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, 6 insertions, 6 deletions

diff --git a/sound/usb/mixer.c b/sound/usb/mixer.c
index c2ef11ccd66a..298070e8f2d4 100644
--- a/sound/usb/mixer.c
+++ b/sound/usb/mixer.c
@@ -292,7 +292,7 @@ static int get_ctl_value_v1(struct usb_mixer_elem_info *cval, int request, int v
         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 @@ static int get_ctl_value_v1(struct usb_mixer_elem_info *cval, int request, int v
         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 @@ static int get_ctl_value_v2(struct usb_mixer_elem_info *cval, int request, int v
         if (ret)
                 goto error;
 
-        mutex_lock(&chip->shutdown_mutex);
+        down_read(&chip->shutdown_rwsem);
         if (chip->shutdown)
                 ret = -ENODEV;
         else {
@@ -346,7 +346,7 @@ static int get_ctl_value_v2(struct usb_mixer_elem_info *cval, int request, int v
                               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 @@ int snd_usb_mixer_set_ctl_value(struct usb_mixer_elem_info *cval,
         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 @@ int snd_usb_mixer_set_ctl_value(struct usb_mixer_elem_info *cval,
         err = -EINVAL;
 
  out:
-        mutex_unlock(&chip->shutdown_mutex);
+        up_read(&chip->shutdown_rwsem);
         snd_usb_autosuspend(chip);
         return err;
 }