tcp: Fix a data-race around sysctl_tcp_early_retrans.

stable inclusion
from stable-v5.10.134
commit 11e8b013d16e5db63f8f76acceb5b86964098aaa
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I5ZVR7

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=11e8b013d16e5db63f8f76acceb5b86964098aaa



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[ Upstream commit 52e65865 ]

While reading sysctl_tcp_early_retrans, it can be changed concurrently.
Thus, we need to add READ_ONCE() to its reader.

Fixes: eed530b6 ("tcp: early retransmit")
Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Zheng Zengkai <zhengzengkai@huawei.com>
Reviewed-by: Wei Li <liwei391@huawei.com>