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Subject[ 67/85] ipv6: GRO should be ECN friendly
Date
3.6-stable review patch.  If anyone has any objections, please let me know.

------------------


From: Eric Dumazet <edumazet@google.com>

[ Upstream commit 51ec04038c113a811b177baa85d293feff9ce995 ]

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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
net/ipv6/af_inet6.c | 11 +++++++----
1 file changed, 7 insertions(+), 4 deletions(-)

--- a/net/ipv6/af_inet6.c
+++ b/net/ipv6/af_inet6.c
@@ -880,22 +880,25 @@ static struct sk_buff **ipv6_gro_receive
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;
}




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