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![Thomas Gleixner](/assets/img/avatar_default.png)
On a 68k platform a couple of interrupts are demultiplexed and "polled" from a top level interrupt. Unfortunately there is no way to determine which of the sub interrupts raised the top level interrupt, so all of the demultiplexed interrupt handlers need to be invoked. Given a high enough frequency this can trigger the spurious interrupt detection mechanism, if one of the demultiplex interrupts returns IRQ_NONE continuously. But this is a false positive as the polling causes this behaviour and not buggy hardware/software. Introduce IRQ_POLLED which can be set at interrupt chip setup time via irq_set_status_flags(). The flag excludes the interrupt from the spurious detector and from all core polling activities. Reported-and-tested-by: Michael Schmitz <schmitzmic@gmail.com> Cc: Geert Uytterhoeven <geert@linux-m68k.org> Cc: linux-m68k@vger.kernel.org Link: http://lkml.kernel.org/r/alpine.DEB.2.02.1311061149250.23353@ionos.tec.linutronix.de
369 lines
8.7 KiB
C
369 lines
8.7 KiB
C
/*
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* linux/kernel/irq/spurious.c
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*
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* Copyright (C) 1992, 1998-2004 Linus Torvalds, Ingo Molnar
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*
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* This file contains spurious interrupt handling.
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*/
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#include <linux/jiffies.h>
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#include <linux/irq.h>
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#include <linux/module.h>
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#include <linux/kallsyms.h>
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#include <linux/interrupt.h>
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#include <linux/moduleparam.h>
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#include <linux/timer.h>
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#include "internals.h"
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static int irqfixup __read_mostly;
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#define POLL_SPURIOUS_IRQ_INTERVAL (HZ/10)
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static void poll_spurious_irqs(unsigned long dummy);
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static DEFINE_TIMER(poll_spurious_irq_timer, poll_spurious_irqs, 0, 0);
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static int irq_poll_cpu;
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static atomic_t irq_poll_active;
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/*
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* We wait here for a poller to finish.
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*
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* If the poll runs on this CPU, then we yell loudly and return
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* false. That will leave the interrupt line disabled in the worst
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* case, but it should never happen.
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*
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* We wait until the poller is done and then recheck disabled and
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* action (about to be disabled). Only if it's still active, we return
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* true and let the handler run.
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*/
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bool irq_wait_for_poll(struct irq_desc *desc)
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{
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if (WARN_ONCE(irq_poll_cpu == smp_processor_id(),
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"irq poll in progress on cpu %d for irq %d\n",
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smp_processor_id(), desc->irq_data.irq))
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return false;
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#ifdef CONFIG_SMP
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do {
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raw_spin_unlock(&desc->lock);
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while (irqd_irq_inprogress(&desc->irq_data))
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cpu_relax();
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raw_spin_lock(&desc->lock);
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} while (irqd_irq_inprogress(&desc->irq_data));
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/* Might have been disabled in meantime */
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return !irqd_irq_disabled(&desc->irq_data) && desc->action;
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#else
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return false;
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#endif
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}
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/*
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* Recovery handler for misrouted interrupts.
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*/
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static int try_one_irq(int irq, struct irq_desc *desc, bool force)
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{
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irqreturn_t ret = IRQ_NONE;
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struct irqaction *action;
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raw_spin_lock(&desc->lock);
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/*
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* PER_CPU, nested thread interrupts and interrupts explicitely
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* marked polled are excluded from polling.
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*/
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if (irq_settings_is_per_cpu(desc) ||
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irq_settings_is_nested_thread(desc) ||
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irq_settings_is_polled(desc))
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goto out;
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/*
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* Do not poll disabled interrupts unless the spurious
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* disabled poller asks explicitely.
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*/
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if (irqd_irq_disabled(&desc->irq_data) && !force)
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goto out;
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/*
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* All handlers must agree on IRQF_SHARED, so we test just the
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* first.
