tipc: split link outqueue

struct tipc_link contains one single queue for outgoing packets,
where both transmitted and waiting packets are queued.

This infrastructure is hard to maintain, because we need
to keep a number of fields to keep track of which packets are
sent or unsent, and the number of packets in each category.

A lot of code becomes simpler if we split this queue into a transmission
queue, where sent/unacknowledged packets are kept, and a backlog queue,
where we keep the not yet sent packets.

In this commit we do this separation.

Reviewed-by: Erik Hugne <erik.hugne@ericsson.com>
Reviewed-by: Ying Xue <ying.xue@windriver.com>
Signed-off-by: Jon Maloy <jon.maloy@ericsson.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

7 files changed, 150 insertions, 167 deletions

diff --git a/net/tipc/bcast.c b/net/tipc/bcast.c
index 5ee5076a8b27..17cb0ff5f344 100644
--- a/net/tipc/bcast.c
+++ b/net/tipc/bcast.c
@@ -135,9 +135,10 @@ static void bclink_set_last_sent(struct net *net)
 {
 	struct tipc_net *tn = net_generic(net, tipc_net_id);
 	struct tipc_link *bcl = tn->bcl;
+	struct sk_buff *skb = skb_peek(&bcl->backlogq);
 
-	if (bcl->next_out)
-		bcl->fsm_msg_cnt = mod(buf_seqno(bcl->next_out) - 1);
+	if (skb)
+		bcl->fsm_msg_cnt = mod(buf_seqno(skb) - 1);
 	else
 		bcl->fsm_msg_cnt = mod(bcl->next_out_no - 1);
 }
@@ -180,7 +181,7 @@ static void bclink_retransmit_pkt(struct tipc_net *tn, u32 after, u32 to)
 	struct sk_buff *skb;
 	struct tipc_link *bcl = tn->bcl;
 
-	skb_queue_walk(&bcl->outqueue, skb) {
+	skb_queue_walk(&bcl->transmq, skb) {
 		if (more(buf_seqno(skb), after)) {
 			tipc_link_retransmit(bcl, skb, mod(to - after));
 			break;
@@ -210,7 +211,6 @@ void tipc_bclink_wakeup_users(struct net *net)
 void tipc_bclink_acknowledge(struct tipc_node *n_ptr, u32 acked)
 {
 	struct sk_buff *skb, *tmp;
-	struct sk_buff *next;
 	unsigned int released = 0;
 	struct net *net = n_ptr->net;
 	struct tipc_net *tn = net_generic(net, tipc_net_id);
@@ -221,7 +221,7 @@ void tipc_bclink_acknowledge(struct tipc_node *n_ptr, u32 acked)
 	tipc_bclink_lock(net);
 
 	/* Bail out if tx queue is empty (no clean up is required) */
-	skb = skb_peek(&tn->bcl->outqueue);
+	skb = skb_peek(&tn->bcl->transmq);
 	if (!skb)
 		goto exit;
 
@@ -248,27 +248,19 @@ void tipc_bclink_acknowledge(struct tipc_node *n_ptr, u32 acked)
 	}
 
 	/* Skip over packets that node has previously acknowledged */
-	skb_queue_walk(&tn->bcl->outqueue, skb) {
+	skb_queue_walk(&tn->bcl->transmq, skb) {
 		if (more(buf_seqno(skb), n_ptr->bclink.acked))
 			break;
 	}
 
 	/* Update packets that node is now acknowledging */
-	skb_queue_walk_from_safe(&tn->bcl->outqueue, skb, tmp) {
+	skb_queue_walk_from_safe(&tn->bcl->transmq, skb, tmp) {
 		if (more(buf_seqno(skb), acked))
 			break;
-
-		next = tipc_skb_queue_next(&tn->bcl->outqueue, skb);
-		if (skb != tn->bcl->next_out) {
-			bcbuf_decr_acks(skb);
-		} else {
-			bcbuf_set_acks(skb, 0);
-			tn->bcl->next_out = next;
-			bclink_set_last_sent(net);
-		}
-
+		bcbuf_decr_acks(skb);
+		bclink_set_last_sent(net);
 		if (bcbuf_acks(skb) == 0) {
-			__skb_unlink(skb, &tn->bcl->outqueue);
+			__skb_unlink(skb, &tn->bcl->transmq);
 			kfree_skb(skb);
 			released = 1;
 		}
@@ -276,7 +268,7 @@ void tipc_bclink_acknowledge(struct tipc_node *n_ptr, u32 acked)
 	n_ptr->bclink.acked = acked;
 
