linux-kernel - Re: Logitech USB headset not working in 3.6-rc3

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Message-ID: <s5hsjb56d40.wl%tiwai@suse.de>
Date:	Wed, 29 Aug 2012 15:29:03 +0200
From:	Takashi Iwai <tiwai@...e.de>
To:	Daniel Mack <zonque@...il.com>
Cc:	Josh Boyer <jwboyer@...hat.com>, Bruno Wolff III <bruno@...ff.to>,
	Jaroslav Kysela <perex@...ex.cz>, alsa-devel@...a-project.org,
	linux-kernel@...r.kernel.org
Subject: Re: Logitech USB headset not working in 3.6-rc3

At Wed, 29 Aug 2012 13:26:25 +0200,
Daniel Mack wrote:
> 
> [1  <text/plain; ISO-8859-1 (7bit)>]
> On 25.08.2012 14:17, Josh Boyer wrote:
> > On Sat, Aug 25, 2012 at 02:13:58PM +0200, Daniel Mack wrote:
> >> On 25.08.2012 14:07, Bruno Wolff III wrote:
> >>> On Sat, Aug 25, 2012 at 14:02:51 +0200,
> >>>    Daniel Mack <zonque@...il.com> wrote:
> >>>>
> >>>> Can you revert commit e9ba389c5 ("ALSA: usb-audio: Fix
> >>>> scheduling-while-atomic bug in PCM capture stream") and see if that
> >>>
> >>> I can try that, but it takes a long time to build a new kernel on my 
> >>> old hardware.
> >>>
> >>>> helps? If not, can you summarize again which kernels still work for you
> >>>> and which don't?
> >>>
> >>> The latest kernel that works is 3.6.0-0.rc2.git1.2.fc18. The earliest that 
> >>> doesn't work is 3.6.0-0.rc2.git2.1.fc18.
> >>>
> >>
> >> The report you sent doesn't look like it could be caused by e9ba389c5.
> >> It fixes a kernel Ooops. But as it is the only relevant patch in that
> >> area, it would be interesting if reverting it fixes anything.
> > 
> > Yep, agreed.  If this revert kernel doesn't work, we're likely down to a
> > git bisect, Bruno.
> > 
> >> Btw - thanks a lot for testing -rc kernels, much appreciated!
> > 
> > Indeed!
> 
> Could you please try this patch on top of Takashi's? Thanks again!
> 
> 
> Daniel
> 
> [2 0001-ALSA-snd-usb-Fix-URB-cancellation-at-stream-start.patch <text/x-patch (7bit)>]
> >From 6617bb2463ae3fad21390b59cc2a71f96b9e9ca8 Mon Sep 17 00:00:00 2001
> From: Daniel Mack <zonque@...il.com>
> Date: Wed, 29 Aug 2012 13:17:05 +0200
> Subject: [PATCH] ALSA: snd-usb: Fix URB cancellation at stream start
> 
> Commit e9ba389c5 ("ALSA: usb-audio: Fix scheduling-while-atomic bug in
> PCM capture stream") fixed a scheduling-while-atomic bug that happened
> when snd_usb_endpoint_start was called from the trigger callback, which
> is an atmic context. However, the patch breaks the idea of the endpoints
> reference counting, which is the reason why the driver has been
> refactored lately.
> 
> Revert that commit and let snd_usb_endpoint_start() take care of the URB
> cancellation again. As this function is called from both atomic and
> non-atomic context, add a flag to denote whether the function may sleep.
> 
> Signed-off-by: Daniel Mack <zonque@...il.com>
> Cc: stable@...nel.org [3.5+]
> ---
>  sound/usb/endpoint.c | 10 ++++++++--
>  sound/usb/endpoint.h |  2 +-
>  sound/usb/pcm.c      | 13 +++++--------
>  3 files changed, 14 insertions(+), 11 deletions(-)
> 
> diff --git a/sound/usb/endpoint.c b/sound/usb/endpoint.c
> index c411812..678456c 100644
> --- a/sound/usb/endpoint.c
> +++ b/sound/usb/endpoint.c
> @@ -799,7 +799,9 @@ int snd_usb_endpoint_set_params(struct snd_usb_endpoint *ep,
>  /**
>   * snd_usb_endpoint_start: start an snd_usb_endpoint
>   *
> - * @ep: the endpoint to start
> + * @ep:		the endpoint to start
> + * @can_sleep:	flag indicating whether the operation is executed in
> + * 		non-atomic context
>   *
>   * A call to this function will increment the use count of the endpoint.
>   * In case it is not already running, the URBs for this endpoint will be
> @@ -809,7 +811,7 @@ int snd_usb_endpoint_set_params(struct snd_usb_endpoint *ep,
>   *
>   * Returns an error if the URB submission failed, 0 in all other cases.
>   */
> -int snd_usb_endpoint_start(struct snd_usb_endpoint *ep)
> +int snd_usb_endpoint_start(struct snd_usb_endpoint *ep, int can_sleep)
>  {
>  	int err;
>  	unsigned int i;
> @@ -821,6 +823,10 @@ int snd_usb_endpoint_start(struct snd_usb_endpoint *ep)
>  	if (++ep->use_count != 1)
>  		return 0;
>  
> +	/* just to be sure */
> +	deactivate_urbs(ep, 0, can_sleep);
> +	wait_clear_urbs(ep);

It'd be safer to protect the call of wait_clear_urbs() when
can_sleep=0.


thanks,

Takashi
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