tcp: annotate lockless access to tcp_memory_pressure

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>

1 files changed, 2 insertions, 2 deletions

diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
index f98a1882e537..888c92b63f5a 100644
--- a/net/ipv4/tcp.c
+++ b/net/ipv4/tcp.c
@@ -326,7 +326,7 @@ void tcp_enter_memory_pressure(struct sock *sk)
 {
         unsigned long val;
 
-        if (tcp_memory_pressure)
+        if (READ_ONCE(tcp_memory_pressure))
                 return;
         val = jiffies;
 
@@ -341,7 +341,7 @@ 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)