From db8caf3dbc77599dc90f4ea0a803cd1d97116f30 Mon Sep 17 00:00:00 2001
From: Eric Dumazet <edumazet@google.com>
Date: Fri, 31 May 2013 11:18:10 +0000
Subject: [PATCH] gro: should aggregate frames without DF
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>
---
net/ipv4/af_inet.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/net/ipv4/af_inet.c b/net/ipv4/af_inet.c
index b05ae96aec44..9c090c7daea1 100644
--- a/net/ipv4/af_inet.c
+++ b/net/ipv4/af_inet.c
@@ -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;
--
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