tree 5e36555a8ed00f6e00b34fde818a88869cf17332
parent 5c1b003d22aba2ff0853f0e775c3cfa7e42522cd
author Eric Dumazet <edumazet@google.com> 1570650953 -0700
committer Greg Kroah-Hartman <gregkh@linuxfoundation.org> 1580133078 +0100

net: avoid possible false sharing in sk_leave_memory_pressure()

[ Upstream commit 503978aca46124cd714703e180b9c8292ba50ba7 ]

As mentioned in https://github.com/google/ktsan/wiki/READ_ONCE-and-WRITE_ONCE#it-may-improve-performance
a C compiler can legally transform :

if (memory_pressure && *memory_pressure)
        *memory_pressure = 0;

to :

if (memory_pressure)
        *memory_pressure = 0;

Fixes: 0604475119de ("tcp: add TCPMemoryPressuresChrono counter")
Fixes: 180d8cd942ce ("foundations of per-cgroup memory pressure controlling.")
Fixes: 3ab224be6d69 ("[NET] CORE: Introducing new memory accounting interface.")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>