diff options
| author | Eric Dumazet <edumazet@google.com> | 2019-10-09 12:55:53 -0700 |
|---|---|---|
| committer | Jakub Kicinski <jakub.kicinski@netronome.com> | 2019-10-09 21:30:22 -0700 |
| commit | 503978aca46124cd714703e180b9c8292ba50ba7 (patch) | |
| tree | f50bafcd6d959fb284425e2ac830b8f73c5dbbb7 /net | |
| parent | 4ffdd22e49f47db543906d75453a0048a53071ab (diff) | |
net: avoid possible false sharing in sk_leave_memory_pressure()
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>
Diffstat (limited to 'net')
| -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 fac2b4d80de5..50647a10fdb7 100644 --- a/net/core/sock.c +++ b/net/core/sock.c @@ -2334,8 +2334,8 @@ 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); } } |