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