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Linux/kernel/irq/spurious.c

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

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