ALSA: core: Use guard() for locking

We can simplify the code gracefully with new guard() macro and co for
automatic cleanup of locks.

Only the code refactoring, and no functional changes.
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Link: https://lore.kernel.org/r/20240227085306.9764-12-tiwai@suse.de

sound/core/sound.c

@@ -103,7 +103,7 @@ void *snd_lookup_minor_data(unsigned int minor, int type)
 
 	if (minor >= ARRAY_SIZE(snd_minors))
 		return NULL;
-	mutex_lock(&sound_mutex);
+	guard(mutex)(&sound_mutex);
 	mreg = snd_minors[minor];
 	if (mreg && mreg->type == type) {
 		private_data = mreg->private_data;
@@ -111,7 +111,6 @@ void *snd_lookup_minor_data(unsigned int minor, int type)
 			get_device(&mreg->card_ptr->card_dev);
 	} else
 		private_data = NULL;
-	mutex_unlock(&sound_mutex);
 	return private_data;
 }
 EXPORT_SYMBOL(snd_lookup_minor_data);
@@ -150,17 +149,15 @@ static int snd_open(struct inode *inode, struct file *file)
 
 	if (minor >= ARRAY_SIZE(snd_minors))
 		return -ENODEV;
-	mutex_lock(&sound_mutex);
-	mptr = snd_minors[minor];
-	if (mptr == NULL) {
-		mptr = autoload_device(minor);
-		if (!mptr) {
-			mutex_unlock(&sound_mutex);
-			return -ENODEV;
+	scoped_guard(mutex, &sound_mutex) {
+		mptr = snd_minors[minor];
+		if (mptr == NULL) {
+			mptr = autoload_device(minor);
+			if (!mptr)
+				return -ENODEV;
 		}
+		new_fops = fops_get(mptr->f_ops);
 	}
-	new_fops = fops_get(mptr->f_ops);
-	mutex_unlock(&sound_mutex);
 	if (!new_fops)
 		return -ENODEV;
 	replace_fops(file, new_fops);
@@ -269,7 +266,7 @@ int snd_register_device(int type, struct snd_card *card, int dev,
 	preg->f_ops = f_ops;
 	preg->private_data = private_data;
 	preg->card_ptr = card;
-	mutex_lock(&sound_mutex);
+	guard(mutex)(&sound_mutex);
 	minor = snd_find_free_minor(type, card, dev);
 	if (minor < 0) {
 		err = minor;
@@ -284,7 +281,6 @@ int snd_register_device(int type, struct snd_card *card, int dev,
 
 	snd_minors[minor] = preg;
  error:
-	mutex_unlock(&sound_mutex);
 	if (err < 0)
 		kfree(preg);
 	return err;
@@ -305,7 +301,7 @@ int snd_unregister_device(struct device *dev)
 	int minor;
 	struct snd_minor *preg;
 
-	mutex_lock(&sound_mutex);
+	guard(mutex)(&sound_mutex);
 	for (minor = 0; minor < ARRAY_SIZE(snd_minors); ++minor) {
 		preg = snd_minors[minor];
 		if (preg && preg->dev == dev) {
@@ -315,7 +311,6 @@ int snd_unregister_device(struct device *dev)
 			break;
 		}
 	}
-	mutex_unlock(&sound_mutex);
 	if (minor >= ARRAY_SIZE(snd_minors))
 		return -ENOENT;
 	return 0;
@@ -355,7 +350,7 @@ static void snd_minor_info_read(struct snd_info_entry *entry, struct snd_info_bu
 	int minor;
 	struct snd_minor *mptr;
 
