gro: Optimise Ethernet header comparison

This patch optimises the Ethernet header comparison to use 2-byte
and 4-byte xors instead of memcmp.  In order to facilitate this,
the actual comparison is now carried out by the callers of the
shared dev_gro_receive function.

This has a significant impact when receiving 1500B packets through
10GbE.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 3 insertions, 1 deletions

diff --git a/net/8021q/vlan_core.c b/net/8021q/vlan_core.c
index 378fa69d625a..70435af153f2 100644
--- a/net/8021q/vlan_core.c
+++ b/net/8021q/vlan_core.c
@@ -85,7 +85,9 @@ static int vlan_gro_common(struct napi_struct *napi, struct vlan_group *grp,
                 goto drop;
 
         for (p = napi->gro_list; p; p = p->next) {
-                NAPI_GRO_CB(p)->same_flow = p->dev == skb->dev;
+                NAPI_GRO_CB(p)->same_flow =
+                        p->dev == skb->dev && !compare_ether_header(
+                                skb_mac_header(p), skb_gro_mac_header(skb));
                 NAPI_GRO_CB(p)->flush = 0;
         }