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: Jaroslav Kysela <perex@perex.cz>
Link: https://lore.kernel.org/r/20220322171325.4355-1-tiwai@suse.de
Signed-off-by: Takashi Iwai <tiwai@suse.de>

diff --git a/sound/core/pcm_native.c b/sound/core/pcm_native.c
index 0e4fbf5..704fdc9 100644 (file)
--- a/sound/core/pcm_native.c
+++ b/sound/core/pcm_native.c
@@ -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 = {