diff --git a/net/tipc/socket.c b/net/tipc/socket.c
index 94bd286..1262889 100644
--- a/net/tipc/socket.c
+++ b/net/tipc/socket.c
@@ -96,9 +96,11 @@
 	uint conn_timeout;
 	atomic_t dupl_rcvcnt;
 	bool link_cong;
-	uint sent_unacked;
-	uint rcv_unacked;
+	u16 snt_unacked;
+	u16 snd_win;
 	u16 peer_caps;
+	u16 rcv_unacked;
+	u16 rcv_win;
 	struct sockaddr_tipc remote;
 	struct rhash_head node;
 	struct rcu_head rcu;
@@ -228,9 +230,29 @@
 	return container_of(sk, struct tipc_sock, sk);
 }
 
-static int tsk_conn_cong(struct tipc_sock *tsk)
+static bool tsk_conn_cong(struct tipc_sock *tsk)
 {
-	return tsk->sent_unacked >= TIPC_FLOWCTRL_WIN;
+	return tsk->snt_unacked >= tsk->snd_win;
+}
+
+/* tsk_blocks(): translate a buffer size in bytes to number of
+ * advertisable blocks, taking into account the ratio truesize(len)/len
+ * We can trust that this ratio is always < 4 for len >= FLOWCTL_BLK_SZ
+ */
+static u16 tsk_adv_blocks(int len)
+{
+	return len / FLOWCTL_BLK_SZ / 4;
+}
+
+/* tsk_inc(): increment counter for sent or received data
+ * - If block based flow control is not supported by peer we
+ *   fall back to message based ditto, incrementing the counter
+ */
+static u16 tsk_inc(struct tipc_sock *tsk, int msglen)
+{
+	if (likely(tsk->peer_caps & TIPC_BLOCK_FLOWCTL))
+		return ((msglen / FLOWCTL_BLK_SZ) + 1);
+	return 1;
 }
 
 /**
@@ -378,9 +400,12 @@
 	sk->sk_write_space = tipc_write_space;
 	sk->sk_destruct = tipc_sock_destruct;
 	tsk->conn_timeout = CONN_TIMEOUT_DEFAULT;
-	tsk->sent_unacked = 0;
 	atomic_set(&tsk->dupl_rcvcnt, 0);
 
+	/* Start out with safe limits until we receive an advertised window */
+	tsk->snd_win = tsk_adv_blocks(RCVBUF_MIN);
+	tsk->rcv_win = tsk->snd_win;
+
 	if (sock->state == SS_READY) {
 		tsk_set_unreturnable(tsk, true);
 		if (sock->type == SOCK_DGRAM)
@@ -776,7 +801,7 @@
 	struct sock *sk = &tsk->sk;
 	struct tipc_msg *hdr = buf_msg(skb);
 	int mtyp = msg_type(hdr);
-	int conn_cong;
+	bool conn_cong;
 
 	/* Ignore if connection cannot be validated: */
 	if (!tsk_peer_msg(tsk, hdr))
@@ -790,7 +815,9 @@
 		return;
 	} else if (mtyp == CONN_ACK) {
 		conn_cong = tsk_conn_cong(tsk);
-		tsk->sent_unacked -= msg_msgcnt(hdr);
+		tsk->snt_unacked -= msg_conn_ack(hdr);
+		if (tsk->peer_caps & TIPC_BLOCK_FLOWCTL)
+			tsk->snd_win = msg_adv_win(hdr);
 		if (conn_cong)
 			sk->sk_write_space(sk);
 	} else if (mtyp != CONN_PROBE_REPLY) {
@@ -1021,12 +1048,14 @@
 	u32 dnode;
 	uint mtu, send, sent = 0;
 	struct iov_iter save;
+	int hlen = MIN_H_SIZE;
 
