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

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Message-Id: <20240308112504.29099-3-kerneljasonxing@gmail.com>
Date: Fri,  8 Mar 2024 19:25:04 +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 2/2] tcp: annotate a data-race around sysctl_tcp_wmem[0]

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

When reading wmem[0], it could be changed concurrently without
READ_ONCE() protection. So add one annotation here.

Signed-off-by: Jason Xing <kernelxing@...cent.com>
---
 net/ipv4/tcp.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
index c5b83875411a..e3904c006e63 100644
--- a/net/ipv4/tcp.c
+++ b/net/ipv4/tcp.c
@@ -975,7 +975,7 @@ int tcp_wmem_schedule(struct sock *sk, int copy)
 	 * Use whatever is left in sk->sk_forward_alloc and tcp_wmem[0]
 	 * to guarantee some progress.
 	 */
-	left = sock_net(sk)->ipv4.sysctl_tcp_wmem[0] - sk->sk_wmem_queued;
+	left = READ_ONCE(sock_net(sk)->ipv4.sysctl_tcp_wmem[0]) - sk->sk_wmem_queued;
 	if (left > 0)
 		sk_forced_mem_schedule(sk, min(left, copy));
 	return min(copy, sk->sk_forward_alloc);
-- 
2.37.3