask_and(mask, &p->cpus_mask, cpu_active_mask);
    6902           1 :         raw_spin_unlock_irqrestore(&p->pi_lock, flags);
    6903             : 
    6904           1 : out_unlock:
    6905           1 :         rcu_read_unlock();
    6906             : 
    6907           1 :         return retval;
    6908             : }
    6909             : 
    6910             : /**
    6911             :  * sys_sched_getaffinity - get the CPU affinity of a process
    6912             :  * @pid: pid of the process
    6913             :  * @len: length in bytes of the bitmask pointed to by user_mask_ptr
    6914             :  * @user_mask_ptr: user-space pointer to hold the current CPU mask
    6915             :  *
    6916             :  * Return: size of CPU mask copied to user_mask_ptr on success. An
    6917             :  * error code otherwise.
    6918             :  */
    6919           2 : SYSCALL_DEFINE3(sched_getaffinity, pid_t, pid, unsigned int, len,
    6920             :                 unsigned long __user *, user_mask_ptr)
    6921             : {
    6922           1 :         int ret;
    6923           1 :         cpumask_var_t mask;
    6924             : 
    6925           1 :         if ((len * BITS_PER_BYTE) < nr_cpu_ids)
    6926             :                 return -EINVAL;
    6927           1 :         if (len & (sizeof(unsigned long)-1))
    6928             :                 return -EINVAL;
    6929             : 
    6930           1 :         if (!alloc_cpumask_var(&mask, GFP_KERNEL))
    6931             :                 return -ENOMEM;
    6932             : 
    6933           1 :         ret = sched_getaffinity(pid, mask);
    6934           1 :         if (ret == 0) {
    6935           1 :                 unsigned int retlen = min(len, cpumask_size());
    6936             : 
    6937           2 :                 if (copy_to_user(user_mask_ptr, mask, retlen))
    6938             :                         ret = -EFAULT;
    6939             :                 else
    6940           1 :                         ret = retlen;
    6941             :         }
    6942           1 :         free_cpumask_var(mask);
    6943             : 
    6944           1 :         return ret;
    6945             : }
    6946             : 
    6947           0 : static void do_sched_yield(void)
    6948             : {
    6949           0 :         struct rq_flags rf;
    6950           0 :         struct rq *rq;
    6951             : 
    6952           0 :         rq = this_rq_lock_irq(&rf);
    6953             : 
    6954           0 :         schedstat_inc(rq->yld_count);
    6955           0 :         current->sched_class->yield_task(rq);
    6956             : 
    6957           0 :         preempt_disable();
    6958           0 :         rq_unlock_irq(rq, &rf);
    6959           0 :         sched_preempt_enable_no_resched();
    6960             : 
    6961           0 :         schedule();
    6962           0 : }
    6963             : 
    6964             : /**
    6965             :  * sys_sched_yield - yield the current processor to other threads.
    6966             :  *
    6967             :  * This function yields the current CPU to other tasks. If there are no
    6968             :  * other threads running on this CPU then this function will return.
    6969             :  *
    6970             :  * Return: 0.
    6971             :  */
    6972           0 : SYSCALL_DEFINE0(sched_yield)
    6973             : {
    6974           0 :         do_sched_yield();
    6975           0 :         return 0;
    6976             : }
    6977             : 
    6978             : #if !defined(CONFIG_PREEMPTION) || defined(CONFIG_PREEMPT_DYNAMIC)
    6979      486332 : int __sched __cond_resched(void)
    6980             : {
    6981      486332 :         if (should_resched(0)) {
    6982        2536 :                 preempt_schedule_common();
    6983        2536 :                 return 1;
    6984             :         }
    6985             : #ifndef CONFIG_PREEMPT_RCU
    6986      483796 :         rcu_all_qs();
    6987             : #endif
    6988      483796 :         return 0;
    6989             : }
    6990             : EXPORT_SYMBOL(__cond_resched);
    6991             : #endif
    6992             : 
    6993             : #ifdef CONFIG_PREEMPT_DYNAMIC
    6994             : DEFINE_STATIC_CALL_RET0(cond_resched, __cond_resched);
    6995             : EXPORT_STATIC_CALL_TRAMP(cond_resched);
    6996             : 
    6997             : DEFINE_STATIC_CALL_RET0(might_resched, __cond_resched);
    6998             : EXPORT_STATIC_CALL_TRAMP(might_resched);
    6999             : #endif
    7000             : 
    7001             : /*
    7002             :  * __cond_resched_lock() - if a reschedule is pending, drop the given lock,
    7003             :  * call schedule, and on return reacquire the lock.
    7004             :  *
    7005             :  * This works OK both with and without CONFIG_PREEMPTION. We do strange low-level
    7006             :  * operations here to prevent schedule() from being called twice (once via
    7007             :  * spin_unlock(), once by hand).
    7008             :  */
    7009        1656 : int __cond_resched_lock(spinlock_t *lock)
    7010             : {
    7011        1656 :         int resched = should_resched(PREEMPT_LOCK_OFFSET);
    7012        1656 :         int ret = 0;
    7013             : 
    7014        3312 :         lockdep_assert_held(lock);
    7015             : 
    7016        1656 :         if (spin_needbreak(lock) || resched) {
    7017           1 :                 spin_unlock(lock);
    7018           1 :                 if (resched)
    7019           1 :                         preempt_schedule_common();
    7020             :                 else
    7021             :                         cpu_relax();
    7022           1 :                 ret = 1;
    7023           1 :                 spin_lock(lock);
    7024             :         }
    7025        1656 :         return ret;
    7026             : }
    7027             : EXPORT_SYMBOL(__cond_resched_lock);
    7028             : 
    7029           0 : int __cond_resched_rwlock_read(rwlock_t *lock)
    7030             : {
    7031           0 :         int resched = should_resched(PREEMPT_LOCK_OFFSET);
    7032           0 :         int ret = 0;
    7033             : 
    7034           0 :         lockdep_assert_held_read(lock);
    7035             : 
    7036           0 :         if (rwlock_needbreak(lock) || resched) {
    7037           0 :                 read_unlock(lock);
    7038           0 :                 if (resched)
    7039           0 :                         preempt_schedule_common();
    7040             :                 else
    7041             :                         cpu_relax();
    7042           0 :                 ret = 1;
    7043           0 :                 read_lock(lock);
    7044             :         }
    7045           0 :         return ret;
    7046             : }
    7047             : EXPORT_SYMBOL(__cond_resched_rwlock_read);
    7048             : 
    7049           0 : int __cond_resched_rwlock_write(rwlock_t *lock)
    7050             : {
    7051           0 :         int resched = should_resched(PREEMPT_LOCK_OFFSET);
    7052           0 :         int ret = 0;
    7053             : 
    7054           0 :         lockdep_assert_held_write(lock);
    7055             : 
    7056           0 :         if (rwlock_needbreak(lock) || resched) {
    7057           0 :                 write_unlock(lock);
    7058           0 :                 if (resched)
    7059           0 :                         preempt_schedule_common();
    7060             :                 else
    7061             :                         cpu_relax();
    7062           0 :                 ret = 1;
    7063           0 :                 write_lock(lock);
    7064             :         }
    7065           0 :         return ret;
    7066             : }
    7067             : EXPORT_SYMBOL(__cond_resched_rwlock_write);
    7068             : 
    7069             : /**
    7070             :  * yield - yield the current processor to other threads.
    7071             :  *
    7072             :  * Do not ever use this function, there's a 99% chance you're doing it wrong.
    7073             :  *
    7074             :  * The scheduler is at all times free to pick the calling task as the most
    7075             :  * eligible task to run, if removing the yield() call from your code breaks
    7076             :  * it, it's already broken.
    7077             :  *
    7078             :  * Typical broken usage is:
    7079             :  *
    7080             :  * while (!event)
    7081             :  *      yield();
    7082             :  *
    7083             :  * where one assumes that yield() will let 'the other' process run that will
    7084             :  * make event true. If the current task is a SCHED_FIFO task that will never
    7085             :  * happen. Never use yield() as a progress guarantee!!
    7086             :  *
    7087             :  * If you want to use yield() to wait for something, use wait_event().
    7088             :  * If you want to use yield() to be 'nice' for others, use cond_resched().
    7089             :  * If you still want to use yield(), do not!
    7090             :  */
    7091           0 : void __sched yield(void)
    7092             : {
    7093           0 :         set_current_state(TASK_RUNNING);
    7094           0 :         do_sched_yield();
    7095           0 : }
    7096             : EXPORT_SYMBOL(yield);
    7097             : 
    7098             : /**
    7099             :  * yield_to - yield the current processor to another thread in
    7100             :  * your thread group, or accelerate that thread toward the
    7101             :  * processor it's on.
    7102             :  * @p: target task
    7103             :  * @preempt: whether task preemption is allowed or not
    7104             :  *
    7105             :  * It's the caller's job to ensure that the target task struct
    7106             :  * can't go away on us before we can do any checks.
    7107             :  *
    7108             :  * Return:
    7109             :  *      true (>0) if we indeed boosted the target task.
    7110             :  *      false (0) if we failed to boost the target.
    7111             :  *      -ESRCH if there's no task to yield to.
    7112             :  */
    7113           0 : int __sched yield_to(struct task_struct *p, bool preempt)
    7114             : {
    7115           0 :         struct task_struct *curr = current;
    7116           0 :         struct rq *rq, *p_rq;
    7117           0 :         unsigned long flags;
    7118           0 :         int yielded = 0;
    7119             : 
    7120           0 :         local_irq_save(flags);
    7121           0 :         rq = this_rq();
    7122             : 
    7123           0 : again:
    7124           0 :         p_rq = task_rq(p);
    7125             :         /*
    7126             :          * If we're the only runnable task on the rq and target rq also
    7127             :          * has only one task, there's absolutely no point in yielding.
    7128             :          */
    7129           0 :         if (rq->nr_running == 1 && p_rq->nr_running == 1) {
    7130           0 :                 yielded = -ESRCH;
    7131           0 :                 goto out_irq;
    7132             :         }
    7133             : 
    7134           0 :         double_rq_lock(rq, p_rq);
    7135           0 :         if (task_rq(p) != p_rq) {
    7136           0 :                 double_rq_unlock(rq, p_rq);
    7137           0 :                 goto again;
    7138             :         }
    7139             : 
    7140           0 :         if (!curr->sched_class->yield_to_task)
    7141           0 :                 goto out_unlock;
    7142             : 
    7143           0 :         if (curr->sched_class != p->sched_class)
    7144           0 :                 goto out_unlock;
    7145             : 
    7146           0 :         if (task_running(p_rq, p) || p->state)
    7147           0 :                 goto out_unlock;
    7148             : 
    7149           0 :         yielded = curr->sched_class->yield_to_task(rq, p);
    7150           0 :         if (yielded) {
    7151           0 :                 schedstat_inc(rq->yld_count);
    7152             :                 /*
    7153             :                  * Make p's CPU reschedule; pick_next_entity takes care of
    7154             :                  * fairness.
    7155             :                  */
    7156           0 :                 if (preempt && rq != p_rq)
    7157           0 :                         resched_curr(p_rq);
    7158             :         }
    7159             : 
    7160           0 : out_unlock:
    7161           0 :         double_rq_unlock(rq, p_rq);
    7162           0 : out_irq:
    7163           0 :         local_irq_restore(flags);
    7164             : 
    7165           0 :         if (yielded > 0)
    7166           0 :                 schedule();
    7167             : 
    7168           0 :         return yielded;
    7169             : }
    7170             : EXPORT_SYMBOL_GPL(yield_to);
    7171             : 
    7172        1875 : int io_schedule_prepare(void)
    7173             : {
    7174        1875 :         int old_iowait = current->in_iowait;
    7175             : 
    7176        1875 :         current->in_iowait = 1;
    7177        1875 :         blk_schedule_flush_plug(current);
    7178             : 
    7179        1875 :         return old_iowait;
    7180             : }
    7181             : 
    7182        1875 : void io_schedule_finish(int token)
    7183             : {
    7184        1875 :         current->in_iowait = token;
    7185           1 : }
    7186             : 
    7187             : /*
    7188             :  * This task is about to go to sleep on IO. Increment rq->nr_iowait so
    7189             :  * that process accounting knows that this is a task in IO wait state.
    7190             :  */
    7191          74 : long __sched io_schedule_timeout(long timeout)
    7192             : {
    7193          74 :         int token;
    7194          74 :         long ret;
    7195             : 
    7196          74 :         token = io_schedule_prepare();
    7197          74 :         ret = schedule_timeout(timeout);
    7198          74 :         io_schedule_finish(token);
    7199             : 
    7200          74 :         return ret;
    7201             : }
    7202             : EXPORT_SYMBOL(io_schedule_timeout);
    7203             : 
    7204        1800 : void __sched io_schedule(void)
    7205             : {
    7206        1800 :         int token;
    7207             : 
    7208        1800 :         token = io_schedule_prepare();
    7209        1800 :         schedule();
    7210        1800 :         io_schedule_finish(token);
    7211        1800 : }
    7212             : EXPORT_SYMBOL(io_schedule);
    7213             : 
    7214             : /**
    7215             :  * sys_sched_get_priority_max - return maximum RT priority.
    7216             :  * @policy: scheduling class.
    7217             :  *
    7218             :  * Return: On success, this syscall returns the maximum
    7219             :  * rt_priority that can be used by a given scheduling class.
    7220             :  * On failure, a negative error code is returned.
    7221             :  */
    7222           4 : SYSCALL_DEFINE1(sched_get_priority_max, int, policy)
    7223             : {
    7224           2 :         int ret = -EINVAL;
    7225             : 
    7226           2 :         switch (policy) {
    7227           0 :         case SCHED_FIFO:
    7228             :         case SCHED_RR:
    7229           0 :                 ret = MAX_RT_PRIO-1;
    7230           0 :                 break;
    7231           2 :         case SCHED_DEADLINE:
    7232             :         case SCHED_NORMAL:
    7233             :         case SCHED_BATCH:
    7234             :         case SCHED_IDLE:
    7235           2 :                 ret = 0;
    7236           2 :                 break;
    7237             :         }
    7238           2 :         return ret;
    7239             : }
    7240             : 
    7241             : /**
    7242             :  * sys_sched_get_priority_min - return minimum RT priority.
    7243             :  * @policy: scheduling class.
    7244             :  *
    7245             :  * Return: On success, this syscall returns the minimum
    7246             :  * rt_priority that can be used by a given scheduling class.
    7247             :  * On failure, a negative error code is returned.
