commit 34f3c89fda4fba9fe689db22253ca8db2f5e6386
author Takashi Iwai <tiwai@suse.de> Mon Oct 15 12:16:02 2012 +0200
committer Takashi Iwai <tiwai@suse.de> Tue Oct 30 11:07:00 2012 +0100
tree 213e1b6e6ceaee42dc4f9ec74307794dc7a83b20
parent 978520b75f0a1ce82b17e1e8186417250de6d545

ALSA: usb-audio: Use rwsem for disconnect protection

Replace mutex with rwsem for codec->shutdown protection so that
concurrent accesses are allowed.

Also add the protection to snd_usb_autosuspend() and
snd_usb_autoresume(), too.

Reported-by: Matthieu CASTET <matthieu.castet@parrot.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Takashi Iwai <tiwai@suse.de>

sound/usb/pcm.c

diff --git a/sound/usb/pcm.c b/sound/usb/pcm.c
index 55e741c..37428f7 100644
--- a/sound/usb/pcm.c
+++ b/sound/usb/pcm.c
@@ -503,12 +503,12 @@
 		return -EINVAL;
 	}
 
-	mutex_lock(&subs->stream->chip->shutdown_mutex);
+	down_read(&subs->stream->chip->shutdown_rwsem);
 	if (subs->stream->chip->shutdown)
 		ret = -ENODEV;
 	else
 		ret = set_format(subs, fmt);
-	mutex_unlock(&subs->stream->chip->shutdown_mutex);
+	up_read(&subs->stream->chip->shutdown_rwsem);
 	if (ret < 0)
 		return ret;
 
@@ -531,12 +531,12 @@
 	subs->cur_audiofmt = NULL;
 	subs->cur_rate = 0;
 	subs->period_bytes = 0;
-	mutex_lock(&subs->stream->chip->shutdown_mutex);
+	down_read(&subs->stream->chip->shutdown_rwsem);
 	if (!subs->stream->chip->shutdown) {
 		stop_endpoints(subs, 0, 1, 1);
 		deactivate_endpoints(subs);
 	}
-	mutex_unlock(&subs->stream->chip->shutdown_mutex);
+	up_read(&subs->stream->chip->shutdown_rwsem);
 	return snd_pcm_lib_free_vmalloc_buffer(substream);
 }
 
@@ -558,7 +558,7 @@
 		return -ENXIO;
 	}
 
-	mutex_lock(&subs->stream->chip->shutdown_mutex);
+	down_read(&subs->stream->chip->shutdown_rwsem);
 	if (subs->stream->chip->shutdown) {
 		ret = -ENODEV;
 		goto unlock;
@@ -608,7 +608,7 @@
 		ret = start_endpoints(subs, 1);
 
  unlock:
-	mutex_unlock(&subs->stream->chip->shutdown_mutex);
+	up_read(&subs->stream->chip->shutdown_rwsem);
 	return ret;
 }