netdev - RE: [PATCH net-next 1/1] net: tcp: Define the TCP_MAX

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Date:   Mon, 3 Apr 2017 21:26:10 +0800
From:   "Gao Feng" <gfree.wind@...mail.com>
To:     "'Neal Cardwell'" <ncardwell@...gle.com>
Cc:     "'David Miller'" <davem@...emloft.net>,
        "'Alexey Kuznetsov'" <kuznet@....inr.ac.ru>,
        "'James Morris'" <jmorris@...ei.org>,
        "'Patrick McHardy'" <kaber@...sh.net>,
        "'Netdev'" <netdev@...r.kernel.org>, "'Gao Feng'" <fgao@...ai8.com>
Subject: RE: [PATCH net-next 1/1] net: tcp: Define the TCP_MAX_WSCALE instead of literal number 14

> -----Original Message-----
> From: Neal Cardwell [mailto:ncardwell@...gle.com]
> Sent: Monday, April 3, 2017 2:59 AM
> To: gfree.wind@...mail.com
> Cc: David Miller <davem@...emloft.net>; Alexey Kuznetsov
> <kuznet@....inr.ac.ru>; James Morris <jmorris@...ei.org>; Patrick McHardy
> <kaber@...sh.net>; Netdev <netdev@...r.kernel.org>; Gao Feng
> <fgao@...ai8.com>
> Subject: Re: [PATCH net-next 1/1] net: tcp: Define the TCP_MAX_WSCALE
> instead of literal number 14
> 
> On Sat, Apr 1, 2017 at 12:14 AM,  <gfree.wind@...mail.com> wrote:
> > From: Gao Feng <fgao@...ai8.com>
> >
> > Define one new macro TCP_MAX_WSCALE instead of literal number '14',
> > and use U16_MAX instead of 65535 as the max value of TCP window.
> > There is another minor change, use rounddown(space, mss) instead of
> > (space / mss) * mss;
> >
> > Signed-off-by: Gao Feng <fgao@...ai8.com>
> > ---
> 
> Looks OK to me.
> 
> IMHO this is a nice direction, since there is a proposal to increase the maximum
> shift factor from 14 to 15:
>   https://tools.ietf.org/html/draft-nishida-tcpm-maxwin-03

Do you mean enlarge the wscale to 15 now ?

> 
> Though there are a few spots where a literal 14 appears:
> 
> tcp_input.c:3763:  net_info_ratelimited("%s: Illegal window scaling
> value %d >14 received\n",
> 
> tcp_output.c:238:                * See RFC1323 for an explanation of
> the limit to 14

Ok, I will update these two spots.

Regards
Feng
> 
> 
> neal