Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next

Pull networking updates from David Miller:

 1) Unified UDP encapsulation offload methods for drivers, from
    Alexander Duyck.

 2) Make DSA binding more sane, from Andrew Lunn.

 3) Support QCA9888 chips in ath10k, from Anilkumar Kolli.

 4) Several workqueue usage cleanups, from Bhaktipriya Shridhar.

 5) Add XDP (eXpress Data Path), essentially running BPF programs on RX
    packets as soon as the device sees them, with the option to mirror
    the packet on TX via the same interface.  From Brenden Blanco and
    others.

 6) Allow qdisc/class stats dumps to run lockless, from Eric Dumazet.

 7) Add VLAN support to b53 and bcm_sf2, from Florian Fainelli.

 8) Simplify netlink conntrack entry layout, from Florian Westphal.

 9) Add ipv4 forwarding support to mlxsw spectrum driver, from Ido
    Schimmel, Yotam Gigi, and Jiri Pirko.

10) Add SKB array infrastructure and convert tun and macvtap over to it.
    From Michael S Tsirkin and Jason Wang.

11) Support qdisc packet injection in pktgen, from John Fastabend.

12) Add neighbour monitoring framework to TIPC, from Jon Paul Maloy.

13) Add NV congestion control support to TCP, from Lawrence Brakmo.

14) Add GSO support to SCTP, from Marcelo Ricardo Leitner.

15) Allow GRO and RPS to function on macsec devices, from Paolo Abeni.

16) Support MPLS over IPV4, from Simon Horman.

* git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next: (1622 commits)
  xgene: Fix build warning with ACPI disabled.
  be2net: perform temperature query in adapter regardless of its interface state
  l2tp: Correctly return -EBADF from pppol2tp_getname.
  net/mlx5_core/health: Remove deprecated create_singlethread_workqueue
  net: ipmr/ip6mr: update lastuse on entry change
  macsec: ensure rx_sa is set when validation is disabled
  tipc: dump monitor attributes
  tipc: add a function to get the bearer name
  tipc: get monitor threshold for the cluster
  tipc: make cluster size threshold for monitoring configurable
  tipc: introduce constants for tipc address validation
  net: neigh: disallow transition to NUD_STALE if lladdr is unchanged in neigh_update()
  MAINTAINERS: xgene: Add driver and documentation path
  Documentation: dtb: xgene: Add MDIO node
  dtb: xgene: Add MDIO node
  drivers: net: xgene: ethtool: Use phy_ethtool_gset and sset
  drivers: net: xgene: Use exported functions
  drivers: net: xgene: Enable MDIO driver
  drivers: net: xgene: Add backward compatibility
  drivers: net: phy: xgene: Add MDIO driver
  ...

23 files changed, 1035 insertions, 511 deletions

diff --git a/net/rds/bind.c b/net/rds/bind.c
index b22ea956522b..095f6ce583fe 100644
--- a/net/rds/bind.c
+++ b/net/rds/bind.c
@@ -81,6 +81,8 @@ static int rds_add_bound(struct rds_sock *rs, __be32 addr, __be16 *port)
 
 	if (*port != 0) {
 		rover = be16_to_cpu(*port);
+		if (rover == RDS_FLAG_PROBE_PORT)
+			return -EINVAL;
 		last = rover;
 	} else {
 		rover = max_t(u16, prandom_u32(), 2);
@@ -91,12 +93,16 @@ static int rds_add_bound(struct rds_sock *rs, __be32 addr, __be16 *port)
 		if (rover == 0)
 			rover++;
 
+		if (rover == RDS_FLAG_PROBE_PORT)
+			continue;
 		key = ((u64)addr << 32) | cpu_to_be16(rover);
 		if (rhashtable_lookup_fast(&bind_hash_table, &key, ht_parms))
 			continue;
 
 		rs->rs_bound_key = key;
 		rs->rs_bound_addr = addr;
+		net_get_random_once(&rs->rs_hash_initval,
+				    sizeof(rs->rs_hash_initval));
 		rs->rs_bound_port = cpu_to_be16(rover);
 		rs->rs_bound_node.next = NULL;
 		rds_sock_addref(rs);
diff --git a/net/rds/cong.c b/net/rds/cong.c
index 6641bcf7c185..8398fee7c866 100644
--- a/net/rds/cong.c
+++ b/net/rds/cong.c
@@ -235,7 +235,8 @@ void rds_cong_queue_updates(struct rds_cong_map *map)
 			 *    therefore trigger warnings.
 			 * Defer the xmit to rds_send_worker() instead.
 			 */
-			queue_delayed_work(rds_wq, &conn->c_send_w, 0);
+			queue_delayed_work(rds_wq,
+					   &conn->c_path[0].cp_send_w, 0);
 		}
 	}
 
diff --git a/net/rds/connection.c b/net/rds/connection.c
index e3b118cae81d..f5058559bb08 100644
--- a/net/rds/connection.c
+++ b/net/rds/connection.c
@@ -95,14 +95,16 @@ static struct rds_connection *rds_conn_lookup(struct net *net,
  * and receiving over this connection again in the future.  It is up to
  * the transport to have serialized this call with its send and recv.
  */
-static void rds_conn_reset(struct rds_connection *conn)
+static void rds_conn_path_reset(struct rds_conn_path *cp)
 {
+	struct rds_connection *conn = cp->cp_conn;
+
 	rdsdebug("connection %pI4 to %pI4 reset\n",
 	  &conn->c_laddr, &conn->c_faddr);
 
 	rds_stats_inc(s_conn_reset);
-	rds_send_reset(conn);
-	conn->c_flags = 0;
+	rds_send_path_reset(cp);
+	cp->cp_flags = 0;
 
 	/* Do not clear next_rx_seq here, else we cannot distinguish
 	 * retransmitted packets from new packets, and will hand all
@@ -110,6 +112,32 @@ static void rds_conn_reset(struct rds_connection *conn)
 	 * reliability guarantees of RDS. */
 }
 
+static void __rds_conn_path_init(struct rds_connection *conn,
+				 struct rds_conn_path *cp, bool is_outgoing)
+{
+	spin_lock_init(&cp->cp_lock);
+	cp->cp_next_tx_seq = 1;
+	init_waitqueue_head(&cp->cp_waitq);
+	INIT_LIST_HEAD(&cp->cp_send_queue);
+	INIT_LIST_HEAD(&cp->cp_retrans);
+
+	cp->cp_conn = conn;
+	atomic_set(&cp->cp_state, RDS_CONN_DOWN);
+	cp->cp_send_gen = 0;
+	/* cp_outgoing is per-path. So we can only set it here
+	 * for the single-path transports.
+	 */
+	if (!conn->c_trans->t_mp_capable)
+		cp->cp_outgoing = (is_outgoing ? 1 : 0);
+	cp->cp_reconnect_jiffies = 0;
+	INIT_DELAYED_WORK(&cp->cp_send_w, rds_send_worker);
+	INIT_DELAYED_WORK(&cp->cp_recv_w, rds_recv_worker);
+	INIT_DELAYED_WORK(&cp->cp_conn_w, rds_connect_worker);
+	INIT_WORK(&cp->cp_down_w, rds_shutdown_worker);
+	mutex_init(&cp->cp_cm_lock);
+	cp->cp_flags = 0;
+}
+
 /*
  * There is only every one 'conn' for a given pair of addresses in the
  * system at a time.  They contain messages to be retransmitted and so
@@ -127,7 +155,7 @@ static struct rds_connection *__rds_conn_create(struct net *net,
 	struct hlist_head *head = rds_conn_bucket(laddr, faddr);
 	struct rds_transport *loop_trans;
 	unsigned long flags;
-	int ret;
+	int ret, i;
 
 	rcu_read_lock();
 	conn = rds_conn_lookup(net, head, laddr, faddr, trans);
@@ -153,13 +181,8 @@ static struct rds_connection *__rds_conn_create(struct net *net,
 	INIT_HLIST_NODE(&conn->c_hash_node);
 	conn->c_laddr = laddr;
 	conn->c_faddr = faddr;
-	spin_lock_init(&conn->c_lock);
-	conn->c_next_tx_seq = 1;
-	rds_conn_net_set(conn, net);
 
-	init_waitqueue_head(&conn->c_waitq);
-	INIT_LIST_HEAD(&conn->c_send_queue);
-	INIT_LIST_HEAD(&conn->c_retrans);
+	rds_conn_net_set(conn, net);
 
 	ret = rds_cong_get_maps(conn);
 	if (ret) {
@@ -188,6 +211,12 @@ static struct rds_connection *__rds_conn_create(struct net *net,
 
 	conn->c_trans = trans;
 
+	init_waitqueue_head(&conn->c_hs_waitq);
+	for (i = 0; i < RDS_MPATH_WORKERS; i++) {
+		__rds_conn_path_init(conn, &conn->c_path[i],
+				     is_outgoing);
+		conn->c_path[i].cp_index = i;
+	}
 	ret = trans->conn_alloc(conn, gfp);
 	if (ret) {
 		kmem_cache_free(rds_conn_slab, conn);
@@ -195,17 +224,6 @@ static struct rds_connection *__rds_conn_create(struct net *net,
 		goto out;
 	}
 
-	atomic_set(&conn->c_state, RDS_CONN_DOWN);
-	conn->c_send_gen = 0;
-	conn->c_outgoing = (is_outgoing ? 1 : 0);
-	conn->c_reconnect_jiffies = 0;
-	INIT_DELAYED_WORK(&conn->c_send_w, rds_send_worker);
-	INIT_DELAYED_WORK(&conn->c_recv_w, rds_recv_worker);
-	INIT_DELAYED_WORK(&conn->c_conn_w, rds_connect_worker);
-	INIT_WORK(&conn->c_down_w, rds_shutdown_worker);
-	mutex_init(&conn->c_cm_lock);
-	conn->c_flags = 0;
-
 	rdsdebug("allocated conn %p for %pI4 -> %pI4 over %s %s\n",
 	  conn, &laddr, &faddr,
 	  trans->t_name ? trans->t_name : "[unknown]",
@@ -222,7 +240,7 @@ static struct rds_connection *__rds_conn_create(struct net *net,
 	if (parent) {
 		/* Creating passive conn */
 		if (parent->c_passive) {
-			trans->conn_free(conn->c_transport_data);
+			trans->conn_free(conn->c_path[0].cp_transport_data);
 			kmem_cache_free(rds_conn_slab, conn);
 			conn = parent->c_passive;
 		} else {
@@ -236,7 +254,18 @@ static struct rds_connection *__rds_conn_create(struct net *net,
 
 		found = rds_conn_lookup(net, head, laddr, faddr, trans);
 		if (found) {
-			trans->conn_free(conn->c_transport_data);
+			struct rds_conn_path *cp;
+			int i;
+
+			for (i = 0; i < RDS_MPATH_WORKERS; i++) {
+				cp = &conn->c_path[i];
+				/* The ->conn_alloc invocation may have
+				 * allocated resource for all paths, so all
+				 * of them may have to be freed here.
+				 */
+				if (cp->cp_transport_data)
+					trans->conn_free(cp->cp_transport_data);
+			}
 			kmem_cache_free(rds_conn_slab, conn);
 			conn = found;
 		} else {
@@ -267,10 +296,12 @@ struct rds_connection *rds_conn_create_outgoing(struct net *net,
 }
 EXPORT_SYMBOL_GPL(rds_conn_create_outgoing);
 
-void rds_conn_shutdown(struct rds_connection *conn)
+void rds_conn_shutdown(struct rds_conn_path *cp)
 {
+	struct rds_connection *conn = cp->cp_conn;
+
 	/* shut it down unless it's down already */
-	if (!rds_conn_transition(conn, RDS_CONN_DOWN, RDS_CONN_DOWN)) {
+	if (!rds_conn_path_transition(cp, RDS_CONN_DOWN, RDS_CONN_DOWN)) {
 		/*
 		 * Quiesce the connection mgmt handlers before we start tearing
 		 * things down. We don't hold the mutex for the entire
@@ -278,35 +309,38 @@ void rds_conn_shutdown(struct rds_connection *conn)
 		 * deadlocking with the CM handler. Instead, the CM event
 		 * handler is supposed to check for state DISCONNECTING
 		 */
-		mutex_lock(&conn->c_cm_lock);
-		if (!rds_conn_transition(conn, RDS_CONN_UP, RDS_CONN_DISCONNECTING)
-		 && !rds_conn_transition(conn, RDS_CONN_ERROR, RDS_CONN_DISCONNECTING)) {
-			rds_conn_error(conn, "shutdown called in state %d\n",
-					atomic_read(&conn->c_state));
-			mutex_unlock(&conn->c_cm_lock);
+		mutex_lock(&cp->cp_cm_lock);
+		if (!rds_conn_path_transition(cp, RDS_CONN_UP,
+					      RDS_CONN_DISCONNECTING) &&
+		    !rds_conn_path_transition(cp, RDS_CONN_ERROR,
+					      RDS_CONN_DISCONNECTING)) {
+			rds_conn_path_error(cp,
+					    "shutdown called in state %d\n",
+					    atomic_read(&cp->cp_state));
+			mutex_unlock(&cp->cp_cm_lock);
 			return;
 		}
-		mutex_unlock(&conn->c_cm_lock);
+		mutex_unlock(&cp->cp_cm_lock);
 
-		wait_event(conn->c_waitq,
-			   !test_bit(RDS_IN_XMIT, &conn->c_flags));
-		wait_event(conn->c_waitq,
-			   !test_bit(RDS_RECV_REFILL, &conn->c_flags));
+		wait_event(cp->cp_waitq,
+			   !test_bit(RDS_IN_XMIT, &cp->cp_flags));
+		wait_event(cp->cp_waitq,
+			   !test_bit(RDS_RECV_REFILL, &cp->cp_flags));
 
-		conn->c_trans->conn_shutdown(conn);
-		rds_conn_reset(conn);
+		conn->c_trans->conn_path_shutdown(cp);
+		rds_conn_path_reset(cp);
 
-		if (!rds_conn_transition(conn, RDS_CONN_DISCONNECTING, RDS_CONN_DOWN)) {
+		if (!rds_conn_path_transition(cp, RDS_CONN_DISCONNECTING,
+					      RDS_CONN_DOWN)) {
 			/* This can happen - eg when we're in the middle of tearing
 			 * down the connection, and someone unloads the rds module.
 			 * Quite reproduceable with loopback connections.
 			 * Mostly harmless.
 			 */
-			rds_conn_error(conn,
-				"%s: failed to transition to state DOWN, "
-				"current state is %d\n",
-				__func__,
-				atomic_read(&conn->c_state));
+			rds_conn_path_error(cp, "%s: failed to transition "
+					    "to state DOWN, current state "
+					    "is %d\n", __func__,
+					    atomic_read(&cp->cp_state));
 			return;
 		}
 	}
@@ -315,18 +349,47 @@ void rds_conn_shutdown(struct rds_connection *conn)
 	 * The passive side of an IB loopback connection is never added
 	 * to the conn hash, so we never trigger a reconnect on this
 	 * conn - the reconnect is always triggered by the active peer. */
-	cancel_delayed_work_sync(&conn->c_conn_w);
+	cancel_delayed_work_sync(&cp->cp_conn_w);
 	rcu_read_lock();
 	if (!hlist_unhashed(&conn->c_hash_node)) {
 		rcu_read_unlock();
-		if (conn->c_trans->t_type != RDS_TRANS_TCP ||
-		    conn->c_outgoing == 1)
-			rds_queue_reconnect(conn);
+		rds_queue_reconnect(cp);
 	} else {
 		rcu_read_unlock();
 	}
 }
 
+/* destroy a single rds_conn_path. rds_conn_destroy() iterates over
+ * all paths using rds_conn_path_destroy()
+ */
+static void rds_conn_path_destroy(struct rds_conn_path *cp)
+{
+	struct rds_message *rm, *rtmp;
+
+	if (!cp->cp_transport_data)
+		return;
+
+	rds_conn_path_drop(cp);
+	flush_work(&cp->cp_down_w);
+
+	/* make sure lingering queued work won't try to ref the conn */
+	cancel_delayed_work_sync(&cp->cp_send_w);
+	cancel_delayed_work_sync(&cp->cp_recv_w);
+
+	/* tear down queued messages */
+	list_for_each_entry_safe(rm, rtmp,
+				 &cp->cp_send_queue,
+				 m_conn_item) {
+		list_del_init(&rm->m_conn_item);
+		BUG_ON(!list_empty(&rm->m_sock_item));
+		rds_message_put(rm);
+	}
+	if (cp->cp_xmit_rm)
+		rds_message_put(cp->cp_xmit_rm);
+
+	cp->cp_conn->c_trans->conn_free(cp->cp_transport_data);
+}
+
 /*
  * Stop and free a connection.
  *
@@ -336,8 +399,9 @@ void rds_conn_shutdown(struct rds_connection *conn)
  */
 void rds_conn_destroy(struct rds_connection *conn)
 {
-	struct rds_message *rm, *rtmp;
 	unsigned long flags;
+	int i;
+	struct rds_conn_path *cp;
 
 	rdsdebug("freeing conn %p for %pI4 -> "
 		 "%pI4\n", conn, &conn->c_laddr,
@@ -350,25 +414,11 @@ void rds_conn_destroy(struct rds_connection *conn)
 	synchronize_rcu();
 
