Date: Mon, 23 Jun 2008 14:18:42 +0200
Message-ID: <s5hskv42vkt.wl%tiwai@suse.de>
From: Takashi Iwai <tiwai@suse.de>
To: Marcin Slusarz <marcin.slusarz@gmail.com>
Cc: Cedric Bregardis <cedric.bregardis@free.fr>,
       Jean-Christian Hassler <jhassler@free.fr>,
       LKML <linux-kernel@vger.kernel.org>
Subject: Re: oops in Audiowerk2 ALSA driver
In-Reply-To: <20080622164443.GA7208@joi>
References: <20080622164443.GA7208@joi>
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At Sun, 22 Jun 2008 18:47:17 +0200,
Marcin Slusarz wrote:
> 
> Hi
> There's a race between registration routine and interrupt handler in aw2 driver
> which manifested as oops on some box [1].
> 
> When snd_aw2_create calls request_irq chip data are not yet fully initialized.
> If interrupt raises before snd_aw2_create call snd_aw2_saa7146_setup, driver may
> oops or read/write other port than its own. (chip->base_addr is initialized in
> snd_aw2_saa7146_setup, but is used in snd_aw2_saa7146_interrupt via READREG/WRITEREG)
> 
> The simple fix would be to move call to snd_aw2_saa7146_setup before request_irq,
> but snd_aw2_saa7146_setup enables interrupts...
> 
> PS: I don't have this hardware.
> 
> Marcin
> 
> [1] http://kerneloops.org/guilty.php?guilty=snd_aw2_saa7146_interrupt&version=2.6.26-rc&start=1703936&end=1736703&class=oops

Thanks for spotting the bug.
I fixed this on my git tree now and will post a pull request soon
later.


Takashi
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