aboutsummaryrefslogtreecommitdiff
path: root/kernel/irq/spurious.c
blob: 02b2daf074414f1340a4f25cf134145150d90c1b (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
// SPDX-License-Identifier: GPL-2.0
/*
 * Copyright (C) 1992, 1998-2004 Linus Torvalds, Ingo Molnar
 *
 * This file contains spurious interrupt handling.
 */

#include <linux/jiffies.h>
#include <linux/irq.h>
#include <linux/module.h>
#include <linux/interrupt.h>
#include <linux/moduleparam.h>
#include <linux/timer.h>

#include "internals.h"

static int irqfixup __read_mostly;

#define POLL_SPURIOUS_IRQ_INTERVAL (HZ/10)
static void poll_spurious_irqs(struct timer_list *unused);
static DEFINE_TIMER(poll_spurious_irq_timer, poll_spurious_irqs);
static int irq_poll_cpu;
static atomic_t irq_poll_active;

/*
 * We wait here for a poller to finish.
 *
 * If the poll runs on this CPU, then we yell loudly and return
 * false. That will leave the interrupt line disabled in the worst
 * case, but it should never happen.
 *
 * We wait until the poller is done and then recheck disabled and
 * action (about to be disabled). Only if it's still active, we return
 * true and let the handler run.
 */
bool irq_wait_for_poll(struct irq_desc *desc)
	__must_hold(&desc->lock)
{
	if (WARN_ONCE(irq_poll_cpu == smp_processor_id(),
		      "irq poll in progress on cpu %d for irq %d\n",
		      smp_processor_id(), desc->irq_data.irq))
		return false;

#ifdef CONFIG_SMP
	do {
		raw_spin_unlock(&desc->lock);
		while (irqd_irq_inprogress(&desc->irq_data))
			cpu_relax();
		raw_spin_lock(&desc->lock);
	} while (irqd_irq_inprogress(&desc->irq_data));
	/* Might have been disabled in meantime */
	return !irqd_irq_disabled(&desc->irq_data) && desc->action;
#else
	return false;
#endif
}


/*
 * Recovery handler for misrouted interrupts.
 */
static int try_one_irq(struct irq_desc *desc, bool force)
{
	irqreturn_t ret = IRQ_NONE;
	struct irqaction *action;

	raw_spin_lock(&desc->lock);

	/*
	 * PER_CPU, nested thread interrupts and interrupts explicitly
	 * marked polled are excluded from polling.
	 */
	if (irq_settings_is_per_cpu(desc) ||
	    irq_settings_is_nested_thread(desc) ||
	    irq_settings_is_polled(desc))
		goto out;

	/*
	 * Do not poll disabled interrupts unless the spurious
	 * disabled poller asks explicitly.
	 */
	if (irqd_irq_disabled(&desc->irq_data) && !force)
		goto out;

	/*
	 * All handlers must agree on IRQF_SHARED, so we test just the
	 * first.
	 */
	action = desc->action;
	if (!action || !(action->flags & IRQF_SHARED) ||
	    (action->flags & __IRQF_TIMER))
		goto out;

	/* Already running on another processor */
	if (irqd_irq_inprogress(&desc->irq_data)) {
		/*
		 * Already running: If it is shared get the other
		 * CPU to go looking for our mystery interrupt too
		 */
		desc->istate |= IRQS_PENDING;
		goto out;
	}

	/* Mark it poll in progress */
	desc->istate |= IRQS_POLL_INPROGRESS;
	do {
		if (handle_irq_event(desc) == IRQ_HANDLED)
			ret = IRQ_HANDLED;
		/* Make sure that there is still a valid action */
		action = desc->action;
	} while ((desc->istate & IRQS_PENDING) && action);
	desc->istate &= ~IRQS_POLL_INPROGRESS;
out:
	raw_spin_unlock(&desc->lock);
	return ret == IRQ_HANDLED;
}

static int misrouted_irq(int irq)
{
	struct irq_desc *desc;
	int i, ok = 0;

	if (atomic_inc_return(&irq_poll_active) != 1)
		goto out;

	irq_poll_cpu = smp_processor_id();

	for_each_irq_desc(i, desc) {
		if (!i)
			 continue;

		if (i == irq)	/* Already tried */
			continue;

		if (try_one_irq(desc, false))
			ok = 1;
	}
out:
	atomic_dec(&irq_poll_active);
	/* So the caller can adjust the irq error counts */
	return ok;
}

static void poll_spurious_irqs(struct timer_list *unused)
{
	struct irq_desc *desc;
	int i;

	if (atomic_inc_return(&irq_poll_active) != 1)
		goto out;
	irq_poll_cpu = smp_processor_id();

	for_each_irq_desc(i, desc) {
		unsigned int state;

		if (!i)
			 continue;

