Line data    Source code

       1             : /* SPDX-License-Identifier: GPL-2.0 */
       2             : /*
       3             :  * RT Mutexes: blocking mutual exclusion locks with PI support
       4             :  *
       5             :  * started by Ingo Molnar and Thomas Gleixner:
       6             :  *
       7             :  *  Copyright (C) 2004-2006 Red Hat, Inc., Ingo Molnar <mingo@redhat.com>
       8             :  *  Copyright (C) 2006, Timesys Corp., Thomas Gleixner <tglx@timesys.com>
       9             :  *
      10             :  * This file contains the private data structure and API definitions.
      11             :  */
      12             : 
      13             : #ifndef __KERNEL_RTMUTEX_COMMON_H
      14             : #define __KERNEL_RTMUTEX_COMMON_H
      15             : 
      16             : #include <linux/rtmutex.h>
      17             : #include <linux/sched/wake_q.h>
      18             : 
      19             : /*
      20             :  * This is the control structure for tasks blocked on a rt_mutex,
      21             :  * which is allocated on the kernel stack on of the blocked task.
      22             :  *
      23             :  * @tree_entry:         pi node to enqueue into the mutex waiters tree
      24             :  * @pi_tree_entry:      pi node to enqueue into the mutex owner waiters tree
      25             :  * @task:               task reference to the blocked task
      26             :  */
      27             : struct rt_mutex_waiter {
      28             :         struct rb_node          tree_entry;
      29             :         struct rb_node          pi_tree_entry;
      30             :         struct task_struct      *task;
      31             :         struct rt_mutex         *lock;
      32             : #ifdef CONFIG_DEBUG_RT_MUTEXES
      33             :         unsigned long           ip;
      34             :         struct pid              *deadlock_task_pid;
      35             :         struct rt_mutex         *deadlock_lock;
      36             : #endif
      37             :         int prio;
      38             :         u64 deadline;
      39             : };
      40             : 
      41             : /*
      42             :  * Various helpers to access the waiters-tree:
      43             :  */
      44             : 
      45             : #ifdef CONFIG_RT_MUTEXES
      46             : 
      47           0 : static inline int rt_mutex_has_waiters(struct rt_mutex *lock)
      48             : {
      49           0 :         return !RB_EMPTY_ROOT(&lock->waiters.rb_root);
      50             : }
      51             : 
      52             : static inline struct rt_mutex_waiter *
      53           0 : rt_mutex_top_waiter(struct rt_mutex *lock)
      54             : {
      55           0 :         struct rb_node *leftmost = rb_first_cached(&lock->waiters);
      56           0 :         struct rt_mutex_waiter *w = NULL;
      57             : 
      58           0 :         if (leftmost) {
      59           0 :                 w = rb_entry(leftmost, struct rt_mutex_waiter, tree_entry);
      60           0 :                 BUG_ON(w->lock != lock);
      61             :         }
      62           0 :         return w;
      63             : }
      64             : 
      65           0 : static inline int task_has_pi_waiters(struct task_struct *p)
      66             : {
      67           0 :         return !RB_EMPTY_ROOT(&p->pi_waiters.rb_root);
      68             : }
      69             : 
      70             : static inline struct rt_mutex_waiter *
      71           0 : task_top_pi_waiter(struct task_struct *p)
      72             : {
      73           0 :         return rb_entry(p->pi_waiters.rb_leftmost,
      74             :                         struct rt_mutex_waiter, pi_tree_entry);
      75             : }
      76             : 
      77             : #else
      78             : 
      79             : static inline int rt_mutex_has_waiters(struct rt_mutex *lock)
      80             : {
      81             :         return false;
      82             : }
      83             : 
      84             : static inline struct rt_mutex_waiter *
      85             : rt_mutex_top_waiter(struct rt_mutex *lock)
      86             : {
      87             :         return NULL;
      88             : }
      89             : 
      90             : static inline int task_has_pi_waiters(struct task_struct *p)
      91             : {
      92             :         return false;
      93             : }
      94             : 
      95             : static inline struct rt_mutex_waiter *
      96             : task_top_pi_waiter(struct task_struct *p)
      97             : {
      98             :         return NULL;
      99             : }
     100             : 
     101             : #endif
     102             : 
     103             : /*
     104             :  * lock->owner state tracking:
     105             :  */
     106             : #define RT_MUTEX_HAS_WAITERS    1UL
     107             : 
     108           0 : static inline struct task_struct *rt_mutex_owner(struct rt_mutex *lock)
     109             : {
     110           0 :         unsigned long owner = (unsigned long) READ_ONCE(lock->owner);
     111             : 
     112           0 :         return (struct task_struct *) (owner & ~RT_MUTEX_HAS_WAITERS);
     113             : }
     114             : 
     115             : /*
     116             :  * Constants for rt mutex functions which have a selectable deadlock
     117             :  * detection.
     118             :  *
     119             :  * RT_MUTEX_MIN_CHAINWALK:      Stops the lock chain walk when there are
     120             :  *                              no further PI adjustments to be made.
     121             :  *
     122             :  * RT_MUTEX_FULL_CHAINWALK:     Invoke deadlock detection with a full
     123             :  *                              walk of the lock chain.
     124             :  */
     125             : enum rtmutex_chainwalk {
     126             :         RT_MUTEX_MIN_CHAINWALK,
     127             :         RT_MUTEX_FULL_CHAINWALK,
     128             : };
     129             : 
     130             : /*
     131             :  * PI-futex support (proxy locking functions, etc.):
     132             :  */
     133             : extern struct task_struct *rt_mutex_next_owner(struct rt_mutex *lock);
     134             : extern void rt_mutex_init_proxy_locked(struct rt_mutex *lock,
     135             :                                        struct task_struct *proxy_owner);
     136             : extern void rt_mutex_proxy_unlock(struct rt_mutex *lock);
     137             : extern void rt_mutex_init_waiter(struct rt_mutex_waiter *waiter);
     138             : extern int __rt_mutex_start_proxy_lock(struct rt_mutex *lock,
     139             :                                      struct rt_mutex_waiter *waiter,
     140             :                                      struct task_struct *task);
     141             : extern int rt_mutex_start_proxy_lock(struct rt_mutex *lock,
     142             :                                      struct rt_mutex_waiter *waiter,
     143             :                                      struct task_struct *task);
     144             : extern int rt_mutex_wait_proxy_lock(struct rt_mutex *lock,
     145             :                                struct hrtimer_sleeper *to,
     146             :                                struct rt_mutex_waiter *waiter);
     147             : extern bool rt_mutex_cleanup_proxy_lock(struct rt_mutex *lock,
     148             :                                  struct rt_mutex_waiter *waiter);
     149             : 
     150             : extern int rt_mutex_futex_trylock(struct rt_mutex *l);
     151             : extern int __rt_mutex_futex_trylock(struct rt_mutex *l);
     152             : 
     153             : extern void rt_mutex_futex_unlock(struct rt_mutex *lock);
     154             : extern bool __rt_mutex_futex_unlock(struct rt_mutex *lock,
     155             :                                  struct wake_q_head *wqh);
     156             : 
     157             : extern void rt_mutex_postunlock(struct wake_q_head *wake_q);
     158             : 
     159             : #ifdef CONFIG_DEBUG_RT_MUTEXES
     160             : # include "rtmutex-debug.h"
     161             : #else
     162             : # include "rtmutex.h"
     163             : #endif
     164             : 
     165             : #endif