[ALSA] Fix hang-up at disconnection of usb-audio

Fix hang-up at disconnection of usb-audio devices while accessing PCM.
Don't handle PCM operations any more after shutdown flag is set.
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Jaroslav Kysela <perex@suse.cz>

sound/core/oss/pcm_oss.c

@@ -2359,7 +2359,8 @@ static int snd_pcm_oss_release(struct inode *inode, struct file *file)
 		substream = pcm_oss_file->streams[SNDRV_PCM_STREAM_CAPTURE];
 	snd_assert(substream != NULL, return -ENXIO);
 	pcm = substream->pcm;
-	snd_pcm_oss_sync(pcm_oss_file);
+	if (!pcm->card->shutdown)
+		snd_pcm_oss_sync(pcm_oss_file);
 	mutex_lock(&pcm->open_mutex);
 	snd_pcm_oss_release_file(pcm_oss_file);
 	mutex_unlock(&pcm->open_mutex);

sound/core/pcm_native.c

@@ -1310,7 +1310,8 @@ static int snd_pcm_pre_prepare(struct snd_pcm_substream *substream,
 			       int f_flags)
 {
 	struct snd_pcm_runtime *runtime = substream->runtime;
-	if (runtime->status->state == SNDRV_PCM_STATE_OPEN)
+	if (runtime->status->state == SNDRV_PCM_STATE_OPEN ||
+	    runtime->status->state == SNDRV_PCM_STATE_DISCONNECTED)
 		return -EBADFD;
 	if (snd_pcm_running(substream))
 		return -EBUSY;
@@ -1568,7 +1569,8 @@ static int snd_pcm_drop(struct snd_pcm_substream *substream)
 	runtime = substream->runtime;
 	card = substream->pcm->card;
 
-	if (runtime->status->state == SNDRV_PCM_STATE_OPEN)
+	if (runtime->status->state == SNDRV_PCM_STATE_OPEN ||
+	    runtime->status->state == SNDRV_PCM_STATE_DISCONNECTED)
 		return -EBADFD;
 
 	snd_power_lock(card);

sound/usb/usbaudio.c

@@ -1469,7 +1469,8 @@ static int snd_usb_hw_free(struct snd_pcm_substream *substream)
 	subs->cur_audiofmt = NULL;
 	subs->cur_rate = 0;
 	subs->period_bytes = 0;
-	release_substream_urbs(subs, 0);
+	if (!subs->stream->chip->shutdown)
+		release_substream_urbs(subs, 0);
 	return snd_pcm_free_vmalloc_buffer(substream);
 }