Merge branch 'tpacket-gso-csum-offload'

Willem de Bruijn says:

====================
packet: tpacket gso and csum offload

Extend PACKET_VNET_HDR socket option support to packet sockets with
memory mapped rings.

Patches 2 and 4 add support to tpacket_rcv and tpacket_snd.

Patch 1 prepares for this by moving the relevant virtio_net_hdr
logic out of packet_snd and packet_rcv into helper functions.

GSO transmission requires all headers in the skb linear section.
Patch 3 moves parsing of tx_ring slot headers before skb allocation
to enable allocation with sufficient linear size.

Changes
  v1->v2:
    - fix bounds checks:
      - subtract sizeof(vnet_hdr) before comparing tp_len to size_max
      - compare tp_len to size_max also with GSO, just do not truncate to MTU
====================
Signed-off-by: David S. Miller <davem@davemloft.net>