linux-kernel - Re: [PATCH] ASoC: soc-pcm: Fix and cleanup DPCM locking

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Date:   Fri, 5 May 2023 19:42:44 +0900
From:   Greg KH <greg@...ah.com>
To:     yixuanjiang <yixuanjiang@...gle.com>
Cc:     tiwai@...e.com, lgirdwood@...il.com, broonie@...nel.org,
        linux-kernel@...r.kernel.org, alsa-devel@...a-project.org,
        Takashi Iwai <tiwai@...e.de>,
        Pierre-Louis Bossart <pierre-louis.bossart@...ux.intel.com>,
        Kai Vehmanen <kai.vehmanen@...ux.intel.com>,
        Bard Liao <yung-chuan.liao@...ux.intel.com>,
        Ranjani Sridharan <ranjani.sridharan@...ux.intel.com>,
        stable@...r.kernel.org
Subject: Re: [PATCH] ASoC: soc-pcm: Fix and cleanup DPCM locking

On Thu, May 04, 2023 at 05:21:42PM +0800, yixuanjiang wrote:
> From: Takashi Iwai <tiwai@...e.de>
> 
> The existing locking for DPCM has several issues
> a) a confusing mix of card->mutex and card->pcm_mutex.
> b) a dpcm_lock spinlock added inconsistently and on paths that could
> be recursively taken. The use of irqsave/irqrestore was also overkill.
> 
> The suggested model is:
> 
> 1) The pcm_mutex is the top-most protection of BE links in the FE. The
> pcm_mutex is applied always on either the top PCM callbacks or the
> external call from DAPM, not taken in the internal functions.
> 
> 2) the FE stream lock is taken in higher levels before invoking
> dpcm_be_dai_trigger()
> 
> 3) when adding and deleting a BE, both the pcm_mutex and FE stream
> lock are taken.
> 
> Signed-off-by: Takashi Iwai <tiwai@...e.de>
> [clarification of commit message by plbossart]
> Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart@...ux.intel.com>
> Reviewed-by: Kai Vehmanen <kai.vehmanen@...ux.intel.com>
> Reviewed-by: Bard Liao <yung-chuan.liao@...ux.intel.com>
> Reviewed-by: Ranjani Sridharan <ranjani.sridharan@...ux.intel.com>
> Link: https://lore.kernel.org/r/20211207173745.15850-4-pierre-louis.bossart@linux.intel.com
> Cc: stable@...r.kernel.org # 5.15.x
> Signed-off-by: Mark Brown <broonie@...nel.org>
> ---
>  include/sound/soc.h  |   2 -
>  sound/soc/soc-core.c |   1 -
>  sound/soc/soc-pcm.c  | 229 ++++++++++++++++++++++++++++---------------
>  3 files changed, 152 insertions(+), 80 deletions(-)

<formletter>

This is not the correct way to submit patches for inclusion in the
stable kernel tree.  Please read:
    https://www.kernel.org/doc/html/latest/process/stable-kernel-rules.html
for how to do this properly.

</formletter>