 	/* Try resolving broadcast link congestion, if necessary */
-	if (unlikely(tn->bcl->next_out)) {
+	if (unlikely(skb_peek(&tn->bcl->backlogq))) {
 		tipc_link_push_packets(tn->bcl);
 		bclink_set_last_sent(net);
 	}
@@ -323,7 +315,7 @@ void tipc_bclink_update_link_state(struct tipc_node *n_ptr,
 	buf = tipc_buf_acquire(INT_H_SIZE);
 	if (buf) {
 		struct tipc_msg *msg = buf_msg(buf);
-		struct sk_buff *skb = skb_peek(&n_ptr->bclink.deferred_queue);
+		struct sk_buff *skb = skb_peek(&n_ptr->bclink.deferdq);
 		u32 to = skb ? buf_seqno(skb) - 1 : n_ptr->bclink.last_sent;
 
 		tipc_msg_init(tn->own_addr, msg, BCAST_PROTOCOL, STATE_MSG,
@@ -398,7 +390,7 @@ int tipc_bclink_xmit(struct net *net, struct sk_buff_head *list)
 		if (likely(bclink->bcast_nodes.count)) {
 			rc = __tipc_link_xmit(net, bcl, list);
 			if (likely(!rc)) {
-				u32 len = skb_queue_len(&bcl->outqueue);
+				u32 len = skb_queue_len(&bcl->transmq);
 
 				bclink_set_last_sent(net);
 				bcl->stats.queue_sz_counts++;
@@ -563,25 +555,25 @@ receive:
 		if (node->bclink.last_in == node->bclink.last_sent)
 			goto unlock;
 
-		if (skb_queue_empty(&node->bclink.deferred_queue)) {
+		if (skb_queue_empty(&node->bclink.deferdq)) {
 			node->bclink.oos_state = 1;
 			goto unlock;
 		}
 
-		msg = buf_msg(skb_peek(&node->bclink.deferred_queue));
+		msg = buf_msg(skb_peek(&node->bclink.deferdq));
 		seqno = msg_seqno(msg);
 		next_in = mod(next_in + 1);
 		if (seqno != next_in)
 			goto unlock;
 
 		/* Take in-sequence message from deferred queue & deliver it */
-		buf = __skb_dequeue(&node->bclink.deferred_queue);
+		buf = __skb_dequeue(&node->bclink.deferdq);
 		goto receive;
 	}
 
 	/* Handle out-of-sequence broadcast message */
 	if (less(next_in, seqno)) {
-		deferred = tipc_link_defer_pkt(&node->bclink.deferred_queue,
+		deferred = tipc_link_defer_pkt(&node->bclink.deferdq,
 					       buf);
 		bclink_update_last_sent(node, seqno);
 		buf = NULL;
@@ -638,7 +630,6 @@ static int tipc_bcbearer_send(struct net *net, struct sk_buff *buf,
 		msg_set_non_seq(msg, 1);
 		msg_set_mc_netid(msg, tn->net_id);
 		tn->bcl->stats.sent_info++;
-
 		if (WARN_ON(!bclink->bcast_nodes.count)) {
 			dump_stack();
 			return 0;
@@ -917,8 +908,9 @@ int tipc_bclink_init(struct net *net)
 	sprintf(bcbearer->media.name, "tipc-broadcast");
 
 	spin_lock_init(&bclink->lock);
-	__skb_queue_head_init(&bcl->outqueue);
-	__skb_queue_head_init(&bcl->deferred_queue);
+	__skb_queue_head_init(&bcl->transmq);
+	__skb_queue_head_init(&bcl->backlogq);
+	__skb_queue_head_init(&bcl->deferdq);
 	skb_queue_head_init(&bcl->wakeupq);
 	bcl->next_out_no = 1;
 	spin_lock_init(&bclink->node.lock);
diff --git a/net/tipc/link.c b/net/tipc/link.c
index 2652c3286e2f..7e0036f5a364 100644
--- a/net/tipc/link.c
+++ b/net/tipc/link.c
@@ -194,10 +194,10 @@ static void link_timeout(unsigned long data)
 	tipc_node_lock(l_ptr->owner);
 
 	/* update counters used in statistical profiling of send traffic */
-	l_ptr->stats.accu_queue_sz += skb_queue_len(&l_ptr->outqueue);
+	l_ptr->stats.accu_queue_sz += skb_queue_len(&l_ptr->transmq);
 	l_ptr->stats.queue_sz_counts++;
 
-	skb = skb_peek(&l_ptr->outqueue);
+	skb = skb_peek(&l_ptr->transmq);
 	if (skb) {
 		struct tipc_msg *msg = buf_msg(skb);
 		u32 length = msg_size(msg);
@@ -229,7 +229,7 @@ static void link_timeout(unsigned long data)
 	/* do all other link processing performed on a periodic basis */
 	link_state_event(l_ptr, TIMEOUT_EVT);
 