 	/* shut the connection down */
-	rds_conn_drop(conn);
-	flush_work(&conn->c_down_w);
-
-	/* make sure lingering queued work won't try to ref the conn */
-	cancel_delayed_work_sync(&conn->c_send_w);
-	cancel_delayed_work_sync(&conn->c_recv_w);
-
-	/* tear down queued messages */
-	list_for_each_entry_safe(rm, rtmp,
-				 &conn->c_send_queue,
-				 m_conn_item) {
-		list_del_init(&rm->m_conn_item);
-		BUG_ON(!list_empty(&rm->m_sock_item));
-		rds_message_put(rm);
+	for (i = 0; i < RDS_MPATH_WORKERS; i++) {
+		cp = &conn->c_path[i];
+		rds_conn_path_destroy(cp);
+		BUG_ON(!list_empty(&cp->cp_retrans));
 	}
-	if (conn->c_xmit_rm)
-		rds_message_put(conn->c_xmit_rm);
-
-	conn->c_trans->conn_free(conn->c_transport_data);
 
 	/*
 	 * The congestion maps aren't freed up here.  They're
@@ -377,7 +427,6 @@ void rds_conn_destroy(struct rds_connection *conn)
 	 */
 	rds_cong_remove_conn(conn);
 
-	BUG_ON(!list_empty(&conn->c_retrans));
 	kmem_cache_free(rds_conn_slab, conn);
 
 	spin_lock_irqsave(&rds_conn_lock, flags);
@@ -398,6 +447,7 @@ static void rds_conn_message_info(struct socket *sock, unsigned int len,
 	unsigned int total = 0;
 	unsigned long flags;
 	size_t i;
+	int j;
 
 	len /= sizeof(struct rds_info_message);
 
@@ -406,23 +456,32 @@ static void rds_conn_message_info(struct socket *sock, unsigned int len,
 	for (i = 0, head = rds_conn_hash; i < ARRAY_SIZE(rds_conn_hash);
 	     i++, head++) {
 		hlist_for_each_entry_rcu(conn, head, c_hash_node) {
-			if (want_send)
-				list = &conn->c_send_queue;
-			else
-				list = &conn->c_retrans;
-
-			spin_lock_irqsave(&conn->c_lock, flags);
-
-			/* XXX too lazy to maintain counts.. */
-			list_for_each_entry(rm, list, m_conn_item) {
-				total++;
-				if (total <= len)
-					rds_inc_info_copy(&rm->m_inc, iter,
-							  conn->c_laddr,
-							  conn->c_faddr, 0);
+			struct rds_conn_path *cp;
+
+			for (j = 0; j < RDS_MPATH_WORKERS; j++) {
+				cp = &conn->c_path[j];
+				if (want_send)
+					list = &cp->cp_send_queue;
+				else
+					list = &cp->cp_retrans;
+
+				spin_lock_irqsave(&cp->cp_lock, flags);
+
+				/* XXX too lazy to maintain counts.. */
+				list_for_each_entry(rm, list, m_conn_item) {
+					total++;
+					if (total <= len)
+						rds_inc_info_copy(&rm->m_inc,
+								  iter,
+								  conn->c_laddr,
+								  conn->c_faddr,
+								  0);
+				}
+
+				spin_unlock_irqrestore(&cp->cp_lock, flags);
+				if (!conn->c_trans->t_mp_capable)
+					break;
 			}
-
-			spin_unlock_irqrestore(&conn->c_lock, flags);
 		}
 	}
 	rcu_read_unlock();
@@ -484,27 +543,72 @@ void rds_for_each_conn_info(struct socket *sock, unsigned int len,
 }
 EXPORT_SYMBOL_GPL(rds_for_each_conn_info);
 
-static int rds_conn_info_visitor(struct rds_connection *conn,
-				  void *buffer)
+void rds_walk_conn_path_info(struct socket *sock, unsigned int len,
+			     struct rds_info_iterator *iter,
+			     struct rds_info_lengths *lens,
+			     int (*visitor)(struct rds_conn_path *, void *),
+			     size_t item_len)
+{
+	u64  buffer[(item_len + 7) / 8];
+	struct hlist_head *head;
+	struct rds_connection *conn;
+	size_t i;
+	int j;
+
+	rcu_read_lock();
+
+	lens->nr = 0;
+	lens->each = item_len;
+
+	for (i = 0, head = rds_conn_hash; i < ARRAY_SIZE(rds_conn_hash);
+	     i++, head++) {
+		hlist_for_each_entry_rcu(conn, head, c_hash_node) {
+			struct rds_conn_path *cp;
+
+			for (j = 0; j < RDS_MPATH_WORKERS; j++) {
+				cp = &conn->c_path[j];
+
+				/* XXX no cp_lock usage.. */
+				if (!visitor(cp, buffer))
+					continue;
+				if (!conn->c_trans->t_mp_capable)
+					break;
+			}
+
+			/* We copy as much as we can fit in the buffer,
+			 * but we count all items so that the caller
+			 * can resize the buffer.
+			 */
+			if (len >= item_len) {
+				rds_info_copy(iter, buffer, item_len);
+				len -= item_len;
+			}
+			lens->nr++;
+		}
+	}
+	rcu_read_unlock();
+}
+
+static int rds_conn_info_visitor(struct rds_conn_path *cp, void *buffer)
 {
 	struct rds_info_connection *cinfo = buffer;
 
-	cinfo->next_tx_seq = conn->c_next_tx_seq;
-	cinfo->next_rx_seq = conn->c_next_rx_seq;
-	cinfo->laddr = conn->c_laddr;
-	cinfo->faddr = conn->c_faddr;
-	strncpy(cinfo->transport, conn->c_trans->t_name,
+	cinfo->next_tx_seq = cp->cp_next_tx_seq;
+	cinfo->next_rx_seq = cp->cp_next_rx_seq;
+	cinfo->laddr = cp->cp_conn->c_laddr;
+	cinfo->faddr = cp->cp_conn->c_faddr;
+	strncpy(cinfo->transport, cp->cp_conn->c_trans->t_name,
 		sizeof(cinfo->transport));
 	cinfo->flags = 0;
 
-	rds_conn_info_set(cinfo->flags, test_bit(RDS_IN_XMIT, &conn->c_flags),
+	rds_conn_info_set(cinfo->flags, test_bit(RDS_IN_XMIT, &cp->cp_flags),
 			  SENDING);
 	/* XXX Future: return the state rather than these funky bits */
 	rds_conn_info_set(cinfo->flags,
-			  atomic_read(&conn->c_state) == RDS_CONN_CONNECTING,
+			  atomic_read(&cp->cp_state) == RDS_CONN_CONNECTING,
 			  CONNECTING);
 	rds_conn_info_set(cinfo->flags,
-			  atomic_read(&conn->c_state) == RDS_CONN_UP,
+			  atomic_read(&cp->cp_state) == RDS_CONN_UP,
 			  CONNECTED);
 	return 1;
 }
@@ -513,7 +617,7 @@ static void rds_conn_info(struct socket *sock, unsigned int len,
 			  struct rds_info_iterator *iter,
 			  struct rds_info_lengths *lens)
 {
-	rds_for_each_conn_info(sock, len, iter, lens,
+	rds_walk_conn_path_info(sock, len, iter, lens,
 				rds_conn_info_visitor,
 				sizeof(struct rds_info_connection));
 }
@@ -553,10 +657,17 @@ void rds_conn_exit(void)
 /*
  * Force a disconnect
  */
+void rds_conn_path_drop(struct rds_conn_path *cp)
+{
+	atomic_set(&cp->cp_state, RDS_CONN_ERROR);
+	queue_work(rds_wq, &cp->cp_down_w);
+}
+EXPORT_SYMBOL_GPL(rds_conn_path_drop);
+
 void rds_conn_drop(struct rds_connection *conn)
 {
-	atomic_set(&conn->c_state, RDS_CONN_ERROR);
-	queue_work(rds_wq, &conn->c_down_w);
+	WARN_ON(conn->c_trans->t_mp_capable);
+	rds_conn_path_drop(&conn->c_path[0]);
 }
 EXPORT_SYMBOL_GPL(rds_conn_drop);
 
@@ -564,11 +675,17 @@ EXPORT_SYMBOL_GPL(rds_conn_drop);
  * If the connection is down, trigger a connect. We may have scheduled a
  * delayed reconnect however - in this case we should not interfere.
  */
+void rds_conn_path_connect_if_down(struct rds_conn_path *cp)
+{
+	if (rds_conn_path_state(cp) == RDS_CONN_DOWN &&
+	    !test_and_set_bit(RDS_RECONNECT_PENDING, &cp->cp_flags))
+		queue_delayed_work(rds_wq, &cp->cp_conn_w, 0);
+}
+
 void rds_conn_connect_if_down(struct rds_connection *conn)
 {
-	if (rds_conn_state(conn) == RDS_CONN_DOWN &&
-	    !test_and_set_bit(RDS_RECONNECT_PENDING, &conn->c_flags))
-		queue_delayed_work(rds_wq, &conn->c_conn_w, 0);
+	WARN_ON(conn->c_trans->t_mp_capable);
+	rds_conn_path_connect_if_down(&conn->c_path[0]);
 }
 EXPORT_SYMBOL_GPL(rds_conn_connect_if_down);
 
@@ -586,3 +703,15 @@ __rds_conn_error(struct rds_connection *conn, const char *fmt, ...)
 
 	rds_conn_drop(conn);
 }
+
+void
+__rds_conn_path_error(struct rds_conn_path *cp, const char *fmt, ...)
+{
+	va_list ap;
+
+	va_start(ap, fmt);
+	vprintk(fmt, ap);
+	va_end(ap);
+
+	rds_conn_path_drop(cp);
+}
diff --git a/net/rds/ib.c b/net/rds/ib.c
index b5342fddaf98..7eaf887e46f8 100644
--- a/net/rds/ib.c
+++ b/net/rds/ib.c
@@ -40,6 +40,7 @@
 #include <linux/slab.h>
 #include <linux/module.h>
 
+#include "rds_single_path.h"
 #include "rds.h"
 #include "ib.h"
 #include "ib_mr.h"
@@ -380,15 +381,15 @@ void rds_ib_exit(void)
 
 struct rds_transport rds_ib_transport = {
 	.laddr_check		= rds_ib_laddr_check,
-	.xmit_complete		= rds_ib_xmit_complete,
+	.xmit_path_complete	= rds_ib_xmit_path_complete,
 	.xmit			= rds_ib_xmit,
 	.xmit_rdma		= rds_ib_xmit_rdma,
 	.xmit_atomic		= rds_ib_xmit_atomic,
-	.recv			= rds_ib_recv,
+	.recv_path		= rds_ib_recv_path,
 	.conn_alloc		= rds_ib_conn_alloc,
 	.conn_free		= rds_ib_conn_free,
-	.conn_connect		= rds_ib_conn_connect,
-	.conn_shutdown		= rds_ib_conn_shutdown,
+	.conn_path_connect	= rds_ib_conn_path_connect,
+	.conn_path_shutdown	= rds_ib_conn_path_shutdown,
 	.inc_copy_to_user	= rds_ib_inc_copy_to_user,
 	.inc_free		= rds_ib_inc_free,
 	.cm_initiate_connect	= rds_ib_cm_initiate_connect,
diff --git a/net/rds/ib.h b/net/rds/ib.h
index 627fb79aee65..046f7508c06b 100644
--- a/net/rds/ib.h
+++ b/net/rds/ib.h
@@ -328,8 +328,8 @@ extern struct list_head ib_nodev_conns;
 /* ib_cm.c */
 int rds_ib_conn_alloc(struct rds_connection *conn, gfp_t gfp);
 void rds_ib_conn_free(void *arg);
-int rds_ib_conn_connect(struct rds_connection *conn);
-void rds_ib_conn_shutdown(struct rds_connection *conn);
+int rds_ib_conn_path_connect(struct rds_conn_path *cp);
+void rds_ib_conn_path_shutdown(struct rds_conn_path *cp);
 void rds_ib_state_change(struct sock *sk);
 int rds_ib_listen_init(void);
 void rds_ib_listen_stop(void);
@@ -354,7 +354,7 @@ void rds_ib_mr_cqe_handler(struct rds_ib_connection *ic, struct ib_wc *wc);
 /* ib_recv.c */
 int rds_ib_recv_init(void);
 void rds_ib_recv_exit(void);
-int rds_ib_recv(struct rds_connection *conn);
+int rds_ib_recv_path(struct rds_conn_path *conn);
 int rds_ib_recv_alloc_caches(struct rds_ib_connection *ic);
 void rds_ib_recv_free_caches(struct rds_ib_connection *ic);
 void rds_ib_recv_refill(struct rds_connection *conn, int prefill, gfp_t gfp);
@@ -384,7 +384,7 @@ u32 rds_ib_ring_completed(struct rds_ib_work_ring *ring, u32 wr_id, u32 oldest);
 extern wait_queue_head_t rds_ib_ring_empty_wait;
 
 /* ib_send.c */
-void rds_ib_xmit_complete(struct rds_connection *conn);
+void rds_ib_xmit_path_complete(struct rds_conn_path *cp);
 int rds_ib_xmit(struct rds_connection *conn, struct rds_message *rm,
 		unsigned int hdr_off, unsigned int sg, unsigned int off);
 void rds_ib_send_cqe_handler(struct rds_ib_connection *ic, struct ib_wc *wc);
diff --git a/net/rds/ib_cm.c b/net/rds/ib_cm.c
index 7c2a65a6af5c..5b2ab95afa07 100644
--- a/net/rds/ib_cm.c
+++ b/net/rds/ib_cm.c
@@ -36,6 +36,7 @@
 #include <linux/vmalloc.h>
 #include <linux/ratelimit.h>
 
+#include "rds_single_path.h"
 #include "rds.h"
 #include "ib.h"
 
@@ -273,7 +274,7 @@ static void rds_ib_tasklet_fn_send(unsigned long data)
 	if (rds_conn_up(conn) &&
 	    (!test_bit(RDS_LL_SEND_FULL, &conn->c_flags) ||
 	    test_bit(0, &conn->c_map_queued)))
-		rds_send_xmit(ic->conn);
+		rds_send_xmit(&ic->conn->c_path[0]);
 }
 
 static void poll_rcq(struct rds_ib_connection *ic, struct ib_cq *cq,
@@ -684,8 +685,9 @@ out:
 	return ret;
 }
 
-int rds_ib_conn_connect(struct rds_connection *conn)
+int rds_ib_conn_path_connect(struct rds_conn_path *cp)
 {
+	struct rds_connection *conn = cp->cp_conn;
 	struct rds_ib_connection *ic = conn->c_transport_data;
 	struct sockaddr_in src, dest;
 	int ret;
@@ -730,8 +732,9 @@ out:
  * so that it can be called at any point during startup.  In fact it
  * can be called multiple times for a given connection.
  */
-void rds_ib_conn_shutdown(struct rds_connection *conn)
+void rds_ib_conn_path_shutdown(struct rds_conn_path *cp)
 {
+	struct rds_connection *conn = cp->cp_conn;
 	struct rds_ib_connection *ic = conn->c_transport_data;
 	int err = 0;
 
diff --git a/net/rds/ib_rdma.c b/net/rds/ib_rdma.c
index f7164ac1ffc1..977f69886c00 100644
--- a/net/rds/ib_rdma.c
+++ b/net/rds/ib_rdma.c
@@ -35,6 +35,7 @@
 #include <linux/rculist.h>
 #include <linux/llist.h>
 
+#include "rds_single_path.h"
 #include "ib_mr.h"
 
 struct workqueue_struct *rds_ib_mr_wq;
@@ -618,7 +619,7 @@ struct rds_ib_mr_pool *rds_ib_create_mr_pool(struct rds_ib_device *rds_ibdev,
 
 int rds_ib_mr_init(void)
 {
-	rds_ib_mr_wq = create_workqueue("rds_mr_flushd");
+	rds_ib_mr_wq = alloc_workqueue("rds_mr_flushd", WQ_MEM_RECLAIM, 0);
 	if (!rds_ib_mr_wq)
 		return -ENOMEM;
 	return 0;
diff --git a/net/rds/ib_recv.c b/net/rds/ib_recv.c
index abc8cc805e8d..606a11f681d2 100644
--- a/net/rds/ib_recv.c
+++ b/net/rds/ib_recv.c
@@ -36,6 +36,7 @@
 #include <linux/dma-mapping.h>
 #include <rdma/rdma_cm.h>
 
+#include "rds_single_path.h"
 #include "rds.h"
 #include "ib.h"
 
@@ -1008,8 +1009,9 @@ void rds_ib_recv_cqe_handler(struct rds_ib_connection *ic,
 		rds_ib_recv_refill(conn, 0, GFP_NOWAIT);
 }
 
-int rds_ib_recv(struct rds_connection *conn)
+int rds_ib_recv_path(struct rds_conn_path *cp)
 {
+	struct rds_connection *conn = cp->cp_conn;
 	struct rds_ib_connection *ic = conn->c_transport_data;
 	int ret = 0;
 
diff --git a/net/rds/ib_send.c b/net/rds/ib_send.c
index f27d2c82b036..84d90c97332f 100644
--- a/net/rds/ib_send.c
+++ b/net/rds/ib_send.c
@@ -36,6 +36,7 @@
 #include <linux/dmapool.h>
 #include <linux/ratelimit.h>
 
