Commit b365d955 authored by David S. Miller's avatar David S. Miller
Browse files

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: default avatarDavid S. Miller <davem@davemloft.net>
parents 42c8819b bd7c5f98

net/rds/tcp.c

+2 −1
Original line number Diff line number Diff line
@@ -127,7 +127,7 @@ void rds_tcp_restore_callbacks(struct socket *sock, 


/*

 * This is the only path that sets tc->t_sock.  Send and receive trust that

 * it is set.  The RDS_CONN_CONNECTED bit protects those paths from being

 * it is set.  The RDS_CONN_UP bit protects those paths from being

 * called while it isn't set.

 */

void rds_tcp_set_callbacks(struct socket *sock, struct rds_connection *conn)
@@ -216,6 +216,7 @@ static int rds_tcp_conn_alloc(struct rds_connection *conn, gfp_t gfp) 
	if (!tc)

		return -ENOMEM;



	mutex_init(&tc->t_conn_lock);

	tc->t_sock = NULL;

	tc->t_tinc = NULL;

	tc->t_tinc_hdr_rem = sizeof(struct rds_header);

net/rds/tcp.h

+4 −0
Original line number Diff line number Diff line
@@ -12,6 +12,10 @@ struct rds_tcp_connection { 


	struct list_head	t_tcp_node;

	struct rds_connection   *conn;

	/* t_conn_lock synchronizes the connection establishment between

	 * rds_tcp_accept_one and rds_tcp_conn_connect

	 */

	struct mutex		t_conn_lock;

	struct socket		*t_sock;

	void			*t_orig_write_space;

	void			*t_orig_data_ready;

net/rds/tcp_connect.c

+8 −0
Original line number Diff line number Diff line
@@ -78,7 +78,14 @@ int rds_tcp_conn_connect(struct rds_connection *conn) 
	struct socket *sock = NULL;

	struct sockaddr_in src, dest;

	int ret;

	struct rds_tcp_connection *tc = conn->c_transport_data;



	mutex_lock(&tc->t_conn_lock);



	if (rds_conn_up(conn)) {

		mutex_unlock(&tc->t_conn_lock);

		return 0;

	}

	ret = sock_create_kern(rds_conn_net(conn), PF_INET,

			       SOCK_STREAM, IPPROTO_TCP, &sock);

	if (ret < 0)
@@ -120,6 +127,7 @@ int rds_tcp_conn_connect(struct rds_connection *conn) 
	}



out:

	mutex_unlock(&tc->t_conn_lock);

	if (sock)

		sock_release(sock);

	return ret;

net/rds/tcp_listen.c

+36 −18
Original line number Diff line number Diff line
@@ -76,7 +76,9 @@ int rds_tcp_accept_one(struct socket *sock) 
	struct rds_connection *conn;

	int ret;

	struct inet_sock *inet;

	struct rds_tcp_connection *rs_tcp;

	struct rds_tcp_connection *rs_tcp = NULL;

	int conn_state;

	struct sock *nsk;



	ret = sock_create_kern(sock_net(sock->sk), sock->sk->sk_family,

			       sock->sk->sk_type, sock->sk->sk_protocol,
@@ -115,28 +117,44 @@ 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;

	rds_conn_transition(conn, RDS_CONN_DOWN, RDS_CONN_CONNECTING);

	mutex_lock(&rs_tcp->t_conn_lock);

	conn_state = rds_conn_state(conn);

	if (conn_state != RDS_CONN_CONNECTING && conn_state != RDS_CONN_UP)

		goto rst_nsk;

	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)) {

			goto rst_nsk;

		} 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);

	}

	rds_tcp_set_callbacks(new_sock, conn);

	rds_connect_complete(conn);

	rds_connect_complete(conn); /* marks RDS_CONN_UP */

	new_sock = NULL;

	ret = 0;

	goto out;

rst_nsk:

	/* reset the newly returned accept sock and bail */

	nsk = new_sock->sk;

	rds_tcp_stats_inc(s_tcp_listen_closed_stale);

	nsk->sk_user_data = NULL;

	nsk->sk_prot->disconnect(nsk, 0);

	tcp_done(nsk);

	new_sock = NULL;

	ret = 0;



out:

	if (rs_tcp)

		mutex_unlock(&rs_tcp->t_conn_lock);

	if (new_sock)

		sock_release(new_sock);

	return ret;

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