ALSA: seq: ump: 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/20240227085306.9764-19-tiwai@suse.de

sound/core/seq/seq_ump_client.c

@@ -115,21 +115,19 @@ static int seq_ump_process_event(struct snd_seq_event *ev, int direct,
 static int seq_ump_client_open(struct seq_ump_client *client, int dir)
 {
 	struct snd_ump_endpoint *ump = client->ump;
-	int err = 0;
+	int err;
 
-	mutex_lock(&ump->open_mutex);
+	guard(mutex)(&ump->open_mutex);
 	if (dir == STR_OUT && !client->opened[dir]) {
 		err = snd_rawmidi_kernel_open(&ump->core, 0,
 					      SNDRV_RAWMIDI_LFLG_OUTPUT |
 					      SNDRV_RAWMIDI_LFLG_APPEND,
 					      &client->out_rfile);
 		if (err < 0)
-			goto unlock;
+			return err;
 	}
 	client->opened[dir]++;
- unlock:
-	mutex_unlock(&ump->open_mutex);
-	return err;
+	return 0;
 }
 
 /* close the rawmidi */
@@ -137,11 +135,10 @@ static int seq_ump_client_close(struct seq_ump_client *client, int dir)
 {
 	struct snd_ump_endpoint *ump = client->ump;
 
-	mutex_lock(&ump->open_mutex);
+	guard(mutex)(&ump->open_mutex);
 	if (!--client->opened[dir])
 		if (dir == STR_OUT)
 			snd_rawmidi_kernel_release(&client->out_rfile);
-	mutex_unlock(&ump->open_mutex);
 	return 0;
 }