ALSA: usb-audio: Use rwsem for disconnect protection
Takashi Iwai [Wed, 7 Nov 2012 11:42:45 +0000 (12:42 +0100)]
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
sound/usb/mixer.c
sound/usb/pcm.c
sound/usb/usbaudio.h

index 4a7be7b..147a5c4 100644 (file)
@@ -336,7 +336,7 @@ static int snd_usb_audio_create(struct usb_device *dev, int idx,
                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 @@ 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) {
@@ -574,11 +574,11 @@ 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);
        }
 }
@@ -610,16 +610,20 @@ 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)
index b3b63f7..29ae209 100644 (file)
@@ -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;
 }
index 4f49ca7..4a99f6c 100644 (file)
@@ -376,7 +376,7 @@ static int snd_usb_hw_params(struct snd_pcm_substream *substream,
                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 @@ static int snd_usb_hw_params(struct snd_pcm_substream *substream,
        }
 
 unlock:
-       mutex_unlock(&subs->stream->chip->shutdown_mutex);
+       up_read(&subs->stream->chip->shutdown_rwsem);
        return ret;
 }
 
@@ -422,9 +422,9 @@ 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);
        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 @@ 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;
@@ -463,7 +463,7 @@ static int snd_usb_pcm_prepare(struct snd_pcm_substream *substream)
 
        ret = snd_usb_substream_prepare(subs, runtime);
  unlock:
-       mutex_unlock(&subs->stream->chip->shutdown_mutex);
+       up_read(&subs->stream->chip->shutdown_rwsem);
        return ret;
 }
 
index 3e2b035..6c805a5 100644 (file)
@@ -36,7 +36,7 @@ struct snd_usb_audio {
        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;