+#include "rds_single_path.h"
 #include "rds.h"
 #include "ib.h"
 
@@ -979,8 +980,9 @@ out:
 	return ret;
 }
 
-void rds_ib_xmit_complete(struct rds_connection *conn)
+void rds_ib_xmit_path_complete(struct rds_conn_path *cp)
 {
+	struct rds_connection *conn = cp->cp_conn;
 	struct rds_ib_connection *ic = conn->c_transport_data;
 
 	/* We may have a pending ACK or window update we were unable
diff --git a/net/rds/loop.c b/net/rds/loop.c
index 814173b466d9..f2bf78de5688 100644
--- a/net/rds/loop.c
+++ b/net/rds/loop.c
@@ -34,6 +34,7 @@
 #include <linux/slab.h>
 #include <linux/in.h>
 
+#include "rds_single_path.h"
 #include "rds.h"
 #include "loop.h"
 
@@ -101,7 +102,7 @@ static void rds_loop_inc_free(struct rds_incoming *inc)
 }
 
 /* we need to at least give the thread something to succeed */
-static int rds_loop_recv(struct rds_connection *conn)
+static int rds_loop_recv_path(struct rds_conn_path *cp)
 {
 	return 0;
 }
@@ -149,13 +150,13 @@ static void rds_loop_conn_free(void *arg)
 	kfree(lc);
 }
 
-static int rds_loop_conn_connect(struct rds_connection *conn)
+static int rds_loop_conn_path_connect(struct rds_conn_path *cp)
 {
-	rds_connect_complete(conn);
+	rds_connect_complete(cp->cp_conn);
 	return 0;
 }
 
-static void rds_loop_conn_shutdown(struct rds_connection *conn)
+static void rds_loop_conn_path_shutdown(struct rds_conn_path *cp)
 {
 }
 
@@ -184,11 +185,11 @@ void rds_loop_exit(void)
  */
 struct rds_transport rds_loop_transport = {
 	.xmit			= rds_loop_xmit,
-	.recv			= rds_loop_recv,
+	.recv_path		= rds_loop_recv_path,
 	.conn_alloc		= rds_loop_conn_alloc,
 	.conn_free		= rds_loop_conn_free,
-	.conn_connect		= rds_loop_conn_connect,
-	.conn_shutdown		= rds_loop_conn_shutdown,
+	.conn_path_connect	= rds_loop_conn_path_connect,
+	.conn_path_shutdown	= rds_loop_conn_path_shutdown,
 	.inc_copy_to_user	= rds_message_inc_copy_to_user,
 	.inc_free		= rds_loop_inc_free,
 	.t_name			= "loopback",
diff --git a/net/rds/message.c b/net/rds/message.c
index 756c73729126..6cb91061556a 100644
--- a/net/rds/message.c
+++ b/net/rds/message.c
@@ -41,6 +41,7 @@ static unsigned int	rds_exthdr_size[__RDS_EXTHDR_MAX] = {
 [RDS_EXTHDR_VERSION]	= sizeof(struct rds_ext_header_version),
 [RDS_EXTHDR_RDMA]	= sizeof(struct rds_ext_header_rdma),
 [RDS_EXTHDR_RDMA_DEST]	= sizeof(struct rds_ext_header_rdma_dest),
+[RDS_EXTHDR_NPATHS]	= sizeof(u16),
 };
 
 
diff --git a/net/rds/rdma_transport.c b/net/rds/rdma_transport.c
index 7220bebcf558..345f09059e9f 100644
--- a/net/rds/rdma_transport.c
+++ b/net/rds/rdma_transport.c
@@ -33,6 +33,7 @@
 #include <linux/module.h>
 #include <rdma/rdma_cm.h>
 
+#include "rds_single_path.h"
 #include "rdma_transport.h"
 #include "ib.h"
 
diff --git a/net/rds/rds.h b/net/rds/rds.h
index 387df5f32e49..b2d17f0fafa8 100644
--- a/net/rds/rds.h
+++ b/net/rds/rds.h
@@ -84,56 +84,73 @@ enum {
 #define RDS_IN_XMIT		2
 #define RDS_RECV_REFILL		3
 
+/* Max number of multipaths per RDS connection. Must be a power of 2 */
+#define	RDS_MPATH_WORKERS	8
+#define	RDS_MPATH_HASH(rs, n) (jhash_1word((rs)->rs_bound_port, \
+			       (rs)->rs_hash_initval) & ((n) - 1))
+
+/* Per mpath connection state */
+struct rds_conn_path {
+	struct rds_connection	*cp_conn;
+	struct rds_message	*cp_xmit_rm;
+	unsigned long		cp_xmit_sg;
+	unsigned int		cp_xmit_hdr_off;
+	unsigned int		cp_xmit_data_off;
+	unsigned int		cp_xmit_atomic_sent;
+	unsigned int		cp_xmit_rdma_sent;
+	unsigned int		cp_xmit_data_sent;
+
+	spinlock_t		cp_lock;		/* protect msg queues */
+	u64			cp_next_tx_seq;
+	struct list_head	cp_send_queue;
+	struct list_head	cp_retrans;
+
+	u64			cp_next_rx_seq;
+
+	void			*cp_transport_data;
+
+	atomic_t		cp_state;
+	unsigned long		cp_send_gen;
+	unsigned long		cp_flags;
+	unsigned long		cp_reconnect_jiffies;
+	struct delayed_work	cp_send_w;
+	struct delayed_work	cp_recv_w;
+	struct delayed_work	cp_conn_w;
+	struct work_struct	cp_down_w;
+	struct mutex		cp_cm_lock;	/* protect cp_state & cm */
+	wait_queue_head_t	cp_waitq;
+
+	unsigned int		cp_unacked_packets;
+	unsigned int		cp_unacked_bytes;
+	unsigned int		cp_outgoing:1,
+				cp_pad_to_32:31;
+	unsigned int		cp_index;
+};
+
+/* One rds_connection per RDS address pair */
 struct rds_connection {
 	struct hlist_node	c_hash_node;
 	__be32			c_laddr;
 	__be32			c_faddr;
 	unsigned int		c_loopback:1,
-				c_outgoing:1,
+				c_ping_triggered:1,
 				c_pad_to_32:30;
+	int			c_npaths;
 	struct rds_connection	*c_passive;
+	struct rds_transport	*c_trans;
 
 	struct rds_cong_map	*c_lcong;
 	struct rds_cong_map	*c_fcong;
 
-	struct rds_message	*c_xmit_rm;
-	unsigned long		c_xmit_sg;
-	unsigned int		c_xmit_hdr_off;
-	unsigned int		c_xmit_data_off;
-	unsigned int		c_xmit_atomic_sent;
-	unsigned int		c_xmit_rdma_sent;
-	unsigned int		c_xmit_data_sent;
-
-	spinlock_t		c_lock;		/* protect msg queues */
-	u64			c_next_tx_seq;
-	struct list_head	c_send_queue;
-	struct list_head	c_retrans;
-
-	u64			c_next_rx_seq;
-
-	struct rds_transport	*c_trans;
-	void			*c_transport_data;
-
-	atomic_t		c_state;
-	unsigned long		c_send_gen;
-	unsigned long		c_flags;
-	unsigned long		c_reconnect_jiffies;
-	struct delayed_work	c_send_w;
-	struct delayed_work	c_recv_w;
-	struct delayed_work	c_conn_w;
-	struct work_struct	c_down_w;
-	struct mutex		c_cm_lock;	/* protect conn state & cm */
-	wait_queue_head_t	c_waitq;
+	/* Protocol version */
+	unsigned int		c_version;
+	possible_net_t		c_net;
 
 	struct list_head	c_map_item;
 	unsigned long		c_map_queued;
 
-	unsigned int		c_unacked_packets;
-	unsigned int		c_unacked_bytes;
-
-	/* Protocol version */
-	unsigned int		c_version;
-	possible_net_t		c_net;
+	struct rds_conn_path	c_path[RDS_MPATH_WORKERS];
+	wait_queue_head_t	c_hs_waitq; /* handshake waitq */
 };
 
 static inline
@@ -153,6 +170,17 @@ void rds_conn_net_set(struct rds_connection *conn, struct net *net)
 #define RDS_FLAG_RETRANSMITTED	0x04
 #define RDS_MAX_ADV_CREDIT	255
 
+/* RDS_FLAG_PROBE_PORT is the reserved sport used for sending a ping
+ * probe to exchange control information before establishing a connection.
+ * Currently the control information that is exchanged is the number of
+ * supported paths. If the peer is a legacy (older kernel revision) peer,
+ * it would return a pong message without additional control information
+ * that would then alert the sender that the peer was an older rev.
+ */
+#define RDS_FLAG_PROBE_PORT	1
+#define	RDS_HS_PROBE(sport, dport) \
+		((sport == RDS_FLAG_PROBE_PORT && dport == 0) || \
+		 (sport == 0 && dport == RDS_FLAG_PROBE_PORT))
 /*
  * Maximum space available for extension headers.
  */
@@ -212,12 +240,18 @@ struct rds_ext_header_rdma_dest {
 	__be32			h_rdma_offset;
 };
 
+/* Extension header announcing number of paths.
+ * Implicit length = 2 bytes.
+ */
+#define RDS_EXTHDR_NPATHS	4
+
 #define __RDS_EXTHDR_MAX	16 /* for now */
 
 struct rds_incoming {
 	atomic_t		i_refcount;
 	struct list_head	i_item;
 	struct rds_connection	*i_conn;
+	struct rds_conn_path	*i_conn_path;
 	struct rds_header	i_hdr;
 	unsigned long		i_rx_jiffies;
 	__be32			i_saddr;
@@ -433,21 +467,22 @@ struct rds_transport {
 	char			t_name[TRANSNAMSIZ];
 	struct list_head	t_item;
 	struct module		*t_owner;
-	unsigned int		t_prefer_loopback:1;
+	unsigned int		t_prefer_loopback:1,
+				t_mp_capable:1;
 	unsigned int		t_type;
 
 	int (*laddr_check)(struct net *net, __be32 addr);
 	int (*conn_alloc)(struct rds_connection *conn, gfp_t gfp);
 	void (*conn_free)(void *data);
-	int (*conn_connect)(struct rds_connection *conn);
-	void (*conn_shutdown)(struct rds_connection *conn);
-	void (*xmit_prepare)(struct rds_connection *conn);
-	void (*xmit_complete)(struct rds_connection *conn);
+	int (*conn_path_connect)(struct rds_conn_path *cp);
+	void (*conn_path_shutdown)(struct rds_conn_path *conn);
+	void (*xmit_path_prepare)(struct rds_conn_path *cp);
+	void (*xmit_path_complete)(struct rds_conn_path *cp);
 	int (*xmit)(struct rds_connection *conn, struct rds_message *rm,
 		    unsigned int hdr_off, unsigned int sg, unsigned int off);
 	int (*xmit_rdma)(struct rds_connection *conn, struct rm_rdma_op *op);
 	int (*xmit_atomic)(struct rds_connection *conn, struct rm_atomic_op *op);
-	int (*recv)(struct rds_connection *conn);
+	int (*recv_path)(struct rds_conn_path *cp);
 	int (*inc_copy_to_user)(struct rds_incoming *inc, struct iov_iter *to);
 	void (*inc_free)(struct rds_incoming *inc);
 
@@ -530,6 +565,7 @@ struct rds_sock {
 	/* Socket options - in case there will be more */
 	unsigned char		rs_recverr,
 				rs_cong_monitor;
+	u32			rs_hash_initval;
 };
 
 static inline struct rds_sock *rds_sk_to_rs(const struct sock *sk)
@@ -636,10 +672,12 @@ struct rds_connection *rds_conn_create(struct net *net,
 struct rds_connection *rds_conn_create_outgoing(struct net *net,
 						__be32 laddr, __be32 faddr,
 			       struct rds_transport *trans, gfp_t gfp);
-void rds_conn_shutdown(struct rds_connection *conn);
+void rds_conn_shutdown(struct rds_conn_path *cpath);
 void rds_conn_destroy(struct rds_connection *conn);
 void rds_conn_drop(struct rds_connection *conn);
+void rds_conn_path_drop(struct rds_conn_path *cpath);
 void rds_conn_connect_if_down(struct rds_connection *conn);
+void rds_conn_path_connect_if_down(struct rds_conn_path *cp);
 void rds_for_each_conn_info(struct socket *sock, unsigned int len,
 			  struct rds_info_iterator *iter,
 			  struct rds_info_lengths *lens,
@@ -650,28 +688,60 @@ void __rds_conn_error(struct rds_connection *conn, const char *, ...);
 #define rds_conn_error(conn, fmt...) \
 	__rds_conn_error(conn, KERN_WARNING "RDS: " fmt)
 
+void __rds_conn_path_error(struct rds_conn_path *cp, const char *, ...);
+#define rds_conn_path_error(cp, fmt...) \
+	__rds_conn_path_error(cp, KERN_WARNING "RDS: " fmt)
+
+static inline int
+rds_conn_path_transition(struct rds_conn_path *cp, int old, int new)
+{
+	return atomic_cmpxchg(&cp->cp_state, old, new) == old;
+}
+
 static inline int
 rds_conn_transition(struct rds_connection *conn, int old, int new)
 {
-	return atomic_cmpxchg(&conn->c_state, old, new) == old;
+	WARN_ON(conn->c_trans->t_mp_capable);
+	return rds_conn_path_transition(&conn->c_path[0], old, new);
+}
+
+static inline int
+rds_conn_path_state(struct rds_conn_path *cp)
+{
+	return atomic_read(&cp->cp_state);
 }
 
 static inline int
 rds_conn_state(struct rds_connection *conn)
 {
-	return atomic_read(&conn->c_state);
+	WARN_ON(conn->c_trans->t_mp_capable);
+	return rds_conn_path_state(&conn->c_path[0]);
+}
+
+static inline int
+rds_conn_path_up(struct rds_conn_path *cp)
+{
+	return atomic_read(&cp->cp_state) == RDS_CONN_UP;
 }
 
 static inline int
 rds_conn_up(struct rds_connection *conn)
 {
-	return atomic_read(&conn->c_state) == RDS_CONN_UP;
+	WARN_ON(conn->c_trans->t_mp_capable);
+	return rds_conn_path_up(&conn->c_path[0]);
+}
+
+static inline int
+rds_conn_path_connecting(struct rds_conn_path *cp)
+{
+	return atomic_read(&cp->cp_state) == RDS_CONN_CONNECTING;
 }
 
 static inline int
 rds_conn_connecting(struct rds_connection *conn)
 {
-	return atomic_read(&conn->c_state) == RDS_CONN_CONNECTING;
+	WARN_ON(conn->c_trans->t_mp_capable);
+	return rds_conn_path_connecting(&conn->c_path[0]);
 }
 
 /* message.c */
@@ -720,6 +790,8 @@ void rds_page_exit(void);
 /* recv.c */
 void rds_inc_init(struct rds_incoming *inc, struct rds_connection *conn,
 		  __be32 saddr);
+void rds_inc_path_init(struct rds_incoming *inc, struct rds_conn_path *conn,
+		       __be32 saddr);
 void rds_inc_put(struct rds_incoming *inc);
 void rds_recv_incoming(struct rds_connection *conn, __be32 saddr, __be32 daddr,
 		       struct rds_incoming *inc, gfp_t gfp);
@@ -733,16 +805,16 @@ void rds_inc_info_copy(struct rds_incoming *inc,
 
 /* send.c */
 int rds_sendmsg(struct socket *sock, struct msghdr *msg, size_t payload_len);
-void rds_send_reset(struct rds_connection *conn);
-int rds_send_xmit(struct rds_connection *conn);
+void rds_send_path_reset(struct rds_conn_path *conn);
+int rds_send_xmit(struct rds_conn_path *cp);
 struct sockaddr_in;
 void rds_send_drop_to(struct rds_sock *rs, struct sockaddr_in *dest);
 typedef int (*is_acked_func)(struct rds_message *rm, uint64_t ack);
 void rds_send_drop_acked(struct rds_connection *conn, u64 ack,
 			 is_acked_func is_acked);
-int rds_send_pong(struct rds_connection *conn, __be16 dport);
-struct rds_message *rds_send_get_message(struct rds_connection *,
-					 struct rm_rdma_op *);
+void rds_send_path_drop_acked(struct rds_conn_path *cp, u64 ack,
+			      is_acked_func is_acked);
+int rds_send_pong(struct rds_conn_path *cp, __be16 dport);
 
 /* rdma.c */
 void rds_rdma_unuse(struct rds_sock *rs, u32 r_key, int force);
@@ -809,12 +881,12 @@ extern unsigned int  rds_sysctl_trace_level;
 int rds_threads_init(void);
 void rds_threads_exit(void);
 extern struct workqueue_struct *rds_wq;
-void rds_queue_reconnect(struct rds_connection *conn);
+void rds_queue_reconnect(struct rds_conn_path *cp);
 void rds_connect_worker(struct work_struct *);
 void rds_shutdown_worker(struct work_struct *);
 void rds_send_worker(struct work_struct *);
 void rds_recv_worker(struct work_struct *);
-void rds_connect_path_complete(struct rds_connection *conn, int curr);
+void rds_connect_path_complete(struct rds_conn_path *conn, int curr);
 void rds_connect_complete(struct rds_connection *conn);
 
