netdev - Re: [PATCH] ipv4: fix TCP early demux

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Date:	Fri, 27 Jul 2012 23:34:33 +0200
From:	Eric Dumazet <eric.dumazet@...il.com>
To:	David Miller <davem@...emloft.net>
Cc:	netdev@...r.kernel.org
Subject: Re: [PATCH] ipv4: fix TCP early demux

On Fri, 2012-07-27 at 13:47 -0700, David Miller wrote:
> From: Eric Dumazet <eric.dumazet@...il.com>
> Date: Fri, 27 Jul 2012 18:23:40 +0200
> 
> > From: Eric Dumazet <edumazet@...gle.com>
> > 
> > commit 92101b3b2e317 (ipv4: Prepare for change of rt->rt_iif encoding.)
> > invalidated TCP early demux, because rx_dst_ifindex is not properly
> > initialized and checked.
> > 
> > Also remove the use of inet_iif(skb) in favor or skb->skb_iif
> > 
> > Signed-off-by: Eric Dumazet <edumazet@...gle.com>
> 
> Applied.

Thanks David

IPv6 part is screwed because of the bogus dst_check(dst, 0)

(and missing code that was moved out from tcp_rcv_established() to
tcp_v4_do_rcv() : I was wondering if we could make it generic to move it
back to tcp_rcv_established()) :

                if (sk->sk_rx_dst) {
                        struct dst_entry *dst = sk->sk_rx_dst;
                        if (dst->ops->check(dst, 0) == NULL) {
                                dst_release(dst);
                                sk->sk_rx_dst = NULL;
                        }
                }
                if (unlikely(sk->sk_rx_dst == NULL)) {
                        sk->sk_rx_dst = dst_clone(skb_dst(skb));
                        inet_sk(sk)->rx_dst_ifindex = inet_iif(skb);
                }


IPv6 wants a cookie here, not 0

I wonder why cookie is not stored in dst, and must be stored outside of
it ?

We could then use :
                if (sk->sk_rx_dst) {
                        struct dst_entry *dst = sk->sk_rx_dst;
                        if (dst->ops->check(dst) == NULL) {
                                dst_release(dst);
                                sk->sk_rx_dst = NULL;
                        }
                }


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