    7248             :  */
    7249           4 : SYSCALL_DEFINE1(sched_get_priority_min, int, policy)
    7250             : {
    7251           2 :         int ret = -EINVAL;
    7252             : 
    7253           2 :         switch (policy) {
    7254           0 :         case SCHED_FIFO:
    7255             :         case SCHED_RR:
    7256           0 :                 ret = 1;
    7257           0 :                 break;
    7258           2 :         case SCHED_DEADLINE:
    7259             :         case SCHED_NORMAL:
    7260             :         case SCHED_BATCH:
    7261             :         case SCHED_IDLE:
    7262           2 :                 ret = 0;
    7263             :         }
    7264           2 :         return ret;
    7265             : }
    7266             : 
    7267           0 : static int sched_rr_get_interval(pid_t pid, struct timespec64 *t)
    7268             : {
    7269           0 :         struct task_struct *p;
    7270           0 :         unsigned int time_slice;
    7271           0 :         struct rq_flags rf;
    7272           0 :         struct rq *rq;
    7273           0 :         int retval;
    7274             : 
    7275           0 :         if (pid < 0)
    7276             :                 return -EINVAL;
    7277             : 
    7278           0 :         retval = -ESRCH;
    7279           0 :         rcu_read_lock();
    7280           0 :         p = find_process_by_pid(pid);
    7281           0 :         if (!p)
    7282           0 :                 goto out_unlock;
    7283             : 
    7284           0 :         retval = security_task_getscheduler(p);
    7285           0 :         if (retval)
    7286           0 :                 goto out_unlock;
    7287             : 
    7288           0 :         rq = task_rq_lock(p, &rf);
    7289           0 :         time_slice = 0;
    7290           0 :         if (p->sched_class->get_rr_interval)
    7291           0 :                 time_slice = p->sched_class->get_rr_interval(rq, p);
    7292           0 :         task_rq_unlock(rq, p, &rf);
    7293             : 
    7294           0 :         rcu_read_unlock();
    7295           0 :         jiffies_to_timespec64(time_slice, t);
    7296           0 :         return 0;
    7297             : 
    7298           0 : out_unlock:
    7299           0 :         rcu_read_unlock();
    7300           0 :         return retval;
    7301             : }
    7302             : 
    7303             : /**
    7304             :  * sys_sched_rr_get_interval - return the default timeslice of a process.
    7305             :  * @pid: pid of the process.
    7306             :  * @interval: userspace pointer to the timeslice value.
    7307             :  *
    7308             :  * this syscall writes the default timeslice value of a given process
    7309             :  * into the user-space timespec buffer. A value of '0' means infinity.
    7310             :  *
    7311             :  * Return: On success, 0 and the timeslice is in @interval. Otherwise,
    7312             :  * an error code.
    7313             :  */
    7314           0 : SYSCALL_DEFINE2(sched_rr_get_interval, pid_t, pid,
    7315             :                 struct __kernel_timespec __user *, interval)
    7316             : {
    7317           0 :         struct timespec64 t;
    7318           0 :         int retval = sched_rr_get_interval(pid, &t);
    7319             : 
    7320           0 :         if (retval == 0)
    7321           0 :                 retval = put_timespec64(&t, interval);
    7322             : 
    7323           0 :         return retval;
    7324             : }
    7325             : 
    7326             : #ifdef CONFIG_COMPAT_32BIT_TIME
    7327             : SYSCALL_DEFINE2(sched_rr_get_interval_time32, pid_t, pid,
    7328             :                 struct old_timespec32 __user *, interval)
    7329             : {
    7330             :         struct timespec64 t;
    7331             :         int retval = sched_rr_get_interval(pid, &t);
    7332             : 
    7333             :         if (retval == 0)
    7334             :                 retval = put_old_timespec32(&t, interval);
    7335             :         return retval;
    7336             : }
    7337             : #endif
    7338             : 
    7339           0 : void sched_show_task(struct task_struct *p)
    7340             : {
    7341           0 :         unsigned long free = 0;
    7342           0 :         int ppid;
    7343             : 
    7344           0 :         if (!try_get_task_stack(p))
    7345             :                 return;
    7346             : 
    7347           0 :         pr_info("task:%-15.15s state:%c", p->comm, task_state_to_char(p));
    7348             : 
    7349           0 :         if (p->state == TASK_RUNNING)
    7350           0 :                 pr_cont("  running task    ");
    7351             : #ifdef CONFIG_DEBUG_STACK_USAGE
    7352             :         free = stack_not_used(p);
    7353             : #endif
    7354           0 :         ppid = 0;
    7355           0 :         rcu_read_lock();
    7356           0 :         if (pid_alive(p))
    7357           0 :                 ppid = task_pid_nr(rcu_dereference(p->real_parent));
    7358           0 :         rcu_read_unlock();
    7359           0 :         pr_cont(" stack:%5lu pid:%5d ppid:%6d flags:0x%08lx\n",
    7360             :                 free, task_pid_nr(p), ppid,
    7361             :                 (unsigned long)task_thread_info(p)->flags);
    7362             : 
    7363           0 :         print_worker_info(KERN_INFO, p);
    7364           0 :         print_stop_info(KERN_INFO, p);
    7365           0 :         show_stack(p, NULL, KERN_INFO);
    7366           0 :         put_task_stack(p);
    7367             : }
    7368             : EXPORT_SYMBOL_GPL(sched_show_task);
    7369             : 
    7370             : static inline bool
    7371           0 : state_filter_match(unsigned long state_filter, struct task_struct *p)
    7372             : {
    7373             :         /* no filter, everything matches */
    7374           0 :         if (!state_filter)
    7375             :                 return true;
    7376             : 
    7377             :         /* filter, but doesn't match */
    7378           0 :         if (!(p->state & state_filter))
    7379             :                 return false;
    7380             : 
    7381             :         /*
    7382             :          * When looking for TASK_UNINTERRUPTIBLE skip TASK_IDLE (allows
    7383             :          * TASK_KILLABLE).
    7384             :          */
    7385           0 :         if (state_filter == TASK_UNINTERRUPTIBLE && p->state == TASK_IDLE)
    7386             :                 return false;
    7387             : 
    7388             :         return true;
    7389             : }
    7390             : 
    7391             : 
    7392           0 : void show_state_filter(unsigned long state_filter)
    7393             : {
    7394           0 :         struct task_struct *g, *p;
    7395             : 
    7396           0 :         rcu_read_lock();
    7397           0 :         for_each_process_thread(g, p) {
    7398             :                 /*
    7399             :                  * reset the NMI-timeout, listing all files on a slow
    7400             :                  * console might take a lot of time:
    7401             :                  * Also, reset softlockup watchdogs on all CPUs, because
    7402             :                  * another CPU might be blocked waiting for us to process
    7403             :                  * an IPI.
    7404             :                  */
    7405           0 :                 touch_nmi_watchdog();
    7406           0 :                 touch_all_softlockup_watchdogs();
    7407           0 :                 if (state_filter_match(state_filter, p))
    7408           0 :                         sched_show_task(p);
    7409             :         }
    7410             : 
    7411             : #ifdef CONFIG_SCHED_DEBUG
    7412             :         if (!state_filter)
    7413             :                 sysrq_sched_debug_show();
    7414             : #endif
    7415           0 :         rcu_read_unlock();
    7416             :         /*
    7417             :          * Only show locks if all tasks are dumped:
    7418             :          */
    7419           0 :         if (!state_filter)
    7420           0 :                 debug_show_all_locks();
    7421           0 : }
    7422             : 
    7423             : /**
    7424             :  * init_idle - set up an idle thread for a given CPU
    7425             :  * @idle: task in question
    7426             :  * @cpu: CPU the idle task belongs to
    7427             :  *
    7428             :  * NOTE: this function does not set the idle thread's NEED_RESCHED
    7429             :  * flag, to make booting more robust.
    7430             :  */
    7431          10 : void init_idle(struct task_struct *idle, int cpu)
    7432             : {
    7433          10 :         struct rq *rq = cpu_rq(cpu);
    7434          10 :         unsigned long flags;
    7435             : 
    7436          10 :         __sched_fork(0, idle);
    7437             : 
    7438          10 :         raw_spin_lock_irqsave(&idle->pi_lock, flags);
    7439          10 :         raw_spin_lock(&rq->lock);
    7440             : 
    7441          10 :         idle->state = TASK_RUNNING;
    7442          10 :         idle->se.exec_start = sched_clock();
    7443          10 :         idle->flags |= PF_IDLE;
    7444             : 
    7445          10 :         scs_task_reset(idle);
    7446          10 :         kasan_unpoison_task_stack(idle);
    7447             : 
    7448             : #ifdef CONFIG_SMP
    7449             :         /*
    7450             :          * It's possible that init_idle() gets called multiple times on a task,
    7451             :          * in that case do_set_cpus_allowed() will not do the right thing.
    7452             :          *
    7453             :          * And since this is boot we can forgo the serialization.
    7454             :          */
    7455          10 :         set_cpus_allowed_common(idle, cpumask_of(cpu), 0);
    7456             : #endif
    7457             :         /*
    7458             :          * We're having a chicken and egg problem, even though we are
    7459             :          * holding rq->lock, the CPU isn't yet set to this CPU so the
    7460             :          * lockdep check in task_group() will fail.
    7461             :          *
    7462             :          * Similar case to sched_fork(). / Alternatively we could
    7463             :          * use task_rq_lock() here and obtain the other rq->lock.
    7464             :          *
    7465             :          * Silence PROVE_RCU
    7466             :          */
    7467          10 :         rcu_read_lock();
    7468          10 :         __set_task_cpu(idle, cpu);
    7469          10 :         rcu_read_unlock();
    7470             : 
    7471          10 :         rq->idle = idle;
    7472          10 :         rcu_assign_pointer(rq->curr, idle);
    7473          10 :         idle->on_rq = TASK_ON_RQ_QUEUED;
    7474             : #ifdef CONFIG_SMP
    7475          10 :         idle->on_cpu = 1;
    7476             : #endif
    7477          10 :         raw_spin_unlock(&rq->lock);
    7478          10 :         raw_spin_unlock_irqrestore(&idle->pi_lock, flags);
    7479             : 
    7480             :         /* Set the preempt count _outside_ the spinlocks! */
    7481          10 :         init_idle_preempt_count(idle, cpu);
    7482             : 
    7483             :         /*
    7484             :          * The idle tasks have their own, simple scheduling class:
    7485             :          */
    7486          10 :         idle->sched_class = &idle_sched_class;
    7487          10 :         ftrace_graph_init_idle_task(idle, cpu);
    7488          10 :         vtime_init_idle(idle, cpu);
    7489             : #ifdef CONFIG_SMP
    7490          10 :         sprintf(idle->comm, "%s/%d", INIT_TASK_COMM, cpu);
    7491             : #endif
    7492          10 : }
    7493             : 
    7494             : #ifdef CONFIG_SMP
    7495             : 
    7496           0 : int cpuset_cpumask_can_shrink(const struct cpumask *cur,
    7497             :                               const struct cpumask *trial)
    7498             : {
    7499           0 :         int ret = 1;
    7500             : 
    7501           0 :         if (!cpumask_weight(cur))
    7502             :                 return ret;
    7503             : 
    7504           0 :         ret = dl_cpuset_cpumask_can_shrink(cur, trial);
    7505             : 
    7506           0 :         return ret;
    7507             : }
    7508             : 
    7509           0 : int task_can_attach(struct task_struct *p,
    7510             :                     const struct cpumask *cs_cpus_allowed)
    7511             : {
    7512           0 :         int ret = 0;
    7513             : 
    7514             :         /*
    7515             :          * Kthreads which disallow setaffinity shouldn't be moved
    7516             :          * to a new cpuset; we don't want to change their CPU
    7517             :          * affinity and isolating such threads by their set of
    7518             :          * allowed nodes is unnecessary.  Thus, cpusets are not
    7519             :          * applicable for such threads.  This prevents checking for
    7520             :          * success of set_cpus_allowed_ptr() on all attached tasks
    7521             :          * before cpus_mask may be changed.
    7522             :          */
    7523           0 :         if (p->flags & PF_NO_SETAFFINITY) {
    7524           0 :                 ret = -EINVAL;
    7525           0 :                 goto out;
    7526             :         }
    7527             : 
    7528           0 :         if (dl_task(p) && !cpumask_intersects(task_rq(p)->rd->span,
    7529             :                                               cs_cpus_allowed))
    7530           0 :                 ret = dl_task_can_attach(p, cs_cpus_allowed);
    7531             : 
    7532           0 : out:
    7533           0 :         return ret;
    7534             : }
    7535             : 
    7536             : bool sched_smp_initialized __read_mostly;
    7537             : 
    7538             : #ifdef CONFIG_NUMA_BALANCING
    7539             : /* Migrate current task p to target_cpu */
    7540             : int migrate_task_to(struct task_struct *p, int target_cpu)
    7541             : {
    7542             :         struct migration_arg arg = { p, target_cpu };
    7543             :         int curr_cpu = task_cpu(p);
    7544             : 
    7545             :         if (curr_cpu == target_cpu)
    7546             :                 return 0;
    7547             : 
    7548             :         if (!cpumask_test_cpu(target_cpu, p->cpus_ptr))
    7549             :                 return -EINVAL;
    7550             : 
    7551             :         /* TODO: This is not properly updating schedstats */
    7552             : 
    7553             :         trace_sched_move_numa(p, curr_cpu, target_cpu);
    7554             :         return stop_one_cpu(curr_cpu, migration_cpu_stop, &arg);
    7555             : }
    7556             : 
    7557             : /*
    7558             :  * Requeue a task on a given node and accurately track the number of NUMA
    7559             :  * tasks on the runqueues
    7560             :  */
    7561             : void sched_setnuma(struct task_struct *p, int nid)
    7562             : {
    7563             :         bool queued, running;
    7564             :         struct rq_flags rf;
    7565             :         struct rq *rq;
    7566             : 
    7567             :         rq = task_rq_lock(p, &rf);
    7568             :         queued = task_on_rq_queued(p);
    7569             :         running = task_current(rq, p);
    7570             : 
    7571             :         if (queued)
    7572             :                 dequeue_task(rq, p, DEQUEUE_SAVE);
    7573             :         if (running)
    7574             :                 put_prev_task(rq, p);
    7575             : 
    7576             :         p->numa_preferred_nid = nid;
    7577             : 
    7578             :         if (queued)
    7579             :                 enqueue_task(rq, p, ENQUEUE_RESTORE | ENQUEUE_NOCLOCK);
    7580             :         if (running)
    7581             :                 set_next_task(rq, p);
    7582             :         task_rq_unlock(rq, p, &rf);
    7583             : }
    7584             : #endif /* CONFIG_NUMA_BALANCING */
    7585             : 
    7586             : #ifdef CONFIG_HOTPLUG_CPU
    7587             : /*
    7588             :  * Ensure that the idle task is using init_mm right before its CPU goes
    7589             :  * offline.
