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From:   Eric Dumazet <edumazet@google.com>
Date:   Fri, 22 Jan 2021 21:41:27 +0100
Message-ID: <CANn89iLBvwmRbbgw=U3z8k+i_S-ycSf7K-ow4rH5ZQP9CFJuWQ@mail.gmail.com>
Subject: Re: [PATCH net] tcp: make TCP_USER_TIMEOUT accurate for zero window probes
To:     Enke Chen <enkechen2020@gmail.com>
Cc:     "David S. Miller" <davem@davemloft.net>,
        Jakub Kicinski <kuba@kernel.org>,
        Alexey Kuznetsov <kuznet@ms2.inr.ac.ru>,
        Hideaki YOSHIFUJI <yoshfuji@linux-ipv6.org>,
        netdev <netdev@vger.kernel.org>,
        LKML <linux-kernel@vger.kernel.org>,
        Neal Cardwell <ncardwell@google.com>
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On Fri, Jan 22, 2021 at 8:13 PM Enke Chen <enkechen2020@gmail.com> wrote:
>
> From: Enke Chen <enchen@paloaltonetworks.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@paloaltonetworks.com>
> Reviewed-by: Neal Cardwell <ncardwell@google.com>
> ---

SGTM, thanks !

Signed-off-by: Eric Dumazet <edumazet@google.com>