 /* transport.c */
diff --git a/net/rds/rds_single_path.h b/net/rds/rds_single_path.h
new file mode 100644
index 000000000000..e1241af7c1ad
--- /dev/null
+++ b/net/rds/rds_single_path.h
@@ -0,0 +1,30 @@
+#ifndef _RDS_RDS_SINGLE_H
+#define _RDS_RDS_SINGLE_H
+
+#define	c_xmit_rm		c_path[0].cp_xmit_rm
+#define	c_xmit_sg		c_path[0].cp_xmit_sg
+#define	c_xmit_hdr_off		c_path[0].cp_xmit_hdr_off
+#define	c_xmit_data_off		c_path[0].cp_xmit_data_off
+#define	c_xmit_atomic_sent	c_path[0].cp_xmit_atomic_sent
+#define	c_xmit_rdma_sent	c_path[0].cp_xmit_rdma_sent
+#define	c_xmit_data_sent	c_path[0].cp_xmit_data_sent
+#define	c_lock			c_path[0].cp_lock
+#define c_next_tx_seq		c_path[0].cp_next_tx_seq
+#define c_send_queue		c_path[0].cp_send_queue
+#define c_retrans		c_path[0].cp_retrans
+#define c_next_rx_seq		c_path[0].cp_next_rx_seq
+#define c_transport_data	c_path[0].cp_transport_data
+#define c_state			c_path[0].cp_state
+#define c_send_gen		c_path[0].cp_send_gen
+#define c_flags			c_path[0].cp_flags
+#define c_reconnect_jiffies	c_path[0].cp_reconnect_jiffies
+#define c_send_w		c_path[0].cp_send_w
+#define c_recv_w		c_path[0].cp_recv_w
+#define c_conn_w		c_path[0].cp_conn_w
+#define c_down_w		c_path[0].cp_down_w
+#define c_cm_lock		c_path[0].cp_cm_lock
+#define c_waitq			c_path[0].cp_waitq
+#define c_unacked_packets	c_path[0].cp_unacked_packets
+#define c_unacked_bytes		c_path[0].cp_unacked_bytes
+
+#endif /* _RDS_RDS_SINGLE_H */
diff --git a/net/rds/recv.c b/net/rds/recv.c
index 8413f6c99e13..cbfabdf3ff48 100644
--- a/net/rds/recv.c
+++ b/net/rds/recv.c
@@ -53,6 +53,20 @@ void rds_inc_init(struct rds_incoming *inc, struct rds_connection *conn,
 }
 EXPORT_SYMBOL_GPL(rds_inc_init);
 
+void rds_inc_path_init(struct rds_incoming *inc, struct rds_conn_path *cp,
+		       __be32 saddr)
+{
+	atomic_set(&inc->i_refcount, 1);
+	INIT_LIST_HEAD(&inc->i_item);
+	inc->i_conn = cp->cp_conn;
+	inc->i_conn_path = cp;
+	inc->i_saddr = saddr;
+	inc->i_rdma_cookie = 0;
+	inc->i_rx_tstamp.tv_sec = 0;
+	inc->i_rx_tstamp.tv_usec = 0;
+}
+EXPORT_SYMBOL_GPL(rds_inc_path_init);
+
 static void rds_inc_addref(struct rds_incoming *inc)
 {
 	rdsdebug("addref inc %p ref %d\n", inc, atomic_read(&inc->i_refcount));
@@ -142,6 +156,67 @@ static void rds_recv_incoming_exthdrs(struct rds_incoming *inc, struct rds_sock
 	}
 }
 
+static void rds_recv_hs_exthdrs(struct rds_header *hdr,
+				struct rds_connection *conn)
+{
+	unsigned int pos = 0, type, len;
+	union {
+		struct rds_ext_header_version version;
+		u16 rds_npaths;
+	} buffer;
+
+	while (1) {
+		len = sizeof(buffer);
+		type = rds_message_next_extension(hdr, &pos, &buffer, &len);
+		if (type == RDS_EXTHDR_NONE)
+			break;
+		/* Process extension header here */
+		switch (type) {
+		case RDS_EXTHDR_NPATHS:
+			conn->c_npaths = min_t(int, RDS_MPATH_WORKERS,
+					       buffer.rds_npaths);
+			break;
+		default:
+			pr_warn_ratelimited("ignoring unknown exthdr type "
+					     "0x%x\n", type);
+		}
+	}
+	/* if RDS_EXTHDR_NPATHS was not found, default to a single-path */
+	conn->c_npaths = max_t(int, conn->c_npaths, 1);
+}
+
+/* rds_start_mprds() will synchronously start multiple paths when appropriate.
+ * The scheme is based on the following rules:
+ *
+ * 1. rds_sendmsg on first connect attempt sends the probe ping, with the
+ *    sender's npaths (s_npaths)
+ * 2. rcvr of probe-ping knows the mprds_paths = min(s_npaths, r_npaths). It
+ *    sends back a probe-pong with r_npaths. After that, if rcvr is the
+ *    smaller ip addr, it starts rds_conn_path_connect_if_down on all
+ *    mprds_paths.
+ * 3. sender gets woken up, and can move to rds_conn_path_connect_if_down.
+ *    If it is the smaller ipaddr, rds_conn_path_connect_if_down can be
+ *    called after reception of the probe-pong on all mprds_paths.
+ *    Otherwise (sender of probe-ping is not the smaller ip addr): just call
+ *    rds_conn_path_connect_if_down on the hashed path. (see rule 4)
+ * 4. when cp_index > 0, rds_connect_worker must only trigger
+ *    a connection if laddr < faddr.
+ * 5. sender may end up queuing the packet on the cp. will get sent out later.
+ *    when connection is completed.
+ */
+static void rds_start_mprds(struct rds_connection *conn)
+{
+	int i;
+	struct rds_conn_path *cp;
+
+	if (conn->c_npaths > 1 && conn->c_laddr < conn->c_faddr) {
+		for (i = 1; i < conn->c_npaths; i++) {
+			cp = &conn->c_path[i];
+			rds_conn_path_connect_if_down(cp);
+		}
+	}
+}
+
 /*
  * The transport must make sure that this is serialized against other
  * rx and conn reset on this specific conn.
@@ -164,13 +239,18 @@ void rds_recv_incoming(struct rds_connection *conn, __be32 saddr, __be32 daddr,
 	struct rds_sock *rs = NULL;
 	struct sock *sk;
 	unsigned long flags;
+	struct rds_conn_path *cp;
 
 	inc->i_conn = conn;
 	inc->i_rx_jiffies = jiffies;
+	if (conn->c_trans->t_mp_capable)
+		cp = inc->i_conn_path;
+	else
+		cp = &conn->c_path[0];
 
 	rdsdebug("conn %p next %llu inc %p seq %llu len %u sport %u dport %u "
 		 "flags 0x%x rx_jiffies %lu\n", conn,
-		 (unsigned long long)conn->c_next_rx_seq,
+		 (unsigned long long)cp->cp_next_rx_seq,
 		 inc,
 		 (unsigned long long)be64_to_cpu(inc->i_hdr.h_sequence),
 		 be32_to_cpu(inc->i_hdr.h_len),
@@ -199,16 +279,34 @@ void rds_recv_incoming(struct rds_connection *conn, __be32 saddr, __be32 daddr,
 	 * XXX we could spend more on the wire to get more robust failure
 	 * detection, arguably worth it to avoid data corruption.
 	 */
-	if (be64_to_cpu(inc->i_hdr.h_sequence) < conn->c_next_rx_seq &&
+	if (be64_to_cpu(inc->i_hdr.h_sequence) < cp->cp_next_rx_seq &&
 	    (inc->i_hdr.h_flags & RDS_FLAG_RETRANSMITTED)) {
 		rds_stats_inc(s_recv_drop_old_seq);
 		goto out;
 	}
-	conn->c_next_rx_seq = be64_to_cpu(inc->i_hdr.h_sequence) + 1;
+	cp->cp_next_rx_seq = be64_to_cpu(inc->i_hdr.h_sequence) + 1;
 
 	if (rds_sysctl_ping_enable && inc->i_hdr.h_dport == 0) {
+		if (inc->i_hdr.h_sport == 0) {
+			rdsdebug("ignore ping with 0 sport from 0x%x\n", saddr);
+			goto out;
+		}
 		rds_stats_inc(s_recv_ping);
-		rds_send_pong(conn, inc->i_hdr.h_sport);
+		rds_send_pong(cp, inc->i_hdr.h_sport);
+		/* if this is a handshake ping, start multipath if necessary */
+		if (RDS_HS_PROBE(inc->i_hdr.h_sport, inc->i_hdr.h_dport)) {
+			rds_recv_hs_exthdrs(&inc->i_hdr, cp->cp_conn);
+			rds_start_mprds(cp->cp_conn);
+		}
+		goto out;
+	}
+
+	if (inc->i_hdr.h_dport ==  RDS_FLAG_PROBE_PORT &&
+	    inc->i_hdr.h_sport == 0) {
+		rds_recv_hs_exthdrs(&inc->i_hdr, cp->cp_conn);
+		/* if this is a handshake pong, start multipath if necessary */
+		rds_start_mprds(cp->cp_conn);
+		wake_up(&cp->cp_conn->c_hs_waitq);
 		goto out;
 	}
 
diff --git a/net/rds/send.c b/net/rds/send.c
index b1962f8e30f7..896626b9a0ef 100644
--- a/net/rds/send.c
+++ b/net/rds/send.c
@@ -62,14 +62,14 @@ static void rds_send_remove_from_sock(struct list_head *messages, int status);
  * Reset the send state.  Callers must ensure that this doesn't race with
  * rds_send_xmit().
  */
-void rds_send_reset(struct rds_connection *conn)
+void rds_send_path_reset(struct rds_conn_path *cp)
 {
 	struct rds_message *rm, *tmp;
 	unsigned long flags;
 
-	if (conn->c_xmit_rm) {
-		rm = conn->c_xmit_rm;
-		conn->c_xmit_rm = NULL;
+	if (cp->cp_xmit_rm) {
+		rm = cp->cp_xmit_rm;
+		cp->cp_xmit_rm = NULL;
 		/* Tell the user the RDMA op is no longer mapped by the
 		 * transport. This isn't entirely true (it's flushed out
 		 * independently) but as the connection is down, there's
@@ -78,37 +78,37 @@ void rds_send_reset(struct rds_connection *conn)
 		rds_message_put(rm);
 	}
 
-	conn->c_xmit_sg = 0;
-	conn->c_xmit_hdr_off = 0;
-	conn->c_xmit_data_off = 0;
-	conn->c_xmit_atomic_sent = 0;
-	conn->c_xmit_rdma_sent = 0;
-	conn->c_xmit_data_sent = 0;
+	cp->cp_xmit_sg = 0;
+	cp->cp_xmit_hdr_off = 0;
+	cp->cp_xmit_data_off = 0;
+	cp->cp_xmit_atomic_sent = 0;
+	cp->cp_xmit_rdma_sent = 0;
+	cp->cp_xmit_data_sent = 0;
 
-	conn->c_map_queued = 0;
+	cp->cp_conn->c_map_queued = 0;
 
-	conn->c_unacked_packets = rds_sysctl_max_unacked_packets;
-	conn->c_unacked_bytes = rds_sysctl_max_unacked_bytes;
+	cp->cp_unacked_packets = rds_sysctl_max_unacked_packets;
+	cp->cp_unacked_bytes = rds_sysctl_max_unacked_bytes;
 
 	/* Mark messages as retransmissions, and move them to the send q */
-	spin_lock_irqsave(&conn->c_lock, flags);
-	list_for_each_entry_safe(rm, tmp, &conn->c_retrans, m_conn_item) {
+	spin_lock_irqsave(&cp->cp_lock, flags);
+	list_for_each_entry_safe(rm, tmp, &cp->cp_retrans, m_conn_item) {
 		set_bit(RDS_MSG_ACK_REQUIRED, &rm->m_flags);
 		set_bit(RDS_MSG_RETRANSMITTED, &rm->m_flags);
 	}
-	list_splice_init(&conn->c_retrans, &conn->c_send_queue);
-	spin_unlock_irqrestore(&conn->c_lock, flags);
+	list_splice_init(&cp->cp_retrans, &cp->cp_send_queue);
+	spin_unlock_irqrestore(&cp->cp_lock, flags);
 }
-EXPORT_SYMBOL_GPL(rds_send_reset);
+EXPORT_SYMBOL_GPL(rds_send_path_reset);
 
-static int acquire_in_xmit(struct rds_connection *conn)
+static int acquire_in_xmit(struct rds_conn_path *cp)
 {
-	return test_and_set_bit(RDS_IN_XMIT, &conn->c_flags) == 0;
+	return test_and_set_bit(RDS_IN_XMIT, &cp->cp_flags) == 0;
 }
 
-static void release_in_xmit(struct rds_connection *conn)
+static void release_in_xmit(struct rds_conn_path *cp)
 {
-	clear_bit(RDS_IN_XMIT, &conn->c_flags);
+	clear_bit(RDS_IN_XMIT, &cp->cp_flags);
 	smp_mb__after_atomic();
 	/*
 	 * We don't use wait_on_bit()/wake_up_bit() because our waking is in a
@@ -116,8 +116,8 @@ static void release_in_xmit(struct rds_connection *conn)
 	 * the system-wide hashed waitqueue buckets in the fast path only to
 	 * almost never find waiters.
 	 */
-	if (waitqueue_active(&conn->c_waitq))
-		wake_up_all(&conn->c_waitq);
+	if (waitqueue_active(&cp->cp_waitq))
+		wake_up_all(&cp->cp_waitq);
 }
 
 /*
@@ -134,8 +134,9 @@ static void release_in_xmit(struct rds_connection *conn)
  *      - small message latency is higher behind queued large messages
  *      - large message latency isn't starved by intervening small sends
  */
-int rds_send_xmit(struct rds_connection *conn)
+int rds_send_xmit(struct rds_conn_path *cp)
 {
+	struct rds_connection *conn = cp->cp_conn;
 	struct rds_message *rm;
 	unsigned long flags;
 	unsigned int tmp;
@@ -155,7 +156,7 @@ restart:
 	 * avoids blocking the caller and trading per-connection data between
 	 * caches per message.
 	 */
-	if (!acquire_in_xmit(conn)) {
+	if (!acquire_in_xmit(cp)) {
 		rds_stats_inc(s_send_lock_contention);
 		ret = -ENOMEM;
 		goto out;
@@ -169,21 +170,21 @@ restart:
 	 * The acquire_in_xmit() check above ensures that only one
 	 * caller can increment c_send_gen at any time.
 	 */
-	conn->c_send_gen++;
-	send_gen = conn->c_send_gen;
+	cp->cp_send_gen++;
+	send_gen = cp->cp_send_gen;
 
 	/*
 	 * rds_conn_shutdown() sets the conn state and then tests RDS_IN_XMIT,
 	 * we do the opposite to avoid races.
 	 */
-	if (!rds_conn_up(conn)) {
-		release_in_xmit(conn);
+	if (!rds_conn_path_up(cp)) {
+		release_in_xmit(cp);
 		ret = 0;
 		goto out;
 	}
 
-	if (conn->c_trans->xmit_prepare)
-		conn->c_trans->xmit_prepare(conn);
+	if (conn->c_trans->xmit_path_prepare)
+		conn->c_trans->xmit_path_prepare(cp);
 
 	/*
 	 * spin trying to push headers and data down the connection until
@@ -191,7 +192,7 @@ restart:
 	 */
 	while (1) {
 
-		rm = conn->c_xmit_rm;
+		rm = cp->cp_xmit_rm;
 
 		/*
 		 * If between sending messages, we can send a pending congestion
@@ -204,14 +205,16 @@ restart:
 				break;
 			}
 			rm->data.op_active = 1;
+			rm->m_inc.i_conn_path = cp;
+			rm->m_inc.i_conn = cp->cp_conn;
 
-			conn->c_xmit_rm = rm;
+			cp->cp_xmit_rm = rm;
 		}
 
 		/*
 		 * If not already working on one, grab the next message.
 		 *
-		 * c_xmit_rm holds a ref while we're sending this message down
+		 * cp_xmit_rm holds a ref while we're sending this message down
 		 * the connction.  We can use this ref while holding the
 		 * send_sem.. rds_send_reset() is serialized with it.
 		 */
@@ -228,10 +231,10 @@ restart:
 			if (batch_count >= send_batch_count)
 				goto over_batch;
 
-			spin_lock_irqsave(&conn->c_lock, flags);
+			spin_lock_irqsave(&cp->cp_lock, flags);
 
-			if (!list_empty(&conn->c_send_queue)) {
-				rm = list_entry(conn->c_send_queue.next,
+			if (!list_empty(&cp->cp_send_queue)) {
+				rm = list_entry(cp->cp_send_queue.next,
 						struct rds_message,
 						m_conn_item);
 				rds_message_addref(rm);
@@ -240,10 +243,11 @@ restart:
 				 * Move the message from the send queue to the retransmit
 				 * list right away.
 				 */
-				list_move_tail(&rm->m_conn_item, &conn->c_retrans);
+				list_move_tail(&rm->m_conn_item,
+					       &cp->cp_retrans);
 			}
 
