Merge branch 'tipc-next'

Ying Xue says:

====================
standardize TIPC SKB queue operations

Now the following SKB queues are created and maintained within internal
TIPC stack:

- link transmission queue
- link deferred queue
- link receive queue
- socket outgoing packet chain
- name table outgoing packet chain

In order to manage above queues, TIPC stack declares a sk_buff pointer
for each queue to record its head, and directly modifies "prev" and
"next" SKB pointers of SKB structure when inserting or deleting a SKB
to or from the queue. As these operations are pretty complex, they
easily involve fatal mistakes. If these sk_buff pointers are replaced
with sk_buff_head instances as queue heads and corresponding generic
SKB list APIs are used to manage them, the entire TIPC code would
become quite clean and readable. But before make the change, we need
to clean up below redundant functionalities:

- remove node subscribe infrastructure
- remove protocol message queue
- remove retransmission queue
- clean up process of pushing packets in link layer
====================

Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 213 insertions, 301 deletions

diff --git a/net/tipc/link.c b/net/tipc/link.c
index 4738cb1bf7c..34bf15c90c7 100644
--- a/net/tipc/link.c
+++ b/net/tipc/link.c
@@ -149,18 +149,6 @@ static void link_init_max_pkt(struct tipc_link *l_ptr)
 	l_ptr->max_pkt_probes = 0;
 }
 
-static u32 link_next_sent(struct tipc_link *l_ptr)
-{
-	if (l_ptr->next_out)
-		return buf_seqno(l_ptr->next_out);
-	return mod(l_ptr->next_out_no);
-}
-
-static u32 link_last_sent(struct tipc_link *l_ptr)
-{
-	return mod(link_next_sent(l_ptr) - 1);
-}
-
 /*
  *  Simple non-static link routines (i.e. referenced outside this file)
  */
@@ -183,14 +171,17 @@ int tipc_link_is_active(struct tipc_link *l_ptr)
  */
 static void link_timeout(struct tipc_link *l_ptr)
 {
+	struct sk_buff *skb;
+
 	tipc_node_lock(l_ptr->owner);
 
 	/* update counters used in statistical profiling of send traffic */
-	l_ptr->stats.accu_queue_sz += l_ptr->out_queue_size;
+	l_ptr->stats.accu_queue_sz += skb_queue_len(&l_ptr->outqueue);
 	l_ptr->stats.queue_sz_counts++;
 
-	if (l_ptr->first_out) {
-		struct tipc_msg *msg = buf_msg(l_ptr->first_out);
+	skb = skb_peek(&l_ptr->outqueue);
+	if (skb) {
+		struct tipc_msg *msg = buf_msg(skb);
 		u32 length = msg_size(msg);
 
 		if ((msg_user(msg) == MSG_FRAGMENTER) &&
@@ -218,11 +209,10 @@ static void link_timeout(struct tipc_link *l_ptr)
 	}
 
 	/* do all other link processing performed on a periodic basis */
-
 	link_state_event(l_ptr, TIMEOUT_EVT);
 
 	if (l_ptr->next_out)
-		tipc_link_push_queue(l_ptr);
+		tipc_link_push_packets(l_ptr);
 
 	tipc_node_unlock(l_ptr->owner);
 }
@@ -301,6 +291,8 @@ 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->waiting_sks);
 
 	link_reset_statistics(l_ptr);
@@ -379,30 +371,19 @@ static bool link_schedule_user(struct tipc_link *link, u32 oport,
  */
 static void link_prepare_wakeup(struct tipc_link *link)
 {
-	struct sk_buff_head *wq = &link->waiting_sks;
-	struct sk_buff *buf;
-	uint pend_qsz = link->out_queue_size;
+	uint pend_qsz = skb_queue_len(&link->outqueue);
+	struct sk_buff *skb, *tmp;
 
-	for (buf = skb_peek(wq); buf; buf = skb_peek(wq)) {
-		if (pend_qsz >= link->queue_limit[TIPC_SKB_CB(buf)->chain_imp])
+	skb_queue_walk_safe(&link->waiting_sks, skb, tmp) {
+		if (pend_qsz >= link->queue_limit[TIPC_SKB_CB(skb)->chain_imp])
 			break;
-		pend_qsz += TIPC_SKB_CB(buf)->chain_sz;
-		__skb_queue_tail(&link->owner->waiting_sks, __skb_dequeue(wq));
+		pend_qsz += TIPC_SKB_CB(skb)->chain_sz;
+		__skb_unlink(skb, &link->waiting_sks);
+		__skb_queue_tail(&link->owner->waiting_sks, skb);
 	}
 }
 
