Adding upstream version 4.19.249.upstream/4.19.249

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 2285 insertions, 0 deletions

diff --git a/net/tipc/link.c b/net/tipc/link.c
new file mode 100644
index 000000000..0d2ee4eb1
--- /dev/null
+++ b/net/tipc/link.c
@@ -0,0 +1,2285 @@
+/*
+ * net/tipc/link.c: TIPC link code
+ *
+ * Copyright (c) 1996-2007, 2012-2016, Ericsson AB
+ * Copyright (c) 2004-2007, 2010-2013, Wind River Systems
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ * 3. Neither the names of the copyright holders nor the names of its
+ *    contributors may be used to endorse or promote products derived from
+ *    this software without specific prior written permission.
+ *
+ * Alternatively, this software may be distributed under the terms of the
+ * GNU General Public License ("GPL") version 2 as published by the Free
+ * Software Foundation.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
+ * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+ * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+ * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+ * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+ * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include "core.h"
+#include "subscr.h"
+#include "link.h"
+#include "bcast.h"
+#include "socket.h"
+#include "name_distr.h"
+#include "discover.h"
+#include "netlink.h"
+#include "monitor.h"
+
+#include <linux/pkt_sched.h>
+
+struct tipc_stats {
+	u32 sent_pkts;
+	u32 recv_pkts;
+	u32 sent_states;
+	u32 recv_states;
+	u32 sent_probes;
+	u32 recv_probes;
+	u32 sent_nacks;
+	u32 recv_nacks;
+	u32 sent_acks;
+	u32 sent_bundled;
+	u32 sent_bundles;
+	u32 recv_bundled;
+	u32 recv_bundles;
+	u32 retransmitted;
+	u32 sent_fragmented;
+	u32 sent_fragments;
+	u32 recv_fragmented;
+	u32 recv_fragments;
+	u32 link_congs;		/* # port sends blocked by congestion */
+	u32 deferred_recv;
+	u32 duplicates;
+	u32 max_queue_sz;	/* send queue size high water mark */
+	u32 accu_queue_sz;	/* used for send queue size profiling */
+	u32 queue_sz_counts;	/* used for send queue size profiling */
+	u32 msg_length_counts;	/* used for message length profiling */
+	u32 msg_lengths_total;	/* used for message length profiling */
+	u32 msg_length_profile[7]; /* used for msg. length profiling */
+};
+
+/**
+ * struct tipc_link - TIPC link data structure
+ * @addr: network address of link's peer node
+ * @name: link name character string
+ * @media_addr: media address to use when sending messages over link
+ * @timer: link timer
+ * @net: pointer to namespace struct
+ * @refcnt: reference counter for permanent references (owner node & timer)
+ * @peer_session: link session # being used by peer end of link
+ * @peer_bearer_id: bearer id used by link's peer endpoint
+ * @bearer_id: local bearer id used by link
+ * @tolerance: minimum link continuity loss needed to reset link [in ms]
+ * @abort_limit: # of unacknowledged continuity probes needed to reset link
+ * @state: current state of link FSM
+ * @peer_caps: bitmap describing capabilities of peer node
+ * @silent_intv_cnt: # of timer intervals without any reception from peer
+ * @proto_msg: template for control messages generated by link
+ * @pmsg: convenience pointer to "proto_msg" field
+ * @priority: current link priority
+ * @net_plane: current link network plane ('A' through 'H')
+ * @mon_state: cookie with information needed by link monitor
+ * @backlog_limit: backlog queue congestion thresholds (indexed by importance)
+ * @exp_msg_count: # of tunnelled messages expected during link changeover
+ * @reset_rcv_checkpt: seq # of last acknowledged message at time of link reset
+ * @mtu: current maximum packet size for this link
+ * @advertised_mtu: advertised own mtu when link is being established
+ * @transmitq: queue for sent, non-acked messages
+ * @backlogq: queue for messages waiting to be sent
+ * @snt_nxt: next sequence number to use for outbound messages
+ * @last_retransmitted: sequence number of most recently retransmitted message
+ * @stale_cnt: counter for number of identical retransmit attempts
+ * @stale_limit: time when repeated identical retransmits must force link reset
+ * @ackers: # of peers that needs to ack each packet before it can be released
+ * @acked: # last packet acked by a certain peer. Used for broadcast.
+ * @rcv_nxt: next sequence number to expect for inbound messages
+ * @deferred_queue: deferred queue saved OOS b'cast message received from node
+ * @unacked_window: # of inbound messages rx'd without ack'ing back to peer
+ * @inputq: buffer queue for messages to be delivered upwards
+ * @namedq: buffer queue for name table messages to be delivered upwards
+ * @next_out: ptr to first unsent outbound message in queue
+ * @wakeupq: linked list of wakeup msgs waiting for link congestion to abate
+ * @long_msg_seq_no: next identifier to use for outbound fragmented messages
+ * @reasm_buf: head of partially reassembled inbound message fragments
+ * @bc_rcvr: marks that this is a broadcast receiver link
+ * @stats: collects statistics regarding link activity
+ */
+struct tipc_link {
+	u32 addr;
+	char name[TIPC_MAX_LINK_NAME];
+	struct net *net;
+
+	/* Management and link supervision data */
+	u16 peer_session;
+	u16 session;
+	u16 snd_nxt_state;
+	u16 rcv_nxt_state;
+	u32 peer_bearer_id;
+	u32 bearer_id;
+	u32 tolerance;
+	u32 abort_limit;
+	u32 state;
+	u16 peer_caps;
+	bool in_session;
+	bool active;
+	u32 silent_intv_cnt;
+	char if_name[TIPC_MAX_IF_NAME];
+	u32 priority;
+	char net_plane;
+	struct tipc_mon_state mon_state;
+	u16 rst_cnt;
+
+	/* Failover/synch */
+	u16 drop_point;
+	struct sk_buff *failover_reasm_skb;
+
+	/* Max packet negotiation */
+	u16 mtu;
+	u16 advertised_mtu;
+
+	/* Sending */
+	struct sk_buff_head transmq;
+	struct sk_buff_head backlogq;
+	struct {
+		u16 len;
+		u16 limit;
+		struct sk_buff *target_bskb;
+	} backlog[5];
+	u16 snd_nxt;
+	u16 last_retransm;
+	u16 window;
+	u16 stale_cnt;
+	unsigned long stale_limit;
+
+	/* Reception */
+	u16 rcv_nxt;
+	u32 rcv_unacked;
+	struct sk_buff_head deferdq;
+	struct sk_buff_head *inputq;
+	struct sk_buff_head *namedq;
+
+	/* Congestion handling */
+	struct sk_buff_head wakeupq;
+
+	/* Fragmentation/reassembly */
+	struct sk_buff *reasm_buf;
+
