usb_free_urb() can take a NULL, so let's check and warn about that.
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>
Signed-off-by: NAndy Whitcroft <apw@shadowen.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>