Merge branch 'rds-fixes'
Sowmini Varadhan says: ==================== RDS: TCP: sychronization during connection startup This patch series ensures that the passive (accept) side of the TCP connection used for RDS-TCP is correctly synchronized with any concurrent active (connect) attempts for a given pair of peers. Patch 1 in the series makes sure that the t_sock in struct rds_tcp_connection is only reset after any threads in rds_tcp_xmit have completed (otherwise a null-ptr deref may be encountered). Patch 2 synchronizes rds_tcp_accept_one() with the rds_tcp*connect() path. v2: review comments from Santosh Shilimkar, other spelling corrections ==================== Signed-off-by: David S. Miller <davem@davemloft.net>
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b365d955f3
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@ -127,7 +127,7 @@ void rds_tcp_restore_callbacks(struct socket *sock,
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/*
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* This is the only path that sets tc->t_sock. Send and receive trust that
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* it is set. The RDS_CONN_CONNECTED bit protects those paths from being
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* it is set. The RDS_CONN_UP bit protects those paths from being
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* called while it isn't set.
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*/
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void rds_tcp_set_callbacks(struct socket *sock, struct rds_connection *conn)
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@ -216,6 +216,7 @@ static int rds_tcp_conn_alloc(struct rds_connection *conn, gfp_t gfp)
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if (!tc)
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return -ENOMEM;
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mutex_init(&tc->t_conn_lock);
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tc->t_sock = NULL;
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tc->t_tinc = NULL;
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tc->t_tinc_hdr_rem = sizeof(struct rds_header);
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@ -12,6 +12,10 @@ struct rds_tcp_connection {
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struct list_head t_tcp_node;
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struct rds_connection *conn;
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/* t_conn_lock synchronizes the connection establishment between
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* rds_tcp_accept_one and rds_tcp_conn_connect
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*/
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struct mutex t_conn_lock;
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struct socket *t_sock;
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void *t_orig_write_space;
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void *t_orig_data_ready;
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@ -78,7 +78,14 @@ int rds_tcp_conn_connect(struct rds_connection *conn)
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struct socket *sock = NULL;
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struct sockaddr_in src, dest;
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int ret;
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struct rds_tcp_connection *tc = conn->c_transport_data;
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mutex_lock(&tc->t_conn_lock);
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if (rds_conn_up(conn)) {
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mutex_unlock(&tc->t_conn_lock);
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return 0;
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}
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ret = sock_create_kern(rds_conn_net(conn), PF_INET,
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SOCK_STREAM, IPPROTO_TCP, &sock);
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if (ret < 0)
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@ -120,6 +127,7 @@ int rds_tcp_conn_connect(struct rds_connection *conn)
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}
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out:
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mutex_unlock(&tc->t_conn_lock);
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if (sock)
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sock_release(sock);
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return ret;
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@ -76,7 +76,9 @@ int rds_tcp_accept_one(struct socket *sock)
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struct rds_connection *conn;
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int ret;
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struct inet_sock *inet;
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struct rds_tcp_connection *rs_tcp;
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struct rds_tcp_connection *rs_tcp = NULL;
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int conn_state;
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struct sock *nsk;
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ret = sock_create_kern(sock_net(sock->sk), sock->sk->sk_family,
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sock->sk->sk_type, sock->sk->sk_protocol,
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@ -115,28 +117,44 @@ int rds_tcp_accept_one(struct socket *sock)
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* rds_tcp_state_change() will do that cleanup
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*/
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rs_tcp = (struct rds_tcp_connection *)conn->c_transport_data;
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if (rs_tcp->t_sock &&
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ntohl(inet->inet_saddr) < ntohl(inet->inet_daddr)) {
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struct sock *nsk = new_sock->sk;
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nsk->sk_user_data = NULL;
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nsk->sk_prot->disconnect(nsk, 0);
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tcp_done(nsk);
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new_sock = NULL;
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ret = 0;
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goto out;
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} else if (rs_tcp->t_sock) {
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rds_tcp_restore_callbacks(rs_tcp->t_sock, rs_tcp);
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conn->c_outgoing = 0;
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}
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rds_conn_transition(conn, RDS_CONN_DOWN, RDS_CONN_CONNECTING);
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mutex_lock(&rs_tcp->t_conn_lock);
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conn_state = rds_conn_state(conn);
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if (conn_state != RDS_CONN_CONNECTING && conn_state != RDS_CONN_UP)
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goto rst_nsk;
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if (rs_tcp->t_sock) {
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/* Need to resolve a duelling SYN between peers.
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* We have an outstanding SYN to this peer, which may
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* potentially have transitioned to the RDS_CONN_UP state,
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* so we must quiesce any send threads before resetting
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* c_transport_data.
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*/
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wait_event(conn->c_waitq,
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!test_bit(RDS_IN_XMIT, &conn->c_flags));
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if (ntohl(inet->inet_saddr) < ntohl(inet->inet_daddr)) {
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goto rst_nsk;
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} else if (rs_tcp->t_sock) {
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rds_tcp_restore_callbacks(rs_tcp->t_sock, rs_tcp);
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conn->c_outgoing = 0;
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}
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}
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rds_tcp_set_callbacks(new_sock, conn);
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rds_connect_complete(conn);
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rds_connect_complete(conn); /* marks RDS_CONN_UP */
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new_sock = NULL;
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ret = 0;
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goto out;
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rst_nsk:
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/* reset the newly returned accept sock and bail */
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nsk = new_sock->sk;
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rds_tcp_stats_inc(s_tcp_listen_closed_stale);
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nsk->sk_user_data = NULL;
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nsk->sk_prot->disconnect(nsk, 0);
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tcp_done(nsk);
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new_sock = NULL;
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ret = 0;
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out:
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if (rs_tcp)
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mutex_unlock(&rs_tcp->t_conn_lock);
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if (new_sock)
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sock_release(new_sock);
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return ret;
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