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/core-api/genericirq.rst 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 * @desc: description of the interrupt 26 * 27 * Handles spurious and unhandled IRQ's. It also prints a debugmessage. 28 */ 29 void handle_bad_irq(struct irq_desc *desc) 30 { 31 unsigned int irq = irq_desc_get_irq(desc); 32 33 print_irq_desc(irq, desc); 34 kstat_incr_irqs_this_cpu(desc); 35 ack_bad_irq(irq); 36 } 37 EXPORT_SYMBOL_GPL(handle_bad_irq); 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 __handle_irq_event_percpu(struct irq_desc *desc, unsigned int *flags) 136 { 137 irqreturn_t retval = IRQ_NONE; 138 unsigned int irq = desc->irq_data.irq; 139 struct irqaction *action; 140 141 record_irq_time(desc); 142 143 for_each_action_of_desc(desc, action) { 144 irqreturn_t res; 145 146 trace_irq_handler_entry(irq, action); 147 res = action->handler(irq, action->dev_id); 148 trace_irq_handler_exit(irq, action, res); 149 150 if (WARN_ONCE(!irqs_disabled(),"irq %u handler %pF enabled interrupts\n", 151 irq, action->handler)) 152 local_irq_disable(); 153 154 switch (res) { 155 case IRQ_WAKE_THREAD: 156 /* 157 * Catch drivers which return WAKE_THREAD but 158 * did not set up a thread function 159 */ 160 if (unlikely(!action->thread_fn)) { 161 warn_no_thread(irq, action); 162 break; 163 } 164 165 __irq_wake_thread(desc, action); 166 167 /* Fall through to add to randomness */ 168 case IRQ_HANDLED: 169 *flags |= action->flags; 170 break; 171 172 default: 173 break; 174 } 175 176 retval |= res; 177 } 178 179 return retval; 180 } 181 182 irqreturn_t handle_irq_event_percpu(struct irq_desc *desc) 183 { 184 irqreturn_t retval; 185 unsigned int flags = 0; 186 187 retval = __handle_irq_event_percpu(desc, &flags); 188 189 add_interrupt_randomness(desc->irq_data.irq, flags); 190 191 if (!noirqdebug) 192 note_interrupt(desc, retval); 193 return retval; 194 } 195 196 irqreturn_t handle_irq_event(struct irq_desc *desc) 197 { 198 irqreturn_t ret; 199 200 desc->istate &= ~IRQS_PENDING; 201 irqd_set(&desc->irq_data, IRQD_IRQ_INPROGRESS); 202 raw_spin_unlock(&desc->lock); 203 204 ret = handle_irq_event_percpu(desc); 205 206 raw_spin_lock(&desc->lock); 207 irqd_clear(&desc->irq_data, IRQD_IRQ_INPROGRESS); 208 return ret; 209 } 210