1 // SPDX-License-Identifier: GPL-2.0
2 /*
3 * Copyright (C) 1992, 1998-2004 Linus Torvalds, Ingo Molnar
4 *
5 * This file contains spurious interrupt handling.
6 */
7
8 #include <linux/jiffies.h>
9 #include <linux/irq.h>
10 #include <linux/module.h>
11 #include <linux/interrupt.h>
12 #include <linux/moduleparam.h>
13 #include <linux/timer.h>
14
15 #include "internals.h"
16
17 static int irqfixup __read_mostly;
18
19 #define POLL_SPURIOUS_IRQ_INTERVAL (HZ/10)
20 static void poll_spurious_irqs(struct timer_list *unused);
21 static DEFINE_TIMER(poll_spurious_irq_timer, poll_spurious_irqs);
22 static int irq_poll_cpu;
23 static atomic_t irq_poll_active;
24
25 /*
26 * We wait here for a poller to finish.
27 *
28 * If the poll runs on this CPU, then we yell loudly and return
29 * false. That will leave the interrupt line disabled in the worst
30 * case, but it should never happen.
31 *
32 * We wait until the poller is done and then recheck disabled and
33 * action (about to be disabled). Only if it's still active, we return
34 * true and let the handler run.
35 */
irq_wait_for_poll(struct irq_desc * desc)36 bool irq_wait_for_poll(struct irq_desc *desc)
37 __must_hold(&desc->lock)
38 {
39 if (WARN_ONCE(irq_poll_cpu == smp_processor_id(),
40 "irq poll in progress on cpu %d for irq %d\n",
41 smp_processor_id(), desc->irq_data.irq))
42 return false;
43
44 #ifdef CONFIG_SMP
45 do {
46 raw_spin_unlock(&desc->lock);
47 while (irqd_irq_inprogress(&desc->irq_data))
48 cpu_relax();
49 raw_spin_lock(&desc->lock);
50 } while (irqd_irq_inprogress(&desc->irq_data));
51 /* Might have been disabled in meantime */
52 return !irqd_irq_disabled(&desc->irq_data) && desc->action;
53 #else
54 return false;
55 #endif
56 }
57
58
59 /*
60 * Recovery handler for misrouted interrupts.
61 */
try_one_irq(struct irq_desc * desc,bool force)62 static int try_one_irq(struct irq_desc *desc, bool force)
63 {
64 irqreturn_t ret = IRQ_NONE;
65 struct irqaction *action;
66
67 raw_spin_lock(&desc->lock);
68
69 /*
70 * PER_CPU, nested thread interrupts and interrupts explicitly
71 * marked polled are excluded from polling.
72 */
73 if (irq_settings_is_per_cpu(desc) ||
74 irq_settings_is_nested_thread(desc) ||
75 irq_settings_is_polled(desc))
76 goto out;
77
78 /*
79 * Do not poll disabled interrupts unless the spurious
80 * disabled poller asks explicitly.
81 */
82 if (irqd_irq_disabled(&desc->irq_data) && !force)
83 goto out;
84
85 /*
86 * All handlers must agree on IRQF_SHARED, so we test just the
87 * first.
