tcp: adjust rto_base in retransmits_timed_out()

mainline inclusion
from mainline-v5.4-rc2
commit 3256a2d6
category: bugfix
bugzilla:
https://gitee.com/openeuler/kernel/issues/I4AFRJ?from=project-issue


CVE: NA

------------------------------------------------------------

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: a41e8a88 ("tcp: better handle TCP_USER_TIMEOUT in SYN_SENT state")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Yuchung Cheng <ycheng@google.com>
Cc: Marek Majkowski <marek@cloudflare.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Conflicts:
        net/ipv4/tcp_timer.c
Signed-off-by: Jiazhenyuan <jiazhenyuan@uniontech.com> #openEuler_contributor
Signed-off-by: Laibin Qiu <qiulaibin@huawei.com>
Reviewed-by: Wei Yongjun <weiyongjun1@huawei.com>
Signed-off-by: Yang Yingliang <yangyingliang@huawei.com>