-	if (l_ptr->next_out)
+	if (skb_queue_len(&l_ptr->backlogq))
 		tipc_link_push_packets(l_ptr);
 
 	tipc_node_unlock(l_ptr->owner);
@@ -313,8 +313,9 @@ struct tipc_link *tipc_link_create(struct tipc_node *n_ptr,
 	link_init_max_pkt(l_ptr);
 
 	l_ptr->next_out_no = 1;
-	__skb_queue_head_init(&l_ptr->outqueue);
-	__skb_queue_head_init(&l_ptr->deferred_queue);
+	__skb_queue_head_init(&l_ptr->transmq);
+	__skb_queue_head_init(&l_ptr->backlogq);
+	__skb_queue_head_init(&l_ptr->deferdq);
 	skb_queue_head_init(&l_ptr->wakeupq);
 	skb_queue_head_init(&l_ptr->inputq);
 	skb_queue_head_init(&l_ptr->namedq);
@@ -400,7 +401,7 @@ static bool link_schedule_user(struct tipc_link *link, u32 oport,
  */
 void link_prepare_wakeup(struct tipc_link *link)
 {
-	uint pend_qsz = skb_queue_len(&link->outqueue);
+	uint pend_qsz = skb_queue_len(&link->backlogq);
 	struct sk_buff *skb, *tmp;
 
 	skb_queue_walk_safe(&link->wakeupq, skb, tmp) {
@@ -430,8 +431,9 @@ void tipc_link_reset_fragments(struct tipc_link *l_ptr)
  */
 void tipc_link_purge_queues(struct tipc_link *l_ptr)
 {
-	__skb_queue_purge(&l_ptr->deferred_queue);
-	__skb_queue_purge(&l_ptr->outqueue);
+	__skb_queue_purge(&l_ptr->deferdq);
+	__skb_queue_purge(&l_ptr->transmq);
+	__skb_queue_purge(&l_ptr->backlogq);
 	tipc_link_reset_fragments(l_ptr);
 }
 
@@ -464,15 +466,15 @@ void tipc_link_reset(struct tipc_link *l_ptr)
 	}
 
 	/* Clean up all queues, except inputq: */
-	__skb_queue_purge(&l_ptr->outqueue);
-	__skb_queue_purge(&l_ptr->deferred_queue);
+	__skb_queue_purge(&l_ptr->transmq);
+	__skb_queue_purge(&l_ptr->backlogq);
+	__skb_queue_purge(&l_ptr->deferdq);
 	if (!owner->inputq)
 		owner->inputq = &l_ptr->inputq;
 	skb_queue_splice_init(&l_ptr->wakeupq, owner->inputq);
 	if (!skb_queue_empty(owner->inputq))
 		owner->action_flags |= TIPC_MSG_EVT;
-	l_ptr->next_out = NULL;
-	l_ptr->unacked_window = 0;
+	l_ptr->rcv_unacked = 0;
 	l_ptr->checkpoint = 1;
 	l_ptr->next_out_no = 1;
 	l_ptr->fsm_msg_cnt = 0;
@@ -742,54 +744,51 @@ int __tipc_link_xmit(struct net *net, struct tipc_link *link,
 		     struct sk_buff_head *list)
 {
 	struct tipc_msg *msg = buf_msg(skb_peek(list));
-	uint psz = msg_size(msg);
-	uint sndlim = link->queue_limit[0];
+	unsigned int maxwin = link->window;
 	uint imp = tipc_msg_tot_importance(msg);
 	uint mtu = link->max_pkt;
 	uint ack = mod(link->next_in_no - 1);
 	uint seqno = link->next_out_no;
 	uint bc_last_in = link->owner->bclink.last_in;
 	struct tipc_media_addr *addr = &link->media_addr;
-	struct sk_buff_head *outqueue = &link->outqueue;
+	struct sk_buff_head *transmq = &link->transmq;
+	struct sk_buff_head *backlogq = &link->backlogq;
 	struct sk_buff *skb, *tmp;
 
 	/* Match queue limits against msg importance: */
-	if (unlikely(skb_queue_len(outqueue) >= link->queue_limit[imp]))
+	if (unlikely(skb_queue_len(backlogq) >= link->queue_limit[imp]))
 		return tipc_link_cong(link, list);
 
 	/* Has valid packet limit been used ? */
-	if (unlikely(psz > mtu)) {
+	if (unlikely(msg_size(msg) > mtu)) {
 		__skb_queue_purge(list);
 		return -EMSGSIZE;
 	}
 
-	/* Prepare each packet for sending, and add to outqueue: */
+	/* Prepare each packet for sending, and add to relevant queue: */
 	skb_queue_walk_safe(list, skb, tmp) {
 		__skb_unlink(skb, list);
 		msg = buf_msg(skb);
-		msg_set_word(msg, 2, ((ack << 16) | mod(seqno)));
+		msg_set_seqno(msg, seqno);
+		msg_set_ack(msg, ack);
 		msg_set_bcast_ack(msg, bc_last_in);
 
