kernel/irq/spurious.c

0001 // SPDX-License-Identifier: GPL-2.0
0002 /*
0003  * Copyright (C) 1992, 1998-2004 Linus Torvalds, Ingo Molnar
0004  *
0005  * This file contains spurious interrupt handling.
0006  */
0007
0008 #include <linux/jiffies.h>
0009 #include <linux/irq.h>
0010 #include <linux/module.h>
0011 #include <linux/interrupt.h>
0012 #include <linux/moduleparam.h>
0013 #include <linux/timer.h>
0014
0015 #include "internals.h"
0016
0017 static int irqfixup __read_mostly;
0018
0019 #define POLL_SPURIOUS_IRQ_INTERVAL (HZ/10)
0020 static void poll_spurious_irqs(struct timer_list *unused);
0021 static DEFINE_TIMER(poll_spurious_irq_timer, poll_spurious_irqs);
0022 static int irq_poll_cpu;
0023 static atomic_t irq_poll_active;
0024
0025 /*
0026  * We wait here for a poller to finish.
0027  *
0028  * If the poll runs on this CPU, then we yell loudly and return
0029  * false. That will leave the interrupt line disabled in the worst
0030  * case, but it should never happen.
0031  *
0032  * We wait until the poller is done and then recheck disabled and
0033  * action (about to be disabled). Only if it's still active, we return
0034  * true and let the handler run.
0035  */
0036 bool irq_wait_for_poll(struct irq_desc *desc)
0037     __must_hold(&desc->lock)
0038 {
0039     if (WARN_ONCE(irq_poll_cpu == smp_processor_id(),
0040               "irq poll in progress on cpu %d for irq %d\n",
0041               smp_processor_id(), desc->irq_data.irq))
0042         return false;
0043
0044 #ifdef CONFIG_SMP
0045     do {
0046         raw_spin_unlock(&desc->lock);
0047         while (irqd_irq_inprogress(&desc->irq_data))
0048             cpu_relax();
0049         raw_spin_lock(&desc->lock);
0050     } while (irqd_irq_inprogress(&desc->irq_data));
0051     /* Might have been disabled in meantime */
0052     return !irqd_irq_disabled(&desc->irq_data) && desc->action;
0053 #else
0054     return false;
0055 #endif
0056 }
0057
0058
0059 /*
0060  * Recovery handler for misrouted interrupts.
0061  */
0062 static int try_one_irq(struct irq_desc *desc, bool force)
0063 {
0064     irqreturn_t ret = IRQ_NONE;
0065     struct irqaction *action;
0066
0067     raw_spin_lock(&desc->lock);
0068
0069     /*
0070      * PER_CPU, nested thread interrupts and interrupts explicitly
0071      * marked polled are excluded from polling.
0072      */
0073     if (irq_settings_is_per_cpu(desc) ||
0074         irq_settings_is_nested_thread(desc) ||
0075         irq_settings_is_polled(desc))
0076         goto out;
0077
0078     /*
0079      * Do not poll disabled interrupts unless the spurious
0080      * disabled poller asks explicitly.
0081      */
0082     if (irqd_irq_disabled(&desc->irq_data) && !force)
0083         goto out;
0084
0085     /*
0086      * All handlers must agree on IRQF_SHARED, so we test just the
0087      * first.
