kernel/irq/handle.c

0001 // SPDX-License-Identifier: GPL-2.0
0002 /*
0003  * Copyright (C) 1992, 1998-2006 Linus Torvalds, Ingo Molnar
0004  * Copyright (C) 2005-2006, Thomas Gleixner, Russell King
0005  *
0006  * This file contains the core interrupt handling code. Detailed
0007  * information is available in Documentation/core-api/genericirq.rst
0008  *
0009  */
0010
0011 #include <linux/irq.h>
0012 #include <linux/random.h>
0013 #include <linux/sched.h>
0014 #include <linux/interrupt.h>
0015 #include <linux/kernel_stat.h>
0016
0017 #include <asm/irq_regs.h>
0018
0019 #include <trace/events/irq.h>
0020
0021 #include "internals.h"
0022
0023 #ifdef CONFIG_GENERIC_IRQ_MULTI_HANDLER
0024 void (*handle_arch_irq)(struct pt_regs *) __ro_after_init;
0025 #endif
0026
0027 /**
0028  * handle_bad_irq - handle spurious and unhandled irqs
0029  * @desc:      description of the interrupt
0030  *
0031  * Handles spurious and unhandled IRQ's. It also prints a debugmessage.
0032  */
0033 void handle_bad_irq(struct irq_desc *desc)
0034 {
0035     unsigned int irq = irq_desc_get_irq(desc);
0036
0037     print_irq_desc(irq, desc);
0038     kstat_incr_irqs_this_cpu(desc);
0039     ack_bad_irq(irq);
0040 }
0041 EXPORT_SYMBOL_GPL(handle_bad_irq);
0042
0043 /*
0044  * Special, empty irq handler:
0045  */
0046 irqreturn_t no_action(int cpl, void *dev_id)
0047 {
0048     return IRQ_NONE;
0049 }
0050 EXPORT_SYMBOL_GPL(no_action);
0051
0052 static void warn_no_thread(unsigned int irq, struct irqaction *action)
0053 {
0054     if (test_and_set_bit(IRQTF_WARNED, &action->thread_flags))
0055         return;
0056
0057     printk(KERN_WARNING "IRQ %d device %s returned IRQ_WAKE_THREAD "
0058            "but no thread function available.", irq, action->name);
0059 }
0060
0061 void __irq_wake_thread(struct irq_desc *desc, struct irqaction *action)
0062 {
0063     /*
0064      * In case the thread crashed and was killed we just pretend that
0065      * we handled the interrupt. The hardirq handler has disabled the
0066      * device interrupt, so no irq storm is lurking.
0067      */
0068     if (action->thread->flags & PF_EXITING)
0069         return;
0070
0071     /*
0072      * Wake up the handler thread for this action. If the
0073      * RUNTHREAD bit is already set, nothing to do.
0074      */
0075     if (test_and_set_bit(IRQTF_RUNTHREAD, &action->thread_flags))
0076         return;
0077
0078     /*
0079      * It's safe to OR the mask lockless here. We have only two
0080      * places which write to threads_oneshot: This code and the
0081      * irq thread.
0082      *
0083      * This code is the hard irq context and can never run on two
0084      * cpus in parallel. If it ever does we have more serious
0085      * problems than this bitmask.
0086      *
0087      * The irq threads of this irq which clear their "running" bit
0088      * in threads_oneshot are serialized via desc->lock against
0089      * each other and they are serialized against this code by
0090      * IRQS_INPROGRESS.
0091      *
0092      * Hard irq handler:
0093      *
0094      *  spin_lock(desc->lock);
0095      *  desc->state |= IRQS_INPROGRESS;
0096      *  spin_unlock(desc->lock);
0097      *  set_bit(IRQTF_RUNTHREAD, &action->thread_flags);
0098      *  desc->threads_oneshot |= mask;
0099      *  spin_lock(desc->lock);
0100      *  desc->state &= ~IRQS_INPROGRESS;
0101      *  spin_unlock(desc->lock);
0102      *
0103      * irq thread:
0104      *
0105      * again:
0106      *  spin_lock(desc->lock);
0107      *  if (desc->state & IRQS_INPROGRESS) {
0108      *      spin_unlock(desc->lock);
0109      *      while(desc->state & IRQS_INPROGRESS)
0110      *          cpu_relax();
0111      *      goto again;
0112      *  }
0113      *  if (!test_bit(IRQTF_RUNTHREAD, &action->thread_flags))
0114      *      desc->threads_oneshot &= ~mask;
0115      *  spin_unlock(desc->lock);
0116      *
0117      * So either the thread waits for us to clear IRQS_INPROGRESS
0118      * or we are waiting in the flow handler for desc->lock to be
0119      * released before we reach this point. The thread also checks
0120      * IRQTF_RUNTHREAD under desc->lock. If set it leaves
0121      * threads_oneshot untouched and runs the thread another time.
