From: "Geoffrey D. Bennett" g@b4.vu

[ Upstream commit 9b5ddea9ce5a68d7d2bedcb69901ac2a86c96c7b ]

The private->vol_updated flag was being checked outside of the mutex_lock/unlock() of private->data_mutex leading to the volume data being fetched twice from the device unnecessarily or old volume data being returned.

Update scarlett2_*_ctl_get() and include the private->vol_updated flag check inside the critical region.

Signed-off-by: Geoffrey D. Bennett g@b4.vu Link: https://lore.kernel.org/r/20210620164643.GA9216@m.b4.vu Signed-off-by: Takashi Iwai tiwai@suse.de Signed-off-by: Sasha Levin sashal@kernel.org --- sound/usb/mixer_scarlett_gen2.c | 21 +++++++++------------ 1 file changed, 9 insertions(+), 12 deletions(-)

diff --git a/sound/usb/mixer_scarlett_gen2.c b/sound/usb/mixer_scarlett_gen2.c index e605ec5a91ba..38b3a0352b24 100644 --- a/sound/usb/mixer_scarlett_gen2.c +++ b/sound/usb/mixer_scarlett_gen2.c @@ -1028,11 +1028,10 @@ static int scarlett2_master_volume_ctl_get(struct snd_kcontrol *kctl, struct usb_mixer_interface *mixer = elem->head.mixer; struct scarlett2_mixer_data *private = mixer->private_data;

- if (private->vol_updated) { - mutex_lock(&private->data_mutex); + mutex_lock(&private->data_mutex); + if (private->vol_updated) scarlett2_update_volumes(mixer); - mutex_unlock(&private->data_mutex); - } + mutex_unlock(&private->data_mutex);

ucontrol->value.integer.value[0] = private->master_vol; return 0; @@ -1046,11 +1045,10 @@ static int scarlett2_volume_ctl_get(struct snd_kcontrol *kctl, struct scarlett2_mixer_data *private = mixer->private_data; int index = elem->control;

- if (private->vol_updated) { - mutex_lock(&private->data_mutex); + mutex_lock(&private->data_mutex); + if (private->vol_updated) scarlett2_update_volumes(mixer); - mutex_unlock(&private->data_mutex); - } + mutex_unlock(&private->data_mutex);

ucontrol->value.integer.value[0] = private->vol[index]; return 0; @@ -1314,11 +1312,10 @@ static int scarlett2_button_ctl_get(struct snd_kcontrol *kctl, struct usb_mixer_interface *mixer = elem->head.mixer; struct scarlett2_mixer_data *private = mixer->private_data;

- if (private->vol_updated) { - mutex_lock(&private->data_mutex); + mutex_lock(&private->data_mutex); + if (private->vol_updated) scarlett2_update_volumes(mixer); - mutex_unlock(&private->data_mutex); - } + mutex_unlock(&private->data_mutex);

ucontrol->value.enumerated.item[0] = private->buttons[elem->control]; return 0;