0088      */
0089     action = desc->action;
0090     if (!action || !(action->flags & IRQF_SHARED) ||
0091         (action->flags & __IRQF_TIMER))
0092         goto out;
0093
0094     /* Already running on another processor */
0095     if (irqd_irq_inprogress(&desc->irq_data)) {
0096         /*
0097          * Already running: If it is shared get the other
0098          * CPU to go looking for our mystery interrupt too
0099          */
0100         desc->istate |= IRQS_PENDING;
0101         goto out;
0102     }
0103
0104     /* Mark it poll in progress */
0105     desc->istate |= IRQS_POLL_INPROGRESS;
0106     do {
0107         if (handle_irq_event(desc) == IRQ_HANDLED)
0108             ret = IRQ_HANDLED;
0109         /* Make sure that there is still a valid action */
0110         action = desc->action;
0111     } while ((desc->istate & IRQS_PENDING) && action);
0112     desc->istate &= ~IRQS_POLL_INPROGRESS;
0113 out:
0114     raw_spin_unlock(&desc->lock);
0115     return ret == IRQ_HANDLED;
0116 }
0117
0118 static int misrouted_irq(int irq)
0119 {
0120     struct irq_desc *desc;
0121     int i, ok = 0;
0122
0123     if (atomic_inc_return(&irq_poll_active) != 1)
0124         goto out;
0125
0126     irq_poll_cpu = smp_processor_id();
0127
0128     for_each_irq_desc(i, desc) {
0129         if (!i)
0130              continue;
0131
0132         if (i == irq)   /* Already tried */
0133             continue;
0134
0135         if (try_one_irq(desc, false))
0136             ok = 1;
0137     }
0138 out:
0139     atomic_dec(&irq_poll_active);
0140     /* So the caller can adjust the irq error counts */
0141     return ok;
0142 }
0143
0144 static void poll_spurious_irqs(struct timer_list *unused)
0145 {
0146     struct irq_desc *desc;
0147     int i;
0148
0149     if (atomic_inc_return(&irq_poll_active) != 1)
0150         goto out;
0151     irq_poll_cpu = smp_processor_id();
0152
0153     for_each_irq_desc(i, desc) {
0154         unsigned int state;
0155
0156         if (!i)
0157              continue;
0158
0159         /* Racy but it doesn't matter */
0160         state = desc->istate;
0161         barrier();
0162         if (!(state & IRQS_SPURIOUS_DISABLED))
0163             continue;
0164
0165         local_irq_disable();
0166         try_one_irq(desc, true);
0167         local_irq_enable();
0168     }
0169 out:
0170     atomic_dec(&irq_poll_active);
0171     mod_timer(&poll_spurious_irq_timer,
0172           jiffies + POLL_SPURIOUS_IRQ_INTERVAL);
0173 }
0174
0175 static inline int bad_action_ret(irqreturn_t action_ret)
0176 {
0177     unsigned int r = action_ret;
0178
0179     if (likely(r <= (IRQ_HANDLED | IRQ_WAKE_THREAD)))
0180         return 0;
0181     return 1;
0182 }
0183
0184 /*
0185  * If 99,900 of the previous 100,000 interrupts have not been handled
0186  * then assume that the IRQ is stuck in some manner. Drop a diagnostic
0187  * and try to turn the IRQ off.
0188  *
0189  * (The other 100-of-100,000 interrupts may have been a correctly
0190  *  functioning device sharing an IRQ with the failing one)
0191  */
0192 static void __report_bad_irq(struct irq_desc *desc, irqreturn_t action_ret)
0193 {
0194     unsigned int irq = irq_desc_get_irq(desc);
0195     struct irqaction *action;
0196     unsigned long flags;
0197
0198     if (bad_action_ret(action_ret)) {
0199         printk(KERN_ERR "irq event %d: bogus return value %x\n",
0200                 irq, action_ret);
0201     } else {
0202         printk(KERN_ERR "irq %d: nobody cared (try booting with "
0203                 "the \"irqpoll\" option)\n", irq);
0204     }
0205     dump_stack();
0206     printk(KERN_ERR "handlers:\n");
0207
0208     /*
0209      * We need to take desc->lock here. note_interrupt() is called
0210      * w/o desc->lock held, but IRQ_PROGRESS set. We might race
0211      * with something else removing an action. It's ok to take
0212      * desc->lock here. See synchronize_irq().
0213      */
0214     raw_spin_lock_irqsave(&desc->lock, flags);
0215     for_each_action_of_desc(desc, action) {
0216         printk(KERN_ERR "[<%p>] %ps", action->handler, action->handler);
0217         if (action->thread_fn)
0218             printk(KERN_CONT " threaded [<%p>] %ps",
0219                     action->thread_fn, action->thread_fn);
0220         printk(KERN_CONT "\n");
0221     }
0222     raw_spin_unlock_irqrestore(&desc->lock, flags);
0223 }
0224
0225 static void report_bad_irq(struct irq_desc *desc, irqreturn_t action_ret)
0226 {
0227     static int count = 100;
0228
0229     if (count > 0) {
0230         count--;
0231         __report_bad_irq(desc, action_ret);
0232     }
0233 }
0234
0235 static inline int
0236 try_misrouted_irq(unsigned int irq, struct irq_desc *desc,
0237           irqreturn_t action_ret)
0238 {
0239     struct irqaction *action;
0240
0241     if (!irqfixup)
0242         return 0;
0243
0244     /* We didn't actually handle the IRQ - see if it was misrouted? */
0245     if (action_ret == IRQ_NONE)
0246         return 1;
0247
0248     /*
0249      * But for 'irqfixup == 2' we also do it for handled interrupts if
0250      * they are marked as IRQF_IRQPOLL (or for irq zero, which is the
0251      * traditional PC timer interrupt.. Legacy)
0252      */
0253     if (irqfixup < 2)
0254         return 0;
0255
0256     if (!irq)
0257         return 1;
0258
0259     /*
0260      * Since we don't get the descriptor lock, "action" can
0261      * change under us.  We don't really care, but we don't
0262      * want to follow a NULL pointer. So tell the compiler to
0263      * just load it once by using a barrier.