		/* Racy but it doesn't matter */
		state = desc->istate;
		barrier();
		if (!(state & IRQS_SPURIOUS_DISABLED))
			continue;

		local_irq_disable();
		try_one_irq(desc, true);
		local_irq_enable();
	}
out:
	atomic_dec(&irq_poll_active);
	mod_timer(&poll_spurious_irq_timer,
		  jiffies + POLL_SPURIOUS_IRQ_INTERVAL);
}

static inline int bad_action_ret(irqreturn_t action_ret)
{
	unsigned int r = action_ret;

	if (likely(r <= (IRQ_HANDLED | IRQ_WAKE_THREAD)))
		return 0;
	return 1;
}

/*
 * If 99,900 of the previous 100,000 interrupts have not been handled
 * then assume that the IRQ is stuck in some manner. Drop a diagnostic
 * and try to turn the IRQ off.
 *
 * (The other 100-of-100,000 interrupts may have been a correctly
 *  functioning device sharing an IRQ with the failing one)
 */
static void __report_bad_irq(struct irq_desc *desc, irqreturn_t action_ret)
{
	unsigned int irq = irq_desc_get_irq(desc);
	struct irqaction *action;
	unsigned long flags;

	if (bad_action_ret(action_ret)) {
		printk(KERN_ERR "irq event %d: bogus return value %x\n",
				irq, action_ret);
	} else {
		printk(KERN_ERR "irq %d: nobody cared (try booting with "
				"the \"irqpoll\" option)\n", irq);
	}
	dump_stack();
	printk(KERN_ERR "handlers:\n");

	/*
	 * We need to take desc->lock here. note_interrupt() is called
	 * w/o desc->lock held, but IRQ_PROGRESS set. We might race
	 * with something else removing an action. It's ok to take
	 * desc->lock here. See synchronize_irq().
	 */
	raw_spin_lock_irqsave(&desc->lock, flags);
	for_each_action_of_desc(desc, action) {
		printk(KERN_ERR "[<%p>] %ps", action->handler, action->handler);
		if (action->thread_fn)
			printk(KERN_CONT " threaded [<%p>] %ps",
					action->thread_fn, action->thread_fn);
		printk(KERN_CONT "\n");
	}
	raw_spin_unlock_irqrestore(&desc->lock, flags);
}

static void report_bad_irq(struct irq_desc *desc, irqreturn_t action_ret)
{
	static int count = 100;

	if (count > 0) {
		count--;
		__report_bad_irq(desc, action_ret);
	}
}

static inline int
try_misrouted_irq(unsigned int irq, struct irq_desc *desc,
		  irqreturn_t action_ret)
{
	struct irqaction *action;

	if (!irqfixup)
		return 0;

	/* We didn't actually handle the IRQ - see if it was misrouted? */
	if (action_ret == IRQ_NONE)
		return 1;

	/*
	 * But for 'irqfixup == 2' we also do it for handled interrupts if
	 * they are marked as IRQF_IRQPOLL (or for irq zero, which is the
	 * traditional PC timer interrupt.. Legacy)
	 */
	if (irqfixup < 2)
		return 0;

	if (!irq)
		return 1;

	/*
	 * Since we don't get the descriptor lock, "action" can
	 * change under us.  We don't really care, but we don't
	 * want to follow a NULL pointer. So tell the compiler to
	 * just load it once by using a barrier.
	 */
	action = desc->action;
	barrier();
	return action && (action->flags & IRQF_IRQPOLL);
}

#define SPURIOUS_DEFERRED	0x80000000

void note_interrupt(struct irq_desc *desc, irqreturn_t action_ret)
{
	unsigned int irq;

	if (desc->istate & IRQS_POLL_INPROGRESS ||
	    irq_settings_is_polled(desc))
		return;

	if (bad_action_ret(action_ret)) {
		report_bad_irq(desc, action_ret);
		return;
	}

