1 files changed, 326 insertions, 127 deletions

diff --git a/net/tipc/link.c b/net/tipc/link.c
index c2c5c53cad22..467c53a1fb5c 100644
--- a/net/tipc/link.c
+++ b/net/tipc/link.c
@@ -44,6 +44,7 @@
 #include "netlink.h"
 #include "monitor.h"
 #include "trace.h"
+#include "crypto.h"
 
 #include <linux/pkt_sched.h>
 
@@ -160,9 +161,9 @@ struct tipc_link {
 	struct {
 		u16 len;
 		u16 limit;
+		struct sk_buff *target_bskb;
 	} backlog[5];
 	u16 snd_nxt;
-	u16 window;
 
 	/* Reception */
 	u16 rcv_nxt;
@@ -173,9 +174,16 @@ struct tipc_link {
 
 	/* Congestion handling */
 	struct sk_buff_head wakeupq;
+	u16 window;
+	u16 min_win;
+	u16 ssthresh;
+	u16 max_win;
+	u16 cong_acks;
+	u16 checkpoint;
 
 	/* Fragmentation/reassembly */
 	struct sk_buff *reasm_buf;
+	struct sk_buff *reasm_tnlmsg;
 
 	/* Broadcast */
 	u16 ackers;
@@ -241,12 +249,13 @@ static int tipc_link_build_nack_msg(struct tipc_link *l,
 				    struct sk_buff_head *xmitq);
 static void tipc_link_build_bc_init_msg(struct tipc_link *l,
 					struct sk_buff_head *xmitq);
-static bool tipc_link_release_pkts(struct tipc_link *l, u16 to);
-static u16 tipc_build_gap_ack_blks(struct tipc_link *l, void *data);
+static int tipc_link_release_pkts(struct tipc_link *l, u16 to);
+static u16 tipc_build_gap_ack_blks(struct tipc_link *l, void *data, u16 gap);
 static int tipc_link_advance_transmq(struct tipc_link *l, u16 acked, u16 gap,
 				     struct tipc_gap_ack_blks *ga,
 				     struct sk_buff_head *xmitq);
-
+static void tipc_link_update_cwin(struct tipc_link *l, int released,
+				  bool retransmitted);
 /*
  *  Simple non-static link routines (i.e. referenced outside this file)
  */
@@ -305,9 +314,14 @@ u32 tipc_link_id(struct tipc_link *l)
 	return l->peer_bearer_id << 16 | l->bearer_id;
 }
 
-int tipc_link_window(struct tipc_link *l)
+int tipc_link_min_win(struct tipc_link *l)
+{
+	return l->min_win;
+}
+
+int tipc_link_max_win(struct tipc_link *l)
 {
-	return l->window;
+	return l->max_win;
 }
 
 int tipc_link_prio(struct tipc_link *l)
@@ -395,6 +409,15 @@ int tipc_link_mtu(struct tipc_link *l)
 	return l->mtu;
 }
 
+int tipc_link_mss(struct tipc_link *l)
+{
+#ifdef CONFIG_TIPC_CRYPTO
+	return l->mtu - INT_H_SIZE - EMSG_OVERHEAD;
+#else
+	return l->mtu - INT_H_SIZE;
+#endif
+}
+
 u16 tipc_link_rcv_nxt(struct tipc_link *l)
 {
 	return l->rcv_nxt;
@@ -424,7 +447,8 @@ u32 tipc_link_state(struct tipc_link *l)
  * @net_plane: network plane (A,B,c..) this link belongs to
  * @mtu: mtu to be advertised by link
  * @priority: priority to be used by link
- * @window: send window to be used by link
+ * @min_win: minimal send window to be used by link
+ * @max_win: maximal send window to be used by link
  * @session: session to be used by link
  * @ownnode: identity of own node
  * @peer: node id of peer node
@@ -439,7 +463,7 @@ u32 tipc_link_state(struct tipc_link *l)
  */
 bool tipc_link_create(struct net *net, char *if_name, int bearer_id,
 		      int tolerance, char net_plane, u32 mtu, int priority,
-		      int window, u32 session, u32 self,
+		      u32 min_win, u32 max_win, u32 session, u32 self,
 		      u32 peer, u8 *peer_id, u16 peer_caps,
 		      struct tipc_link *bc_sndlink,
 		      struct tipc_link *bc_rcvlink,
@@ -483,7 +507,7 @@ bool tipc_link_create(struct net *net, char *if_name, int bearer_id,
 	l->advertised_mtu = mtu;
 	l->mtu = mtu;
 	l->priority = priority;
-	tipc_link_set_queue_limits(l, window);
+	tipc_link_set_queue_limits(l, min_win, max_win);
 	l->ackers = 1;
 	l->bc_sndlink = bc_sndlink;
 	l->bc_rcvlink = bc_rcvlink;
@@ -511,7 +535,7 @@ bool tipc_link_create(struct net *net, char *if_name, int bearer_id,
  * Returns true if link was created, otherwise false
  */
 bool tipc_link_bc_create(struct net *net, u32 ownnode, u32 peer,
-			 int mtu, int window, u16 peer_caps,
+			 int mtu, u32 min_win, u32 max_win, u16 peer_caps,
 			 struct sk_buff_head *inputq,
 			 struct sk_buff_head *namedq,
 			 struct tipc_link *bc_sndlink,
@@ -519,9 +543,9 @@ bool tipc_link_bc_create(struct net *net, u32 ownnode, u32 peer,
 {
 	struct tipc_link *l;
 
