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    Subject[PATCH 5.10 23/38] ALSA: pcm: Add stream lock during PCM reset ioctl operations
    Date
    From: Takashi Iwai <tiwai@suse.de>

    commit 1f68915b2efd0d6bfd6e124aa63c94b3c69f127c upstream.

    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>
    Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
    ---
    sound/core/pcm_native.c | 4 ++++
    1 file changed, 4 insertions(+)

    --- a/sound/core/pcm_native.c
    +++ b/sound/core/pcm_native.c
    @@ -1850,11 +1850,13 @@ static int snd_pcm_do_reset(struct snd_p
    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;
    }

    @@ -1862,10 +1864,12 @@ static void snd_pcm_post_reset(struct sn
    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 = {

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