USB: introduce usb_anchor

- introduction of usb_anchor and its methods

Signed-off-by: Oliver Neukum <oneukum@suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

drivers/usb/core/hcd.c

@@ -1410,6 +1410,8 @@ void usb_hcd_giveback_urb (struct usb_hcd *hcd, struct urb *urb)
 	}
 
 	usbmon_urb_complete (&hcd->self, urb);
+	usb_unanchor_urb(urb);
+
 	/* pass ownership to the completion handler */
 	urb->complete (urb);
 	atomic_dec (&urb->use_count);