netdev - Re: [PATCH net] tcp: fix tcpi_segs_in after connection establishment

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Message-Id: <20160307.154743.670423088656600403.davem@davemloft.net>
Date:	Mon, 07 Mar 2016 15:47:43 -0500 (EST)
From:	David Miller <davem@...emloft.net>
To:	eric.dumazet@...il.com
Cc:	kafai@...com, netdev@...r.kernel.org, kernel-team@...com,
	rapier@....edu, edumazet@...gle.com, mleitner@...hat.com,
	ncardwell@...gle.com, ycheng@...gle.com
Subject: Re: [PATCH net] tcp: fix tcpi_segs_in after connection
 establishment

From: Eric Dumazet <eric.dumazet@...il.com>
Date: Sun, 06 Mar 2016 09:29:21 -0800

> From: Eric Dumazet <edumazet@...gle.com>
> 
> If final packet (ACK) of 3WHS is lost, it appears we do not properly
> account the following incoming segment into tcpi_segs_in
> 
> While we are at it, starts segs_in with one, to count the SYN packet.
> 
> We do not yet count number of SYN we received for a request sock, we
> might add this someday.
> 
> packetdrill script showing proper behavior after fix :
> 
> // Tests tcpi_segs_in when 3rd packet (ACK) of 3WHS is lost
> 0.000 socket(..., SOCK_STREAM, IPPROTO_TCP) = 3
>    +0 setsockopt(3, SOL_SOCKET, SO_REUSEADDR, [1], 4) = 0
>    +0 bind(3, ..., ...) = 0
>    +0 listen(3, 1) = 0
> 
>    +0 < S 0:0(0) win 32792 <mss 1000,sackOK,nop,nop>
>    +0 > S. 0:0(0) ack 1 <mss 1460,nop,nop,sackOK>
> +.020 < P. 1:1001(1000) ack 1 win 32792
> 
>    +0 accept(3, ..., ...) = 4
> 
> +.000 %{ assert tcpi_segs_in == 2, 'tcpi_segs_in=%d' % tcpi_segs_in }%
> 
> Fixes: 2efd055c53c06 ("tcp: add tcpi_segs_in and tcpi_segs_out to tcp_info")
> Signed-off-by: Eric Dumazet <edumazet@...gle.com>

Applied and queued up for -stable, thanks.