RDS:TCP: Synchronize rds_tcp_accept_one with rds_send_xmit when resetting t_sock

[deliverable/linux.git] / net / rds / tcp_listen.c

diff --git a/net/rds/tcp_listen.c b/net/rds/tcp_listen.c
index 0936a4a32b476fdde5c7208fc465ec3324bbcf09..0896187243d68c0ad1d3a324e7b396be367fa24e 100644 (file)
--- a/net/rds/tcp_listen.c
+++ b/net/rds/tcp_listen.c
@@ -115,24 +115,32 @@ int rds_tcp_accept_one(struct socket *sock)
         * rds_tcp_state_change() will do that cleanup
         */
        rs_tcp = (struct rds_tcp_connection *)conn->c_transport_data;
-       if (rs_tcp->t_sock &&
-           ntohl(inet->inet_saddr) < ntohl(inet->inet_daddr)) {
-               struct sock *nsk = new_sock->sk;
-
-               nsk->sk_user_data = NULL;
-               nsk->sk_prot->disconnect(nsk, 0);
-               tcp_done(nsk);
-               new_sock = NULL;
-               ret = 0;
-               goto out;
-       } else if (rs_tcp->t_sock) {
-               rds_tcp_restore_callbacks(rs_tcp->t_sock, rs_tcp);
-               conn->c_outgoing = 0;
-       }
-
        rds_conn_transition(conn, RDS_CONN_DOWN, RDS_CONN_CONNECTING);
+       if (rs_tcp->t_sock) {
+               /* Need to resolve a duelling SYN between peers.
+                * We have an outstanding SYN to this peer, which may
+                * potentially have transitioned to the RDS_CONN_UP state,
+                * so we must quiesce any send threads before resetting
+                * c_transport_data.
+                */
+               wait_event(conn->c_waitq,
+                          !test_bit(RDS_IN_XMIT, &conn->c_flags));
+               if (ntohl(inet->inet_saddr) < ntohl(inet->inet_daddr)) {
+                       struct sock *nsk = new_sock->sk;
+
+                       nsk->sk_user_data = NULL;
+                       nsk->sk_prot->disconnect(nsk, 0);
+                       tcp_done(nsk);
+                       new_sock = NULL;
+                       ret = 0;
+                       goto out;
+               } else if (rs_tcp->t_sock) {
+                       rds_tcp_restore_callbacks(rs_tcp->t_sock, rs_tcp);
+                       conn->c_outgoing = 0;
+               }
+       }
        rds_tcp_set_callbacks(new_sock, conn);
-       rds_connect_complete(conn);
+       rds_connect_complete(conn); /* marks RDS_CONN_UP */
        new_sock = NULL;
        ret = 0;