+	/* Broadcast */
+	u16 ackers;
+	u16 acked;
+	struct tipc_link *bc_rcvlink;
+	struct tipc_link *bc_sndlink;
+	unsigned long prev_retr;
+	u16 prev_from;
+	u16 prev_to;
+	u8 nack_state;
+	bool bc_peer_is_up;
+
+	/* Statistics */
+	struct tipc_stats stats;
+};
+
+/*
+ * Error message prefixes
+ */
+static const char *link_co_err = "Link tunneling error, ";
+static const char *link_rst_msg = "Resetting link ";
+
+/* Send states for broadcast NACKs
+ */
+enum {
+	BC_NACK_SND_CONDITIONAL,
+	BC_NACK_SND_UNCONDITIONAL,
+	BC_NACK_SND_SUPPRESS,
+};
+
+#define TIPC_BC_RETR_LIMIT 10   /* [ms] */
+
+/*
+ * Interval between NACKs when packets arrive out of order
+ */
+#define TIPC_NACK_INTV (TIPC_MIN_LINK_WIN * 2)
+
+/* Link FSM states:
+ */
+enum {
+	LINK_ESTABLISHED     = 0xe,
+	LINK_ESTABLISHING    = 0xe  << 4,
+	LINK_RESET           = 0x1  << 8,
+	LINK_RESETTING       = 0x2  << 12,
+	LINK_PEER_RESET      = 0xd  << 16,
+	LINK_FAILINGOVER     = 0xf  << 20,
+	LINK_SYNCHING        = 0xc  << 24
+};
+
+/* Link FSM state checking routines
+ */
+static int link_is_up(struct tipc_link *l)
+{
+	return l->state & (LINK_ESTABLISHED | LINK_SYNCHING);
+}
+
+static int tipc_link_proto_rcv(struct tipc_link *l, struct sk_buff *skb,
+			       struct sk_buff_head *xmitq);
+static void tipc_link_build_proto_msg(struct tipc_link *l, int mtyp, bool probe,
+				      bool probe_reply, u16 rcvgap,
+				      int tolerance, int priority,
+				      struct sk_buff_head *xmitq);
+static void link_print(struct tipc_link *l, const char *str);
+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);
+
+/*
+ *  Simple non-static link routines (i.e. referenced outside this file)
+ */
+bool tipc_link_is_up(struct tipc_link *l)
+{
+	return link_is_up(l);
+}
+
+bool tipc_link_peer_is_down(struct tipc_link *l)
+{
+	return l->state == LINK_PEER_RESET;
+}
+
+bool tipc_link_is_reset(struct tipc_link *l)
+{
+	return l->state & (LINK_RESET | LINK_FAILINGOVER | LINK_ESTABLISHING);
+}
+
+bool tipc_link_is_establishing(struct tipc_link *l)
+{
+	return l->state == LINK_ESTABLISHING;
+}
+
+bool tipc_link_is_synching(struct tipc_link *l)
+{
+	return l->state == LINK_SYNCHING;
+}
+
+bool tipc_link_is_failingover(struct tipc_link *l)
+{
+	return l->state == LINK_FAILINGOVER;
+}
+
+bool tipc_link_is_blocked(struct tipc_link *l)
+{
+	return l->state & (LINK_RESETTING | LINK_PEER_RESET | LINK_FAILINGOVER);
+}
+
+static bool link_is_bc_sndlink(struct tipc_link *l)
+{
+	return !l->bc_sndlink;
+}
+
+static bool link_is_bc_rcvlink(struct tipc_link *l)
+{
+	return ((l->bc_rcvlink == l) && !link_is_bc_sndlink(l));
+}
+
+void tipc_link_set_active(struct tipc_link *l, bool active)
+{
+	l->active = active;
+}
+
+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)
+{
+	return l->window;
+}
+
+int tipc_link_prio(struct tipc_link *l)
+{
+	return l->priority;
+}
+
+unsigned long tipc_link_tolerance(struct tipc_link *l)
+{
+	return l->tolerance;
+}
+
+struct sk_buff_head *tipc_link_inputq(struct tipc_link *l)
+{
+	return l->inputq;
+}
+
+char tipc_link_plane(struct tipc_link *l)
+{
+	return l->net_plane;
+}
+
+void tipc_link_update_caps(struct tipc_link *l, u16 capabilities)
+{
+	l->peer_caps = capabilities;
+}
+
+void tipc_link_add_bc_peer(struct tipc_link *snd_l,
+			   struct tipc_link *uc_l,
+			   struct sk_buff_head *xmitq)
+{
+	struct tipc_link *rcv_l = uc_l->bc_rcvlink;
+
+	snd_l->ackers++;
+	rcv_l->acked = snd_l->snd_nxt - 1;
+	snd_l->state = LINK_ESTABLISHED;
+	tipc_link_build_bc_init_msg(uc_l, xmitq);
+}
+
+void tipc_link_remove_bc_peer(struct tipc_link *snd_l,
+			      struct tipc_link *rcv_l,
+			      struct sk_buff_head *xmitq)
+{
+	u16 ack = snd_l->snd_nxt - 1;
+
+	snd_l->ackers--;
+	rcv_l->bc_peer_is_up = true;
+	rcv_l->state = LINK_ESTABLISHED;
+	tipc_link_bc_ack_rcv(rcv_l, ack, xmitq);
+	tipc_link_reset(rcv_l);
+	rcv_l->state = LINK_RESET;
+	if (!snd_l->ackers) {
+		tipc_link_reset(snd_l);
+		snd_l->state = LINK_RESET;
+		__skb_queue_purge(xmitq);
+	}
+}
+
+int tipc_link_bc_peers(struct tipc_link *l)
+{
+	return l->ackers;
+}
+
+static u16 link_bc_rcv_gap(struct tipc_link *l)
+{
+	struct sk_buff *skb = skb_peek(&l->deferdq);
+	u16 gap = 0;
+
+	if (more(l->snd_nxt, l->rcv_nxt))
+		gap = l->snd_nxt - l->rcv_nxt;
+	if (skb)
+		gap = buf_seqno(skb) - l->rcv_nxt;
+	return gap;
+}
+
+void tipc_link_set_mtu(struct tipc_link *l, int mtu)
+{
+	l->mtu = mtu;
+}
+
+int tipc_link_mtu(struct tipc_link *l)
+{
+	return l->mtu;
+}
+
+u16 tipc_link_rcv_nxt(struct tipc_link *l)
+{
+	return l->rcv_nxt;
+}
+
+u16 tipc_link_acked(struct tipc_link *l)
+{
+	return l->acked;
+}
+
+char *tipc_link_name(struct tipc_link *l)
+{
+	return l->name;
+}
+
+u32 tipc_link_state(struct tipc_link *l)
+{
+	return l->state;
+}
+
+/**
+ * tipc_link_create - create a new link
+ * @n: pointer to associated node
+ * @if_name: associated interface name
+ * @bearer_id: id (index) of associated bearer
+ * @tolerance: link tolerance to be used by link
+ * @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
+ * @session: session to be used by link
+ * @ownnode: identity of own node
+ * @peer: node id of peer node
+ * @peer_caps: bitmap describing peer node capabilities
+ * @bc_sndlink: the namespace global link used for broadcast sending
+ * @bc_rcvlink: the peer specific link used for broadcast reception
+ * @inputq: queue to put messages ready for delivery
+ * @namedq: queue to put binding table update messages ready for delivery
+ * @link: return value, pointer to put the created link
+ *
+ * Returns true if link was created, otherwise false
+ */
+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 peer, u8 *peer_id, u16 peer_caps,
+		      struct tipc_link *bc_sndlink,
+		      struct tipc_link *bc_rcvlink,
+		      struct sk_buff_head *inputq,
+		      struct sk_buff_head *namedq,
+		      struct tipc_link **link)
+{
+	char peer_str[NODE_ID_STR_LEN] = {0,};
+	char self_str[NODE_ID_STR_LEN] = {0,};
+	struct tipc_link *l;
+
+	l = kzalloc(sizeof(*l), GFP_ATOMIC);
+	if (!l)
+		return false;
+	*link = l;
+	l->session = session;
+
+	/* Set link name for unicast links only */
+	if (peer_id) {
+		tipc_nodeid2string(self_str, tipc_own_id(net));
+		if (strlen(self_str) > 16)
+			sprintf(self_str, "%x", self);
+		tipc_nodeid2string(peer_str, peer_id);
