stable inclusion
from stable-v4.19.254
commit 03da610696a32578fc4f986479341ce9d430df08
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I5Q0SQ
CVE: NA

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

[ Upstream commit 5a542133 ]

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

Fixes: 2100c8d2 ("net-tcp: Fast Open base")
Signed-off-by: NKuniyuki Iwashima <kuniyu@amazon.com>
Acked-by: NYuchung Cheng <ycheng@google.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
Signed-off-by: NSasha Levin <sashal@kernel.org>
Signed-off-by: NYongqiang Liu <liuyongqiang13@huawei.com>