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