-		if (skb_queue_len(outqueue) < sndlim) {
-			__skb_queue_tail(outqueue, skb);
-			tipc_bearer_send(net, link->bearer_id,
-					 skb, addr);
-			link->next_out = NULL;
-			link->unacked_window = 0;
-		} else if (tipc_msg_bundle(outqueue, skb, mtu)) {
+		if (likely(skb_queue_len(transmq) < maxwin)) {
+			__skb_queue_tail(transmq, skb);
+			tipc_bearer_send(net, link->bearer_id, skb, addr);
+			link->rcv_unacked = 0;
+			seqno++;
+			continue;
+		}
+		if (tipc_msg_bundle(skb_peek_tail(backlogq), skb, mtu)) {
 			link->stats.sent_bundled++;
 			continue;
-		} else if (tipc_msg_make_bundle(outqueue, skb, mtu,
-						link->addr)) {
+		}
+		if (tipc_msg_make_bundle(&skb, mtu, link->addr)) {
 			link->stats.sent_bundled++;
 			link->stats.sent_bundles++;
-			if (!link->next_out)
-				link->next_out = skb_peek_tail(outqueue);
-		} else {
-			__skb_queue_tail(outqueue, skb);
-			if (!link->next_out)
-				link->next_out = skb;
 		}
+		__skb_queue_tail(backlogq, skb);
 		seqno++;
 	}
 	link->next_out_no = seqno;
@@ -895,14 +894,6 @@ static void tipc_link_sync_rcv(struct tipc_node *n, struct sk_buff *buf)
 	kfree_skb(buf);
 }
 
-struct sk_buff *tipc_skb_queue_next(const struct sk_buff_head *list,
-				    const struct sk_buff *skb)
-{
-	if (skb_queue_is_last(list, skb))
-		return NULL;
-	return skb->next;
-}
-
 /*
  * tipc_link_push_packets - push unsent packets to bearer
  *
@@ -911,30 +902,23 @@ struct sk_buff *tipc_skb_queue_next(const struct sk_buff_head *list,
  *
  * Called with node locked
  */
-void tipc_link_push_packets(struct tipc_link *l_ptr)
+void tipc_link_push_packets(struct tipc_link *link)
 {
-	struct sk_buff_head *outqueue = &l_ptr->outqueue;
-	struct sk_buff *skb = l_ptr->next_out;
+	struct sk_buff *skb;
 	struct tipc_msg *msg;
-	u32 next, first;
+	unsigned int ack = mod(link->next_in_no - 1);
 
-	skb_queue_walk_from(outqueue, skb) {
-		msg = buf_msg(skb);
-		next = msg_seqno(msg);
-		first = buf_seqno(skb_peek(outqueue));
-
-		if (mod(next - first) < l_ptr->queue_limit[0]) {
-			msg_set_ack(msg, mod(l_ptr->next_in_no - 1));
-			msg_set_bcast_ack(msg, l_ptr->owner->bclink.last_in);
-			if (msg_user(msg) == MSG_BUNDLER)
-				TIPC_SKB_CB(skb)->bundling = false;
-			tipc_bearer_send(l_ptr->owner->net,
-					 l_ptr->bearer_id, skb,
-					 &l_ptr->media_addr);
-			l_ptr->next_out = tipc_skb_queue_next(outqueue, skb);
-		} else {
+	while (skb_queue_len(&link->transmq) < link->window) {
+		skb = __skb_dequeue(&link->backlogq);
+		if (!skb)
 			break;
-		}
+		msg = buf_msg(skb);
+		msg_set_ack(msg, ack);
+		msg_set_bcast_ack(msg, link->owner->bclink.last_in);
+		link->rcv_unacked = 0;
+		__skb_queue_tail(&link->transmq, skb);
+		tipc_bearer_send(link->owner->net, link->bearer_id,
+				 skb, &link->media_addr);
 	}
 }
 
@@ -1021,8 +1005,8 @@ void tipc_link_retransmit(struct tipc_link *l_ptr, struct sk_buff *skb,
 		l_ptr->stale_count = 1;
 	}
 
-	skb_queue_walk_from(&l_ptr->outqueue, skb) {
-		if (!retransmits || skb == l_ptr->next_out)
+	skb_queue_walk_from(&l_ptr->transmq, skb) {
+		if (!retransmits)
 			break;
 		msg = buf_msg(skb);
 		msg_set_ack(msg, mod(l_ptr->next_in_no - 1));
@@ -1039,12 +1023,12 @@ static void link_retrieve_defq(struct tipc_link *link,
 {
 	u32 seq_no;
 
-	if (skb_queue_empty(&link->deferred_queue))
+	if (skb_queue_empty(&link->deferdq))
 		return;
 
-	seq_no = buf_seqno(skb_peek(&link->deferred_queue));
+	seq_no = buf_seqno(skb_peek(&link->deferdq));
 	if (seq_no == mod(link->next_in_no))
-		skb_queue_splice_tail_init(&link->deferred_queue, list);
+		skb_queue_splice_tail_init(&link->deferdq, list);
 }
 
