1 files changed, 204 insertions, 152 deletions

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);
+}