Commit 503978ac authored by Eric Dumazet's avatar Eric Dumazet Committed by Jakub Kicinski

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: 06044751 ("tcp: add TCPMemoryPressuresChrono counter")
Fixes: 180d8cd9 ("foundations of per-cgroup memory pressure controlling.")
Fixes: 3ab224be ("[NET] CORE: Introducing new memory accounting interface.")
Signed-off-by: default avatarEric Dumazet <edumazet@google.com>
Signed-off-by: default avatarJakub Kicinski <jakub.kicinski@netronome.com>
parent 4ffdd22e
...@@ -2334,8 +2334,8 @@ static void sk_leave_memory_pressure(struct sock *sk) ...@@ -2334,8 +2334,8 @@ static void sk_leave_memory_pressure(struct sock *sk)
} else { } else {
unsigned long *memory_pressure = sk->sk_prot->memory_pressure; unsigned long *memory_pressure = sk->sk_prot->memory_pressure;
if (memory_pressure && *memory_pressure) if (memory_pressure && READ_ONCE(*memory_pressure))
*memory_pressure = 0; WRITE_ONCE(*memory_pressure, 0);
} }
} }
......
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