From: Kuniyuki Iwashima <kuniyu@amazon.com>
Date: Tue, 23 Aug 2022 17:46:51 +0000 (-0700)
Subject: net: Fix a data-race around sysctl_net_busy_poll.
X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=4e12829fd3b9fd428424e865fbb90c093080cb4d;p=linux.git

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 40296ed976a97..3459a04a3d61c 100644
--- 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)