	/*
	 * We cannot call note_interrupt from the threaded handler
	 * because we need to look at the compound of all handlers
	 * (primary and threaded). Aside of that in the threaded
	 * shared case we have no serialization against an incoming
	 * hardware interrupt while we are dealing with a threaded
	 * result.
	 *
	 * So in case a thread is woken, we just note the fact and
	 * defer the analysis to the next hardware interrupt.
	 *
	 * The threaded handlers store whether they successfully
	 * handled an interrupt and we check whether that number
	 * changed versus the last invocation.
	 *
	 * We could handle all interrupts with the delayed by one
	 * mechanism, but for the non forced threaded case we'd just
	 * add pointless overhead to the straight hardirq interrupts
	 * for the sake of a few lines less code.
	 */
	if (action_ret & IRQ_WAKE_THREAD) {
		/*
		 * There is a thread woken. Check whether one of the
		 * shared primary handlers returned IRQ_HANDLED. If
		 * not we defer the spurious detection to the next
		 * interrupt.
		 */
		if (action_ret == IRQ_WAKE_THREAD) {
			int handled;
			/*
			 * We use bit 31 of thread_handled_last to
			 * denote the deferred spurious detection
			 * active. No locking necessary as
			 * thread_handled_last is only accessed here
			 * and we have the guarantee that hard
			 * interrupts are not reentrant.
			 */
			if (!(desc->threads_handled_last & SPURIOUS_DEFERRED)) {
				desc->threads_handled_last |= SPURIOUS_DEFERRED;
				return;
			}
			/*
			 * Check whether one of the threaded handlers
			 * returned IRQ_HANDLED since the last
			 * interrupt happened.
			 *
			 * For simplicity we just set bit 31, as it is
			 * set in threads_handled_last as well. So we
			 * avoid extra masking. And we really do not
			 * care about the high bits of the handled
			 * count. We just care about the count being
			 * different than the one we saw before.
			 */
			handled = atomic_read(&desc->threads_handled);
			handled |= SPURIOUS_DEFERRED;
			if (handled != desc->threads_handled_last) {
				action_ret = IRQ_HANDLED;
				/*
				 * Note: We keep the SPURIOUS_DEFERRED
				 * bit set. We are handling the
				 * previous invocation right now.
				 * Keep it for the current one, so the
				 * next hardware interrupt will
				 * account for it.
				 */
				desc->threads_handled_last = handled;
			} else {
				/*
				 * None of the threaded handlers felt
				 * responsible for the last interrupt
				 *
				 * We keep the SPURIOUS_DEFERRED bit
				 * set in threads_handled_last as we
				 * need to account for the current
				 * interrupt as well.
				 */
				action_ret = IRQ_NONE;
			}
		} else {
			/*
			 * One of the primary handlers returned
			 * IRQ_HANDLED. So we don't care about the
			 * threaded handlers on the same line. Clear
			 * the deferred detection bit.
			 *
			 * In theory we could/should check whether the
			 * deferred bit is set and take the result of
			 * the previous run into account here as
			 * well. But it's really not worth the
			 * trouble. If every other interrupt is
			 * handled we never trigger the spurious
			 * detector. And if this is just the one out
			 * of 100k unhandled ones which is handled
			 * then we merily delay the spurious detection
			 * by one hard interrupt. Not a real problem.
			 */
			desc->threads_handled_last &= ~SPURIOUS_DEFERRED;
		}
	}

	if (unlikely(action_ret == IRQ_NONE)) {
		/*
		 * If we are seeing only the odd spurious IRQ caused by
		 * bus asynchronicity then don't eventually trigger an error,
		 * otherwise the counter becomes a doomsday timer for otherwise
		 * working systems
		 */
		if (time_after(jiffies, desc->last_unhandled + HZ/10))
			desc->irqs_unhandled = 1;
		else
			desc->irqs_unhandled++;
		desc->last_unhandled = jiffies;
	}

	irq = irq_desc_get_irq(desc);
	if (unlikely(try_misrouted_irq(irq, desc, action_ret))) {
		int ok = misrouted_irq(irq);
		if (action_ret == IRQ_NONE)
			desc->irqs_unhandled -= ok;
	}

	if (likely(!desc->irqs_unhandled))
		return;

	/* Now getting into unhandled irq detection */
	desc->irq_count++;
	if (likely(desc->irq_count < 100000))
		return;

	desc->irq_count = 0;
	if (unlikely(desc->irqs_unhandled > 99900)) {
		/*
		 * The interrupt is stuck
		 */
		__report_bad_irq(desc, action_ret);
		/*
		 * Now kill the IRQ
		 */
		printk(KERN_EMERG "Disabling IRQ #%d\n", irq);
		desc->istate |= IRQS_SPURIOUS_DISABLED;
		desc->depth++;
		irq_disable(desc);

		mod_timer(&poll_spurious_irq_timer,
			  jiffies + POLL_SPURIOUS_IRQ_INTERVAL);
	}
	desc->irqs_unhandled = 0;
}

bool noirqdebug __read_mostly;

int noirqdebug_setup(char *str)
{
	noirqdebug = 1;
	printk(KERN_INFO "IRQ lockup detection disabled\n");

	return 1;
}

__setup("noirqdebug", noirqdebug_setup);
module_param(noirqdebug, bool, 0644);
MODULE_PARM_DESC(noirqdebug, "Disable irq lockup detection when true");

static int __init irqfixup_setup(char *str)
{
	if (IS_ENABLED(CONFIG_PREEMPT_RT)) {
		pr_warn("irqfixup boot option not supported with PREEMPT_RT\n");
		return 1;
	}
	irqfixup = 1;
	printk(KERN_WARNING "Misrouted IRQ fixup support enabled.\n");
	printk(KERN_WARNING "This may impact system performance.\n");

	return 1;
}

__setup("irqfixup", irqfixup_setup);
module_param(irqfixup, int, 0644);

static int __init irqpoll_setup(char *str)
{
	if (IS_ENABLED(CONFIG_PREEMPT_RT)) {
		pr_warn("irqpoll boot option not supported with PREEMPT_RT\n");
		return 1;
	}
	irqfixup = 2;
	printk(KERN_WARNING "Misrouted IRQ fixup and polling support "
				"enabled\n");
	printk(KERN_WARNING "This may significantly impact system "
				"performance\n");
	return 1;
}

__setup("irqpoll", irqpoll_setup);