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