[ 33/57] ALSA: usb-audio: Use rwsem for disconnect protection

From: Greg Kroah-Hartman
Date: Wed Nov 14 2012 - 23:19:41 EST


3.4-stable review patch. If anyone has any objections, please let me know.

------------------

From: Takashi Iwai <tiwai@xxxxxxx>

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@xxxxxxxxxx>
Signed-off-by: Takashi Iwai <tiwai@xxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
sound/usb/card.c | 12 ++++++++----
sound/usb/mixer.c | 12 ++++++------
sound/usb/pcm.c | 12 ++++++------
sound/usb/usbaudio.h | 2 +-
4 files changed, 21 insertions(+), 17 deletions(-)

--- a/sound/usb/card.c
+++ b/sound/usb/card.c
@@ -336,7 +336,7 @@ static int snd_usb_audio_create(struct u
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(str

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(str
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_au
{
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)
--- a/sound/usb/mixer.c
+++ b/sound/usb/mixer.c
@@ -292,7 +292,7 @@ static int get_ctl_value_v1(struct usb_m
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_m
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_m
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_m
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 u
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 u
err = -EINVAL;

out:
- mutex_unlock(&chip->shutdown_mutex);
+ up_read(&chip->shutdown_rwsem);
snd_usb_autosuspend(chip);
return err;
}
--- a/sound/usb/pcm.c
+++ b/sound/usb/pcm.c
@@ -376,7 +376,7 @@ static int snd_usb_hw_params(struct snd_
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_
}

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_pc
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 sn
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 sn

ret = snd_usb_substream_prepare(subs, runtime);
unlock:
- mutex_unlock(&subs->stream->chip->shutdown_mutex);
+ up_read(&subs->stream->chip->shutdown_rwsem);
return ret;
}

--- a/sound/usb/usbaudio.h
+++ b/sound/usb/usbaudio.h
@@ -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;


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