tcp: annotate data-races around icsk->icsk_retransmits

icsk->icsk_retransmits is read locklessly from inet_sk_diag_fill(),
tcp_get_timestamping_opt_stats, get_tcp4_sock() and get_tcp6_sock().

Add corresponding READ_ONCE()/WRITE_ONCE() annotations.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: Neal Cardwell <ncardwell@google.com>
Link: https://patch.msgid.link/20250822091727.835869-2-edumazet@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

diff --git a/net/ipv4/inet_diag.c b/net/ipv4/inet_diag.c
index 2fa53b16fe7788eed9796c8476157a77eced096c..35c1579e5bd4cef4a8c44d03ed1af16fe1735ac0 100644 (file)
--- a/net/ipv4/inet_diag.c
+++ b/net/ipv4/inet_diag.c
@@ -313,7 +313,7 @@ int inet_sk_diag_fill(struct sock *sk, struct inet_connection_sock *icsk,
            icsk_pending == ICSK_TIME_REO_TIMEOUT ||
            icsk_pending == ICSK_TIME_LOSS_PROBE) {
                r->idiag_timer = 1;
-               r->idiag_retrans = icsk->icsk_retransmits;
+               r->idiag_retrans = READ_ONCE(icsk->icsk_retransmits);
                r->idiag_expires =
                        jiffies_delta_to_msecs(icsk_timeout(icsk) - jiffies);
        } else if (icsk_pending == ICSK_TIME_PROBE0) {

diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
index 99232903b03c99d263cce59314fd369cfd33af6f..4728801d06a7a1dabfaab2ce27a6dcfa36ffce7f 100644 (file)
--- a/net/ipv4/tcp.c
+++ b/net/ipv4/tcp.c
@@ -4346,7 +4346,8 @@ struct sk_buff *tcp_get_timestamping_opt_stats(const struct sock *sk,
        nla_put_u32(stats, TCP_NLA_REORDERING, tp->reordering);
        nla_put_u32(stats, TCP_NLA_MIN_RTT, tcp_min_rtt(tp));
 
-       nla_put_u8(stats, TCP_NLA_RECUR_RETRANS, inet_csk(sk)->icsk_retransmits);
+       nla_put_u8(stats, TCP_NLA_RECUR_RETRANS,
+                  READ_ONCE(inet_csk(sk)->icsk_retransmits));
        nla_put_u8(stats, TCP_NLA_DELIVERY_RATE_APP_LMT, !!tp->rate_app_limited);
        nla_put_u32(stats, TCP_NLA_SND_SSTHRESH, tp->snd_ssthresh);
        nla_put_u32(stats, TCP_NLA_DELIVERED, tp->delivered);

diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
index 7b537978dfe6b436c723815f1ce64f05f9c1ae61..3baf3bef0d8328bc21150d6be45b32179da38f90 100644 (file)
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -2569,7 +2569,7 @@ static bool tcp_try_undo_loss(struct sock *sk, bool frto_undo)
                if (frto_undo)
                        NET_INC_STATS(sock_net(sk),
                                        LINUX_MIB_TCPSPURIOUSRTOS);
-               inet_csk(sk)->icsk_retransmits = 0;
+               WRITE_ONCE(inet_csk(sk)->icsk_retransmits, 0);
                if (tcp_is_non_sack_preventing_reopen(sk))
                        return true;
                if (frto_undo || tcp_is_sack(tp)) {
@@ -3851,7 +3851,7 @@ static int tcp_ack(struct sock *sk, const struct sk_buff *skb, int flag)
 
        if (after(ack, prior_snd_una)) {
                flag |= FLAG_SND_UNA_ADVANCED;
-               icsk->icsk_retransmits = 0;
+               WRITE_ONCE(icsk->icsk_retransmits, 0);
 
