ipv6: GRO should be ECN friendly

IPv4 side of the problem was addressed in commit a9e050f4e7f9d
(net: tcp: GRO should be ECN friendly)

This patch does the same, but for IPv6 : A Traffic Class mismatch
doesnt mean flows are different, but instead should force a flush
of previous packets.

This patch removes artificial packet reordering problem.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/net/ipv6/af_inet6.c b/net/ipv6/af_inet6.c
index e22e6d88bac68173ecd6ca06e5bb7161583910ff..f757e3b7cfbfbb969fea039a578de2791925a2ad 100644 (file)
--- a/net/ipv6/af_inet6.c
+++ b/net/ipv6/af_inet6.c
@@ -880,22 +880,25 @@ static struct sk_buff **ipv6_gro_receive(struct sk_buff **head,
        nlen = skb_network_header_len(skb);
 
        for (p = *head; p; p = p->next) {
-               struct ipv6hdr *iph2;
+               const struct ipv6hdr *iph2;
+               __be32 first_word; /* <Version:4><Traffic_Class:8><Flow_Label:20> */
 
                if (!NAPI_GRO_CB(p)->same_flow)
                        continue;
 
                iph2 = ipv6_hdr(p);
+               first_word = *(__be32 *)iph ^ *(__be32 *)iph2 ;
 
-               /* All fields must match except length. */
+               /* All fields must match except length and Traffic Class. */
                if (nlen != skb_network_header_len(p) ||
-                   memcmp(iph, iph2, offsetof(struct ipv6hdr, payload_len)) ||
+                   (first_word & htonl(0xF00FFFFF)) ||
                    memcmp(&iph->nexthdr, &iph2->nexthdr,
                           nlen - offsetof(struct ipv6hdr, nexthdr))) {
                        NAPI_GRO_CB(p)->same_flow = 0;
                        continue;
                }
-
+               /* flush if Traffic Class fields are different */
+               NAPI_GRO_CB(p)->flush |= !!(first_word & htonl(0x0FF00000));
                NAPI_GRO_CB(p)->flush |= flush;
        }