[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>

1 files changed, 2 insertions, 1 deletions

diff --git a/sound/usb/usbaudio.c b/sound/usb/usbaudio.c
index c82b01c7ad3a..67202b9eeb77 100644
--- a/sound/usb/usbaudio.c
+++ b/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);
 }