 /**
- * link_release_outqueue - purge link's outbound message queue
- * @l_ptr: pointer to link
- */
-static void link_release_outqueue(struct tipc_link *l_ptr)
-{
-	kfree_skb_list(l_ptr->first_out);
-	l_ptr->first_out = NULL;
-	l_ptr->out_queue_size = 0;
-}
-
-/**
  * tipc_link_reset_fragments - purge link's inbound message fragments queue
  * @l_ptr: pointer to link
  */
@@ -418,11 +399,9 @@ void tipc_link_reset_fragments(struct tipc_link *l_ptr)
  */
 void tipc_link_purge_queues(struct tipc_link *l_ptr)
 {
-	kfree_skb_list(l_ptr->oldest_deferred_in);
-	kfree_skb_list(l_ptr->first_out);
+	__skb_queue_purge(&l_ptr->deferred_queue);
+	__skb_queue_purge(&l_ptr->outqueue);
 	tipc_link_reset_fragments(l_ptr);
-	kfree_skb(l_ptr->proto_msg_queue);
-	l_ptr->proto_msg_queue = NULL;
 }
 
 void tipc_link_reset(struct tipc_link *l_ptr)
@@ -454,25 +433,16 @@ void tipc_link_reset(struct tipc_link *l_ptr)
 	}
 
 	/* Clean up all queues: */
-	link_release_outqueue(l_ptr);
-	kfree_skb(l_ptr->proto_msg_queue);
-	l_ptr->proto_msg_queue = NULL;
-	kfree_skb_list(l_ptr->oldest_deferred_in);
+	__skb_queue_purge(&l_ptr->outqueue);
+	__skb_queue_purge(&l_ptr->deferred_queue);
 	if (!skb_queue_empty(&l_ptr->waiting_sks)) {
 		skb_queue_splice_init(&l_ptr->waiting_sks, &owner->waiting_sks);
 		owner->action_flags |= TIPC_WAKEUP_USERS;
 	}
-	l_ptr->retransm_queue_head = 0;
-	l_ptr->retransm_queue_size = 0;
-	l_ptr->last_out = NULL;
-	l_ptr->first_out = NULL;
 	l_ptr->next_out = NULL;
 	l_ptr->unacked_window = 0;
 	l_ptr->checkpoint = 1;
 	l_ptr->next_out_no = 1;
-	l_ptr->deferred_inqueue_sz = 0;
-	l_ptr->oldest_deferred_in = NULL;
-	l_ptr->newest_deferred_in = NULL;
 	l_ptr->fsm_msg_cnt = 0;
 	l_ptr->stale_count = 0;
 	link_reset_statistics(l_ptr);
@@ -694,9 +664,10 @@ static void link_state_event(struct tipc_link *l_ptr, unsigned int event)
  * - For all other messages we discard the buffer and return -EHOSTUNREACH
  * - For TIPC internal messages we also reset the link
  */
-static int tipc_link_cong(struct tipc_link *link, struct sk_buff *buf)
+static int tipc_link_cong(struct tipc_link *link, struct sk_buff_head *list)
 {
-	struct tipc_msg *msg = buf_msg(buf);
+	struct sk_buff *skb = skb_peek(list);
+	struct tipc_msg *msg = buf_msg(skb);
 	uint imp = tipc_msg_tot_importance(msg);
 	u32 oport = msg_tot_origport(msg);
 
@@ -709,30 +680,30 @@ static int tipc_link_cong(struct tipc_link *link, struct sk_buff *buf)
 		goto drop;
 	if (unlikely(msg_reroute_cnt(msg)))
 		goto drop;
-	if (TIPC_SKB_CB(buf)->wakeup_pending)
+	if (TIPC_SKB_CB(skb)->wakeup_pending)
 		return -ELINKCONG;
-	if (link_schedule_user(link, oport, TIPC_SKB_CB(buf)->chain_sz, imp))
+	if (link_schedule_user(link, oport, skb_queue_len(list), imp))
 		return -ELINKCONG;
 drop:
-	kfree_skb_list(buf);
+	__skb_queue_purge(list);
 	return -EHOSTUNREACH;
 }
 
 /**
  * __tipc_link_xmit(): same as tipc_link_xmit, but destlink is known & locked
  * @link: link to use
- * @buf: chain of buffers containing message
+ * @list: chain of buffers containing message
+ *
  * Consumes the buffer chain, except when returning -ELINKCONG
  * Returns 0 if success, otherwise errno: -ELINKCONG, -EMSGSIZE (plain socket
  * user data messages) or -EHOSTUNREACH (all other messages/senders)
  * Only the socket functions tipc_send_stream() and tipc_send_packet() need
  * to act on the return value, since they may need to do more send attempts.
  */
-int __tipc_link_xmit(struct tipc_link *link, struct sk_buff *buf)
+int __tipc_link_xmit(struct tipc_link *link, struct sk_buff_head *list)
 {
-	struct tipc_msg *msg = buf_msg(buf);
+	struct tipc_msg *msg = buf_msg(skb_peek(list));
 	uint psz = msg_size(msg);
-	uint qsz = link->out_queue_size;
 	uint sndlim = link->queue_limit[0];
 	uint imp = tipc_msg_tot_importance(msg);
 	uint mtu = link->max_pkt;
@@ -740,71 +711,83 @@ int __tipc_link_xmit(struct tipc_link *link, struct sk_buff *buf)
 	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 *next = buf->next;
+	struct sk_buff_head *outqueue = &link->outqueue;
+	struct sk_buff *skb, *tmp;
 