    7590             :  */
    7591           0 : void idle_task_exit(void)
    7592             : {
    7593           0 :         struct mm_struct *mm = current->active_mm;
    7594             : 
    7595           0 :         BUG_ON(cpu_online(smp_processor_id()));
    7596           0 :         BUG_ON(current != this_rq()->idle);
    7597             : 
    7598           0 :         if (mm != &init_mm) {
    7599           0 :                 switch_mm(mm, &init_mm, current);
    7600           0 :                 finish_arch_post_lock_switch();
    7601             :         }
    7602             : 
    7603             :         /* finish_cpu(), as ran on the BP, will clean up the active_mm state */
    7604           0 : }
    7605             : 
    7606           0 : static int __balance_push_cpu_stop(void *arg)
    7607             : {
    7608           0 :         struct task_struct *p = arg;
    7609           0 :         struct rq *rq = this_rq();
    7610           0 :         struct rq_flags rf;
    7611           0 :         int cpu;
    7612             : 
    7613           0 :         raw_spin_lock_irq(&p->pi_lock);
    7614           0 :         rq_lock(rq, &rf);
    7615             : 
    7616           0 :         update_rq_clock(rq);
    7617             : 
    7618           0 :         if (task_rq(p) == rq && task_on_rq_queued(p)) {
    7619           0 :                 cpu = select_fallback_rq(rq->cpu, p);
    7620           0 :                 rq = __migrate_task(rq, &rf, p, cpu);
    7621             :         }
    7622             : 
    7623           0 :         rq_unlock(rq, &rf);
    7624           0 :         raw_spin_unlock_irq(&p->pi_lock);
    7625             : 
    7626           0 :         put_task_struct(p);
    7627             : 
    7628           0 :         return 0;
    7629             : }
    7630             : 
    7631             : static DEFINE_PER_CPU(struct cpu_stop_work, push_work);
    7632             : 
    7633             : /*
    7634             :  * Ensure we only run per-cpu kthreads once the CPU goes !active.
    7635             :  */
    7636           0 : static void balance_push(struct rq *rq)
    7637             : {
    7638           0 :         struct task_struct *push_task = rq->curr;
    7639             : 
    7640           0 :         lockdep_assert_held(&rq->lock);
    7641           0 :         SCHED_WARN_ON(rq->cpu != smp_processor_id());
    7642             :         /*
    7643             :          * Ensure the thing is persistent until balance_push_set(.on = false);
    7644             :          */
    7645           0 :         rq->balance_callback = &balance_push_callback;
    7646             : 
    7647             :         /*
    7648             :          * Both the cpu-hotplug and stop task are in this case and are
    7649             :          * required to complete the hotplug process.
    7650             :          *
    7651             :          * XXX: the idle task does not match kthread_is_per_cpu() due to
    7652             :          * histerical raisins.
    7653             :          */
    7654           0 :         if (rq->idle == push_task ||
    7655           0 :             ((push_task->flags & PF_KTHREAD) && kthread_is_per_cpu(push_task)) ||
    7656           0 :             is_migration_disabled(push_task)) {
    7657             : 
    7658             :                 /*
    7659             :                  * If this is the idle task on the outgoing CPU try to wake
    7660             :                  * up the hotplug control thread which might wait for the
    7661             :                  * last task to vanish. The rcuwait_active() check is
    7662             :                  * accurate here because the waiter is pinned on this CPU
    7663             :                  * and can't obviously be running in parallel.
    7664             :                  *
    7665             :                  * On RT kernels this also has to check whether there are
    7666             :                  * pinned and scheduled out tasks on the runqueue. They
    7667             :                  * need to leave the migrate disabled section first.
    7668             :                  */
    7669           0 :                 if (!rq->nr_running && !rq_has_pinned_tasks(rq) &&
    7670           0 :                     rcuwait_active(&rq->hotplug_wait)) {
    7671           0 :                         raw_spin_unlock(&rq->lock);
    7672           0 :                         rcuwait_wake_up(&rq->hotplug_wait);
    7673           0 :                         raw_spin_lock(&rq->lock);
    7674             :                 }
    7675           0 :                 return;
    7676             :         }
    7677             : 
    7678           0 :         get_task_struct(push_task);
    7679             :         /*
    7680             :          * Temporarily drop rq->lock such that we can wake-up the stop task.
    7681             :          * Both preemption and IRQs are still disabled.
    7682             :          */
    7683           0 :         raw_spin_unlock(&rq->lock);
    7684           0 :         stop_one_cpu_nowait(rq->cpu, __balance_push_cpu_stop, push_task,
    7685           0 :                             this_cpu_ptr(&push_work));
    7686             :         /*
    7687             :          * At this point need_resched() is true and we'll take the loop in
    7688             :          * schedule(). The next pick is obviously going to be the stop task
    7689             :          * which kthread_is_per_cpu() and will push this task away.
    7690             :          */
    7691           0 :         raw_spin_lock(&rq->lock);
    7692             : }
    7693             : 
    7694           3 : static void balance_push_set(int cpu, bool on)
    7695             : {
    7696           3 :         struct rq *rq = cpu_rq(cpu);
    7697           3 :         struct rq_flags rf;
    7698             : 
    7699           3 :         rq_lock_irqsave(rq, &rf);
    7700           3 :         rq->balance_push = on;
    7701           3 :         if (on) {
    7702           0 :                 WARN_ON_ONCE(rq->balance_callback);
    7703           0 :                 rq->balance_callback = &balance_push_callback;
    7704           3 :         } else if (rq->balance_callback == &balance_push_callback) {
    7705           0 :                 rq->balance_callback = NULL;
    7706             :         }
    7707           3 :         rq_unlock_irqrestore(rq, &rf);
    7708           3 : }
    7709             : 
    7710             : /*
    7711             :  * Invoked from a CPUs hotplug control thread after the CPU has been marked
    7712             :  * inactive. All tasks which are not per CPU kernel threads are either
    7713             :  * pushed off this CPU now via balance_push() or placed on a different CPU
    7714             :  * during wakeup. Wait until the CPU is quiescent.
    7715             :  */
    7716           0 : static void balance_hotplug_wait(void)
    7717             : {
    7718           0 :         struct rq *rq = this_rq();
    7719             : 
    7720           0 :         rcuwait_wait_event(&rq->hotplug_wait,
    7721             :                            rq->nr_running == 1 && !rq_has_pinned_tasks(rq),
    7722             :                            TASK_UNINTERRUPTIBLE);
    7723           0 : }
    7724             : 
    7725             : #else
    7726             : 
    7727             : static inline void balance_push(struct rq *rq)
    7728             : {
    7729             : }
    7730             : 
    7731             : static inline void balance_push_set(int cpu, bool on)
    7732             : {
    7733             : }
    7734             : 
    7735             : static inline void balance_hotplug_wait(void)
    7736             : {
    7737             : }
    7738             : 
    7739             : #endif /* CONFIG_HOTPLUG_CPU */
    7740             : 
    7741           8 : void set_rq_online(struct rq *rq)
    7742             : {
    7743           8 :         if (!rq->online) {
    7744           8 :                 const struct sched_class *class;
    7745             : 
    7746           8 :                 cpumask_set_cpu(rq->cpu, rq->rd->online);
    7747           8 :                 rq->online = 1;
    7748             : 
    7749          48 :                 for_each_class(class) {
    7750          40 :                         if (class->rq_online)
    7751          24 :                                 class->rq_online(rq);
    7752             :                 }
    7753             :         }
    7754           8 : }
    7755             : 
    7756           4 : void set_rq_offline(struct rq *rq)
    7757             : {
    7758           4 :         if (rq->online) {
    7759             :                 const struct sched_class *class;
    7760             : 
    7761          24 :                 for_each_class(class) {
    7762          20 :                         if (class->rq_offline)
    7763          12 :                                 class->rq_offline(rq);
    7764             :                 }
    7765             : 
    7766           4 :                 cpumask_clear_cpu(rq->cpu, rq->rd->online);
    7767           4 :                 rq->online = 0;
    7768             :         }
    7769           4 : }
    7770             : 
    7771             : /*
    7772             :  * used to mark begin/end of suspend/resume:
    7773             :  */
    7774             : static int num_cpus_frozen;
    7775             : 
    7776             : /*
    7777             :  * Update cpusets according to cpu_active mask.  If cpusets are
    7778             :  * disabled, cpuset_update_active_cpus() becomes a simple wrapper
    7779             :  * around partition_sched_domains().
    7780             :  *
    7781             :  * If we come here as part of a suspend/resume, don't touch cpusets because we
    7782             :  * want to restore it back to its original state upon resume anyway.
    7783             :  */
    7784           0 : static void cpuset_cpu_active(void)
    7785             : {
    7786           0 :         if (cpuhp_tasks_frozen) {
    7787             :                 /*
    7788             :                  * num_cpus_frozen tracks how many CPUs are involved in suspend
    7789             :                  * resume sequence. As long as this is not the last online
    7790             :                  * operation in the resume sequence, just build a single sched
    7791             :                  * domain, ignoring cpusets.
    7792             :                  */
    7793           0 :                 partition_sched_domains(1, NULL, NULL);
    7794           0 :                 if (--num_cpus_frozen)
    7795             :                         return;
    7796             :                 /*
    7797             :                  * This is the last CPU online operation. So fall through and
    7798             :                  * restore the original sched domains by considering the
    7799             :                  * cpuset configurations.
    7800             :                  */
    7801             :                 cpuset_force_rebuild();
    7802             :         }
    7803           0 :         cpuset_update_active_cpus();
    7804             : }
    7805             : 
    7806           0 : static int cpuset_cpu_inactive(unsigned int cpu)
    7807             : {
    7808           0 :         if (!cpuhp_tasks_frozen) {
    7809           0 :                 if (dl_cpu_busy(cpu))
    7810             :                         return -EBUSY;
    7811           0 :                 cpuset_update_active_cpus();
    7812             :         } else {
    7813           0 :                 num_cpus_frozen++;
    7814           0 :                 partition_sched_domains(1, NULL, NULL);
    7815             :         }
    7816             :         return 0;
    7817             : }
    7818             : 
    7819           3 : int sched_cpu_activate(unsigned int cpu)
    7820             : {
    7821           3 :         struct rq *rq = cpu_rq(cpu);
    7822           3 :         struct rq_flags rf;
    7823             : 
    7824             :         /*
    7825             :          * Make sure that when the hotplug state machine does a roll-back
    7826             :          * we clear balance_push. Ideally that would happen earlier...
    7827             :          */
    7828           3 :         balance_push_set(cpu, false);
    7829             : 
    7830             : #ifdef CONFIG_SCHED_SMT
    7831             :         /*
    7832             :          * When going up, increment the number of cores with SMT present.
    7833             :          */
    7834           3 :         if (cpumask_weight(cpu_smt_mask(cpu)) == 2)
    7835           0 :                 static_branch_inc_cpuslocked(&sched_smt_present);
    7836             : #endif
    7837           3 :         set_cpu_active(cpu, true);
    7838             : 
    7839           3 :         if (sched_smp_initialized) {
    7840           0 :                 sched_domains_numa_masks_set(cpu);
    7841           0 :                 cpuset_cpu_active();
    7842             :         }
    7843             : 
    7844             :         /*
    7845             :          * Put the rq online, if not already. This happens:
    7846             :          *
    7847             :          * 1) In the early boot process, because we build the real domains
    7848             :          *    after all CPUs have been brought up.
    7849             :          *
    7850             :          * 2) At runtime, if cpuset_cpu_active() fails to rebuild the
    7851             :          *    domains.
    7852             :          */
    7853           3 :         rq_lock_irqsave(rq, &rf);
    7854           3 :         if (rq->rd) {
    7855           3 :                 BUG_ON(!cpumask_test_cpu(cpu, rq->rd->span));
    7856           3 :                 set_rq_online(rq);
    7857             :         }
    7858           3 :         rq_unlock_irqrestore(rq, &rf);
    7859             : 
    7860           3 :         return 0;
    7861             : }
    7862             : 
    7863           0 : int sched_cpu_deactivate(unsigned int cpu)
    7864             : {
    7865           0 :         struct rq *rq = cpu_rq(cpu);
    7866           0 :         struct rq_flags rf;
    7867           0 :         int ret;
    7868             : 
    7869             :         /*
    7870             :          * Remove CPU from nohz.idle_cpus_mask to prevent participating in
    7871             :          * load balancing when not active
    7872             :          */
    7873           0 :         nohz_balance_exit_idle(rq);
    7874             : 
    7875           0 :         set_cpu_active(cpu, false);
    7876             : 
    7877             :         /*
    7878             :          * From this point forward, this CPU will refuse to run any task that
    7879             :          * is not: migrate_disable() or KTHREAD_IS_PER_CPU, and will actively
    7880             :          * push those tasks away until this gets cleared, see
    7881             :          * sched_cpu_dying().
    7882             :          */
    7883           0 :         balance_push_set(cpu, true);
    7884             : 
    7885             :         /*
    7886             :          * We've cleared cpu_active_mask / set balance_push, wait for all
    7887             :          * preempt-disabled and RCU users of this state to go away such that
    7888             :          * all new such users will observe it.
    7889             :          *
    7890             :          * Specifically, we rely on ttwu to no longer target this CPU, see
    7891             :          * ttwu_queue_cond() and is_cpu_allowed().
    7892             :          *
    7893             :          * Do sync before park smpboot threads to take care the rcu boost case.
    7894             :          */
    7895           0 :         synchronize_rcu();
    7896             : 
    7897           0 :         rq_lock_irqsave(rq, &rf);
    7898           0 :         if (rq->rd) {
    7899           0 :                 update_rq_clock(rq);
    7900           0 :                 BUG_ON(!cpumask_test_cpu(cpu, rq->rd->span));
    7901           0 :                 set_rq_offline(rq);
    7902             :         }
    7903           0 :         rq_unlock_irqrestore(rq, &rf);
    7904             : 
    7905             : #ifdef CONFIG_SCHED_SMT
    7906             :         /*
    7907             :          * When going down, decrement the number of cores with SMT present.
    7908             :          */
    7909           0 :         if (cpumask_weight(cpu_smt_mask(cpu)) == 2)
    7910           0 :                 static_branch_dec_cpuslocked(&sched_smt_present);
    7911             : #endif
    7912             : 
    7913           0 :         if (!sched_smp_initialized)
    7914             :                 return 0;
    7915             : 
    7916           0 :         ret = cpuset_cpu_inactive(cpu);
    7917           0 :         if (ret) {
    7918           0 :                 balance_push_set(cpu, false);
    7919           0 :                 set_cpu_active(cpu, true);
    7920           0 :                 return ret;
    7921             :         }
    7922           0 :         sched_domains_numa_masks_clear(cpu);
    7923           0 :         return 0;
    7924             : }
    7925             : 
    7926           4 : static void sched_rq_cpu_starting(unsigned int cpu)
    7927             : {
    7928           4 :         struct rq *rq = cpu_rq(cpu);
    7929             : 
    7930           4 :         rq->calc_load_update = calc_load_update;
    7931           4 :         update_max_interval();
    7932           4 : }
    7933             : 
    7934           4 : int sched_cpu_starting(unsigned int cpu)
    7935             : {
    7936           4 :         sched_rq_cpu_starting(cpu);
    7937           4 :         sched_tick_start(cpu);
    7938           4 :         return 0;
    7939             : }
    7940             : 
    7941             : #ifdef CONFIG_HOTPLUG_CPU
    7942             : 
    7943             : /*
    7944             :  * Invoked immediately before the stopper thread is invoked to bring the
    7945             :  * CPU down completely. At this point all per CPU kthreads except the
    7946             :  * hotplug thread (current) and the stopper thread (inactive) have been
    7947             :  * either parked or have been unbound from the outgoing CPU. Ensure that
    7948             :  * any of those which might be on the way out are gone.
