kernel/irq/handle.c

   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 void handle_bad_irq(struct irq_desc *desc)
  32 {
  33         unsigned int irq = irq_desc_get_irq(desc);
  34
  35         print_irq_desc(irq, desc);
  36         kstat_incr_irqs_this_cpu(desc);
  37         ack_bad_irq(irq);
  38 }
  39 EXPORT_SYMBOL_GPL(handle_bad_irq);
  40
  41 /*
  42  * Special, empty irq handler:
  43  */
  44 irqreturn_t no_action(int cpl, void *dev_id)
  45 {
  46         return IRQ_NONE;
  47 }
  48 EXPORT_SYMBOL_GPL(no_action);
  49
  50 static void warn_no_thread(unsigned int irq, struct irqaction *action)
  51 {
  52         if (test_and_set_bit(IRQTF_WARNED, &action->thread_flags))
  53                 return;
  54
  55         printk(KERN_WARNING "IRQ %d device %s returned IRQ_WAKE_THREAD "
  56                "but no thread function available.", irq, action->name);
  57 }
  58
  59 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         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         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         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         atomic_inc(&desc->threads_active);
 133
 134         wake_up_process(action->thread);
 135 }
 136
 137 irqreturn_t __handle_irq_event_percpu(struct irq_desc *desc, unsigned int *flags)
 138 {
 139         irqreturn_t retval = IRQ_NONE;
 140         unsigned int irq = desc->irq_data.irq;
 141         struct irqaction *action;
 142
 143         record_irq_time(desc);
 144
 145         for_each_action_of_desc(desc, action) {
 146                 irqreturn_t res;
 147
 148                 trace_irq_handler_entry(irq, action);
 149                 res = action->handler(irq, action->dev_id);
 150                 trace_irq_handler_exit(irq, action, res);
 151
 152                 if (WARN_ONCE(!irqs_disabled(),"irq %u handler %pF enabled interrupts\n",
 153                               irq, action->handler))
 154                         local_irq_disable();
 155
 156                 switch (res) {
 157                 case IRQ_WAKE_THREAD:
 158                         /*
 159                          * Catch drivers which return WAKE_THREAD but
 160                          * did not set up a thread function
 161                          */
 162                         if (unlikely(!action->thread_fn)) {
 163                                 warn_no_thread(irq, action);
 164                                 break;
 165                         }
 166
 167                         __irq_wake_thread(desc, action);
 168
 169                         /* Fall through to add to randomness */
 170                 case IRQ_HANDLED:
 171                         *flags |= action->flags;
 172                         break;
 173
 174                 default:
 175                         break;
 176                 }
 177
 178                 retval |= res;
 179         }
 180
 181         return retval;
 182 }
 183
 184 irqreturn_t handle_irq_event_percpu(struct irq_desc *desc)
 185 {
 186         irqreturn_t retval;
 187         unsigned int flags = 0;
 188
 189         retval = __handle_irq_event_percpu(desc, &flags);
 190
 191         add_interrupt_randomness(desc->irq_data.irq, flags);
 192
 193         if (!noirqdebug)
 194                 note_interrupt(desc, retval);
 195         return retval;
 196 }
 197
 198 irqreturn_t handle_irq_event(struct irq_desc *desc)
 199 {
 200         irqreturn_t ret;
 201
 202         desc->istate &= ~IRQS_PENDING;
 203         irqd_set(&desc->irq_data, IRQD_IRQ_INPROGRESS);
 204         raw_spin_unlock(&desc->lock);
 205
 206         ret = handle_irq_event_percpu(desc);
 207
 208         raw_spin_lock(&desc->lock);
 209         irqd_clear(&desc->irq_data, IRQD_IRQ_INPROGRESS);
 210         return ret;
 211 }
 212
 213 #ifdef CONFIG_GENERIC_IRQ_MULTI_HANDLER
 214 int __init set_handle_irq(void (*handle_irq)(struct pt_regs *))
 215 {
 216         if (handle_arch_irq)
 217                 return -EBUSY;
 218
 219         handle_arch_irq = handle_irq;
 220         return 0;
 221 }
 222 #endif