linux-kernel - Re: [PATCH] warn about shared irqs requesting IRQF_DISABLED registered with setup

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Message-ID: <20091129102635.GA22653@pengutronix.de>
Date:	Sun, 29 Nov 2009 11:26:35 +0100
From:	Uwe Kleine-König 
	<u.kleine-koenig@...gutronix.de>
To:	Jamie Lokier <jamie@...reable.org>
Cc:	Thomas Gleixner <tglx@...utronix.de>,
	Rusty Russell <rusty@...tcorp.com.au>,
	David Brownell <dbrownell@...rs.sourceforge.net>,
	Eric Miao <eric.y.miao@...il.com>,
	Peter Zijlstra <a.p.zijlstra@...llo.nl>,
	John Stultz <johnstul@...ibm.com>,
	Nicolas Pitre <nico@...vell.com>,
	LKML <linux-kernel@...r.kernel.org>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Ingo Molnar <mingo@...e.hu>,
	linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH] warn about shared irqs requesting IRQF_DISABLED
	registered with setup_irq

Hello,

On Sun, Nov 29, 2009 at 02:31:18AM +0000, Jamie Lokier wrote:
> Thomas Gleixner wrote:
> > What about analysing the code and verifying that the setup order is
> > correct ?
> > 
> > Adding save/restore_irq just because you have no clue what the code
> > does is utter nonsense.
> 
> Wouldn't it be quite a lot nicer if generic setup moved the
> IRQF_DISABLED handler to be first in the list, if that actually works
> in a useful way rather than simply being a quirk that irqs are
> disabled for the first one?
Hmm, what happens if an ISR runs with irqs disabled even though it
doesn't expect it?  I wouldn't bet that nothing breaks.

IMHO the best is if a warning is printed or registering fails if shared
irq actions don't agree about wanting IRQF_DISABLED.

Best regards
Uwe

-- 
Pengutronix e.K.                              | Uwe Kleine-König            |
Industrial Linux Solutions                    | http://www.pengutronix.de/  |
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