linux-kernel - Re: [PATCH] Reset file->f_op in snd_card_file

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Message-ID: <20060928113906.20550.qmail@web26504.mail.ukl.yahoo.com>
Date:	Thu, 28 Sep 2006 13:39:06 +0200 (CEST)
From:	karsten wiese <annabellesgarden@...oo.de>
To:	Takashi Iwai <tiwai@...e.de>
Cc:	mingo@...e.hu, alsa-devel@...ts.sourceforge.net,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] Reset file->f_op in snd_card_file_remove()

--- Takashi Iwai <tiwai@...e.de> schrieb:

> At Wed, 27 Sep 2006 21:27:51 +0200,
> Karsten Wiese wrote:
> > 
> > Hi
> > 
> > This patch helps prevent an oops on 2.6.18-rt3,
> > when my usb usx2y soundcard disconnects.
> > Physically disconnects or "rmmod uhci_hc" both oops 1in7.
> > 
> > With this patch still no oops after > 1000 disconnects.
> > 
> > Please apply/comment.
> > 
> >       thanks,
> >       Karsten
> > 
> > ===
> > 
> > Reset file->f_op in snd_card_file_remove()
> > 
> > When passing here in response to an usb disconnect,
> > file->f_op has been replaced with a kmalloc()ed version,
> > that would only allow releases.
> > 
> > It will be free()ed later on in snd_card_free().
> > Here it happened sometimes, that the free()ed, not NULLed file->f_op
> > caused an oops in module_put() called by fops_put() still later on.
> > 
> > Signed-off-by: Karsten Wiese <annabellesgarden@...oo.de>
> 
> snd_card_file_remove() is not a right place to do that, IMO.
> 
you are right, patch is wrong: it causes snd_hwdep's use count corruption.

> Could you check whether this problem still happens on post-2.6.18?
> There are a lot of fixes in this area after 2.6.18.
> 
i'm now running 2.6.18-rt3 + alsa-driver-1.0.13rc1 and problem seams to be gone.

      Karsten


	

	
		
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