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*/
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action = desc->action;
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if (!action || !(action->flags & IRQF_SHARED) ||
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(action->flags & __IRQF_TIMER))
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goto out;
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/* Already running on another processor */
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if (irqd_irq_inprogress(&desc->irq_data)) {
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/*
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* Already running: If it is shared get the other
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* CPU to go looking for our mystery interrupt too
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*/
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desc->istate |= IRQS_PENDING;
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goto out;
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}
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/* Mark it poll in progress */
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desc->istate |= IRQS_POLL_INPROGRESS;
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do {
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if (handle_irq_event(desc) == IRQ_HANDLED)
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ret = IRQ_HANDLED;
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/* Make sure that there is still a valid action */
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action = desc->action;
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} while ((desc->istate & IRQS_PENDING) && action);
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desc->istate &= ~IRQS_POLL_INPROGRESS;
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out:
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raw_spin_unlock(&desc->lock);
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return ret == IRQ_HANDLED;
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}
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static int misrouted_irq(int irq)
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{
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struct irq_desc *desc;
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int i, ok = 0;
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if (atomic_inc_return(&irq_poll_active) != 1)
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goto out;
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irq_poll_cpu = smp_processor_id();
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for_each_irq_desc(i, desc) {
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if (!i)
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continue;
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if (i == irq) /* Already tried */
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continue;
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if (try_one_irq(i, desc, false))
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ok = 1;
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}
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out:
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atomic_dec(&irq_poll_active);
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/* So the caller can adjust the irq error counts */
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return ok;
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}
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static void poll_spurious_irqs(unsigned long dummy)
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{
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struct irq_desc *desc;
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int i;
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if (atomic_inc_return(&irq_poll_active) != 1)
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goto out;
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irq_poll_cpu = smp_processor_id();
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for_each_irq_desc(i, desc) {
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unsigned int state;
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if (!i)
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continue;
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/* Racy but it doesn't matter */
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state = desc->istate;
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barrier();
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if (!(state & IRQS_SPURIOUS_DISABLED))
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continue;
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local_irq_disable();
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try_one_irq(i, desc, true);
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local_irq_enable();
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}
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out:
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atomic_dec(&irq_poll_active);
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mod_timer(&poll_spurious_irq_timer,
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jiffies + POLL_SPURIOUS_IRQ_INTERVAL);
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}
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static inline int bad_action_ret(irqreturn_t action_ret)
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{
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if (likely(action_ret <= (IRQ_HANDLED | IRQ_WAKE_THREAD)))
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return 0;
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return 1;
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}
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/*
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* If 99,900 of the previous 100,000 interrupts have not been handled
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* then assume that the IRQ is stuck in some manner. Drop a diagnostic
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* and try to turn the IRQ off.
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*
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* (The other 100-of-100,000 interrupts may have been a correctly
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* functioning device sharing an IRQ with the failing one)
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*/
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static void
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__report_bad_irq(unsigned int irq, struct irq_desc *desc,
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irqreturn_t action_ret)
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{
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struct irqaction *action;
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unsigned long flags;
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if (bad_action_ret(action_ret)) {
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printk(KERN_ERR "irq event %d: bogus return value %x\n",
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irq, action_ret);
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} else {
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printk(KERN_ERR "irq %d: nobody cared (try booting with "
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"the \"irqpoll\" option)\n", irq);
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}
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dump_stack();
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printk(KERN_ERR "handlers:\n");
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/*
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* We need to take desc->lock here. note_interrupt() is called
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* w/o desc->lock held, but IRQ_PROGRESS set. We might race
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* with something else removing an action. It's ok to take
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* desc->lock here. See synchronize_irq().
