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![Alan Cox](/assets/img/avatar_default.png)
Currently we handle spurious IRQ activity based upon seeing a lot of invalid interrupts, and we clear things back on the base of lots of valid interrupts. Unfortunately in some cases you get legitimate invalid interrupts caused by timing asynchronicity between the PCI bus and the APIC bus when disabling interrupts and pulling other tricks. In this case although the spurious IRQs are not a problem our unhandled counters didn't clear and they act as a slow running timebomb. (This is effectively what the serial port/tty problem that was fixed by clearing counters when registering a handler showed up) It's easy enough to add a second parameter - time. This means that if we see a regular stream of harmless spurious interrupts which are not harming processing we don't go off and do something stupid like disable the IRQ after a month of running. OTOH lockups and performance killers show up a lot more than 10/second [akpm@linux-foundation.org: cleanup] Signed-off-by: Alan Cox <alan@redhat.com> Cc: Ingo Molnar <mingo@elte.hu> Cc: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
250 lines
5.8 KiB
C
250 lines
5.8 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/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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static int irqfixup __read_mostly;
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/*
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* Recovery handler for misrouted interrupts.
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*/
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static int misrouted_irq(int irq)
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{
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int i;
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int ok = 0;
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int work = 0; /* Did we do work for a real IRQ */
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for (i = 1; i < NR_IRQS; i++) {
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struct irq_desc *desc = irq_desc + i;
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struct irqaction *action;
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if (i == irq) /* Already tried */
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continue;
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spin_lock(&desc->lock);
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/* Already running on another processor */
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if (desc->status & IRQ_INPROGRESS) {
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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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if (desc->action && (desc->action->flags & IRQF_SHARED))
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desc->status |= IRQ_PENDING;
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spin_unlock(&desc->lock);
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continue;
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}
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/* Honour the normal IRQ locking */
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desc->status |= IRQ_INPROGRESS;
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action = desc->action;
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spin_unlock(&desc->lock);
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while (action) {
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/* Only shared IRQ handlers are safe to call */
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if (action->flags & IRQF_SHARED) {
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if (action->handler(i, action->dev_id) ==
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IRQ_HANDLED)
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ok = 1;
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}
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action = action->next;
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}
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local_irq_disable();
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/* Now clean up the flags */
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spin_lock(&desc->lock);
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action = desc->action;
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/*
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* While we were looking for a fixup someone queued a real
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* IRQ clashing with our walk:
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*/
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while ((desc->status & IRQ_PENDING) && action) {
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/*
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* Perform real IRQ processing for the IRQ we deferred
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*/
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work = 1;
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spin_unlock(&desc->lock);
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handle_IRQ_event(i, action);
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spin_lock(&desc->lock);
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desc->status &= ~IRQ_PENDING;
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}
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desc->status &= ~IRQ_INPROGRESS;
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/*
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* If we did actual work for the real IRQ line we must let the
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* IRQ controller clean up too
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*/
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if (work && desc->chip && desc->chip->end)
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desc->chip->end(i);
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spin_unlock(&desc->lock);
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}
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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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/*
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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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* Called under desc->lock
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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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if (action_ret != IRQ_HANDLED && action_ret != IRQ_NONE) {
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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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action = desc->action;
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while (action) {
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printk(KERN_ERR "[<%p>]", action->handler);
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print_symbol(" (%s)",
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(unsigned long)action->handler);
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printk("\n");
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action = action->next;
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}
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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 try_misrouted_irq(unsigned int irq, struct irq_desc *desc, 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 (unlikely(action_ret != IRQ_HANDLED)) {
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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 couter becomes a doomsday timer for otherwise
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* working systems
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*/
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if (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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if (unlikely(action_ret != IRQ_NONE))
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report_bad_irq(irq, desc, action_ret);
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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->status |= IRQ_DISABLED;
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desc->depth = 1;
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desc->chip->disable(irq);
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}
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desc->irqs_unhandled = 0;
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}
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int 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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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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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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