From: Eric Dumazet <eduma...@google.com>
Date: Thu, 26 Sep 2019 15:42:51 -0700
> Yuchung Cheng and Marek Majkowski independently reported a weird
> behavior of TCP_USER_TIMEOUT option when used at connect() time.
>
> When the TCP_USER_TIMEOUT is reached, tcp_write_timeout()
> believes the flow should live, and the following condition
> in tcp_clamp_rto_to_user_timeout() programs one jiffie timers :
>
> remaining = icsk->icsk_user_timeout - elapsed;
> if (remaining <= 0)
> return 1; /* user timeout has passed; fire ASAP */
>
> This silly situation ends when the max syn rtx count is reached.
>
> This patch makes sure we honor both TCP_SYNCNT and TCP_USER_TIMEOUT,
> avoiding these spurious SYN packets.
>
> Fixes: b701a99e431d ("tcp: Add tcp_clamp_rto_to_user_timeout() helper to
> improve accuracy")
> Signed-off-by: Eric Dumazet <eduma...@google.com>
> Reported-by: Yuchung Cheng <ych...@google.com>
> Reported-by: Marek Majkowski <ma...@cloudflare.com>
> Cc: Jon Maxwell <jmaxwel...@gmail.com>
> Link: https://marc.info/?l=linux-netdev&m=156940118307949&w=2
Applied and queued up for -stable.
