Commit 9b5ddea9 authored by Geoffrey D. Bennett's avatar Geoffrey D. Bennett Committed by Takashi Iwai
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ALSA: usb-audio: scarlett2: Fix data_mutex lock 



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: default avatarGeoffrey D. Bennett <g@b4.vu>
Link: https://lore.kernel.org/r/20210620164643.GA9216@m.b4.vu


Signed-off-by: default avatarTakashi Iwai <tiwai@suse.de>
parent 3eeb2a19

sound/usb/mixer_scarlett_gen2.c

+9 −12
Original line number Diff line number Diff line
@@ -1153,11 +1153,10 @@ static int scarlett2_master_volume_ctl_get(struct snd_kcontrol *kctl, 
	struct usb_mixer_interface *mixer = elem->head.mixer;

	struct scarlett2_data *private = mixer->private_data;



	if (private->vol_updated) {

	mutex_lock(&private->data_mutex);

	if (private->vol_updated)

		scarlett2_update_volumes(mixer);

	mutex_unlock(&private->data_mutex);

	}



	ucontrol->value.integer.value[0] = private->master_vol;

	return 0;
@@ -1171,11 +1170,10 @@ static int scarlett2_volume_ctl_get(struct snd_kcontrol *kctl, 
	struct scarlett2_data *private = mixer->private_data;

	int index = elem->control;



	if (private->vol_updated) {

	mutex_lock(&private->data_mutex);

	if (private->vol_updated)

		scarlett2_update_volumes(mixer);

	mutex_unlock(&private->data_mutex);

	}



	ucontrol->value.integer.value[0] = private->vol[index];

	return 0;
@@ -1439,11 +1437,10 @@ static int scarlett2_dim_mute_ctl_get(struct snd_kcontrol *kctl, 
	struct usb_mixer_interface *mixer = elem->head.mixer;

	struct scarlett2_data *private = mixer->private_data;



	if (private->vol_updated) {

	mutex_lock(&private->data_mutex);

	if (private->vol_updated)

		scarlett2_update_volumes(mixer);

	mutex_unlock(&private->data_mutex);

	}



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

	return 0;