+		if (strlen(peer_str) > 16)
+			sprintf(peer_str, "%x", peer);
+	}
+	/* Peer i/f name will be completed by reset/activate message */
+	snprintf(l->name, sizeof(l->name), "%s:%s-%s:unknown",
+		 self_str, if_name, peer_str);
+
+	strcpy(l->if_name, if_name);
+	l->addr = peer;
+	l->peer_caps = peer_caps;
+	l->net = net;
+	l->in_session = false;
+	l->bearer_id = bearer_id;
+	l->tolerance = tolerance;
+	if (bc_rcvlink)
+		bc_rcvlink->tolerance = tolerance;
+	l->net_plane = net_plane;
+	l->advertised_mtu = mtu;
+	l->mtu = mtu;
+	l->priority = priority;
+	tipc_link_set_queue_limits(l, window);
+	l->ackers = 1;
+	l->bc_sndlink = bc_sndlink;
+	l->bc_rcvlink = bc_rcvlink;
+	l->inputq = inputq;
+	l->namedq = namedq;
+	l->state = LINK_RESETTING;
+	__skb_queue_head_init(&l->transmq);
+	__skb_queue_head_init(&l->backlogq);
+	__skb_queue_head_init(&l->deferdq);
+	skb_queue_head_init(&l->wakeupq);
+	skb_queue_head_init(l->inputq);
+	return true;
+}
+
+/**
+ * tipc_link_bc_create - create new link to be used for broadcast
+ * @n: pointer to associated node
+ * @mtu: mtu to be used initially if no peers
+ * @window: send window to be used
+ * @inputq: queue to put messages ready for delivery
+ * @namedq: queue to put binding table update messages ready for delivery
+ * @link: return value, pointer to put the created link
+ *
+ * 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,
+			 struct sk_buff_head *inputq,
+			 struct sk_buff_head *namedq,
+			 struct tipc_link *bc_sndlink,
+			 struct tipc_link **link)
+{
+	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))
+		return false;
+
+	l = *link;
+	strcpy(l->name, tipc_bclink_name);
+	tipc_link_reset(l);
+	l->state = LINK_RESET;
+	l->ackers = 0;
+	l->bc_rcvlink = l;
+
+	/* Broadcast send link is always up */
+	if (link_is_bc_sndlink(l))
+		l->state = LINK_ESTABLISHED;
+
+	/* 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);
+
+	return true;
+}
+
+/**
+ * tipc_link_fsm_evt - link finite state machine
+ * @l: pointer to link
+ * @evt: state machine event to be processed
+ */
+int tipc_link_fsm_evt(struct tipc_link *l, int evt)
+{
+	int rc = 0;
+
+	switch (l->state) {
+	case LINK_RESETTING:
+		switch (evt) {
+		case LINK_PEER_RESET_EVT:
+			l->state = LINK_PEER_RESET;
+			break;
+		case LINK_RESET_EVT:
+			l->state = LINK_RESET;
+			break;
+		case LINK_FAILURE_EVT:
+		case LINK_FAILOVER_BEGIN_EVT:
+		case LINK_ESTABLISH_EVT:
+		case LINK_FAILOVER_END_EVT:
+		case LINK_SYNCH_BEGIN_EVT:
+		case LINK_SYNCH_END_EVT:
+		default:
+			goto illegal_evt;
+		}
+		break;
+	case LINK_RESET:
+		switch (evt) {
+		case LINK_PEER_RESET_EVT:
+			l->state = LINK_ESTABLISHING;
+			break;
+		case LINK_FAILOVER_BEGIN_EVT:
+			l->state = LINK_FAILINGOVER;
+		case LINK_FAILURE_EVT:
+		case LINK_RESET_EVT:
+		case LINK_ESTABLISH_EVT:
+		case LINK_FAILOVER_END_EVT:
+			break;
+		case LINK_SYNCH_BEGIN_EVT:
+		case LINK_SYNCH_END_EVT:
+		default:
+			goto illegal_evt;
+		}
+		break;
+	case LINK_PEER_RESET:
+		switch (evt) {
+		case LINK_RESET_EVT:
+			l->state = LINK_ESTABLISHING;
+			break;
+		case LINK_PEER_RESET_EVT:
+		case LINK_ESTABLISH_EVT:
+		case LINK_FAILURE_EVT:
+			break;
+		case LINK_SYNCH_BEGIN_EVT:
+		case LINK_SYNCH_END_EVT:
+		case LINK_FAILOVER_BEGIN_EVT:
+		case LINK_FAILOVER_END_EVT:
+		default:
+			goto illegal_evt;
+		}
+		break;
+	case LINK_FAILINGOVER:
+		switch (evt) {
+		case LINK_FAILOVER_END_EVT:
+			l->state = LINK_RESET;
+			break;
+		case LINK_PEER_RESET_EVT:
+		case LINK_RESET_EVT:
+		case LINK_ESTABLISH_EVT:
+		case LINK_FAILURE_EVT:
+			break;
+		case LINK_FAILOVER_BEGIN_EVT:
+		case LINK_SYNCH_BEGIN_EVT:
+		case LINK_SYNCH_END_EVT:
+		default:
+			goto illegal_evt;
+		}
+		break;
+	case LINK_ESTABLISHING:
+		switch (evt) {
+		case LINK_ESTABLISH_EVT:
+			l->state = LINK_ESTABLISHED;
+			break;
+		case LINK_FAILOVER_BEGIN_EVT:
+			l->state = LINK_FAILINGOVER;
+			break;
+		case LINK_RESET_EVT:
+			l->state = LINK_RESET;
+			break;
+		case LINK_FAILURE_EVT:
+		case LINK_PEER_RESET_EVT:
+		case LINK_SYNCH_BEGIN_EVT:
+		case LINK_FAILOVER_END_EVT:
+			break;
+		case LINK_SYNCH_END_EVT:
+		default:
+			goto illegal_evt;
+		}
+		break;
+	case LINK_ESTABLISHED:
+		switch (evt) {
+		case LINK_PEER_RESET_EVT:
+			l->state = LINK_PEER_RESET;
+			rc |= TIPC_LINK_DOWN_EVT;
+			break;
+		case LINK_FAILURE_EVT:
+			l->state = LINK_RESETTING;
+			rc |= TIPC_LINK_DOWN_EVT;
+			break;
+		case LINK_RESET_EVT:
+			l->state = LINK_RESET;
+			break;
+		case LINK_ESTABLISH_EVT:
+		case LINK_SYNCH_END_EVT:
+			break;
+		case LINK_SYNCH_BEGIN_EVT:
+			l->state = LINK_SYNCHING;
+			break;
+		case LINK_FAILOVER_BEGIN_EVT:
+		case LINK_FAILOVER_END_EVT:
+		default:
+			goto illegal_evt;
+		}
+		break;
+	case LINK_SYNCHING:
+		switch (evt) {
+		case LINK_PEER_RESET_EVT:
+			l->state = LINK_PEER_RESET;
+			rc |= TIPC_LINK_DOWN_EVT;
+			break;
+		case LINK_FAILURE_EVT:
+			l->state = LINK_RESETTING;
+			rc |= TIPC_LINK_DOWN_EVT;
+			break;
+		case LINK_RESET_EVT:
+			l->state = LINK_RESET;
+			break;
+		case LINK_ESTABLISH_EVT:
+		case LINK_SYNCH_BEGIN_EVT:
+			break;
+		case LINK_SYNCH_END_EVT:
+			l->state = LINK_ESTABLISHED;
+			break;
+		case LINK_FAILOVER_BEGIN_EVT:
+		case LINK_FAILOVER_END_EVT:
+		default:
+			goto illegal_evt;
+		}
+		break;
+	default:
+		pr_err("Unknown FSM state %x in %s\n", l->state, l->name);
+	}
+	return rc;
+illegal_evt:
+	pr_err("Illegal FSM event %x in state %x on link %s\n",
+	       evt, l->state, l->name);
+	return rc;
+}
+
+/* link_profile_stats - update statistical profiling of traffic
+ */
+static void link_profile_stats(struct tipc_link *l)
+{
+	struct sk_buff *skb;
+	struct tipc_msg *msg;
+	int length;
+
+	/* Update counters used in statistical profiling of send traffic */
+	l->stats.accu_queue_sz += skb_queue_len(&l->transmq);
+	l->stats.queue_sz_counts++;
+
+	skb = skb_peek(&l->transmq);
+	if (!skb)
+		return;
+	msg = buf_msg(skb);
+	length = msg_size(msg);
+
+	if (msg_user(msg) == MSG_FRAGMENTER) {
+		if (msg_type(msg) != FIRST_FRAGMENT)
+			return;
+		length = msg_size(msg_get_wrapped(msg));
+	}
+	l->stats.msg_lengths_total += length;
+	l->stats.msg_length_counts++;
+	if (length <= 64)
+		l->stats.msg_length_profile[0]++;
+	else if (length <= 256)
+		l->stats.msg_length_profile[1]++;
