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gro: should aggregate frames without DF

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GRO on IPv4 doesn't aggregate frames if they don't have DF bit set.

Some servers use IP_MTU_DISCOVER/IP_PMTUDISC_PROBE, so linux receivers
are unable to aggregate this kind of traffic.

The right thing to do is to allow aggregation as long as the DF bit has
same value on all segments.

bnx2x LRO does this correctly.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Jerry Chu <hkchu@google.com>
Cc: Herbert Xu <herbert@gondor.apana.org.au>
Cc: Ben Hutchings <bhutchings@solarflare.com>
Reviewed-by: Ben Hutchings <bhutchings@solarflare.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Eric Dumazet 2013-05-31 11:18:10 +00:00 committed by David S. Miller
parent c3f1dbaf6e
commit db8caf3dbc
1 changed files with 2 additions and 1 deletions
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3
net/ipv4/af_inet.c
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@ -1385,7 +1385,7 @@ static struct sk_buff **inet_gro_receive(struct sk_buff **head,
goto out_unlock;
id = ntohl(*(__be32 *)&iph->id);
flush = (u16)((ntohl(*(__be32 *)iph) ^ skb_gro_len(skb)) | (id ^ IP_DF));
flush = (u16)((ntohl(*(__be32 *)iph) ^ skb_gro_len(skb)) | (id & ~IP_DF));
id >>= 16;
for (p = *head; p; p = p->next) {
@ -1407,6 +1407,7 @@ static struct sk_buff **inet_gro_receive(struct sk_buff **head,
NAPI_GRO_CB(p)->flush |=
(iph->ttl ^ iph2->ttl) |
(iph->tos ^ iph2->tos) |
((iph->frag_off ^ iph2->frag_off) & htons(IP_DF)) |
((u16)(ntohs(iph2->id) + NAPI_GRO_CB(p)->count) ^ id);
NAPI_GRO_CB(p)->flush |= flush;