ALSA: Get rid of card power_lock

Currently we're taking power_lock at each card component for assuring
the power-up sequence, but it doesn't help anything in the
implementation at the moment: it just serializes unnecessarily the
callers, but it doesn't protect about the power state change itself.
It used to have some usefulness in the early days where we managed the
PM manually.  But now the suspend/resume core procedure is beyond our
hands, and power_lock lost its meaning.

This patch drops the power_lock from allover the places.
There shouldn't be any issues by this change, as it's no helper
regarding the power state change.  Rather we'll get better performance
by removing the serialization; which is the only slight concern of any
behavior change, but it can't be a showstopper, after all.

Signed-off-by: Takashi Iwai <tiwai@suse.de>

1 files changed, 31 insertions, 27 deletions

diff --git a/sound/core/control.c b/sound/core/control.c
index 51d4b4ad3e1d..56b3e2d49c82 100644
--- a/sound/core/control.c
+++ b/sound/core/control.c
@@ -864,14 +864,14 @@ static int snd_ctl_elem_info_user(struct snd_ctl_file *ctl,
 
 	if (copy_from_user(&info, _info, sizeof(info)))
 		return -EFAULT;
-	snd_power_lock(ctl->card);
 	result = snd_power_wait(ctl->card, SNDRV_CTL_POWER_D0);
-	if (result >= 0)
-		result = snd_ctl_elem_info(ctl, &info);
-	snd_power_unlock(ctl->card);
-	if (result >= 0)
-		if (copy_to_user(_info, &info, sizeof(info)))
-			return -EFAULT;
+	if (result < 0)
+		return result;
+	result = snd_ctl_elem_info(ctl, &info);
+	if (result < 0)
+		return result;
+	if (copy_to_user(_info, &info, sizeof(info)))
+		return -EFAULT;
 	return result;
 }
 
@@ -905,17 +905,19 @@ static int snd_ctl_elem_read_user(struct snd_card *card,
 	if (IS_ERR(control))
 		return PTR_ERR(control);
 
-	snd_power_lock(card);
 	result = snd_power_wait(card, SNDRV_CTL_POWER_D0);
-	if (result >= 0) {
-		down_read(&card->controls_rwsem);
-		result = snd_ctl_elem_read(card, control);
-		up_read(&card->controls_rwsem);
-	}
-	snd_power_unlock(card);
-	if (result >= 0)
-		if (copy_to_user(_control, control, sizeof(*control)))
-			result = -EFAULT;
+	if (result < 0)
+		goto error;
+
+	down_read(&card->controls_rwsem);
+	result = snd_ctl_elem_read(card, control);
+	up_read(&card->controls_rwsem);
+	if (result < 0)
+		goto error;
+
+	if (copy_to_user(_control, control, sizeof(*control)))
+		result = -EFAULT;
+ error:
 	kfree(control);
 	return result;
 }
@@ -964,17 +966,19 @@ static int snd_ctl_elem_write_user(struct snd_ctl_file *file,
 		return PTR_ERR(control);
 
 	card = file->card;
-	snd_power_lock(card);
 	result = snd_power_wait(card, SNDRV_CTL_POWER_D0);
-	if (result >= 0) {
-		down_write(&card->controls_rwsem);
-		result = snd_ctl_elem_write(card, file, control);
-		up_write(&card->controls_rwsem);
-	}
-	snd_power_unlock(card);
-	if (result >= 0)
-		if (copy_to_user(_control, control, sizeof(*control)))
-			result = -EFAULT;
+	if (result < 0)
+		goto error;
+
+	down_write(&card->controls_rwsem);
+	result = snd_ctl_elem_write(card, file, control);
+	up_write(&card->controls_rwsem);
+	if (result < 0)
+		goto error;
+
+	if (copy_to_user(_control, control, sizeof(*control)))
+		result = -EFAULT;
+ error:
 	kfree(control);
 	return result;
 }