5.15-stable review patch. If anyone has any objections, please let me know.
------------------
From: Tzung-Bi Shih <tzungbi@kernel.org>
Commit 46397622a3fa ("ALSA: seq: Add UMP support") mistakenly removed
the `snd_seq_port_unlock(src_port)` call in deliver_to_subscribers().
As a result, every time an event is delivered to a subscriber, the
source port's `use_lock` atomic counter is increased but never
decreased.
The leak prevents ALSA sequencer ports from closing cleanly. When the
client process exits or destroys the port, port_delete() hangs forever
at snd_use_lock_sync(). The process becomes stuck in an unkillable D
state, triggering the following warning:
ALSA: seq_lock: waiting [1 left] in sound/core/seq/seq_ports.c:250
Restore the missing `snd_seq_port_unlock(src_port)`.
Note that commit 177ccf811df4 ("ALSA: seq: Support MIDI 2.0 UMP Endpoint
port") incidentally resolved this issue upstream when it refactored the
locking logic into a wrapper function. However, since the commit
introduces a new feature and might not be suitable for stable release
branches, this targeted fix is necessary.
Fixes: 6389f2c13531 ("ALSA: seq: Add UMP support")
Signed-off-by: Tzung-Bi Shih <tzungbi@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
sound/core/seq/seq_clientmgr.c | 1 +
1 file changed, 1 insertion(+)
diff --git a/sound/core/seq/seq_clientmgr.c b/sound/core/seq/seq_clientmgr.c
index f2feeb97765c5..bd2d7a9fab5b8 100644
--- a/sound/core/seq/seq_clientmgr.c
+++ b/sound/core/seq/seq_clientmgr.c
@@ -733,6 +733,7 @@ static int deliver_to_subscribers(struct snd_seq_client *client,
read_unlock(&grp->list_lock);
else
up_read(&grp->list_mutex);
+ snd_seq_port_unlock(src_port);
memcpy(event, &event_saved, saved_size);
return (result < 0) ? result : num_ev;
}
--
2.53.0