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 } 200