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Commit f84dbb91 authored by Eric W. Biederman's avatar Eric W. Biederman Committed by Ingo Molnar
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genirq: enable polling for disabled screaming irqs 



When we disable a screaming irq we never see it again.  If the irq
line is shared or if the driver half works this is a real pain.  So
periodically poll the handlers for screaming interrupts.

I use a timer instead of the classic irq poll technique of working off
the timer interrupt because when we use the local apic timers
note_interrupt is never called (bug?).  Further on a system with
dynamic ticks the timer interrupt might not even fire unless there is
a timer telling it it needs to.

I forced this case on my test system with an e1000 nic and my ssh
session remained responsive despite the interrupt handler only being
called every 10th of a second.

Signed-off-by: default avatarEric W. Biederman <ebiederm@xmission.com>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
parent 5b664cb2

kernel/irq/spurious.c

+91 −55
Original line number Diff line number Diff line
@@ -12,25 +12,23 @@ 
#include <linux/kallsyms.h>

#include <linux/interrupt.h>

#include <linux/moduleparam.h>

#include <linux/timer.h>



static int irqfixup __read_mostly;



#define POLL_SPURIOUS_IRQ_INTERVAL (HZ/10)

static void poll_spurious_irqs(unsigned long dummy);

static DEFINE_TIMER(poll_spurious_irq_timer, poll_spurious_irqs, 0, 0);



/*

 * Recovery handler for misrouted interrupts.

 */

static int misrouted_irq(int irq)

static int try_one_irq(int irq, struct irq_desc *desc)

{

	int i;

	struct irqaction *action;

	int ok = 0;

	int work = 0;	/* Did we do work for a real IRQ */



	for (i = 1; i < NR_IRQS; i++) {

		struct irq_desc *desc = irq_desc + i;

		struct irqaction *action;



		if (i == irq)	/* Already tried */

			continue;



	spin_lock(&desc->lock);

	/* Already running on another processor */

	if (desc->status & IRQ_INPROGRESS) {
@@ -41,7 +39,7 @@ static int misrouted_irq(int irq) 
		if (desc->action && (desc->action->flags & IRQF_SHARED))

			desc->status |= IRQ_PENDING;

		spin_unlock(&desc->lock);

			continue;

		return ok;

	}

	/* Honour the normal IRQ locking */

	desc->status |= IRQ_INPROGRESS;
@@ -51,7 +49,7 @@ static int misrouted_irq(int irq) 
	while (action) {

		/* Only shared IRQ handlers are safe to call */

		if (action->flags & IRQF_SHARED) {

				if (action->handler(i, action->dev_id) ==

			if (action->handler(irq, action->dev_id) ==

				IRQ_HANDLED)

				ok = 1;

		}
@@ -72,7 +70,7 @@ static int misrouted_irq(int irq) 
		 */

		work = 1;

		spin_unlock(&desc->lock);

			handle_IRQ_event(i, action);

		handle_IRQ_event(irq, action);

		spin_lock(&desc->lock);

		desc->status &= ~IRQ_PENDING;

	}
@@ -82,13 +80,49 @@ static int misrouted_irq(int irq) 
	 * IRQ controller clean up too

	 */

	if (work && desc->chip && desc->chip->end)

			desc->chip->end(i);

		desc->chip->end(irq);

	spin_unlock(&desc->lock);



	return ok;

}



static int misrouted_irq(int irq)

{

	int i;

	int ok = 0;



	for (i = 1; i < NR_IRQS; i++) {

		struct irq_desc *desc = irq_desc + i;



		if (i == irq)	/* Already tried */

			continue;



		if (try_one_irq(i, desc))

			ok = 1;

	}

	/* So the caller can adjust the irq error counts */

	return ok;

}



static void poll_spurious_irqs(unsigned long dummy)

{

	int i;

	for (i = 1; i < NR_IRQS; i++) {

		struct irq_desc *desc = irq_desc + i;

		unsigned int status;



		/* Racy but it doesn't matter */

		status = desc->status;

		barrier();

		if (!(status & IRQ_SPURIOUS_DISABLED))

			continue;



		try_one_irq(i, desc);

	}



	mod_timer(&poll_spurious_irq_timer, jiffies + POLL_SPURIOUS_IRQ_INTERVAL);

}



/*

 * If 99,900 of the previous 100,000 interrupts have not been handled

 * then assume that the IRQ is stuck in some manner. Drop a diagnostic
@@ -212,6 +246,8 @@ void note_interrupt(unsigned int irq, struct irq_desc *desc, 
		desc->status |= IRQ_DISABLED | IRQ_SPURIOUS_DISABLED;

		desc->depth++;

		desc->chip->disable(irq);



		mod_timer(&poll_spurious_irq_timer, jiffies + POLL_SPURIOUS_IRQ_INTERVAL);

	}

	desc->irqs_unhandled = 0;

}