 	/* Match queue limits against msg importance: */
-	if (unlikely(qsz >= link->queue_limit[imp]))
-		return tipc_link_cong(link, buf);
+	if (unlikely(skb_queue_len(outqueue) >= link->queue_limit[imp]))
+		return tipc_link_cong(link, list);
 
 	/* Has valid packet limit been used ? */
 	if (unlikely(psz > mtu)) {
-		kfree_skb_list(buf);
+		__skb_queue_purge(list);
 		return -EMSGSIZE;
 	}
 
 	/* Prepare each packet for sending, and add to outqueue: */
-	while (buf) {
-		next = buf->next;
-		msg = buf_msg(buf);
+	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_bcast_ack(msg, bc_last_in);
 
-		if (!link->first_out) {
-			link->first_out = buf;
-		} else if (qsz < sndlim) {
-			link->last_out->next = buf;
-		} else if (tipc_msg_bundle(link->last_out, buf, mtu)) {
+		if (skb_queue_len(outqueue) < sndlim) {
+			__skb_queue_tail(outqueue, skb);
+			tipc_bearer_send(link->bearer_id, skb, addr);
+			link->next_out = NULL;
+			link->unacked_window = 0;
+		} else if (tipc_msg_bundle(outqueue, skb, mtu)) {
 			link->stats.sent_bundled++;
-			buf = next;
-			next = buf->next;
 			continue;
-		} else if (tipc_msg_make_bundle(&buf, mtu, link->addr)) {
+		} else if (tipc_msg_make_bundle(outqueue, skb, mtu,
+						link->addr)) {
 			link->stats.sent_bundled++;
 			link->stats.sent_bundles++;
-			link->last_out->next = buf;
 			if (!link->next_out)
-				link->next_out = buf;
+				link->next_out = skb_peek_tail(outqueue);
 		} else {
-			link->last_out->next = buf;
+			__skb_queue_tail(outqueue, skb);
 			if (!link->next_out)
-				link->next_out = buf;
-		}
-
-		/* Send packet if possible: */
-		if (likely(++qsz <= sndlim)) {
-			tipc_bearer_send(link->bearer_id, buf, addr);
-			link->next_out = next;
-			link->unacked_window = 0;
+				link->next_out = skb;
 		}
 		seqno++;
-		link->last_out = buf;
-		buf = next;
 	}
 	link->next_out_no = seqno;
-	link->out_queue_size = qsz;
 	return 0;
 }
 
+static void skb2list(struct sk_buff *skb, struct sk_buff_head *list)
+{
+	__skb_queue_head_init(list);
+	__skb_queue_tail(list, skb);
+}
+
+static int __tipc_link_xmit_skb(struct tipc_link *link, struct sk_buff *skb)
+{
+	struct sk_buff_head head;
+
+	skb2list(skb, &head);
+	return __tipc_link_xmit(link, &head);
+}
+
+int tipc_link_xmit_skb(struct sk_buff *skb, u32 dnode, u32 selector)
+{
+	struct sk_buff_head head;
+
+	skb2list(skb, &head);
+	return tipc_link_xmit(&head, dnode, selector);
+}
+
 /**
  * tipc_link_xmit() is the general link level function for message sending
- * @buf: chain of buffers containing message
+ * @list: chain of buffers containing message
  * @dsz: amount of user data to be sent
  * @dnode: address of destination node
  * @selector: a number used for deterministic link selection
  * Consumes the buffer chain, except when returning -ELINKCONG
  * Returns 0 if success, otherwise errno: -ELINKCONG,-EHOSTUNREACH,-EMSGSIZE
  */
-int tipc_link_xmit(struct sk_buff *buf, u32 dnode, u32 selector)
+int tipc_link_xmit(struct sk_buff_head *list, u32 dnode, u32 selector)
 {
 	struct tipc_link *link = NULL;
 	struct tipc_node *node;
@@ -815,17 +798,22 @@ int tipc_link_xmit(struct sk_buff *buf, u32 dnode, u32 selector)
 		tipc_node_lock(node);
 		link = node->active_links[selector & 1];
 		if (link)
-			rc = __tipc_link_xmit(link, buf);
+			rc = __tipc_link_xmit(link, list);
 		tipc_node_unlock(node);
 	}
 
 	if (link)
 		return rc;
 
-	if (likely(in_own_node(dnode)))
-		return tipc_sk_rcv(buf);
+	if (likely(in_own_node(dnode))) {
+		/* As a node local message chain never contains more than one
+		 * buffer, we just need to dequeue one SKB buffer from the
+		 * head list.
+		 */
+		return tipc_sk_rcv(__skb_dequeue(list));
+	}
+	__skb_queue_purge(list);
 
-	kfree_skb_list(buf);
 	return rc;
 }
 
@@ -839,17 +827,17 @@ int tipc_link_xmit(struct sk_buff *buf, u32 dnode, u32 selector)
  */
 static void tipc_link_sync_xmit(struct tipc_link *link)
 {
-	struct sk_buff *buf;
+	struct sk_buff *skb;
 	struct tipc_msg *msg;
 
