ALSA: seq: oss: Use scoped cleanup for temporary MIDI use lock

The OSS sequencer write and out-of-band paths may receive a temporary
snd_use_lock_t reference from snd_seq_oss_process_event(). This was added
to keep MIDI device data alive until events with embedded SysEx data are
dispatched.

Use a scoped cleanup helper for that temporary reference. This keeps the
lifetime rule local to the variable declaration and avoids future missing
snd_use_lock_free() paths if these event handling paths gain more exits.

No functional change is intended.

Signed-off-by: Cássio Gabriel <cassiogabrielcontato@gmail.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Link: https://patch.msgid.link/20260604-alsa-scoped-cleanups-v1-3-10c43152a728@gmail.com

3 files changed, 7 insertions, 9 deletions

diff --git a/sound/core/seq/oss/seq_oss_event.h b/sound/core/seq/oss/seq_oss_event.h
index a4524e51d0e9..54da1f810b3a 100644
--- a/sound/core/seq/oss/seq_oss_event.h
+++ b/sound/core/seq/oss/seq_oss_event.h
@@ -96,5 +96,6 @@ int snd_seq_oss_process_event(struct seq_oss_devinfo *dp, union evrec *q,
 int snd_seq_oss_process_timer_event(struct seq_oss_timer *rec, union evrec *q);
 int snd_seq_oss_event_input(struct snd_seq_event *ev, int direct, void *private_data, int atomic, int hop);
 
+DEFINE_FREE(seq_oss_use_lock, snd_use_lock_t *, if (_T) snd_use_lock_free(_T))
 
 #endif /* __SEQ_OSS_EVENT_H */
diff --git a/sound/core/seq/oss/seq_oss_ioctl.c b/sound/core/seq/oss/seq_oss_ioctl.c
index ce7a69d52b30..f1a79776773f 100644
--- a/sound/core/seq/oss/seq_oss_ioctl.c
+++ b/sound/core/seq/oss/seq_oss_ioctl.c
@@ -45,18 +45,17 @@ static int snd_seq_oss_oob_user(struct seq_oss_devinfo *dp, void __user *arg)
 {
 	unsigned char ev[8];
 	struct snd_seq_event tmpev;
-	snd_use_lock_t *lock = NULL;
 
 	if (copy_from_user(ev, arg, 8))
 		return -EFAULT;
 	memset(&tmpev, 0, sizeof(tmpev));
 	snd_seq_oss_fill_addr(dp, &tmpev, dp->addr.client, dp->addr.port);
 	tmpev.time.tick = 0;
-	if (!snd_seq_oss_process_event(dp, (union evrec *)ev, &tmpev, &lock)) {
+
+	snd_use_lock_t *lock __free(seq_oss_use_lock) = NULL;
+
+	if (!snd_seq_oss_process_event(dp, (union evrec *)ev, &tmpev, &lock))
 		snd_seq_oss_dispatch(dp, &tmpev, 0, 0);
-		if (lock)
-			snd_use_lock_free(lock);
-	}
 	return 0;
 }
 
@@ -178,4 +177,3 @@ snd_seq_oss_ioctl(struct seq_oss_devinfo *dp, unsigned int cmd, unsigned long ca
 	}
 	return 0;
 }
-
diff --git a/sound/core/seq/oss/seq_oss_rw.c b/sound/core/seq/oss/seq_oss_rw.c
index b7147ac78ee8..6e417b10a102 100644
--- a/sound/core/seq/oss/seq_oss_rw.c
+++ b/sound/core/seq/oss/seq_oss_rw.c
@@ -154,7 +154,6 @@ insert_queue(struct seq_oss_devinfo *dp, union evrec *rec, struct file *opt)
 {
 	int rc = 0;
 	struct snd_seq_event event;
-	snd_use_lock_t *lock = NULL;
 
 	/* if this is a timing event, process the current time */
 	if (snd_seq_oss_process_timer_event(dp->timer, rec))
@@ -166,6 +165,8 @@ insert_queue(struct seq_oss_devinfo *dp, union evrec *rec, struct file *opt)
 	event.type = SNDRV_SEQ_EVENT_NOTEOFF;
 	snd_seq_oss_fill_addr(dp, &event, dp->addr.client, dp->addr.port);
 
+	snd_use_lock_t *lock __free(seq_oss_use_lock) = NULL;
+
 	if (snd_seq_oss_process_event(dp, rec, &event, &lock))
 		return 0; /* invalid event - no need to insert queue */
 
@@ -175,8 +176,6 @@ insert_queue(struct seq_oss_devinfo *dp, union evrec *rec, struct file *opt)
 	else
 		rc = snd_seq_kernel_client_enqueue(dp->cseq, &event, opt,
 						   !is_nonblock_mode(dp->file_mode));
-	if (lock)
-		snd_use_lock_free(lock);
 	return rc;
 }