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authorEric Dumazet <edumazet@google.com>2019-10-09 12:55:53 -0700
committerJakub Kicinski <jakub.kicinski@netronome.com>2019-10-09 21:30:22 -0700
commit503978aca46124cd714703e180b9c8292ba50ba7 (patch)
treef50bafcd6d959fb284425e2ac830b8f73c5dbbb7 /net
parent4ffdd22e49f47db543906d75453a0048a53071ab (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.c4
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);
}
}