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| author | Eric Dumazet <edumazet@google.com> | 2019-10-09 12:55:53 -0700 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2020-01-27 14:51:18 +0100 |
| commit | 910699a81fe572b41cc23b46b0616ce7878f5237 (patch) | |
| tree | 5e36555a8ed00f6e00b34fde818a88869cf17332 | |
| parent | 5c1b003d22aba2ff0853f0e775c3cfa7e42522cd (diff) | |
| download | linux-stable-910699a81fe572b41cc23b46b0616ce7878f5237.tar.gz | |
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>
| -rw-r--r-- | net/core/sock.c | 4 |
1 files changed, 2 insertions, 2 deletions
diff --git a/net/core/sock.c b/net/core/sock.c index bbde5f6a7dc9..b9ec14f2c729 100644 --- a/net/core/sock.c +++ b/net/core/sock.c @@ -2179,8 +2179,8 @@ static void sk_leave_memory_pressure(struct sock *sk) } else { unsigned long *memory_pressure = sk->sk_prot->memory_pressure; - if (memory_pressure && *memory_pressure) - *memory_pressure = 0; + if (memory_pressure && READ_ONCE(*memory_pressure)) + WRITE_ONCE(*memory_pressure, 0); } } |