    7949             :  *
    7950             :  * If after this point a bound task is being woken on this CPU then the
    7951             :  * responsible hotplug callback has failed to do it's job.
    7952             :  * sched_cpu_dying() will catch it with the appropriate fireworks.
    7953             :  */
    7954           0 : int sched_cpu_wait_empty(unsigned int cpu)
    7955             : {
    7956           0 :         balance_hotplug_wait();
    7957           0 :         return 0;
    7958             : }
    7959             : 
    7960             : /*
    7961             :  * Since this CPU is going 'away' for a while, fold any nr_active delta we
    7962             :  * might have. Called from the CPU stopper task after ensuring that the
    7963             :  * stopper is the last running task on the CPU, so nr_active count is
    7964             :  * stable. We need to take the teardown thread which is calling this into
    7965             :  * account, so we hand in adjust = 1 to the load calculation.
    7966             :  *
    7967             :  * Also see the comment "Global load-average calculations".
    7968             :  */
    7969           0 : static void calc_load_migrate(struct rq *rq)
    7970             : {
    7971           0 :         long delta = calc_load_fold_active(rq, 1);
    7972             : 
    7973           0 :         if (delta)
    7974           0 :                 atomic_long_add(delta, &calc_load_tasks);
    7975           0 : }
    7976             : 
    7977           0 : static void dump_rq_tasks(struct rq *rq, const char *loglvl)
    7978             : {
    7979           0 :         struct task_struct *g, *p;
    7980           0 :         int cpu = cpu_of(rq);
    7981             : 
    7982           0 :         lockdep_assert_held(&rq->lock);
    7983             : 
    7984           0 :         printk("%sCPU%d enqueued tasks (%u total):\n", loglvl, cpu, rq->nr_running);
    7985           0 :         for_each_process_thread(g, p) {
    7986           0 :                 if (task_cpu(p) != cpu)
    7987           0 :                         continue;
    7988             : 
    7989           0 :                 if (!task_on_rq_queued(p))
    7990           0 :                         continue;
    7991             : 
    7992           0 :                 printk("%s\tpid: %d, name: %s\n", loglvl, p->pid, p->comm);
    7993             :         }
    7994           0 : }
    7995             : 
    7996           0 : int sched_cpu_dying(unsigned int cpu)
    7997             : {
    7998           0 :         struct rq *rq = cpu_rq(cpu);
    7999           0 :         struct rq_flags rf;
    8000             : 
    8001             :         /* Handle pending wakeups and then migrate everything off */
    8002           0 :         sched_tick_stop(cpu);
    8003             : 
    8004           0 :         rq_lock_irqsave(rq, &rf);
    8005           0 :         if (rq->nr_running != 1 || rq_has_pinned_tasks(rq)) {
    8006           0 :                 WARN(true, "Dying CPU not properly vacated!");
    8007           0 :                 dump_rq_tasks(rq, KERN_WARNING);
    8008             :         }
    8009           0 :         rq_unlock_irqrestore(rq, &rf);
    8010             : 
    8011             :         /*
    8012             :          * Now that the CPU is offline, make sure we're welcome
    8013             :          * to new tasks once we come back up.
    8014             :          */
    8015           0 :         balance_push_set(cpu, false);
    8016             : 
    8017           0 :         calc_load_migrate(rq);
    8018           0 :         update_max_interval();
    8019           0 :         hrtick_clear(rq);
    8020           0 :         return 0;
    8021             : }
    8022             : #endif
    8023             : 
    8024           1 : void __init sched_init_smp(void)
    8025             : {
    8026           1 :         sched_init_numa();
    8027             : 
    8028             :         /*
    8029             :          * There's no userspace yet to cause hotplug operations; hence all the
    8030             :          * CPU masks are stable and all blatant races in the below code cannot
    8031             :          * happen.
    8032             :          */
    8033           1 :         mutex_lock(&sched_domains_mutex);
    8034           1 :         sched_init_domains(cpu_active_mask);
    8035           1 :         mutex_unlock(&sched_domains_mutex);
    8036             : 
    8037             :         /* Move init over to a non-isolated CPU */
    8038           1 :         if (set_cpus_allowed_ptr(current, housekeeping_cpumask(HK_FLAG_DOMAIN)) < 0)
    8039           0 :                 BUG();
    8040           1 :         sched_init_granularity();
    8041             : 
    8042           1 :         init_sched_rt_class();
    8043           1 :         init_sched_dl_class();
    8044             : 
    8045           1 :         sched_smp_initialized = true;
    8046           1 : }
    8047             : 
    8048           1 : static int __init migration_init(void)
    8049             : {
    8050           1 :         sched_cpu_starting(smp_processor_id());
    8051           1 :         return 0;
    8052             : }
    8053             : early_initcall(migration_init);
    8054             : 
    8055             : #else
    8056             : void __init sched_init_smp(void)
    8057             : {
    8058             :         sched_init_granularity();
    8059             : }
    8060             : #endif /* CONFIG_SMP */
    8061             : 
    8062         117 : int in_sched_functions(unsigned long addr)
    8063             : {
    8064         117 :         return in_lock_functions(addr) ||
    8065         117 :                 (addr >= (unsigned long)__sched_text_start
    8066          65 :                 && addr < (unsigned long)__sched_text_end);
    8067             : }
    8068             : 
    8069             : #ifdef CONFIG_CGROUP_SCHED
    8070             : /*
    8071             :  * Default task group.
    8072             :  * Every task in system belongs to this group at bootup.
    8073             :  */
    8074             : struct task_group root_task_group;
    8075             : LIST_HEAD(task_groups);
    8076             : 
    8077             : /* Cacheline aligned slab cache for task_group */
    8078             : static struct kmem_cache *task_group_cache __read_mostly;
    8079             : #endif
    8080             : 
    8081             : DECLARE_PER_CPU(cpumask_var_t, load_balance_mask);
    8082             : DECLARE_PER_CPU(cpumask_var_t, select_idle_mask);
    8083             : 
    8084           1 : void __init sched_init(void)
    8085             : {
    8086           1 :         unsigned long ptr = 0;
    8087           1 :         int i;
    8088             : 
    8089             :         /* Make sure the linker didn't screw up */
    8090           1 :         BUG_ON(&idle_sched_class + 1 != &fair_sched_class ||
    8091             :                &fair_sched_class + 1 != &rt_sched_class ||
    8092             :                &rt_sched_class + 1   != &dl_sched_class);
    8093             : #ifdef CONFIG_SMP
    8094           1 :         BUG_ON(&dl_sched_class + 1 != &stop_sched_class);
    8095             : #endif
    8096             : 
    8097           1 :         wait_bit_init();
    8098             : 
    8099             : #ifdef CONFIG_FAIR_GROUP_SCHED
    8100             :         ptr += 2 * nr_cpu_ids * sizeof(void **);
    8101             : #endif
    8102             : #ifdef CONFIG_RT_GROUP_SCHED
    8103             :         ptr += 2 * nr_cpu_ids * sizeof(void **);
    8104             : #endif
    8105           1 :         if (ptr) {
    8106             :                 ptr = (unsigned long)kzalloc(ptr, GFP_NOWAIT);
    8107             : 
    8108             : #ifdef CONFIG_FAIR_GROUP_SCHED
    8109             :                 root_task_group.se = (struct sched_entity **)ptr;
    8110             :                 ptr += nr_cpu_ids * sizeof(void **);
    8111             : 
    8112             :                 root_task_group.cfs_rq = (struct cfs_rq **)ptr;
    8113             :                 ptr += nr_cpu_ids * sizeof(void **);
    8114             : 
    8115             :                 root_task_group.shares = ROOT_TASK_GROUP_LOAD;
    8116             :                 init_cfs_bandwidth(&root_task_group.cfs_bandwidth);
    8117             : #endif /* CONFIG_FAIR_GROUP_SCHED */
    8118             : #ifdef CONFIG_RT_GROUP_SCHED
    8119             :                 root_task_group.rt_se = (struct sched_rt_entity **)ptr;
    8120             :                 ptr += nr_cpu_ids * sizeof(void **);
    8121             : 
    8122             :                 root_task_group.rt_rq = (struct rt_rq **)ptr;
    8123             :                 ptr += nr_cpu_ids * sizeof(void **);
    8124             : 
    8125             : #endif /* CONFIG_RT_GROUP_SCHED */
    8126             :         }
    8127             : #ifdef CONFIG_CPUMASK_OFFSTACK
    8128             :         for_each_possible_cpu(i) {
    8129             :                 per_cpu(load_balance_mask, i) = (cpumask_var_t)kzalloc_node(
    8130             :                         cpumask_size(), GFP_KERNEL, cpu_to_node(i));
    8131             :                 per_cpu(select_idle_mask, i) = (cpumask_var_t)kzalloc_node(
    8132             :                         cpumask_size(), GFP_KERNEL, cpu_to_node(i));
    8133             :         }
    8134             : #endif /* CONFIG_CPUMASK_OFFSTACK */
    8135             : 
    8136           2 :         init_rt_bandwidth(&def_rt_bandwidth, global_rt_period(), global_rt_runtime());
    8137           2 :         init_dl_bandwidth(&def_dl_bandwidth, global_rt_period(), global_rt_runtime());
    8138             : 
    8139             : #ifdef CONFIG_SMP
    8140           1 :         init_defrootdomain();
    8141             : #endif
    8142             : 
    8143             : #ifdef CONFIG_RT_GROUP_SCHED
    8144             :         init_rt_bandwidth(&root_task_group.rt_bandwidth,
    8145             :                         global_rt_period(), global_rt_runtime());
    8146             : #endif /* CONFIG_RT_GROUP_SCHED */
    8147             : 
    8148             : #ifdef CONFIG_CGROUP_SCHED
    8149             :         task_group_cache = KMEM_CACHE(task_group, 0);
    8150             : 
    8151             :         list_add(&root_task_group.list, &task_groups);
    8152             :         INIT_LIST_HEAD(&root_task_group.children);
    8153             :         INIT_LIST_HEAD(&root_task_group.siblings);
    8154             :         autogroup_init(&init_task);
    8155             : #endif /* CONFIG_CGROUP_SCHED */
    8156             : 
    8157           6 :         for_each_possible_cpu(i) {
    8158           4 :                 struct rq *rq;
    8159             : 
    8160           4 :                 rq = cpu_rq(i);
    8161           4 :                 raw_spin_lock_init(&rq->lock);
    8162           4 :                 rq->nr_running = 0;
    8163           4 :                 rq->calc_load_active = 0;
    8164           4 :                 rq->calc_load_update = jiffies + LOAD_FREQ;
    8165           4 :                 init_cfs_rq(&rq->cfs);
    8166           4 :                 init_rt_rq(&rq->rt);
    8167           4 :                 init_dl_rq(&rq->dl);
    8168             : #ifdef CONFIG_FAIR_GROUP_SCHED
    8169             :                 INIT_LIST_HEAD(&rq->leaf_cfs_rq_list);
    8170             :                 rq->tmp_alone_branch = &rq->leaf_cfs_rq_list;
    8171             :                 /*
    8172             :                  * How much CPU bandwidth does root_task_group get?
    8173             :                  *
    8174             :                  * In case of task-groups formed thr' the cgroup filesystem, it
    8175             :                  * gets 100% of the CPU resources in the system. This overall
    8176             :                  * system CPU resource is divided among the tasks of
    8177             :                  * root_task_group and its child task-groups in a fair manner,
    8178             :                  * based on each entity's (task or task-group's) weight
    8179             :                  * (se->load.weight).
    8180             :                  *
    8181             :                  * In other words, if root_task_group has 10 tasks of weight
    8182             :                  * 1024) and two child groups A0 and A1 (of weight 1024 each),
    8183             :                  * then A0's share of the CPU resource is:
    8184             :                  *
    8185             :                  *      A0's bandwidth = 1024 / (10*1024 + 1024 + 1024) = 8.33%
    8186             :                  *
    8187             :                  * We achieve this by letting root_task_group's tasks sit
    8188             :                  * directly in rq->cfs (i.e root_task_group->se[] = NULL).
    8189             :                  */
    8190             :                 init_tg_cfs_entry(&root_task_group, &rq->cfs, NULL, i, NULL);
    8191             : #endif /* CONFIG_FAIR_GROUP_SCHED */
    8192             : 
    8193           4 :                 rq->rt.rt_runtime = def_rt_bandwidth.rt_runtime;
    8194             : #ifdef CONFIG_RT_GROUP_SCHED
    8195             :                 init_tg_rt_entry(&root_task_group, &rq->rt, NULL, i, NULL);
    8196             : #endif
    8197             : #ifdef CONFIG_SMP
    8198           4 :                 rq->sd = NULL;
    8199           4 :                 rq->rd = NULL;
    8200           4 :                 rq->cpu_capacity = rq->cpu_capacity_orig = SCHED_CAPACITY_SCALE;
    8201           4 :                 rq->balance_callback = NULL;
    8202           4 :                 rq->active_balance = 0;
    8203           4 :                 rq->next_balance = jiffies;
    8204           4 :                 rq->push_cpu = 0;
    8205           4 :                 rq->cpu = i;
    8206           4 :                 rq->online = 0;
    8207           4 :                 rq->idle_stamp = 0;
    8208           4 :                 rq->avg_idle = 2*sysctl_sched_migration_cost;
    8209           4 :                 rq->max_idle_balance_cost = sysctl_sched_migration_cost;
    8210             : 
    8211           4 :                 INIT_LIST_HEAD(&rq->cfs_tasks);
    8212             : 
    8213           4 :                 rq_attach_root(rq, &def_root_domain);
    8214             : #ifdef CONFIG_NO_HZ_COMMON
    8215           4 :                 rq->last_blocked_load_update_tick = jiffies;
    8216           4 :                 atomic_set(&rq->nohz_flags, 0);
    8217             : 
    8218           4 :                 INIT_CSD(&rq->nohz_csd, nohz_csd_func, rq);
    8219             : #endif
    8220             : #ifdef CONFIG_HOTPLUG_CPU
    8221           4 :                 rcuwait_init(&rq->hotplug_wait);
    8222             : #endif
    8223             : #endif /* CONFIG_SMP */
    8224           4 :                 hrtick_rq_init(rq);
    8225           9 :                 atomic_set(&rq->nr_iowait, 0);
    8226             :         }
    8227             : 
    8228           1 :         set_load_weight(&init_task, false);
    8229             : 
    8230             :         /*
    8231             :          * The boot idle thread does lazy MMU switching as well:
    8232             :          */
    8233           1 :         mmgrab(&init_mm);
    8234           1 :         enter_lazy_tlb(&init_mm, current);
    8235             : 
    8236             :         /*
    8237             :          * Make us the idle thread. Technically, schedule() should not be
    8238             :          * called from this thread, however somewhere below it might be,
    8239             :          * but because we are the idle thread, we just pick up running again
    8240             :          * when this runqueue becomes "idle".
