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
  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);
  24static int irq_poll_cpu;
  25static 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 */
  38bool 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 */
  63static int try_one_irq(int 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        /* PER_CPU and nested thread interrupts are never polled */
  71        if (irq_settings_is_per_cpu(desc) || irq_settings_is_nested_thread(desc))
  72                goto out;
  73
  74        /*
  75         * Do not poll disabled interrupts unless the spurious
  76         * disabled poller asks explicitely.
  77         */
  78        if (irqd_irq_disabled(&desc->irq_data) && !force)
  79                goto out;
  80
  81        /*
  82         * All handlers must agree on IRQF_SHARED, so we test just the
  83         * first. Check for action->next as well.
  84         */
  85        action = desc->action;
  86        if (!action || !(action->flags & IRQF_SHARED) ||
  87            (action->flags & __IRQF_TIMER) ||
  88            (action->handler(irq, action->dev_id) == IRQ_HANDLED) ||
  89            !action->next)
  90                goto out;
  91
  92        /* Already running on another processor */
  93        if (irqd_irq_inprogress(&desc->irq_data)) {
  94                /*
  95                 * Already running: If it is shared get the other
  96                 * CPU to go looking for our mystery interrupt too
  97                 */
  98                desc->istate |= IRQS_PENDING;
  99                goto out;
 100        }
 101
 102        /* Mark it poll in progress */
 103        desc->istate |= IRQS_POLL_INPROGRESS;
 104        do {
 105                if (handle_irq_event(desc) == IRQ_HANDLED)
 106                        ret = IRQ_HANDLED;
 107                action = desc->action;
 108        } while ((desc->istate & IRQS_PENDING) && action);
 109        desc->istate &= ~IRQS_POLL_INPROGRESS;
 110out:
 111        raw_spin_unlock(&desc->lock);
 112        return ret == IRQ_HANDLED;
 113}
 114
 115static int misrouted_irq(int irq)
 116{
 117        struct irq_desc *desc;
 118        int i, ok = 0;
 119
 120        if (atomic_inc_return(&irq_poll_active) != 1)
 121                goto out;
 122
 123        irq_poll_cpu = smp_processor_id();
 124
 125        for_each_irq_desc(i, desc) {
 126                if (!i)
 127                         continue;
 128
 129                if (i == irq)   /* Already tried */
 130                        continue;
 131
 132                if (try_one_irq(i, desc, false))
 133                        ok = 1;
 134        }
 135out:
 136        atomic_dec(&irq_poll_active);
 137        /* So the caller can adjust the irq error counts */
 138        return ok;
 139}
 140
 141static void poll_spurious_irqs(unsigned long dummy)
 142{
 143        struct irq_desc *desc;
 144        int i;
 145
 146        if (atomic_inc_return(&irq_poll_active) != 1)
 147                goto out;
 148        irq_poll_cpu = smp_processor_id();
 149
 150        for_each_irq_desc(i, desc) {
 151                unsigned int state;
 152
 153                if (!i)
 154                         continue;
 155
 156                /* Racy but it doesn't matter */
 157                state = desc->istate;
 158                barrier();
 159                if (!(state & IRQS_SPURIOUS_DISABLED))
 160                        continue;
 161
 162                local_irq_disable();
 163                try_one_irq(i, desc, true);
 164                local_irq_enable();
 165        }
 166out:
 167        atomic_dec(&irq_poll_active);
 168        mod_timer(&poll_spurious_irq_timer,
 169                  jiffies + POLL_SPURIOUS_IRQ_INTERVAL);
 170}
 171
 172static inline int bad_action_ret(irqreturn_t action_ret)
 173{
 174        if (likely(action_ret <= (IRQ_HANDLED | IRQ_WAKE_THREAD)))
 175                return 0;
 176        return 1;
 177}
 178
 179/*
 180 * If 99,900 of the previous 100,000 interrupts have not been handled
 181 * then assume that the IRQ is stuck in some manner. Drop a diagnostic
 182 * and try to turn the IRQ off.
 183 *
 184 * (The other 100-of-100,000 interrupts may have been a correctly
 185 *  functioning device sharing an IRQ with the failing one)
 186 */
 187static void
 188__report_bad_irq(unsigned int irq, struct irq_desc *desc,
 189                 irqreturn_t action_ret)
 190{
 191        struct irqaction *action;
 192        unsigned long flags;
 193
 194        if (bad_action_ret(action_ret)) {
 195                printk(KERN_ERR "irq event %d: bogus return value %x\n",
 196                                irq, action_ret);
 197        } else {
 198                printk(KERN_ERR "irq %d: nobody cared (try booting with "
 199                                "the \"irqpoll\" option)\n", irq);
 200        }
 201        dump_stack();
 202        printk(KERN_ERR "handlers:\n");
 203
 204        /*
 205         * We need to take desc->lock here. note_interrupt() is called
 206         * w/o desc->lock held, but IRQ_PROGRESS set. We might race
 207         * with something else removing an action. It's ok to take
 208         * desc->lock here. See synchronize_irq().
