Commit 1f68915b authored by Takashi Iwai's avatar Takashi Iwai
Browse files

ALSA: pcm: Add stream lock during PCM reset ioctl operations 



snd_pcm_reset() is a non-atomic operation, and it's allowed to run
during the PCM stream running.  It implies that the manipulation of
hw_ptr and other parameters might be racy.

This patch adds the PCM stream lock at appropriate places in
snd_pcm_*_reset() actions for covering that.

Cc: <stable@vger.kernel.org>
Reviewed-by: default avatarJaroslav Kysela <perex@perex.cz>
Link: https://lore.kernel.org/r/20220322171325.4355-1-tiwai@suse.de


Signed-off-by: default avatarTakashi Iwai <tiwai@suse.de>
parent 69534c48

sound/core/pcm_native.c

+4 −0
Original line number Diff line number Diff line
@@ -1864,11 +1864,13 @@ static int snd_pcm_do_reset(struct snd_pcm_substream *substream, 
	int err = snd_pcm_ops_ioctl(substream, SNDRV_PCM_IOCTL1_RESET, NULL);

	if (err < 0)

		return err;

	snd_pcm_stream_lock_irq(substream);

	runtime->hw_ptr_base = 0;

	runtime->hw_ptr_interrupt = runtime->status->hw_ptr -

		runtime->status->hw_ptr % runtime->period_size;

	runtime->silence_start = runtime->status->hw_ptr;

	runtime->silence_filled = 0;

	snd_pcm_stream_unlock_irq(substream);

	return 0;

}
@@ -1876,10 +1878,12 @@ static void snd_pcm_post_reset(struct snd_pcm_substream *substream, 
			       snd_pcm_state_t state)

{

	struct snd_pcm_runtime *runtime = substream->runtime;

	snd_pcm_stream_lock_irq(substream);

	runtime->control->appl_ptr = runtime->status->hw_ptr;

	if (substream->stream == SNDRV_PCM_STREAM_PLAYBACK &&

	    runtime->silence_size > 0)

		snd_pcm_playback_silence(substream, ULONG_MAX);

	snd_pcm_stream_unlock_irq(substream);

}



static const struct action_ops snd_pcm_action_reset = {