    8241             :          */
    8242           1 :         init_idle(current, smp_processor_id());
    8243             : 
    8244           1 :         calc_load_update = jiffies + LOAD_FREQ;
    8245             : 
    8246             : #ifdef CONFIG_SMP
    8247           1 :         idle_thread_set_boot_cpu();
    8248             : #endif
    8249           1 :         init_sched_fair_class();
    8250             : 
    8251           1 :         init_schedstats();
    8252             : 
    8253           1 :         psi_init();
    8254             : 
    8255           1 :         init_uclamp();
    8256             : 
    8257           1 :         scheduler_running = 1;
    8258           1 : }
    8259             : 
    8260             : #ifdef CONFIG_DEBUG_ATOMIC_SLEEP
    8261     3128469 : static inline int preempt_count_equals(int preempt_offset)
    8262             : {
    8263     3128469 :         int nested = preempt_count() + rcu_preempt_depth();
    8264             : 
    8265     3128469 :         return (nested == preempt_offset);
    8266             : }
    8267             : 
    8268     2639150 : void __might_sleep(const char *file, int line, int preempt_offset)
    8269             : {
    8270             :         /*
    8271             :          * Blocking primitives will set (and therefore destroy) current->state,
    8272             :          * since we will exit with TASK_RUNNING make sure we enter with it,
    8273             :          * otherwise we will destroy state.
    8274             :          */
    8275     2639644 :         WARN_ONCE(current->state != TASK_RUNNING && current->task_state_change,
    8276             :                         "do not call blocking ops when !TASK_RUNNING; "
    8277             :                         "state=%lx set at [<%p>] %pS\n",
    8278             :                         current->state,
    8279             :                         (void *)current->task_state_change,
    8280             :                         (void *)current->task_state_change);
    8281             : 
    8282     2639150 :         ___might_sleep(file, line, preempt_offset);
    8283     2641758 : }
    8284             : EXPORT_SYMBOL(__might_sleep);
    8285             : 
    8286     3125595 : void ___might_sleep(const char *file, int line, int preempt_offset)
    8287             : {
    8288             :         /* Ratelimiting timestamp: */
    8289     3125595 :         static unsigned long prev_jiffy;
    8290             : 
    8291     3125595 :         unsigned long preempt_disable_ip;
    8292             : 
    8293             :         /* WARN_ON_ONCE() by default, no rate limit required: */
    8294     9379512 :         rcu_sleep_check();
    8295             : 
    8296     3128469 :         if ((preempt_count_equals(preempt_offset) && !irqs_disabled() &&
    8297     3126608 :              !is_idle_task(current) && !current->non_block_count) ||
    8298        1763 :             system_state == SYSTEM_BOOTING || system_state > SYSTEM_RUNNING ||
    8299             :             oops_in_progress)
    8300     3128938 :                 return;
    8301             : 
    8302           0 :         if (time_before(jiffies, prev_jiffy + HZ) && prev_jiffy)
    8303             :                 return;
    8304           0 :         prev_jiffy = jiffies;
    8305             : 
    8306             :         /* Save this before calling printk(), since that will clobber it: */
    8307           0 :         preempt_disable_ip = get_preempt_disable_ip(current);
    8308             : 
    8309           0 :         printk(KERN_ERR
    8310             :                 "BUG: sleeping function called from invalid context at %s:%d\n",
    8311             :                         file, line);
    8312           0 :         printk(KERN_ERR
    8313             :                 "in_atomic(): %d, irqs_disabled(): %d, non_block: %d, pid: %d, name: %s\n",
    8314           0 :                         in_atomic(), irqs_disabled(), current->non_block_count,
    8315           0 :                         current->pid, current->comm);
    8316             : 
    8317           0 :         if (task_stack_end_corrupted(current))
    8318           0 :                 printk(KERN_EMERG "Thread overran stack, or stack corrupted\n");
    8319             : 
    8320           0 :         debug_show_held_locks(current);
    8321           0 :         if (irqs_disabled())
    8322           0 :                 print_irqtrace_events(current);
    8323           0 :         if (IS_ENABLED(CONFIG_DEBUG_PREEMPT)
    8324             :             && !preempt_count_equals(preempt_offset)) {
    8325             :                 pr_err("Preemption disabled at:");
    8326             :                 print_ip_sym(KERN_ERR, preempt_disable_ip);
    8327             :         }
    8328           0 :         dump_stack();
    8329           0 :         add_taint(TAINT_WARN, LOCKDEP_STILL_OK);
    8330             : }
    8331             : EXPORT_SYMBOL(___might_sleep);
    8332             : 
    8333           0 : void __cant_sleep(const char *file, int line, int preempt_offset)
    8334             : {
    8335           0 :         static unsigned long prev_jiffy;
    8336             : 
    8337           0 :         if (irqs_disabled())
    8338             :                 return;
    8339             : 
    8340           0 :         if (!IS_ENABLED(CONFIG_PREEMPT_COUNT))
    8341             :                 return;
    8342             : 
    8343           0 :         if (preempt_count() > preempt_offset)
    8344             :                 return;
    8345             : 
    8346           0 :         if (time_before(jiffies, prev_jiffy + HZ) && prev_jiffy)
    8347             :                 return;
    8348           0 :         prev_jiffy = jiffies;
    8349             : 
    8350           0 :         printk(KERN_ERR "BUG: assuming atomic context at %s:%d\n", file, line);
    8351           0 :         printk(KERN_ERR "in_atomic(): %d, irqs_disabled(): %d, pid: %d, name: %s\n",
    8352           0 :                         in_atomic(), irqs_disabled(),
    8353           0 :                         current->pid, current->comm);
    8354             : 
    8355           0 :         debug_show_held_locks(current);
    8356           0 :         dump_stack();
    8357           0 :         add_taint(TAINT_WARN, LOCKDEP_STILL_OK);
    8358             : }
    8359             : EXPORT_SYMBOL_GPL(__cant_sleep);
    8360             : 
    8361             : #ifdef CONFIG_SMP
    8362        1068 : void __cant_migrate(const char *file, int line)
    8363             : {
    8364        1068 :         static unsigned long prev_jiffy;
    8365             : 
    8366        1068 :         if (irqs_disabled())
    8367             :                 return;
    8368             : 
    8369        1068 :         if (is_migration_disabled(current))
    8370             :                 return;
    8371             : 
    8372           0 :         if (!IS_ENABLED(CONFIG_PREEMPT_COUNT))
    8373             :                 return;
    8374             : 
    8375           0 :         if (preempt_count() > 0)
    8376             :                 return;
    8377             : 
    8378           0 :         if (time_before(jiffies, prev_jiffy + HZ) && prev_jiffy)
    8379             :                 return;
    8380           0 :         prev_jiffy = jiffies;
    8381             : 
    8382           0 :         pr_err("BUG: assuming non migratable context at %s:%d\n", file, line);
    8383           0 :         pr_err("in_atomic(): %d, irqs_disabled(): %d, migration_disabled() %u pid: %d, name: %s\n",
    8384             :                in_atomic(), irqs_disabled(), is_migration_disabled(current),
    8385             :                current->pid, current->comm);
    8386             : 
    8387           0 :         debug_show_held_locks(current);
    8388           0 :         dump_stack();
    8389           0 :         add_taint(TAINT_WARN, LOCKDEP_STILL_OK);
    8390             : }
    8391             : EXPORT_SYMBOL_GPL(__cant_migrate);
    8392             : #endif
    8393             : #endif
    8394             : 
    8395             : #ifdef CONFIG_MAGIC_SYSRQ
    8396           0 : void normalize_rt_tasks(void)
    8397             : {
    8398           0 :         struct task_struct *g, *p;
    8399           0 :         struct sched_attr attr = {
    8400             :                 .sched_policy = SCHED_NORMAL,
    8401             :         };
    8402             : 
    8403           0 :         read_lock(&tasklist_lock);
    8404           0 :         for_each_process_thread(g, p) {
    8405             :                 /*
    8406             :                  * Only normalize user tasks:
    8407             :                  */
    8408           0 :                 if (p->flags & PF_KTHREAD)
    8409           0 :                         continue;
    8410             : 
    8411           0 :                 p->se.exec_start = 0;
    8412           0 :                 schedstat_set(p->se.statistics.wait_start,  0);
    8413           0 :                 schedstat_set(p->se.statistics.sleep_start, 0);
    8414           0 :                 schedstat_set(p->se.statistics.block_start, 0);
    8415             : 
    8416           0 :                 if (!dl_task(p) && !rt_task(p)) {
    8417             :                         /*
    8418             :                          * Renice negative nice level userspace
    8419             :                          * tasks back to 0:
    8420             :                          */
    8421           0 :                         if (task_nice(p) < 0)
    8422           0 :                                 set_user_nice(p, 0);
    8423           0 :                         continue;
    8424             :                 }
    8425             : 
    8426           0 :                 __sched_setscheduler(p, &attr, false, false);
    8427             :         }
    8428           0 :         read_unlock(&tasklist_lock);
    8429           0 : }
    8430             : 
    8431             : #endif /* CONFIG_MAGIC_SYSRQ */
    8432             : 
    8433             : #if defined(CONFIG_IA64) || defined(CONFIG_KGDB_KDB)
    8434             : /*
    8435             :  * These functions are only useful for the IA64 MCA handling, or kdb.
    8436             :  *
    8437             :  * They can only be called when the whole system has been
    8438             :  * stopped - every CPU needs to be quiescent, and no scheduling
    8439             :  * activity can take place. Using them for anything else would
    8440             :  * be a serious bug, and as a result, they aren't even visible
    8441             :  * under any other configuration.
    8442             :  */
    8443             : 
    8444             : /**
    8445             :  * curr_task - return the current task for a given CPU.
    8446             :  * @cpu: the processor in question.
    8447             :  *
    8448             :  * ONLY VALID WHEN THE WHOLE SYSTEM IS STOPPED!
    8449             :  *
    8450             :  * Return: The current task for @cpu.
    8451             :  */
    8452             : struct task_struct *curr_task(int cpu)
    8453             : {
    8454             :         return cpu_curr(cpu);
    8455             : }
    8456             : 
    8457             : #endif /* defined(CONFIG_IA64) || defined(CONFIG_KGDB_KDB) */
    8458             : 
    8459             : #ifdef CONFIG_IA64
    8460             : /**
    8461             :  * ia64_set_curr_task - set the current task for a given CPU.
    8462             :  * @cpu: the processor in question.
    8463             :  * @p: the task pointer to set.
    8464             :  *
    8465             :  * Description: This function must only be used when non-maskable interrupts
    8466             :  * are serviced on a separate stack. It allows the architecture to switch the
    8467             :  * notion of the current task on a CPU in a non-blocking manner. This function
    8468             :  * must be called with all CPU's synchronized, and interrupts disabled, the
    8469             :  * and caller must save the original value of the current task (see
    8470             :  * curr_task() above) and restore that value before reenabling interrupts and
    8471             :  * re-starting the system.
    8472             :  *
    8473             :  * ONLY VALID WHEN THE WHOLE SYSTEM IS STOPPED!
    8474             :  */
    8475             : void ia64_set_curr_task(int cpu, struct task_struct *p)
    8476             : {
    8477             :         cpu_curr(cpu) = p;
    8478             : }
    8479             : 
    8480             : #endif
    8481             : 
    8482             : #ifdef CONFIG_CGROUP_SCHED
    8483             : /* task_group_lock serializes the addition/removal of task groups */
    8484             : static DEFINE_SPINLOCK(task_group_lock);
    8485             : 
    8486             : static inline void alloc_uclamp_sched_group(struct task_group *tg,
    8487             :                                             struct task_group *parent)
    8488             : {
    8489             : #ifdef CONFIG_UCLAMP_TASK_GROUP
    8490             :         enum uclamp_id clamp_id;
    8491             : 
    8492             :         for_each_clamp_id(clamp_id) {
    8493             :                 uclamp_se_set(&tg->uclamp_req[clamp_id],
    8494             :                               uclamp_none(clamp_id), false);
    8495             :                 tg->uclamp[clamp_id] = parent->uclamp[clamp_id];
    8496             :         }
    8497             : #endif
    8498             : }
    8499             : 
    8500             : static void sched_free_group(struct task_group *tg)
    8501             : {
    8502             :         free_fair_sched_group(tg);
    8503             :         free_rt_sched_group(tg);
    8504             :         autogroup_free(tg);
    8505             :         kmem_cache_free(task_group_cache, tg);
    8506             : }
    8507             : 
    8508             : /* allocate runqueue etc for a new task group */
    8509             : struct task_group *sched_create_group(struct task_group *parent)
    8510             : {
    8511             :         struct task_group *tg;
    8512             : 
    8513             :         tg = kmem_cache_alloc(task_group_cache, GFP_KERNEL | __GFP_ZERO);
    8514             :         if (!tg)
    8515             :                 return ERR_PTR(-ENOMEM);
    8516             : 
    8517             :         if (!alloc_fair_sched_group(tg, parent))
    8518             :                 goto err;
    8519             : 
    8520             :         if (!alloc_rt_sched_group(tg, parent))
    8521             :                 goto err;
    8522             : 
    8523             :         alloc_uclamp_sched_group(tg, parent);
    8524             : 
    8525             :         return tg;
    8526             : 
    8527             : err:
    8528             :         sched_free_group(tg);
    8529             :         return ERR_PTR(-ENOMEM);
    8530             : }
    8531             : 
    8532             : void sched_online_group(struct task_group *tg, struct task_group *parent)
    8533             : {
    8534             :         unsigned long flags;
    8535             : 
    8536             :         spin_lock_irqsave(&task_group_lock, flags);
    8537             :         list_add_rcu(&tg->list, &task_groups);
    8538             : 
    8539             :         /* Root should already exist: */
    8540             :         WARN_ON(!parent);
    8541             : 
    8542             :         tg->parent = parent;
    8543             :         INIT_LIST_HEAD(&tg->children);
    8544             :         list_add_rcu(&tg->siblings, &parent->children);
    8545             :         spin_unlock_irqrestore(&task_group_lock, flags);
    8546             : 
    8547             :         online_fair_sched_group(tg);
    8548             : }
    8549             : 
    8550             : /* rcu callback to free various structures associated with a task group */
    8551             : static void sched_free_group_rcu(struct rcu_head *rhp)
    8552             : {
    8553             :         /* Now it should be safe to free those cfs_rqs: */
    8554             :         sched_free_group(container_of(rhp, struct task_group, rcu));
    8555             : }
    8556             : 
    8557             : void sched_destroy_group(struct task_group *tg)
    8558             : {
    8559             :         /* Wait for possible concurrent references to cfs_rqs complete: */
    8560             :         call_rcu(&tg->rcu, sched_free_group_rcu);
    8561             : }
    8562             : 
    8563             : void sched_offline_group(struct task_group *tg)
    8564             : {
    8565             :         unsigned long flags;
    8566             : 
    8567             :         /* End participation in shares distribution: */
    8568             :         unregister_fair_sched_group(tg);
    8569             : 
    8570             :         spin_lock_irqsave(&task_group_lock, flags);
    8571             :         list_del_rcu(&tg->list);
    8572             :         list_del_rcu(&tg->siblings);
    8573             :         spin_unlock_irqrestore(&task_group_lock, flags);
    8574             : }
    8575             : 
    8576             : static void sched_change_group(struct task_struct *tsk, int type)
    8577             : {
    8578             :         struct task_group *tg;
    8579             : 
    8580             :         /*
    8581             :          * All callers are synchronized by task_rq_lock(); we do not use RCU
    8582             :          * which is pointless here. Thus, we pass "true" to task_css_check()
    8583             :          * to prevent lockdep warnings.
