From: "Wang, Warner" <warner.wang@hp.com>
To: Thomas Gleixner <tglx@linutronix.de>,
        Edward Donovan <edward.donovan@numble.net>
CC: "Wang, Song-Bo (Stoney)" <song-bo.wang@hp.com>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: RE: need help on a DEADLOCK problem related to function
 try_one_irq()
Thread-Topic: need help on a DEADLOCK problem related to function
 try_one_irq()
Thread-Index: Ac3IBGPSFwpPXxP1Qcivc476N7zSdgAlyqwAAC+lMgAAlBlVYA==
Date: Mon, 26 Nov 2012 08:09:28 +0000
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References: <DAE2ECFDBE54434BA3014E0CC0F2A1E87700075B@G4W3211.americas.hpqcorp.net>
 <alpine.LFD.2.02.1211221120580.2701@ionos>
 <alpine.LFD.2.02.1211231008060.2701@ionos>
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Hi Thomas and Edward,

This patch works fine for our problems, but I'm not sure if it works for the recent submit "genirq: fix regression in irqfixup, irqpoll" "52553ddffad76ccf192d4dd9ce88d5818f57f62a", which submitted by Edward Donovan.

Edward can you help verify it on your environment?


Thanks,
-Warner

-----Original Message-----
From: Thomas Gleixner [mailto:tglx@linutronix.de] 
Sent: 2012??11??23?? PM 5:09
To: Wang, Warner
Cc: Wang, Song-Bo (Stoney)
Subject: Re: need help on a DEADLOCK problem related to function try_one_irq()

On Thu, 22 Nov 2012, Thomas Gleixner wrote:

> Warner,
> 
> On Thu, 22 Nov 2012, Wang, Warner wrote:
> 
> please send such bug reports to the kernel mailinglist in the future.
> 
> > We met a problem on some of our x86 server and after a few weeks 
> > trace-down effort, we believe the problem is in the file 
> > "linux/kernel/irq/spurious.c".  We created a patch but we are not 
> > 100% sure if it is correct or complete.  That is why we want to 
> > consult you.
> 
> You spotted the problem right, but I'm not sure at the first glance, 
> whether this is correct. I need to go back into history and figure out 
> why we added that call in the first place. It looks fundamentally 
> wrong.
> 
> Thanks for analyzing it. I'll keep you posted on my findings.

Can you try the patch below ?

Thanks,

	tglx

---
 kernel/irq/spurious.c |    8 +++-----
 1 file changed, 3 insertions(+), 5 deletions(-)

Index: tip/kernel/irq/spurious.c
===================================================================
--- tip.orig/kernel/irq/spurious.c
+++ tip/kernel/irq/spurious.c
@@ -80,13 +80,11 @@ static int try_one_irq(int irq, struct i
 
 	/*
 	 * All handlers must agree on IRQF_SHARED, so we test just the
-	 * first. Check for action->next as well.
+	 * first.
 	 */
 	action = desc->action;
 	if (!action || !(action->flags & IRQF_SHARED) ||
-	    (action->flags & __IRQF_TIMER) ||
-	    (action->handler(irq, action->dev_id) == IRQ_HANDLED) ||
-	    !action->next)
+	    (action->flags & __IRQF_TIMER))
 		goto out;
 
 	/* Already running on another processor */ @@ -104,7 +102,7 @@ static int try_one_irq(int irq, struct i
 	do {
 		if (handle_irq_event(desc) == IRQ_HANDLED)
 			ret = IRQ_HANDLED;
-		action = desc->action;
+		action = action->next;
 	} while ((desc->istate & IRQS_PENDING) && action);
 	desc->istate &= ~IRQS_POLL_INPROGRESS;
 out:
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