+	else if (length <= 1024)
+		l->stats.msg_length_profile[2]++;
+	else if (length <= 4096)
+		l->stats.msg_length_profile[3]++;
+	else if (length <= 16384)
+		l->stats.msg_length_profile[4]++;
+	else if (length <= 32768)
+		l->stats.msg_length_profile[5]++;
+	else
+		l->stats.msg_length_profile[6]++;
+}
+
+/* tipc_link_timeout - perform periodic task as instructed from node timeout
+ */
+int tipc_link_timeout(struct tipc_link *l, struct sk_buff_head *xmitq)
+{
+	int mtyp = 0;
+	int rc = 0;
+	bool state = false;
+	bool probe = false;
+	bool setup = false;
+	u16 bc_snt = l->bc_sndlink->snd_nxt - 1;
+	u16 bc_acked = l->bc_rcvlink->acked;
+	struct tipc_mon_state *mstate = &l->mon_state;
+
+	switch (l->state) {
+	case LINK_ESTABLISHED:
+	case LINK_SYNCHING:
+		mtyp = STATE_MSG;
+		link_profile_stats(l);
+		tipc_mon_get_state(l->net, l->addr, mstate, l->bearer_id);
+		if (mstate->reset || (l->silent_intv_cnt > l->abort_limit))
+			return tipc_link_fsm_evt(l, LINK_FAILURE_EVT);
+		state = bc_acked != bc_snt;
+		state |= l->bc_rcvlink->rcv_unacked;
+		state |= l->rcv_unacked;
+		state |= !skb_queue_empty(&l->transmq);
+		state |= !skb_queue_empty(&l->deferdq);
+		probe = mstate->probing;
+		probe |= l->silent_intv_cnt;
+		if (probe || mstate->monitoring)
+			l->silent_intv_cnt++;
+		break;
+	case LINK_RESET:
+		setup = l->rst_cnt++ <= 4;
+		setup |= !(l->rst_cnt % 16);
+		mtyp = RESET_MSG;
+		break;
+	case LINK_ESTABLISHING:
+		setup = true;
+		mtyp = ACTIVATE_MSG;
+		break;
+	case LINK_PEER_RESET:
+	case LINK_RESETTING:
+	case LINK_FAILINGOVER:
+		break;
+	default:
+		break;
+	}
+
+	if (state || probe || setup)
+		tipc_link_build_proto_msg(l, mtyp, probe, 0, 0, 0, 0, xmitq);
+
+	return rc;
+}
+
+/**
+ * link_schedule_user - schedule a message sender for wakeup after congestion
+ * @l: congested link
+ * @hdr: header of message that is being sent
+ * Create pseudo msg to send back to user when congestion abates
+ */
+static int link_schedule_user(struct tipc_link *l, struct tipc_msg *hdr)
+{
+	u32 dnode = tipc_own_addr(l->net);
+	u32 dport = msg_origport(hdr);
+	struct sk_buff *skb;
+
+	/* Create and schedule wakeup pseudo message */
+	skb = tipc_msg_create(SOCK_WAKEUP, 0, INT_H_SIZE, 0,
+			      dnode, l->addr, dport, 0, 0);
+	if (!skb)
+		return -ENOBUFS;
+	msg_set_dest_droppable(buf_msg(skb), true);
+	TIPC_SKB_CB(skb)->chain_imp = msg_importance(hdr);
+	skb_queue_tail(&l->wakeupq, skb);
+	l->stats.link_congs++;
+	return -ELINKCONG;
+}
+
+/**
+ * link_prepare_wakeup - prepare users for wakeup after congestion
+ * @l: congested link
+ * Wake up a number of waiting users, as permitted by available space
+ * in the send queue
+ */
+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;
+	struct sk_buff_head tmpq;
+	int avail[5] = {0,};
+	int imp = 0;
+
+	__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 (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);
+
+	l->in_session = false;
+	l->session++;
+	l->mtu = l->advertised_mtu;
+
+	spin_lock_bh(&l->wakeupq.lock);
+	skb_queue_splice_init(&l->wakeupq, &list);
+	spin_unlock_bh(&l->wakeupq.lock);
+
+	spin_lock_bh(&l->inputq->lock);
+	skb_queue_splice_init(&list, l->inputq);
+	spin_unlock_bh(&l->inputq->lock);
+
+	__skb_queue_purge(&l->transmq);
+	__skb_queue_purge(&l->deferdq);
+	__skb_queue_purge(&l->backlogq);
+	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->failover_reasm_skb);
+	l->reasm_buf = NULL;
+	l->failover_reasm_skb = NULL;
+	l->rcv_unacked = 0;
+	l->snd_nxt = 1;
+	l->rcv_nxt = 1;
+	l->snd_nxt_state = 1;
+	l->rcv_nxt_state = 1;
+	l->acked = 0;
+	l->silent_intv_cnt = 0;
+	l->rst_cnt = 0;
+	l->stale_cnt = 0;
+	l->bc_peer_is_up = false;
+	memset(&l->mon_state, 0, sizeof(l->mon_state));
+	tipc_link_reset_stats(l);
+}
+
+/**
+ * tipc_link_xmit(): enqueue buffer list according to queue situation
+ * @link: link to use
+ * @list: chain of buffers containing message
+ * @xmitq: returned list of packets to be sent by caller
+ *
+ * Consumes the buffer chain.
+ * Returns 0 if success, or errno: -ELINKCONG, -EMSGSIZE or -ENOBUFS
+ * Messages at TIPC_SYSTEM_IMPORTANCE are always accepted
+ */
+int tipc_link_xmit(struct tipc_link *l, struct sk_buff_head *list,
+		   struct sk_buff_head *xmitq)
+{
+	unsigned int maxwin = l->window;
+	unsigned int mtu = l->mtu;
+	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, **tskb;
+	int pkt_cnt = skb_queue_len(list);
+	struct tipc_msg *hdr;
+	int rc = 0;
+	int imp;
+
+	if (pkt_cnt <= 0)
+		return 0;
+
+	hdr = buf_msg(skb_peek(list));
+	if (unlikely(msg_size(hdr) > mtu)) {
+		__skb_queue_purge(list);
+		return -EMSGSIZE;
+	}
+
+	imp = msg_importance(hdr);
+	/* Allow oversubscription of one data msg per source at congestion */
+	if (unlikely(l->backlog[imp].len >= l->backlog[imp].limit)) {
+		if (imp == TIPC_SYSTEM_IMPORTANCE) {
+			pr_warn("%s<%s>, link overflow", link_rst_msg, l->name);
+			return -ENOBUFS;
+		}
+		rc = link_schedule_user(l, hdr);
+	}
+
+	if (pkt_cnt > 1) {
+		l->stats.sent_fragmented++;
+		l->stats.sent_fragments += pkt_cnt;
+	}
+
+	/* 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)) {
+			_skb = skb_clone(skb, GFP_ATOMIC);
+			if (!_skb) {
+				__skb_queue_purge(list);
+				return -ENOBUFS;
+			}
+			__skb_dequeue(list);
+			__skb_queue_tail(transmq, skb);
+			__skb_queue_tail(xmitq, _skb);
+			TIPC_SKB_CB(skb)->ackers = l->ackers;
+			l->rcv_unacked = 0;
+			l->stats.sent_pkts++;
+			seqno++;
+			continue;
+		}
+		tskb = &l->backlog[imp].target_bskb;
+		if (tipc_msg_bundle(*tskb, hdr, mtu)) {
+			kfree_skb(__skb_dequeue(list));
+			l->stats.sent_bundled++;
+			continue;
+		}
+		if (tipc_msg_make_bundle(tskb, hdr, mtu, l->addr)) {
+			kfree_skb(__skb_dequeue(list));
+			__skb_queue_tail(backlogq, *tskb);
+			l->backlog[imp].len++;
+			l->stats.sent_bundled++;
+			l->stats.sent_bundles++;
+			continue;
+		}
+		l->backlog[imp].target_bskb = NULL;
+		l->backlog[imp].len += skb_queue_len(list);
+		skb_queue_splice_tail_init(list, backlogq);
+	}
+	l->snd_nxt = seqno;
+	return rc;
+}
+
+static void tipc_link_advance_backlog(struct tipc_link *l,
+				      struct sk_buff_head *xmitq)
+{
+	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;
+	u32 imp;
+
+	while (skb_queue_len(&l->transmq) < l->window) {
+		skb = skb_peek(&l->backlogq);
+		if (!skb)
