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