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>

include/sound/core.h

@@ -136,7 +136,6 @@ struct snd_card {
 
 #ifdef CONFIG_PM
 	unsigned int power_state;	/* power state */
-	struct mutex power_lock;	/* power lock */
 	wait_queue_head_t power_sleep;
 #endif
 
@@ -149,16 +148,6 @@ struct snd_card {
 #define dev_to_snd_card(p)	container_of(p, struct snd_card, card_dev)
 
 #ifdef CONFIG_PM
-static inline void snd_power_lock(struct snd_card *card)
-{
-	mutex_lock(&card->power_lock);
-}
-
-static inline void snd_power_unlock(struct snd_card *card)
-{
-	mutex_unlock(&card->power_lock);
-}
-
 static inline unsigned int snd_power_get_state(struct snd_card *card)
 {
 	return card->power_state;
@@ -175,8 +164,6 @@ int snd_power_wait(struct snd_card *card, unsigned int power_state);
 
 #else /* ! CONFIG_PM */
 
-#define snd_power_lock(card)		do { (void)(card); } while (0)
-#define snd_power_unlock(card)		do { (void)(card); } while (0)
 static inline int snd_power_wait(struct snd_card *card, unsigned int state) { return 0; }
 #define snd_power_get_state(card)	({ (void)(card); SNDRV_CTL_POWER_D0; })
 #define snd_power_change_state(card, state)	do { (void)(card); } while (0)

sound/core/control.c

@@ -864,12 +864,12 @@ 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)
+	if (result < 0)
+		return result;
 	result = snd_ctl_elem_info(ctl, &info);
-	snd_power_unlock(ctl->card);
-	if (result >= 0)
+	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) {
+	if (result < 0)
+		goto error;
+
 	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 (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) {
+	if (result < 0)
+		goto error;
+
 	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 (result < 0)
+		goto error;
+
 	if (copy_to_user(_control, control, sizeof(*control)))
 		result = -EFAULT;
+ error:
 	kfree(control);
 	return result;
 }

sound/core/control_compat.c

@@ -111,12 +111,10 @@ static int snd_ctl_elem_info_compat(struct snd_ctl_file *ctl,
 	if (get_user(data->value.enumerated.item, &data32->value.enumerated.item))
 		goto error;
 
-	snd_power_lock(ctl->card);
 	err = snd_power_wait(ctl->card, SNDRV_CTL_POWER_D0);
-	if (err >= 0)
+	if (err < 0)
+		goto error;
 	err = snd_ctl_elem_info(ctl, data);
-	snd_power_unlock(ctl->card);
-
 	if (err < 0)
 		goto error;
 	/* restore info to 32bit */
@@ -315,14 +313,13 @@ static int ctl_elem_read_user(struct snd_card *card,
 	if (err < 0)
 		goto error;
 
-	snd_power_lock(card);
 	err = snd_power_wait(card, SNDRV_CTL_POWER_D0);
-	if (err >= 0)
+	if (err < 0)
+		goto error;
 	err = snd_ctl_elem_read(card, data);
-	snd_power_unlock(card);
-	if (err >= 0)
-		err = copy_ctl_value_to_user(userdata, valuep, data,
-					     type, count);
+	if (err < 0)
+		goto error;
+	err = copy_ctl_value_to_user(userdata, valuep, data, type, count);
  error:
 	kfree(data);
 	return err;
@@ -344,14 +341,13 @@ static int ctl_elem_write_user(struct snd_ctl_file *file,
 	if (err < 0)
 		goto error;
 
-	snd_power_lock(card);
 	err = snd_power_wait(card, SNDRV_CTL_POWER_D0);
-	if (err >= 0)
+	if (err < 0)
+		goto error;
 	err = snd_ctl_elem_write(card, file, data);
-	snd_power_unlock(card);
-	if (err >= 0)
-		err = copy_ctl_value_to_user(userdata, valuep, data,
-					     type, count);
+	if (err < 0)
+		goto error;
+	err = copy_ctl_value_to_user(userdata, valuep, data, type, count);
  error:
 	kfree(data);
 	return err;

sound/core/init.c

@@ -253,7 +253,6 @@ int snd_card_new(struct device *parent, int idx, const char *xid,
 	spin_lock_init(&card->files_lock);
 	INIT_LIST_HEAD(&card->files_list);
 #ifdef CONFIG_PM
-	mutex_init(&card->power_lock);
 	init_waitqueue_head(&card->power_sleep);
 #endif
 
