[PATCH] ALSA:usb-audio:check urb before kill it

[Defang Bo]

Similar to commit<124751d5e>, there should be a check for urb before kill it.

Signed-off-by: Defang Bo <bodefang@xxxxxxx>
---
 sound/usb/mixer.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/sound/usb/mixer.c b/sound/usb/mixer.c
index 81e987e..0223ef3 100644
--- a/sound/usb/mixer.c
+++ b/sound/usb/mixer.c
@@ -3589,8 +3589,10 @@ void snd_usb_mixer_disconnect(struct usb_mixer_interface *mixer)
 /* stop any bus activity of a mixer */
 static void snd_usb_mixer_inactivate(struct usb_mixer_interface *mixer)
 {
-	usb_kill_urb(mixer->urb);
-	usb_kill_urb(mixer->rc_urb);
+	if (mixer->urb)
+		usb_kill_urb(mixer->urb);
+	if (mixer->rc_urb)
+		usb_kill_urb(mixer->rc_urb);
 }
 
 static int snd_usb_mixer_activate(struct usb_mixer_interface *mixer)
-- 
2.7.4