-			spin_unlock_irqrestore(&conn->c_lock, flags);
+			spin_unlock_irqrestore(&cp->cp_lock, flags);
 
 			if (!rm)
 				break;
@@ -257,32 +261,34 @@ restart:
 			 */
 			if (rm->rdma.op_active &&
 			    test_bit(RDS_MSG_RETRANSMITTED, &rm->m_flags)) {
-				spin_lock_irqsave(&conn->c_lock, flags);
+				spin_lock_irqsave(&cp->cp_lock, flags);
 				if (test_and_clear_bit(RDS_MSG_ON_CONN, &rm->m_flags))
 					list_move(&rm->m_conn_item, &to_be_dropped);
-				spin_unlock_irqrestore(&conn->c_lock, flags);
+				spin_unlock_irqrestore(&cp->cp_lock, flags);
 				continue;
 			}
 
 			/* Require an ACK every once in a while */
 			len = ntohl(rm->m_inc.i_hdr.h_len);
-			if (conn->c_unacked_packets == 0 ||
-			    conn->c_unacked_bytes < len) {
+			if (cp->cp_unacked_packets == 0 ||
+			    cp->cp_unacked_bytes < len) {
 				__set_bit(RDS_MSG_ACK_REQUIRED, &rm->m_flags);
 
-				conn->c_unacked_packets = rds_sysctl_max_unacked_packets;
-				conn->c_unacked_bytes = rds_sysctl_max_unacked_bytes;
+				cp->cp_unacked_packets =
+					rds_sysctl_max_unacked_packets;
+				cp->cp_unacked_bytes =
+					rds_sysctl_max_unacked_bytes;
 				rds_stats_inc(s_send_ack_required);
 			} else {
-				conn->c_unacked_bytes -= len;
-				conn->c_unacked_packets--;
+				cp->cp_unacked_bytes -= len;
+				cp->cp_unacked_packets--;
 			}
 
-			conn->c_xmit_rm = rm;
+			cp->cp_xmit_rm = rm;
 		}
 
 		/* The transport either sends the whole rdma or none of it */
-		if (rm->rdma.op_active && !conn->c_xmit_rdma_sent) {
+		if (rm->rdma.op_active && !cp->cp_xmit_rdma_sent) {
 			rm->m_final_op = &rm->rdma;
 			/* The transport owns the mapped memory for now.
 			 * You can't unmap it while it's on the send queue
@@ -294,11 +300,11 @@ restart:
 				wake_up_interruptible(&rm->m_flush_wait);
 				break;
 			}
-			conn->c_xmit_rdma_sent = 1;
+			cp->cp_xmit_rdma_sent = 1;
 
 		}
 
-		if (rm->atomic.op_active && !conn->c_xmit_atomic_sent) {
+		if (rm->atomic.op_active && !cp->cp_xmit_atomic_sent) {
 			rm->m_final_op = &rm->atomic;
 			/* The transport owns the mapped memory for now.
 			 * You can't unmap it while it's on the send queue
@@ -310,7 +316,7 @@ restart:
 				wake_up_interruptible(&rm->m_flush_wait);
 				break;
 			}
-			conn->c_xmit_atomic_sent = 1;
+			cp->cp_xmit_atomic_sent = 1;
 
 		}
 
@@ -336,41 +342,42 @@ restart:
 				rm->data.op_active = 0;
 		}
 
-		if (rm->data.op_active && !conn->c_xmit_data_sent) {
+		if (rm->data.op_active && !cp->cp_xmit_data_sent) {
 			rm->m_final_op = &rm->data;
+
 			ret = conn->c_trans->xmit(conn, rm,
-						  conn->c_xmit_hdr_off,
-						  conn->c_xmit_sg,
-						  conn->c_xmit_data_off);
+						  cp->cp_xmit_hdr_off,
+						  cp->cp_xmit_sg,
+						  cp->cp_xmit_data_off);
 			if (ret <= 0)
 				break;
 
-			if (conn->c_xmit_hdr_off < sizeof(struct rds_header)) {
+			if (cp->cp_xmit_hdr_off < sizeof(struct rds_header)) {
 				tmp = min_t(int, ret,
 					    sizeof(struct rds_header) -
-					    conn->c_xmit_hdr_off);
-				conn->c_xmit_hdr_off += tmp;
+					    cp->cp_xmit_hdr_off);
+				cp->cp_xmit_hdr_off += tmp;
 				ret -= tmp;
 			}
 
-			sg = &rm->data.op_sg[conn->c_xmit_sg];
+			sg = &rm->data.op_sg[cp->cp_xmit_sg];
 			while (ret) {
 				tmp = min_t(int, ret, sg->length -
-						      conn->c_xmit_data_off);
-				conn->c_xmit_data_off += tmp;
+						      cp->cp_xmit_data_off);
+				cp->cp_xmit_data_off += tmp;
 				ret -= tmp;
-				if (conn->c_xmit_data_off == sg->length) {
-					conn->c_xmit_data_off = 0;
+				if (cp->cp_xmit_data_off == sg->length) {
+					cp->cp_xmit_data_off = 0;
 					sg++;
-					conn->c_xmit_sg++;
-					BUG_ON(ret != 0 &&
-					       conn->c_xmit_sg == rm->data.op_nents);
+					cp->cp_xmit_sg++;
+					BUG_ON(ret != 0 && cp->cp_xmit_sg ==
+					       rm->data.op_nents);
 				}
 			}
 
-			if (conn->c_xmit_hdr_off == sizeof(struct rds_header) &&
-			    (conn->c_xmit_sg == rm->data.op_nents))
-				conn->c_xmit_data_sent = 1;
+			if (cp->cp_xmit_hdr_off == sizeof(struct rds_header) &&
+			    (cp->cp_xmit_sg == rm->data.op_nents))
+				cp->cp_xmit_data_sent = 1;
 		}
 
 		/*
@@ -378,23 +385,23 @@ restart:
 		 * if there is a data op. Thus, if the data is sent (or there was
 		 * none), then we're done with the rm.
 		 */
-		if (!rm->data.op_active || conn->c_xmit_data_sent) {
-			conn->c_xmit_rm = NULL;
-			conn->c_xmit_sg = 0;
-			conn->c_xmit_hdr_off = 0;
-			conn->c_xmit_data_off = 0;
-			conn->c_xmit_rdma_sent = 0;
-			conn->c_xmit_atomic_sent = 0;
-			conn->c_xmit_data_sent = 0;
+		if (!rm->data.op_active || cp->cp_xmit_data_sent) {
+			cp->cp_xmit_rm = NULL;
+			cp->cp_xmit_sg = 0;
+			cp->cp_xmit_hdr_off = 0;
+			cp->cp_xmit_data_off = 0;
+			cp->cp_xmit_rdma_sent = 0;
+			cp->cp_xmit_atomic_sent = 0;
+			cp->cp_xmit_data_sent = 0;
 
 			rds_message_put(rm);
 		}
 	}
 
 over_batch:
-	if (conn->c_trans->xmit_complete)
-		conn->c_trans->xmit_complete(conn);
-	release_in_xmit(conn);
+	if (conn->c_trans->xmit_path_complete)
+		conn->c_trans->xmit_path_complete(cp);
+	release_in_xmit(cp);
 
 	/* Nuke any messages we decided not to retransmit. */
 	if (!list_empty(&to_be_dropped)) {
@@ -422,12 +429,12 @@ over_batch:
 	if (ret == 0) {
 		smp_mb();
 		if ((test_bit(0, &conn->c_map_queued) ||
-		     !list_empty(&conn->c_send_queue)) &&
-		    send_gen == conn->c_send_gen) {
+		     !list_empty(&cp->cp_send_queue)) &&
+		    send_gen == cp->cp_send_gen) {
 			rds_stats_inc(s_send_lock_queue_raced);
 			if (batch_count < send_batch_count)
 				goto restart;
-			queue_delayed_work(rds_wq, &conn->c_send_w, 1);
+			queue_delayed_work(rds_wq, &cp->cp_send_w, 1);
 		}
 	}
 out:
@@ -560,42 +567,6 @@ __rds_send_complete(struct rds_sock *rs, struct rds_message *rm, int status)
 }
 
 /*
- * This is called from the IB send completion when we detect
- * a RDMA operation that failed with remote access error.
- * So speed is not an issue here.
- */
-struct rds_message *rds_send_get_message(struct rds_connection *conn,
-					 struct rm_rdma_op *op)
-{
-	struct rds_message *rm, *tmp, *found = NULL;
-	unsigned long flags;
-
-	spin_lock_irqsave(&conn->c_lock, flags);
-
-	list_for_each_entry_safe(rm, tmp, &conn->c_retrans, m_conn_item) {
-		if (&rm->rdma == op) {
-			atomic_inc(&rm->m_refcount);
-			found = rm;
-			goto out;
-		}
-	}
-
-	list_for_each_entry_safe(rm, tmp, &conn->c_send_queue, m_conn_item) {
-		if (&rm->rdma == op) {
-			atomic_inc(&rm->m_refcount);
-			found = rm;
-			break;
-		}
-	}
-
-out:
-	spin_unlock_irqrestore(&conn->c_lock, flags);
-
-	return found;
-}
-EXPORT_SYMBOL_GPL(rds_send_get_message);
-
-/*
  * This removes messages from the socket's list if they're on it.  The list
  * argument must be private to the caller, we must be able to modify it
  * without locks.  The messages must have a reference held for their
@@ -685,16 +656,16 @@ unlock_and_drop:
  * assigned the m_ack_seq yet - but that's fine as long as tcp_is_acked
  * checks the RDS_MSG_HAS_ACK_SEQ bit.
  */
-void rds_send_drop_acked(struct rds_connection *conn, u64 ack,
-			 is_acked_func is_acked)
+void rds_send_path_drop_acked(struct rds_conn_path *cp, u64 ack,
+			      is_acked_func is_acked)
 {
 	struct rds_message *rm, *tmp;
 	unsigned long flags;
 	LIST_HEAD(list);
 
-	spin_lock_irqsave(&conn->c_lock, flags);
+	spin_lock_irqsave(&cp->cp_lock, flags);
 
-	list_for_each_entry_safe(rm, tmp, &conn->c_retrans, m_conn_item) {
+	list_for_each_entry_safe(rm, tmp, &cp->cp_retrans, m_conn_item) {
 		if (!rds_send_is_acked(rm, ack, is_acked))
 			break;
 
@@ -706,17 +677,26 @@ void rds_send_drop_acked(struct rds_connection *conn, u64 ack,
 	if (!list_empty(&list))
 		smp_mb__after_atomic();
 
-	spin_unlock_irqrestore(&conn->c_lock, flags);
+	spin_unlock_irqrestore(&cp->cp_lock, flags);
 
 	/* now remove the messages from the sock list as needed */
 	rds_send_remove_from_sock(&list, RDS_RDMA_SUCCESS);
 }
+EXPORT_SYMBOL_GPL(rds_send_path_drop_acked);
+
+void rds_send_drop_acked(struct rds_connection *conn, u64 ack,
+			 is_acked_func is_acked)
+{
+	WARN_ON(conn->c_trans->t_mp_capable);
+	rds_send_path_drop_acked(&conn->c_path[0], ack, is_acked);
+}
 EXPORT_SYMBOL_GPL(rds_send_drop_acked);
 
 void rds_send_drop_to(struct rds_sock *rs, struct sockaddr_in *dest)
 {
 	struct rds_message *rm, *tmp;
 	struct rds_connection *conn;
+	struct rds_conn_path *cp;
 	unsigned long flags;
 	LIST_HEAD(list);
 
@@ -745,22 +725,26 @@ void rds_send_drop_to(struct rds_sock *rs, struct sockaddr_in *dest)
 	list_for_each_entry(rm, &list, m_sock_item) {
 
 		conn = rm->m_inc.i_conn;
+		if (conn->c_trans->t_mp_capable)
+			cp = rm->m_inc.i_conn_path;
+		else
+			cp = &conn->c_path[0];
 
-		spin_lock_irqsave(&conn->c_lock, flags);
+		spin_lock_irqsave(&cp->cp_lock, flags);
 		/*
 		 * Maybe someone else beat us to removing rm from the conn.
 		 * If we race with their flag update we'll get the lock and
 		 * then really see that the flag has been cleared.
 		 */
 		if (!test_and_clear_bit(RDS_MSG_ON_CONN, &rm->m_flags)) {
-			spin_unlock_irqrestore(&conn->c_lock, flags);
+			spin_unlock_irqrestore(&cp->cp_lock, flags);
 			spin_lock_irqsave(&rm->m_rs_lock, flags);
 			rm->m_rs = NULL;
 			spin_unlock_irqrestore(&rm->m_rs_lock, flags);
 			continue;
 		}
 		list_del_init(&rm->m_conn_item);
-		spin_unlock_irqrestore(&conn->c_lock, flags);
+		spin_unlock_irqrestore(&cp->cp_lock, flags);
 
 		/*
 		 * Couldn't grab m_rs_lock in top loop (lock ordering),
@@ -809,6 +793,7 @@ void rds_send_drop_to(struct rds_sock *rs, struct sockaddr_in *dest)
  * message from the flow with RDS_CANCEL_SENT_TO.
  */
 static int rds_send_queue_rm(struct rds_sock *rs, struct rds_connection *conn,
+			     struct rds_conn_path *cp,
 			     struct rds_message *rm, __be16 sport,
 			     __be16 dport, int *queued)
 {
@@ -852,13 +837,14 @@ static int rds_send_queue_rm(struct rds_sock *rs, struct rds_connection *conn,
 		   trying to minimize the time we hold c_lock */
 		rds_message_populate_header(&rm->m_inc.i_hdr, sport, dport, 0);
 		rm->m_inc.i_conn = conn;
+		rm->m_inc.i_conn_path = cp;
 		rds_message_addref(rm);
 
-		spin_lock(&conn->c_lock);
-		rm->m_inc.i_hdr.h_sequence = cpu_to_be64(conn->c_next_tx_seq++);
-		list_add_tail(&rm->m_conn_item, &conn->c_send_queue);
+		spin_lock(&cp->cp_lock);
+		rm->m_inc.i_hdr.h_sequence = cpu_to_be64(cp->cp_next_tx_seq++);
+		list_add_tail(&rm->m_conn_item, &cp->cp_send_queue);
 		set_bit(RDS_MSG_ON_CONN, &rm->m_flags);
-		spin_unlock(&conn->c_lock);
+		spin_unlock(&cp->cp_lock);
 
 		rdsdebug("queued msg %p len %d, rs %p bytes %d seq %llu\n",
 			 rm, len, rs, rs->rs_snd_bytes,
@@ -977,6 +963,29 @@ static int rds_cmsg_send(struct rds_sock *rs, struct rds_message *rm,
 	return ret;
 }
 
+static void rds_send_ping(struct rds_connection *conn);
+
+static int rds_send_mprds_hash(struct rds_sock *rs, struct rds_connection *conn)
+{
+	int hash;
+
+	if (conn->c_npaths == 0)
+		hash = RDS_MPATH_HASH(rs, RDS_MPATH_WORKERS);
+	else
+		hash = RDS_MPATH_HASH(rs, conn->c_npaths);
+	if (conn->c_npaths == 0 && hash != 0) {
+		rds_send_ping(conn);
+
+		if (conn->c_npaths == 0) {
+			wait_event_interruptible(conn->c_hs_waitq,
+						 (conn->c_npaths != 0));
+		}
+		if (conn->c_npaths == 1)
+			hash = 0;
+	}
+	return hash;
+}
+
 int rds_sendmsg(struct socket *sock, struct msghdr *msg, size_t payload_len)
 {
 	struct sock *sk = sock->sk;
@@ -990,6 +999,7 @@ int rds_sendmsg(struct socket *sock, struct msghdr *msg, size_t payload_len)
 	int queued = 0, allocated_mr = 0;
 	int nonblock = msg->msg_flags & MSG_DONTWAIT;
 	long timeo = sock_sndtimeo(sk, nonblock);
+	struct rds_conn_path *cpath;
 
 	/* Mirror Linux UDP mirror of BSD error message compatibility */
 	/* XXX: Perhaps MSG_MORE someday */
@@ -1088,15 +1098,19 @@ int rds_sendmsg(struct socket *sock, struct msghdr *msg, size_t payload_len)
 		goto out;
 	}
 
-	rds_conn_connect_if_down(conn);
+	if (conn->c_trans->t_mp_capable)
+		cpath = &conn->c_path[rds_send_mprds_hash(rs, conn)];
+	else
+		cpath = &conn->c_path[0];
+
+	rds_conn_path_connect_if_down(cpath);
 
 	ret = rds_cong_wait(conn->c_fcong, dport, nonblock, rs);
 	if (ret) {
 		rs->rs_seen_congestion = 1;
 		goto out;
 	}
-
-	while (!rds_send_queue_rm(rs, conn, rm, rs->rs_bound_port,
+	while (!rds_send_queue_rm(rs, conn, cpath, rm, rs->rs_bound_port,
 				  dport, &queued)) {
 		rds_stats_inc(s_send_queue_full);
 
