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 */
handle_bad_irq(unsigned int irq,struct irq_desc * desc)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 */
no_action(int cpl,void * dev_id)40 irqreturn_t no_action(int cpl, void *dev_id)
41 {
42 return IRQ_NONE;
43 }
44
warn_no_thread(unsigned int irq,struct irqaction * action)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
irq_wake_thread(struct irq_desc * desc,struct irqaction * action)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
handle_irq_event_percpu(struct irq_desc * desc,struct irqaction * action)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
handle_irq_event(struct irq_desc * desc)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