0264      */
0265     action = desc->action;
0266     barrier();
0267     return action && (action->flags & IRQF_IRQPOLL);
0268 }
0269
0270 #define SPURIOUS_DEFERRED   0x80000000
0271
0272 void note_interrupt(struct irq_desc *desc, irqreturn_t action_ret)
0273 {
0274     unsigned int irq;
0275
0276     if (desc->istate & IRQS_POLL_INPROGRESS ||
0277         irq_settings_is_polled(desc))
0278         return;
0279
0280     if (bad_action_ret(action_ret)) {
0281         report_bad_irq(desc, action_ret);
0282         return;
0283     }
0284
0285     /*
0286      * We cannot call note_interrupt from the threaded handler
0287      * because we need to look at the compound of all handlers
0288      * (primary and threaded). Aside of that in the threaded
0289      * shared case we have no serialization against an incoming
0290      * hardware interrupt while we are dealing with a threaded
0291      * result.
0292      *
0293      * So in case a thread is woken, we just note the fact and
0294      * defer the analysis to the next hardware interrupt.
0295      *
0296      * The threaded handlers store whether they successfully
0297      * handled an interrupt and we check whether that number
0298      * changed versus the last invocation.
0299      *
0300      * We could handle all interrupts with the delayed by one
0301      * mechanism, but for the non forced threaded case we'd just
0302      * add pointless overhead to the straight hardirq interrupts
0303      * for the sake of a few lines less code.
0304      */
0305     if (action_ret & IRQ_WAKE_THREAD) {
0306         /*
0307          * There is a thread woken. Check whether one of the
0308          * shared primary handlers returned IRQ_HANDLED. If
0309          * not we defer the spurious detection to the next
0310          * interrupt.
0311          */
0312         if (action_ret == IRQ_WAKE_THREAD) {
0313             int handled;
0314             /*
0315              * We use bit 31 of thread_handled_last to
0316              * denote the deferred spurious detection
0317              * active. No locking necessary as
0318              * thread_handled_last is only accessed here
0319              * and we have the guarantee that hard
0320              * interrupts are not reentrant.
0321              */
0322             if (!(desc->threads_handled_last & SPURIOUS_DEFERRED)) {
0323                 desc->threads_handled_last |= SPURIOUS_DEFERRED;
0324                 return;
0325             }
0326             /*
0327              * Check whether one of the threaded handlers
0328              * returned IRQ_HANDLED since the last
0329              * interrupt happened.
0330              *
0331              * For simplicity we just set bit 31, as it is
0332              * set in threads_handled_last as well. So we
0333              * avoid extra masking. And we really do not
0334              * care about the high bits of the handled
0335              * count. We just care about the count being
0336              * different than the one we saw before.
0337              */
0338             handled = atomic_read(&desc->threads_handled);
0339             handled |= SPURIOUS_DEFERRED;
0340             if (handled != desc->threads_handled_last) {
0341                 action_ret = IRQ_HANDLED;
0342                 /*
0343                  * Note: We keep the SPURIOUS_DEFERRED
0344                  * bit set. We are handling the
0345                  * previous invocation right now.
0346                  * Keep it for the current one, so the
0347                  * next hardware interrupt will
0348                  * account for it.
0349                  */
0350                 desc->threads_handled_last = handled;
0351             } else {
0352                 /*
0353                  * None of the threaded handlers felt
0354                  * responsible for the last interrupt
0355                  *
0356                  * We keep the SPURIOUS_DEFERRED bit
0357                  * set in threads_handled_last as we
0358                  * need to account for the current
0359                  * interrupt as well.
