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>

1 files changed, 8 insertions, 4 deletions

diff --git a/sound/usb/card.c b/sound/usb/card.c
index 561bb74fd364..282f0fc9fed1 100644
--- a/sound/usb/card.c
+++ b/sound/usb/card.c
@@ -339,7 +339,7 @@ static int snd_usb_audio_create(struct usb_device *dev, int idx,
         }
 
         mutex_init(&chip->mutex);
-        mutex_init(&chip->shutdown_mutex);
+        init_rwsem(&chip->shutdown_rwsem);
         chip->index = idx;
         chip->dev = dev;
         chip->card = card;
@@ -560,7 +560,7 @@ static void snd_usb_audio_disconnect(struct usb_device *dev,
 
         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) {
@@ -582,11 +582,11 @@ static void snd_usb_audio_disconnect(struct usb_device *dev,
                         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);
         }
 }
@@ -618,16 +618,20 @@ int snd_usb_autoresume(struct snd_usb_audio *chip)
 {
         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)