 	/* Handle implied connection establishment */
 	if (unlikely(dest)) {
 		rc = __tipc_sendmsg(sock, m, dsz);
+		hlen = msg_hdr_sz(mhdr);
 		if (dsz && (dsz == rc))
-			tsk->sent_unacked = 1;
+			tsk->snt_unacked = tsk_inc(tsk, dsz + hlen);
 		return rc;
 	}
 	if (dsz > (uint)INT_MAX)
@@ -1055,7 +1084,7 @@
 		if (likely(!tsk_conn_cong(tsk))) {
 			rc = tipc_node_xmit(net, &pktchain, dnode, portid);
 			if (likely(!rc)) {
-				tsk->sent_unacked++;
+				tsk->snt_unacked += tsk_inc(tsk, send + hlen);
 				sent += send;
 				if (sent == dsz)
 					return dsz;
@@ -1120,6 +1149,12 @@
 	tipc_node_add_conn(net, peer_node, tsk->portid, peer_port);
 	tsk->max_pkt = tipc_node_get_mtu(net, peer_node, tsk->portid);
 	tsk->peer_caps = tipc_node_get_capabilities(net, peer_node);
+	if (tsk->peer_caps & TIPC_BLOCK_FLOWCTL)
+		return;
+
+	/* Fall back to message based flow control */
+	tsk->rcv_win = FLOWCTL_MSG_WIN;
+	tsk->snd_win = FLOWCTL_MSG_WIN;
 }
 
 /**
@@ -1216,7 +1251,7 @@
 	return 0;
 }
 
-static void tipc_sk_send_ack(struct tipc_sock *tsk, uint ack)
+static void tipc_sk_send_ack(struct tipc_sock *tsk)
 {
 	struct net *net = sock_net(&tsk->sk);
 	struct sk_buff *skb = NULL;
@@ -1232,7 +1267,14 @@
 	if (!skb)
 		return;
 	msg = buf_msg(skb);
-	msg_set_msgcnt(msg, ack);
+	msg_set_conn_ack(msg, tsk->rcv_unacked);
+	tsk->rcv_unacked = 0;
+
+	/* Adjust to and advertize the correct window limit */
+	if (tsk->peer_caps & TIPC_BLOCK_FLOWCTL) {
+		tsk->rcv_win = tsk_adv_blocks(tsk->sk.sk_rcvbuf);
+		msg_set_adv_win(msg, tsk->rcv_win);
+	}
 	tipc_node_xmit_skb(net, skb, dnode, msg_link_selector(msg));
 }
 
@@ -1290,7 +1332,7 @@
 	long timeo;
 	unsigned int sz;
 	u32 err;
-	int res;
+	int res, hlen;
 
 	/* Catch invalid receive requests */
 	if (unlikely(!buf_len))
@@ -1315,6 +1357,7 @@
 	buf = skb_peek(&sk->sk_receive_queue);
 	msg = buf_msg(buf);
 	sz = msg_data_sz(msg);
+	hlen = msg_hdr_sz(msg);
 	err = msg_errcode(msg);
 
 	/* Discard an empty non-errored message & try again */
@@ -1337,7 +1380,7 @@
 			sz = buf_len;
 			m->msg_flags |= MSG_TRUNC;
 		}
-		res = skb_copy_datagram_msg(buf, msg_hdr_sz(msg), m, sz);
+		res = skb_copy_datagram_msg(buf, hlen, m, sz);
 		if (res)
 			goto exit;
 		res = sz;
@@ -1349,15 +1392,15 @@
 			res = -ECONNRESET;
 	}
 
-	/* Consume received message (optional) */
-	if (likely(!(flags & MSG_PEEK))) {
-		if ((sock->state != SS_READY) &&
-		    (++tsk->rcv_unacked >= TIPC_CONNACK_INTV)) {
-			tipc_sk_send_ack(tsk, tsk->rcv_unacked);
-			tsk->rcv_unacked = 0;
-		}
-		tsk_advance_rx_queue(sk);
+	if (unlikely(flags & MSG_PEEK))
+		goto exit;
+
+	if (likely(sock->state != SS_READY)) {
+		tsk->rcv_unacked += tsk_inc(tsk, hlen + sz);
+		if (unlikely(tsk->rcv_unacked >= (tsk->rcv_win / 4)))
+			tipc_sk_send_ack(tsk);
 	}
+	tsk_advance_rx_queue(sk);
 exit:
 	release_sock(sk);
 	return res;
@@ -1386,7 +1429,7 @@
 	int sz_to_copy, target, needed;
 	int sz_copied = 0;
 	u32 err;
-	int res = 0;
+	int res = 0, hlen;
 
