netdev - Re: TCP fast open using experimental TCP option?

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Message-ID: <1493165636.6453.56.camel@edumazet-glaptop3.roam.corp.google.com>
Date:   Tue, 25 Apr 2017 17:13:56 -0700
From:   Eric Dumazet <eric.dumazet@...il.com>
To:     Tom Herbert <tom@...bertland.com>
Cc:     Linux Kernel Network Developers <netdev@...r.kernel.org>,
        Jerry Chu <hkchu@...gle.com>
Subject: Re: TCP fast open using experimental TCP option?

On Tue, 2017-04-25 at 12:08 -0700, Tom Herbert wrote:
> Looks like TCP fast open was using experimental TCP option at some. Is
> this still needed? Technically this violates usage requirements of
> experimental options. Can this be removed now since there is now an
> assigned option number for TFO?
> 
>                              case TCPOPT_EXP:
>                                 /* Fast Open option shares code 254 using a
>                                  * 16 bits magic number.
>                                  */
>                                 if (opsize >= TCPOLEN_EXP_FASTOPEN_BASE &&
>                                     get_unaligned_be16(ptr) ==
>                                     TCPOPT_FASTOPEN_MAGIC)
>                                         tcp_parse_fastopen_option(opsize -
>                                                 TCPOLEN_EXP_FASTOPEN_BASE,
>                                                 ptr + 2, th->syn, foc, true);
>                                 break;

Hi Tom

Client side was updated in linux-4.1 only two years ago.

We lack counters telling how often the experimental option is used.

RFC6994 ( 5.  Migration to Assigned Options ) guidelines are properly
met.

Not sure why we should hurry ?