Root/kernel/irq/spurious.c

1/*
2 * linux/kernel/irq/spurious.c
3 *
4 * Copyright (C) 1992, 1998-2004 Linus Torvalds, Ingo Molnar
5 *
6 * This file contains spurious interrupt handling.
7 */
8
9#include <linux/jiffies.h>
10#include <linux/irq.h>
11#include <linux/module.h>
12#include <linux/kallsyms.h>
13#include <linux/interrupt.h>
14#include <linux/moduleparam.h>
15#include <linux/timer.h>
16
17#include "internals.h"
18
19static int irqfixup __read_mostly;
20
21#define POLL_SPURIOUS_IRQ_INTERVAL (HZ/10)
22static void poll_spurious_irqs(unsigned long dummy);
23static DEFINE_TIMER(poll_spurious_irq_timer, poll_spurious_irqs, 0, 0);
24
25/*
26 * Recovery handler for misrouted interrupts.
27 */
28static int try_one_irq(int irq, struct irq_desc *desc)
29{
30    struct irqaction *action;
31    int ok = 0, work = 0;
32
33    raw_spin_lock(&desc->lock);
34    /* Already running on another processor */
35    if (desc->status & IRQ_INPROGRESS) {
36        /*
37         * Already running: If it is shared get the other
38         * CPU to go looking for our mystery interrupt too
39         */
40        if (desc->action && (desc->action->flags & IRQF_SHARED))
41            desc->status |= IRQ_PENDING;
42        raw_spin_unlock(&desc->lock);
43        return ok;
44    }
45    /* Honour the normal IRQ locking */
46    desc->status |= IRQ_INPROGRESS;
47    action = desc->action;
48    raw_spin_unlock(&desc->lock);
49
50    while (action) {
51        /* Only shared IRQ handlers are safe to call */
52        if (action->flags & IRQF_SHARED) {
53            if (action->handler(irq, action->dev_id) ==
54                IRQ_HANDLED)
55                ok = 1;
56        }
57        action = action->next;
58    }
59    local_irq_disable();
60    /* Now clean up the flags */
61    raw_spin_lock(&desc->lock);
62    action = desc->action;
63
64    /*
65     * While we were looking for a fixup someone queued a real
66     * IRQ clashing with our walk:
67     */
68    while ((desc->status & IRQ_PENDING) && action) {
69        /*
70         * Perform real IRQ processing for the IRQ we deferred
71         */
72        work = 1;
73        raw_spin_unlock(&desc->lock);
74        handle_IRQ_event(irq, action);
75        raw_spin_lock(&desc->lock);
76        desc->status &= ~IRQ_PENDING;
77    }
78    desc->status &= ~IRQ_INPROGRESS;
79    /*
80     * If we did actual work for the real IRQ line we must let the
81     * IRQ controller clean up too
82     */
83    if (work)
84        irq_end(irq, desc);
85    raw_spin_unlock(&desc->lock);
86
87    return ok;
88}
89
90static int misrouted_irq(int irq)
91{
92    struct irq_desc *desc;
93    int i, ok = 0;
94
95    for_each_irq_desc(i, desc) {
96        if (!i)
97             continue;
98
99        if (i == irq) /* Already tried */
100            continue;
101
102        if (try_one_irq(i, desc))
103            ok = 1;
104    }
105    /* So the caller can adjust the irq error counts */
106    return ok;
107}
108
109static void poll_spurious_irqs(unsigned long dummy)
110{
111    struct irq_desc *desc;
112    int i;
113
114    for_each_irq_desc(i, desc) {
115        unsigned int status;
116
117        if (!i)
118             continue;
119
120        /* Racy but it doesn't matter */
121        status = desc->status;
122        barrier();
123        if (!(status & IRQ_SPURIOUS_DISABLED))
124            continue;
125
126        local_irq_disable();
127        try_one_irq(i, desc);
128        local_irq_enable();
129    }
130
131    mod_timer(&poll_spurious_irq_timer,
132          jiffies + POLL_SPURIOUS_IRQ_INTERVAL);
133}
134
135/*
136 * If 99,900 of the previous 100,000 interrupts have not been handled
137 * then assume that the IRQ is stuck in some manner. Drop a diagnostic
138 * and try to turn the IRQ off.
