Line data    Source code

       1             : // SPDX-License-Identifier: GPL-2.0
       2             : /*
       3             :  * Copyright (C) 1992, 1998-2006 Linus Torvalds, Ingo Molnar
       4             :  * Copyright (C) 2005-2006, Thomas Gleixner, Russell King
       5             :  *
       6             :  * This file contains the core interrupt handling code. Detailed
       7             :  * information is available in Documentation/core-api/genericirq.rst
       8             :  *
       9             :  */
      10             : 
      11             : #include <linux/irq.h>
      12             : #include <linux/random.h>
      13             : #include <linux/sched.h>
      14             : #include <linux/interrupt.h>
      15             : #include <linux/kernel_stat.h>
      16             : 
      17             : #include <trace/events/irq.h>
      18             : 
      19             : #include "internals.h"
      20             : 
      21             : #ifdef CONFIG_GENERIC_IRQ_MULTI_HANDLER
      22             : void (*handle_arch_irq)(struct pt_regs *) __ro_after_init;
      23             : #endif
      24             : 
      25             : /**
      26             :  * handle_bad_irq - handle spurious and unhandled irqs
      27             :  * @desc:      description of the interrupt
      28             :  *
      29             :  * Handles spurious and unhandled IRQ's. It also prints a debugmessage.
      30             :  */
      31           0 : void handle_bad_irq(struct irq_desc *desc)
      32             : {
      33           0 :         unsigned int irq = irq_desc_get_irq(desc);
      34             : 
      35           0 :         print_irq_desc(irq, desc);
      36           0 :         kstat_incr_irqs_this_cpu(desc);
      37           0 :         ack_bad_irq(irq);
      38           0 : }
      39             : EXPORT_SYMBOL_GPL(handle_bad_irq);
      40             : 
      41             : /*
      42             :  * Special, empty irq handler:
      43             :  */
      44           0 : irqreturn_t no_action(int cpl, void *dev_id)
      45             : {
      46           0 :         return IRQ_NONE;
      47             : }
      48             : EXPORT_SYMBOL_GPL(no_action);
      49             : 
      50           0 : static void warn_no_thread(unsigned int irq, struct irqaction *action)
      51             : {
      52           0 :         if (test_and_set_bit(IRQTF_WARNED, &action->thread_flags))
      53             :                 return;
      54             : 
      55           0 :         printk(KERN_WARNING "IRQ %d device %s returned IRQ_WAKE_THREAD "
      56             :                "but no thread function available.", irq, action->name);
      57             : }
      58             : 
      59           0 : void __irq_wake_thread(struct irq_desc *desc, struct irqaction *action)
      60             : {
      61             :         /*
      62             :          * In case the thread crashed and was killed we just pretend that
      63             :          * we handled the interrupt. The hardirq handler has disabled the
      64             :          * device interrupt, so no irq storm is lurking.
      65             :          */
      66           0 :         if (action->thread->flags & PF_EXITING)
      67             :                 return;
      68             : 
      69             :         /*
      70             :          * Wake up the handler thread for this action. If the
      71             :          * RUNTHREAD bit is already set, nothing to do.
      72             :          */
      73           0 :         if (test_and_set_bit(IRQTF_RUNTHREAD, &action->thread_flags))
      74             :                 return;
      75             : 
      76             :         /*
      77             :          * It's safe to OR the mask lockless here. We have only two
      78             :          * places which write to threads_oneshot: This code and the
      79             :          * irq thread.
      80             :          *
      81             :          * This code is the hard irq context and can never run on two
      82             :          * cpus in parallel. If it ever does we have more serious
      83             :          * problems than this bitmask.
      84             :          *
      85             :          * The irq threads of this irq which clear their "running" bit
      86             :          * in threads_oneshot are serialized via desc->lock against
      87             :          * each other and they are serialized against this code by
      88             :          * IRQS_INPROGRESS.
      89             :          *
      90             :          * Hard irq handler:
      91             :          *
      92             :          *      spin_lock(desc->lock);
      93             :          *      desc->state |= IRQS_INPROGRESS;
      94             :          *      spin_unlock(desc->lock);
      95             :          *      set_bit(IRQTF_RUNTHREAD, &action->thread_flags);
      96             :          *      desc->threads_oneshot |= mask;
      97             :          *      spin_lock(desc->lock);
      98             :          *      desc->state &= ~IRQS_INPROGRESS;
      99             :          *      spin_unlock(desc->lock);
     100             :          *
     101             :          * irq thread:
     102             :          *
     103             :          * again:
     104             :          *      spin_lock(desc->lock);
     105             :          *      if (desc->state & IRQS_INPROGRESS) {
     106             :          *              spin_unlock(desc->lock);
     107             :          *              while(desc->state & IRQS_INPROGRESS)
     108             :          *                      cpu_relax();
     109             :          *              goto again;
     110             :          *      }
     111             :          *      if (!test_bit(IRQTF_RUNTHREAD, &action->thread_flags))
     112             :          *              desc->threads_oneshot &= ~mask;
     113             :          *      spin_unlock(desc->lock);
     114             :          *
     115             :          * So either the thread waits for us to clear IRQS_INPROGRESS
     116             :          * or we are waiting in the flow handler for desc->lock to be
     117             :          * released before we reach this point. The thread also checks
     118             :          * IRQTF_RUNTHREAD under desc->lock. If set it leaves
     119             :          * threads_oneshot untouched and runs the thread another time.
