tcp: address problems caused by EDT misshaps

stable inclusion
from linux-4.19.209
commit eb6eeb056c992d20a4d3b4fb7dd05471ba32fea3

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

commit 9efdda4e upstream.

When a qdisc setup including pacing FQ is dismantled and recreated,
some TCP packets are sent earlier than instructed by TCP stack.

TCP can be fooled when ACK comes back, because the following
operation can return a negative value.

    tcp_time_stamp(tp) - tp->rx_opt.rcv_tsecr;

Some paths in TCP stack were not dealing properly with this,
this patch addresses four of them.

Fixes: ab408b6d ("tcp: switch tcp and sch_fq to new earliest departure time model")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Qiumiao Zhang <zhangqiumiao1@huawei.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Conflicts:
  net/ipv4/tcp_timer.c
[yyl: keep implention of
 tcp_clamp_rto_to_user_timeout() and retransmits_timed_out() as mainline]
Reviewed-by: Yue Haibing <yuehaibing@huawei.com>
Acked-by: Jason Yan <yanaijie@huawei.com>
Signed-off-by: Yang Yingliang <yangyingliang@huawei.com>