-	if (!tipc_link_create(net, "", MAX_BEARERS, 0, 'Z', mtu, 0, window,
-			      0, ownnode, peer, NULL, peer_caps, bc_sndlink,
-			      NULL, inputq, namedq, link))
+	if (!tipc_link_create(net, "", MAX_BEARERS, 0, 'Z', mtu, 0, min_win,
+			      max_win, 0, ownnode, peer, NULL, peer_caps,
+			      bc_sndlink, NULL, inputq, namedq, link))
 		return false;
 
 	l = *link;
@@ -538,7 +562,7 @@ bool tipc_link_bc_create(struct net *net, u32 ownnode, u32 peer,
 
 	/* Disable replicast if even a single peer doesn't support it */
 	if (link_is_bc_rcvlink(l) && !(peer_caps & TIPC_BCAST_RCAST))
-		tipc_bcast_disable_rcast(net);
+		tipc_bcast_toggle_rcast(net, false);
 
 	return true;
 }
@@ -760,6 +784,8 @@ bool tipc_link_too_silent(struct tipc_link *l)
 	return (l->silent_intv_cnt + 2 > l->abort_limit);
 }
 
+static int tipc_link_bc_retrans(struct tipc_link *l, struct tipc_link *r,
+				u16 from, u16 to, struct sk_buff_head *xmitq);
 /* tipc_link_timeout - perform periodic task as instructed from node timeout
  */
 int tipc_link_timeout(struct tipc_link *l, struct sk_buff_head *xmitq)
@@ -792,6 +818,11 @@ int tipc_link_timeout(struct tipc_link *l, struct sk_buff_head *xmitq)
 		probe |= l->silent_intv_cnt;
 		if (probe || mstate->monitoring)
 			l->silent_intv_cnt++;
+		if (l->snd_nxt == l->checkpoint) {
+			tipc_link_update_cwin(l, 0, 0);
+			probe = true;
+		}
+		l->checkpoint = l->snd_nxt;
 		break;
 	case LINK_RESET:
 		setup = l->rst_cnt++ <= 4;
@@ -849,23 +880,37 @@ static int link_schedule_user(struct tipc_link *l, struct tipc_msg *hdr)
  */
 static void link_prepare_wakeup(struct tipc_link *l)
 {
+	struct sk_buff_head *wakeupq = &l->wakeupq;
+	struct sk_buff_head *inputq = l->inputq;
 	struct sk_buff *skb, *tmp;
-	int imp, i = 0;
+	struct sk_buff_head tmpq;
+	int avail[5] = {0,};
+	int imp = 0;
 
-	skb_queue_walk_safe(&l->wakeupq, skb, tmp) {
+	__skb_queue_head_init(&tmpq);
+
+	for (; imp <= TIPC_SYSTEM_IMPORTANCE; imp++)
+		avail[imp] = l->backlog[imp].limit - l->backlog[imp].len;
+
+	skb_queue_walk_safe(wakeupq, skb, tmp) {
 		imp = TIPC_SKB_CB(skb)->chain_imp;
-		if (l->backlog[imp].len < l->backlog[imp].limit) {
-			skb_unlink(skb, &l->wakeupq);
-			skb_queue_tail(l->inputq, skb);
-		} else if (i++ > 10) {
-			break;
-		}
+		if (avail[imp] <= 0)
+			continue;
+		avail[imp]--;
+		__skb_unlink(skb, wakeupq);
+		__skb_queue_tail(&tmpq, skb);
 	}
+
+	spin_lock_bh(&inputq->lock);
+	skb_queue_splice_tail(&tmpq, inputq);
+	spin_unlock_bh(&inputq->lock);
+
 }
 
 void tipc_link_reset(struct tipc_link *l)
 {
 	struct sk_buff_head list;
+	u32 imp;
 
 	__skb_queue_head_init(&list);
 
@@ -887,14 +932,15 @@ void tipc_link_reset(struct tipc_link *l)
 	__skb_queue_purge(&l->deferdq);
 	__skb_queue_purge(&l->backlogq);
 	__skb_queue_purge(&l->failover_deferdq);
-	l->backlog[TIPC_LOW_IMPORTANCE].len = 0;
-	l->backlog[TIPC_MEDIUM_IMPORTANCE].len = 0;
-	l->backlog[TIPC_HIGH_IMPORTANCE].len = 0;
-	l->backlog[TIPC_CRITICAL_IMPORTANCE].len = 0;
-	l->backlog[TIPC_SYSTEM_IMPORTANCE].len = 0;
+	for (imp = 0; imp <= TIPC_SYSTEM_IMPORTANCE; imp++) {
+		l->backlog[imp].len = 0;
+		l->backlog[imp].target_bskb = NULL;
+	}
 	kfree_skb(l->reasm_buf);
+	kfree_skb(l->reasm_tnlmsg);
 	kfree_skb(l->failover_reasm_skb);
 	l->reasm_buf = NULL;
+	l->reasm_tnlmsg = NULL;
 	l->failover_reasm_skb = NULL;
 	l->rcv_unacked = 0;
 	l->snd_nxt = 1;
@@ -923,20 +969,25 @@ int tipc_link_xmit(struct tipc_link *l, struct sk_buff_head *list,
 		   struct sk_buff_head *xmitq)
 {
 	struct tipc_msg *hdr = buf_msg(skb_peek(list));
-	unsigned int maxwin = l->window;
-	int imp = msg_importance(hdr);
-	unsigned int mtu = l->mtu;
+	struct sk_buff_head *backlogq = &l->backlogq;
+	struct sk_buff_head *transmq = &l->transmq;
+	struct sk_buff *skb, *_skb;
+	u16 bc_ack = l->bc_rcvlink->rcv_nxt - 1;
 	u16 ack = l->rcv_nxt - 1;
 	u16 seqno = l->snd_nxt;
-	u16 bc_ack = l->bc_rcvlink->rcv_nxt - 1;
-	struct sk_buff_head *transmq = &l->transmq;
-	struct sk_buff_head *backlogq = &l->backlogq;
-	struct sk_buff *skb, *_skb, *bskb;
 	int pkt_cnt = skb_queue_len(list);
+	int imp = msg_importance(hdr);
+	unsigned int mss = tipc_link_mss(l);
+	unsigned int cwin = l->window;
+	unsigned int mtu = l->mtu;
+	bool new_bundle;
 	int rc = 0;
 