@@ -1106,7 +1120,7 @@ int rds_sendmsg(struct socket *sock, struct msghdr *msg, size_t payload_len)
 		}
 
 		timeo = wait_event_interruptible_timeout(*sk_sleep(sk),
-					rds_send_queue_rm(rs, conn, rm,
+					rds_send_queue_rm(rs, conn, cpath, rm,
 							  rs->rs_bound_port,
 							  dport,
 							  &queued),
@@ -1127,9 +1141,9 @@ int rds_sendmsg(struct socket *sock, struct msghdr *msg, size_t payload_len)
 	 */
 	rds_stats_inc(s_send_queued);
 
-	ret = rds_send_xmit(conn);
+	ret = rds_send_xmit(cpath);
 	if (ret == -ENOMEM || ret == -EAGAIN)
-		queue_delayed_work(rds_wq, &conn->c_send_w, 1);
+		queue_delayed_work(rds_wq, &cpath->cp_send_w, 1);
 
 	rds_message_put(rm);
 	return payload_len;
@@ -1147,10 +1161,16 @@ out:
 }
 
 /*
- * Reply to a ping packet.
+ * send out a probe. Can be shared by rds_send_ping,
+ * rds_send_pong, rds_send_hb.
+ * rds_send_hb should use h_flags
+ *   RDS_FLAG_HB_PING|RDS_FLAG_ACK_REQUIRED
+ * or
+ *   RDS_FLAG_HB_PONG|RDS_FLAG_ACK_REQUIRED
  */
 int
-rds_send_pong(struct rds_connection *conn, __be16 dport)
+rds_send_probe(struct rds_conn_path *cp, __be16 sport,
+	       __be16 dport, u8 h_flags)
 {
 	struct rds_message *rm;
 	unsigned long flags;
@@ -1162,31 +1182,41 @@ rds_send_pong(struct rds_connection *conn, __be16 dport)
 		goto out;
 	}
 
-	rm->m_daddr = conn->c_faddr;
+	rm->m_daddr = cp->cp_conn->c_faddr;
 	rm->data.op_active = 1;
 
-	rds_conn_connect_if_down(conn);
+	rds_conn_path_connect_if_down(cp);
 
-	ret = rds_cong_wait(conn->c_fcong, dport, 1, NULL);
+	ret = rds_cong_wait(cp->cp_conn->c_fcong, dport, 1, NULL);
 	if (ret)
 		goto out;
 
-	spin_lock_irqsave(&conn->c_lock, flags);
-	list_add_tail(&rm->m_conn_item, &conn->c_send_queue);
+	spin_lock_irqsave(&cp->cp_lock, flags);
+	list_add_tail(&rm->m_conn_item, &cp->cp_send_queue);
 	set_bit(RDS_MSG_ON_CONN, &rm->m_flags);
 	rds_message_addref(rm);
-	rm->m_inc.i_conn = conn;
+	rm->m_inc.i_conn = cp->cp_conn;
+	rm->m_inc.i_conn_path = cp;
+
+	rds_message_populate_header(&rm->m_inc.i_hdr, sport, dport,
+				    cp->cp_next_tx_seq);
+	rm->m_inc.i_hdr.h_flags |= h_flags;
+	cp->cp_next_tx_seq++;
+
+	if (RDS_HS_PROBE(sport, dport) && cp->cp_conn->c_trans->t_mp_capable) {
+		u16 npaths = RDS_MPATH_WORKERS;
 
-	rds_message_populate_header(&rm->m_inc.i_hdr, 0, dport,
-				    conn->c_next_tx_seq);
-	conn->c_next_tx_seq++;
-	spin_unlock_irqrestore(&conn->c_lock, flags);
+		rds_message_add_extension(&rm->m_inc.i_hdr,
+					  RDS_EXTHDR_NPATHS, &npaths,
+					  sizeof(npaths));
+	}
+	spin_unlock_irqrestore(&cp->cp_lock, flags);
 
 	rds_stats_inc(s_send_queued);
 	rds_stats_inc(s_send_pong);
 
 	/* schedule the send work on rds_wq */
-	queue_delayed_work(rds_wq, &conn->c_send_w, 1);
+	queue_delayed_work(rds_wq, &cp->cp_send_w, 1);
 
 	rds_message_put(rm);
 	return 0;
@@ -1196,3 +1226,25 @@ out:
 		rds_message_put(rm);
 	return ret;
 }
+
+int
+rds_send_pong(struct rds_conn_path *cp, __be16 dport)
+{
+	return rds_send_probe(cp, 0, dport, 0);
+}
+
+void
+rds_send_ping(struct rds_connection *conn)
+{
+	unsigned long flags;
+	struct rds_conn_path *cp = &conn->c_path[0];
+
+	spin_lock_irqsave(&cp->cp_lock, flags);
+	if (conn->c_ping_triggered) {
+		spin_unlock_irqrestore(&cp->cp_lock, flags);
+		return;
+	}
+	conn->c_ping_triggered = 1;
+	spin_unlock_irqrestore(&cp->cp_lock, flags);
+	rds_send_probe(&conn->c_path[0], RDS_FLAG_PROBE_PORT, 0, 0);
+}
diff --git a/net/rds/tcp.c b/net/rds/tcp.c
index c8a7b4c90190..fcddacc92e01 100644
--- a/net/rds/tcp.c
+++ b/net/rds/tcp.c
@@ -56,8 +56,8 @@ static int rds_tcp_skbuf_handler(struct ctl_table *ctl, int write,
 				 void __user *buffer, size_t *lenp,
 				 loff_t *fpos);
 
-int rds_tcp_min_sndbuf = SOCK_MIN_SNDBUF;
-int rds_tcp_min_rcvbuf = SOCK_MIN_RCVBUF;
+static int rds_tcp_min_sndbuf = SOCK_MIN_SNDBUF;
+static int rds_tcp_min_rcvbuf = SOCK_MIN_RCVBUF;
 
 static struct ctl_table rds_tcp_sysctl_table[] = {
 #define	RDS_TCP_SNDBUF	0
@@ -135,9 +135,9 @@ void rds_tcp_restore_callbacks(struct socket *sock,
  * from being called while it isn't set.
  */
 void rds_tcp_reset_callbacks(struct socket *sock,
-			     struct rds_connection *conn)
+			     struct rds_conn_path *cp)
 {
-	struct rds_tcp_connection *tc = conn->c_transport_data;
+	struct rds_tcp_connection *tc = cp->cp_transport_data;
 	struct socket *osock = tc->t_sock;
 
 	if (!osock)
@@ -147,8 +147,8 @@ void rds_tcp_reset_callbacks(struct socket *sock,
 	 * 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. We quiesce these threads by setting
-	 * c_state to something other than RDS_CONN_UP, and then
+	 * cp_transport_data. We quiesce these threads by setting
+	 * cp_state to something other than RDS_CONN_UP, and then
 	 * waiting for any existing threads in rds_send_xmit to
 	 * complete release_in_xmit(). (Subsequent threads entering
 	 * rds_send_xmit() will bail on !rds_conn_up().
@@ -163,38 +163,25 @@ void rds_tcp_reset_callbacks(struct socket *sock,
 	 * RDS_CONN_RESETTTING, to ensure that rds_tcp_state_change
 	 * cannot mark rds_conn_path_up() in the window before lock_sock()
 	 */
-	atomic_set(&conn->c_state, RDS_CONN_RESETTING);
-	wait_event(conn->c_waitq, !test_bit(RDS_IN_XMIT, &conn->c_flags));
+	atomic_set(&cp->cp_state, RDS_CONN_RESETTING);
+	wait_event(cp->cp_waitq, !test_bit(RDS_IN_XMIT, &cp->cp_flags));
 	lock_sock(osock->sk);
 	/* reset receive side state for rds_tcp_data_recv() for osock  */
+	cancel_delayed_work_sync(&cp->cp_send_w);
+	cancel_delayed_work_sync(&cp->cp_recv_w);
 	if (tc->t_tinc) {
 		rds_inc_put(&tc->t_tinc->ti_inc);
 		tc->t_tinc = NULL;
 	}
 	tc->t_tinc_hdr_rem = sizeof(struct rds_header);
 	tc->t_tinc_data_rem = 0;
-	tc->t_sock = NULL;
-
-	write_lock_bh(&osock->sk->sk_callback_lock);
-
-	osock->sk->sk_user_data = NULL;
-	osock->sk->sk_data_ready = tc->t_orig_data_ready;
-	osock->sk->sk_write_space = tc->t_orig_write_space;
-	osock->sk->sk_state_change = tc->t_orig_state_change;
-	write_unlock_bh(&osock->sk->sk_callback_lock);
+	rds_tcp_restore_callbacks(osock, tc);
 	release_sock(osock->sk);
 	sock_release(osock);
 newsock:
-	rds_send_reset(conn);
+	rds_send_path_reset(cp);
 	lock_sock(sock->sk);
-	write_lock_bh(&sock->sk->sk_callback_lock);
-	tc->t_sock = sock;
-	sock->sk->sk_user_data = conn;
-	sock->sk->sk_data_ready = rds_tcp_data_ready;
-	sock->sk->sk_write_space = rds_tcp_write_space;
-	sock->sk->sk_state_change = rds_tcp_state_change;
-
-	write_unlock_bh(&sock->sk->sk_callback_lock);
+	rds_tcp_set_callbacks(sock, cp);
 	release_sock(sock->sk);
 }
 
@@ -202,9 +189,9 @@ newsock:
  * above rds_tcp_reset_callbacks for notes about synchronization
  * with data path
  */
-void rds_tcp_set_callbacks(struct socket *sock, struct rds_connection *conn)
+void rds_tcp_set_callbacks(struct socket *sock, struct rds_conn_path *cp)
 {
-	struct rds_tcp_connection *tc = conn->c_transport_data;
+	struct rds_tcp_connection *tc = cp->cp_transport_data;
 
 	rdsdebug("setting sock %p callbacks to tc %p\n", sock, tc);
 	write_lock_bh(&sock->sk->sk_callback_lock);
@@ -220,12 +207,12 @@ void rds_tcp_set_callbacks(struct socket *sock, struct rds_connection *conn)
 		sock->sk->sk_data_ready = sock->sk->sk_user_data;
 
 	tc->t_sock = sock;
-	tc->conn = conn;
+	tc->t_cpath = cp;
 	tc->t_orig_data_ready = sock->sk->sk_data_ready;
 	tc->t_orig_write_space = sock->sk->sk_write_space;
 	tc->t_orig_state_change = sock->sk->sk_state_change;
 
-	sock->sk->sk_user_data = conn;
+	sock->sk->sk_user_data = cp;
 	sock->sk->sk_data_ready = rds_tcp_data_ready;
 	sock->sk->sk_write_space = rds_tcp_write_space;
 	sock->sk->sk_state_change = rds_tcp_state_change;
@@ -283,24 +270,29 @@ static int rds_tcp_laddr_check(struct net *net, __be32 addr)
 static int rds_tcp_conn_alloc(struct rds_connection *conn, gfp_t gfp)
 {
 	struct rds_tcp_connection *tc;
+	int i;
 
-	tc = kmem_cache_alloc(rds_tcp_conn_slab, gfp);
-	if (!tc)
-		return -ENOMEM;
+	for (i = 0; i < RDS_MPATH_WORKERS; i++) {
+		tc = kmem_cache_alloc(rds_tcp_conn_slab, 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);
-	tc->t_tinc_data_rem = 0;
+		mutex_init(&tc->t_conn_path_lock);
+		tc->t_sock = NULL;
+		tc->t_tinc = NULL;
+		tc->t_tinc_hdr_rem = sizeof(struct rds_header);
+		tc->t_tinc_data_rem = 0;
 
-	conn->c_transport_data = tc;
+		conn->c_path[i].cp_transport_data = tc;
+		tc->t_cpath = &conn->c_path[i];
 
-	spin_lock_irq(&rds_tcp_conn_lock);
-	list_add_tail(&tc->t_tcp_node, &rds_tcp_conn_list);
-	spin_unlock_irq(&rds_tcp_conn_lock);
+		spin_lock_irq(&rds_tcp_conn_lock);
+		list_add_tail(&tc->t_tcp_node, &rds_tcp_conn_list);
+		spin_unlock_irq(&rds_tcp_conn_lock);
+		rdsdebug("rds_conn_path [%d] tc %p\n", i,
+			 conn->c_path[i].cp_transport_data);
+	}
 
-	rdsdebug("alloced tc %p\n", conn->c_transport_data);
 	return 0;
 }
 
@@ -317,6 +309,17 @@ static void rds_tcp_conn_free(void *arg)
 	kmem_cache_free(rds_tcp_conn_slab, tc);
 }
 
+static bool list_has_conn(struct list_head *list, struct rds_connection *conn)
+{
+	struct rds_tcp_connection *tc, *_tc;
+
+	list_for_each_entry_safe(tc, _tc, list, t_tcp_node) {
+		if (tc->t_cpath->cp_conn == conn)
+			return true;
+	}
+	return false;
+}
+
 static void rds_tcp_destroy_conns(void)
 {
 	struct rds_tcp_connection *tc, *_tc;
@@ -324,29 +327,28 @@ static void rds_tcp_destroy_conns(void)
 
 	/* avoid calling conn_destroy with irqs off */
 	spin_lock_irq(&rds_tcp_conn_lock);
-	list_splice(&rds_tcp_conn_list, &tmp_list);
-	INIT_LIST_HEAD(&rds_tcp_conn_list);
+	list_for_each_entry_safe(tc, _tc, &rds_tcp_conn_list, t_tcp_node) {
+		if (!list_has_conn(&tmp_list, tc->t_cpath->cp_conn))
+			list_move_tail(&tc->t_tcp_node, &tmp_list);
+	}
 	spin_unlock_irq(&rds_tcp_conn_lock);
 
-	list_for_each_entry_safe(tc, _tc, &tmp_list, t_tcp_node) {
-		if (tc->conn->c_passive)
-			rds_conn_destroy(tc->conn->c_passive);
-		rds_conn_destroy(tc->conn);
-	}
+	list_for_each_entry_safe(tc, _tc, &tmp_list, t_tcp_node)
+		rds_conn_destroy(tc->t_cpath->cp_conn);
 }
 
 static void rds_tcp_exit(void);
 
 struct rds_transport rds_tcp_transport = {
 	.laddr_check		= rds_tcp_laddr_check,
-	.xmit_prepare		= rds_tcp_xmit_prepare,
-	.xmit_complete		= rds_tcp_xmit_complete,
+	.xmit_path_prepare	= rds_tcp_xmit_path_prepare,
+	.xmit_path_complete	= rds_tcp_xmit_path_complete,
 	.xmit			= rds_tcp_xmit,
-	.recv			= rds_tcp_recv,
+	.recv_path		= rds_tcp_recv_path,
 	.conn_alloc		= rds_tcp_conn_alloc,
 	.conn_free		= rds_tcp_conn_free,
-	.conn_connect		= rds_tcp_conn_connect,
-	.conn_shutdown		= rds_tcp_conn_shutdown,
+	.conn_path_connect	= rds_tcp_conn_path_connect,
+	.conn_path_shutdown	= rds_tcp_conn_path_shutdown,
 	.inc_copy_to_user	= rds_tcp_inc_copy_to_user,
 	.inc_free		= rds_tcp_inc_free,
 	.stats_info_copy	= rds_tcp_stats_info_copy,
@@ -355,6 +357,7 @@ struct rds_transport rds_tcp_transport = {
 	.t_name			= "tcp",
 	.t_type			= RDS_TRANS_TCP,
 	.t_prefer_loopback	= 1,
+	.t_mp_capable		= 1,
 };
 
 static int rds_tcp_netid;
@@ -488,10 +491,30 @@ static struct pernet_operations rds_tcp_net_ops = {
 	.size = sizeof(struct rds_tcp_net),
 };
 
+/* explicitly send a RST on each socket, thereby releasing any socket refcnts
+ * that may otherwise hold up netns deletion.
+ */
+static void rds_tcp_conn_paths_destroy(struct rds_connection *conn)
+{
+	struct rds_conn_path *cp;
+	struct rds_tcp_connection *tc;
+	int i;
+	struct sock *sk;
+
+	for (i = 0; i < RDS_MPATH_WORKERS; i++) {
+		cp = &conn->c_path[i];
+		tc = cp->cp_transport_data;
+		if (!tc->t_sock)
+			continue;
+		sk = tc->t_sock->sk;
+		sk->sk_prot->disconnect(sk, 0);
+		tcp_done(sk);
+	}
+}
+
 static void rds_tcp_kill_sock(struct net *net)
 {
 	struct rds_tcp_connection *tc, *_tc;
-	struct sock *sk;
 	LIST_HEAD(tmp_list);
 	struct rds_tcp_net *rtn = net_generic(net, rds_tcp_netid);
 
@@ -500,23 +523,27 @@ static void rds_tcp_kill_sock(struct net *net)
 	flush_work(&rtn->rds_tcp_accept_w);
 	spin_lock_irq(&rds_tcp_conn_lock);
 	list_for_each_entry_safe(tc, _tc, &rds_tcp_conn_list, t_tcp_node) {
-		struct net *c_net = read_pnet(&tc->conn->c_net);
+		struct net *c_net = read_pnet(&tc->t_cpath->cp_conn->c_net);
 
 		if (net != c_net || !tc->t_sock)
 			continue;
-		list_move_tail(&tc->t_tcp_node, &tmp_list);
+		if (!list_has_conn(&tmp_list, tc->t_cpath->cp_conn))
+			list_move_tail(&tc->t_tcp_node, &tmp_list);
 	}
 	spin_unlock_irq(&rds_tcp_conn_lock);
 	list_for_each_entry_safe(tc, _tc, &tmp_list, t_tcp_node) {
-		sk = tc->t_sock->sk;
-		sk->sk_prot->disconnect(sk, 0);
-		tcp_done(sk);
-		if (tc->conn->c_passive)
-			rds_conn_destroy(tc->conn->c_passive);
-		rds_conn_destroy(tc->conn);
+		rds_tcp_conn_paths_destroy(tc->t_cpath->cp_conn);
+		rds_conn_destroy(tc->t_cpath->cp_conn);
 	}
 }
 