 209         */
 210        raw_spin_lock_irqsave(&desc->lock, flags);
 211        action = desc->action;
 212        while (action) {
 213                printk(KERN_ERR "[<%p>] %pf", action->handler, action->handler);
 214                if (action->thread_fn)
 215                        printk(KERN_CONT " threaded [<%p>] %pf",
 216                                        action->thread_fn, action->thread_fn);
 217                printk(KERN_CONT "\n");
 218                action = action->next;
 219        }
 220        raw_spin_unlock_irqrestore(&desc->lock, flags);
 221}
 222
 223static void
 224report_bad_irq(unsigned int irq, struct irq_desc *desc, irqreturn_t action_ret)
 225{
 226        static int count = 100;
 227
 228        if (count > 0) {
 229                count--;
 230                __report_bad_irq(irq, desc, action_ret);
 231        }
 232}
 233
 234static inline int
 235try_misrouted_irq(unsigned int irq, struct irq_desc *desc,
 236                  irqreturn_t action_ret)
 237{
 238        struct irqaction *action;
 239
 240        if (!irqfixup)
 241                return 0;
 242
 243        /* We didn't actually handle the IRQ - see if it was misrouted? */
 244        if (action_ret == IRQ_NONE)
 245                return 1;
 246
 247        /*
 248         * But for 'irqfixup == 2' we also do it for handled interrupts if
 249         * they are marked as IRQF_IRQPOLL (or for irq zero, which is the
 250         * traditional PC timer interrupt.. Legacy)
 251         */
 252        if (irqfixup < 2)
 253                return 0;
 254
 255        if (!irq)
 256                return 1;
 257
 258        /*
 259         * Since we don't get the descriptor lock, "action" can
 260         * change under us.  We don't really care, but we don't
 261         * want to follow a NULL pointer. So tell the compiler to
 262         * just load it once by using a barrier.
 263         */
 264        action = desc->action;
 265        barrier();
 266        return action && (action->flags & IRQF_IRQPOLL);
 267}
 268
 269void note_interrupt(unsigned int irq, struct irq_desc *desc,
 270                    irqreturn_t action_ret)
 271{
 272        if (desc->istate & IRQS_POLL_INPROGRESS)
 273                return;
 274
 275        /* we get here again via the threaded handler */
 276        if (action_ret == IRQ_WAKE_THREAD)
 277                return;
 278
 279        if (bad_action_ret(action_ret)) {
 280                report_bad_irq(irq, desc, action_ret);
 281                return;
 282        }
 283
 284        if (unlikely(action_ret == IRQ_NONE)) {
 285                /*
 286                 * If we are seeing only the odd spurious IRQ caused by
 287                 * bus asynchronicity then don't eventually trigger an error,
 288                 * otherwise the counter becomes a doomsday timer for otherwise
 289                 * working systems
 290                 */
 291                if (time_after(jiffies, desc->last_unhandled + HZ/10))
 292                        desc->irqs_unhandled = 1;
 293                else
 294                        desc->irqs_unhandled++;
 295                desc->last_unhandled = jiffies;
 296        }
 297
 298        if (unlikely(try_misrouted_irq(irq, desc, action_ret))) {
 299                int ok = misrouted_irq(irq);
 300                if (action_ret == IRQ_NONE)
 301                        desc->irqs_unhandled -= ok;
 302        }
 303
 304        desc->irq_count++;
 305        if (likely(desc->irq_count < 100000))
 306                return;
 307
 308        desc->irq_count = 0;
 309        if (unlikely(desc->irqs_unhandled > 99900)) {
 310                /*
 311                 * The interrupt is stuck
 312                 */
 313                __report_bad_irq(irq, desc, action_ret);
 314                /*
 315                 * Now kill the IRQ
 316                 */
 317                printk(KERN_EMERG "Disabling IRQ #%d\n", irq);
 318                desc->istate |= IRQS_SPURIOUS_DISABLED;
 319                desc->depth++;
 320                irq_disable(desc);
 321
 322                mod_timer(&poll_spurious_irq_timer,
 323                          jiffies + POLL_SPURIOUS_IRQ_INTERVAL);
 324        }
 325        desc->irqs_unhandled = 0;
 326}
 327
 328bool noirqdebug __read_mostly;
 329
 330int noirqdebug_setup(char *str)
 331{
 332        noirqdebug = 1;
 333        printk(KERN_INFO "IRQ lockup detection disabled\n");
 334
 335        return 1;
 336}
 337
 338__setup("noirqdebug", noirqdebug_setup);
 339module_param(noirqdebug, bool, 0644);
 340MODULE_PARM_DESC(noirqdebug, "Disable irq lockup detection when true");
 341
 342static int __init irqfixup_setup(char *str)
 343{
 344        irqfixup = 1;
 345        printk(KERN_WARNING "Misrouted IRQ fixup support enabled.\n");
 346        printk(KERN_WARNING "This may impact system performance.\n");
 347
 348        return 1;
 349}
 350
 351__setup("irqfixup", irqfixup_setup);
 352module_param(irqfixup, int, 0644);
 353
 354static int __init irqpoll_setup(char *str)
 355{
 356        irqfixup = 2;
 357        printk(KERN_WARNING "Misrouted IRQ fixup and polling support "
 358                                "enabled\n");
 359        printk(KERN_WARNING "This may significantly impact system "
 360                                "performance\n");
 361        return 1;
 362}
 363
 364__setup("irqpoll", irqpoll_setup);
 365
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