net: Fix a data-race around sysctl_net_busy_poll.

[ Upstream commit c42b7cddea47503411bfb5f2f93a4154aaffa2d9 ]

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

Fixes: 060212928670 ("net: add low latency socket poll")
Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/include/net/busy_poll.h b/include/net/busy_poll.h
index 2fbeb1313c0f4f78ac82ddf6c18d1016a901f99a..e522187cb69358d666831f2b03f6cfae5a9229fb 100644 (file)
--- a/include/net/busy_poll.h
+++ b/include/net/busy_poll.h
@@ -39,7 +39,7 @@ 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 u64 busy_loop_us_clock(void)