[PATCH RFC 0/2] Convert GRO receive over to hash table.

When many parallel flows are present and being received on the same
RX queue, GRO processing can become expensive because each incoming
frame must traverse the per-NAPI GRO list at each protocol layer
of GRO receive (eth --> ipv{4,6} --> tcp).

Use the already computed hash to chain these SKBs in a hash table
instead of a simple list.

The first patch makes the GRO list a true list_head.

The second patch implements the hash table.

This series patches basic testing and I added some diagnostics
to make sure we really were aggregating GRO frames :-)

Signed-off-by: David S. Miller <davem@davemloft.net>