Re: [PATCH] Reset file->f_op in snd_card_file_remove()

Re: [PATCH] Reset file->f_op in snd_card_file_remove()

[Takashi Iwai]

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@yahoo.de>

snd_card_file_remove() is not a right place to do that, IMO.

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.


Takashi
> 
> 
> 
> --- rt3/sound/core/init.c	2006-09-23 20:03:18.000000000 +0200
> +++ rt3-kw/sound/core/init.c	2006-09-27 20:44:54.000000000 +0200
> @@ -722,6 +722,7 @@ int snd_card_file_remove(struct snd_card
>  	mfile = card->files;
>  	while (mfile) {
>  		if (mfile->file == file) {
> +			file->f_op = NULL;
>  			if (pfile)
>  				pfile->next = mfile->next;
>  			else
> 
> 	
> 
> 	
> 		
> ___________________________________________________________ 
> Der frühe Vogel fängt den Wurm. Hier gelangen Sie zum neuen Yahoo! Mail: http://mail.yahoo.de
> 

Re: [PATCH] Reset file->f_op in snd_card_file_remove()

[karsten wiese]

--- Takashi Iwai <tiwai@suse.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@yahoo.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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Re: [Alsa-devel] [PATCH] Reset file->f_op in snd_card_file_remove()

[karsten wiese]

--- karsten wiese <annabellesgarden@yahoo.de> schrieb:
> i'm now running 2.6.18-rt3 + alsa-driver-1.0.13rc1 and problem seams to be gone.
> 
its alsa-driver-1.0.13rc3.

      Karsten


	

	
		
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Re: [Alsa-devel] [PATCH] Reset file->f_op in snd_card_file_remove()

[Takashi Iwai]

At Thu, 28 Sep 2006 13:39:06 +0200 (CEST),
karsten wiese wrote:
> 
> --- Takashi Iwai <tiwai@suse.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@yahoo.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.

Good to hear.  Thanks for confirmation!


Takashi