tcp: annotate data-races around tp->notsent_lowat

stable inclusion
from stable-v4.19.291
commit 73e2b8a15ea42ccb2d4bcd26e55d4092a1a8e4e5
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I7ZELT


CVE: NA

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

[ Upstream commit 1aeb87bc ]

tp->notsent_lowat can be read locklessly from do_tcp_getsockopt()
and tcp_poll().

Fixes: c9bee3b7 ("tcp: TCP_NOTSENT_LOWAT socket option")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Link: https://lore.kernel.org/r/20230719212857.3943972-10-edumazet@google.com


Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Yongqiang Liu <liuyongqiang13@huawei.com>