To fix the bug of checking on signed return value using unsigned statement.
Thanks Roel Kluin for digging out it.
Signed-off-by: Roel Kluin <roel.kluin@gmail.com>
Signed-off-by: Wan ZongShun <mcuos.com@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>