[PATCH 1/5] ALSA: usx2y: Use snd_card_free_when_closed() at disconnection

[Takashi Iwai <tiwai@xxxxxxx>]

The USB disconnect callback is supposed to be short and not too-long
waiting.  OTOH, the current code uses snd_card_free() at
disconnection, but this waits for the close of all used fds, hence it
can take long.  It eventually blocks the upper layer USB ioctls, which
may trigger a soft lockup.

An easy workaround is to replace snd_card_free() with
snd_card_free_when_closed().  This variant returns immediately while
the release of resources is done asynchronously by the card device
release at the last close.

Fixes: 230cd5e24853 ("[ALSA] prevent oops & dead keyboard on usb unplugging while the device is be ing used")
Reported-by: syzbot+73582d08864d8268b6fd@xxxxxxxxxxxxxxxxxxxxxxxxx
Closes: https://syzkaller.appspot.com/bug?extid=73582d08864d8268b6fd
Signed-off-by: Takashi Iwai <tiwai@xxxxxxx>
---
 sound/usb/usx2y/usbusx2y.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/sound/usb/usx2y/usbusx2y.c b/sound/usb/usx2y/usbusx2y.c
index 2f9cede242b3..5f81c68fd42b 100644
--- a/sound/usb/usx2y/usbusx2y.c
+++ b/sound/usb/usx2y/usbusx2y.c
@@ -422,7 +422,7 @@ static void snd_usx2y_disconnect(struct usb_interface *intf)
 	}
 	if (usx2y->us428ctls_sharedmem)
 		wake_up(&usx2y->us428ctls_wait_queue_head);
-	snd_card_free(card);
+	snd_card_free_when_closed(card);
 }
 
 static int snd_usx2y_probe(struct usb_interface *intf,
-- 
2.43.0