netdev - [PATCH net 01/11] tcp: annotate data-races around tp->tcp_tx

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Message-ID: <20230719212857.3943972-2-edumazet@google.com>
Date: Wed, 19 Jul 2023 21:28:47 +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 01/11] tcp: annotate data-races around tp->tcp_tx_delay

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@...gle.com>
---
 net/ipv4/tcp.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
index e03e08745308189c9d64509c2cff94da56c86a0c..bd6400e1ae9f8ae595bbe759ff3dfb1bd02765e2 100644
--- a/net/ipv4/tcp.c
+++ b/net/ipv4/tcp.c
@@ -3674,7 +3674,7 @@ int do_tcp_setsockopt(struct sock *sk, int level, int optname,
 	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;
@@ -4154,7 +4154,7 @@ 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:
-- 
2.41.0.255.g8b1d071c50-goog