88 */
89 action = desc->action;
90 if (!action || !(action->flags & IRQF_SHARED) ||
91 (action->flags & __IRQF_TIMER))
92 goto out;
93
94 /* Already running on another processor */
95 if (irqd_irq_inprogress(&desc->irq_data)) {
96 /*
97 * Already running: If it is shared get the other
98 * CPU to go looking for our mystery interrupt too
99 */
100 desc->istate |= IRQS_PENDING;
101 goto out;
102 }
103
104 /* Mark it poll in progress */
105 desc->istate |= IRQS_POLL_INPROGRESS;
106 do {
107 if (handle_irq_event(desc) == IRQ_HANDLED)
108 ret = IRQ_HANDLED;
109 /* Make sure that there is still a valid action */
110 action = desc->action;
111 } while ((desc->istate & IRQS_PENDING) && action);
112 desc->istate &= ~IRQS_POLL_INPROGRESS;
113 out:
114 raw_spin_unlock(&desc->lock);
115 return ret == IRQ_HANDLED;
116 }
117
misrouted_irq(int irq)118 static int misrouted_irq(int irq)
119 {
120 struct irq_desc *desc;
121 int i, ok = 0;
122
123 if (atomic_inc_return(&irq_poll_active) != 1)
124 goto out;
125
126 irq_poll_cpu = smp_processor_id();
127
128 for_each_irq_desc(i, desc) {
129 if (!i)
130 continue;
131
132 if (i == irq) /* Already tried */
133 continue;
134
135 if (try_one_irq(desc, false))
136 ok = 1;
137 }
138 out:
139 atomic_dec(&irq_poll_active);
140 /* So the caller can adjust the irq error counts */
141 return ok;
142 }
143
poll_spurious_irqs(struct timer_list * unused)144 static void poll_spurious_irqs(struct timer_list *unused)
145 {
146 struct irq_desc *desc;
147 int i;
148
149 if (atomic_inc_return(&irq_poll_active) != 1)
150 goto out;
151 irq_poll_cpu = smp_processor_id();
152
153 for_each_irq_desc(i, desc) {
154 unsigned int state;
155
156 if (!i)
157 continue;
158
159 /* Racy but it doesn't matter */
160 state = desc->istate;
161 barrier();
162 if (!(state & IRQS_SPURIOUS_DISABLED))
163 continue;
164
165 local_irq_disable();
166 try_one_irq(desc, true);
167 local_irq_enable();
168 }
169 out:
170 atomic_dec(&irq_poll_active);
171 mod_timer(&poll_spurious_irq_timer,
172 jiffies + POLL_SPURIOUS_IRQ_INTERVAL);
173 }
174
bad_action_ret(irqreturn_t action_ret)175 static inline int bad_action_ret(irqreturn_t action_ret)
176 {
177 unsigned int r = action_ret;
178
179 if (likely(r <= (IRQ_HANDLED | IRQ_WAKE_THREAD)))
180 return 0;
181 return 1;
182 }
183
184 /*
185 * If 99,900 of the previous 100,000 interrupts have not been handled
186 * then assume that the IRQ is stuck in some manner. Drop a diagnostic
187 * and try to turn the IRQ off.
188 *
189 * (The other 100-of-100,000 interrupts may have been a correctly
190 * functioning device sharing an IRQ with the failing one)
191 */
__report_bad_irq(struct irq_desc * desc,irqreturn_t action_ret)192 static void __report_bad_irq(struct irq_desc *desc, irqreturn_t action_ret)
193 {
194 unsigned int irq = irq_desc_get_irq(desc);
195 struct irqaction *action;
196 unsigned long flags;
197
198 if (bad_action_ret(action_ret)) {
199 printk(KERN_ERR "irq event %d: bogus return value %x\n",
200 irq, action_ret);
201 } else {
202 printk(KERN_ERR "irq %d: nobody cared (try booting with "
203 "the \"irqpoll\" option)\n", irq);
204 }
205 dump_stack();
206 printk(KERN_ERR "handlers:\n");
207
208 /*
209 * We need to take desc->lock here. note_interrupt() is called
210 * w/o desc->lock held, but IRQ_PROGRESS set. We might race
211 * with something else removing an action. It's ok to take
212 * desc->lock here. See synchronize_irq().
213 */
214 raw_spin_lock_irqsave(&desc->lock, flags);
215 for_each_action_of_desc(desc, action) {
216 printk(KERN_ERR "[<%p>] %ps", action->handler, action->handler);
217 if (action->thread_fn)
218 printk(KERN_CONT " threaded [<%p>] %ps",
219 action->thread_fn, action->thread_fn);
220 printk(KERN_CONT "\n");
221 }
222 raw_spin_unlock_irqrestore(&desc->lock, flags);
223 }
224
report_bad_irq(struct irq_desc * desc,irqreturn_t action_ret)225 static void report_bad_irq(struct irq_desc *desc, irqreturn_t action_ret)
226 {
227 static int count = 100;
228
229 if (count > 0) {
230 count--;
231 __report_bad_irq(desc, action_ret);
232 }
233 }
234
235 static inline int
try_misrouted_irq(unsigned int irq,struct irq_desc * desc,irqreturn_t action_ret)236 try_misrouted_irq(unsigned int irq, struct irq_desc *desc,
237 irqreturn_t action_ret)
238 {
239 struct irqaction *action;
240
241 if (!irqfixup)
242 return 0;
243
244 /* We didn't actually handle the IRQ - see if it was misrouted? */
245 if (action_ret == IRQ_NONE)
246 return 1;
247
248 /*
249 * But for 'irqfixup == 2' we also do it for handled interrupts if
250 * they are marked as IRQF_IRQPOLL (or for irq zero, which is the
251 * traditional PC timer interrupt.. Legacy)
252 */
253 if (irqfixup < 2)
254 return 0;
255
256 if (!irq)
257 return 1;
258
259 /*
260 * Since we don't get the descriptor lock, "action" can
261 * change under us. We don't really care, but we don't
262 * want to follow a NULL pointer. So tell the compiler to
263 * just load it once by using a barrier.
