tcp: annotate data-races around rskq_defer_accept

do_tcp_getsockopt() reads rskq_defer_accept while another cpu
might change its value.

Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Link: https://lore.kernel.org/r/20230719212857.3943972-9-edumazet@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
index 2cf129a..5beec71 100644 (file)
--- a/net/ipv4/tcp.c
+++ b/net/ipv4/tcp.c
@@ -3594,9 +3594,9 @@ int do_tcp_setsockopt(struct sock *sk, int level, int optname,
 
        case TCP_DEFER_ACCEPT:
                /* Translate value in seconds to number of retransmits */
-               icsk->icsk_accept_queue.rskq_defer_accept =
-                       secs_to_retrans(val, TCP_TIMEOUT_INIT / HZ,
-                                       TCP_RTO_MAX / HZ);
+               WRITE_ONCE(icsk->icsk_accept_queue.rskq_defer_accept,
+                          secs_to_retrans(val, TCP_TIMEOUT_INIT / HZ,
+                                          TCP_RTO_MAX / HZ));
                break;
 
        case TCP_WINDOW_CLAMP:
@@ -4002,8 +4002,9 @@ int do_tcp_getsockopt(struct sock *sk, int level,
                        val = (val ? : READ_ONCE(net->ipv4.sysctl_tcp_fin_timeout)) / HZ;
                break;
        case TCP_DEFER_ACCEPT:
-               val = retrans_to_secs(icsk->icsk_accept_queue.rskq_defer_accept,
-                                     TCP_TIMEOUT_INIT / HZ, TCP_RTO_MAX / HZ);
+               val = READ_ONCE(icsk->icsk_accept_queue.rskq_defer_accept);
+               val = retrans_to_secs(val, TCP_TIMEOUT_INIT / HZ,
+                                     TCP_RTO_MAX / HZ);
                break;
        case TCP_WINDOW_CLAMP:
                val = tp->window_clamp;