-	buf = tipc_buf_acquire(INT_H_SIZE);
-	if (!buf)
+	skb = tipc_buf_acquire(INT_H_SIZE);
+	if (!skb)
 		return;
 
-	msg = buf_msg(buf);
+	msg = buf_msg(skb);
 	tipc_msg_init(msg, BCAST_PROTOCOL, STATE_MSG, INT_H_SIZE, link->addr);
 	msg_set_last_bcast(msg, link->owner->bclink.acked);
-	__tipc_link_xmit(link, buf);
+	__tipc_link_xmit_skb(link, skb);
 }
 
 /*
@@ -869,85 +857,46 @@ 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_packet: Push one unsent packet to the media
+ * tipc_link_push_packets - push unsent packets to bearer
+ *
+ * Push out the unsent messages of a link where congestion
+ * has abated. Node is locked.
+ *
+ * Called with node locked
  */
-static u32 tipc_link_push_packet(struct tipc_link *l_ptr)
-{
-	struct sk_buff *buf = l_ptr->first_out;
-	u32 r_q_size = l_ptr->retransm_queue_size;
-	u32 r_q_head = l_ptr->retransm_queue_head;
-
-	/* Step to position where retransmission failed, if any,    */
-	/* consider that buffers may have been released in meantime */
-	if (r_q_size && buf) {
-		u32 last = lesser(mod(r_q_head + r_q_size),
-				  link_last_sent(l_ptr));
-		u32 first = buf_seqno(buf);
-
-		while (buf && less(first, r_q_head)) {
-			first = mod(first + 1);
-			buf = buf->next;
-		}
-		l_ptr->retransm_queue_head = r_q_head = first;
-		l_ptr->retransm_queue_size = r_q_size = mod(last - first);
-	}
-
-	/* Continue retransmission now, if there is anything: */
-	if (r_q_size && buf) {
-		msg_set_ack(buf_msg(buf), mod(l_ptr->next_in_no - 1));
-		msg_set_bcast_ack(buf_msg(buf), l_ptr->owner->bclink.last_in);
-		tipc_bearer_send(l_ptr->bearer_id, buf, &l_ptr->media_addr);
-		l_ptr->retransm_queue_head = mod(++r_q_head);
-		l_ptr->retransm_queue_size = --r_q_size;
-		l_ptr->stats.retransmitted++;
-		return 0;
-	}
-
-	/* Send deferred protocol message, if any: */
-	buf = l_ptr->proto_msg_queue;
-	if (buf) {
-		msg_set_ack(buf_msg(buf), mod(l_ptr->next_in_no - 1));
-		msg_set_bcast_ack(buf_msg(buf), l_ptr->owner->bclink.last_in);
-		tipc_bearer_send(l_ptr->bearer_id, buf, &l_ptr->media_addr);
-		l_ptr->unacked_window = 0;
-		kfree_skb(buf);
-		l_ptr->proto_msg_queue = NULL;
-		return 0;
-	}
+void tipc_link_push_packets(struct tipc_link *l_ptr)
+{
+	struct sk_buff_head *outqueue = &l_ptr->outqueue;
+	struct sk_buff *skb = l_ptr->next_out;
+	struct tipc_msg *msg;
+	u32 next, first;
 
-	/* Send one deferred data message, if send window not full: */
-	buf = l_ptr->next_out;
-	if (buf) {
-		struct tipc_msg *msg = buf_msg(buf);
-		u32 next = msg_seqno(msg);
-		u32 first = buf_seqno(l_ptr->first_out);
+	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);
-			tipc_bearer_send(l_ptr->bearer_id, buf,
-					 &l_ptr->media_addr);
 			if (msg_user(msg) == MSG_BUNDLER)
-				msg_set_type(msg, BUNDLE_CLOSED);
-			l_ptr->next_out = buf->next;
-			return 0;
+				TIPC_SKB_CB(skb)->bundling = false;
+			tipc_bearer_send(l_ptr->bearer_id, skb,
+					 &l_ptr->media_addr);
+			l_ptr->next_out = tipc_skb_queue_next(outqueue, skb);
+		} else {
+			break;
 		}
 	}
-	return 1;
-}
-
-/*
- * push_queue(): push out the unsent messages of a link where
- *               congestion has abated. Node is locked
- */
-void tipc_link_push_queue(struct tipc_link *l_ptr)
-{
-	u32 res;
-
-	do {
-		res = tipc_link_push_packet(l_ptr);
-	} while (!res);
 }
 
 void tipc_link_reset_all(struct tipc_node *node)
@@ -1011,20 +960,20 @@ static void link_retransmit_failure(struct tipc_link *l_ptr,
 	}
 }
 
-void tipc_link_retransmit(struct tipc_link *l_ptr, struct sk_buff *buf,
+void tipc_link_retransmit(struct tipc_link *l_ptr, struct sk_buff *skb,
 			  u32 retransmits)
 {
 	struct tipc_msg *msg;
 