 	if (unlikely(msg_size(hdr) > mtu)) {
-		skb_queue_purge(list);
+		pr_warn("Too large msg, purging xmit list %d %d %d %d %d!\n",
+			skb_queue_len(list), msg_user(hdr),
+			msg_type(hdr), msg_size(hdr), mtu);
+		__skb_queue_purge(list);
 		return -EMSGSIZE;
 	}
 
@@ -955,20 +1006,18 @@ int tipc_link_xmit(struct tipc_link *l, struct sk_buff_head *list,
 	}
 
 	/* Prepare each packet for sending, and add to relevant queue: */
-	while (skb_queue_len(list)) {
-		skb = skb_peek(list);
-		hdr = buf_msg(skb);
-		msg_set_seqno(hdr, seqno);
-		msg_set_ack(hdr, ack);
-		msg_set_bcast_ack(hdr, bc_ack);
-
-		if (likely(skb_queue_len(transmq) < maxwin)) {
+	while ((skb = __skb_dequeue(list))) {
+		if (likely(skb_queue_len(transmq) < cwin)) {
+			hdr = buf_msg(skb);
+			msg_set_seqno(hdr, seqno);
+			msg_set_ack(hdr, ack);
+			msg_set_bcast_ack(hdr, bc_ack);
 			_skb = skb_clone(skb, GFP_ATOMIC);
 			if (!_skb) {
-				skb_queue_purge(list);
+				kfree_skb(skb);
+				__skb_queue_purge(list);
 				return -ENOBUFS;
 			}
-			__skb_dequeue(list);
 			__skb_queue_tail(transmq, skb);
 			/* next retransmit attempt */
 			if (link_is_bc_sndlink(l))
@@ -980,36 +1029,86 @@ int tipc_link_xmit(struct tipc_link *l, struct sk_buff_head *list,
 			seqno++;
 			continue;
 		}
-		if (tipc_msg_bundle(skb_peek_tail(backlogq), hdr, mtu)) {
-			kfree_skb(__skb_dequeue(list));
-			l->stats.sent_bundled++;
-			continue;
-		}
-		if (tipc_msg_make_bundle(&bskb, hdr, mtu, l->addr)) {
-			kfree_skb(__skb_dequeue(list));
-			__skb_queue_tail(backlogq, bskb);
-			l->backlog[msg_importance(buf_msg(bskb))].len++;
-			l->stats.sent_bundled++;
-			l->stats.sent_bundles++;
+		if (tipc_msg_try_bundle(l->backlog[imp].target_bskb, &skb,
+					mss, l->addr, &new_bundle)) {
+			if (skb) {
+				/* Keep a ref. to the skb for next try */
+				l->backlog[imp].target_bskb = skb;
+				l->backlog[imp].len++;
+				__skb_queue_tail(backlogq, skb);
+			} else {
+				if (new_bundle) {
+					l->stats.sent_bundles++;
+					l->stats.sent_bundled++;
+				}
+				l->stats.sent_bundled++;
+			}
 			continue;
 		}
-		l->backlog[imp].len += skb_queue_len(list);
+		l->backlog[imp].target_bskb = NULL;
+		l->backlog[imp].len += (1 + skb_queue_len(list));
+		__skb_queue_tail(backlogq, skb);
 		skb_queue_splice_tail_init(list, backlogq);
 	}
 	l->snd_nxt = seqno;
 	return rc;
 }
 
