From 03d56daafe9d4e04a8a0d305789cd3eda250746b Mon Sep 17 00:00:00 2001 From: Tom Herbert Date: Tue, 9 Sep 2014 11:23:14 -0700 Subject: [PATCH] ipv6: Clear flush_id to make GRO work In TCP gro we check flush_id which is derived from the IP identifier. In IPv4 gro path the flush_id is set with the expectation that every matched packet increments IP identifier. In IPv6, the flush_id is never set and thus is uinitialized. What's worse is that in IPv6 over IPv4 encapsulation, the IP identifier is taken from the outer header which is currently not incremented on every packet for Linux stack, so GRO in this case never matches packets (identifier is not increasing). This patch clears flush_id for every time for a matched packet in IPv6 gro_receive. We need to do this each time to overwrite the setting that would be done in IPv4 gro_receive per the outer header in IPv6 over Ipv4 encapsulation. Signed-off-by: Tom Herbert Signed-off-by: Eric Dumazet Signed-off-by: David S. Miller --- net/ipv6/ip6_offload.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/net/ipv6/ip6_offload.c b/net/ipv6/ip6_offload.c index 5bcda338bcef..929bbbcd0c8e 100644 --- a/net/ipv6/ip6_offload.c +++ b/net/ipv6/ip6_offload.c @@ -261,6 +261,9 @@ static struct sk_buff **ipv6_gro_receive(struct sk_buff **head, /* flush if Traffic Class fields are different */ NAPI_GRO_CB(p)->flush |= !!(first_word & htonl(0x0FF00000)); NAPI_GRO_CB(p)->flush |= flush; + + /* Clear flush_id, there's really no concept of ID in IPv6. */ + NAPI_GRO_CB(p)->flush_id = 0; } NAPI_GRO_CB(skb)->flush |= flush; -- 2.20.1