 /**
@@ -1121,17 +1105,16 @@ void tipc_rcv(struct net *net, struct sk_buff *skb, struct tipc_bearer *b_ptr)
 			tipc_bclink_acknowledge(n_ptr, msg_bcast_ack(msg));
 
 		released = 0;
-		skb_queue_walk_safe(&l_ptr->outqueue, skb1, tmp) {
-			if (skb1 == l_ptr->next_out ||
-			    more(buf_seqno(skb1), ackd))
+		skb_queue_walk_safe(&l_ptr->transmq, skb1, tmp) {
+			if (more(buf_seqno(skb1), ackd))
 				break;
-			 __skb_unlink(skb1, &l_ptr->outqueue);
+			 __skb_unlink(skb1, &l_ptr->transmq);
 			 kfree_skb(skb1);
 			 released = 1;
 		}
 
 		/* Try sending any messages link endpoint has pending */
-		if (unlikely(l_ptr->next_out))
+		if (unlikely(skb_queue_len(&l_ptr->backlogq)))
 			tipc_link_push_packets(l_ptr);
 
 		if (released && !skb_queue_empty(&l_ptr->wakeupq))
@@ -1166,10 +1149,9 @@ void tipc_rcv(struct net *net, struct sk_buff *skb, struct tipc_bearer *b_ptr)
 			goto unlock;
 		}
 		l_ptr->next_in_no++;
-		if (unlikely(!skb_queue_empty(&l_ptr->deferred_queue)))
+		if (unlikely(!skb_queue_empty(&l_ptr->deferdq)))
 			link_retrieve_defq(l_ptr, &head);
-
-		if (unlikely(++l_ptr->unacked_window >= TIPC_MIN_LINK_WIN)) {
+		if (unlikely(++l_ptr->rcv_unacked >= TIPC_MIN_LINK_WIN)) {
 			l_ptr->stats.sent_acks++;
 			tipc_link_proto_xmit(l_ptr, STATE_MSG, 0, 0, 0, 0, 0);
 		}
@@ -1336,9 +1318,9 @@ static void link_handle_out_of_seq_msg(struct tipc_link *l_ptr,
 		return;
 	}
 
-	if (tipc_link_defer_pkt(&l_ptr->deferred_queue, buf)) {
+	if (tipc_link_defer_pkt(&l_ptr->deferdq, buf)) {
 		l_ptr->stats.deferred_recv++;
-		if ((skb_queue_len(&l_ptr->deferred_queue) % 16) == 1)
+		if ((skb_queue_len(&l_ptr->deferdq) % TIPC_MIN_LINK_WIN) == 1)
 			tipc_link_proto_xmit(l_ptr, STATE_MSG, 0, 0, 0, 0, 0);
 	} else {
 		l_ptr->stats.duplicates++;
@@ -1375,11 +1357,11 @@ void tipc_link_proto_xmit(struct tipc_link *l_ptr, u32 msg_typ, int probe_msg,
 
 		if (!tipc_link_is_up(l_ptr))
 			return;
-		if (l_ptr->next_out)
-			next_sent = buf_seqno(l_ptr->next_out);
+		if (skb_queue_len(&l_ptr->backlogq))
+			next_sent = buf_seqno(skb_peek(&l_ptr->backlogq));
 		msg_set_next_sent(msg, next_sent);
-		if (!skb_queue_empty(&l_ptr->deferred_queue)) {
-			u32 rec = buf_seqno(skb_peek(&l_ptr->deferred_queue));
+		if (!skb_queue_empty(&l_ptr->deferdq)) {
+			u32 rec = buf_seqno(skb_peek(&l_ptr->deferdq));
 			gap = mod(rec - mod(l_ptr->next_in_no));
 		}
 		msg_set_seq_gap(msg, gap);
@@ -1431,10 +1413,9 @@ void tipc_link_proto_xmit(struct tipc_link *l_ptr, u32 msg_typ, int probe_msg,
 
 	skb_copy_to_linear_data(buf, msg, sizeof(l_ptr->proto_msg));
 	buf->priority = TC_PRIO_CONTROL;
-
 	tipc_bearer_send(l_ptr->owner->net, l_ptr->bearer_id, buf,
 			 &l_ptr->media_addr);
-	l_ptr->unacked_window = 0;
+	l_ptr->rcv_unacked = 0;
 	kfree_skb(buf);
 }
 
@@ -1569,7 +1550,7 @@ static void tipc_link_proto_rcv(struct tipc_link *l_ptr,
 		}
 		if (msg_seq_gap(msg)) {
 			l_ptr->stats.recv_nacks++;
-			tipc_link_retransmit(l_ptr, skb_peek(&l_ptr->outqueue),
+			tipc_link_retransmit(l_ptr, skb_peek(&l_ptr->transmq),
 					     msg_seq_gap(msg));
 		}
 		break;
@@ -1616,7 +1597,7 @@ static void tipc_link_tunnel_xmit(struct tipc_link *l_ptr,
  */
 void tipc_link_failover_send_queue(struct tipc_link *l_ptr)
 {
-	u32 msgcount = skb_queue_len(&l_ptr->outqueue);
+	int msgcount;
 	struct tipc_link *tunnel = l_ptr->owner->active_links[0];
 	struct tipc_msg tunnel_hdr;
 	struct sk_buff *skb;
@@ -1627,10 +1608,12 @@ void tipc_link_failover_send_queue(struct tipc_link *l_ptr)
 