0360                  */
0361                 action_ret = IRQ_NONE;
0362             }
0363         } else {
0364             /*
0365              * One of the primary handlers returned
0366              * IRQ_HANDLED. So we don't care about the
0367              * threaded handlers on the same line. Clear
0368              * the deferred detection bit.
0369              *
0370              * In theory we could/should check whether the
0371              * deferred bit is set and take the result of
0372              * the previous run into account here as
0373              * well. But it's really not worth the
0374              * trouble. If every other interrupt is
0375              * handled we never trigger the spurious
0376              * detector. And if this is just the one out
0377              * of 100k unhandled ones which is handled
0378              * then we merily delay the spurious detection
0379              * by one hard interrupt. Not a real problem.
0380              */
0381             desc->threads_handled_last &= ~SPURIOUS_DEFERRED;
0382         }
0383     }
0384
0385     if (unlikely(action_ret == IRQ_NONE)) {
0386         /*
0387          * If we are seeing only the odd spurious IRQ caused by
0388          * bus asynchronicity then don't eventually trigger an error,
0389          * otherwise the counter becomes a doomsday timer for otherwise
0390          * working systems
0391          */
0392         if (time_after(jiffies, desc->last_unhandled + HZ/10))
0393             desc->irqs_unhandled = 1;
0394         else
0395             desc->irqs_unhandled++;
0396         desc->last_unhandled = jiffies;
0397     }
0398
0399     irq = irq_desc_get_irq(desc);
0400     if (unlikely(try_misrouted_irq(irq, desc, action_ret))) {
0401         int ok = misrouted_irq(irq);
0402         if (action_ret == IRQ_NONE)
0403             desc->irqs_unhandled -= ok;
0404     }
0405
0406     if (likely(!desc->irqs_unhandled))
0407         return;
0408
0409     /* Now getting into unhandled irq detection */
0410     desc->irq_count++;
0411     if (likely(desc->irq_count < 100000))
0412         return;
0413
0414     desc->irq_count = 0;
0415     if (unlikely(desc->irqs_unhandled > 99900)) {
0416         /*
0417          * The interrupt is stuck
0418          */
0419         __report_bad_irq(desc, action_ret);
0420         /*
0421          * Now kill the IRQ
0422          */
0423         printk(KERN_EMERG "Disabling IRQ #%d\n", irq);
0424         desc->istate |= IRQS_SPURIOUS_DISABLED;
0425         desc->depth++;
0426         irq_disable(desc);
0427
0428         mod_timer(&poll_spurious_irq_timer,
0429               jiffies + POLL_SPURIOUS_IRQ_INTERVAL);
0430     }
0431     desc->irqs_unhandled = 0;
0432 }
0433
0434 bool noirqdebug __read_mostly;
0435
0436 int noirqdebug_setup(char *str)
0437 {
0438     noirqdebug = 1;
0439     printk(KERN_INFO "IRQ lockup detection disabled\n");
0440
0441     return 1;
0442 }
0443
0444 __setup("noirqdebug", noirqdebug_setup);
0445 module_param(noirqdebug, bool, 0644);
0446 MODULE_PARM_DESC(noirqdebug, "Disable irq lockup detection when true");
0447
0448 static int __init irqfixup_setup(char *str)
0449 {
0450     if (IS_ENABLED(CONFIG_PREEMPT_RT)) {
0451         pr_warn("irqfixup boot option not supported with PREEMPT_RT\n");
0452         return 1;
0453     }
0454     irqfixup = 1;
0455     printk(KERN_WARNING "Misrouted IRQ fixup support enabled.\n");
0456     printk(KERN_WARNING "This may impact system performance.\n");
0457
0458     return 1;
0459 }
0460
0461 __setup("irqfixup", irqfixup_setup);
0462 module_param(irqfixup, int, 0644);
0463
0464 static int __init irqpoll_setup(char *str)
0465 {
0466     if (IS_ENABLED(CONFIG_PREEMPT_RT)) {
0467         pr_warn("irqpoll boot option not supported with PREEMPT_RT\n");
0468         return 1;
0469     }
0470     irqfixup = 2;
0471     printk(KERN_WARNING "Misrouted IRQ fixup and polling support "
0472                 "enabled\n");
0473     printk(KERN_WARNING "This may significantly impact system "
0474                 "performance\n");
0475     return 1;
0476 }
0477
0478 __setup("irqpoll", irqpoll_setup);