mptcp: annotate data-races around subflow->fully_established

We introduce the same handling for potential data races with the
'fully_established' flag in subflow as previously done for
msk->fully_established.

Additionally, we make a crucial change: convert the subflow's
'fully_established' from 'bit_field' to 'bool' type. This is
necessary because methods for avoiding data races don't work well
with 'bit_field'. Specifically, the 'READ_ONCE' needs to know
the size of the variable being accessed, which is not supported in
'bit_field'. Also, 'test_bit' expect the address of 'bit_field'.

Closes: https://github.com/multipath-tcp/mptcp_net-next/issues/516
Signed-off-by: Gang Yan <yangang@kylinos.cn>
Reviewed-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
Signed-off-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
Link: https://patch.msgid.link/20241021-net-next-mptcp-misc-6-13-v1-2-1ef02746504a@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

diff --git a/net/mptcp/diag.c b/net/mptcp/diag.c
index 2d3efb405437d85c0bca70d7a92ca3a7363365e1..02205f7994d752cc505991efdf7aa0bbbfd830db 100644 (file)
--- a/net/mptcp/diag.c
+++ b/net/mptcp/diag.c
@@ -47,7 +47,7 @@ static int subflow_get_info(struct sock *sk, struct sk_buff *skb)
                flags |= MPTCP_SUBFLOW_FLAG_BKUP_REM;
        if (sf->request_bkup)
                flags |= MPTCP_SUBFLOW_FLAG_BKUP_LOC;
-       if (sf->fully_established)
+       if (READ_ONCE(sf->fully_established))
                flags |= MPTCP_SUBFLOW_FLAG_FULLY_ESTABLISHED;
        if (sf->conn_finished)
                flags |= MPTCP_SUBFLOW_FLAG_CONNECTED;

diff --git a/net/mptcp/options.c b/net/mptcp/options.c
index 370c3836b7712f4ca97c99d35a20e88e85a33d70..1603b3702e2207f191fdeef2b29ea2f05fd2b910 100644 (file)
--- a/net/mptcp/options.c
+++ b/net/mptcp/options.c
@@ -461,7 +461,7 @@ static bool mptcp_established_options_mp(struct sock *sk, struct sk_buff *skb,
                return false;
 
        /* MPC/MPJ needed only on 3rd ack packet, DATA_FIN and TCP shutdown take precedence */
-       if (subflow->fully_established || snd_data_fin_enable ||
+       if (READ_ONCE(subflow->fully_established) || snd_data_fin_enable ||
            subflow->snd_isn != TCP_SKB_CB(skb)->seq ||
            sk->sk_state != TCP_ESTABLISHED)
                return false;
@@ -930,7 +930,7 @@ static bool check_fully_established(struct mptcp_sock *msk, struct sock *ssk,
        /* here we can process OoO, in-window pkts, only in-sequence 4th ack
         * will make the subflow fully established
         */
-       if (likely(subflow->fully_established)) {
+       if (likely(READ_ONCE(subflow->fully_established))) {
                /* on passive sockets, check for 3rd ack retransmission
                 * note that msk is always set by subflow_syn_recv_sock()
                 * for mp_join subflows

diff --git a/net/mptcp/protocol.c b/net/mptcp/protocol.c
index 1f5c63eb21f0db92341ec941cfe2aec919cdd3de..a6c9661a4c45a00e982d0f68f21621c3cf33469b 100644 (file)
--- a/net/mptcp/protocol.c
+++ b/net/mptcp/protocol.c
@@ -3511,7 +3511,7 @@ static void schedule_3rdack_retransmission(struct sock *ssk)
        struct tcp_sock *tp = tcp_sk(ssk);
        unsigned long timeout;
 
-       if (mptcp_subflow_ctx(ssk)->fully_established)
+       if (READ_ONCE(mptcp_subflow_ctx(ssk)->fully_established))
                return;
 
        /* reschedule with a timeout above RTT, as we must look only for drop */

diff --git a/net/mptcp/protocol.h b/net/mptcp/protocol.h
index 568a72702b080d7610425ce5c3a409c7b88da13a..a93e661ef5c435155066ce9cc109092661f0711c 100644 (file)
--- a/net/mptcp/protocol.h
+++ b/net/mptcp/protocol.h
@@ -513,7 +513,6 @@ struct mptcp_subflow_context {
                request_bkup : 1,
                mp_capable : 1,     /* remote is MPTCP capable */
                mp_join : 1,        /* remote is JOINing */
-               fully_established : 1,      /* path validated */
                pm_notified : 1,    /* PM hook called for established status */
                conn_finished : 1,
                map_valid : 1,
@@ -532,10 +531,11 @@ struct mptcp_subflow_context {
                is_mptfo : 1,       /* subflow is doing TFO */
                close_event_done : 1,       /* has done the post-closed part */
                mpc_drop : 1,       /* the MPC option has been dropped in a rtx */
-               __unused : 8;
+               __unused : 9;
        bool    data_avail;
        bool    scheduled;
        bool    pm_listener;        /* a listener managed by the kernel PM? */
+       bool    fully_established;  /* path validated */
        u32     remote_nonce;
        u64     thmac;
        u32     local_nonce;
@@ -780,7 +780,7 @@ static inline bool __tcp_can_send(const struct sock *ssk)
 static inline bool __mptcp_subflow_active(struct mptcp_subflow_context *subflow)
 {
        /* can't send if JOIN hasn't completed yet (i.e. is usable for mptcp) */
-       if (subflow->request_join && !subflow->fully_established)
+       if (subflow->request_join && !READ_ONCE(subflow->fully_established))
                return false;
 
        return __tcp_can_send(mptcp_subflow_tcp_sock(subflow));

diff --git a/net/mptcp/subflow.c b/net/mptcp/subflow.c
index 6170f2fff71e4f9d64837f2ebf4d81bba224fafb..860903e0642255cf9efb39da9e24c39f6547481f 100644 (file)
--- a/net/mptcp/subflow.c
+++ b/net/mptcp/subflow.c
@@ -800,7 +800,7 @@ void __mptcp_subflow_fully_established(struct mptcp_sock *msk,
                                       const struct mptcp_options_received *mp_opt)
 {
        subflow_set_remote_key(msk, subflow, mp_opt);
-       subflow->fully_established = 1;
+       WRITE_ONCE(subflow->fully_established, true);
        WRITE_ONCE(msk->fully_established, true);
 
        if (subflow->is_mptfo)
@@ -2062,7 +2062,7 @@ static void subflow_ulp_clone(const struct request_sock *req,
        } else if (subflow_req->mp_join) {
                new_ctx->ssn_offset = subflow_req->ssn_offset;
                new_ctx->mp_join = 1;
-               new_ctx->fully_established = 1;
+               WRITE_ONCE(new_ctx->fully_established, true);
                new_ctx->remote_key_valid = 1;
                new_ctx->backup = subflow_req->backup;
                new_ctx->request_bkup = subflow_req->request_bkup;