netdev - Re: [PATCH next] tcp: fastopen: fix rcv_wup initialization for TFO server on SYN/data

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Date:   Thu, 01 Sep 2016 16:40:35 -0700 (PDT)
From:   David Miller <davem@...emloft.net>
To:     ncardwell@...gle.com
Cc:     netdev@...r.kernel.org, ycheng@...gle.com, edumazet@...gle.com,
        soheil@...gle.com
Subject: Re: [PATCH next] tcp: fastopen: fix rcv_wup initialization for TFO
 server on SYN/data

From: Neal Cardwell <ncardwell@...gle.com>
Date: Tue, 30 Aug 2016 11:55:23 -0400

> Yuchung noticed that on the first TFO server data packet sent after
> the (TFO) handshake, the server echoed the TCP timestamp value in the
> SYN/data instead of the timestamp value in the final ACK of the
> handshake. This problem did not happen on regular opens.
> 
> The tcp_replace_ts_recent() logic that decides whether to remember an
> incoming TS value needs tp->rcv_wup to hold the latest receive
> sequence number that we have ACKed (latest tp->rcv_nxt we have
> ACKed). This commit fixes this issue by ensuring that a TFO server
> properly updates tp->rcv_wup to match tp->rcv_nxt at the time it sends
> a SYN/ACK for the SYN/data.
> 
> Reported-by: Yuchung Cheng <ycheng@...gle.com>
> Signed-off-by: Neal Cardwell <ncardwell@...gle.com>
> Signed-off-by: Yuchung Cheng <ycheng@...gle.com>
> Signed-off-by: Eric Dumazet <edumazet@...gle.com>
> Signed-off-by: Soheil Hassas Yeganeh <soheil@...gle.com>
> Fixes: 168a8f58059a ("tcp: TCP Fast Open Server - main code path")

Applied to 'net', thanks.