net: Fix a data-race around sysctl_net_busy_poll.

While reading sysctl_net_busy_poll, it can be changed concurrently.
Thus, we need to add READ_ONCE() to its reader.

Fixes: 82c99366c08d ("net: add low latency socket poll")
Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/include/net/busy_poll.h b/include/net/busy_poll.h
index c4898fcbf923bf01f14c6bcc694eb036d75d7195..f90f0021f5f2dd4932c564ce8b8a7333093456c5 100644 (file)
--- a/include/net/busy_poll.h
+++ b/include/net/busy_poll.h
@@ -33,7 +33,7 @@ extern unsigned int sysctl_net_busy_poll __read_mostly;
 
 static inline bool net_busy_loop_on(void)
 {
-       return sysctl_net_busy_poll;
+       return READ_ONCE(sysctl_net_busy_poll);
 }
 
 static inline bool sk_can_busy_loop(const struct sock *sk)