    8584             :          */
    8585             :         tg = container_of(task_css_check(tsk, cpu_cgrp_id, true),
    8586             :                           struct task_group, css);
    8587             :         tg = autogroup_task_group(tsk, tg);
    8588             :         tsk->sched_task_group = tg;
    8589             : 
    8590             : #ifdef CONFIG_FAIR_GROUP_SCHED
    8591             :         if (tsk->sched_class->task_change_group)
    8592             :                 tsk->sched_class->task_change_group(tsk, type);
    8593             :         else
    8594             : #endif
    8595             :                 set_task_rq(tsk, task_cpu(tsk));
    8596             : }
    8597             : 
    8598             : /*
    8599             :  * Change task's runqueue when it moves between groups.
    8600             :  *
    8601             :  * The caller of this function should have put the task in its new group by
    8602             :  * now. This function just updates tsk->se.cfs_rq and tsk->se.parent to reflect
    8603             :  * its new group.
    8604             :  */
    8605             : void sched_move_task(struct task_struct *tsk)
    8606             : {
    8607             :         int queued, running, queue_flags =
    8608             :                 DEQUEUE_SAVE | DEQUEUE_MOVE | DEQUEUE_NOCLOCK;
    8609             :         struct rq_flags rf;
    8610             :         struct rq *rq;
    8611             : 
    8612             :         rq = task_rq_lock(tsk, &rf);
    8613             :         update_rq_clock(rq);
    8614             : 
    8615             :         running = task_current(rq, tsk);
    8616             :         queued = task_on_rq_queued(tsk);
    8617             : 
    8618             :         if (queued)
    8619             :                 dequeue_task(rq, tsk, queue_flags);
    8620             :         if (running)
    8621             :                 put_prev_task(rq, tsk);
    8622             : 
    8623             :         sched_change_group(tsk, TASK_MOVE_GROUP);
    8624             : 
    8625             :         if (queued)
    8626             :                 enqueue_task(rq, tsk, queue_flags);
    8627             :         if (running) {
    8628             :                 set_next_task(rq, tsk);
    8629             :                 /*
    8630             :                  * After changing group, the running task may have joined a
    8631             :                  * throttled one but it's still the running task. Trigger a
    8632             :                  * resched to make sure that task can still run.
    8633             :                  */
    8634             :                 resched_curr(rq);
    8635             :         }
    8636             : 
    8637             :         task_rq_unlock(rq, tsk, &rf);
    8638             : }
    8639             : 
    8640             : static inline struct task_group *css_tg(struct cgroup_subsys_state *css)
    8641             : {
    8642             :         return css ? container_of(css, struct task_group, css) : NULL;
    8643             : }
    8644             : 
    8645             : static struct cgroup_subsys_state *
    8646             : cpu_cgroup_css_alloc(struct cgroup_subsys_state *parent_css)
    8647             : {
    8648             :         struct task_group *parent = css_tg(parent_css);
    8649             :         struct task_group *tg;
    8650             : 
    8651             :         if (!parent) {
    8652             :                 /* This is early initialization for the top cgroup */
    8653             :                 return &root_task_group.css;
    8654             :         }
    8655             : 
    8656             :         tg = sched_create_group(parent);
    8657             :         if (IS_ERR(tg))
    8658             :                 return ERR_PTR(-ENOMEM);
    8659             : 
    8660             :         return &tg->css;
    8661             : }
    8662             : 
    8663             : /* Expose task group only after completing cgroup initialization */
    8664             : static int cpu_cgroup_css_online(struct cgroup_subsys_state *css)
    8665             : {
    8666             :         struct task_group *tg = css_tg(css);
    8667             :         struct task_group *parent = css_tg(css->parent);
    8668             : 
    8669             :         if (parent)
    8670             :                 sched_online_group(tg, parent);
    8671             : 
    8672             : #ifdef CONFIG_UCLAMP_TASK_GROUP
    8673             :         /* Propagate the effective uclamp value for the new group */
    8674             :         cpu_util_update_eff(css);
    8675             : #endif
    8676             : 
    8677             :         return 0;
    8678             : }
    8679             : 
    8680             : static void cpu_cgroup_css_released(struct cgroup_subsys_state *css)
    8681             : {
    8682             :         struct task_group *tg = css_tg(css);
    8683             : 
    8684             :         sched_offline_group(tg);
    8685             : }
    8686             : 
    8687             : static void cpu_cgroup_css_free(struct cgroup_subsys_state *css)
    8688             : {
    8689             :         struct task_group *tg = css_tg(css);
    8690             : 
    8691             :         /*
    8692             :          * Relies on the RCU grace period between css_released() and this.
    8693             :          */
    8694             :         sched_free_group(tg);
    8695             : }
    8696             : 
    8697             : /*
    8698             :  * This is called before wake_up_new_task(), therefore we really only
    8699             :  * have to set its group bits, all the other stuff does not apply.
    8700             :  */
    8701             : static void cpu_cgroup_fork(struct task_struct *task)
    8702             : {
    8703             :         struct rq_flags rf;
    8704             :         struct rq *rq;
    8705             : 
    8706             :         rq = task_rq_lock(task, &rf);
    8707             : 
    8708             :         update_rq_clock(rq);
    8709             :         sched_change_group(task, TASK_SET_GROUP);
    8710             : 
    8711             :         task_rq_unlock(rq, task, &rf);
    8712             : }
    8713             : 
    8714             : static int cpu_cgroup_can_attach(struct cgroup_taskset *tset)
    8715             : {
    8716             :         struct task_struct *task;
    8717             :         struct cgroup_subsys_state *css;
    8718             :         int ret = 0;
    8719             : 
    8720             :         cgroup_taskset_for_each(task, css, tset) {
    8721             : #ifdef CONFIG_RT_GROUP_SCHED
    8722             :                 if (!sched_rt_can_attach(css_tg(css), task))
    8723             :                         return -EINVAL;
    8724             : #endif
    8725             :                 /*
    8726             :                  * Serialize against wake_up_new_task() such that if it's
    8727             :                  * running, we're sure to observe its full state.
    8728             :                  */
    8729             :                 raw_spin_lock_irq(&task->pi_lock);
    8730             :                 /*
    8731             :                  * Avoid calling sched_move_task() before wake_up_new_task()
    8732             :                  * has happened. This would lead to problems with PELT, due to
    8733             :                  * move wanting to detach+attach while we're not attached yet.
    8734             :                  */
    8735             :                 if (task->state == TASK_NEW)
    8736             :                         ret = -EINVAL;
    8737             :                 raw_spin_unlock_irq(&task->pi_lock);
    8738             : 
    8739             :                 if (ret)
    8740             :                         break;
    8741             :         }
    8742             :         return ret;
    8743             : }
    8744             : 
    8745             : static void cpu_cgroup_attach(struct cgroup_taskset *tset)
    8746             : {
    8747             :         struct task_struct *task;
    8748             :         struct cgroup_subsys_state *css;
    8749             : 
    8750             :         cgroup_taskset_for_each(task, css, tset)
    8751             :                 sched_move_task(task);
    8752             : }
    8753             : 
    8754             : #ifdef CONFIG_UCLAMP_TASK_GROUP
    8755             : static void cpu_util_update_eff(struct cgroup_subsys_state *css)
    8756             : {
    8757             :         struct cgroup_subsys_state *top_css = css;
    8758             :         struct uclamp_se *uc_parent = NULL;
    8759             :         struct uclamp_se *uc_se = NULL;
    8760             :         unsigned int eff[UCLAMP_CNT];
    8761             :         enum uclamp_id clamp_id;
    8762             :         unsigned int clamps;
    8763             : 
    8764             :         css_for_each_descendant_pre(css, top_css) {
    8765             :                 uc_parent = css_tg(css)->parent
    8766             :                         ? css_tg(css)->parent->uclamp : NULL;
    8767             : 
    8768             :                 for_each_clamp_id(clamp_id) {
    8769             :                         /* Assume effective clamps matches requested clamps */
    8770             :                         eff[clamp_id] = css_tg(css)->uclamp_req[clamp_id].value;
    8771             :                         /* Cap effective clamps with parent's effective clamps */
    8772             :                         if (uc_parent &&
    8773             :                             eff[clamp_id] > uc_parent[clamp_id].value) {
    8774             :                                 eff[clamp_id] = uc_parent[clamp_id].value;
    8775             :                         }
    8776             :                 }
    8777             :                 /* Ensure protection is always capped by limit */
    8778             :                 eff[UCLAMP_MIN] = min(eff[UCLAMP_MIN], eff[UCLAMP_MAX]);
    8779             : 
    8780             :                 /* Propagate most restrictive effective clamps */
    8781             :                 clamps = 0x0;
    8782             :                 uc_se = css_tg(css)->uclamp;
    8783             :                 for_each_clamp_id(clamp_id) {
    8784             :                         if (eff[clamp_id] == uc_se[clamp_id].value)
    8785             :                                 continue;
    8786             :                         uc_se[clamp_id].value = eff[clamp_id];
    8787             :                         uc_se[clamp_id].bucket_id = uclamp_bucket_id(eff[clamp_id]);
    8788             :                         clamps |= (0x1 << clamp_id);
    8789             :                 }
    8790             :                 if (!clamps) {
    8791             :                         css = css_rightmost_descendant(css);
    8792             :                         continue;
    8793             :                 }
    8794             : 
    8795             :                 /* Immediately update descendants RUNNABLE tasks */
    8796             :                 uclamp_update_active_tasks(css, clamps);
    8797             :         }
    8798             : }
    8799             : 
    8800             : /*
    8801             :  * Integer 10^N with a given N exponent by casting to integer the literal "1eN"
    8802             :  * C expression. Since there is no way to convert a macro argument (N) into a
    8803             :  * character constant, use two levels of macros.
    8804             :  */
    8805             : #define _POW10(exp) ((unsigned int)1e##exp)
    8806             : #define POW10(exp) _POW10(exp)
    8807             : 
    8808             : struct uclamp_request {
    8809             : #define UCLAMP_PERCENT_SHIFT    2
    8810             : #define UCLAMP_PERCENT_SCALE    (100 * POW10(UCLAMP_PERCENT_SHIFT))
    8811             :         s64 percent;
    8812             :         u64 util;
    8813             :         int ret;
    8814             : };
    8815             : 
    8816             : static inline struct uclamp_request
    8817             : capacity_from_percent(char *buf)
    8818             : {
    8819             :         struct uclamp_request req = {
    8820             :                 .percent = UCLAMP_PERCENT_SCALE,
    8821             :                 .util = SCHED_CAPACITY_SCALE,
    8822             :                 .ret = 0,
    8823             :         };
    8824             : 
    8825             :         buf = strim(buf);
    8826             :         if (strcmp(buf, "max")) {
    8827             :                 req.ret = cgroup_parse_float(buf, UCLAMP_PERCENT_SHIFT,
    8828             :                                              &req.percent);
    8829             :                 if (req.ret)
    8830             :                         return req;
    8831             :                 if ((u64)req.percent > UCLAMP_PERCENT_SCALE) {
    8832             :                         req.ret = -ERANGE;
    8833             :                         return req;
    8834             :                 }
    8835             : 
    8836             :                 req.util = req.percent << SCHED_CAPACITY_SHIFT;
    8837             :                 req.util = DIV_ROUND_CLOSEST_ULL(req.util, UCLAMP_PERCENT_SCALE);
    8838             :         }
    8839             : 
    8840             :         return req;
    8841             : }
    8842             : 
    8843             : static ssize_t cpu_uclamp_write(struct kernfs_open_file *of, char *buf,
    8844             :                                 size_t nbytes, loff_t off,
    8845             :                                 enum uclamp_id clamp_id)
    8846             : {
    8847             :         struct uclamp_request req;
    8848             :         struct task_group *tg;
    8849             : 
    8850             :         req = capacity_from_percent(buf);
    8851             :         if (req.ret)
    8852             :                 return req.ret;
    8853             : 
    8854             :         static_branch_enable(&sched_uclamp_used);
    8855             : 
    8856             :         mutex_lock(&uclamp_mutex);
    8857             :         rcu_read_lock();
    8858             : 
    8859             :         tg = css_tg(of_css(of));
    8860             :         if (tg->uclamp_req[clamp_id].value != req.util)
    8861             :                 uclamp_se_set(&tg->uclamp_req[clamp_id], req.util, false);
    8862             : 
    8863             :         /*
    8864             :          * Because of not recoverable conversion rounding we keep track of the
    8865             :          * exact requested value
    8866             :          */
    8867             :         tg->uclamp_pct[clamp_id] = req.percent;
    8868             : 
    8869             :         /* Update effective clamps to track the most restrictive value */
    8870             :         cpu_util_update_eff(of_css(of));
    8871             : 
    8872             :         rcu_read_unlock();
    8873             :         mutex_unlock(&uclamp_mutex);
    8874             : 
    8875             :         return nbytes;
    8876             : }
    8877             : 
    8878             : static ssize_t cpu_uclamp_min_write(struct kernfs_open_file *of,
    8879             :                                     char *buf, size_t nbytes,
    8880             :                                     loff_t off)
    8881             : {
    8882             :         return cpu_uclamp_write(of, buf, nbytes, off, UCLAMP_MIN);
    8883             : }
    8884             : 
    8885             : static ssize_t cpu_uclamp_max_write(struct kernfs_open_file *of,
    8886             :                                     char *buf, size_t nbytes,
    8887             :                                     loff_t off)
    8888             : {
    8889             :         return cpu_uclamp_write(of, buf, nbytes, off, UCLAMP_MAX);
    8890             : }
    8891             : 
    8892             : static inline void cpu_uclamp_print(struct seq_file *sf,
    8893             :                                     enum uclamp_id clamp_id)
    8894             : {
    8895             :         struct task_group *tg;
    8896             :         u64 util_clamp;
    8897             :         u64 percent;
    8898             :         u32 rem;
    8899             : 
    8900             :         rcu_read_lock();
    8901             :         tg = css_tg(seq_css(sf));
    8902             :         util_clamp = tg->uclamp_req[clamp_id].value;
    8903             :         rcu_read_unlock();
    8904             : 
    8905             :         if (util_clamp == SCHED_CAPACITY_SCALE) {
    8906             :                 seq_puts(sf, "max\n");
    8907             :                 return;
    8908             :         }
    8909             : 
    8910             :         percent = tg->uclamp_pct[clamp_id];
    8911             :         percent = div_u64_rem(percent, POW10(UCLAMP_PERCENT_SHIFT), &rem);
    8912             :         seq_printf(sf, "%llu.%0*u\n", percent, UCLAMP_PERCENT_SHIFT, rem);
    8913             : }
    8914             : 
    8915             : static int cpu_uclamp_min_show(struct seq_file *sf, void *v)
    8916             : {
    8917             :         cpu_uclamp_print(sf, UCLAMP_MIN);
    8918             :         return 0;
    8919             : }
    8920             : 
    8921             : static int cpu_uclamp_max_show(struct seq_file *sf, void *v)
    8922             : {
    8923             :         cpu_uclamp_print(sf, UCLAMP_MAX);
    8924             :         return 0;
    8925             : }
    8926             : #endif /* CONFIG_UCLAMP_TASK_GROUP */
    8927             : 
    8928             : #ifdef CONFIG_FAIR_GROUP_SCHED
    8929             : static int cpu_shares_write_u64(struct cgroup_subsys_state *css,
    8930             :                                 struct cftype *cftype, u64 shareval)
    8931             : {
    8932             :         if (shareval > scale_load_down(ULONG_MAX))
    8933             :                 shareval = MAX_SHARES;
    8934             :         return sched_group_set_shares(css_tg(css), scale_load(shareval));
    8935             : }
    8936             : 
    8937             : static u64 cpu_shares_read_u64(struct cgroup_subsys_state *css,
    8938             :                                struct cftype *cft)
    8939             : {
    8940             :         struct task_group *tg = css_tg(css);
    8941             : 
    8942             :         return (u64) scale_load_down(tg->shares);
    8943             : }
    8944             : 
    8945             : #ifdef CONFIG_CFS_BANDWIDTH
    8946             : static DEFINE_MUTEX(cfs_constraints_mutex);
    8947             : 
    8948             : const u64 max_cfs_quota_period = 1 * NSEC_PER_SEC; /* 1s */
    8949             : static const u64 min_cfs_quota_period = 1 * NSEC_PER_MSEC; /* 1ms */
    8950             : /* More than 203 days if BW_SHIFT equals 20. */
    8951             : static const u64 max_cfs_runtime = MAX_BW * NSEC_PER_USEC;
    8952             : 
    8953             : static int __cfs_schedulable(struct task_group *tg, u64 period, u64 runtime);
    8954             : 
    8955             : static int tg_set_cfs_bandwidth(struct task_group *tg, u64 period, u64 quota)
    8956             : {
    8957             :         int i, ret = 0, runtime_enabled, runtime_was_enabled;
    8958             :         struct cfs_bandwidth *cfs_b = &tg->cfs_bandwidth;
    8959             : 
    8960             :         if (tg == &root_task_group)
    8961             :                 return -EINVAL;
    8962             : 
    8963             :         /*
    8964             :          * Ensure we have at some amount of bandwidth every period.  This is
    8965             :          * to prevent reaching a state of large arrears when throttled via
    8966             :          * entity_tick() resulting in prolonged exit starvation.
