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