This series adds a helper to allow head adjusting in XDP prog. mlx4 driver has been modified to support this feature. An example is written to encapsulate a packet with an IPv4/v6 header and then XDP_TX it out.
v2: 1. Make a variable name change in bpf_xdp_adjust_head() in patch 1 2. Ensure no less than ETH_HLEN data in bpf_xdp_adjust_head() in patch 1 3. Some clarifications in commit log messages of patch 2 and 3 Thanks, --Martin
