stable inclusion
from stable-v4.19.254
commit c7a492db1f7c37c758a66915908677bd8bc5d368
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I5Q0SQ
CVE: NA

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

[ Upstream commit e7d2ef83 ]

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

Fixes: 4f41b1c5 ("tcp: use RACK to detect losses")
Signed-off-by: NKuniyuki Iwashima <kuniyu@amazon.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>