 	tipc_msg_init(link_own_addr(l_ptr), &tunnel_hdr, CHANGEOVER_PROTOCOL,
 		      ORIGINAL_MSG, INT_H_SIZE, l_ptr->addr);
+	skb_queue_splice_tail_init(&l_ptr->backlogq, &l_ptr->transmq);
+	msgcount = skb_queue_len(&l_ptr->transmq);
 	msg_set_bearer_id(&tunnel_hdr, l_ptr->peer_bearer_id);
 	msg_set_msgcnt(&tunnel_hdr, msgcount);
 
-	if (skb_queue_empty(&l_ptr->outqueue)) {
+	if (skb_queue_empty(&l_ptr->transmq)) {
 		skb = tipc_buf_acquire(INT_H_SIZE);
 		if (skb) {
 			skb_copy_to_linear_data(skb, &tunnel_hdr, INT_H_SIZE);
@@ -1646,7 +1629,7 @@ void tipc_link_failover_send_queue(struct tipc_link *l_ptr)
 	split_bundles = (l_ptr->owner->active_links[0] !=
 			 l_ptr->owner->active_links[1]);
 
-	skb_queue_walk(&l_ptr->outqueue, skb) {
+	skb_queue_walk(&l_ptr->transmq, skb) {
 		struct tipc_msg *msg = buf_msg(skb);
 
 		if ((msg_user(msg) == MSG_BUNDLER) && split_bundles) {
@@ -1677,39 +1660,46 @@ void tipc_link_failover_send_queue(struct tipc_link *l_ptr)
  * and sequence order is preserved per sender/receiver socket pair.
  * Owner node is locked.
  */
-void tipc_link_dup_queue_xmit(struct tipc_link *l_ptr,
-			      struct tipc_link *tunnel)
+void tipc_link_dup_queue_xmit(struct tipc_link *link,
+			      struct tipc_link *tnl)
 {
 	struct sk_buff *skb;
-	struct tipc_msg tunnel_hdr;
-
-	tipc_msg_init(link_own_addr(l_ptr), &tunnel_hdr, CHANGEOVER_PROTOCOL,
-		      DUPLICATE_MSG, INT_H_SIZE, l_ptr->addr);
-	msg_set_msgcnt(&tunnel_hdr, skb_queue_len(&l_ptr->outqueue));
-	msg_set_bearer_id(&tunnel_hdr, l_ptr->peer_bearer_id);
-	skb_queue_walk(&l_ptr->outqueue, skb) {
+	struct tipc_msg tnl_hdr;
+	struct sk_buff_head *queue = &link->transmq;
+	int mcnt;
+
+	tipc_msg_init(link_own_addr(link), &tnl_hdr, CHANGEOVER_PROTOCOL,
+		      DUPLICATE_MSG, INT_H_SIZE, link->addr);
+	mcnt = skb_queue_len(&link->transmq) + skb_queue_len(&link->backlogq);
+	msg_set_msgcnt(&tnl_hdr, mcnt);
+	msg_set_bearer_id(&tnl_hdr, link->peer_bearer_id);
+
+tunnel_queue:
+	skb_queue_walk(queue, skb) {
 		struct sk_buff *outskb;
 		struct tipc_msg *msg = buf_msg(skb);
-		u32 length = msg_size(msg);
+		u32 len = msg_size(msg);
 
-		if (msg_user(msg) == MSG_BUNDLER)
-			msg_set_type(msg, CLOSED_MSG);
-		msg_set_ack(msg, mod(l_ptr->next_in_no - 1));	/* Update */
-		msg_set_bcast_ack(msg, l_ptr->owner->bclink.last_in);
-		msg_set_size(&tunnel_hdr, length + INT_H_SIZE);
-		outskb = tipc_buf_acquire(length + INT_H_SIZE);
+		msg_set_ack(msg, mod(link->next_in_no - 1));
+		msg_set_bcast_ack(msg, link->owner->bclink.last_in);
+		msg_set_size(&tnl_hdr, len + INT_H_SIZE);
+		outskb = tipc_buf_acquire(len + INT_H_SIZE);
 		if (outskb == NULL) {
 			pr_warn("%sunable to send duplicate msg\n",
 				link_co_err);
 			return;
 		}
-		skb_copy_to_linear_data(outskb, &tunnel_hdr, INT_H_SIZE);
-		skb_copy_to_linear_data_offset(outskb, INT_H_SIZE, skb->data,
-					       length);
-		__tipc_link_xmit_skb(tunnel, outskb);
-		if (!tipc_link_is_up(l_ptr))
+		skb_copy_to_linear_data(outskb, &tnl_hdr, INT_H_SIZE);
+		skb_copy_to_linear_data_offset(outskb, INT_H_SIZE,
+					       skb->data, len);
+		__tipc_link_xmit_skb(tnl, outskb);
+		if (!tipc_link_is_up(link))
 			return;
 	}
+	if (queue == &link->backlogq)
+		return;
+	queue = &link->backlogq;
+	goto tunnel_queue;
 }
 
