The check for length <= 0 is bogus because length is unsigned, and network
stack never sends zero length packets (unless it is totally broken).

The check for really small packets can be optimized (using unlikely)
and calling skb_pad directly.
Signed-off-by: NStephen Hemminger <shemminger@vyatta.com>
Tested-by: NPhil Schmitt <phillip.j.schmitt@intel.com>
Signed-off-by: NJeff Kirsher <jeffrey.t.kirsher@intel.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>