139 *
140 * (The other 100-of-100,000 interrupts may have been a correctly
141 * functioning device sharing an IRQ with the failing one)
142 *
143 * Called under desc->lock
144 */
145
146static void
147__report_bad_irq(unsigned int irq, struct irq_desc *desc,
148         irqreturn_t action_ret)
149{
150    struct irqaction *action;
151
152    if (action_ret != IRQ_HANDLED && action_ret != IRQ_NONE) {
153        printk(KERN_ERR "irq event %d: bogus return value %x\n",
154                irq, action_ret);
155    } else {
156        printk(KERN_ERR "irq %d: nobody cared (try booting with "
157                "the \"irqpoll\" option)\n", irq);
158    }
159    dump_stack();
160    printk(KERN_ERR "handlers:\n");
161
162    action = desc->action;
163    while (action) {
164        printk(KERN_ERR "[<%p>]", action->handler);
165        print_symbol(" (%s)",
166            (unsigned long)action->handler);
167        printk("\n");
168        action = action->next;
169    }
170}
171
172static void
173report_bad_irq(unsigned int irq, struct irq_desc *desc, irqreturn_t action_ret)
174{
175    static int count = 100;
176
177    if (count > 0) {
178        count--;
179        __report_bad_irq(irq, desc, action_ret);
180    }
181}
182
183static inline int
184try_misrouted_irq(unsigned int irq, struct irq_desc *desc,
185          irqreturn_t action_ret)
186{
187    struct irqaction *action;
188
189    if (!irqfixup)
190        return 0;
191
192    /* We didn't actually handle the IRQ - see if it was misrouted? */
193    if (action_ret == IRQ_NONE)
194        return 1;
195
196    /*
197     * But for 'irqfixup == 2' we also do it for handled interrupts if
198     * they are marked as IRQF_IRQPOLL (or for irq zero, which is the
199     * traditional PC timer interrupt.. Legacy)
200     */
201    if (irqfixup < 2)
202        return 0;
203
204    if (!irq)
205        return 1;
206
207    /*
208     * Since we don't get the descriptor lock, "action" can
209     * change under us. We don't really care, but we don't
210     * want to follow a NULL pointer. So tell the compiler to
211     * just load it once by using a barrier.
212     */
213    action = desc->action;
214    barrier();
215    return action && (action->flags & IRQF_IRQPOLL);
216}
217
218void note_interrupt(unsigned int irq, struct irq_desc *desc,
219            irqreturn_t action_ret)
220{
221    if (unlikely(action_ret != IRQ_HANDLED)) {
222        /*
223         * If we are seeing only the odd spurious IRQ caused by
224         * bus asynchronicity then don't eventually trigger an error,
225         * otherwise the counter becomes a doomsday timer for otherwise
226         * working systems
227         */
228        if (time_after(jiffies, desc->last_unhandled + HZ/10))
229            desc->irqs_unhandled = 1;
230        else
231            desc->irqs_unhandled++;
232        desc->last_unhandled = jiffies;
233        if (unlikely(action_ret != IRQ_NONE))
234            report_bad_irq(irq, desc, action_ret);
235    }
236
237    if (unlikely(try_misrouted_irq(irq, desc, action_ret))) {
238        int ok = misrouted_irq(irq);
239        if (action_ret == IRQ_NONE)
240            desc->irqs_unhandled -= ok;
241    }
242
243    desc->irq_count++;
244    if (likely(desc->irq_count < 100000))
245        return;
246
247    desc->irq_count = 0;
248    if (unlikely(desc->irqs_unhandled > 99900)) {
249        /*
250         * The interrupt is stuck
251         */
252        __report_bad_irq(irq, desc, action_ret);
253        /*
254         * Now kill the IRQ
255         */
256        printk(KERN_EMERG "Disabling IRQ #%d\n", irq);
257        desc->status |= IRQ_DISABLED | IRQ_SPURIOUS_DISABLED;
258        desc->depth++;
259        desc->irq_data.chip->irq_disable(&desc->irq_data);
260
261        mod_timer(&poll_spurious_irq_timer,
262              jiffies + POLL_SPURIOUS_IRQ_INTERVAL);
263    }
264    desc->irqs_unhandled = 0;
265}
266
267int noirqdebug __read_mostly;
268
269int noirqdebug_setup(char *str)
270{
271    noirqdebug = 1;
272    printk(KERN_INFO "IRQ lockup detection disabled\n");
273
274    return 1;
275}
276
277__setup("noirqdebug", noirqdebug_setup);
278module_param(noirqdebug, bool, 0644);
279MODULE_PARM_DESC(noirqdebug, "Disable irq lockup detection when true");
280
281static int __init irqfixup_setup(char *str)
282{
283    irqfixup = 1;
284    printk(KERN_WARNING "Misrouted IRQ fixup support enabled.\n");
285    printk(KERN_WARNING "This may impact system performance.\n");
286
287    return 1;
288}
289
290__setup("irqfixup", irqfixup_setup);
291module_param(irqfixup, int, 0644);
292
293static int __init irqpoll_setup(char *str)
294{
295    irqfixup = 2;
296    printk(KERN_WARNING "Misrouted IRQ fixup and polling support "
297                "enabled\n");
298    printk(KERN_WARNING "This may significantly impact system "
299                "performance\n");
300    return 1;
301}
302
303__setup("irqpoll", irqpoll_setup);
304

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