+void *rds_tcp_listen_sock_def_readable(struct net *net)
+{
+	struct rds_tcp_net *rtn = net_generic(net, rds_tcp_netid);
+
+	return rtn->rds_tcp_listen_sock->sk->sk_user_data;
+}
+
 static int rds_tcp_dev_event(struct notifier_block *this,
 			     unsigned long event, void *ptr)
 {
@@ -551,12 +578,13 @@ static void rds_tcp_sysctl_reset(struct net *net)
 
 	spin_lock_irq(&rds_tcp_conn_lock);
 	list_for_each_entry_safe(tc, _tc, &rds_tcp_conn_list, t_tcp_node) {
-		struct net *c_net = read_pnet(&tc->conn->c_net);
+		struct net *c_net = read_pnet(&tc->t_cpath->cp_conn->c_net);
 
 		if (net != c_net || !tc->t_sock)
 			continue;
 
-		rds_conn_drop(tc->conn); /* reconnect with new parameters */
+		/* reconnect with new parameters */
+		rds_conn_path_drop(tc->t_cpath);
 	}
 	spin_unlock_irq(&rds_tcp_conn_lock);
 }
diff --git a/net/rds/tcp.h b/net/rds/tcp.h
index 7940babf6c71..9a1cc8906576 100644
--- a/net/rds/tcp.h
+++ b/net/rds/tcp.h
@@ -11,11 +11,11 @@ struct rds_tcp_incoming {
 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 rds_conn_path	*t_cpath;
+	/* t_conn_path_lock synchronizes the connection establishment between
+	 * rds_tcp_accept_one and rds_tcp_conn_path_connect
 	 */
-	struct mutex		t_conn_lock;
+	struct mutex		t_conn_path_lock;
 	struct socket		*t_sock;
 	void			*t_orig_write_space;
 	void			*t_orig_data_ready;
@@ -49,8 +49,8 @@ struct rds_tcp_statistics {
 /* tcp.c */
 void rds_tcp_tune(struct socket *sock);
 void rds_tcp_nonagle(struct socket *sock);
-void rds_tcp_set_callbacks(struct socket *sock, struct rds_connection *conn);
-void rds_tcp_reset_callbacks(struct socket *sock, struct rds_connection *conn);
+void rds_tcp_set_callbacks(struct socket *sock, struct rds_conn_path *cp);
+void rds_tcp_reset_callbacks(struct socket *sock, struct rds_conn_path *cp);
 void rds_tcp_restore_callbacks(struct socket *sock,
 			       struct rds_tcp_connection *tc);
 u32 rds_tcp_snd_nxt(struct rds_tcp_connection *tc);
@@ -60,8 +60,8 @@ extern struct rds_transport rds_tcp_transport;
 void rds_tcp_accept_work(struct sock *sk);
 
 /* tcp_connect.c */
-int rds_tcp_conn_connect(struct rds_connection *conn);
-void rds_tcp_conn_shutdown(struct rds_connection *conn);
+int rds_tcp_conn_path_connect(struct rds_conn_path *cp);
+void rds_tcp_conn_path_shutdown(struct rds_conn_path *conn);
 void rds_tcp_state_change(struct sock *sk);
 
 /* tcp_listen.c */
@@ -70,18 +70,19 @@ void rds_tcp_listen_stop(struct socket *);
 void rds_tcp_listen_data_ready(struct sock *sk);
 int rds_tcp_accept_one(struct socket *sock);
 int rds_tcp_keepalive(struct socket *sock);
+void *rds_tcp_listen_sock_def_readable(struct net *net);
 
 /* tcp_recv.c */
 int rds_tcp_recv_init(void);
 void rds_tcp_recv_exit(void);
 void rds_tcp_data_ready(struct sock *sk);
-int rds_tcp_recv(struct rds_connection *conn);
+int rds_tcp_recv_path(struct rds_conn_path *cp);
 void rds_tcp_inc_free(struct rds_incoming *inc);
 int rds_tcp_inc_copy_to_user(struct rds_incoming *inc, struct iov_iter *to);
 
 /* tcp_send.c */
-void rds_tcp_xmit_prepare(struct rds_connection *conn);
-void rds_tcp_xmit_complete(struct rds_connection *conn);
+void rds_tcp_xmit_path_prepare(struct rds_conn_path *cp);
+void rds_tcp_xmit_path_complete(struct rds_conn_path *cp);
 int rds_tcp_xmit(struct rds_connection *conn, struct rds_message *rm,
 		 unsigned int hdr_off, unsigned int sg, unsigned int off);
 void rds_tcp_write_space(struct sock *sk);
diff --git a/net/rds/tcp_connect.c b/net/rds/tcp_connect.c
index f6e95d60db54..05f61c533ed3 100644
--- a/net/rds/tcp_connect.c
+++ b/net/rds/tcp_connect.c
@@ -40,16 +40,16 @@
 void rds_tcp_state_change(struct sock *sk)
 {
 	void (*state_change)(struct sock *sk);
-	struct rds_connection *conn;
+	struct rds_conn_path *cp;
 	struct rds_tcp_connection *tc;
 
 	read_lock_bh(&sk->sk_callback_lock);
-	conn = sk->sk_user_data;
-	if (!conn) {
+	cp = sk->sk_user_data;
+	if (!cp) {
 		state_change = sk->sk_state_change;
 		goto out;
 	}
-	tc = conn->c_transport_data;
+	tc = cp->cp_transport_data;
 	state_change = tc->t_orig_state_change;
 
 	rdsdebug("sock %p state_change to %d\n", tc->t_sock, sk->sk_state);
@@ -60,11 +60,11 @@ void rds_tcp_state_change(struct sock *sk)
 	case TCP_SYN_RECV:
 		break;
 	case TCP_ESTABLISHED:
-		rds_connect_path_complete(conn, RDS_CONN_CONNECTING);
+		rds_connect_path_complete(cp, RDS_CONN_CONNECTING);
 		break;
 	case TCP_CLOSE_WAIT:
 	case TCP_CLOSE:
-		rds_conn_drop(conn);
+		rds_conn_path_drop(cp);
 	default:
 		break;
 	}
@@ -73,17 +73,24 @@ out:
 	state_change(sk);
 }
 
-int rds_tcp_conn_connect(struct rds_connection *conn)
+int rds_tcp_conn_path_connect(struct rds_conn_path *cp)
 {
 	struct socket *sock = NULL;
 	struct sockaddr_in src, dest;
 	int ret;
-	struct rds_tcp_connection *tc = conn->c_transport_data;
+	struct rds_connection *conn = cp->cp_conn;
+	struct rds_tcp_connection *tc = cp->cp_transport_data;
 
-	mutex_lock(&tc->t_conn_lock);
+	/* for multipath rds,we only trigger the connection after
+	 * the handshake probe has determined the number of paths.
+	 */
+	if (cp->cp_index > 0 && cp->cp_conn->c_npaths < 2)
+		return -EAGAIN;
+
+	mutex_lock(&tc->t_conn_path_lock);
 
-	if (rds_conn_up(conn)) {
-		mutex_unlock(&tc->t_conn_lock);
+	if (rds_conn_path_up(cp)) {
+		mutex_unlock(&tc->t_conn_path_lock);
 		return 0;
 	}
 	ret = sock_create_kern(rds_conn_net(conn), PF_INET,
@@ -112,10 +119,11 @@ int rds_tcp_conn_connect(struct rds_connection *conn)
 	 * once we call connect() we can start getting callbacks and they
 	 * own the socket
 	 */
-	rds_tcp_set_callbacks(sock, conn);
+	rds_tcp_set_callbacks(sock, cp);
 	ret = sock->ops->connect(sock, (struct sockaddr *)&dest, sizeof(dest),
 				 O_NONBLOCK);
 
+	cp->cp_outgoing = 1;
 	rdsdebug("connect to address %pI4 returned %d\n", &conn->c_faddr, ret);
 	if (ret == -EINPROGRESS)
 		ret = 0;
@@ -123,11 +131,11 @@ int rds_tcp_conn_connect(struct rds_connection *conn)
 		rds_tcp_keepalive(sock);
 		sock = NULL;
 	} else {
-		rds_tcp_restore_callbacks(sock, conn->c_transport_data);
+		rds_tcp_restore_callbacks(sock, cp->cp_transport_data);
 	}
 
 out:
-	mutex_unlock(&tc->t_conn_lock);
+	mutex_unlock(&tc->t_conn_path_lock);
 	if (sock)
 		sock_release(sock);
 	return ret;
@@ -142,12 +150,13 @@ out:
  * callbacks to those set by TCP.  Our callbacks won't execute again once we
  * hold the sock lock.
  */
-void rds_tcp_conn_shutdown(struct rds_connection *conn)
+void rds_tcp_conn_path_shutdown(struct rds_conn_path *cp)
 {
-	struct rds_tcp_connection *tc = conn->c_transport_data;
+	struct rds_tcp_connection *tc = cp->cp_transport_data;
 	struct socket *sock = tc->t_sock;
 
-	rdsdebug("shutting down conn %p tc %p sock %p\n", conn, tc, sock);
+	rdsdebug("shutting down conn %p tc %p sock %p\n",
+		 cp->cp_conn, tc, sock);
 
 	if (sock) {
 		sock->ops->shutdown(sock, RCV_SHUTDOWN | SEND_SHUTDOWN);
diff --git a/net/rds/tcp_listen.c b/net/rds/tcp_listen.c
index 245542ca4718..e0b23fb5b8d5 100644
--- a/net/rds/tcp_listen.c
+++ b/net/rds/tcp_listen.c
@@ -70,6 +70,52 @@ bail:
 	return ret;
 }
 
+/* rds_tcp_accept_one_path(): if accepting on cp_index > 0, make sure the
+ * client's ipaddr < server's ipaddr. Otherwise, close the accepted
+ * socket and force a reconneect from smaller -> larger ip addr. The reason
+ * we special case cp_index 0 is to allow the rds probe ping itself to itself
+ * get through efficiently.
+ * Since reconnects are only initiated from the node with the numerically
+ * smaller ip address, we recycle conns in RDS_CONN_ERROR on the passive side
+ * by moving them to CONNECTING in this function.
+ */
+struct rds_tcp_connection *rds_tcp_accept_one_path(struct rds_connection *conn)
+{
+	int i;
+	bool peer_is_smaller = (conn->c_faddr < conn->c_laddr);
+	int npaths = conn->c_npaths;
+
+	if (npaths <= 1) {
+		struct rds_conn_path *cp = &conn->c_path[0];
+		int ret;
+
+		ret = rds_conn_path_transition(cp, RDS_CONN_DOWN,
+					       RDS_CONN_CONNECTING);
+		if (!ret)
+			rds_conn_path_transition(cp, RDS_CONN_ERROR,
+						 RDS_CONN_CONNECTING);
+		return cp->cp_transport_data;
+	}
+
+	/* for mprds, paths with cp_index > 0 MUST be initiated by the peer
+	 * with the smaller address.
+	 */
+	if (!peer_is_smaller)
+		return NULL;
+
+	for (i = 1; i < npaths; i++) {
+		struct rds_conn_path *cp = &conn->c_path[i];
+
+		if (rds_conn_path_transition(cp, RDS_CONN_DOWN,
+					     RDS_CONN_CONNECTING) ||
+		    rds_conn_path_transition(cp, RDS_CONN_ERROR,
+					     RDS_CONN_CONNECTING)) {
+			return cp->cp_transport_data;
+		}
+	}
+	return NULL;
+}
+
 int rds_tcp_accept_one(struct socket *sock)
 {
 	struct socket *new_sock = NULL;
@@ -78,6 +124,7 @@ int rds_tcp_accept_one(struct socket *sock)
 	struct inet_sock *inet;
 	struct rds_tcp_connection *rs_tcp = NULL;
 	int conn_state;
+	struct rds_conn_path *cp;
 
 	if (!sock) /* module unload or netns delete in progress */
 		return -ENETUNREACH;
@@ -118,11 +165,14 @@ int rds_tcp_accept_one(struct socket *sock)
 	 * If the client reboots, this conn will need to be cleaned up.
 	 * rds_tcp_state_change() will do that cleanup
 	 */
-	rs_tcp = (struct rds_tcp_connection *)conn->c_transport_data;
-	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)
+	rs_tcp = rds_tcp_accept_one_path(conn);
+	if (!rs_tcp)
+		goto rst_nsk;
+	mutex_lock(&rs_tcp->t_conn_path_lock);
+	cp = rs_tcp->t_cpath;
+	conn_state = rds_conn_path_state(cp);
+	if (conn_state != RDS_CONN_CONNECTING && conn_state != RDS_CONN_UP &&
+	    conn_state != RDS_CONN_ERROR)
 		goto rst_nsk;
 	if (rs_tcp->t_sock) {
 		/* Need to resolve a duelling SYN between peers.
@@ -132,17 +182,17 @@ int rds_tcp_accept_one(struct socket *sock)
 		 * c_transport_data.
 		 */
 		if (ntohl(inet->inet_saddr) < ntohl(inet->inet_daddr) ||
-		    !conn->c_outgoing) {
+		    !cp->cp_outgoing) {
 			goto rst_nsk;
 		} else {
-			rds_tcp_reset_callbacks(new_sock, conn);
-			conn->c_outgoing = 0;
+			rds_tcp_reset_callbacks(new_sock, cp);
+			cp->cp_outgoing = 0;
 			/* rds_connect_path_complete() marks RDS_CONN_UP */
-			rds_connect_path_complete(conn, RDS_CONN_RESETTING);
+			rds_connect_path_complete(cp, RDS_CONN_RESETTING);
 		}
 	} else {
-		rds_tcp_set_callbacks(new_sock, conn);
-		rds_connect_path_complete(conn, RDS_CONN_CONNECTING);
+		rds_tcp_set_callbacks(new_sock, cp);
+		rds_connect_path_complete(cp, RDS_CONN_CONNECTING);
 	}
 	new_sock = NULL;
 	ret = 0;
@@ -153,7 +203,7 @@ rst_nsk:
 	ret = 0;
 out:
 	if (rs_tcp)
-		mutex_unlock(&rs_tcp->t_conn_lock);
+		mutex_unlock(&rs_tcp->t_conn_path_lock);
 	if (new_sock)
 		sock_release(new_sock);
 	return ret;
@@ -180,6 +230,8 @@ void rds_tcp_listen_data_ready(struct sock *sk)
 	 */
 	if (sk->sk_state == TCP_LISTEN)
 		rds_tcp_accept_work(sk);
+	else
+		ready = rds_tcp_listen_sock_def_readable(sock_net(sk));
 
 out:
 	read_unlock_bh(&sk->sk_callback_lock);
diff --git a/net/rds/tcp_recv.c b/net/rds/tcp_recv.c
index 6e6a7111a034..ad4892e97f91 100644
--- a/net/rds/tcp_recv.c
+++ b/net/rds/tcp_recv.c
@@ -147,7 +147,7 @@ static void rds_tcp_cong_recv(struct rds_connection *conn,
 }
 
 struct rds_tcp_desc_arg {
-	struct rds_connection *conn;
+	struct rds_conn_path *conn_path;
 	gfp_t gfp;
 };
 
@@ -155,8 +155,8 @@ static int rds_tcp_data_recv(read_descriptor_t *desc, struct sk_buff *skb,
 			     unsigned int offset, size_t len)
 {
 	struct rds_tcp_desc_arg *arg = desc->arg.data;
-	struct rds_connection *conn = arg->conn;
-	struct rds_tcp_connection *tc = conn->c_transport_data;
+	struct rds_conn_path *cp = arg->conn_path;
+	struct rds_tcp_connection *tc = cp->cp_transport_data;
 	struct rds_tcp_incoming *tinc = tc->t_tinc;
 	struct sk_buff *clone;
 	size_t left = len, to_copy;
@@ -178,7 +178,8 @@ static int rds_tcp_data_recv(read_descriptor_t *desc, struct sk_buff *skb,
 			}
 			tc->t_tinc = tinc;
 			rdsdebug("alloced tinc %p\n", tinc);
-			rds_inc_init(&tinc->ti_inc, conn, conn->c_faddr);
+			rds_inc_path_init(&tinc->ti_inc, cp,
+					  cp->cp_conn->c_faddr);
 			/*
 			 * XXX * we might be able to use the __ variants when
 			 * we've already serialized at a higher level.
@@ -228,6 +229,8 @@ static int rds_tcp_data_recv(read_descriptor_t *desc, struct sk_buff *skb,
 		}
 
 		if (tc->t_tinc_hdr_rem == 0 && tc->t_tinc_data_rem == 0) {
+			struct rds_connection *conn = cp->cp_conn;
+
 			if (tinc->ti_inc.i_hdr.h_flags == RDS_FLAG_CONG_BITMAP)
 				rds_tcp_cong_recv(conn, tinc);
 			else
@@ -250,15 +253,15 @@ out:
 }
 