+			break;
+		_skb = skb_clone(skb, GFP_ATOMIC);
+		if (!_skb)
+			break;
+		__skb_dequeue(&l->backlogq);
+		hdr = buf_msg(skb);
+		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);
+		__skb_queue_tail(xmitq, _skb);
+		TIPC_SKB_CB(skb)->ackers = l->ackers;
+		msg_set_seqno(hdr, seqno);
+		msg_set_ack(hdr, ack);
+		msg_set_bcast_ack(hdr, bc_ack);
+		l->rcv_unacked = 0;
+		l->stats.sent_pkts++;
+		seqno++;
+	}
+	l->snd_nxt = seqno;
+}
+
+static void link_retransmit_failure(struct tipc_link *l, struct sk_buff *skb)
+{
+	struct tipc_msg *hdr = buf_msg(skb);
+
+	pr_warn("Retransmission failure on link <%s>\n", l->name);
+	link_print(l, "State of link ");
+	pr_info("Failed msg: usr %u, typ %u, len %u, err %u\n",
+		msg_user(hdr), msg_type(hdr), msg_size(hdr), msg_errcode(hdr));
+	pr_info("sqno %u, prev: %x, src: %x\n",
+		msg_seqno(hdr), msg_prevnode(hdr), msg_orignode(hdr));
+}
+
+/* tipc_link_retrans() - retransmit one or more packets
+ * @l: the link to transmit on
+ * @r: the receiving link ordering the retransmit. Same as l if unicast
+ * @from: retransmit from (inclusive) this sequence number
+ * @to: retransmit to (inclusive) this sequence number
+ * xmitq: queue for accumulating the retransmitted packets
+ */
+static int tipc_link_retrans(struct tipc_link *l, struct tipc_link *r,
+			     u16 from, u16 to, struct sk_buff_head *xmitq)
+{
+	struct sk_buff *_skb, *skb = skb_peek(&l->transmq);
+	u16 bc_ack = l->bc_rcvlink->rcv_nxt - 1;
+	u16 ack = l->rcv_nxt - 1;
+	struct tipc_msg *hdr;
+
+	if (!skb)
+		return 0;
+
+	/* Detect repeated retransmit failures on same packet */
+	if (r->last_retransm != buf_seqno(skb)) {
+		r->last_retransm = buf_seqno(skb);
+		r->stale_limit = jiffies + msecs_to_jiffies(r->tolerance);
+		r->stale_cnt = 0;
+	} else if (++r->stale_cnt > 99 && time_after(jiffies, r->stale_limit)) {
+		link_retransmit_failure(l, skb);
+		if (link_is_bc_sndlink(l))
+			return TIPC_LINK_DOWN_EVT;
+		return tipc_link_fsm_evt(l, LINK_FAILURE_EVT);
+	}
+
+	skb_queue_walk(&l->transmq, skb) {
+		hdr = buf_msg(skb);
+		if (less(msg_seqno(hdr), from))
+			continue;
+		if (more(msg_seqno(hdr), to))
+			break;
+		_skb = __pskb_copy(skb, MIN_H_SIZE, GFP_ATOMIC);
+		if (!_skb)
+			return 0;
+		hdr = buf_msg(_skb);
+		msg_set_ack(hdr, ack);
+		msg_set_bcast_ack(hdr, bc_ack);
+		_skb->priority = TC_PRIO_CONTROL;
+		__skb_queue_tail(xmitq, _skb);
+		l->stats.retransmitted++;
+	}
+	return 0;
+}
+
+/* tipc_data_input - deliver data and name distr msgs to upper layer
+ *
+ * Consumes buffer if message is of right type
+ * Node lock must be held
+ */
+static bool tipc_data_input(struct tipc_link *l, struct sk_buff *skb,
+			    struct sk_buff_head *inputq)
+{
+	struct sk_buff_head *mc_inputq = l->bc_rcvlink->inputq;
+	struct tipc_msg *hdr = buf_msg(skb);
+
+	switch (msg_user(hdr)) {
+	case TIPC_LOW_IMPORTANCE:
+	case TIPC_MEDIUM_IMPORTANCE:
+	case TIPC_HIGH_IMPORTANCE:
+	case TIPC_CRITICAL_IMPORTANCE:
+		if (unlikely(msg_in_group(hdr) || msg_mcast(hdr))) {
+			skb_queue_tail(mc_inputq, skb);
+			return true;
+		}
+		/* else: fall through */
+	case CONN_MANAGER:
+		skb_queue_tail(inputq, skb);
+		return true;
+	case GROUP_PROTOCOL:
+		skb_queue_tail(mc_inputq, skb);
+		return true;
+	case NAME_DISTRIBUTOR:
+		l->bc_rcvlink->state = LINK_ESTABLISHED;
+		skb_queue_tail(l->namedq, skb);
+		return true;
+	case MSG_BUNDLER:
+	case TUNNEL_PROTOCOL:
+	case MSG_FRAGMENTER:
+	case BCAST_PROTOCOL:
+		return false;
+	default:
+		pr_warn("Dropping received illegal msg type\n");
+		kfree_skb(skb);
+		return true;
+	};
+}
+
+/* tipc_link_input - process packet that has passed link protocol check
+ *
+ * Consumes buffer
+ */
+static int tipc_link_input(struct tipc_link *l, struct sk_buff *skb,
+			   struct sk_buff_head *inputq)
+{
+	struct tipc_msg *hdr = buf_msg(skb);
+	struct sk_buff **reasm_skb = &l->reasm_buf;
+	struct sk_buff *iskb;
+	struct sk_buff_head tmpq;
+	int usr = msg_user(hdr);
+	int rc = 0;
+	int pos = 0;
+	int ipos = 0;
+
+	if (unlikely(usr == TUNNEL_PROTOCOL)) {
+		if (msg_type(hdr) == SYNCH_MSG) {
+			__skb_queue_purge(&l->deferdq);
+			goto drop;
+		}
+		if (!tipc_msg_extract(skb, &iskb, &ipos))
+			return rc;
+		kfree_skb(skb);
+		skb = iskb;
+		hdr = buf_msg(skb);
+		if (less(msg_seqno(hdr), l->drop_point))
+			goto drop;
+		if (tipc_data_input(l, skb, inputq))
+			return rc;
+		usr = msg_user(hdr);
+		reasm_skb = &l->failover_reasm_skb;
+	}
+
+	if (usr == MSG_BUNDLER) {
+		skb_queue_head_init(&tmpq);
+		l->stats.recv_bundles++;
+		l->stats.recv_bundled += msg_msgcnt(hdr);
+		while (tipc_msg_extract(skb, &iskb, &pos))
+			tipc_data_input(l, iskb, &tmpq);
+		tipc_skb_queue_splice_tail(&tmpq, inputq);
+		return 0;
+	} else if (usr == MSG_FRAGMENTER) {
+		l->stats.recv_fragments++;
+		if (tipc_buf_append(reasm_skb, &skb)) {
+			l->stats.recv_fragmented++;
+			tipc_data_input(l, skb, inputq);
+		} else if (!*reasm_skb && !link_is_bc_rcvlink(l)) {
+			pr_warn_ratelimited("Unable to build fragment list\n");
+			return tipc_link_fsm_evt(l, LINK_FAILURE_EVT);
+		}
+		return 0;
+	} else if (usr == BCAST_PROTOCOL) {
+		tipc_bcast_lock(l->net);
+		tipc_link_bc_init_rcv(l->bc_rcvlink, hdr);
+		tipc_bcast_unlock(l->net);
+	}
+drop:
+	kfree_skb(skb);
+	return 0;
+}
+
+static bool tipc_link_release_pkts(struct tipc_link *l, u16 acked)
+{
+	bool released = false;
+	struct sk_buff *skb, *tmp;
+
+	skb_queue_walk_safe(&l->transmq, skb, tmp) {
+		if (more(buf_seqno(skb), acked))
+			break;
+		__skb_unlink(skb, &l->transmq);
+		kfree_skb(skb);
+		released = true;
+	}
+	return released;
+}
+
+/* tipc_link_build_state_msg: prepare link state message for transmission
+ *
+ * Note that sending of broadcast ack is coordinated among nodes, to reduce
+ * risk of ack storms towards the sender
+ */
+int tipc_link_build_state_msg(struct tipc_link *l, struct sk_buff_head *xmitq)
+{
+	if (!l)
+		return 0;
+
+	/* Broadcast ACK must be sent via a unicast link => defer to caller */
+	if (link_is_bc_rcvlink(l)) {
+		if (((l->rcv_nxt ^ tipc_own_addr(l->net)) & 0xf) != 0xf)
+			return 0;
+		l->rcv_unacked = 0;
+
+		/* Use snd_nxt to store peer's snd_nxt in broadcast rcv link */
+		l->snd_nxt = l->rcv_nxt;
+		return TIPC_LINK_SND_STATE;
+	}
+
+	/* Unicast ACK */
+	l->rcv_unacked = 0;
+	l->stats.sent_acks++;