@@ -978,8 +977,6 @@ EXPORT_SYMBOL(snd_card_file_remove);
  *  Waits until the power-state is changed.
  *
  *  Return: Zero if successful, or a negative error code.
- *
- *  Note: the power lock must be active before call.
  */
 int snd_power_wait(struct snd_card *card, unsigned int power_state)
 {
@@ -999,9 +996,7 @@ int snd_power_wait(struct snd_card *card, unsigned int power_state)
 		if (snd_power_get_state(card) == power_state)
 			break;
 		set_current_state(TASK_UNINTERRUPTIBLE);
-		snd_power_unlock(card);
 		schedule_timeout(30 * HZ);
-		snd_power_lock(card);
 	}
 	remove_wait_queue(&card->power_sleep, &wait);
 	return result;

sound/core/pcm_native.c

@@ -1830,7 +1830,6 @@ static int snd_pcm_drain(struct snd_pcm_substream *substream,
 		add_wait_queue(&to_check->sleep, &wait);
 		snd_pcm_stream_unlock_irq(substream);
 		up_read(&snd_pcm_link_rwsem);
-		snd_power_unlock(card);
 		if (runtime->no_period_wakeup)
 			tout = MAX_SCHEDULE_TIMEOUT;
 		else {
@@ -1842,7 +1841,6 @@ static int snd_pcm_drain(struct snd_pcm_substream *substream,
 			tout = msecs_to_jiffies(tout * 1000);
 		}
 		tout = schedule_timeout_interruptible(tout);
-		snd_power_lock(card);
 		down_read(&snd_pcm_link_rwsem);
 		snd_pcm_stream_lock_irq(substream);
 		remove_wait_queue(&to_check->sleep, &wait);
@@ -2764,11 +2762,16 @@ static int snd_pcm_tstamp(struct snd_pcm_substream *substream, int __user *_arg)
 	return 0;
 }
 		
-static int snd_pcm_common_ioctl(struct file *file,
+static int snd_pcm_common_ioctl1(struct file *file,
 				 struct snd_pcm_substream *substream,
 				 unsigned int cmd, void __user *arg)
 {
 	struct snd_pcm_file *pcm_file = file->private_data;
+	int res;
+
+	res = snd_power_wait(substream->pcm->card, SNDRV_CTL_POWER_D0);
+	if (res < 0)
+		return res;
 
 	switch (cmd) {
 	case SNDRV_PCM_IOCTL_PVERSION:
@@ -2846,21 +2849,6 @@ static int snd_pcm_common_ioctl(struct file *file,
 	return -ENOTTY;
 }
 
-static int snd_pcm_common_ioctl1(struct file *file,
-				 struct snd_pcm_substream *substream,
-				 unsigned int cmd, void __user *arg)
-{
-	struct snd_card *card = substream->pcm->card;
-	int res;
-
-	snd_power_lock(card);
-	res = snd_power_wait(card, SNDRV_CTL_POWER_D0);
-	if (res >= 0)
-		res = snd_pcm_common_ioctl(file, substream, cmd, arg);
-	snd_power_unlock(card);
-	return res;
-}
-
 static int snd_pcm_playback_ioctl1(struct file *file,
 				   struct snd_pcm_substream *substream,
 				   unsigned int cmd, void __user *arg)
@@ -3064,7 +3052,6 @@ int snd_pcm_kernel_ioctl(struct snd_pcm_substream *substream,
 {
 	snd_pcm_uframes_t *frames = arg;
 	snd_pcm_sframes_t result;
-	int err;
 	
 	switch (cmd) {
 	case SNDRV_PCM_IOCTL_FORWARD:
@@ -3084,10 +3071,7 @@ int snd_pcm_kernel_ioctl(struct snd_pcm_substream *substream,
 	case SNDRV_PCM_IOCTL_START:
 		return snd_pcm_start_lock_irq(substream);
 	case SNDRV_PCM_IOCTL_DRAIN:
-		snd_power_lock(substream->pcm->card);
-		err = snd_pcm_drain(substream, NULL);
-		snd_power_unlock(substream->pcm->card);
-		return err;
+		return snd_pcm_drain(substream, NULL);
 	case SNDRV_PCM_IOCTL_DROP:
 		return snd_pcm_drop(substream);
 	case SNDRV_PCM_IOCTL_DELAY:

sound/soc/soc-core.c

@@ -653,9 +653,7 @@ int snd_soc_suspend(struct device *dev)
 	/* Due to the resume being scheduled into a workqueue we could
 	* suspend before that's finished - wait for it to complete.
 	 */
-	snd_power_lock(card->snd_card);
 	snd_power_wait(card->snd_card, SNDRV_CTL_POWER_D0);
-	snd_power_unlock(card->snd_card);
 
 	/* we're going to block userspace touching us until resume completes */
 	snd_power_change_state(card->snd_card, SNDRV_CTL_POWER_D3hot);