netdev - [PATCH net 10/11] tcp: annotate data-races around icsk->icsk_user

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Date: Wed, 19 Jul 2023 21:28:56 +0000
From: Eric Dumazet <edumazet@...gle.com>
To: "David S . Miller" <davem@...emloft.net>, Jakub Kicinski <kuba@...nel.org>, 
	Paolo Abeni <pabeni@...hat.com>
Cc: netdev@...r.kernel.org, eric.dumazet@...il.com, 
	Eric Dumazet <edumazet@...gle.com>
Subject: [PATCH net 10/11] tcp: annotate data-races around icsk->icsk_user_timeout

This field can be read locklessly from do_tcp_getsockopt()

Fixes: dca43c75e7e5 ("tcp: Add TCP_USER_TIMEOUT socket option.")
Signed-off-by: Eric Dumazet <edumazet@...gle.com>
---
 net/ipv4/tcp.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
index 2b2241e9b492726562a6b5055cf8c168e5fed799..3e137e9a18f552a02d8c74e1af34ba2356e4d8ed 100644
--- a/net/ipv4/tcp.c
+++ b/net/ipv4/tcp.c
@@ -3300,7 +3300,7 @@ EXPORT_SYMBOL(tcp_sock_set_syncnt);
 void tcp_sock_set_user_timeout(struct sock *sk, u32 val)
 {
 	lock_sock(sk);
-	inet_csk(sk)->icsk_user_timeout = val;
+	WRITE_ONCE(inet_csk(sk)->icsk_user_timeout, val);
 	release_sock(sk);
 }
 EXPORT_SYMBOL(tcp_sock_set_user_timeout);
@@ -3620,7 +3620,7 @@ int do_tcp_setsockopt(struct sock *sk, int level, int optname,
 		if (val < 0)
 			err = -EINVAL;
 		else
-			icsk->icsk_user_timeout = val;
+			WRITE_ONCE(icsk->icsk_user_timeout, val);
 		break;
 
 	case TCP_FASTOPEN:
@@ -4141,7 +4141,7 @@ int do_tcp_getsockopt(struct sock *sk, int level,
 		break;
 
 	case TCP_USER_TIMEOUT:
-		val = icsk->icsk_user_timeout;
+		val = READ_ONCE(icsk->icsk_user_timeout);
 		break;
 
 	case TCP_FASTOPEN:
-- 
2.41.0.255.g8b1d071c50-goog