-	if (!buf)
+	if (!skb)
 		return;
 
-	msg = buf_msg(buf);
+	msg = buf_msg(skb);
 
 	/* Detect repeated retransmit failures */
 	if (l_ptr->last_retransmitted == msg_seqno(msg)) {
 		if (++l_ptr->stale_count > 100) {
-			link_retransmit_failure(l_ptr, buf);
+			link_retransmit_failure(l_ptr, skb);
 			return;
 		}
 	} else {
@@ -1032,38 +981,29 @@ void tipc_link_retransmit(struct tipc_link *l_ptr, struct sk_buff *buf,
 		l_ptr->stale_count = 1;
 	}
 
-	while (retransmits && (buf != l_ptr->next_out) && buf) {
-		msg = buf_msg(buf);
+	skb_queue_walk_from(&l_ptr->outqueue, skb) {
+		if (!retransmits || skb == l_ptr->next_out)
+			break;
+		msg = buf_msg(skb);
 		msg_set_ack(msg, mod(l_ptr->next_in_no - 1));
 		msg_set_bcast_ack(msg, l_ptr->owner->bclink.last_in);
-		tipc_bearer_send(l_ptr->bearer_id, buf, &l_ptr->media_addr);
-		buf = buf->next;
+		tipc_bearer_send(l_ptr->bearer_id, skb, &l_ptr->media_addr);
 		retransmits--;
 		l_ptr->stats.retransmitted++;
 	}
-
-	l_ptr->retransm_queue_head = l_ptr->retransm_queue_size = 0;
 }
 
-/**
- * link_insert_deferred_queue - insert deferred messages back into receive chain
- */
-static struct sk_buff *link_insert_deferred_queue(struct tipc_link *l_ptr,
-						  struct sk_buff *buf)
+static void link_retrieve_defq(struct tipc_link *link,
+			       struct sk_buff_head *list)
 {
 	u32 seq_no;
 
-	if (l_ptr->oldest_deferred_in == NULL)
-		return buf;
+	if (skb_queue_empty(&link->deferred_queue))
+		return;
 
-	seq_no = buf_seqno(l_ptr->oldest_deferred_in);
-	if (seq_no == mod(l_ptr->next_in_no)) {
-		l_ptr->newest_deferred_in->next = buf;
-		buf = l_ptr->oldest_deferred_in;
-		l_ptr->oldest_deferred_in = NULL;
-		l_ptr->deferred_inqueue_sz = 0;
-	}
-	return buf;
+	seq_no = buf_seqno(skb_peek(&link->deferred_queue));
+	if (seq_no == mod(link->next_in_no))
+		skb_queue_splice_tail_init(&link->deferred_queue, list);
 }
 
 /**
@@ -1123,43 +1063,42 @@ static int link_recv_buf_validate(struct sk_buff *buf)
 
 /**
  * tipc_rcv - process TIPC packets/messages arriving from off-node
- * @head: pointer to message buffer chain
+ * @skb: TIPC packet
  * @b_ptr: pointer to bearer message arrived on
  *
  * Invoked with no locks held.  Bearer pointer must point to a valid bearer
  * structure (i.e. cannot be NULL), but bearer can be inactive.
  */
-void tipc_rcv(struct sk_buff *head, struct tipc_bearer *b_ptr)
+void tipc_rcv(struct sk_buff *skb, struct tipc_bearer *b_ptr)
 {
-	while (head) {
-		struct tipc_node *n_ptr;
-		struct tipc_link *l_ptr;
-		struct sk_buff *crs;
-		struct sk_buff *buf = head;
-		struct tipc_msg *msg;
-		u32 seq_no;
-		u32 ackd;
-		u32 released = 0;
+	struct sk_buff_head head;
+	struct tipc_node *n_ptr;
+	struct tipc_link *l_ptr;
+	struct sk_buff *skb1, *tmp;
+	struct tipc_msg *msg;
+	u32 seq_no;
+	u32 ackd;
+	u32 released;
 
-		head = head->next;
-		buf->next = NULL;
+	skb2list(skb, &head);
 
+	while ((skb = __skb_dequeue(&head))) {
 		/* Ensure message is well-formed */
-		if (unlikely(!link_recv_buf_validate(buf)))
+		if (unlikely(!link_recv_buf_validate(skb)))
 			goto discard;
 
 		/* Ensure message data is a single contiguous unit */
-		if (unlikely(skb_linearize(buf)))
+		if (unlikely(skb_linearize(skb)))
 			goto discard;
 
 		/* Handle arrival of a non-unicast link message */
-		msg = buf_msg(buf);
+		msg = buf_msg(skb);
 
 		if (unlikely(msg_non_seq(msg))) {
 			if (msg_user(msg) ==  LINK_CONFIG)
-				tipc_disc_rcv(buf, b_ptr);
+				tipc_disc_rcv(skb, b_ptr);
 			else
-				tipc_bclink_rcv(buf);
+				tipc_bclink_rcv(skb);
 			continue;
 		}
 