 #if IS_ENABLED(CONFIG_TLS_DEVICE)
                if (static_branch_unlikely(&clean_acked_data_enabled.key))
@@ -6636,7 +6636,7 @@ static void tcp_rcv_synrecv_state_fastopen(struct sock *sk)
                tcp_try_undo_recovery(sk);
 
        tcp_update_rto_time(tp);
-       inet_csk(sk)->icsk_retransmits = 0;
+       WRITE_ONCE(inet_csk(sk)->icsk_retransmits, 0);
        /* In tcp_fastopen_synack_timer() on the first SYNACK RTO we set
         * retrans_stamp but don't enter CA_Loss, so in case that happened we
         * need to zero retrans_stamp here to prevent spurious

diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c
index 84d3d556ed8062d07fe7019bc0dadd90d3b80d96..5d549dfd4e601eedb7c5cc3f3e503a5bef7ed4a4 100644 (file)
--- a/net/ipv4/tcp_ipv4.c
+++ b/net/ipv4/tcp_ipv4.c
@@ -2958,7 +2958,7 @@ static void get_tcp4_sock(struct sock *sk, struct seq_file *f, int i)
                rx_queue,
                timer_active,
                jiffies_delta_to_clock_t(timer_expires - jiffies),
-               icsk->icsk_retransmits,
+               READ_ONCE(icsk->icsk_retransmits),
                from_kuid_munged(seq_user_ns(f), sk_uid(sk)),
                icsk->icsk_probes_out,
                sock_i_ino(sk),

diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c
index 86892c8672ed49a49b85530b648d695ed171a3c8..72969c27eaaae4123dbc30bd8709a30be14d6830 100644 (file)
--- a/net/ipv4/tcp_output.c
+++ b/net/ipv4/tcp_output.c
@@ -3956,7 +3956,7 @@ static void tcp_connect_init(struct sock *sk)
        WRITE_ONCE(tp->copied_seq, tp->rcv_nxt);
 
        inet_csk(sk)->icsk_rto = tcp_timeout_init(sk);
-       inet_csk(sk)->icsk_retransmits = 0;
+       WRITE_ONCE(inet_csk(sk)->icsk_retransmits, 0);
        tcp_clear_retrans(tp);
 }
 

diff --git a/net/ipv4/tcp_timer.c b/net/ipv4/tcp_timer.c
index a207877270fbdef6f86f61093aa476b6cd6f8706..8b11ab4cc9524f0e0066f474044a4c585115ec29 100644 (file)
--- a/net/ipv4/tcp_timer.c
+++ b/net/ipv4/tcp_timer.c
@@ -444,7 +444,7 @@ static void tcp_update_rto_stats(struct sock *sk)
                tp->total_rto_recoveries++;
                tp->rto_stamp = tcp_time_stamp_ms(tp);
        }
-       icsk->icsk_retransmits++;
+       WRITE_ONCE(icsk->icsk_retransmits, icsk->icsk_retransmits + 1);
        tp->total_rto++;
 }
 

diff --git a/net/ipv6/tcp_ipv6.c b/net/ipv6/tcp_ipv6.c
index 7577e7eb2c97b821826f633a11dd5567dde7b7cb..7b177054452b983d3f49a06869950565c03c13ee 100644 (file)
--- a/net/ipv6/tcp_ipv6.c
+++ b/net/ipv6/tcp_ipv6.c
@@ -2230,7 +2230,7 @@ static void get_tcp6_sock(struct seq_file *seq, struct sock *sp, int i)
                   rx_queue,
                   timer_active,
                   jiffies_delta_to_clock_t(timer_expires - jiffies),
-                  icsk->icsk_retransmits,
+                  READ_ONCE(icsk->icsk_retransmits),
                   from_kuid_munged(seq_user_ns(seq), sk_uid(sp)),
                   icsk->icsk_probes_out,
                   sock_i_ino(sp),

diff --git a/net/mptcp/protocol.c b/net/mptcp/protocol.c
index 9a287b75c1b31bac9c35581db996e39e594872e0..f2e728239480444ffdb297efc35303848d4c4a31 100644 (file)
--- a/net/mptcp/protocol.c
+++ b/net/mptcp/protocol.c
@@ -2587,7 +2587,8 @@ static void __mptcp_retrans(struct sock *sk)
                if (mptcp_data_fin_enabled(msk)) {
                        struct inet_connection_sock *icsk = inet_csk(sk);
 
-                       icsk->icsk_retransmits++;
+                       WRITE_ONCE(icsk->icsk_retransmits,
+                                  icsk->icsk_retransmits + 1);
                        mptcp_set_datafin_timeout(sk);
                        mptcp_send_ack(msk);