    8967             :          */
    8968             :         if (quota < min_cfs_quota_period || period < min_cfs_quota_period)
    8969             :                 return -EINVAL;
    8970             : 
    8971             :         /*
    8972             :          * Likewise, bound things on the otherside by preventing insane quota
    8973             :          * periods.  This also allows us to normalize in computing quota
    8974             :          * feasibility.
    8975             :          */
    8976             :         if (period > max_cfs_quota_period)
    8977             :                 return -EINVAL;
    8978             : 
    8979             :         /*
    8980             :          * Bound quota to defend quota against overflow during bandwidth shift.
    8981             :          */
    8982             :         if (quota != RUNTIME_INF && quota > max_cfs_runtime)
    8983             :                 return -EINVAL;
    8984             : 
    8985             :         /*
    8986             :          * Prevent race between setting of cfs_rq->runtime_enabled and
    8987             :          * unthrottle_offline_cfs_rqs().
    8988             :          */
    8989             :         get_online_cpus();
    8990             :         mutex_lock(&cfs_constraints_mutex);
    8991             :         ret = __cfs_schedulable(tg, period, quota);
    8992             :         if (ret)
    8993             :                 goto out_unlock;
    8994             : 
    8995             :         runtime_enabled = quota != RUNTIME_INF;
    8996             :         runtime_was_enabled = cfs_b->quota != RUNTIME_INF;
    8997             :         /*
    8998             :          * If we need to toggle cfs_bandwidth_used, off->on must occur
    8999             :          * before making related changes, and on->off must occur afterwards
    9000             :          */
    9001             :         if (runtime_enabled && !runtime_was_enabled)
    9002             :                 cfs_bandwidth_usage_inc();
    9003             :         raw_spin_lock_irq(&cfs_b->lock);
    9004             :         cfs_b->period = ns_to_ktime(period);
    9005             :         cfs_b->quota = quota;
    9006             : 
    9007             :         __refill_cfs_bandwidth_runtime(cfs_b);
    9008             : 
    9009             :         /* Restart the period timer (if active) to handle new period expiry: */
    9010             :         if (runtime_enabled)
    9011             :                 start_cfs_bandwidth(cfs_b);
    9012             : 
    9013             :         raw_spin_unlock_irq(&cfs_b->lock);
    9014             : 
    9015             :         for_each_online_cpu(i) {
    9016             :                 struct cfs_rq *cfs_rq = tg->cfs_rq[i];
    9017             :                 struct rq *rq = cfs_rq->rq;
    9018             :                 struct rq_flags rf;
    9019             : 
    9020             :                 rq_lock_irq(rq, &rf);
    9021             :                 cfs_rq->runtime_enabled = runtime_enabled;
    9022             :                 cfs_rq->runtime_remaining = 0;
    9023             : 
    9024             :                 if (cfs_rq->throttled)
    9025             :                         unthrottle_cfs_rq(cfs_rq);
    9026             :                 rq_unlock_irq(rq, &rf);
    9027             :         }
    9028             :         if (runtime_was_enabled && !runtime_enabled)
    9029             :                 cfs_bandwidth_usage_dec();
    9030             : out_unlock:
    9031             :         mutex_unlock(&cfs_constraints_mutex);
    9032             :         put_online_cpus();
    9033             : 
    9034             :         return ret;
    9035             : }
    9036             : 
    9037             : static int tg_set_cfs_quota(struct task_group *tg, long cfs_quota_us)
    9038             : {
    9039             :         u64 quota, period;
    9040             : 
    9041             :         period = ktime_to_ns(tg->cfs_bandwidth.period);
    9042             :         if (cfs_quota_us < 0)
    9043             :                 quota = RUNTIME_INF;
    9044             :         else if ((u64)cfs_quota_us <= U64_MAX / NSEC_PER_USEC)
    9045             :                 quota = (u64)cfs_quota_us * NSEC_PER_USEC;
    9046             :         else
    9047             :                 return -EINVAL;
    9048             : 
    9049             :         return tg_set_cfs_bandwidth(tg, period, quota);
    9050             : }
    9051             : 
    9052             : static long tg_get_cfs_quota(struct task_group *tg)
    9053             : {
    9054             :         u64 quota_us;
    9055             : 
    9056             :         if (tg->cfs_bandwidth.quota == RUNTIME_INF)
    9057             :                 return -1;
    9058             : 
    9059             :         quota_us = tg->cfs_bandwidth.quota;
    9060             :         do_div(quota_us, NSEC_PER_USEC);
    9061             : 
    9062             :         return quota_us;
    9063             : }
    9064             : 
    9065             : static int tg_set_cfs_period(struct task_group *tg, long cfs_period_us)
    9066             : {
    9067             :         u64 quota, period;
    9068             : 
    9069             :         if ((u64)cfs_period_us > U64_MAX / NSEC_PER_USEC)
    9070             :                 return -EINVAL;
    9071             : 
    9072             :         period = (u64)cfs_period_us * NSEC_PER_USEC;
    9073             :         quota = tg->cfs_bandwidth.quota;
    9074             : 
    9075             :         return tg_set_cfs_bandwidth(tg, period, quota);
    9076             : }
    9077             : 
    9078             : static long tg_get_cfs_period(struct task_group *tg)
    9079             : {
    9080             :         u64 cfs_period_us;
    9081             : 
    9082             :         cfs_period_us = ktime_to_ns(tg->cfs_bandwidth.period);
    9083             :         do_div(cfs_period_us, NSEC_PER_USEC);
    9084             : 
    9085             :         return cfs_period_us;
    9086             : }
    9087             : 
    9088             : static s64 cpu_cfs_quota_read_s64(struct cgroup_subsys_state *css,
    9089             :                                   struct cftype *cft)
    9090             : {
    9091             :         return tg_get_cfs_quota(css_tg(css));
    9092             : }
    9093             : 
    9094             : static int cpu_cfs_quota_write_s64(struct cgroup_subsys_state *css,
    9095             :                                    struct cftype *cftype, s64 cfs_quota_us)
    9096             : {
    9097             :         return tg_set_cfs_quota(css_tg(css), cfs_quota_us);
    9098             : }
    9099             : 
    9100             : static u64 cpu_cfs_period_read_u64(struct cgroup_subsys_state *css,
    9101             :                                    struct cftype *cft)
    9102             : {
    9103             :         return tg_get_cfs_period(css_tg(css));
    9104             : }
    9105             : 
    9106             : static int cpu_cfs_period_write_u64(struct cgroup_subsys_state *css,
    9107             :                                     struct cftype *cftype, u64 cfs_period_us)
    9108             : {
    9109             :         return tg_set_cfs_period(css_tg(css), cfs_period_us);
    9110             : }
    9111             : 
    9112             : struct cfs_schedulable_data {
    9113             :         struct task_group *tg;
    9114             :         u64 period, quota;
    9115             : };
    9116             : 
    9117             : /*
    9118             :  * normalize group quota/period to be quota/max_period
    9119             :  * note: units are usecs
    9120             :  */
    9121             : static u64 normalize_cfs_quota(struct task_group *tg,
    9122             :                                struct cfs_schedulable_data *d)
    9123             : {
    9124             :         u64 quota, period;
    9125             : 
    9126             :         if (tg == d->tg) {
    9127             :                 period = d->period;
    9128             :                 quota = d->quota;
    9129             :         } else {
    9130             :                 period = tg_get_cfs_period(tg);
    9131             :                 quota = tg_get_cfs_quota(tg);
    9132             :         }
    9133             : 
    9134             :         /* note: these should typically be equivalent */
    9135             :         if (quota == RUNTIME_INF || quota == -1)
    9136             :                 return RUNTIME_INF;
    9137             : 
    9138             :         return to_ratio(period, quota);
    9139             : }
    9140             : 
    9141             : static int tg_cfs_schedulable_down(struct task_group *tg, void *data)
    9142             : {
    9143             :         struct cfs_schedulable_data *d = data;
    9144             :         struct cfs_bandwidth *cfs_b = &tg->cfs_bandwidth;
    9145             :         s64 quota = 0, parent_quota = -1;
    9146             : 
    9147             :         if (!tg->parent) {
    9148             :                 quota = RUNTIME_INF;
    9149             :         } else {
    9150             :                 struct cfs_bandwidth *parent_b = &tg->parent->cfs_bandwidth;
    9151             : 
    9152             :                 quota = normalize_cfs_quota(tg, d);
    9153             :                 parent_quota = parent_b->hierarchical_quota;
    9154             : 
    9155             :                 /*
    9156             :                  * Ensure max(child_quota) <= parent_quota.  On cgroup2,
    9157             :                  * always take the min.  On cgroup1, only inherit when no
    9158             :                  * limit is set:
    9159             :                  */
    9160             :                 if (cgroup_subsys_on_dfl(cpu_cgrp_subsys)) {
    9161             :                         quota = min(quota, parent_quota);
    9162             :                 } else {
    9163             :                         if (quota == RUNTIME_INF)
    9164             :                                 quota = parent_quota;
    9165             :                         else if (parent_quota != RUNTIME_INF && quota > parent_quota)
    9166             :                                 return -EINVAL;
    9167             :                 }
    9168             :         }
    9169             :         cfs_b->hierarchical_quota = quota;
    9170             : 
    9171             :         return 0;
    9172             : }
    9173             : 
    9174             : static int __cfs_schedulable(struct task_group *tg, u64 period, u64 quota)
    9175             : {
    9176             :         int ret;
    9177             :         struct cfs_schedulable_data data = {
    9178             :                 .tg = tg,
    9179             :                 .period = period,
    9180             :                 .quota = quota,
    9181             :         };
    9182             : 
    9183             :         if (quota != RUNTIME_INF) {
    9184             :                 do_div(data.period, NSEC_PER_USEC);
    9185             :                 do_div(data.quota, NSEC_PER_USEC);
    9186             :         }
    9187             : 
    9188             :         rcu_read_lock();
    9189             :         ret = walk_tg_tree(tg_cfs_schedulable_down, tg_nop, &data);
    9190             :         rcu_read_unlock();
    9191             : 
    9192             :         return ret;
    9193             : }
    9194             : 
    9195             : static int cpu_cfs_stat_show(struct seq_file *sf, void *v)
    9196             : {
    9197             :         struct task_group *tg = css_tg(seq_css(sf));
    9198             :         struct cfs_bandwidth *cfs_b = &tg->cfs_bandwidth;
    9199             : 
    9200             :         seq_printf(sf, "nr_periods %d\n", cfs_b->nr_periods);
    9201             :         seq_printf(sf, "nr_throttled %d\n", cfs_b->nr_throttled);
    9202             :         seq_printf(sf, "throttled_time %llu\n", cfs_b->throttled_time);
    9203             : 
    9204             :         if (schedstat_enabled() && tg != &root_task_group) {
    9205             :                 u64 ws = 0;
    9206             :                 int i;
    9207             : 
    9208             :                 for_each_possible_cpu(i)
    9209             :                         ws += schedstat_val(tg->se[i]->statistics.wait_sum);
    9210             : 
    9211             :                 seq_printf(sf, "wait_sum %llu\n", ws);
    9212             :         }
    9213             : 
    9214             :         return 0;
    9215             : }
    9216             : #endif /* CONFIG_CFS_BANDWIDTH */
    9217             : #endif /* CONFIG_FAIR_GROUP_SCHED */
    9218             : 
    9219             : #ifdef CONFIG_RT_GROUP_SCHED
    9220             : static int cpu_rt_runtime_write(struct cgroup_subsys_state *css,
    9221             :                                 struct cftype *cft, s64 val)
    9222             : {
    9223             :         return sched_group_set_rt_runtime(css_tg(css), val);
    9224             : }
    9225             : 
    9226             : static s64 cpu_rt_runtime_read(struct cgroup_subsys_state *css,
    9227             :                                struct cftype *cft)
    9228             : {
    9229             :         return sched_group_rt_runtime(css_tg(css));
    9230             : }
    9231             : 
    9232             : static int cpu_rt_period_write_uint(struct cgroup_subsys_state *css,
    9233             :                                     struct cftype *cftype, u64 rt_period_us)
    9234             : {
    9235             :         return sched_group_set_rt_period(css_tg(css), rt_period_us);
    9236             : }
    9237             : 
    9238             : static u64 cpu_rt_period_read_uint(struct cgroup_subsys_state *css,
    9239             :                                    struct cftype *cft)
    9240             : {
    9241             :         return sched_group_rt_period(css_tg(css));
    9242             : }
    9243             : #endif /* CONFIG_RT_GROUP_SCHED */
    9244             : 
    9245             : static struct cftype cpu_legacy_files[] = {
    9246             : #ifdef CONFIG_FAIR_GROUP_SCHED
    9247             :         {
    9248             :                 .name = "shares",
    9249             :                 .read_u64 = cpu_shares_read_u64,
    9250             :                 .write_u64 = cpu_shares_write_u64,
    9251             :         },
    9252             : #endif
    9253             : #ifdef CONFIG_CFS_BANDWIDTH
    9254             :         {
    9255             :                 .name = "cfs_quota_us",
    9256             :                 .read_s64 = cpu_cfs_quota_read_s64,
    9257             :                 .write_s64 = cpu_cfs_quota_write_s64,
    9258             :         },
    9259             :         {
    9260             :                 .name = "cfs_period_us",
    9261             :                 .read_u64 = cpu_cfs_period_read_u64,
    9262             :                 .write_u64 = cpu_cfs_period_write_u64,
    9263             :         },
    9264             :         {
    9265             :                 .name = "stat",