+	tipc_link_build_proto_msg(l, STATE_MSG, 0, 0, 0, 0, 0, xmitq);
+	return 0;
+}
+
+/* tipc_link_build_reset_msg: prepare link RESET or ACTIVATE message
+ */
+void tipc_link_build_reset_msg(struct tipc_link *l, struct sk_buff_head *xmitq)
+{
+	int mtyp = RESET_MSG;
+	struct sk_buff *skb;
+
+	if (l->state == LINK_ESTABLISHING)
+		mtyp = ACTIVATE_MSG;
+
+	tipc_link_build_proto_msg(l, mtyp, 0, 0, 0, 0, 0, xmitq);
+
+	/* Inform peer that this endpoint is going down if applicable */
+	skb = skb_peek_tail(xmitq);
+	if (skb && (l->state == LINK_RESET))
+		msg_set_peer_stopping(buf_msg(skb), 1);
+}
+
+/* tipc_link_build_nack_msg: prepare link nack message for transmission
+ * Note that sending of broadcast NACK is coordinated among nodes, to
+ * reduce the risk of NACK storms towards the sender
+ */
+static int tipc_link_build_nack_msg(struct tipc_link *l,
+				    struct sk_buff_head *xmitq)
+{
+	u32 def_cnt = ++l->stats.deferred_recv;
+	int match1, match2;
+
+	if (link_is_bc_rcvlink(l)) {
+		match1 = def_cnt & 0xf;
+		match2 = tipc_own_addr(l->net) & 0xf;
+		if (match1 == match2)
+			return TIPC_LINK_SND_STATE;
+		return 0;
+	}
+
+	if ((skb_queue_len(&l->deferdq) == 1) || !(def_cnt % TIPC_NACK_INTV))
+		tipc_link_build_proto_msg(l, STATE_MSG, 0, 0, 0, 0, 0, xmitq);
+	return 0;
+}
+
+/* tipc_link_rcv - process TIPC packets/messages arriving from off-node
+ * @l: the link that should handle the message
+ * @skb: TIPC packet
+ * @xmitq: queue to place packets to be sent after this call
+ */
+int tipc_link_rcv(struct tipc_link *l, struct sk_buff *skb,
+		  struct sk_buff_head *xmitq)
+{
+	struct sk_buff_head *defq = &l->deferdq;
+	struct tipc_msg *hdr;
+	u16 seqno, rcv_nxt, win_lim;
+	int rc = 0;
+
+	do {
+		hdr = buf_msg(skb);
+		seqno = msg_seqno(hdr);
+		rcv_nxt = l->rcv_nxt;
+		win_lim = rcv_nxt + TIPC_MAX_LINK_WIN;
+
+		/* Verify and update link state */
+		if (unlikely(msg_user(hdr) == LINK_PROTOCOL))
+			return tipc_link_proto_rcv(l, skb, xmitq);
+
+		if (unlikely(!link_is_up(l))) {
+			if (l->state == LINK_ESTABLISHING)
+				rc = TIPC_LINK_UP_EVT;
+			goto drop;
+		}
+
+		/* Don't send probe at next timeout expiration */
+		l->silent_intv_cnt = 0;
+
+		/* 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)))) {
+			l->stale_cnt = 0;
+			tipc_link_advance_backlog(l, xmitq);
+			if (unlikely(!skb_queue_empty(&l->wakeupq)))
+				link_prepare_wakeup(l);
+		}
+
+		/* Defer delivery if sequence gap */
+		if (unlikely(seqno != rcv_nxt)) {
+			__tipc_skb_queue_sorted(defq, seqno, skb);
+			rc |= tipc_link_build_nack_msg(l, xmitq);
+			break;
+		}
+
+		/* Deliver packet */
+		l->rcv_nxt++;
+		l->stats.recv_pkts++;
+		if (!tipc_data_input(l, skb, l->inputq))
+			rc |= tipc_link_input(l, skb, l->inputq);
+		if (unlikely(++l->rcv_unacked >= TIPC_MIN_LINK_WIN))
+			rc |= tipc_link_build_state_msg(l, xmitq);
+		if (unlikely(rc & ~TIPC_LINK_SND_STATE))
+			break;
+	} while ((skb = __skb_dequeue(defq)));
+
+	return rc;
+drop:
+	kfree_skb(skb);
+	return rc;
+}
+
+static void tipc_link_build_proto_msg(struct tipc_link *l, int mtyp, bool probe,
+				      bool probe_reply, u16 rcvgap,
+				      int tolerance, int priority,
+				      struct sk_buff_head *xmitq)
+{
+	struct tipc_link *bcl = l->bc_rcvlink;
+	struct sk_buff *skb;
+	struct tipc_msg *hdr;
+	struct sk_buff_head *dfq = &l->deferdq;
+	bool node_up = link_is_up(bcl);
+	struct tipc_mon_state *mstate = &l->mon_state;
+	int dlen = 0;
+	void *data;
+
+	/* Don't send protocol message during reset or link failover */
+	if (tipc_link_is_blocked(l))
+		return;
+
+	if (!tipc_link_is_up(l) && (mtyp == STATE_MSG))
+		return;
+
+	if (!skb_queue_empty(dfq))
+		rcvgap = buf_seqno(skb_peek(dfq)) - l->rcv_nxt;
+
+	skb = tipc_msg_create(LINK_PROTOCOL, mtyp, INT_H_SIZE,
+			      tipc_max_domain_size, l->addr,
+			      tipc_own_addr(l->net), 0, 0, 0);
+	if (!skb)
+		return;
+
+	hdr = buf_msg(skb);
+	data = msg_data(hdr);
+	msg_set_session(hdr, l->session);
+	msg_set_bearer_id(hdr, l->bearer_id);
+	msg_set_net_plane(hdr, l->net_plane);
+	msg_set_next_sent(hdr, l->snd_nxt);
+	msg_set_ack(hdr, l->rcv_nxt - 1);
+	msg_set_bcast_ack(hdr, bcl->rcv_nxt - 1);
+	msg_set_bc_ack_invalid(hdr, !node_up);
+	msg_set_last_bcast(hdr, l->bc_sndlink->snd_nxt - 1);
+	msg_set_link_tolerance(hdr, tolerance);
+	msg_set_linkprio(hdr, priority);
+	msg_set_redundant_link(hdr, node_up);
+	msg_set_seq_gap(hdr, 0);
+	msg_set_seqno(hdr, l->snd_nxt + U16_MAX / 2);
+
+	if (mtyp == STATE_MSG) {
+		if (l->peer_caps & TIPC_LINK_PROTO_SEQNO)
+			msg_set_seqno(hdr, l->snd_nxt_state++);
+		msg_set_seq_gap(hdr, rcvgap);
+		msg_set_bc_gap(hdr, link_bc_rcv_gap(bcl));
+		msg_set_probe(hdr, probe);
+		msg_set_is_keepalive(hdr, probe || probe_reply);
+		tipc_mon_prep(l->net, data, &dlen, mstate, l->bearer_id);
+		msg_set_size(hdr, INT_H_SIZE + dlen);
+		skb_trim(skb, INT_H_SIZE + dlen);
+		l->stats.sent_states++;
+		l->rcv_unacked = 0;
+	} else {
+		/* RESET_MSG or ACTIVATE_MSG */
+		msg_set_max_pkt(hdr, l->advertised_mtu);
+		strcpy(data, l->if_name);
+		msg_set_size(hdr, INT_H_SIZE + TIPC_MAX_IF_NAME);
+		skb_trim(skb, INT_H_SIZE + TIPC_MAX_IF_NAME);
+	}
+	if (probe)
+		l->stats.sent_probes++;
+	if (rcvgap)
+		l->stats.sent_nacks++;
+	skb->priority = TC_PRIO_CONTROL;
+	__skb_queue_tail(xmitq, skb);
+}
+
+void tipc_link_create_dummy_tnl_msg(struct tipc_link *l,
+				    struct sk_buff_head *xmitq)
+{
+	u32 onode = tipc_own_addr(l->net);
+	struct tipc_msg *hdr, *ihdr;
+	struct sk_buff_head tnlq;
+	struct sk_buff *skb;
+	u32 dnode = l->addr;
+
+	__skb_queue_head_init(&tnlq);
+	skb = tipc_msg_create(TUNNEL_PROTOCOL, FAILOVER_MSG,
+			      INT_H_SIZE, BASIC_H_SIZE,
+			      dnode, onode, 0, 0, 0);
+	if (!skb) {
+		pr_warn("%sunable to create tunnel packet\n", link_co_err);
+		return;
+	}
+
+	hdr = buf_msg(skb);
+	msg_set_msgcnt(hdr, 1);
+	msg_set_bearer_id(hdr, l->peer_bearer_id);
+
+	ihdr = (struct tipc_msg *)msg_data(hdr);
+	tipc_msg_init(onode, ihdr, TIPC_LOW_IMPORTANCE, TIPC_DIRECT_MSG,
+		      BASIC_H_SIZE, dnode);
+	msg_set_errcode(ihdr, TIPC_ERR_NO_PORT);
+	__skb_queue_tail(&tnlq, skb);
+	tipc_link_xmit(l, &tnlq, xmitq);
+}
+
+/* tipc_link_tnl_prepare(): prepare and return a list of tunnel packets
+ * with contents of the link's transmit and backlog queues.