 	/* Catch invalid receive attempts */
 	if (unlikely(!buf_len))
@@ -1412,6 +1455,7 @@
 	buf = skb_peek(&sk->sk_receive_queue);
 	msg = buf_msg(buf);
 	sz = msg_data_sz(msg);
+	hlen = msg_hdr_sz(msg);
 	err = msg_errcode(msg);
 
 	/* Discard an empty non-errored message & try again */
@@ -1436,8 +1480,7 @@
 		needed = (buf_len - sz_copied);
 		sz_to_copy = (sz <= needed) ? sz : needed;
 
-		res = skb_copy_datagram_msg(buf, msg_hdr_sz(msg) + offset,
-					    m, sz_to_copy);
+		res = skb_copy_datagram_msg(buf, hlen + offset, m, sz_to_copy);
 		if (res)
 			goto exit;
 
@@ -1459,20 +1502,18 @@
 			res = -ECONNRESET;
 	}
 
-	/* Consume received message (optional) */
-	if (likely(!(flags & MSG_PEEK))) {
-		if (unlikely(++tsk->rcv_unacked >= TIPC_CONNACK_INTV)) {
-			tipc_sk_send_ack(tsk, tsk->rcv_unacked);
-			tsk->rcv_unacked = 0;
-		}
-		tsk_advance_rx_queue(sk);
-	}
+	if (unlikely(flags & MSG_PEEK))
+		goto exit;
+
+	tsk->rcv_unacked += tsk_inc(tsk, hlen + sz);
+	if (unlikely(tsk->rcv_unacked >= (tsk->rcv_win / 4)))
+		tipc_sk_send_ack(tsk);
+	tsk_advance_rx_queue(sk);
 
 	/* Loop around if more data is required */
 	if ((sz_copied < buf_len) &&	/* didn't get all requested data */
 	    (!skb_queue_empty(&sk->sk_receive_queue) ||
 	    (sz_copied < target)) &&	/* and more is ready or required */
-	    (!(flags & MSG_PEEK)) &&	/* and aren't just peeking at data */
 	    (!err))			/* and haven't reached a FIN */
 		goto restart;
 
@@ -1604,30 +1645,33 @@
 /**
  * rcvbuf_limit - get proper overload limit of socket receive queue
  * @sk: socket
- * @buf: message
+ * @skb: message
  *
- * For all connection oriented messages, irrespective of importance,
- * the default overload value (i.e. 67MB) is set as limit.
+ * For connection oriented messages, irrespective of importance,
+ * default queue limit is 2 MB.
  *
- * For all connectionless messages, by default new queue limits are
- * as belows:
+ * For connectionless messages, queue limits are based on message
+ * importance as follows:
  *
- * TIPC_LOW_IMPORTANCE       (4 MB)
- * TIPC_MEDIUM_IMPORTANCE    (8 MB)
- * TIPC_HIGH_IMPORTANCE      (16 MB)
- * TIPC_CRITICAL_IMPORTANCE  (32 MB)
+ * TIPC_LOW_IMPORTANCE       (2 MB)
+ * TIPC_MEDIUM_IMPORTANCE    (4 MB)
+ * TIPC_HIGH_IMPORTANCE      (8 MB)
+ * TIPC_CRITICAL_IMPORTANCE  (16 MB)
  *
  * Returns overload limit according to corresponding message importance
  */
-static unsigned int rcvbuf_limit(struct sock *sk, struct sk_buff *buf)
+static unsigned int rcvbuf_limit(struct sock *sk, struct sk_buff *skb)
 {
-	struct tipc_msg *msg = buf_msg(buf);
+	struct tipc_sock *tsk = tipc_sk(sk);
+	struct tipc_msg *hdr = buf_msg(skb);
 
-	if (msg_connected(msg))
-		return sysctl_tipc_rmem[2];
+	if (unlikely(!msg_connected(hdr)))
+		return sk->sk_rcvbuf << msg_importance(hdr);
 
-	return sk->sk_rcvbuf >> TIPC_CRITICAL_IMPORTANCE <<
-		msg_importance(msg);
+	if (likely(tsk->peer_caps & TIPC_BLOCK_FLOWCTL))
+		return sk->sk_rcvbuf;
+
+	return FLOWCTL_MSG_LIM;
 }
 
 /**