    9266             :                 .seq_show = cpu_cfs_stat_show,
    9267             :         },
    9268             : #endif
    9269             : #ifdef CONFIG_RT_GROUP_SCHED
    9270             :         {
    9271             :                 .name = "rt_runtime_us",
    9272             :                 .read_s64 = cpu_rt_runtime_read,
    9273             :                 .write_s64 = cpu_rt_runtime_write,
    9274             :         },
    9275             :         {
    9276             :                 .name = "rt_period_us",
    9277             :                 .read_u64 = cpu_rt_period_read_uint,
    9278             :                 .write_u64 = cpu_rt_period_write_uint,
    9279             :         },
    9280             : #endif
    9281             : #ifdef CONFIG_UCLAMP_TASK_GROUP
    9282             :         {
    9283             :                 .name = "uclamp.min",
    9284             :                 .flags = CFTYPE_NOT_ON_ROOT,
    9285             :                 .seq_show = cpu_uclamp_min_show,
    9286             :                 .write = cpu_uclamp_min_write,
    9287             :         },
    9288             :         {
    9289             :                 .name = "uclamp.max",
    9290             :                 .flags = CFTYPE_NOT_ON_ROOT,
    9291             :                 .seq_show = cpu_uclamp_max_show,
    9292             :                 .write = cpu_uclamp_max_write,
    9293             :         },
    9294             : #endif
    9295             :         { }     /* Terminate */
    9296             : };
    9297             : 
    9298             : static int cpu_extra_stat_show(struct seq_file *sf,
    9299             :                                struct cgroup_subsys_state *css)
    9300             : {
    9301             : #ifdef CONFIG_CFS_BANDWIDTH
    9302             :         {
    9303             :                 struct task_group *tg = css_tg(css);
    9304             :                 struct cfs_bandwidth *cfs_b = &tg->cfs_bandwidth;
    9305             :                 u64 throttled_usec;
    9306             : 
    9307             :                 throttled_usec = cfs_b->throttled_time;
    9308             :                 do_div(throttled_usec, NSEC_PER_USEC);
    9309             : 
    9310             :                 seq_printf(sf, "nr_periods %d\n"
    9311             :                            "nr_throttled %d\n"
    9312             :                            "throttled_usec %llu\n",
    9313             :                            cfs_b->nr_periods, cfs_b->nr_throttled,
    9314             :                            throttled_usec);
    9315             :         }
    9316             : #endif
    9317             :         return 0;
    9318             : }
    9319             : 
    9320             : #ifdef CONFIG_FAIR_GROUP_SCHED
    9321             : static u64 cpu_weight_read_u64(struct cgroup_subsys_state *css,
    9322             :                                struct cftype *cft)
    9323             : {
    9324             :         struct task_group *tg = css_tg(css);
    9325             :         u64 weight = scale_load_down(tg->shares);
    9326             : 
    9327             :         return DIV_ROUND_CLOSEST_ULL(weight * CGROUP_WEIGHT_DFL, 1024);
    9328             : }
    9329             : 
    9330             : static int cpu_weight_write_u64(struct cgroup_subsys_state *css,
    9331             :                                 struct cftype *cft, u64 weight)
    9332             : {
    9333             :         /*
    9334             :          * cgroup weight knobs should use the common MIN, DFL and MAX
    9335             :          * values which are 1, 100 and 10000 respectively.  While it loses
    9336             :          * a bit of range on both ends, it maps pretty well onto the shares
    9337             :          * value used by scheduler and the round-trip conversions preserve
    9338             :          * the original value over the entire range.
    9339             :          */
    9340             :         if (weight < CGROUP_WEIGHT_MIN || weight > CGROUP_WEIGHT_MAX)
    9341             :                 return -ERANGE;
    9342             : 
    9343             :         weight = DIV_ROUND_CLOSEST_ULL(weight * 1024, CGROUP_WEIGHT_DFL);
    9344             : 
    9345             :         return sched_group_set_shares(css_tg(css), scale_load(weight));
    9346             : }
    9347             : 
    9348             : static s64 cpu_weight_nice_read_s64(struct cgroup_subsys_state *css,
    9349             :                                     struct cftype *cft)
    9350             : {
    9351             :         unsigned long weight = scale_load_down(css_tg(css)->shares);
    9352             :         int last_delta = INT_MAX;
    9353             :         int prio, delta;
    9354             : 
    9355             :         /* find the closest nice value to the current weight */
    9356             :         for (prio = 0; prio < ARRAY_SIZE(sched_prio_to_weight); prio++) {
    9357             :                 delta = abs(sched_prio_to_weight[prio] - weight);
    9358             :                 if (delta >= last_delta)
    9359             :                         break;
    9360             :                 last_delta = delta;
    9361             :         }
    9362             : 
    9363             :         return PRIO_TO_NICE(prio - 1 + MAX_RT_PRIO);
    9364             : }
    9365             : 
    9366             : static int cpu_weight_nice_write_s64(struct cgroup_subsys_state *css,
    9367             :                                      struct cftype *cft, s64 nice)
    9368             : {
    9369             :         unsigned long weight;
    9370             :         int idx;
    9371             : 
    9372             :         if (nice < MIN_NICE || nice > MAX_NICE)
    9373             :                 return -ERANGE;
    9374             : 
    9375             :         idx = NICE_TO_PRIO(nice) - MAX_RT_PRIO;
    9376             :         idx = array_index_nospec(idx, 40);
    9377             :         weight = sched_prio_to_weight[idx];
    9378             : 
    9379             :         return sched_group_set_shares(css_tg(css), scale_load(weight));
    9380             : }
    9381             : #endif
    9382             : 
    9383             : static void __maybe_unused cpu_period_quota_print(struct seq_file *sf,
    9384             :                                                   long period, long quota)
    9385             : {
    9386             :         if (quota < 0)
    9387             :                 seq_puts(sf, "max");
    9388             :         else
    9389             :                 seq_printf(sf, "%ld", quota);
    9390             : 
    9391             :         seq_printf(sf, " %ld\n", period);
    9392             : }
    9393             : 
    9394             : /* caller should put the current value in *@periodp before calling */
    9395             : static int __maybe_unused cpu_period_quota_parse(char *buf,
    9396             :                                                  u64 *periodp, u64 *quotap)
    9397             : {
    9398             :         char tok[21];   /* U64_MAX */
    9399             : 
    9400             :         if (sscanf(buf, "%20s %llu", tok, periodp) < 1)
    9401             :                 return -EINVAL;
    9402             : 
    9403             :         *periodp *= NSEC_PER_USEC;
    9404             : 
    9405             :         if (sscanf(tok, "%llu", quotap))
    9406             :                 *quotap *= NSEC_PER_USEC;
    9407             :         else if (!strcmp(tok, "max"))
    9408             :                 *quotap = RUNTIME_INF;
    9409             :         else
    9410             :                 return -EINVAL;
    9411             : 
    9412             :         return 0;
    9413             : }
    9414             : 
    9415             : #ifdef CONFIG_CFS_BANDWIDTH
    9416             : static int cpu_max_show(struct seq_file *sf, void *v)
    9417             : {
    9418             :         struct task_group *tg = css_tg(seq_css(sf));
    9419             : 
    9420             :         cpu_period_quota_print(sf, tg_get_cfs_period(tg), tg_get_cfs_quota(tg));
    9421             :         return 0;
    9422             : }
    9423             : 
    9424             : static ssize_t cpu_max_write(struct kernfs_open_file *of,
    9425             :                              char *buf, size_t nbytes, loff_t off)
    9426             : {
    9427             :         struct task_group *tg = css_tg(of_css(of));
    9428             :         u64 period = tg_get_cfs_period(tg);
    9429             :         u64 quota;
    9430             :         int ret;
    9431             : 
    9432             :         ret = cpu_period_quota_parse(buf, &period, &quota);
    9433             :         if (!ret)
    9434             :                 ret = tg_set_cfs_bandwidth(tg, period, quota);
    9435             :         return ret ?: nbytes;
    9436             : }
    9437             : #endif
    9438             : 
    9439             : static struct cftype cpu_files[] = {
    9440             : #ifdef CONFIG_FAIR_GROUP_SCHED
    9441             :         {
    9442             :                 .name = "weight",
    9443             :                 .flags = CFTYPE_NOT_ON_ROOT,
    9444             :                 .read_u64 = cpu_weight_read_u64,
    9445             :                 .write_u64 = cpu_weight_write_u64,
    9446             :         },
    9447             :         {
    9448             :                 .name = "weight.nice",
    9449             :                 .flags = CFTYPE_NOT_ON_ROOT,
    9450             :                 .read_s64 = cpu_weight_nice_read_s64,
    9451             :                 .write_s64 = cpu_weight_nice_write_s64,
    9452             :         },
    9453             : #endif
    9454             : #ifdef CONFIG_CFS_BANDWIDTH
    9455             :         {
    9456             :                 .name = "max",
    9457             :                 .flags = CFTYPE_NOT_ON_ROOT,
    9458             :                 .seq_show = cpu_max_show,
    9459             :                 .write = cpu_max_write,
    9460             :         },
    9461             : #endif
    9462             : #ifdef CONFIG_UCLAMP_TASK_GROUP
    9463             :         {
    9464             :                 .name = "uclamp.min",
    9465             :                 .flags = CFTYPE_NOT_ON_ROOT,
    9466             :                 .seq_show = cpu_uclamp_min_show,
    9467             :                 .write = cpu_uclamp_min_write,
    9468             :         },
    9469             :         {
    9470             :                 .name = "uclamp.max",
    9471             :                 .flags = CFTYPE_NOT_ON_ROOT,
    9472             :                 .seq_show = cpu_uclamp_max_show,
    9473             :                 .write = cpu_uclamp_max_write,
    9474             :         },
    9475             : #endif
    9476             :         { }     /* terminate */
    9477             : };
    9478             : 
    9479             : struct cgroup_subsys cpu_cgrp_subsys = {
    9480             :         .css_alloc      = cpu_cgroup_css_alloc,
    9481             :         .css_online     = cpu_cgroup_css_online,
    9482             :         .css_released   = cpu_cgroup_css_released,
    9483             :         .css_free       = cpu_cgroup_css_free,
    9484             :         .css_extra_stat_show = cpu_extra_stat_show,
    9485             :         .fork           = cpu_cgroup_fork,
    9486             :         .can_attach     = cpu_cgroup_can_attach,
    9487             :         .attach         = cpu_cgroup_attach,
    9488             :         .legacy_cftypes = cpu_legacy_files,
    9489             :         .dfl_cftypes    = cpu_files,
    9490             :         .early_init     = true,
    9491             :         .threaded       = true,
    9492             : };
    9493             : 
    9494             : #endif  /* CONFIG_CGROUP_SCHED */
    9495             : 
    9496           0 : void dump_cpu_task(int cpu)
    9497             : {
    9498           0 :         pr_info("Task dump for CPU %d:\n", cpu);
    9499           0 :         sched_show_task(cpu_curr(cpu));
    9500           0 : }
    9501             : 
    9502             : /*
    9503             :  * Nice levels are multiplicative, with a gentle 10% change for every
    9504             :  * nice level changed. I.e. when a CPU-bound task goes from nice 0 to
    9505             :  * nice 1, it will get ~10% less CPU time than another CPU-bound task
    9506             :  * that remained on nice 0.
    9507             :  *
    9508             :  * The "10% effect" is relative and cumulative: from _any_ nice level,
    9509             :  * if you go up 1 level, it's -10% CPU usage, if you go down 1 level
    9510             :  * it's +10% CPU usage. (to achieve that we use a multiplier of 1.25.
    9511             :  * If a task goes up by ~10% and another task goes down by ~10% then
    9512             :  * the relative distance between them is ~25%.)
    9513             :  */
    9514             : const int sched_prio_to_weight[40] = {
    9515             :  /* -20 */     88761,     71755,     56483,     46273,     36291,
    9516             :  /* -15 */     29154,     23254,     18705,     14949,     11916,
    9517             :  /* -10 */      9548,      7620,      6100,      4904,      3906,
    9518             :  /*  -5 */      3121,      2501,      1991,      1586,      1277,
    9519             :  /*   0 */      1024,       820,       655,       526,       423,
    9520             :  /*   5 */       335,       272,       215,       172,       137,
    9521             :  /*  10 */       110,        87,        70,        56,        45,
    9522             :  /*  15 */        36,        29,        23,        18,        15,
    9523             : };
    9524             : 
    9525             : /*
    9526             :  * Inverse (2^32/x) values of the sched_prio_to_weight[] array, precalculated.
    9527             :  *
    9528             :  * In cases where the weight does not change often, we can use the
    9529             :  * precalculated inverse to speed up arithmetics by turning divisions
    9530             :  * into multiplications:
    9531             :  */
    9532             : const u32 sched_prio_to_wmult[40] = {
    9533             :  /* -20 */     48388,     59856,     76040,     92818,    118348,
    9534             :  /* -15 */    147320,    184698,    229616,    287308,    360437,
    9535             :  /* -10 */    449829,    563644,    704093,    875809,   1099582,
    9536             :  /*  -5 */   1376151,   1717300,   2157191,   2708050,   3363326,
    9537             :  /*   0 */   4194304,   5237765,   6557202,   8165337,  10153587,
    9538             :  /*   5 */  12820798,  15790321,  19976592,  24970740,  31350126,
    9539             :  /*  10 */  39045157,  49367440,  61356676,  76695844,  95443717,
    9540             :  /*  15 */ 119304647, 148102320, 186737708, 238609294, 286331153,
    9541             : };
    9542             : 
    9543           0 : void call_trace_sched_update_nr_running(struct rq *rq, int count)
    9544             : {
    9545           0 :         trace_sched_update_nr_running_tp(rq, count);
    9546           0 : }

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