1 // SPDX-License-Identifier: GPL-2.0 2 /* 3 * Copyright (C) 1992, 1998-2006 Linus Torvalds, Ingo Molnar 4 * Copyright (C) 2005-2006, Thomas Gleixner, Russell King 5 * 6 * This file contains the core interrupt handling code. Detailed 7 * information is available in Documentation/core-api/genericirq.rst 8 * 9 */ 10 11 #include <linux/irq.h> 12 #include <linux/random.h> 13 #include <linux/sched.h> 14 #include <linux/interrupt.h> 15 #include <linux/kernel_stat.h> 16 17 #include <trace/events/irq.h> 18 19 #include "internals.h" 20 21 #ifdef CONFIG_GENERIC_IRQ_MULTI_HANDLER 22 void (*handle_arch_irq)(struct pt_regs *) __ro_after_init; 23 #endif 24 25 /** 26 * handle_bad_irq - handle spurious and unhandled irqs 27 * @desc: description of the interrupt 28 * 29 * Handles spurious and unhandled IRQ's. It also prints a debugmessage. 30 */ 31 void handle_bad_irq(struct irq_desc *desc) 32 { 33 unsigned int irq = irq_desc_get_irq(desc); 34 35 print_irq_desc(irq, desc); 36 kstat_incr_irqs_this_cpu(desc); 37 ack_bad_irq(irq); 38 } 39 EXPORT_SYMBOL_GPL(handle_bad_irq); 40 41 /* 42 * Special, empty irq handler: 43 */ 44 irqreturn_t no_action(int cpl, void *dev_id) 45 { 46 return IRQ_NONE; 47 } 48 EXPORT_SYMBOL_GPL(no_action); 49 50 static void warn_no_thread(unsigned int irq, struct irqaction *action) 51 { 52 if (test_and_set_bit(IRQTF_WARNED, &action->thread_flags)) 53 return; 54 55 printk(KERN_WARNING "IRQ %d device %s returned IRQ_WAKE_THREAD " 56 "but no thread function available.", irq, action->name); 57 } 58 59 void __irq_wake_thread(struct irq_desc *desc, struct irqaction *action) 60 { 61 /* 62 * In case the thread crashed and was killed we just pretend that 63 * we handled the interrupt. The hardirq handler has disabled the 64 * device interrupt, so no irq storm is lurking. 65 */ 66 if (action->thread->flags & PF_EXITING) 67 return; 68 69 /* 70 * Wake up the handler thread for this action. If the 71 * RUNTHREAD bit is already set, nothing to do. 72 */ 73 if (test_and_set_bit(IRQTF_RUNTHREAD, &action->thread_flags)) 74 return; 75 76 /* 77 * It's safe to OR the mask lockless here. We have only two 78 * places which write to threads_oneshot: This code and the 79 * irq thread. 80 * 81 * This code is the hard irq context and can never run on two 82 * cpus in parallel. If it ever does we have more serious 83 * problems than this bitmask. 84 * 85 * The irq threads of this irq which clear their "running" bit 86 * in threads_oneshot are serialized via desc->lock against 87 * each other and they are serialized against this code by 88 * IRQS_INPROGRESS. 89 * 90 * Hard irq handler: 91 * 92 * spin_lock(desc->lock); 93 * desc->state |= IRQS_INPROGRESS; 94 * spin_unlock(desc->lock); 95 * set_bit(IRQTF_RUNTHREAD, &action->thread_flags); 96 * desc->threads_oneshot |= mask; 97 * spin_lock(desc->lock); 98 * desc->state &= ~IRQS_INPROGRESS; 99 * spin_unlock(desc->lock); 100 * 101 * irq thread: 102 * 103 * again: 104 * spin_lock(desc->lock); 105 * if (desc->state & IRQS_INPROGRESS) { 106 * spin_unlock(desc->lock); 107 * while(desc->state & IRQS_INPROGRESS) 108 * cpu_relax(); 109 * goto again; 110 * } 111 * if (!test_bit(IRQTF_RUNTHREAD, &action->thread_flags)) 112 * desc->threads_oneshot &= ~mask; 113 * spin_unlock(desc->lock); 114 * 115 * So either the thread waits for us to clear IRQS_INPROGRESS 116 * or we are waiting in the flow handler for desc->lock to be 117 * released before we reach this point. The thread also checks 118 * IRQTF_RUNTHREAD under desc->lock. If set it leaves 119 * threads_oneshot untouched and runs the thread another time. 120 */ 121 desc->threads_oneshot |= action->thread_mask; 122 123 /* 124 * We increment the threads_active counter in case we wake up 125 * the irq thread. The irq thread decrements the counter when 126 * it returns from the handler or in the exit path and wakes 127 * up waiters which are stuck in synchronize_irq() when the 128 * active count becomes zero. synchronize_irq() is serialized 129 * against this code (hard irq handler) via IRQS_INPROGRESS 130 * like the finalize_oneshot() code. See comment above. 131 */ 132 atomic_inc(&desc->threads_active); 133 134 wake_up_process(action->thread); 135 } 136 137 irqreturn_t __handle_irq_event_percpu(struct irq_desc *desc, unsigned int *flags) 138 { 139 irqreturn_t retval = IRQ_NONE; 140 unsigned int irq = desc->irq_data.irq; 141 struct irqaction *action; 142 143 record_irq_time(desc); 144 145 for_each_action_of_desc(desc, action) { 146 irqreturn_t res; 147 148 trace_irq_handler_entry(irq, action); 149 res = action->handler(irq, action->dev_id); 150 trace_irq_handler_exit(irq, action, res); 151 152 if (WARN_ONCE(!irqs_disabled(),"irq %u handler %pS enabled interrupts\n", 153 irq, action->handler)) 154 local_irq_disable(); 155 156 switch (res) { 157 case IRQ_WAKE_THREAD: 158 /* 159 * Catch drivers which return WAKE_THREAD but 160 * did not set up a thread function 161 */ 162 if (unlikely(!action->thread_fn)) { 163 warn_no_thread(irq, action); 164 break; 165 } 166 167 __irq_wake_thread(desc, action); 168 169 /* Fall through - to add to randomness */ 170 case IRQ_HANDLED: 171 *flags |= action->flags; 172 break; 173 174 default: 175 break; 176 } 177 178 retval |= res; 179 } 180 181 return retval; 182 } 183 184 irqreturn_t handle_irq_event_percpu(struct irq_desc *desc) 185 { 186 irqreturn_t retval; 187 unsigned int flags = 0; 188 189 retval = __handle_irq_event_percpu(desc, &flags); 190 191 add_interrupt_randomness(desc->irq_data.irq, flags); 192 193 if (!noirqdebug) 194 note_interrupt(desc, retval); 195 return retval; 196 } 197 198 irqreturn_t handle_irq_event(struct irq_desc *desc) 199 { 200 irqreturn_t ret; 201 202 desc->istate &= ~IRQS_PENDING; 203 irqd_set(&desc->irq_data, IRQD_IRQ_INPROGRESS); 204 raw_spin_unlock(&desc->lock); 205 206 ret = handle_irq_event_percpu(desc); 207 208 raw_spin_lock(&desc->lock); 209 irqd_clear(&desc->irq_data, IRQD_IRQ_INPROGRESS); 210 return ret; 211 } 212 213 #ifdef CONFIG_GENERIC_IRQ_MULTI_HANDLER 214 int __init set_handle_irq(void (*handle_irq)(struct pt_regs *)) 215 { 216 if (handle_arch_irq) 217 return -EBUSY; 218 219 handle_arch_irq = handle_irq; 220 return 0; 221 } 222 #endif 223