linux-kernel - Re: [PATCH] ASoC: soc-pcm: use GFP_ATOMIC in dpcm_create_debugfs

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Date:   Mon, 17 Jan 2022 09:49:46 +0100
From:   Takashi Iwai <tiwai@...e.de>
To:     Christophe JAILLET <christophe.jaillet@...adoo.fr>
Cc:     Liam Girdwood <lgirdwood@...il.com>,
        Mark Brown <broonie@...nel.org>,
        Jaroslav Kysela <perex@...ex.cz>,
        Takashi Iwai <tiwai@...e.com>,
        Bard Liao <yung-chuan.liao@...ux.intel.com>,
        Ranjani Sridharan <ranjani.sridharan@...ux.intel.com>,
        Kai Vehmanen <kai.vehmanen@...ux.intel.com>,
        Pierre-Louis Bossart <pierre-louis.bossart@...ux.intel.com>,
        linux-kernel@...r.kernel.org, kernel-janitors@...r.kernel.org,
        alsa-devel@...a-project.org
Subject: Re: [PATCH] ASoC: soc-pcm: use GFP_ATOMIC in dpcm_create_debugfs_state()

On Sun, 16 Jan 2022 12:18:17 +0100,
Christophe JAILLET wrote:
> 
> The commit below states that dpcm_be_connect() may be called from atomic
> context. It changes a GFP_KERNEL into a GFP_ATOMIC to deal with it.
> 
> Another memory allocation is done in dpcm_create_debugfs_state() which is
> called by dpcm_be_connect(). Also use GFP_ATOMIC there to be consistent
> and be compliant with atomic context.
> 
> Fixes: d8a9c6e1f676 ("ASoC: soc-pcm: use GFP_ATOMIC for dpcm structure")
> Signed-off-by: Christophe JAILLET <christophe.jaillet@...adoo.fr>
> ---
> Not clear to me how dpcm_be_connect() can be called from an atomic context,
> though. But better safe than sorry.

I don't think this no longer valid for the very latest code.
The commit b7898396f4bb dropped the spurious dpcm_lock spinlock, so
the code path you touched must be always sleepable.

Similarly, the commit d8a9c6e1f676 can be reverted now.


thanks,

Takashi

> ---
>  sound/soc/soc-pcm.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/sound/soc/soc-pcm.c b/sound/soc/soc-pcm.c
> index 7abfc48b26ca..1a536a2b9dc3 100644
> --- a/sound/soc/soc-pcm.c
> +++ b/sound/soc/soc-pcm.c
> @@ -212,7 +212,7 @@ static void dpcm_create_debugfs_state(struct snd_soc_dpcm *dpcm, int stream)
>  {
>  	char *name;
>  
> -	name = kasprintf(GFP_KERNEL, "%s:%s", dpcm->be->dai_link->name,
> +	name = kasprintf(GFP_ATOMIC, "%s:%s", dpcm->be->dai_link->name,
>  			 stream ? "capture" : "playback");
>  	if (name) {
>  		dpcm->debugfs_state = debugfs_create_dir(
> -- 
> 2.32.0
>