+static void tipc_link_update_cwin(struct tipc_link *l, int released,
+				  bool retransmitted)
+{
+	int bklog_len = skb_queue_len(&l->backlogq);
+	struct sk_buff_head *txq = &l->transmq;
+	int txq_len = skb_queue_len(txq);
+	u16 cwin = l->window;
+
+	/* Enter fast recovery */
+	if (unlikely(retransmitted)) {
+		l->ssthresh = max_t(u16, l->window / 2, 300);
+		l->window = l->ssthresh;
+		return;
+	}
+	/* Enter slow start */
+	if (unlikely(!released)) {
+		l->ssthresh = max_t(u16, l->window / 2, 300);
+		l->window = l->min_win;
+		return;
+	}
+	/* Don't increase window if no pressure on the transmit queue */
+	if (txq_len + bklog_len < cwin)
+		return;
+
+	/* Don't increase window if there are holes the transmit queue */
+	if (txq_len && l->snd_nxt - buf_seqno(skb_peek(txq)) != txq_len)
+		return;
+
+	l->cong_acks += released;
+
+	/* Slow start  */
+	if (cwin <= l->ssthresh) {
+		l->window = min_t(u16, cwin + released, l->max_win);
+		return;
+	}
+	/* Congestion avoidance */
+	if (l->cong_acks < cwin)
+		return;
+	l->window = min_t(u16, ++cwin, l->max_win);
+	l->cong_acks = 0;
+}
+
 static void tipc_link_advance_backlog(struct tipc_link *l,
 				      struct sk_buff_head *xmitq)
 {
+	u16 bc_ack = l->bc_rcvlink->rcv_nxt - 1;
+	struct sk_buff_head *txq = &l->transmq;
 	struct sk_buff *skb, *_skb;
-	struct tipc_msg *hdr;
-	u16 seqno = l->snd_nxt;
 	u16 ack = l->rcv_nxt - 1;
-	u16 bc_ack = l->bc_rcvlink->rcv_nxt - 1;
+	u16 seqno = l->snd_nxt;
+	struct tipc_msg *hdr;
+	u16 cwin = l->window;
+	u32 imp;
 
-	while (skb_queue_len(&l->transmq) < l->window) {
+	while (skb_queue_len(txq) < cwin) {
 		skb = skb_peek(&l->backlogq);
 		if (!skb)
 			break;
@@ -1018,7 +1117,10 @@ static void tipc_link_advance_backlog(struct tipc_link *l,
 			break;
 		__skb_dequeue(&l->backlogq);
 		hdr = buf_msg(skb);
-		l->backlog[msg_importance(hdr)].len--;
+		imp = msg_importance(hdr);
+		l->backlog[imp].len--;
+		if (unlikely(skb == l->backlog[imp].target_bskb))
+			l->backlog[imp].target_bskb = NULL;
 		__skb_queue_tail(&l->transmq, skb);
 		/* next retransmit attempt */
 		if (link_is_bc_sndlink(l))
@@ -1058,7 +1160,7 @@ static bool link_retransmit_failure(struct tipc_link *l, struct tipc_link *r,
 		return false;
 
 	if (!time_after(jiffies, TIPC_SKB_CB(skb)->retr_stamp +
-			msecs_to_jiffies(r->tolerance)))
+			msecs_to_jiffies(r->tolerance * 10)))
 		return false;
 
 	hdr = buf_msg(skb);
@@ -1102,6 +1204,7 @@ static int tipc_link_bc_retrans(struct tipc_link *l, struct tipc_link *r,
 	struct sk_buff *_skb, *skb = skb_peek(&l->transmq);
 	u16 bc_ack = l->bc_rcvlink->rcv_nxt - 1;
 	u16 ack = l->rcv_nxt - 1;
+	int retransmitted = 0;
 	struct tipc_msg *hdr;
 	int rc = 0;
 
@@ -1121,11 +1224,10 @@ static int tipc_link_bc_retrans(struct tipc_link *l, struct tipc_link *r,
 			continue;
 		if (more(msg_seqno(hdr), to))
 			break;
-
 		if (time_before(jiffies, TIPC_SKB_CB(skb)->nxt_retr))
 			continue;
 		TIPC_SKB_CB(skb)->nxt_retr = TIPC_BC_RETR_LIM;
-		_skb = __pskb_copy(skb, LL_MAX_HEADER + MIN_H_SIZE, GFP_ATOMIC);
+		_skb = pskb_copy(skb, GFP_ATOMIC);
 		if (!_skb)
 			return 0;
 		hdr = buf_msg(_skb);
@@ -1134,11 +1236,12 @@ static int tipc_link_bc_retrans(struct tipc_link *l, struct tipc_link *r,
 		_skb->priority = TC_PRIO_CONTROL;
 		__skb_queue_tail(xmitq, _skb);
 		l->stats.retransmitted++;
-
+		retransmitted++;
 		/* Increase actual retrans counter & mark first time */
 		if (!TIPC_SKB_CB(skb)->retr_cnt++)
 			TIPC_SKB_CB(skb)->retr_stamp = jiffies;
 	}
+	tipc_link_update_cwin(l, 0, retransmitted);
 	return 0;
 }
 
@@ -1238,6 +1341,7 @@ static int tipc_link_tnl_rcv(struct tipc_link *l, struct sk_buff *skb,
 			     struct sk_buff_head *inputq)
 {
 	struct sk_buff **reasm_skb = &l->failover_reasm_skb;
+	struct sk_buff **reasm_tnlmsg = &l->reasm_tnlmsg;
 	struct sk_buff_head *fdefq = &l->failover_deferdq;
 	struct tipc_msg *hdr = buf_msg(skb);
 	struct sk_buff *iskb;
@@ -1245,46 +1349,62 @@ static int tipc_link_tnl_rcv(struct tipc_link *l, struct sk_buff *skb,
 	int rc = 0;
 	u16 seqno;
 