264 */
265 action = desc->action;
266 barrier();
267 return action && (action->flags & IRQF_IRQPOLL);
268 }
269
270 #define SPURIOUS_DEFERRED 0x80000000
271
note_interrupt(struct irq_desc * desc,irqreturn_t action_ret)272 void note_interrupt(struct irq_desc *desc, irqreturn_t action_ret)
273 {
274 unsigned int irq;
275
276 if (desc->istate & IRQS_POLL_INPROGRESS ||
277 irq_settings_is_polled(desc))
278 return;
279
280 if (bad_action_ret(action_ret)) {
281 report_bad_irq(desc, action_ret);
282 return;
283 }
284
285 /*
286 * We cannot call note_interrupt from the threaded handler
287 * because we need to look at the compound of all handlers
288 * (primary and threaded). Aside of that in the threaded
289 * shared case we have no serialization against an incoming
290 * hardware interrupt while we are dealing with a threaded
291 * result.
292 *
293 * So in case a thread is woken, we just note the fact and
294 * defer the analysis to the next hardware interrupt.
295 *
296 * The threaded handlers store whether they successfully
297 * handled an interrupt and we check whether that number
298 * changed versus the last invocation.
299 *
300 * We could handle all interrupts with the delayed by one
301 * mechanism, but for the non forced threaded case we'd just
302 * add pointless overhead to the straight hardirq interrupts
303 * for the sake of a few lines less code.
304 */
305 if (action_ret & IRQ_WAKE_THREAD) {
306 /*
307 * There is a thread woken. Check whether one of the
308 * shared primary handlers returned IRQ_HANDLED. If
309 * not we defer the spurious detection to the next
310 * interrupt.
311 */
312 if (action_ret == IRQ_WAKE_THREAD) {
313 int handled;
314 /*
315 * We use bit 31 of thread_handled_last to
316 * denote the deferred spurious detection
317 * active. No locking necessary as
318 * thread_handled_last is only accessed here
319 * and we have the guarantee that hard
320 * interrupts are not reentrant.
321 */
322 if (!(desc->threads_handled_last & SPURIOUS_DEFERRED)) {
323 desc->threads_handled_last |= SPURIOUS_DEFERRED;
324 return;
325 }
326 /*
327 * Check whether one of the threaded handlers
328 * returned IRQ_HANDLED since the last
329 * interrupt happened.
330 *
331 * For simplicity we just set bit 31, as it is
332 * set in threads_handled_last as well. So we
333 * avoid extra masking. And we really do not
334 * care about the high bits of the handled
335 * count. We just care about the count being
336 * different than the one we saw before.
337 */
338 handled = atomic_read(&desc->threads_handled);
339 handled |= SPURIOUS_DEFERRED;
340 if (handled != desc->threads_handled_last) {
341 action_ret = IRQ_HANDLED;
342 /*
343 * Note: We keep the SPURIOUS_DEFERRED
344 * bit set. We are handling the
345 * previous invocation right now.
346 * Keep it for the current one, so the
347 * next hardware interrupt will
348 * account for it.
349 */
350 desc->threads_handled_last = handled;
351 } else {
352 /*
353 * None of the threaded handlers felt
354 * responsible for the last interrupt
355 *
356 * We keep the SPURIOUS_DEFERRED bit
357 * set in threads_handled_last as we
358 * need to account for the current
359 * interrupt as well.
