commit 49e44e317fdb73d75a00a058df75a6b6fe172c08
author Takashi Iwai <tiwai@suse.de> Wed Nov 07 12:42:45 2012 +0100
committer Greg Kroah-Hartman <gregkh@linuxfoundation.org> Sat Nov 17 13:16:12 2012 -0800
tree abeaf4b344a9f59e76fce60b7d129d7fa6a36582
parent 799c92f2aecb348e4a4c6dab80c7206e48caf201

ALSA: usb-audio: Use rwsem for disconnect protection

commit 34f3c89fda4fba9fe689db22253ca8db2f5e6386 upstream.

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>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

sound/usb/card.c

diff --git a/sound/usb/card.c b/sound/usb/card.c
index 4a7be7b..147a5c4 100644
--- a/sound/usb/card.c
+++ b/sound/usb/card.c
@@ -336,7 +336,7 @@
 		return -ENOMEM;
 	}
 
-	mutex_init(&chip->shutdown_mutex);
+	init_rwsem(&chip->shutdown_rwsem);
 	chip->index = idx;
 	chip->dev = dev;
 	chip->card = card;
@@ -556,7 +556,7 @@
 
 	card = chip->card;
 	mutex_lock(&register_mutex);
-	mutex_lock(&chip->shutdown_mutex);
+	down_write(&chip->shutdown_rwsem);
 	chip->shutdown = 1;
 	chip->num_interfaces--;
 	if (chip->num_interfaces <= 0) {
@@ -574,11 +574,11 @@
 			snd_usb_mixer_disconnect(p);
 		}
 		usb_chip[chip->index] = NULL;
-		mutex_unlock(&chip->shutdown_mutex);
+		up_write(&chip->shutdown_rwsem);
 		mutex_unlock(&register_mutex);
 		snd_card_free_when_closed(card);
 	} else {
-		mutex_unlock(&chip->shutdown_mutex);
+		up_write(&chip->shutdown_rwsem);
 		mutex_unlock(&register_mutex);
 	}
 }
@@ -610,16 +610,20 @@
 {
 	int err = -ENODEV;
 
+	down_read(&chip->shutdown_rwsem);
 	if (!chip->shutdown && !chip->probing)
 		err = usb_autopm_get_interface(chip->pm_intf);
+	up_read(&chip->shutdown_rwsem);
 
 	return err;
 }
 
 void snd_usb_autosuspend(struct snd_usb_audio *chip)
 {
+	down_read(&chip->shutdown_rwsem);
 	if (!chip->shutdown && !chip->probing)
 		usb_autopm_put_interface(chip->pm_intf);
+	up_read(&chip->shutdown_rwsem);
 }
 
 static int usb_audio_suspend(struct usb_interface *intf, pm_message_t message)

sound/usb/mixer.c

diff --git a/sound/usb/mixer.c b/sound/usb/mixer.c
index b3b63f7..29ae209 100644
--- a/sound/usb/mixer.c
+++ b/sound/usb/mixer.c
@@ -292,7 +292,7 @@
 	err = snd_usb_autoresume(cval->mixer->chip);
 	if (err < 0)
 		return -EIO;
-	mutex_lock(&chip->shutdown_mutex);
+	down_read(&chip->shutdown_rwsem);
 	while (timeout-- > 0) {
 		if (chip->shutdown)
 			break;
@@ -310,7 +310,7 @@
 	err = -EINVAL;
 
  out:
-	mutex_unlock(&chip->shutdown_mutex);
+	up_read(&chip->shutdown_rwsem);
 	snd_usb_autosuspend(cval->mixer->chip);
 	return err;
 }
@@ -337,7 +337,7 @@
 	if (ret)
 		goto error;
 
-	mutex_lock(&chip->shutdown_mutex);
+	down_read(&chip->shutdown_rwsem);
 	if (chip->shutdown)
 		ret = -ENODEV;
 	else {
@@ -346,7 +346,7 @@
 			      USB_RECIP_INTERFACE | USB_TYPE_CLASS | USB_DIR_IN,
 			      validx, idx, buf, size);
 	}
-	mutex_unlock(&chip->shutdown_mutex);
+	up_read(&chip->shutdown_rwsem);
 	snd_usb_autosuspend(chip);
 
 	if (ret < 0) {
@@ -453,7 +453,7 @@
 	err = snd_usb_autoresume(chip);
 	if (err < 0)
 		return -EIO;
-	mutex_lock(&chip->shutdown_mutex);
+	down_read(&chip->shutdown_rwsem);
 	while (timeout-- > 0) {
 		if (chip->shutdown)
 			break;
@@ -471,7 +471,7 @@
 	err = -EINVAL;
 
  out:
-	mutex_unlock(&chip->shutdown_mutex);
+	up_read(&chip->shutdown_rwsem);
 	snd_usb_autosuspend(chip);
 	return err;
 }

sound/usb/pcm.c

diff --git a/sound/usb/pcm.c b/sound/usb/pcm.c
index 4f49ca7..4a99f6c 100644
--- a/sound/usb/pcm.c
+++ b/sound/usb/pcm.c
@@ -376,7 +376,7 @@
 		subs->period_bytes != params_period_bytes(hw_params) ||
 		subs->cur_rate != rate;
 
-	mutex_lock(&subs->stream->chip->shutdown_mutex);
+	down_read(&subs->stream->chip->shutdown_rwsem);
 	if (subs->stream->chip->shutdown) {
 		ret = -ENODEV;
 		goto unlock;
@@ -406,7 +406,7 @@
 	}
 
 unlock:
-	mutex_unlock(&subs->stream->chip->shutdown_mutex);
+	up_read(&subs->stream->chip->shutdown_rwsem);
 	return ret;
 }
 
@@ -422,9 +422,9 @@
 	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);
 	snd_usb_release_substream_urbs(subs, 0);
-	mutex_unlock(&subs->stream->chip->shutdown_mutex);
+	up_read(&subs->stream->chip->shutdown_rwsem);
 	return snd_pcm_lib_free_vmalloc_buffer(substream);
 }
 
@@ -444,7 +444,7 @@
 		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;
@@ -463,7 +463,7 @@
 
 	ret = snd_usb_substream_prepare(subs, runtime);
  unlock:
-	mutex_unlock(&subs->stream->chip->shutdown_mutex);
+	up_read(&subs->stream->chip->shutdown_rwsem);
 	return ret;
 }
 

sound/usb/usbaudio.h

diff --git a/sound/usb/usbaudio.h b/sound/usb/usbaudio.h
index 3e2b035..6c805a5 100644
--- a/sound/usb/usbaudio.h
+++ b/sound/usb/usbaudio.h
@@ -36,7 +36,7 @@
 	struct snd_card *card;
 	struct usb_interface *pm_intf;
 	u32 usb_id;
-	struct mutex shutdown_mutex;
+	struct rw_semaphore shutdown_rwsem;
 	unsigned int shutdown:1;
 	unsigned int probing:1;
 	unsigned int autosuspended:1;