netdev - [PATCH net 07/11] tcp: annotate data-races around tp->linger2

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Message-ID: <20230719212857.3943972-8-edumazet@google.com>
Date: Wed, 19 Jul 2023 21:28:53 +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 07/11] tcp: annotate data-races around tp->linger2

do_tcp_getsockopt() reads tp->linger2 while another cpu
might change its value.

Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Signed-off-by: Eric Dumazet <edumazet@...gle.com>
---
 net/ipv4/tcp.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
index 9f74ac16f1c1e53353bd14c6a04e1fa9e3de0c15..2cf129a0c00bfef813e1f1e12cb247ef8107fa88 100644
--- a/net/ipv4/tcp.c
+++ b/net/ipv4/tcp.c
@@ -3585,11 +3585,11 @@ int do_tcp_setsockopt(struct sock *sk, int level, int optname,
 
 	case TCP_LINGER2:
 		if (val < 0)
-			tp->linger2 = -1;
+			WRITE_ONCE(tp->linger2, -1);
 		else if (val > TCP_FIN_TIMEOUT_MAX / HZ)
-			tp->linger2 = TCP_FIN_TIMEOUT_MAX;
+			WRITE_ONCE(tp->linger2, TCP_FIN_TIMEOUT_MAX);
 		else
-			tp->linger2 = val * HZ;
+			WRITE_ONCE(tp->linger2, val * HZ);
 		break;
 
 	case TCP_DEFER_ACCEPT:
@@ -3997,7 +3997,7 @@ int do_tcp_getsockopt(struct sock *sk, int level,
 			READ_ONCE(net->ipv4.sysctl_tcp_syn_retries);
 		break;
 	case TCP_LINGER2:
-		val = tp->linger2;
+		val = READ_ONCE(tp->linger2);
 		if (val >= 0)
 			val = (val ? : READ_ONCE(net->ipv4.sysctl_tcp_fin_timeout)) / HZ;
 		break;
-- 
2.41.0.255.g8b1d071c50-goog