netdev - Re: [PATCH net] tcp: make TCP_USER_TIMEOUT accurate for zero window probes

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Message-ID: <20210123022823.GA100578@localhost.localdomain>
Date:   Fri, 22 Jan 2021 18:28:23 -0800
From:   Enke Chen <enkechen2020@...il.com>
To:     Jakub Kicinski <kuba@...nel.org>
Cc:     Eric Dumazet <edumazet@...gle.com>,
        "David S. Miller" <davem@...emloft.net>,
        Alexey Kuznetsov <kuznet@....inr.ac.ru>,
        Hideaki YOSHIFUJI <yoshfuji@...ux-ipv6.org>,
        netdev@...r.kernel.org, linux-kernel@...r.kernel.org,
        Neal Cardwell <ncardwell@...gle.com>, enkechen2020@...il.com
Subject: Re: [PATCH net] tcp: make TCP_USER_TIMEOUT accurate for zero window
 probes

Hi, Jakub:

In terms of backporting, this patch should go together with:

    9d9b1ee0b2d1 tcp: fix TCP_USER_TIMEOUT with zero window

Thanks.  -- Enke

On Fri, Jan 22, 2021 at 05:43:25PM -0800, Jakub Kicinski wrote:
> On Fri, 22 Jan 2021 11:13:06 -0800 Enke Chen wrote:
> > From: Enke Chen <enchen@...oaltonetworks.com>
> > 
> > The TCP_USER_TIMEOUT is checked by the 0-window probe timer. As the
> > timer has backoff with a max interval of about two minutes, the
> > actual timeout for TCP_USER_TIMEOUT can be off by up to two minutes.
> > 
> > In this patch the TCP_USER_TIMEOUT is made more accurate by taking it
> > into account when computing the timer value for the 0-window probes.
> > 
> > This patch is similar to the one that made TCP_USER_TIMEOUT accurate for
> > RTOs in commit b701a99e431d ("tcp: Add tcp_clamp_rto_to_user_timeout()
> > helper to improve accuracy").
> > 
> > Signed-off-by: Enke Chen <enchen@...oaltonetworks.com>
> > Reviewed-by: Neal Cardwell <ncardwell@...gle.com>
> 
> This is targeting net, any guidance on Fixes / backporting?