360 */
361 action_ret = IRQ_NONE;
362 }
363 } else {
364 /*
365 * One of the primary handlers returned
366 * IRQ_HANDLED. So we don't care about the
367 * threaded handlers on the same line. Clear
368 * the deferred detection bit.
369 *
370 * In theory we could/should check whether the
371 * deferred bit is set and take the result of
372 * the previous run into account here as
373 * well. But it's really not worth the
374 * trouble. If every other interrupt is
375 * handled we never trigger the spurious
376 * detector. And if this is just the one out
377 * of 100k unhandled ones which is handled
378 * then we merily delay the spurious detection
379 * by one hard interrupt. Not a real problem.
380 */
381 desc->threads_handled_last &= ~SPURIOUS_DEFERRED;
382 }
383 }
384
385 if (unlikely(action_ret == IRQ_NONE)) {
386 /*
387 * If we are seeing only the odd spurious IRQ caused by
388 * bus asynchronicity then don't eventually trigger an error,
389 * otherwise the counter becomes a doomsday timer for otherwise
390 * working systems
391 */
392 if (time_after(jiffies, desc->last_unhandled + HZ/10))
393 desc->irqs_unhandled = 1;
394 else
395 desc->irqs_unhandled++;
396 desc->last_unhandled = jiffies;
397 }
398
399 irq = irq_desc_get_irq(desc);
400 if (unlikely(try_misrouted_irq(irq, desc, action_ret))) {
401 int ok = misrouted_irq(irq);
402 if (action_ret == IRQ_NONE)
403 desc->irqs_unhandled -= ok;
404 }
405
406 if (likely(!desc->irqs_unhandled))
407 return;
408
409 /* Now getting into unhandled irq detection */
410 desc->irq_count++;
411 if (likely(desc->irq_count < 100000))
412 return;
413
414 desc->irq_count = 0;
415 if (unlikely(desc->irqs_unhandled > 99900)) {
416 /*
417 * The interrupt is stuck
418 */
419 __report_bad_irq(desc, action_ret);
420 /*
421 * Now kill the IRQ
422 */
423 printk(KERN_EMERG "Disabling IRQ #%d\n", irq);
424 desc->istate |= IRQS_SPURIOUS_DISABLED;
425 desc->depth++;
426 irq_disable(desc);
427
428 mod_timer(&poll_spurious_irq_timer,
429 jiffies + POLL_SPURIOUS_IRQ_INTERVAL);
430 }
431 desc->irqs_unhandled = 0;
432 }
433
434 bool noirqdebug __read_mostly;
435
noirqdebug_setup(char * str)436 int noirqdebug_setup(char *str)
437 {
438 noirqdebug = 1;
439 printk(KERN_INFO "IRQ lockup detection disabled\n");
440
441 return 1;
442 }
443
444 __setup("noirqdebug", noirqdebug_setup);
445 module_param(noirqdebug, bool, 0644);
446 MODULE_PARM_DESC(noirqdebug, "Disable irq lockup detection when true");
447
irqfixup_setup(char * str)448 static int __init irqfixup_setup(char *str)
449 {
450 if (IS_ENABLED(CONFIG_PREEMPT_RT)) {
451 pr_warn("irqfixup boot option not supported with PREEMPT_RT\n");
452 return 1;
453 }
454 irqfixup = 1;
455 printk(KERN_WARNING "Misrouted IRQ fixup support enabled.\n");
456 printk(KERN_WARNING "This may impact system performance.\n");
457
458 return 1;
459 }
460
461 __setup("irqfixup", irqfixup_setup);
462 module_param(irqfixup, int, 0644);
463
irqpoll_setup(char * str)464 static int __init irqpoll_setup(char *str)
465 {
466 if (IS_ENABLED(CONFIG_PREEMPT_RT)) {
467 pr_warn("irqpoll boot option not supported with PREEMPT_RT\n");
468 return 1;
469 }
470 irqfixup = 2;
471 printk(KERN_WARNING "Misrouted IRQ fixup and polling support "
472 "enabled\n");
473 printk(KERN_WARNING "This may significantly impact system "
474 "performance\n");
475 return 1;
476 }
477
478 __setup("irqpoll", irqpoll_setup);
479