[PATCH 2/5] ALSA: us122l: 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.

The loop of us122l->mmap_count check is dropped as well.  The check is
useless for the asynchronous operation with *_when_closed().

Fixes: 030a07e44129 ("ALSA: Add USB US122L driver")
Signed-off-by: Takashi Iwai <tiwai@xxxxxxx>
---
 sound/usb/usx2y/us122l.c | 5 +----
 1 file changed, 1 insertion(+), 4 deletions(-)

diff --git a/sound/usb/usx2y/us122l.c b/sound/usb/usx2y/us122l.c
index 1be0e980feb9..ca5fac03ec79 100644
--- a/sound/usb/usx2y/us122l.c
+++ b/sound/usb/usx2y/us122l.c
@@ -606,10 +606,7 @@ static void snd_us122l_disconnect(struct usb_interface *intf)
 	usb_put_intf(usb_ifnum_to_if(us122l->dev, 1));
 	usb_put_dev(us122l->dev);
 
-	while (atomic_read(&us122l->mmap_count))
-		msleep(500);
-
-	snd_card_free(card);
+	snd_card_free_when_closed(card);
 }
 
 static int snd_us122l_suspend(struct usb_interface *intf, pm_message_t message)
-- 
2.43.0