Add linux-next specific files for 20110824
[linux-2.6/next.git] / kernel / irq / handle.c
blob470d08c82bbe29f373a9aa79d07794d56985763b
1 /*
2 * linux/kernel/irq/handle.c
4 * Copyright (C) 1992, 1998-2006 Linus Torvalds, Ingo Molnar
5 * Copyright (C) 2005-2006, Thomas Gleixner, Russell King
7 * This file contains the core interrupt handling code.
9 * Detailed information is available in Documentation/DocBook/genericirq
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>
19 #include <trace/events/irq.h>
21 #include "internals.h"
23 /**
24 * handle_bad_irq - handle spurious and unhandled irqs
25 * @irq: the interrupt number
26 * @desc: description of the interrupt
28 * Handles spurious and unhandled IRQ's. It also prints a debugmessage.
30 void handle_bad_irq(unsigned int irq, struct irq_desc *desc)
32 print_irq_desc(irq, desc);
33 kstat_incr_irqs_this_cpu(irq, desc);
34 ack_bad_irq(irq);
38 * Special, empty irq handler:
40 irqreturn_t no_action(int cpl, void *dev_id)
42 return IRQ_NONE;
45 static void warn_no_thread(unsigned int irq, struct irqaction *action)
47 if (test_and_set_bit(IRQTF_WARNED, &action->thread_flags))
48 return;
50 printk(KERN_WARNING "IRQ %d device %s returned IRQ_WAKE_THREAD "
51 "but no thread function available.", irq, action->name);
54 static void irq_wake_thread(struct irq_desc *desc, struct irqaction *action)
57 * Wake up the handler thread for this action. In case the
58 * thread crashed and was killed we just pretend that we
59 * handled the interrupt. The hardirq handler has disabled the
60 * device interrupt, so no irq storm is lurking. If the
61 * RUNTHREAD bit is already set, nothing to do.
63 if (test_bit(IRQTF_DIED, &action->thread_flags) ||
64 test_and_set_bit(IRQTF_RUNTHREAD, &action->thread_flags))
65 return;
68 * It's safe to OR the mask lockless here. We have only two
69 * places which write to threads_oneshot: This code and the
70 * irq thread.
72 * This code is the hard irq context and can never run on two
73 * cpus in parallel. If it ever does we have more serious
74 * problems than this bitmask.
76 * The irq threads of this irq which clear their "running" bit
77 * in threads_oneshot are serialized via desc->lock against
78 * each other and they are serialized against this code by
79 * IRQS_INPROGRESS.
81 * Hard irq handler:
83 * spin_lock(desc->lock);
84 * desc->state |= IRQS_INPROGRESS;
85 * spin_unlock(desc->lock);
86 * set_bit(IRQTF_RUNTHREAD, &action->thread_flags);
87 * desc->threads_oneshot |= mask;
88 * spin_lock(desc->lock);
89 * desc->state &= ~IRQS_INPROGRESS;
90 * spin_unlock(desc->lock);
92 * irq thread:
94 * again:
95 * spin_lock(desc->lock);
96 * if (desc->state & IRQS_INPROGRESS) {
97 * spin_unlock(desc->lock);
98 * while(desc->state & IRQS_INPROGRESS)
99 * cpu_relax();
100 * goto again;
102 * if (!test_bit(IRQTF_RUNTHREAD, &action->thread_flags))
103 * desc->threads_oneshot &= ~mask;
104 * spin_unlock(desc->lock);
106 * So either the thread waits for us to clear IRQS_INPROGRESS
107 * or we are waiting in the flow handler for desc->lock to be
108 * released before we reach this point. The thread also checks
109 * IRQTF_RUNTHREAD under desc->lock. If set it leaves
110 * threads_oneshot untouched and runs the thread another time.
112 desc->threads_oneshot |= action->thread_mask;
113 wake_up_process(action->thread);
116 irqreturn_t
117 handle_irq_event_percpu(struct irq_desc *desc, struct irqaction *action)
119 irqreturn_t retval = IRQ_NONE;
120 unsigned int random = 0, irq = desc->irq_data.irq;
122 do {
123 irqreturn_t res;
125 trace_irq_handler_entry(irq, action);
126 res = action->handler(irq, action->dev_id);
127 trace_irq_handler_exit(irq, action, res);
129 if (WARN_ONCE(!irqs_disabled(),"irq %u handler %pF enabled interrupts\n",
130 irq, action->handler))
131 local_irq_disable();
133 switch (res) {
134 case IRQ_WAKE_THREAD:
136 * Catch drivers which return WAKE_THREAD but
137 * did not set up a thread function
139 if (unlikely(!action->thread_fn)) {
140 warn_no_thread(irq, action);
141 break;
144 irq_wake_thread(desc, action);
146 /* Fall through to add to randomness */
147 case IRQ_HANDLED:
148 random |= action->flags;
149 break;
151 default:
152 break;
155 retval |= res;
156 action = action->next;
157 } while (action);
159 if (random & IRQF_SAMPLE_RANDOM)
160 add_interrupt_randomness(irq);
162 if (!noirqdebug)
163 note_interrupt(irq, desc, retval);
164 return retval;
167 irqreturn_t handle_irq_event(struct irq_desc *desc)
169 struct irqaction *action = desc->action;
170 irqreturn_t ret;
172 desc->istate &= ~IRQS_PENDING;
173 irqd_set(&desc->irq_data, IRQD_IRQ_INPROGRESS);
174 raw_spin_unlock(&desc->lock);
176 ret = handle_irq_event_percpu(desc, action);
178 raw_spin_lock(&desc->lock);
179 irqd_clear(&desc->irq_data, IRQD_IRQ_INPROGRESS);
180 return ret;