linux-kernel - Re: [PATCH] sdhci: Fix potential spinlock recursion

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Message-ID: <20090115070521.25c3bda7@mjolnir.drzeus.cx>
Date:	Thu, 15 Jan 2009 07:05:21 +0100
From:	Pierre Ossman <drzeus@...eus.cx>
To:	Anton Vorontsov <avorontsov@...mvista.com>
Cc:	sdhci-devel@...t.drzeus.cx, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] sdhci: Fix potential spinlock recursion

On Wed, 14 Jan 2009 22:41:59 +0300
Anton Vorontsov <avorontsov@...mvista.com> wrote:

> 
> This happens because plain spin_lock() won't protect us from
> softirqs (tasklets). So in the sdhci interrupt handler we must
> grab the _irq version of the lock.
> 

?! The docs I've read state that softirq:s are not executed until all
the hardirq:s have finished processing. And looking at your code, that
seems to still hold true. A softirq running esdhc_tasklet_card() gets
preempted by a hard irq and we have the lockup.

If you're running the code you sent a few minutes later, then something
is broken with your platform as esdhc_tasklet_card() clearly tries to
disable interrupts when it grabs the lock.

Rgds
-- 
     -- Pierre Ossman

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