netdev - [PATCH net-next 1/2] mptcp: annotate a data-race around sysctl_tcp

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Message-Id: <20240308112504.29099-2-kerneljasonxing@gmail.com>
Date: Fri,  8 Mar 2024 19:25:03 +0800
From: Jason Xing <kerneljasonxing@...il.com>
To: edumazet@...gle.com,
	dsahern@...nel.org,
	matttbe@...nel.org,
	martineau@...nel.org,
	geliang@...nel.org,
	kuba@...nel.org,
	pabeni@...hat.com,
	davem@...emloft.net
Cc: mptcp@...ts.linux.dev,
	netdev@...r.kernel.org,
	kerneljasonxing@...il.com,
	Jason Xing <kernelxing@...cent.com>
Subject: [PATCH net-next 1/2] mptcp: annotate a data-race around sysctl_tcp_wmem[0]

From: Jason Xing <kernelxing@...cent.com>

It's possible that writer and the reader can manipulate the same
sysctl knob concurrently. Using READ_ONCE() to prevent reading
an old value.

Signed-off-by: Jason Xing <kernelxing@...cent.com>
---
 net/mptcp/protocol.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/mptcp/protocol.h b/net/mptcp/protocol.h
index f16edef6026a..a10ebf3ee10a 100644
--- a/net/mptcp/protocol.h
+++ b/net/mptcp/protocol.h
@@ -850,7 +850,7 @@ static inline void __mptcp_sync_sndbuf(struct sock *sk)
 	if (sk->sk_userlocks & SOCK_SNDBUF_LOCK)
 		return;
 
-	new_sndbuf = sock_net(sk)->ipv4.sysctl_tcp_wmem[0];
+	new_sndbuf = READ_ONCE(sock_net(sk)->ipv4.sysctl_tcp_wmem[0]);
 	mptcp_for_each_subflow(mptcp_sk(sk), subflow) {
 		ssk_sndbuf =  READ_ONCE(mptcp_subflow_tcp_sock(subflow)->sk_sndbuf);
 
-- 
2.37.3