netdev - Re: [PATCH net-next] tcp: be less liberal in tsecr received while in SYN

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Message-ID: <CANn89i+3M1bJf=gXMH1zK3LiR-=XMRPe+qR8HNu94o2Xzm4vQQ@mail.gmail.com>
Date: Tue, 25 Feb 2025 11:51:07 +0100
From: Eric Dumazet <edumazet@...gle.com>
To: Matthieu Baerts <matttbe@...nel.org>
Cc: Paolo Abeni <pabeni@...hat.com>, Kuniyuki Iwashima <kuniyu@...zon.com>, 
	Simon Horman <horms@...nel.org>, Florian Westphal <fw@...len.de>, netdev@...r.kernel.org, 
	eric.dumazet@...il.com, Jakub Kicinski <kuba@...nel.org>, 
	Yong-Hao Zou <yonghaoz1994@...il.com>, "David S . Miller" <davem@...emloft.net>, 
	Neal Cardwell <ncardwell@...gle.com>
Subject: Re: [PATCH net-next] tcp: be less liberal in tsecr received while in
 SYN_RECV state

On Tue, Feb 25, 2025 at 11:48 AM Matthieu Baerts <matttbe@...nel.org> wrote:
>
> On 25/02/2025 11:42, Eric Dumazet wrote:
> > On Tue, Feb 25, 2025 at 11:39 AM Eric Dumazet <edumazet@...gle.com> wrote:
> >>
> >
> >>
> >> Yes, this would be it :
> >>
> >> diff --git a/net/ipv4/tcp_timer.c b/net/ipv4/tcp_timer.c
> >> index 728bce01ccd3ddb1f374fa96b86434a415dbe2cb..3555567ba4fb1ccd5c5921e39d11ff08f1d0cafd
> >> 100644
> >> --- a/net/ipv4/tcp_timer.c
> >> +++ b/net/ipv4/tcp_timer.c
> >> @@ -477,8 +477,8 @@ static void tcp_fastopen_synack_timer(struct sock
> >> *sk, struct request_sock *req)
> >>          * regular retransmit because if the child socket has been accepted
> >>          * it's not good to give up too easily.
> >>          */
> >> -       inet_rtx_syn_ack(sk, req);
> >>         req->num_timeout++;
> >> +       inet_rtx_syn_ack(sk, req);
> >>         tcp_update_rto_stats(sk);
> >>         if (!tp->retrans_stamp)
> >>                 tp->retrans_stamp = tcp_time_stamp_ts(tp);
> >
> > Obviously, I need to refine the patch and send a V2 later.
>
> Sorry, I still have the issue with this modification. I also checked
> with the previous patch, just to be sure, but the problem is still there
> as well.

I said "req->num_timeout" is not updated where I thought it was.

Look at all the places were req->num_timeout or req->num_retrans are
set/changed.... this will give you some indications.

Do not worry, I will make sure V2 is fine.

>
> (In the v2, do you mind also removing the underscore from the MIB entry
> name (TcpExtTSECR_Rejected) please? It looks like that's the only MIB
> entry with an underscore.)

ok