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@google.com>
Link: https://lore.kernel.org/r/20230719212857.3943972-2-edumazet@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
index e03e08745308189c9d64509c2cff94da56c86a0c..bd6400e1ae9f8ae595bbe759ff3dfb1bd02765e2 100644 (file)
--- 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: