linux-kernel - Re: [PATCH] ads7846: fix unsafe disable_irq (was [REGRESSION] threaded interrupt handler support breaks (some) irq handling on AVR32)

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Message-ID: <20090416015826.GA2413@dtor-d630.eng.vmware.com>
Date:	Wed, 15 Apr 2009 18:58:27 -0700
From:	Dmitry Torokhov <dmitry.torokhov@...il.com>
To:	Ben Nizette <bn@...sdigital.com>
Cc:	tglx@...utronix.de, David Brownell <david-b@...bell.net>,
	hskinnemoen@...el.com, kernel@...32linux.org,
	linux-kernel@...r.kernel.org, imre.deak@...ia.com, mingo@...e.hu,
	Bill Gatliff <bgat@...lgatliff.com>,
	Haavard Skinnemoen <haavard.skinnemoen@...el.com>
Subject: Re: [PATCH] ads7846: fix unsafe disable_irq (was [REGRESSION]
	threaded interrupt handler support breaks (some) irq handling on
	AVR32)

On Thu, Apr 16, 2009 at 10:41:57AM +1000, Ben Nizette wrote:
> On Wed, 2009-04-15 at 09:57 +0200, Haavard Skinnemoen wrote:
> > Shouldn't that be disable_irq_nosync()?
> 
> Indeed, good catch.  That fixes it.
> 
> --------------8<--------------------
> 
> The use of disable_irq inside the handler for the interrupt being
> disabled has always been dangerous.  disable_irq should wait for that
> handler to complete before returning -> deadlock.
> 
> For some reason this wasn't actually the case until 3aa551c9b was merged
> but since this time, the ads7846 driver has deadlocked the system on
> first interrupt.
> 
> Convert the driver to use the handler-safe _nosync variant.
> 

Applied, thank you very much Ben.

-- 
Dmitry
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