 /* tipc_link_dup_rcv(): Receive a tunnelled DUPLICATE_MSG packet.
@@ -1823,6 +1813,8 @@ static void link_set_supervision_props(struct tipc_link *l_ptr, u32 tol)
 
 void tipc_link_set_queue_limits(struct tipc_link *l_ptr, u32 window)
 {
+	l_ptr->window = window;
+
 	/* Data messages from this node, inclusive FIRST_FRAGM */
 	l_ptr->queue_limit[TIPC_LOW_IMPORTANCE] = window;
 	l_ptr->queue_limit[TIPC_MEDIUM_IMPORTANCE] = (window / 3) * 4;
diff --git a/net/tipc/link.h b/net/tipc/link.h
index 7aeb52092bf3..eec3ecf2d450 100644
--- a/net/tipc/link.h
+++ b/net/tipc/link.h
@@ -124,7 +124,8 @@ struct tipc_stats {
  * @max_pkt: current maximum packet size for this link
  * @max_pkt_target: desired maximum packet size for this link
  * @max_pkt_probes: # of probes based on current (max_pkt, max_pkt_target)
- * @outqueue: outbound message queue
+ * @transmitq: queue for sent, non-acked messages
+ * @backlogq: queue for messages waiting to be sent
  * @next_out_no: next sequence number to use for outbound messages
  * @last_retransmitted: sequence number of most recently retransmitted message
  * @stale_count: # of identical retransmit requests made by peer
@@ -177,20 +178,21 @@ struct tipc_link {
 	u32 max_pkt_probes;
 
 	/* Sending */
-	struct sk_buff_head outqueue;
+	struct sk_buff_head transmq;
+	struct sk_buff_head backlogq;
 	u32 next_out_no;
+	u32 window;
 	u32 last_retransmitted;
 	u32 stale_count;
 
 	/* Reception */
 	u32 next_in_no;
-	struct sk_buff_head deferred_queue;
-	u32 unacked_window;
+	u32 rcv_unacked;
+	struct sk_buff_head deferdq;
 	struct sk_buff_head inputq;
 	struct sk_buff_head namedq;
 
 	/* Congestion handling */
-	struct sk_buff *next_out;
 	struct sk_buff_head wakeupq;
 
 	/* Fragmentation/reassembly */
@@ -302,9 +304,4 @@ static inline int link_reset_reset(struct tipc_link *l_ptr)
 	return l_ptr->state == RESET_RESET;
 }
 
-static inline int link_congested(struct tipc_link *l_ptr)
-{
-	return skb_queue_len(&l_ptr->outqueue) >= l_ptr->queue_limit[0];
-}
-
 #endif
diff --git a/net/tipc/msg.c b/net/tipc/msg.c
index 333d2ae1cf76..47c8fd8e2fb2 100644
--- a/net/tipc/msg.c
+++ b/net/tipc/msg.c
@@ -330,33 +330,36 @@ error:
 
 /**
  * tipc_msg_bundle(): Append contents of a buffer to tail of an existing one
- * @list: the buffer chain of the existing buffer ("bundle")
+ * @bskb: the buffer to append to ("bundle")
  * @skb:  buffer to be appended
  * @mtu:  max allowable size for the bundle buffer
  * Consumes buffer if successful
  * Returns true if bundling could be performed, otherwise false
  */
-bool tipc_msg_bundle(struct sk_buff_head *list, struct sk_buff *skb, u32 mtu)
+bool tipc_msg_bundle(struct sk_buff *bskb, struct sk_buff *skb, u32 mtu)
 {
-	struct sk_buff *bskb = skb_peek_tail(list);
-	struct tipc_msg *bmsg = buf_msg(bskb);
+	struct tipc_msg *bmsg;
 	struct tipc_msg *msg = buf_msg(skb);
-	unsigned int bsz = msg_size(bmsg);
+	unsigned int bsz;
 	unsigned int msz = msg_size(msg);
-	u32 start = align(bsz);
+	u32 start, pad;
 	u32 max = mtu - INT_H_SIZE;
-	u32 pad = start - bsz;
 
