netdev - Re: [PATCH net] tcp: don't include Fast Open option in SYN-ACK on pure SYN-data

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Message-ID: <CADVnQy=aOGWn2CA07KYLkbcsLB6_8-bncnLaJ+BNcQ516b0c8g@mail.gmail.com>
Date:	Thu, 5 Feb 2015 19:58:27 -0500
From:	Neal Cardwell <ncardwell@...gle.com>
To:	Yuchung Cheng <ycheng@...gle.com>
Cc:	David Miller <davem@...emloft.net>,
	Eric Dumazet <edumazet@...gle.com>,
	Netdev <netdev@...r.kernel.org>
Subject: Re: [PATCH net] tcp: don't include Fast Open option in SYN-ACK on
 pure SYN-data

On Thu, Feb 5, 2015 at 7:44 PM, Yuchung Cheng <ycheng@...gle.com> wrote:
> If a server has enabled Fast Open and it receives a pure SYN-data
> packet (without a Fast Open option), it won't accept the data but it
> incorrectly returns a SYN-ACK with a Fast Open cookie and also
> increments the SNMP stat LINUX_MIB_TCPFASTOPENPASSIVEFAIL.
>
> This patch makes the server include a Fast Open cookie in SYN-ACK
> only if the SYN has some Fast Open option (i.e., when client
> requests or presents a cookie).
>
> Signed-off-by: Yuchung Cheng <ycheng@...gle.com>
> ---
>  net/ipv4/tcp_fastopen.c | 13 ++++++++-----
>  1 file changed, 8 insertions(+), 5 deletions(-)

Acked-by: Neal Cardwell <ncardwell@...gle.com>

neal
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