netdev - Re: [PATCH net-next] tcp: TCP Fast Open Server

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Message-Id: <20120922.231550.592470091328581312.davem@davemloft.net>
Date:	Sat, 22 Sep 2012 23:15:50 -0400 (EDT)
From:	David Miller <davem@...emloft.net>
To:	ncardwell@...gle.com
Cc:	netdev@...r.kernel.org, edumazet@...gle.com, ycheng@...gle.com,
	hkchu@...gle.com
Subject: Re: [PATCH net-next] tcp: TCP Fast Open Server - record
 retransmits after 3WHS

From: Neal Cardwell <ncardwell@...gle.com>
Date: Sat, 22 Sep 2012 23:03:47 -0400

> When recording the number of SYNACK retransmits for servers using TCP
> Fast Open, fix the code to ensure that we copy over the retransmit
> count from the request_sock after we receive the ACK that completes
> the 3-way handshake.
> 
> The story here is similar to that of SYNACK RTT
> measurements. Previously we were always doing this in
> tcp_v4_syn_recv_sock(). However, for TCP Fast Open connections
> tcp_v4_conn_req_fastopen() calls tcp_v4_syn_recv_sock() at the time we
> receive the SYN. So for TFO we must copy the final SYNACK retransmit
> count in tcp_rcv_state_process().
> 
> Note that copying over the SYNACK retransmit count will give us the
> correct count since, as is mentioned in a comment in
> tcp_retransmit_timer(), before we receive an ACK for our SYN-ACK a TFO
> passive connection does not retransmit anything else (e.g., data or
> FIN segments).
> 
> Signed-off-by: Neal Cardwell <ncardwell@...gle.com>

Applied, thanks Neal.
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