     120             :          */
     121           0 :         desc->threads_oneshot |= action->thread_mask;
     122             : 
     123             :         /*
     124             :          * We increment the threads_active counter in case we wake up
     125             :          * the irq thread. The irq thread decrements the counter when
     126             :          * it returns from the handler or in the exit path and wakes
     127             :          * up waiters which are stuck in synchronize_irq() when the
     128             :          * active count becomes zero. synchronize_irq() is serialized
     129             :          * against this code (hard irq handler) via IRQS_INPROGRESS
     130             :          * like the finalize_oneshot() code. See comment above.
     131             :          */
     132           0 :         atomic_inc(&desc->threads_active);
     133             : 
     134           0 :         wake_up_process(action->thread);
     135             : }
     136             : 
     137        3480 : irqreturn_t __handle_irq_event_percpu(struct irq_desc *desc, unsigned int *flags)
     138             : {
     139        3480 :         irqreturn_t retval = IRQ_NONE;
     140        3480 :         unsigned int irq = desc->irq_data.irq;
     141        3480 :         struct irqaction *action;
     142             : 
     143        3480 :         record_irq_time(desc);
     144             : 
     145        6960 :         for_each_action_of_desc(desc, action) {
     146        3480 :                 irqreturn_t res;
     147             : 
     148             :                 /*
     149             :                  * If this IRQ would be threaded under force_irqthreads, mark it so.
     150             :                  */
     151        3480 :                 if (irq_settings_can_thread(desc) &&
     152        3480 :                     !(action->flags & (IRQF_NO_THREAD | IRQF_PERCPU | IRQF_ONESHOT)))
     153        3480 :                         lockdep_hardirq_threaded();
     154             : 
     155        3480 :                 trace_irq_handler_entry(irq, action);
     156        3480 :                 res = action->handler(irq, action->dev_id);
     157        3480 :                 trace_irq_handler_exit(irq, action, res);
     158             : 
     159        3480 :                 if (WARN_ONCE(!irqs_disabled(),"irq %u handler %pS enabled interrupts\n",
     160             :                               irq, action->handler))
     161           0 :                         local_irq_disable();
     162             : 
     163        3480 :                 switch (res) {
     164           0 :                 case IRQ_WAKE_THREAD:
     165             :                         /*
     166             :                          * Catch drivers which return WAKE_THREAD but
     167             :                          * did not set up a thread function
     168             :                          */
     169           0 :                         if (unlikely(!action->thread_fn)) {
     170           0 :                                 warn_no_thread(irq, action);
     171           0 :                                 break;
     172             :                         }
     173             : 
     174           0 :                         __irq_wake_thread(desc, action);
     175             : 
     176        3241 :                         fallthrough;    /* to add to randomness */
     177        3241 :                 case IRQ_HANDLED:
     178        3241 :                         *flags |= action->flags;
     179        3241 :                         break;
     180             : 
     181             :                 default:
     182             :                         break;
     183             :                 }
     184             : 
     185        3480 :                 retval |= res;
     186             :         }
     187             : 
     188        3480 :         return retval;
     189             : }
     190             : 
     191        3480 : irqreturn_t handle_irq_event_percpu(struct irq_desc *desc)
     192             : {
     193        3480 :         irqreturn_t retval;
     194        3480 :         unsigned int flags = 0;
     195             : 
     196        3480 :         retval = __handle_irq_event_percpu(desc, &flags);
     197             : 
     198        3480 :         add_interrupt_randomness(desc->irq_data.irq, flags);
     199             : 
     200        3480 :         if (!noirqdebug)
     201        3480 :                 note_interrupt(desc, retval);
     202        3480 :         return retval;
     203             : }
     204             : 
     205        3480 : irqreturn_t handle_irq_event(struct irq_desc *desc)
     206             : {
     207        3480 :         irqreturn_t ret;
     208             : 
     209        3480 :         desc->istate &= ~IRQS_PENDING;
     210        3480 :         irqd_set(&desc->irq_data, IRQD_IRQ_INPROGRESS);
     211        3480 :         raw_spin_unlock(&desc->lock);
     212             : 
     213        3480 :         ret = handle_irq_event_percpu(desc);
     214             : 
     215        3480 :         raw_spin_lock(&desc->lock);
     216        3480 :         irqd_clear(&desc->irq_data, IRQD_IRQ_INPROGRESS);
     217        3480 :         return ret;
     218             : }
     219             : 
     220             : #ifdef CONFIG_GENERIC_IRQ_MULTI_HANDLER
     221             : int __init set_handle_irq(void (*handle_irq)(struct pt_regs *))
     222             : {
     223             :         if (handle_arch_irq)
     224             :                 return -EBUSY;
     225             : 
     226             :         handle_arch_irq = handle_irq;
     227             :         return 0;
     228             : }
     229             : #endif