@@ -1198,22 +1137,19 @@ void tipc_rcv(struct sk_buff *head, struct tipc_bearer *b_ptr)
 		if (n_ptr->bclink.recv_permitted)
 			tipc_bclink_acknowledge(n_ptr, msg_bcast_ack(msg));
 
-		crs = l_ptr->first_out;
-		while ((crs != l_ptr->next_out) &&
-		       less_eq(buf_seqno(crs), ackd)) {
-			struct sk_buff *next = crs->next;
-			kfree_skb(crs);
-			crs = next;
-			released++;
-		}
-		if (released) {
-			l_ptr->first_out = crs;
-			l_ptr->out_queue_size -= released;
+		released = 0;
+		skb_queue_walk_safe(&l_ptr->outqueue, skb1, tmp) {
+			if (skb1 == l_ptr->next_out ||
+			    more(buf_seqno(skb1), ackd))
+				break;
+			 __skb_unlink(skb1, &l_ptr->outqueue);
+			 kfree_skb(skb1);
+			 released = 1;
 		}
 
 		/* Try sending any messages link endpoint has pending */
 		if (unlikely(l_ptr->next_out))
-			tipc_link_push_queue(l_ptr);
+			tipc_link_push_packets(l_ptr);
 
 		if (released && !skb_queue_empty(&l_ptr->waiting_sks)) {
 			link_prepare_wakeup(l_ptr);
@@ -1223,8 +1159,8 @@ void tipc_rcv(struct sk_buff *head, struct tipc_bearer *b_ptr)
 		/* Process the incoming packet */
 		if (unlikely(!link_working_working(l_ptr))) {
 			if (msg_user(msg) == LINK_PROTOCOL) {
-				tipc_link_proto_rcv(l_ptr, buf);
-				head = link_insert_deferred_queue(l_ptr, head);
+				tipc_link_proto_rcv(l_ptr, skb);
+				link_retrieve_defq(l_ptr, &head);
 				tipc_node_unlock(n_ptr);
 				continue;
 			}
@@ -1234,8 +1170,7 @@ void tipc_rcv(struct sk_buff *head, struct tipc_bearer *b_ptr)
 
 			if (link_working_working(l_ptr)) {
 				/* Re-insert buffer in front of queue */
-				buf->next = head;
-				head = buf;
+				__skb_queue_head(&head, skb);
 				tipc_node_unlock(n_ptr);
 				continue;
 			}
@@ -1244,33 +1179,33 @@ void tipc_rcv(struct sk_buff *head, struct tipc_bearer *b_ptr)
 
 		/* Link is now in state WORKING_WORKING */
 		if (unlikely(seq_no != mod(l_ptr->next_in_no))) {
-			link_handle_out_of_seq_msg(l_ptr, buf);
-			head = link_insert_deferred_queue(l_ptr, head);
+			link_handle_out_of_seq_msg(l_ptr, skb);
+			link_retrieve_defq(l_ptr, &head);
 			tipc_node_unlock(n_ptr);
 			continue;
 		}
 		l_ptr->next_in_no++;
-		if (unlikely(l_ptr->oldest_deferred_in))
-			head = link_insert_deferred_queue(l_ptr, head);
+		if (unlikely(!skb_queue_empty(&l_ptr->deferred_queue)))
+			link_retrieve_defq(l_ptr, &head);
 
 		if (unlikely(++l_ptr->unacked_window >= TIPC_MIN_LINK_WIN)) {
 			l_ptr->stats.sent_acks++;
 			tipc_link_proto_xmit(l_ptr, STATE_MSG, 0, 0, 0, 0, 0);
 		}
 
-		if (tipc_link_prepare_input(l_ptr, &buf)) {
+		if (tipc_link_prepare_input(l_ptr, &skb)) {
 			tipc_node_unlock(n_ptr);
 			continue;
 		}
 		tipc_node_unlock(n_ptr);
-		msg = buf_msg(buf);
-		if (tipc_link_input(l_ptr, buf) != 0)
+
+		if (tipc_link_input(l_ptr, skb) != 0)
 			goto discard;
 		continue;
 unlock_discard:
 		tipc_node_unlock(n_ptr);
 discard:
-		kfree_skb(buf);
+		kfree_skb(skb);
 	}
 }
 
@@ -1353,48 +1288,37 @@ static int tipc_link_input(struct tipc_link *l, struct sk_buff *buf)
  *
  * Returns increase in queue length (i.e. 0 or 1)
  */
-u32 tipc_link_defer_pkt(struct sk_buff **head, struct sk_buff **tail,
-			struct sk_buff *buf)
+u32 tipc_link_defer_pkt(struct sk_buff_head *list, struct sk_buff *skb)
 {
-	struct sk_buff *queue_buf;
-	struct sk_buff **prev;
-	u32 seq_no = buf_seqno(buf);
-
-	buf->next = NULL;
+	struct sk_buff *skb1;
+	u32 seq_no = buf_seqno(skb);
 
 	/* Empty queue ? */
-	if (*head == NULL) {
-		*head = *tail = buf;
+	if (skb_queue_empty(list)) {
+		__skb_queue_tail(list, skb);
 		return 1;
 	}
 
