From: Eric Dumazet <edumazet@xxxxxxxxxx>
commit 45f00f99d6e ("ipv4: tcp: clean up tcp_v4_early_demux()") added a
performance regression for non GRO traffic, basically disabling
IP early demux.
IPv6 stack resets transport header in ip6_rcv() before calling
IP early demux in ip6_rcv_finish(), while IPv4 does this only in
ip_local_deliver_finish(), _after_ IP early demux.
GRO traffic happened to enable IP early demux because transport header
is also set in inet_gro_receive()
Instead of reverting the faulty commit, we can make IPv4/IPv6 behave the
same : transport_header should be set in ip_rcv() instead of
ip_local_deliver_finish()
ip_local_deliver_finish() can also use skb_network_header_len() which is
faster than ip_hdrlen()
Signed-off-by: Eric Dumazet <edumazet@xxxxxxxxxx>
Cc: Neal Cardwell <ncardwell@xxxxxxxxxx>
Cc: Tom Herbert <therbert@xxxxxxxxxx>
---
net/ipv4/ip_input.c | 7 +++----
1 file changed, 3 insertions(+), 4 deletions(-)
diff --git a/net/ipv4/ip_input.c b/net/ipv4/ip_input.c
index 3da817b..15e3e68 100644
--- a/net/ipv4/ip_input.c
+++ b/net/ipv4/ip_input.c
@@ -190,10 +190,7 @@ static int ip_local_deliver_finish(struct sk_buff *skb)
{
struct net *net = dev_net(skb->dev);
- __skb_pull(skb, ip_hdrlen(skb));
-
- /* Point into the IP datagram, just past the header. */
- skb_reset_transport_header(skb);
+ __skb_pull(skb, skb_network_header_len(skb));
rcu_read_lock();
{
@@ -437,6 +434,8 @@ int ip_rcv(struct sk_buff *skb, struct net_device *dev, struct packet_type *pt,
goto drop;
}
+ skb->transport_header = skb->network_header + iph->ihl*4;
+
/* Remove any debris in the socket control block */
memset(IPCB(skb), 0, sizeof(struct inet_skb_parm));
--
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