ALSA: pcm: Don't call sync_stop if it hasn't been stopped

The PCM stop operation sets the stop_operating flag for indicating the
sync_stop post-process.  This flag is, however, set unconditionally
even if the PCM trigger weren't issued.  This may lead to
inconsistency in the driver side.

Correct the code to set stop_operating flag only after the trigger
STOP is actually called.

Fixes: 1e850bee ("ALSA: pcm: Add the support for sync-stop operation")
Cc: <stable@vger.kernel.org>
Link: https://lore.kernel.org/r/20210206203656.15959-4-tiwai@suse.deSigned-off-by: Takashi Iwai <tiwai@suse.de>

sound/core/pcm_native.c

@@ -1421,8 +1421,10 @@ static int snd_pcm_do_stop(struct snd_pcm_substream *substream,
 			   snd_pcm_state_t state)
 {
 	if (substream->runtime->trigger_master == substream &&
-	    snd_pcm_running(substream))
+	    snd_pcm_running(substream)) {
 		substream->ops->trigger(substream, SNDRV_PCM_TRIGGER_STOP);
+		substream->runtime->stop_operating = true;
+	}
 	return 0; /* unconditonally stop all substreams */
 }
 
@@ -1435,7 +1437,6 @@ static void snd_pcm_post_stop(struct snd_pcm_substream *substream,
 		runtime->status->state = state;
 		snd_pcm_timer_notify(substream, SNDRV_TIMER_EVENT_MSTOP);
 	}
-	runtime->stop_operating = true;
 	wake_up(&runtime->sleep);
 	wake_up(&runtime->tsleep);
 }