 	/* Last ? */
-	if (less(buf_seqno(*tail), seq_no)) {
-		(*tail)->next = buf;
-		*tail = buf;
+	if (less(buf_seqno(skb_peek_tail(list)), seq_no)) {
+		__skb_queue_tail(list, skb);
 		return 1;
 	}
 
 	/* Locate insertion point in queue, then insert; discard if duplicate */
-	prev = head;
-	queue_buf = *head;
-	for (;;) {
-		u32 curr_seqno = buf_seqno(queue_buf);
+	skb_queue_walk(list, skb1) {
+		u32 curr_seqno = buf_seqno(skb1);
 
 		if (seq_no == curr_seqno) {
-			kfree_skb(buf);
+			kfree_skb(skb);
 			return 0;
 		}
 
 		if (less(seq_no, curr_seqno))
 			break;
-
-		prev = &queue_buf->next;
-		queue_buf = queue_buf->next;
 	}
 
-	buf->next = queue_buf;
-	*prev = buf;
+	__skb_queue_before(list, skb1, skb);
 	return 1;
 }
 
@@ -1424,15 +1348,14 @@ static void link_handle_out_of_seq_msg(struct tipc_link *l_ptr,
 		return;
 	}
 
-	if (tipc_link_defer_pkt(&l_ptr->oldest_deferred_in,
-				&l_ptr->newest_deferred_in, buf)) {
-		l_ptr->deferred_inqueue_sz++;
+	if (tipc_link_defer_pkt(&l_ptr->deferred_queue, buf)) {
 		l_ptr->stats.deferred_recv++;
 		TIPC_SKB_CB(buf)->deferred = true;
-		if ((l_ptr->deferred_inqueue_sz % 16) == 1)
+		if ((skb_queue_len(&l_ptr->deferred_queue) % 16) == 1)
 			tipc_link_proto_xmit(l_ptr, STATE_MSG, 0, 0, 0, 0, 0);
-	} else
+	} else {
 		l_ptr->stats.duplicates++;
+	}
 }
 
 /*
@@ -1446,12 +1369,6 @@ void tipc_link_proto_xmit(struct tipc_link *l_ptr, u32 msg_typ, int probe_msg,
 	u32 msg_size = sizeof(l_ptr->proto_msg);
 	int r_flag;
 
-	/* Discard any previous message that was deferred due to congestion */
-	if (l_ptr->proto_msg_queue) {
-		kfree_skb(l_ptr->proto_msg_queue);
-		l_ptr->proto_msg_queue = NULL;
-	}
-
 	/* Don't send protocol message during link changeover */
 	if (l_ptr->exp_msg_count)
 		return;
@@ -1474,8 +1391,8 @@ void tipc_link_proto_xmit(struct tipc_link *l_ptr, u32 msg_typ, int probe_msg,
 		if (l_ptr->next_out)
 			next_sent = buf_seqno(l_ptr->next_out);
 		msg_set_next_sent(msg, next_sent);
-		if (l_ptr->oldest_deferred_in) {
-			u32 rec = buf_seqno(l_ptr->oldest_deferred_in);
+		if (!skb_queue_empty(&l_ptr->deferred_queue)) {
+			u32 rec = buf_seqno(skb_peek(&l_ptr->deferred_queue));
 			gap = mod(rec - mod(l_ptr->next_in_no));
 		}
 		msg_set_seq_gap(msg, gap);
@@ -1663,7 +1580,7 @@ static void tipc_link_proto_rcv(struct tipc_link *l_ptr, struct sk_buff *buf)
 		}
 		if (msg_seq_gap(msg)) {
 			l_ptr->stats.recv_nacks++;
-			tipc_link_retransmit(l_ptr, l_ptr->first_out,
+			tipc_link_retransmit(l_ptr, skb_peek(&l_ptr->outqueue),
 					     msg_seq_gap(msg));
 		}
 		break;
@@ -1682,7 +1599,7 @@ static void tipc_link_tunnel_xmit(struct tipc_link *l_ptr,
 				  u32 selector)
 {
 	struct tipc_link *tunnel;
-	struct sk_buff *buf;
+	struct sk_buff *skb;
 	u32 length = msg_size(msg);
 
 	tunnel = l_ptr->owner->active_links[selector & 1];
@@ -1691,14 +1608,14 @@ static void tipc_link_tunnel_xmit(struct tipc_link *l_ptr,
 		return;
 	}
 	msg_set_size(tunnel_hdr, length + INT_H_SIZE);
-	buf = tipc_buf_acquire(length + INT_H_SIZE);
-	if (!buf) {
+	skb = tipc_buf_acquire(length + INT_H_SIZE);
+	if (!skb) {
 		pr_warn("%sunable to send tunnel msg\n", link_co_err);
 		return;
 	}
-	skb_copy_to_linear_data(buf, tunnel_hdr, INT_H_SIZE);
-	skb_copy_to_linear_data_offset(buf, INT_H_SIZE, msg, length);
-	__tipc_link_xmit(tunnel, buf);
+	skb_copy_to_linear_data(skb, tunnel_hdr, INT_H_SIZE);
+	skb_copy_to_linear_data_offset(skb, INT_H_SIZE, msg, length);
+	__tipc_link_xmit_skb(tunnel, skb);
 }
 