 	if (likely(msg_user(msg) == MSG_FRAGMENTER))
 		return false;
+	if (!bskb)
+		return false;
+	bmsg = buf_msg(bskb);
+	bsz = msg_size(bmsg);
+	start = align(bsz);
+	pad = start - bsz;
+
 	if (unlikely(msg_user(msg) == CHANGEOVER_PROTOCOL))
 		return false;
 	if (unlikely(msg_user(msg) == BCAST_PROTOCOL))
 		return false;
 	if (likely(msg_user(bmsg) != MSG_BUNDLER))
 		return false;
-	if (likely(!TIPC_SKB_CB(bskb)->bundling))
-		return false;
 	if (unlikely(skb_tailroom(bskb) < (pad + msz)))
 		return false;
 	if (unlikely(max < (start + msz)))
@@ -419,12 +422,11 @@ none:
  * Replaces buffer if successful
  * Returns true if success, otherwise false
  */
-bool tipc_msg_make_bundle(struct sk_buff_head *list,
-			  struct sk_buff *skb, u32 mtu, u32 dnode)
+bool tipc_msg_make_bundle(struct sk_buff **skb, u32 mtu, u32 dnode)
 {
 	struct sk_buff *bskb;
 	struct tipc_msg *bmsg;
-	struct tipc_msg *msg = buf_msg(skb);
+	struct tipc_msg *msg = buf_msg(*skb);
 	u32 msz = msg_size(msg);
 	u32 max = mtu - INT_H_SIZE;
 
@@ -448,9 +450,9 @@ bool tipc_msg_make_bundle(struct sk_buff_head *list,
 	msg_set_seqno(bmsg, msg_seqno(msg));
 	msg_set_ack(bmsg, msg_ack(msg));
 	msg_set_bcast_ack(bmsg, msg_bcast_ack(msg));
-	TIPC_SKB_CB(bskb)->bundling = true;
-	__skb_queue_tail(list, bskb);
-	return tipc_msg_bundle(list, skb, mtu);
+	tipc_msg_bundle(bskb, *skb, mtu);
+	*skb = bskb;
+	return true;
 }
 
 /**
diff --git a/net/tipc/msg.h b/net/tipc/msg.h
index 62306b8d2410..e5fc5fdb2ea7 100644
--- a/net/tipc/msg.h
+++ b/net/tipc/msg.h
@@ -767,9 +767,9 @@ struct sk_buff *tipc_msg_create(uint user, uint type, uint hdr_sz,
 				uint data_sz, u32 dnode, u32 onode,
 				u32 dport, u32 oport, int errcode);
 int tipc_buf_append(struct sk_buff **headbuf, struct sk_buff **buf);
-bool tipc_msg_bundle(struct sk_buff_head *list, struct sk_buff *skb, u32 mtu);
-bool tipc_msg_make_bundle(struct sk_buff_head *list,
-			  struct sk_buff *skb, u32 mtu, u32 dnode);
+bool tipc_msg_bundle(struct sk_buff *bskb, struct sk_buff *skb, u32 mtu);
+
+bool tipc_msg_make_bundle(struct sk_buff **skb, u32 mtu, u32 dnode);
 bool tipc_msg_extract(struct sk_buff *skb, struct sk_buff **iskb, int *pos);
 int tipc_msg_build(struct tipc_msg *mhdr, struct msghdr *m,
 		   int offset, int dsz, int mtu, struct sk_buff_head *list);
diff --git a/net/tipc/node.c b/net/tipc/node.c
index 86152de8248d..26d1de1bf34d 100644
--- a/net/tipc/node.c
+++ b/net/tipc/node.c
@@ -111,7 +111,7 @@ struct tipc_node *tipc_node_create(struct net *net, u32 addr)
 	INIT_LIST_HEAD(&n_ptr->list);
 	INIT_LIST_HEAD(&n_ptr->publ_list);
 	INIT_LIST_HEAD(&n_ptr->conn_sks);
-	__skb_queue_head_init(&n_ptr->bclink.deferred_queue);
+	__skb_queue_head_init(&n_ptr->bclink.deferdq);
 	hlist_add_head_rcu(&n_ptr->hash, &tn->node_htable[tipc_hashfn(addr)]);
 	list_for_each_entry_rcu(temp_node, &tn->node_list, list) {
 		if (n_ptr->addr < temp_node->addr)
@@ -354,7 +354,7 @@ static void node_lost_contact(struct tipc_node *n_ptr)
 
 	/* Flush broadcast link info associated with lost node */
 	if (n_ptr->bclink.recv_permitted) {
-		__skb_queue_purge(&n_ptr->bclink.deferred_queue);
+		__skb_queue_purge(&n_ptr->bclink.deferdq);
 
 		if (n_ptr->bclink.reasm_buf) {
 			kfree_skb(n_ptr->bclink.reasm_buf);
diff --git a/net/tipc/node.h b/net/tipc/node.h
index f78be64e105b..e89ac04ec2c3 100644
--- a/net/tipc/node.h
+++ b/net/tipc/node.h
@@ -84,7 +84,7 @@ struct tipc_node_bclink {
 	u32 last_sent;
 	u32 oos_state;
 	u32 deferred_size;
-	struct sk_buff_head deferred_queue;
+	struct sk_buff_head deferdq;
 	struct sk_buff *reasm_buf;
 	int inputq_map;
 	bool recv_permitted;