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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 * @desc: description of the interrupt
26 *
27 * Handles spurious and unhandled IRQ's. It also prints a debugmessage.
28 */
29void 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}
37EXPORT_SYMBOL_GPL(handle_bad_irq);
38
39/*
40 * Special, empty irq handler:
41 */
42irqreturn_t no_action(int cpl, void *dev_id)
43{
44 return IRQ_NONE;
45}
46EXPORT_SYMBOL_GPL(no_action);
47
48static 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
57void __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
135irqreturn_t handle_irq_event_percpu(struct irq_desc *desc)
136{
137 irqreturn_t retval = IRQ_NONE;
138 unsigned int flags = 0, irq = desc->irq_data.irq;
139 struct irqaction *action;
140
141 for_each_action_of_desc(desc, action) {
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 }
176
177 add_interrupt_randomness(irq, flags);
178
179 if (!noirqdebug)
180 note_interrupt(desc, retval);
181 return retval;
182}
183
184irqreturn_t handle_irq_event(struct irq_desc *desc)
185{
186 irqreturn_t ret;
187
188 desc->istate &= ~IRQS_PENDING;
189 irqd_set(&desc->irq_data, IRQD_IRQ_INPROGRESS);
190 raw_spin_unlock(&desc->lock);
191
192 ret = handle_irq_event_percpu(desc);
193
194 raw_spin_lock(&desc->lock);
195 irqd_clear(&desc->irq_data, IRQD_IRQ_INPROGRESS);
196 return ret;
197}
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 */
30void 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 */
40irqreturn_t no_action(int cpl, void *dev_id)
41{
42 return IRQ_NONE;
43}
44EXPORT_SYMBOL_GPL(no_action);
45
46static void warn_no_thread(unsigned int irq, struct irqaction *action)
47{
48 if (test_and_set_bit(IRQTF_WARNED, &action->thread_flags))
49 return;
50
51 printk(KERN_WARNING "IRQ %d device %s returned IRQ_WAKE_THREAD "
52 "but no thread function available.", irq, action->name);
53}
54
55void __irq_wake_thread(struct irq_desc *desc, struct irqaction *action)
56{
57 /*
58 * In case the thread crashed and was killed we just pretend that
59 * we handled the interrupt. The hardirq handler has disabled the
60 * device interrupt, so no irq storm is lurking.
61 */
62 if (action->thread->flags & PF_EXITING)
63 return;
64
65 /*
66 * Wake up the handler thread for this action. If the
67 * RUNTHREAD bit is already set, nothing to do.
68 */
69 if (test_and_set_bit(IRQTF_RUNTHREAD, &action->thread_flags))
70 return;
71
72 /*
73 * It's safe to OR the mask lockless here. We have only two
74 * places which write to threads_oneshot: This code and the
75 * irq thread.
76 *
77 * This code is the hard irq context and can never run on two
78 * cpus in parallel. If it ever does we have more serious
79 * problems than this bitmask.
80 *
81 * The irq threads of this irq which clear their "running" bit
82 * in threads_oneshot are serialized via desc->lock against
83 * each other and they are serialized against this code by
84 * IRQS_INPROGRESS.
85 *
86 * Hard irq handler:
87 *
88 * spin_lock(desc->lock);
89 * desc->state |= IRQS_INPROGRESS;
90 * spin_unlock(desc->lock);
91 * set_bit(IRQTF_RUNTHREAD, &action->thread_flags);
92 * desc->threads_oneshot |= mask;
93 * spin_lock(desc->lock);
94 * desc->state &= ~IRQS_INPROGRESS;
95 * spin_unlock(desc->lock);
96 *
97 * irq thread:
98 *
99 * again:
100 * spin_lock(desc->lock);
101 * if (desc->state & IRQS_INPROGRESS) {
102 * spin_unlock(desc->lock);
103 * while(desc->state & IRQS_INPROGRESS)
104 * cpu_relax();
105 * goto again;
106 * }
107 * if (!test_bit(IRQTF_RUNTHREAD, &action->thread_flags))
108 * desc->threads_oneshot &= ~mask;
109 * spin_unlock(desc->lock);
110 *
111 * So either the thread waits for us to clear IRQS_INPROGRESS
112 * or we are waiting in the flow handler for desc->lock to be
113 * released before we reach this point. The thread also checks
114 * IRQTF_RUNTHREAD under desc->lock. If set it leaves
115 * threads_oneshot untouched and runs the thread another time.
116 */
117 desc->threads_oneshot |= action->thread_mask;
118
119 /*
120 * We increment the threads_active counter in case we wake up
121 * the irq thread. The irq thread decrements the counter when
122 * it returns from the handler or in the exit path and wakes
123 * up waiters which are stuck in synchronize_irq() when the
124 * active count becomes zero. synchronize_irq() is serialized
125 * against this code (hard irq handler) via IRQS_INPROGRESS
126 * like the finalize_oneshot() code. See comment above.
127 */
128 atomic_inc(&desc->threads_active);
129
130 wake_up_process(action->thread);
131}
132
133irqreturn_t
134handle_irq_event_percpu(struct irq_desc *desc, struct irqaction *action)
135{
136 irqreturn_t retval = IRQ_NONE;
137 unsigned int flags = 0, irq = desc->irq_data.irq;
138
139 do {
140 irqreturn_t res;
141
142 trace_irq_handler_entry(irq, action);
143 res = action->handler(irq, action->dev_id);
144 trace_irq_handler_exit(irq, action, res);
145
146 if (WARN_ONCE(!irqs_disabled(),"irq %u handler %pF enabled interrupts\n",
147 irq, action->handler))
148 local_irq_disable();
149
150 switch (res) {
151 case IRQ_WAKE_THREAD:
152 /*
153 * Catch drivers which return WAKE_THREAD but
154 * did not set up a thread function
155 */
156 if (unlikely(!action->thread_fn)) {
157 warn_no_thread(irq, action);
158 break;
159 }
160
161 __irq_wake_thread(desc, action);
162
163 /* Fall through to add to randomness */
164 case IRQ_HANDLED:
165 flags |= action->flags;
166 break;
167
168 default:
169 break;
170 }
171
172 retval |= res;
173 action = action->next;
174 } while (action);
175
176 add_interrupt_randomness(irq, flags);
177
178 if (!noirqdebug)
179 note_interrupt(irq, desc, retval);
180 return retval;
181}
182
183irqreturn_t handle_irq_event(struct irq_desc *desc)
184{
185 struct irqaction *action = desc->action;
186 irqreturn_t ret;
187
188 desc->istate &= ~IRQS_PENDING;
189 irqd_set(&desc->irq_data, IRQD_IRQ_INPROGRESS);
190 raw_spin_unlock(&desc->lock);
191
192 ret = handle_irq_event_percpu(desc, action);
193
194 raw_spin_lock(&desc->lock);
195 irqd_clear(&desc->irq_data, IRQD_IRQ_INPROGRESS);
196 return ret;
197}