true if succeeded to acquire the lock.
false in case of error.
-EINVAL is not an acceptable value, since its promoted to true.
Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com> Acked-by: Eilon Greenstein <eilong@broadcom.com> Signed-off-by: David S. Miller <davem@davemloft.net>