ALSA: PCM: Fix some races at disconnection

commit 9b0573c07f278e9888c352aa9724035c75784ea0 upstream.

Fix races at PCM disconnection:
- while a PCM device is being opened or closed
- while the PCM state is being changed without lock in prepare,
  hw_params, hw_free ops

Reported-by: Matthieu CASTET <matthieu.castet@parrot.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 6 insertions, 1 deletions

diff --git a/sound/core/pcm.c b/sound/core/pcm.c
index 1a3070b4e5b5..099f3fdd120a 100644
--- a/sound/core/pcm.c
+++ b/sound/core/pcm.c
@@ -1086,11 +1086,15 @@ static int snd_pcm_dev_disconnect(struct snd_device *device)
 	if (list_empty(&pcm->list))
 		goto unlock;
 
+	mutex_lock(&pcm->open_mutex);
 	list_del_init(&pcm->list);
 	for (cidx = 0; cidx < 2; cidx++)
-		for (substream = pcm->streams[cidx].substream; substream; substream = substream->next)
+		for (substream = pcm->streams[cidx].substream; substream; substream = substream->next) {
+			snd_pcm_stream_lock_irq(substream);
 			if (substream->runtime)
 				substream->runtime->status->state = SNDRV_PCM_STATE_DISCONNECTED;
+			snd_pcm_stream_unlock_irq(substream);
+		}
 	list_for_each_entry(notify, &snd_pcm_notify_list, list) {
 		notify->n_disconnect(pcm);
 	}
@@ -1106,6 +1110,7 @@ static int snd_pcm_dev_disconnect(struct snd_device *device)
 		}
 		snd_unregister_device(devtype, pcm->card, pcm->device);
 	}
+	mutex_unlock(&pcm->open_mutex);
  unlock:
 	mutex_unlock(&register_mutex);
 	return 0;