diff --git a/[refs] b/[refs]
index 458320dbf5a9..00e9a2ee79df 100644
--- a/[refs]
+++ b/[refs]
@@ -1,2 +1,2 @@
 ---
-refs/heads/master: 6f23ee1fefdc1f80bd8a3ab04a1c41ab2dec14c9
+refs/heads/master: f38649fee955c19f4df9b9e7267f87702712d973
diff --git a/trunk/drivers/usb/image/mdc800.c b/trunk/drivers/usb/image/mdc800.c
index 63a84bbc310d..d308afd06935 100644
--- a/trunk/drivers/usb/image/mdc800.c
+++ b/trunk/drivers/usb/image/mdc800.c
@@ -565,11 +565,15 @@ static void mdc800_usb_disconnect (struct usb_interface *intf)
 
 		usb_deregister_dev(intf, &mdc800_class);
 
+		/* must be under lock to make sure no URB
+		   is submitted after usb_kill_urb() */
+		mutex_lock(&mdc800->io_lock);
 		mdc800->state=NOT_CONNECTED;
 
 		usb_kill_urb(mdc800->irq_urb);
 		usb_kill_urb(mdc800->write_urb);
 		usb_kill_urb(mdc800->download_urb);
+		mutex_unlock(&mdc800->io_lock);
 
 		mdc800->dev = NULL;
 		usb_set_intfdata(intf, NULL);