 /* the caller has to hold the sock lock */
-static int rds_tcp_read_sock(struct rds_connection *conn, gfp_t gfp)
+static int rds_tcp_read_sock(struct rds_conn_path *cp, gfp_t gfp)
 {
-	struct rds_tcp_connection *tc = conn->c_transport_data;
+	struct rds_tcp_connection *tc = cp->cp_transport_data;
 	struct socket *sock = tc->t_sock;
 	read_descriptor_t desc;
 	struct rds_tcp_desc_arg arg;
 
 	/* It's like glib in the kernel! */
-	arg.conn = conn;
+	arg.conn_path = cp;
 	arg.gfp = gfp;
 	desc.arg.data = &arg;
 	desc.error = 0;
@@ -278,16 +281,17 @@ static int rds_tcp_read_sock(struct rds_connection *conn, gfp_t gfp)
  * if we fail to allocate we're in trouble.. blindly wait some time before
  * trying again to see if the VM can free up something for us.
  */
-int rds_tcp_recv(struct rds_connection *conn)
+int rds_tcp_recv_path(struct rds_conn_path *cp)
 {
-	struct rds_tcp_connection *tc = conn->c_transport_data;
+	struct rds_tcp_connection *tc = cp->cp_transport_data;
 	struct socket *sock = tc->t_sock;
 	int ret = 0;
 
-	rdsdebug("recv worker conn %p tc %p sock %p\n", conn, tc, sock);
+	rdsdebug("recv worker path [%d] tc %p sock %p\n",
+		 cp->cp_index, tc, sock);
 
 	lock_sock(sock->sk);
-	ret = rds_tcp_read_sock(conn, GFP_KERNEL);
+	ret = rds_tcp_read_sock(cp, GFP_KERNEL);
 	release_sock(sock->sk);
 
 	return ret;
@@ -296,24 +300,24 @@ int rds_tcp_recv(struct rds_connection *conn)
 void rds_tcp_data_ready(struct sock *sk)
 {
 	void (*ready)(struct sock *sk);
-	struct rds_connection *conn;
+	struct rds_conn_path *cp;
 	struct rds_tcp_connection *tc;
 
 	rdsdebug("data ready sk %p\n", sk);
 
 	read_lock_bh(&sk->sk_callback_lock);
-	conn = sk->sk_user_data;
-	if (!conn) { /* check for teardown race */
+	cp = sk->sk_user_data;
+	if (!cp) { /* check for teardown race */
 		ready = sk->sk_data_ready;
 		goto out;
 	}
 
-	tc = conn->c_transport_data;
+	tc = cp->cp_transport_data;
 	ready = tc->t_orig_data_ready;
 	rds_tcp_stats_inc(s_tcp_data_ready_calls);
 
-	if (rds_tcp_read_sock(conn, GFP_ATOMIC) == -ENOMEM)
-		queue_delayed_work(rds_wq, &conn->c_recv_w, 0);
+	if (rds_tcp_read_sock(cp, GFP_ATOMIC) == -ENOMEM)
+		queue_delayed_work(rds_wq, &cp->cp_recv_w, 0);
 out:
 	read_unlock_bh(&sk->sk_callback_lock);
 	ready(sk);
diff --git a/net/rds/tcp_send.c b/net/rds/tcp_send.c
index 618be69c9c3b..89d09b481f47 100644
--- a/net/rds/tcp_send.c
+++ b/net/rds/tcp_send.c
@@ -34,6 +34,7 @@
 #include <linux/in.h>
 #include <net/tcp.h>
 
+#include "rds_single_path.h"
 #include "rds.h"
 #include "tcp.h"
 
@@ -48,16 +49,16 @@ static void rds_tcp_cork(struct socket *sock, int val)
 	set_fs(oldfs);
 }
 
-void rds_tcp_xmit_prepare(struct rds_connection *conn)
+void rds_tcp_xmit_path_prepare(struct rds_conn_path *cp)
 {
-	struct rds_tcp_connection *tc = conn->c_transport_data;
+	struct rds_tcp_connection *tc = cp->cp_transport_data;
 
 	rds_tcp_cork(tc->t_sock, 1);
 }
 
-void rds_tcp_xmit_complete(struct rds_connection *conn)
+void rds_tcp_xmit_path_complete(struct rds_conn_path *cp)
 {
-	struct rds_tcp_connection *tc = conn->c_transport_data;
+	struct rds_tcp_connection *tc = cp->cp_transport_data;
 
 	rds_tcp_cork(tc->t_sock, 0);
 }
@@ -80,7 +81,8 @@ static int rds_tcp_sendmsg(struct socket *sock, void *data, unsigned int len)
 int rds_tcp_xmit(struct rds_connection *conn, struct rds_message *rm,
 		 unsigned int hdr_off, unsigned int sg, unsigned int off)
 {
-	struct rds_tcp_connection *tc = conn->c_transport_data;
+	struct rds_conn_path *cp = rm->m_inc.i_conn_path;
+	struct rds_tcp_connection *tc = cp->cp_transport_data;
 	int done = 0;
 	int ret = 0;
 	int more;
@@ -149,10 +151,17 @@ out:
 			rds_tcp_stats_inc(s_tcp_sndbuf_full);
 			ret = 0;
 		} else {
-			printk(KERN_WARNING "RDS/tcp: send to %pI4 "
-			       "returned %d, disconnecting and reconnecting\n",
-			       &conn->c_faddr, ret);
-			rds_conn_drop(conn);
+			/* No need to disconnect/reconnect if path_drop
+			 * has already been triggered, because, e.g., of
+			 * an incoming RST.
+			 */
+			if (rds_conn_path_up(cp)) {
+				pr_warn("RDS/tcp: send to %pI4 on cp [%d]"
+					"returned %d, "
+					"disconnecting and reconnecting\n",
+					&conn->c_faddr, cp->cp_index, ret);
+				rds_conn_path_drop(cp);
+			}
 		}
 	}
 	if (done == 0)
@@ -177,27 +186,27 @@ static int rds_tcp_is_acked(struct rds_message *rm, uint64_t ack)
 void rds_tcp_write_space(struct sock *sk)
 {
 	void (*write_space)(struct sock *sk);
-	struct rds_connection *conn;
+	struct rds_conn_path *cp;
 	struct rds_tcp_connection *tc;
 
 	read_lock_bh(&sk->sk_callback_lock);
-	conn = sk->sk_user_data;
-	if (!conn) {
+	cp = sk->sk_user_data;
+	if (!cp) {
 		write_space = sk->sk_write_space;
 		goto out;
 	}
 
-	tc = conn->c_transport_data;
+	tc = cp->cp_transport_data;
 	rdsdebug("write_space for tc %p\n", tc);
 	write_space = tc->t_orig_write_space;
 	rds_tcp_stats_inc(s_tcp_write_space_calls);
 
 	rdsdebug("tcp una %u\n", rds_tcp_snd_una(tc));
 	tc->t_last_seen_una = rds_tcp_snd_una(tc);
-	rds_send_drop_acked(conn, rds_tcp_snd_una(tc), rds_tcp_is_acked);
+	rds_send_path_drop_acked(cp, rds_tcp_snd_una(tc), rds_tcp_is_acked);
 
 	if ((atomic_read(&sk->sk_wmem_alloc) << 1) <= sk->sk_sndbuf)
-		queue_delayed_work(rds_wq, &conn->c_send_w, 0);
+		queue_delayed_work(rds_wq, &cp->cp_send_w, 0);
 
 out:
 	read_unlock_bh(&sk->sk_callback_lock);
diff --git a/net/rds/threads.c b/net/rds/threads.c
index 4a323045719b..e42df11bf30a 100644
--- a/net/rds/threads.c
+++ b/net/rds/threads.c
@@ -71,30 +71,30 @@
 struct workqueue_struct *rds_wq;
 EXPORT_SYMBOL_GPL(rds_wq);
 
-void rds_connect_path_complete(struct rds_connection *conn, int curr)
+void rds_connect_path_complete(struct rds_conn_path *cp, int curr)
 {
-	if (!rds_conn_transition(conn, curr, RDS_CONN_UP)) {
+	if (!rds_conn_path_transition(cp, curr, RDS_CONN_UP)) {
 		printk(KERN_WARNING "%s: Cannot transition to state UP, "
 				"current state is %d\n",
 				__func__,
-				atomic_read(&conn->c_state));
-		rds_conn_drop(conn);
+				atomic_read(&cp->cp_state));
+		rds_conn_path_drop(cp);
 		return;
 	}
 
 	rdsdebug("conn %p for %pI4 to %pI4 complete\n",
-	  conn, &conn->c_laddr, &conn->c_faddr);
+	  cp->cp_conn, &cp->cp_conn->c_laddr, &cp->cp_conn->c_faddr);
 
-	conn->c_reconnect_jiffies = 0;
-	set_bit(0, &conn->c_map_queued);
-	queue_delayed_work(rds_wq, &conn->c_send_w, 0);
-	queue_delayed_work(rds_wq, &conn->c_recv_w, 0);
+	cp->cp_reconnect_jiffies = 0;
+	set_bit(0, &cp->cp_conn->c_map_queued);
+	queue_delayed_work(rds_wq, &cp->cp_send_w, 0);
+	queue_delayed_work(rds_wq, &cp->cp_recv_w, 0);
 }
 EXPORT_SYMBOL_GPL(rds_connect_path_complete);
 
 void rds_connect_complete(struct rds_connection *conn)
 {
-	rds_connect_path_complete(conn, RDS_CONN_CONNECTING);
+	rds_connect_path_complete(&conn->c_path[0], RDS_CONN_CONNECTING);
 }
 EXPORT_SYMBOL_GPL(rds_connect_complete);
 
@@ -116,70 +116,87 @@ EXPORT_SYMBOL_GPL(rds_connect_complete);
  * We should *always* start with a random backoff; otherwise a broken connection
  * will always take several iterations to be re-established.
  */
-void rds_queue_reconnect(struct rds_connection *conn)
+void rds_queue_reconnect(struct rds_conn_path *cp)
 {
 	unsigned long rand;
+	struct rds_connection *conn = cp->cp_conn;
 
 	rdsdebug("conn %p for %pI4 to %pI4 reconnect jiffies %lu\n",
 	  conn, &conn->c_laddr, &conn->c_faddr,
-	  conn->c_reconnect_jiffies);
+	  cp->cp_reconnect_jiffies);
 
-	set_bit(RDS_RECONNECT_PENDING, &conn->c_flags);
-	if (conn->c_reconnect_jiffies == 0) {
-		conn->c_reconnect_jiffies = rds_sysctl_reconnect_min_jiffies;
-		queue_delayed_work(rds_wq, &conn->c_conn_w, 0);
+	/* let peer with smaller addr initiate reconnect, to avoid duels */
+	if (conn->c_trans->t_type == RDS_TRANS_TCP &&
+	    conn->c_laddr > conn->c_faddr)
+		return;
+
+	set_bit(RDS_RECONNECT_PENDING, &cp->cp_flags);
+	if (cp->cp_reconnect_jiffies == 0) {
+		cp->cp_reconnect_jiffies = rds_sysctl_reconnect_min_jiffies;
+		queue_delayed_work(rds_wq, &cp->cp_conn_w, 0);
 		return;
 	}
 
 	get_random_bytes(&rand, sizeof(rand));
 	rdsdebug("%lu delay %lu ceil conn %p for %pI4 -> %pI4\n",
-		 rand % conn->c_reconnect_jiffies, conn->c_reconnect_jiffies,
+		 rand % cp->cp_reconnect_jiffies, cp->cp_reconnect_jiffies,
 		 conn, &conn->c_laddr, &conn->c_faddr);
-	queue_delayed_work(rds_wq, &conn->c_conn_w,
-			   rand % conn->c_reconnect_jiffies);
+	queue_delayed_work(rds_wq, &cp->cp_conn_w,
+			   rand % cp->cp_reconnect_jiffies);
 
-	conn->c_reconnect_jiffies = min(conn->c_reconnect_jiffies * 2,
+	cp->cp_reconnect_jiffies = min(cp->cp_reconnect_jiffies * 2,
 					rds_sysctl_reconnect_max_jiffies);
 }
 
 void rds_connect_worker(struct work_struct *work)
 {
-	struct rds_connection *conn = container_of(work, struct rds_connection, c_conn_w.work);
+	struct rds_conn_path *cp = container_of(work,
+						struct rds_conn_path,
+						cp_conn_w.work);
+	struct rds_connection *conn = cp->cp_conn;
 	int ret;
 
-	clear_bit(RDS_RECONNECT_PENDING, &conn->c_flags);
-	if (rds_conn_transition(conn, RDS_CONN_DOWN, RDS_CONN_CONNECTING)) {
-		ret = conn->c_trans->conn_connect(conn);
+	if (cp->cp_index > 1 && cp->cp_conn->c_laddr > cp->cp_conn->c_faddr)
+		return;
+	clear_bit(RDS_RECONNECT_PENDING, &cp->cp_flags);
+	ret = rds_conn_path_transition(cp, RDS_CONN_DOWN, RDS_CONN_CONNECTING);
+	if (ret) {
+		ret = conn->c_trans->conn_path_connect(cp);
 		rdsdebug("conn %p for %pI4 to %pI4 dispatched, ret %d\n",
 			conn, &conn->c_laddr, &conn->c_faddr, ret);
 
 		if (ret) {
-			if (rds_conn_transition(conn, RDS_CONN_CONNECTING, RDS_CONN_DOWN))
-				rds_queue_reconnect(conn);
+			if (rds_conn_path_transition(cp,
+						     RDS_CONN_CONNECTING,
+						     RDS_CONN_DOWN))
+				rds_queue_reconnect(cp);
 			else
-				rds_conn_error(conn, "RDS: connect failed\n");
+				rds_conn_path_error(cp,
+						    "RDS: connect failed\n");
 		}
 	}
 }
 
 void rds_send_worker(struct work_struct *work)
 {
-	struct rds_connection *conn = container_of(work, struct rds_connection, c_send_w.work);
+	struct rds_conn_path *cp = container_of(work,
+						struct rds_conn_path,
+						cp_send_w.work);
 	int ret;
 
-	if (rds_conn_state(conn) == RDS_CONN_UP) {
-		clear_bit(RDS_LL_SEND_FULL, &conn->c_flags);
-		ret = rds_send_xmit(conn);
+	if (rds_conn_path_state(cp) == RDS_CONN_UP) {
+		clear_bit(RDS_LL_SEND_FULL, &cp->cp_flags);
+		ret = rds_send_xmit(cp);
 		cond_resched();
-		rdsdebug("conn %p ret %d\n", conn, ret);
+		rdsdebug("conn %p ret %d\n", cp->cp_conn, ret);
 		switch (ret) {
 		case -EAGAIN:
 			rds_stats_inc(s_send_immediate_retry);
-			queue_delayed_work(rds_wq, &conn->c_send_w, 0);
+			queue_delayed_work(rds_wq, &cp->cp_send_w, 0);
 			break;
 		case -ENOMEM:
 			rds_stats_inc(s_send_delayed_retry);
-			queue_delayed_work(rds_wq, &conn->c_send_w, 2);
+			queue_delayed_work(rds_wq, &cp->cp_send_w, 2);
 		default:
 			break;
 		}
@@ -188,20 +205,22 @@ void rds_send_worker(struct work_struct *work)
 
 void rds_recv_worker(struct work_struct *work)
 {
-	struct rds_connection *conn = container_of(work, struct rds_connection, c_recv_w.work);
+	struct rds_conn_path *cp = container_of(work,
+						struct rds_conn_path,
+						cp_recv_w.work);
 	int ret;
 
-	if (rds_conn_state(conn) == RDS_CONN_UP) {
-		ret = conn->c_trans->recv(conn);
-		rdsdebug("conn %p ret %d\n", conn, ret);
+	if (rds_conn_path_state(cp) == RDS_CONN_UP) {
+		ret = cp->cp_conn->c_trans->recv_path(cp);
+		rdsdebug("conn %p ret %d\n", cp->cp_conn, ret);
 		switch (ret) {
 		case -EAGAIN:
 			rds_stats_inc(s_recv_immediate_retry);
-			queue_delayed_work(rds_wq, &conn->c_recv_w, 0);
+			queue_delayed_work(rds_wq, &cp->cp_recv_w, 0);
 			break;
 		case -ENOMEM:
 			rds_stats_inc(s_recv_delayed_retry);
-			queue_delayed_work(rds_wq, &conn->c_recv_w, 2);
+			queue_delayed_work(rds_wq, &cp->cp_recv_w, 2);
 		default:
 			break;
 		}
@@ -210,9 +229,11 @@ void rds_recv_worker(struct work_struct *work)
 
 void rds_shutdown_worker(struct work_struct *work)
 {
-	struct rds_connection *conn = container_of(work, struct rds_connection, c_down_w);
+	struct rds_conn_path *cp = container_of(work,
+						struct rds_conn_path,
+						cp_down_w);
 
-	rds_conn_shutdown(conn);
+	rds_conn_shutdown(cp);
 }
 
 void rds_threads_exit(void)