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authorEric Dumazet <edumazet@google.com>2019-10-10 01:10:15 +0300
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2020-01-27 16:51:18 +0300
commita92c895e22b738454f06651f3aa4d8f441157f18 (patch)
tree32ea93a9c2aba22f37148e89ddfa35a017ff6d43
parentb0fb910bfdf469fa5016e939c778cfb566be2e33 (diff)
downloadlinux-a92c895e22b738454f06651f3aa4d8f441157f18.tar.xz
tcp: annotate lockless access to tcp_memory_pressure
[ Upstream commit 1f142c17d19a5618d5a633195a46f2c8be9bf232 ] tcp_memory_pressure is read without holding any lock, and its value could be changed on other cpus. Use READ_ONCE() to annotate these lockless reads. The write side is already using atomic ops. Fixes: b8da51ebb1aa ("tcp: introduce tcp_under_memory_pressure()") 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--include/net/tcp.h2
-rw-r--r--net/ipv4/tcp.c4
2 files changed, 3 insertions, 3 deletions
diff --git a/include/net/tcp.h b/include/net/tcp.h
index ac4ffe8013d8..918bfd0d7d1f 100644
--- a/include/net/tcp.h
+++ b/include/net/tcp.h
@@ -261,7 +261,7 @@ static inline bool tcp_under_memory_pressure(const struct sock *sk)
mem_cgroup_under_socket_pressure(sk->sk_memcg))
return true;
- return tcp_memory_pressure;
+ return READ_ONCE(tcp_memory_pressure);
}
/*
* The next routines deal with comparing 32 bit unsigned ints
diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
index cd8a92e7a39e..af9361eba64a 100644
--- a/net/ipv4/tcp.c
+++ b/net/ipv4/tcp.c
@@ -325,7 +325,7 @@ void tcp_enter_memory_pressure(struct sock *sk)
{
unsigned long val;
- if (tcp_memory_pressure)
+ if (READ_ONCE(tcp_memory_pressure))
return;
val = jiffies;
@@ -340,7 +340,7 @@ void tcp_leave_memory_pressure(struct sock *sk)
{
unsigned long val;
- if (!tcp_memory_pressure)
+ if (!READ_ONCE(tcp_memory_pressure))
return;
val = xchg(&tcp_memory_pressure, 0);
if (val)