-	mutex_lock(&sound_mutex);
+	guard(mutex)(&sound_mutex);
 	for (minor = 0; minor < SNDRV_OS_MINORS; ++minor) {
 		mptr = snd_minors[minor];
 		if (!mptr)
@@ -373,7 +368,6 @@ static void snd_minor_info_read(struct snd_info_entry *entry, struct snd_info_bu
 			snd_iprintf(buffer, "%3i:        : %s\n", minor,
 				    snd_device_type_name(mptr->type));
 	}
-	mutex_unlock(&sound_mutex);
 }
 
 int __init snd_minor_info_init(void)

sound/core/sound_oss.c

@@ -29,7 +29,7 @@ void *snd_lookup_oss_minor_data(unsigned int minor, int type)
 
 	if (minor >= ARRAY_SIZE(snd_oss_minors))
 		return NULL;
-	mutex_lock(&sound_oss_mutex);
+	guard(mutex)(&sound_oss_mutex);
 	mreg = snd_oss_minors[minor];
 	if (mreg && mreg->type == type) {
 		private_data = mreg->private_data;
@@ -37,7 +37,6 @@ void *snd_lookup_oss_minor_data(unsigned int minor, int type)
 			get_device(&mreg->card_ptr->card_dev);
 	} else
 		private_data = NULL;
-	mutex_unlock(&sound_oss_mutex);
 	return private_data;
 }
 EXPORT_SYMBOL(snd_lookup_oss_minor_data);
@@ -106,7 +105,7 @@ int snd_register_oss_device(int type, struct snd_card *card, int dev,
 	preg->f_ops = f_ops;
 	preg->private_data = private_data;
 	preg->card_ptr = card;
-	mutex_lock(&sound_oss_mutex);
+	guard(mutex)(&sound_oss_mutex);
 	snd_oss_minors[minor] = preg;
 	minor_unit = SNDRV_MINOR_OSS_DEVICE(minor);
 	switch (minor_unit) {
@@ -130,7 +129,6 @@ int snd_register_oss_device(int type, struct snd_card *card, int dev,
 			goto __end;
 		snd_oss_minors[track2] = preg;
 	}
-	mutex_unlock(&sound_oss_mutex);
 	return 0;
 
       __end:
@@ -139,7 +137,6 @@ int snd_register_oss_device(int type, struct snd_card *card, int dev,
       	if (register1 >= 0)
       		unregister_sound_special(register1);
 	snd_oss_minors[minor] = NULL;
-	mutex_unlock(&sound_oss_mutex);
 	kfree(preg);
       	return -EBUSY;
 }
@@ -156,12 +153,10 @@ int snd_unregister_oss_device(int type, struct snd_card *card, int dev)
 		return 0;
 	if (minor < 0)
 		return minor;
-	mutex_lock(&sound_oss_mutex);
+	guard(mutex)(&sound_oss_mutex);
 	mptr = snd_oss_minors[minor];
-	if (mptr == NULL) {
-		mutex_unlock(&sound_oss_mutex);
+	if (mptr == NULL)
 		return -ENOENT;
-	}
 	switch (SNDRV_MINOR_OSS_DEVICE(minor)) {
 	case SNDRV_MINOR_OSS_PCM:
 		track2 = SNDRV_MINOR_OSS(cidx, SNDRV_MINOR_OSS_AUDIO);
@@ -176,7 +171,6 @@ int snd_unregister_oss_device(int type, struct snd_card *card, int dev)
 	if (track2 >= 0)
 		snd_oss_minors[track2] = NULL;
 	snd_oss_minors[minor] = NULL;
-	mutex_unlock(&sound_oss_mutex);
 
 	/* call unregister_sound_special() outside sound_oss_mutex;
 	 * otherwise may deadlock, as it can trigger the release of a card
@@ -220,7 +214,7 @@ static void snd_minor_info_oss_read(struct snd_info_entry *entry,
 	int minor;
 	struct snd_minor *mptr;
 
-	mutex_lock(&sound_oss_mutex);
+	guard(mutex)(&sound_oss_mutex);
 	for (minor = 0; minor < SNDRV_OSS_MINORS; ++minor) {
 		mptr = snd_oss_minors[minor];
 		if (!mptr)
@@ -233,7 +227,6 @@ static void snd_minor_info_oss_read(struct snd_info_entry *entry,
 			snd_iprintf(buffer, "%3i:       : %s\n", minor,
 				    snd_oss_device_type_name(mptr->type));
 	}
-	mutex_unlock(&sound_oss_mutex);
 }