 
@@ -1710,10 +1627,10 @@ static void tipc_link_tunnel_xmit(struct tipc_link *l_ptr,
  */
 void tipc_link_failover_send_queue(struct tipc_link *l_ptr)
 {
-	u32 msgcount = l_ptr->out_queue_size;
-	struct sk_buff *crs = l_ptr->first_out;
+	u32 msgcount = skb_queue_len(&l_ptr->outqueue);
 	struct tipc_link *tunnel = l_ptr->owner->active_links[0];
 	struct tipc_msg tunnel_hdr;
+	struct sk_buff *skb;
 	int split_bundles;
 
 	if (!tunnel)
@@ -1724,14 +1641,12 @@ void tipc_link_failover_send_queue(struct tipc_link *l_ptr)
 	msg_set_bearer_id(&tunnel_hdr, l_ptr->peer_bearer_id);
 	msg_set_msgcnt(&tunnel_hdr, msgcount);
 
-	if (!l_ptr->first_out) {
-		struct sk_buff *buf;
-
-		buf = tipc_buf_acquire(INT_H_SIZE);
-		if (buf) {
-			skb_copy_to_linear_data(buf, &tunnel_hdr, INT_H_SIZE);
+	if (skb_queue_empty(&l_ptr->outqueue)) {
+		skb = tipc_buf_acquire(INT_H_SIZE);
+		if (skb) {
+			skb_copy_to_linear_data(skb, &tunnel_hdr, INT_H_SIZE);
 			msg_set_size(&tunnel_hdr, INT_H_SIZE);
-			__tipc_link_xmit(tunnel, buf);
+			__tipc_link_xmit_skb(tunnel, skb);
 		} else {
 			pr_warn("%sunable to send changeover msg\n",
 				link_co_err);
@@ -1742,8 +1657,8 @@ 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]);
 
-	while (crs) {
-		struct tipc_msg *msg = buf_msg(crs);
+	skb_queue_walk(&l_ptr->outqueue, skb) {
+		struct tipc_msg *msg = buf_msg(skb);
 
 		if ((msg_user(msg) == MSG_BUNDLER) && split_bundles) {
 			struct tipc_msg *m = msg_get_wrapped(msg);
@@ -1761,7 +1676,6 @@ void tipc_link_failover_send_queue(struct tipc_link *l_ptr)
 			tipc_link_tunnel_xmit(l_ptr, &tunnel_hdr, msg,
 					      msg_link_selector(msg));
 		}
-		crs = crs->next;
 	}
 }
 
@@ -1777,17 +1691,16 @@ void tipc_link_failover_send_queue(struct tipc_link *l_ptr)
 void tipc_link_dup_queue_xmit(struct tipc_link *l_ptr,
 			      struct tipc_link *tunnel)
 {
-	struct sk_buff *iter;
+	struct sk_buff *skb;
 	struct tipc_msg tunnel_hdr;
 
 	tipc_msg_init(&tunnel_hdr, CHANGEOVER_PROTOCOL,
 		 DUPLICATE_MSG, INT_H_SIZE, l_ptr->addr);
-	msg_set_msgcnt(&tunnel_hdr, l_ptr->out_queue_size);
+	msg_set_msgcnt(&tunnel_hdr, skb_queue_len(&l_ptr->outqueue));
 	msg_set_bearer_id(&tunnel_hdr, l_ptr->peer_bearer_id);
-	iter = l_ptr->first_out;
-	while (iter) {
-		struct sk_buff *outbuf;
-		struct tipc_msg *msg = buf_msg(iter);
+	skb_queue_walk(&l_ptr->outqueue, skb) {
+		struct sk_buff *outskb;
+		struct tipc_msg *msg = buf_msg(skb);
 		u32 length = msg_size(msg);
 
 		if (msg_user(msg) == MSG_BUNDLER)
@@ -1795,19 +1708,18 @@ void tipc_link_dup_queue_xmit(struct tipc_link *l_ptr,
 		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);
-		outbuf = tipc_buf_acquire(length + INT_H_SIZE);
-		if (outbuf == NULL) {
+		outskb = tipc_buf_acquire(length + INT_H_SIZE);
+		if (outskb == NULL) {
 			pr_warn("%sunable to send duplicate msg\n",
 				link_co_err);
 			return;
 		}
-		skb_copy_to_linear_data(outbuf, &tunnel_hdr, INT_H_SIZE);
-		skb_copy_to_linear_data_offset(outbuf, INT_H_SIZE, iter->data,
+		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(tunnel, outbuf);
+		__tipc_link_xmit_skb(tunnel, outskb);
 		if (!tipc_link_is_up(l_ptr))
 			return;
-		iter = iter->next;
 	}
 }