netdev - Re: [PATCH net] tcp: adjust rto_base in retransmits_timed

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Message-Id: <20191001.214135.98815209147906561.davem@davemloft.net>
Date:   Tue, 01 Oct 2019 21:41:35 -0400 (EDT)
From:   David Miller <davem@...emloft.net>
To:     edumazet@...gle.com
Cc:     netdev@...r.kernel.org, ncardwell@...gle.com,
        eric.dumazet@...il.com, ycheng@...gle.com, marek@...udflare.com
Subject: Re: [PATCH net] tcp: adjust rto_base in retransmits_timed_out()

From: Eric Dumazet <edumazet@...gle.com>
Date: Mon, 30 Sep 2019 15:44:44 -0700

> The cited commit exposed an old retransmits_timed_out() bug
> which assumed it could call tcp_model_timeout() with
> TCP_RTO_MIN as rto_base for all states.
> 
> But flows in SYN_SENT or SYN_RECV state uses a different
> RTO base (1 sec instead of 200 ms, unless BPF choses
> another value)
> 
> This caused a reduction of SYN retransmits from 6 to 4 with
> the default /proc/sys/net/ipv4/tcp_syn_retries value.
> 
> Fixes: a41e8a88b06e ("tcp: better handle TCP_USER_TIMEOUT in SYN_SENT state")
> Signed-off-by: Eric Dumazet <edumazet@...gle.com>

Applied and queued up for -stable.