0122      */
0123     desc->threads_oneshot |= action->thread_mask;
0124
0125     /*
0126      * We increment the threads_active counter in case we wake up
0127      * the irq thread. The irq thread decrements the counter when
0128      * it returns from the handler or in the exit path and wakes
0129      * up waiters which are stuck in synchronize_irq() when the
0130      * active count becomes zero. synchronize_irq() is serialized
0131      * against this code (hard irq handler) via IRQS_INPROGRESS
0132      * like the finalize_oneshot() code. See comment above.
0133      */
0134     atomic_inc(&desc->threads_active);
0135
0136     wake_up_process(action->thread);
0137 }
0138
0139 irqreturn_t __handle_irq_event_percpu(struct irq_desc *desc)
0140 {
0141     irqreturn_t retval = IRQ_NONE;
0142     unsigned int irq = desc->irq_data.irq;
0143     struct irqaction *action;
0144
0145     record_irq_time(desc);
0146
0147     for_each_action_of_desc(desc, action) {
0148         irqreturn_t res;
0149
0150         /*
0151          * If this IRQ would be threaded under force_irqthreads, mark it so.
0152          */
0153         if (irq_settings_can_thread(desc) &&
0154             !(action->flags & (IRQF_NO_THREAD | IRQF_PERCPU | IRQF_ONESHOT)))
0155             lockdep_hardirq_threaded();
0156
0157         trace_irq_handler_entry(irq, action);
0158         res = action->handler(irq, action->dev_id);
0159         trace_irq_handler_exit(irq, action, res);
0160
0161         if (WARN_ONCE(!irqs_disabled(),"irq %u handler %pS enabled interrupts\n",
0162                   irq, action->handler))
0163             local_irq_disable();
0164
0165         switch (res) {
0166         case IRQ_WAKE_THREAD:
0167             /*
0168              * Catch drivers which return WAKE_THREAD but
0169              * did not set up a thread function
0170              */
0171             if (unlikely(!action->thread_fn)) {
0172                 warn_no_thread(irq, action);
0173                 break;
0174             }
0175
0176             __irq_wake_thread(desc, action);
0177             break;
0178
0179         default:
0180             break;
0181         }
0182
0183         retval |= res;
0184     }
0185
0186     return retval;
0187 }
0188
0189 irqreturn_t handle_irq_event_percpu(struct irq_desc *desc)
0190 {
0191     irqreturn_t retval;
0192
0193     retval = __handle_irq_event_percpu(desc);
0194
0195     add_interrupt_randomness(desc->irq_data.irq);
0196
0197     if (!irq_settings_no_debug(desc))
0198         note_interrupt(desc, retval);
0199     return retval;
0200 }
0201
0202 irqreturn_t handle_irq_event(struct irq_desc *desc)
0203 {
0204     irqreturn_t ret;
0205
0206     desc->istate &= ~IRQS_PENDING;
0207     irqd_set(&desc->irq_data, IRQD_IRQ_INPROGRESS);
0208     raw_spin_unlock(&desc->lock);
0209
0210     ret = handle_irq_event_percpu(desc);
0211
0212     raw_spin_lock(&desc->lock);
0213     irqd_clear(&desc->irq_data, IRQD_IRQ_INPROGRESS);
0214     return ret;
0215 }
0216
0217 #ifdef CONFIG_GENERIC_IRQ_MULTI_HANDLER
0218 int __init set_handle_irq(void (*handle_irq)(struct pt_regs *))
0219 {
0220     if (handle_arch_irq)
0221         return -EBUSY;
0222
0223     handle_arch_irq = handle_irq;
0224     return 0;
0225 }
0226
0227 /**
0228  * generic_handle_arch_irq - root irq handler for architectures which do no
0229  *                           entry accounting themselves
0230  * @regs:   Register file coming from the low-level handling code
0231  */
0232 asmlinkage void noinstr generic_handle_arch_irq(struct pt_regs *regs)
0233 {
0234     struct pt_regs *old_regs;
0235
0236     irq_enter();
0237     old_regs = set_irq_regs(regs);
0238     handle_arch_irq(regs);
0239     set_irq_regs(old_regs);
0240     irq_exit();
0241 }
0242 #endif