-	/* SYNCH_MSG */
-	if (msg_type(hdr) == SYNCH_MSG)
-		goto drop;
+	if (msg_type(hdr) == SYNCH_MSG) {
+		kfree_skb(skb);
+		return 0;
+	}
 
-	/* FAILOVER_MSG */
-	if (!tipc_msg_extract(skb, &iskb, &ipos)) {
-		pr_warn_ratelimited("Cannot extract FAILOVER_MSG, defq: %d\n",
-				    skb_queue_len(fdefq));
-		return rc;
+	/* Not a fragment? */
+	if (likely(!msg_nof_fragms(hdr))) {
+		if (unlikely(!tipc_msg_extract(skb, &iskb, &ipos))) {
+			pr_warn_ratelimited("Unable to extract msg, defq: %d\n",
+					    skb_queue_len(fdefq));
+			return 0;
+		}
+		kfree_skb(skb);
+	} else {
+		/* Set fragment type for buf_append */
+		if (msg_fragm_no(hdr) == 1)
+			msg_set_type(hdr, FIRST_FRAGMENT);
+		else if (msg_fragm_no(hdr) < msg_nof_fragms(hdr))
+			msg_set_type(hdr, FRAGMENT);
+		else
+			msg_set_type(hdr, LAST_FRAGMENT);
+
+		if (!tipc_buf_append(reasm_tnlmsg, &skb)) {
+			/* Successful but non-complete reassembly? */
+			if (*reasm_tnlmsg || link_is_bc_rcvlink(l))
+				return 0;
+			pr_warn_ratelimited("Unable to reassemble tunnel msg\n");
+			return tipc_link_fsm_evt(l, LINK_FAILURE_EVT);
+		}
+		iskb = skb;
 	}
 
 	do {
 		seqno = buf_seqno(iskb);
-
 		if (unlikely(less(seqno, l->drop_point))) {
 			kfree_skb(iskb);
 			continue;
 		}
-
 		if (unlikely(seqno != l->drop_point)) {
 			__tipc_skb_queue_sorted(fdefq, seqno, iskb);
 			continue;
 		}
 
 		l->drop_point++;
-
 		if (!tipc_data_input(l, iskb, inputq))
 			rc |= tipc_link_input(l, iskb, inputq, reasm_skb);
 		if (unlikely(rc))
 			break;
 	} while ((iskb = __tipc_skb_dequeue(fdefq, l->drop_point)));
 
-drop:
-	kfree_skb(skb);
 	return rc;
 }
 
-static bool tipc_link_release_pkts(struct tipc_link *l, u16 acked)
+static int tipc_link_release_pkts(struct tipc_link *l, u16 acked)
 {
-	bool released = false;
+	int released = 0;
 	struct sk_buff *skb, *tmp;
 
 	skb_queue_walk_safe(&l->transmq, skb, tmp) {
@@ -1292,7 +1412,7 @@ static bool tipc_link_release_pkts(struct tipc_link *l, u16 acked)
 			break;
 		__skb_unlink(skb, &l->transmq);
 		kfree_skb(skb);
-		released = true;
+		released++;
 	}
 	return released;
 }
@@ -1303,14 +1423,14 @@ static bool tipc_link_release_pkts(struct tipc_link *l, u16 acked)
  *
  * returns the actual allocated memory size
  */
-static u16 tipc_build_gap_ack_blks(struct tipc_link *l, void *data)
+static u16 tipc_build_gap_ack_blks(struct tipc_link *l, void *data, u16 gap)
 {
 	struct sk_buff *skb = skb_peek(&l->deferdq);
 	struct tipc_gap_ack_blks *ga = data;
 	u16 len, expect, seqno = 0;
 	u8 n = 0;
 
-	if (!skb)
+	if (!skb || !gap)
 		goto exit;
 
 	expect = buf_seqno(skb);
@@ -1361,8 +1481,10 @@ static int tipc_link_advance_transmq(struct tipc_link *l, u16 acked, u16 gap,
 	struct sk_buff *skb, *_skb, *tmp;
 	struct tipc_msg *hdr;
 	u16 bc_ack = l->bc_rcvlink->rcv_nxt - 1;
+	bool retransmitted = false;
 	u16 ack = l->rcv_nxt - 1;
 	bool passed = false;
+	u16 released = 0;
 	u16 seqno, n = 0;
 	int rc = 0;
 
@@ -1374,6 +1496,7 @@ next_gap_ack:
 			/* release skb */
 			__skb_unlink(skb, &l->transmq);
 			kfree_skb(skb);
+			released++;
 		} else if (less_eq(seqno, acked + gap)) {
 			/* First, check if repeated retrans failures occurs? */
 			if (!passed && link_retransmit_failure(l, l, &rc))
@@ -1384,8 +1507,7 @@ next_gap_ack:
 			if (time_before(jiffies, TIPC_SKB_CB(skb)->nxt_retr))
 				continue;
 			TIPC_SKB_CB(skb)->nxt_retr = TIPC_UC_RETR_TIME;
-			_skb = __pskb_copy(skb, LL_MAX_HEADER + MIN_H_SIZE,
-					   GFP_ATOMIC);
+			_skb = pskb_copy(skb, GFP_ATOMIC);
 			if (!_skb)
 				continue;
 			hdr = buf_msg(_skb);
@@ -1394,7 +1516,7 @@ next_gap_ack:
 			_skb->priority = TC_PRIO_CONTROL;
 			__skb_queue_tail(xmitq, _skb);
 			l->stats.retransmitted++;
-
+			retransmitted = true;
 			/* Increase actual retrans counter & mark first time */
 			if (!TIPC_SKB_CB(skb)->retr_cnt++)
 				TIPC_SKB_CB(skb)->retr_stamp = jiffies;
@@ -1408,7 +1530,10 @@ next_gap_ack:
 			goto next_gap_ack;
 		}
 	}
-
+	if (released || retransmitted)
+		tipc_link_update_cwin(l, released, retransmitted);
+	if (released)
+		tipc_link_advance_backlog(l, xmitq);
 	return 0;
 }
 
@@ -1432,7 +1557,6 @@ int tipc_link_build_state_msg(struct tipc_link *l, struct sk_buff_head *xmitq)
 		l->snd_nxt = l->rcv_nxt;
 		return TIPC_LINK_SND_STATE;
 	}
-
 	/* Unicast ACK */
 	l->rcv_unacked = 0;
 	l->stats.sent_acks++;
@@ -1466,7 +1590,8 @@ static int tipc_link_build_nack_msg(struct tipc_link *l,
 				    struct sk_buff_head *xmitq)
 {
 	u32 def_cnt = ++l->stats.deferred_recv;
-	u32 defq_len = skb_queue_len(&l->deferdq);
+	struct sk_buff_head *dfq = &l->deferdq;
+	u32 defq_len = skb_queue_len(dfq);
 	int match1, match2;
 
 	if (link_is_bc_rcvlink(l)) {
@@ -1477,8 +1602,12 @@ static int tipc_link_build_nack_msg(struct tipc_link *l,
 		return 0;
 	}
 
-	if (defq_len >= 3 && !((defq_len - 3) % 16))
-		tipc_link_build_proto_msg(l, STATE_MSG, 0, 0, 0, 0, 0, xmitq);
+	if (defq_len >= 3 && !((defq_len - 3) % 16)) {
+		u16 rcvgap = buf_seqno(skb_peek(dfq)) - l->rcv_nxt;
+
+		tipc_link_build_proto_msg(l, STATE_MSG, 0, 0,
+					  rcvgap, 0, 0, xmitq);
+	}
 	return 0;
 }
 
@@ -1493,6 +1622,7 @@ int tipc_link_rcv(struct tipc_link *l, struct sk_buff *skb,
 	struct sk_buff_head *defq = &l->deferdq;
 	struct tipc_msg *hdr = buf_msg(skb);
 	u16 seqno, rcv_nxt, win_lim;
+	int released = 0;
 	int rc = 0;
 
 	/* Verify and update link state */
@@ -1511,21 +1641,17 @@ int tipc_link_rcv(struct tipc_link *l, struct sk_buff *skb,
 		if (unlikely(!link_is_up(l))) {
 			if (l->state == LINK_ESTABLISHING)
 				rc = TIPC_LINK_UP_EVT;
-			goto drop;
+			kfree_skb(skb);
+			break;
 		}
 
 		/* Drop if outside receive window */
 		if (unlikely(less(seqno, rcv_nxt) || more(seqno, win_lim))) {
 			l->stats.duplicates++;
-			goto drop;
-		}
-
-		/* Forward queues and wake up waiting users */
-		if (likely(tipc_link_release_pkts(l, msg_ack(hdr)))) {
-			tipc_link_advance_backlog(l, xmitq);
-			if (unlikely(!skb_queue_empty(&l->wakeupq)))
-				link_prepare_wakeup(l);
+			kfree_skb(skb);
+			break;
 		}
+		released += tipc_link_release_pkts(l, msg_ack(hdr));
 
 		/* Defer delivery if sequence gap */
 		if (unlikely(seqno != rcv_nxt)) {
@@ -1548,9 +1674,13 @@ int tipc_link_rcv(struct tipc_link *l, struct sk_buff *skb,
 			break;
 	} while ((skb = __tipc_skb_dequeue(defq, l->rcv_nxt)));
 
-	return rc;
-drop:
-	kfree_skb(skb);
+	/* Forward queues and wake up waiting users */
+	if (released) {
+		tipc_link_update_cwin(l, released, 0);
+		tipc_link_advance_backlog(l, xmitq);
+		if (unlikely(!skb_queue_empty(&l->wakeupq)))
+			link_prepare_wakeup(l);
+	}
 	return rc;
 }
 
@@ -1576,7 +1706,7 @@ static void tipc_link_build_proto_msg(struct tipc_link *l, int mtyp, bool probe,
 	if (!tipc_link_is_up(l) && (mtyp == STATE_MSG))
 		return;
 
-	if (!skb_queue_empty(dfq))
+	if ((probe || probe_reply) && !skb_queue_empty(dfq))
 		rcvgap = buf_seqno(skb_peek(dfq)) - l->rcv_nxt;
 
 	skb = tipc_msg_create(LINK_PROTOCOL, mtyp, INT_H_SIZE,
@@ -1609,7 +1739,7 @@ static void tipc_link_build_proto_msg(struct tipc_link *l, int mtyp, bool probe,
 		msg_set_probe(hdr, probe);
 		msg_set_is_keepalive(hdr, probe || probe_reply);
 		if (l->peer_caps & TIPC_GAP_ACK_BLOCK)
-			glen = tipc_build_gap_ack_blks(l, data);
+			glen = tipc_build_gap_ack_blks(l, data, rcvgap);
 		tipc_mon_prep(l->net, data + glen, &dlen, mstate, l->bearer_id);
 		msg_set_size(hdr, INT_H_SIZE + glen + dlen);
 		skb_trim(skb, INT_H_SIZE + glen + dlen);
@@ -1644,7 +1774,7 @@ void tipc_link_create_dummy_tnl_msg(struct tipc_link *l,
 	struct sk_buff *skb;
 	u32 dnode = l->addr;
 
-	skb_queue_head_init(&tnlq);
+	__skb_queue_head_init(&tnlq);
 	skb = tipc_msg_create(TUNNEL_PROTOCOL, FAILOVER_MSG,
 			      INT_H_SIZE, BASIC_H_SIZE,
 			      dnode, onode, 0, 0, 0);
@@ -1675,15 +1805,43 @@ void tipc_link_tnl_prepare(struct tipc_link *l, struct tipc_link *tnl,
 	struct sk_buff *skb, *tnlskb;
 	struct tipc_msg *hdr, tnlhdr;
 	struct sk_buff_head *queue = &l->transmq;
-	struct sk_buff_head tmpxq, tnlq;
+	struct sk_buff_head tmpxq, tnlq, frags;
 	u16 pktlen, pktcnt, seqno = l->snd_nxt;
+	bool pktcnt_need_update = false;
+	u16 syncpt;
+	int rc;
 
 	if (!tnl)
 		return;
 
-	skb_queue_head_init(&tnlq);
-	skb_queue_head_init(&tmpxq);
+	__skb_queue_head_init(&tnlq);
+	/* Link Synching:
+	 * From now on, send only one single ("dummy") SYNCH message
+	 * to peer. The SYNCH message does not contain any data, just
+	 * a header conveying the synch point to the peer.
+	 */
+	if (mtyp == SYNCH_MSG && (tnl->peer_caps & TIPC_TUNNEL_ENHANCED)) {
+		tnlskb = tipc_msg_create(TUNNEL_PROTOCOL, SYNCH_MSG,
+					 INT_H_SIZE, 0, l->addr,
+					 tipc_own_addr(l->net),
+					 0, 0, 0);
+		if (!tnlskb) {
+			pr_warn("%sunable to create dummy SYNCH_MSG\n",
+				link_co_err);
+			return;
+		}
+
+		hdr = buf_msg(tnlskb);
+		syncpt = l->snd_nxt + skb_queue_len(&l->backlogq) - 1;
+		msg_set_syncpt(hdr, syncpt);
+		msg_set_bearer_id(hdr, l->peer_bearer_id);
+		__skb_queue_tail(&tnlq, tnlskb);
+		tipc_link_xmit(tnl, &tnlq, xmitq);
+		return;
+	}
 
+	__skb_queue_head_init(&tmpxq);
+	__skb_queue_head_init(&frags);
 	/* At least one packet required for safe algorithm => add dummy */
 	skb = tipc_msg_create(TIPC_LOW_IMPORTANCE, TIPC_DIRECT_MSG,
 			      BASIC_H_SIZE, 0, l->addr, tipc_own_addr(l->net),
@@ -1692,7 +1850,7 @@ void tipc_link_tnl_prepare(struct tipc_link *l, struct tipc_link *tnl,
 		pr_warn("%sunable to create tunnel packet\n", link_co_err);
 		return;
 	}
-	skb_queue_tail(&tnlq, skb);
+	__skb_queue_tail(&tnlq, skb);
 	tipc_link_xmit(l, &tnlq, &tmpxq);
 	__skb_queue_purge(&tmpxq);
 
@@ -1713,6 +1871,39 @@ tnl:
 		if (queue == &l->backlogq)
 			msg_set_seqno(hdr, seqno++);
 		pktlen = msg_size(hdr);
+
+		/* Tunnel link MTU is not large enough? This could be
+		 * due to:
+		 * 1) Link MTU has just changed or set differently;
+		 * 2) Or FAILOVER on the top of a SYNCH message
+		 *
+		 * The 2nd case should not happen if peer supports
+		 * TIPC_TUNNEL_ENHANCED
+		 */
+		if (pktlen > tnl->mtu - INT_H_SIZE) {
+			if (mtyp == FAILOVER_MSG &&
+			    (tnl->peer_caps & TIPC_TUNNEL_ENHANCED)) {
+				rc = tipc_msg_fragment(skb, &tnlhdr, tnl->mtu,
+						       &frags);
+				if (rc) {
+					pr_warn("%sunable to frag msg: rc %d\n",
+						link_co_err, rc);
+					return;
+				}
+				pktcnt += skb_queue_len(&frags) - 1;
+				pktcnt_need_update = true;
+				skb_queue_splice_tail_init(&frags, &tnlq);
+				continue;
+			}
+			/* Unluckily, peer doesn't have TIPC_TUNNEL_ENHANCED
+			 * => Just warn it and return!
+			 */
+			pr_warn_ratelimited("%stoo large msg <%d, %d>: %d!\n",
+					    link_co_err, msg_user(hdr),
+					    msg_type(hdr), msg_size(hdr));
+			return;
+		}
+
 		msg_set_size(&tnlhdr, pktlen + INT_H_SIZE);
 		tnlskb = tipc_buf_acquire(pktlen + INT_H_SIZE, GFP_ATOMIC);
 		if (!tnlskb) {
@@ -1728,6 +1919,12 @@ tnl:
 		goto tnl;
 	}
 