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*/
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raw_spin_lock_irqsave(&desc->lock, flags);
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action = desc->action;
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while (action) {
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printk(KERN_ERR "[<%p>] %pf", action->handler, action->handler);
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if (action->thread_fn)
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printk(KERN_CONT " threaded [<%p>] %pf",
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action->thread_fn, action->thread_fn);
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printk(KERN_CONT "\n");
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action = action->next;
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}
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raw_spin_unlock_irqrestore(&desc->lock, flags);
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}
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static void
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report_bad_irq(unsigned int irq, struct irq_desc *desc, irqreturn_t action_ret)
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{
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static int count = 100;
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if (count > 0) {
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count--;
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__report_bad_irq(irq, desc, action_ret);
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}
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}
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static inline int
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try_misrouted_irq(unsigned int irq, struct irq_desc *desc,
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irqreturn_t action_ret)
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{
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struct irqaction *action;
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if (!irqfixup)
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return 0;
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/* We didn't actually handle the IRQ - see if it was misrouted? */
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if (action_ret == IRQ_NONE)
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return 1;
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/*
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* But for 'irqfixup == 2' we also do it for handled interrupts if
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* they are marked as IRQF_IRQPOLL (or for irq zero, which is the
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* traditional PC timer interrupt.. Legacy)
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*/
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if (irqfixup < 2)
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return 0;
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if (!irq)
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return 1;
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/*
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* Since we don't get the descriptor lock, "action" can
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* change under us. We don't really care, but we don't
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* want to follow a NULL pointer. So tell the compiler to
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* just load it once by using a barrier.
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*/
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action = desc->action;
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barrier();
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return action && (action->flags & IRQF_IRQPOLL);
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}
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void note_interrupt(unsigned int irq, struct irq_desc *desc,
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irqreturn_t action_ret)
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{
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if (desc->istate & IRQS_POLL_INPROGRESS ||
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irq_settings_is_polled(desc))
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return;
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/* we get here again via the threaded handler */
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if (action_ret == IRQ_WAKE_THREAD)
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return;
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if (bad_action_ret(action_ret)) {
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report_bad_irq(irq, desc, action_ret);
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return;
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}
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if (unlikely(action_ret == IRQ_NONE)) {
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/*
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* If we are seeing only the odd spurious IRQ caused by
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* bus asynchronicity then don't eventually trigger an error,
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* otherwise the counter becomes a doomsday timer for otherwise
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* working systems
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*/
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if (time_after(jiffies, desc->last_unhandled + HZ/10))
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desc->irqs_unhandled = 1;
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else
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desc->irqs_unhandled++;
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desc->last_unhandled = jiffies;
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}
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if (unlikely(try_misrouted_irq(irq, desc, action_ret))) {
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int ok = misrouted_irq(irq);
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if (action_ret == IRQ_NONE)
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desc->irqs_unhandled -= ok;
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}
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desc->irq_count++;
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if (likely(desc->irq_count < 100000))
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return;
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desc->irq_count = 0;
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if (unlikely(desc->irqs_unhandled > 99900)) {
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/*
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* The interrupt is stuck
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*/
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__report_bad_irq(irq, desc, action_ret);
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/*
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* Now kill the IRQ
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*/
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printk(KERN_EMERG "Disabling IRQ #%d\n", irq);
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desc->istate |= IRQS_SPURIOUS_DISABLED;
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desc->depth++;
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irq_disable(desc);
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mod_timer(&poll_spurious_irq_timer,
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jiffies + POLL_SPURIOUS_IRQ_INTERVAL);
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}
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desc->irqs_unhandled = 0;
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}
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bool noirqdebug __read_mostly;
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int noirqdebug_setup(char *str)
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{
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noirqdebug = 1;
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printk(KERN_INFO "IRQ lockup detection disabled\n");
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return 1;
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}
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__setup("noirqdebug", noirqdebug_setup);
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module_param(noirqdebug, bool, 0644);
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MODULE_PARM_DESC(noirqdebug, "Disable irq lockup detection when true");
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static int __init irqfixup_setup(char *str)
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{
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irqfixup = 1;
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printk(KERN_WARNING "Misrouted IRQ fixup support enabled.\n");
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printk(KERN_WARNING "This may impact system performance.\n");
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return 1;
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}
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__setup("irqfixup", irqfixup_setup);
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module_param(irqfixup, int, 0644);
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static int __init irqpoll_setup(char *str)
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{
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irqfixup = 2;
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printk(KERN_WARNING "Misrouted IRQ fixup and polling support "
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"enabled\n");
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printk(KERN_WARNING "This may significantly impact system "
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"performance\n");
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return 1;
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}
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__setup("irqpoll", irqpoll_setup);
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