+ */
+void tipc_link_tnl_prepare(struct tipc_link *l, struct tipc_link *tnl,
+			   int mtyp, struct sk_buff_head *xmitq)
+{
+	struct sk_buff *skb, *tnlskb;
+	struct tipc_msg *hdr, tnlhdr;
+	struct sk_buff_head *queue = &l->transmq;
+	struct sk_buff_head tmpxq, tnlq;
+	u16 pktlen, pktcnt, seqno = l->snd_nxt;
+
+	if (!tnl)
+		return;
+
+	__skb_queue_head_init(&tnlq);
+	__skb_queue_head_init(&tmpxq);
+
+	/* 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),
+			      0, 0, TIPC_ERR_NO_PORT);
+	if (!skb) {
+		pr_warn("%sunable to create tunnel packet\n", link_co_err);
+		return;
+	}
+	__skb_queue_tail(&tnlq, skb);
+	tipc_link_xmit(l, &tnlq, &tmpxq);
+	__skb_queue_purge(&tmpxq);
+
+	/* Initialize reusable tunnel packet header */
+	tipc_msg_init(tipc_own_addr(l->net), &tnlhdr, TUNNEL_PROTOCOL,
+		      mtyp, INT_H_SIZE, l->addr);
+	pktcnt = skb_queue_len(&l->transmq) + skb_queue_len(&l->backlogq);
+	msg_set_msgcnt(&tnlhdr, pktcnt);
+	msg_set_bearer_id(&tnlhdr, l->peer_bearer_id);
+tnl:
+	/* Wrap each packet into a tunnel packet */
+	skb_queue_walk(queue, skb) {
+		hdr = buf_msg(skb);
+		if (queue == &l->backlogq)
+			msg_set_seqno(hdr, seqno++);
+		pktlen = msg_size(hdr);
+		msg_set_size(&tnlhdr, pktlen + INT_H_SIZE);
+		tnlskb = tipc_buf_acquire(pktlen + INT_H_SIZE, GFP_ATOMIC);
+		if (!tnlskb) {
+			pr_warn("%sunable to send packet\n", link_co_err);
+			return;
+		}
+		skb_copy_to_linear_data(tnlskb, &tnlhdr, INT_H_SIZE);
+		skb_copy_to_linear_data_offset(tnlskb, INT_H_SIZE, hdr, pktlen);
+		__skb_queue_tail(&tnlq, tnlskb);
+	}
+	if (queue != &l->backlogq) {
+		queue = &l->backlogq;
+		goto tnl;
+	}
+
+	tipc_link_xmit(tnl, &tnlq, xmitq);
+
+	if (mtyp == FAILOVER_MSG) {
+		tnl->drop_point = l->rcv_nxt;
+		tnl->failover_reasm_skb = l->reasm_buf;
+		l->reasm_buf = NULL;
+	}
+}
+
+/* tipc_link_validate_msg(): validate message against current link state
+ * Returns true if message should be accepted, otherwise false
+ */
+bool tipc_link_validate_msg(struct tipc_link *l, struct tipc_msg *hdr)
+{
+	u16 curr_session = l->peer_session;
+	u16 session = msg_session(hdr);
+	int mtyp = msg_type(hdr);
+
+	if (msg_user(hdr) != LINK_PROTOCOL)
+		return true;
+
+	switch (mtyp) {
+	case RESET_MSG:
+		if (!l->in_session)
+			return true;
+		/* Accept only RESET with new session number */
+		return more(session, curr_session);
+	case ACTIVATE_MSG:
+		if (!l->in_session)
+			return true;
+		/* Accept only ACTIVATE with new or current session number */
+		return !less(session, curr_session);
+	case STATE_MSG:
+		/* Accept only STATE with current session number */
+		if (!l->in_session)
+			return false;
+		if (session != curr_session)
+			return false;
+		/* Extra sanity check */
+		if (!link_is_up(l) && msg_ack(hdr))
+			return false;
+		if (!(l->peer_caps & TIPC_LINK_PROTO_SEQNO))
+			return true;
+		/* Accept only STATE with new sequence number */
+		return !less(msg_seqno(hdr), l->rcv_nxt_state);
+	default:
+		return false;
+	}
+}
+
+/* tipc_link_proto_rcv(): receive link level protocol message :
+ * Note that network plane id propagates through the network, and may
+ * change at any time. The node with lowest numerical id determines
+ * network plane
+ */
+static int tipc_link_proto_rcv(struct tipc_link *l, struct sk_buff *skb,
+			       struct sk_buff_head *xmitq)
+{
+	struct tipc_msg *hdr = buf_msg(skb);
+	u16 rcvgap = 0;
+	u16 ack = msg_ack(hdr);
+	u16 gap = msg_seq_gap(hdr);
+	u16 peers_snd_nxt =  msg_next_sent(hdr);
+	u16 peers_tol = msg_link_tolerance(hdr);
+	u16 peers_prio = msg_linkprio(hdr);
+	u16 rcv_nxt = l->rcv_nxt;
+	u32 dlen = msg_data_sz(hdr);
+	int mtyp = msg_type(hdr);
+	bool reply = msg_probe(hdr);
+	void *data;
+	char *if_name;
+	int rc = 0;
+
+	if (dlen > U16_MAX)
+		goto exit;
+
+	if (tipc_link_is_blocked(l) || !xmitq)
+		goto exit;
+
+	if (tipc_own_addr(l->net) > msg_prevnode(hdr))
+		l->net_plane = msg_net_plane(hdr);
+
+	skb_linearize(skb);
+	hdr = buf_msg(skb);
+	data = msg_data(hdr);
+
+	if (!tipc_link_validate_msg(l, hdr))
+		goto exit;
+
+	switch (mtyp) {
+	case RESET_MSG:
+	case ACTIVATE_MSG:
+		/* Complete own link name with peer's interface name */
+		if_name =  strrchr(l->name, ':') + 1;
+		if (sizeof(l->name) - (if_name - l->name) <= TIPC_MAX_IF_NAME)
+			break;
+		if (msg_data_sz(hdr) < TIPC_MAX_IF_NAME)
+			break;
+		strncpy(if_name, data, TIPC_MAX_IF_NAME);
+
+		/* Update own tolerance if peer indicates a non-zero value */
+		if (in_range(peers_tol, TIPC_MIN_LINK_TOL, TIPC_MAX_LINK_TOL)) {
+			l->tolerance = peers_tol;
+			l->bc_rcvlink->tolerance = peers_tol;
+		}
+		/* Update own priority if peer's priority is higher */
+		if (in_range(peers_prio, l->priority + 1, TIPC_MAX_LINK_PRI))
+			l->priority = peers_prio;
+
+		/* If peer is going down we want full re-establish cycle */
+		if (msg_peer_stopping(hdr)) {
+			rc = tipc_link_fsm_evt(l, LINK_FAILURE_EVT);
+			break;
+		}
+		/* ACTIVATE_MSG serves as PEER_RESET if link is already down */
+		if (mtyp == RESET_MSG || !link_is_up(l))
+			rc = tipc_link_fsm_evt(l, LINK_PEER_RESET_EVT);
+
+		/* ACTIVATE_MSG takes up link if it was already locally reset */
+		if (mtyp == ACTIVATE_MSG && l->state == LINK_ESTABLISHING)
+			rc = TIPC_LINK_UP_EVT;
+
+		l->peer_session = msg_session(hdr);
+		l->in_session = true;
+		l->peer_bearer_id = msg_bearer_id(hdr);
+		if (l->mtu > msg_max_pkt(hdr))
+			l->mtu = msg_max_pkt(hdr);
+		break;
+
+	case STATE_MSG:
+		l->rcv_nxt_state = msg_seqno(hdr) + 1;
+
+		/* Update own tolerance if peer indicates a non-zero value */
+		if (in_range(peers_tol, TIPC_MIN_LINK_TOL, TIPC_MAX_LINK_TOL)) {
+			l->tolerance = peers_tol;
+			l->bc_rcvlink->tolerance = peers_tol;
+		}