+	if (pktcnt_need_update)
+		skb_queue_walk(&tnlq, skb) {
+			hdr = buf_msg(skb);
+			msg_set_msgcnt(hdr, pktcnt);
+		}
+
 	tipc_link_xmit(tnl, &tnlq, xmitq);
 
 	if (mtyp == FAILOVER_MSG) {
@@ -1762,7 +1959,7 @@ void tipc_link_failover_prepare(struct tipc_link *l, struct tipc_link *tnl,
 
 	tipc_link_create_dummy_tnl_msg(tnl, xmitq);
 
-	/* This failover link enpoint was never established before,
+	/* This failover link endpoint was never established before,
 	 * so it has not received anything from peer.
 	 * Otherwise, it must be a normal failover situation or the
 	 * node has entered SELF_DOWN_PEER_LEAVING and both peer nodes
@@ -1952,19 +2149,18 @@ static int tipc_link_proto_rcv(struct tipc_link *l, struct sk_buff *skb,
 			     &l->mon_state, l->bearer_id);
 
 		/* Send NACK if peer has sent pkts we haven't received yet */
-		if (more(peers_snd_nxt, rcv_nxt) && !tipc_link_is_synching(l))
+		if ((reply || msg_is_keepalive(hdr)) &&
+		    more(peers_snd_nxt, rcv_nxt) &&
+		    !tipc_link_is_synching(l) &&
+		    skb_queue_empty(&l->deferdq))
 			rcvgap = peers_snd_nxt - l->rcv_nxt;
 		if (rcvgap || reply)
 			tipc_link_build_proto_msg(l, STATE_MSG, 0, reply,
 						  rcvgap, 0, 0, xmitq);
 
 		rc |= tipc_link_advance_transmq(l, ack, gap, ga, xmitq);
-
-		/* If NACK, retransmit will now start at right position */
 		if (gap)
 			l->stats.recv_nacks++;
-
-		tipc_link_advance_backlog(l, xmitq);
 		if (unlikely(!skb_queue_empty(&l->wakeupq)))
 			link_prepare_wakeup(l);
 	}
@@ -2183,15 +2379,18 @@ int tipc_link_bc_nack_rcv(struct tipc_link *l, struct sk_buff *skb,
 	return 0;
 }
 
-void tipc_link_set_queue_limits(struct tipc_link *l, u32 win)
+void tipc_link_set_queue_limits(struct tipc_link *l, u32 min_win, u32 max_win)
 {
 	int max_bulk = TIPC_MAX_PUBL / (l->mtu / ITEM_SIZE);
 
-	l->window = win;
-	l->backlog[TIPC_LOW_IMPORTANCE].limit      = max_t(u16, 50, win);
-	l->backlog[TIPC_MEDIUM_IMPORTANCE].limit   = max_t(u16, 100, win * 2);
-	l->backlog[TIPC_HIGH_IMPORTANCE].limit     = max_t(u16, 150, win * 3);
-	l->backlog[TIPC_CRITICAL_IMPORTANCE].limit = max_t(u16, 200, win * 4);
+	l->min_win = min_win;
+	l->ssthresh = max_win;
+	l->max_win = max_win;
+	l->window = min_win;
+	l->backlog[TIPC_LOW_IMPORTANCE].limit      = min_win * 2;
+	l->backlog[TIPC_MEDIUM_IMPORTANCE].limit   = min_win * 4;
+	l->backlog[TIPC_HIGH_IMPORTANCE].limit     = min_win * 6;
+	l->backlog[TIPC_CRITICAL_IMPORTANCE].limit = min_win * 8;
 	l->backlog[TIPC_SYSTEM_IMPORTANCE].limit   = max_bulk;
 }
 
@@ -2244,10 +2443,10 @@ int tipc_nl_parse_link_prop(struct nlattr *prop, struct nlattr *props[])
 	}
 
 	if (props[TIPC_NLA_PROP_WIN]) {
-		u32 win;
+		u32 max_win;
 
-		win = nla_get_u32(props[TIPC_NLA_PROP_WIN]);
-		if ((win < TIPC_MIN_LINK_WIN) || (win > TIPC_MAX_LINK_WIN))
+		max_win = nla_get_u32(props[TIPC_NLA_PROP_WIN]);
+		if (max_win < TIPC_DEF_LINK_WIN || max_win > TIPC_MAX_LINK_WIN)
 			return -EINVAL;
 	}
 
@@ -2483,7 +2682,7 @@ int tipc_nl_add_bc_link(struct net *net, struct tipc_nl_msg *msg)
 	prop = nla_nest_start_noflag(msg->skb, TIPC_NLA_LINK_PROP);
 	if (!prop)
 		goto attr_msg_full;
-	if (nla_put_u32(msg->skb, TIPC_NLA_PROP_WIN, bcl->window))
+	if (nla_put_u32(msg->skb, TIPC_NLA_PROP_WIN, bcl->max_win))
 		goto prop_msg_full;
 	if (nla_put_u32(msg->skb, TIPC_NLA_PROP_BROADCAST, bc_mode))
 		goto prop_msg_full;