From: Eric Dumazet <edumazet@google.com>
Date: Wed, 19 Jul 2023 21:28:47 +0000 (+0000)
Subject: tcp: annotate data-races around tp->tcp_tx_delay
X-Git-Tag: v5.4.251~7
X-Git-Url: http://git.ipfire.org/gitweb/?a=commitdiff_plain;h=8ce44cf35ef6e8ddfc352d73f1eb67bb539f8146;p=thirdparty%2Fkernel%2Fstable.git

tcp: annotate data-races around tp->tcp_tx_delay

[ Upstream commit 348b81b68b13ebd489a3e6a46aa1c384c731c919 ]

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

Fixes: a842fe1425cb ("tcp: add optional per socket transmit delay")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Link: https://lore.kernel.org/r/20230719212857.3943972-2-edumazet@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---

diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
index fdf2ddc4864df..e33abcff56080 100644
--- a/net/ipv4/tcp.c
+++ b/net/ipv4/tcp.c
@@ -3177,7 +3177,7 @@ static int do_tcp_setsockopt(struct sock *sk, int level,
 	case TCP_TX_DELAY:
 		if (val)
 			tcp_enable_tx_delay();
-		tp->tcp_tx_delay = val;
+		WRITE_ONCE(tp->tcp_tx_delay, val);
 		break;
 	default:
 		err = -ENOPROTOOPT;
@@ -3634,7 +3634,7 @@ static int do_tcp_getsockopt(struct sock *sk, int level,
 		break;
 
 	case TCP_TX_DELAY:
-		val = tp->tcp_tx_delay;
+		val = READ_ONCE(tp->tcp_tx_delay);
 		break;
 
 	case TCP_TIMESTAMP: