ALSA: seq: oss: Fix unbalanced use lock for synth MIDI device

When get_synthdev() is called for a MIDI device, it returns the fixed midi_synth_dev without the use refcounting. OTOH, the caller is supposed to unreference unconditionally after the usage, so this would lead to unbalanced refcount. This patch corrects the behavior and keep up the refcount balance also for the MIDI synth device. Cc: <[email protected]> Signed-off-by: Takashi Iwai <[email protected]>
mrcsosa · Apr 25, 2018 · f5e94b4 · f5e94b4
1 parent ab3b8e5
commit f5e94b4
Showing 1 changed file with 8 additions and 4 deletions.
diff --git a/sound/core/seq/oss/seq_oss_synth.c b/sound/core/seq/oss/seq_oss_synth.c
@@ -363,10 +363,14 @@ get_synthdev(struct seq_oss_devinfo *dp, int dev)
 		return NULL;
 	if (! dp->synths[dev].opened)
 		return NULL;
-	if (dp->synths[dev].is_midi)
-		return &midi_synth_dev;
-	if ((rec = get_sdev(dev)) == NULL)
-		return NULL;
+	if (dp->synths[dev].is_midi) {
+		rec = &midi_synth_dev;
+		snd_use_lock_use(&rec->use_lock);
+	} else {
+		rec = get_sdev(dev);
+		if (!rec)
+			return NULL;
+	}
 	if (! rec->opened) {
 		snd_use_lock_free(&rec->use_lock);
 		return NULL;