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>

4 files changed, 21 insertions, 17 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)
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;
 }
diff --git a/sound/usb/pcm.c b/sound/usb/pcm.c
index 55e741c5f231..37428f74dbb6 100644
--- a/sound/usb/pcm.c
+++ b/sound/usb/pcm.c
@@ -503,12 +503,12 @@ static int snd_usb_hw_params(struct snd_pcm_substream *substream,
                 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 @@ static int snd_usb_hw_free(struct snd_pcm_substream *substream)
         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 @@ static int snd_usb_pcm_prepare(struct snd_pcm_substream *substream)
                 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 @@ static int snd_usb_pcm_prepare(struct snd_pcm_substream *substream)
                 ret = start_endpoints(subs, 1);
 
  unlock:
-        mutex_unlock(&subs->stream->chip->shutdown_mutex);
+        up_read(&subs->stream->chip->shutdown_rwsem);
         return ret;
 }
 
diff --git a/sound/usb/usbaudio.h b/sound/usb/usbaudio.h
index b8233ebe250f..ef42797f56fb 100644
--- a/sound/usb/usbaudio.h
+++ b/sound/usb/usbaudio.h
@@ -37,7 +37,7 @@ struct snd_usb_audio {
         struct usb_interface *pm_intf;
         u32 usb_id;
         struct mutex mutex;
-        struct mutex shutdown_mutex;
+        struct rw_semaphore shutdown_rwsem;
         unsigned int shutdown:1;
         unsigned int probing:1;
         unsigned int autosuspended:1;