ALSA: seq: midi: 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/20240227085306.9764-18-tiwai@suse.de

sound/core/seq/seq_midi.c

@@ -302,22 +302,19 @@ snd_seq_midisynth_probe(struct device *_dev)
 	if (ports > (256 / SNDRV_RAWMIDI_DEVICES))
 		ports = 256 / SNDRV_RAWMIDI_DEVICES;
 
-	mutex_lock(&register_mutex);
+	guard(mutex)(&register_mutex);
 	client = synths[card->number];
 	if (client == NULL) {
 		newclient = 1;
 		client = kzalloc(sizeof(*client), GFP_KERNEL);
-		if (client == NULL) {
-			mutex_unlock(&register_mutex);
+		if (client == NULL)
 			return -ENOMEM;
-		}
 		client->seq_client =
 			snd_seq_create_kernel_client(
 				card, 0, "%s", card->shortname[0] ?
 				(const char *)card->shortname : "External MIDI");
 		if (client->seq_client < 0) {
 			kfree(client);
-			mutex_unlock(&register_mutex);
 			return -ENOMEM;
 		}
 	}
@@ -398,7 +395,6 @@ snd_seq_midisynth_probe(struct device *_dev)
 	client->num_ports++;
 	if (newclient)
 		synths[card->number] = client;
-	mutex_unlock(&register_mutex);
 	return 0;	/* success */
 
       __nomem:
@@ -411,7 +407,6 @@ snd_seq_midisynth_probe(struct device *_dev)
 		snd_seq_delete_kernel_client(client->seq_client);
 		kfree(client);
 	}
-	mutex_unlock(&register_mutex);
 	return -ENOMEM;
 }
 
@@ -425,12 +420,10 @@ snd_seq_midisynth_remove(struct device *_dev)
 	struct snd_card *card = dev->card;
 	int device = dev->device, p, ports;
 	
-	mutex_lock(&register_mutex);
+	guard(mutex)(&register_mutex);
 	client = synths[card->number];
-	if (client == NULL || client->ports[device] == NULL) {
-		mutex_unlock(&register_mutex);
+	if (client == NULL || client->ports[device] == NULL)
 		return -ENODEV;
-	}
 	ports = client->ports_per_device[device];
 	client->ports_per_device[device] = 0;
 	msynth = client->ports[device];
@@ -444,7 +437,6 @@ snd_seq_midisynth_remove(struct device *_dev)
 		synths[card->number] = NULL;
 		kfree(client);
 	}
-	mutex_unlock(&register_mutex);
 	return 0;
 }
 

sound/core/seq/seq_midi_event.c

@@ -144,21 +144,15 @@ static inline void reset_encode(struct snd_midi_event *dev)
 
 void snd_midi_event_reset_encode(struct snd_midi_event *dev)
 {
-	unsigned long flags;
-
-	spin_lock_irqsave(&dev->lock, flags);
+	guard(spinlock_irqsave)(&dev->lock);
 	reset_encode(dev);
-	spin_unlock_irqrestore(&dev->lock, flags);
 }
 EXPORT_SYMBOL(snd_midi_event_reset_encode);
 
 void snd_midi_event_reset_decode(struct snd_midi_event *dev)
 {
-	unsigned long flags;
-
-	spin_lock_irqsave(&dev->lock, flags);
+	guard(spinlock_irqsave)(&dev->lock);
 	dev->lastcmd = 0xff;
-	spin_unlock_irqrestore(&dev->lock, flags);
 }
 EXPORT_SYMBOL(snd_midi_event_reset_decode);
 
@@ -177,7 +171,6 @@ bool snd_midi_event_encode_byte(struct snd_midi_event *dev, unsigned char c,
 				struct snd_seq_event *ev)
 {
 	bool rc = false;
-	unsigned long flags;
 
 	if (c >= MIDI_CMD_COMMON_CLOCK) {
 		/* real-time event */
@@ -187,7 +180,7 @@ bool snd_midi_event_encode_byte(struct snd_midi_event *dev, unsigned char c,
 		return ev->type != SNDRV_SEQ_EVENT_NONE;
 	}
 
-	spin_lock_irqsave(&dev->lock, flags);
+	guard(spinlock_irqsave)(&dev->lock);
 	if ((c & 0x80) &&
 	    (c != MIDI_CMD_COMMON_SYSEX_END || dev->type != ST_SYSEX)) {
 		/* new command */
@@ -236,7 +229,6 @@ bool snd_midi_event_encode_byte(struct snd_midi_event *dev, unsigned char c,
 		}
 	}
 
-	spin_unlock_irqrestore(&dev->lock, flags);
 	return rc;
 }
 EXPORT_SYMBOL(snd_midi_event_encode_byte);