ALSA: seq: oss: Clean up core code with guard()

Replace the manual mutex lock/unlock pairs with guard() for code
simplification.

Only code refactoring, and no behavior change.

Signed-off-by: Takashi Iwai <[e-mail]>
Link: https://patch.msgid.link/[e-mail]

sound/core/seq/oss/seq_oss.c

···
 static int
 odev_open(struct inode *inode, struct file *file)
 {
-	int level, rc;
+	int level;
 
 	if (iminor(inode) == SNDRV_MINOR_OSS_MUSIC)
 		level = SNDRV_SEQ_OSS_MODE_MUSIC;
 	else
 		level = SNDRV_SEQ_OSS_MODE_SYNTH;
 
-	mutex_lock(&register_mutex);
-	rc = snd_seq_oss_open(file, level);
-	mutex_unlock(&register_mutex);
-
-	return rc;
+	guard(mutex)(&register_mutex);
+	return snd_seq_oss_open(file, level);
 }
 
 static int
···
 	if (!dp)
 		return 0;
 
-	mutex_lock(&register_mutex);
+	guard(mutex)(&register_mutex);
 	snd_seq_oss_release(dp);
-	mutex_unlock(&register_mutex);
-
 	return 0;
 }
 
···
 {
 	int rc;
 
-	mutex_lock(&register_mutex);
+	guard(mutex)(&register_mutex);
 	rc = snd_register_oss_device(SNDRV_OSS_DEVICE_TYPE_SEQUENCER,
 				     NULL, 0,
 				     &seq_oss_f_ops, NULL);
 	if (rc < 0) {
 		pr_err("ALSA: seq_oss: can't register device seq\n");
-		mutex_unlock(&register_mutex);
 		return rc;
 	}
 	rc = snd_register_oss_device(SNDRV_OSS_DEVICE_TYPE_MUSIC,
···
 	if (rc < 0) {
 		pr_err("ALSA: seq_oss: can't register device music\n");
 		snd_unregister_oss_device(SNDRV_OSS_DEVICE_TYPE_SEQUENCER, NULL, 0);
-		mutex_unlock(&register_mutex);
 		return rc;
 	}
-	mutex_unlock(&register_mutex);
 	return 0;
 }
 
 static void
 unregister_device(void)
 {
-	mutex_lock(&register_mutex);
+	guard(mutex)(&register_mutex);
 	if (snd_unregister_oss_device(SNDRV_OSS_DEVICE_TYPE_MUSIC, NULL, 0) < 0)		
 		pr_err("ALSA: seq_oss: error unregister device music\n");
 	if (snd_unregister_oss_device(SNDRV_OSS_DEVICE_TYPE_SEQUENCER, NULL, 0) < 0)
 		pr_err("ALSA: seq_oss: error unregister device seq\n");
-	mutex_unlock(&register_mutex);
 }
 
 /*
···
 static void
 info_read(struct snd_info_entry *entry, struct snd_info_buffer *buf)
 {
-	mutex_lock(&register_mutex);
+	guard(mutex)(&register_mutex);
 	snd_iprintf(buf, "OSS sequencer emulation version %s\n", SNDRV_SEQ_OSS_VERSION_STR);
 	snd_seq_oss_system_info_read(buf);
 	snd_seq_oss_synth_info_read(buf);
 	snd_seq_oss_midi_info_read(buf);
-	mutex_unlock(&register_mutex);
 }