linux-kernel - Re: [PATCH] ASoC: soc-compress: Fix deadlock in soc_compr_open

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Date:   Thu, 15 Jun 2023 01:56:35 +0100
From:   Mark Brown <broonie@...nel.org>
To:     yixuanjiang <yixuanjiang@...gle.com>
Cc:     vkoul@...nel.org, lgirdwood@...il.com, perex@...ex.cz,
        tiwai@...e.com, alsa-devel@...a-project.org,
        linux-kernel@...r.kernel.org, stable@...r.kernel.org
Subject: Re: [PATCH] ASoC: soc-compress: Fix deadlock in soc_compr_open_fe

On Tue, Jun 13, 2023 at 02:23:50PM +0800, yixuanjiang wrote:
> Modify the error handling flow by release lock.
> The require pcm_mutex will keep holding if open fail.

> +++ b/sound/soc/soc-compress.c
> @@ -166,6 +166,7 @@ static int soc_compr_open_fe(struct snd_compr_stream *cstream)
>  	snd_soc_dai_compr_shutdown(cpu_dai, cstream, 1);
>  out:
>  	dpcm_path_put(&list);
> +	mutex_unlock(&fe->card->pcm_mutex);
>  be_err:

This is really hard to follow due to the lack of any mutex_lock()s in
the function, I think because this is intended to undo
snd_soc_dpcm_mutex_lock(fe) but if that's the case why is it not using
snd_soc_dpcm_mutex_unlock(fe) like the success path does?  Given the use
of classes not doing that looks like it'll create lockdep issues.

I'd expect the unlock to match the lock.

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