+		/* Update own prio if peer indicates a different value */
+		if ((peers_prio != l->priority) &&
+		    in_range(peers_prio, 1, TIPC_MAX_LINK_PRI)) {
+			l->priority = peers_prio;
+			rc = tipc_link_fsm_evt(l, LINK_FAILURE_EVT);
+		}
+
+		l->silent_intv_cnt = 0;
+		l->stats.recv_states++;
+		if (msg_probe(hdr))
+			l->stats.recv_probes++;
+
+		if (!link_is_up(l)) {
+			if (l->state == LINK_ESTABLISHING)
+				rc = TIPC_LINK_UP_EVT;
+			break;
+		}
+		tipc_mon_rcv(l->net, data, dlen, l->addr,
+			     &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))
+			rcvgap = peers_snd_nxt - l->rcv_nxt;
+		if (rcvgap || reply)
+			tipc_link_build_proto_msg(l, STATE_MSG, 0, reply,
+						  rcvgap, 0, 0, xmitq);
+		tipc_link_release_pkts(l, ack);
+
+		/* If NACK, retransmit will now start at right position */
+		if (gap) {
+			rc = tipc_link_retrans(l, l, ack + 1, ack + gap, xmitq);
+			l->stats.recv_nacks++;
+		}
+
+		tipc_link_advance_backlog(l, xmitq);
+		if (unlikely(!skb_queue_empty(&l->wakeupq)))
+			link_prepare_wakeup(l);
+	}
+exit:
+	kfree_skb(skb);
+	return rc;
+}
+
+/* tipc_link_build_bc_proto_msg() - create broadcast protocol message
+ */
+static bool tipc_link_build_bc_proto_msg(struct tipc_link *l, bool bcast,
+					 u16 peers_snd_nxt,
+					 struct sk_buff_head *xmitq)
+{
+	struct sk_buff *skb;
+	struct tipc_msg *hdr;
+	struct sk_buff *dfrd_skb = skb_peek(&l->deferdq);
+	u16 ack = l->rcv_nxt - 1;
+	u16 gap_to = peers_snd_nxt - 1;
+
+	skb = tipc_msg_create(BCAST_PROTOCOL, STATE_MSG, INT_H_SIZE,
+			      0, l->addr, tipc_own_addr(l->net), 0, 0, 0);
+	if (!skb)
+		return false;
+	hdr = buf_msg(skb);
+	msg_set_last_bcast(hdr, l->bc_sndlink->snd_nxt - 1);
+	msg_set_bcast_ack(hdr, ack);
+	msg_set_bcgap_after(hdr, ack);
+	if (dfrd_skb)
+		gap_to = buf_seqno(dfrd_skb) - 1;
+	msg_set_bcgap_to(hdr, gap_to);
+	msg_set_non_seq(hdr, bcast);
+	__skb_queue_tail(xmitq, skb);
+	return true;
+}
+
+/* tipc_link_build_bc_init_msg() - synchronize broadcast link endpoints.
+ *
+ * Give a newly added peer node the sequence number where it should
+ * start receiving and acking broadcast packets.
+ */
+static void tipc_link_build_bc_init_msg(struct tipc_link *l,
+					struct sk_buff_head *xmitq)
+{
+	struct sk_buff_head list;
+
+	__skb_queue_head_init(&list);
+	if (!tipc_link_build_bc_proto_msg(l->bc_rcvlink, false, 0, &list))
+		return;
+	msg_set_bc_ack_invalid(buf_msg(skb_peek(&list)), true);
+	tipc_link_xmit(l, &list, xmitq);
+}
+
+/* tipc_link_bc_init_rcv - receive initial broadcast synch data from peer
+ */
+void tipc_link_bc_init_rcv(struct tipc_link *l, struct tipc_msg *hdr)
+{
+	int mtyp = msg_type(hdr);
+	u16 peers_snd_nxt = msg_bc_snd_nxt(hdr);
+
+	if (link_is_up(l))
+		return;
+
+	if (msg_user(hdr) == BCAST_PROTOCOL) {
+		l->rcv_nxt = peers_snd_nxt;
+		l->state = LINK_ESTABLISHED;
+		return;
+	}
+
+	if (l->peer_caps & TIPC_BCAST_SYNCH)
+		return;
+
+	if (msg_peer_node_is_up(hdr))
+		return;
+
+	/* Compatibility: accept older, less safe initial synch data */
+	if ((mtyp == RESET_MSG) || (mtyp == ACTIVATE_MSG))
+		l->rcv_nxt = peers_snd_nxt;
+}
+
+/* link_bc_retr eval()- check if the indicated range can be retransmitted now
+ * - Adjust permitted range if there is overlap with previous retransmission
+ */
+static bool link_bc_retr_eval(struct tipc_link *l, u16 *from, u16 *to)
+{
+	unsigned long elapsed = jiffies_to_msecs(jiffies - l->prev_retr);
+
+	if (less(*to, *from))
+		return false;
+
+	/* New retransmission request */
+	if ((elapsed > TIPC_BC_RETR_LIMIT) ||
+	    less(*to, l->prev_from) || more(*from, l->prev_to)) {
+		l->prev_from = *from;
+		l->prev_to = *to;
+		l->prev_retr = jiffies;
+		return true;
+	}
+
+	/* Inside range of previous retransmit */
+	if (!less(*from, l->prev_from) && !more(*to, l->prev_to))
+		return false;
+
+	/* Fully or partially outside previous range => exclude overlap */
+	if (less(*from, l->prev_from)) {
+		*to = l->prev_from - 1;
+		l->prev_from = *from;
+	}
+	if (more(*to, l->prev_to)) {
+		*from = l->prev_to + 1;
+		l->prev_to = *to;
+	}
+	l->prev_retr = jiffies;
+	return true;
+}
+
+/* tipc_link_bc_sync_rcv - update rcv link according to peer's send state
+ */
+int tipc_link_bc_sync_rcv(struct tipc_link *l, struct tipc_msg *hdr,
+			  struct sk_buff_head *xmitq)
+{
+	struct tipc_link *snd_l = l->bc_sndlink;
+	u16 peers_snd_nxt = msg_bc_snd_nxt(hdr);
+	u16 from = msg_bcast_ack(hdr) + 1;
+	u16 to = from + msg_bc_gap(hdr) - 1;
+	int rc = 0;
+
+	if (!link_is_up(l))
+		return rc;
+
+	if (!msg_peer_node_is_up(hdr))
+		return rc;
+
+	/* Open when peer ackowledges our bcast init msg (pkt #1) */
+	if (msg_ack(hdr))
+		l->bc_peer_is_up = true;
+
+	if (!l->bc_peer_is_up)
+		return rc;
+
+	l->stats.recv_nacks++;
+
+	/* Ignore if peers_snd_nxt goes beyond receive window */
+	if (more(peers_snd_nxt, l->rcv_nxt + l->window))
+		return rc;
+
+	if (link_bc_retr_eval(snd_l, &from, &to))
+		rc = tipc_link_retrans(snd_l, l, from, to, xmitq);
+
+	l->snd_nxt = peers_snd_nxt;
+	if (link_bc_rcv_gap(l))
+		rc |= TIPC_LINK_SND_STATE;
+
+	/* Return now if sender supports nack via STATE messages */
+	if (l->peer_caps & TIPC_BCAST_STATE_NACK)
+		return rc;
+
+	/* Otherwise, be backwards compatible */
+
+	if (!more(peers_snd_nxt, l->rcv_nxt)) {
+		l->nack_state = BC_NACK_SND_CONDITIONAL;
+		return 0;
+	}
+
+	/* Don't NACK if one was recently sent or peeked */
+	if (l->nack_state == BC_NACK_SND_SUPPRESS) {
+		l->nack_state = BC_NACK_SND_UNCONDITIONAL;
+		return 0;
+	}
+
+	/* Conditionally delay NACK sending until next synch rcv */
+	if (l->nack_state == BC_NACK_SND_CONDITIONAL) {
+		l->nack_state = BC_NACK_SND_UNCONDITIONAL;
+		if ((peers_snd_nxt - l->rcv_nxt) < TIPC_MIN_LINK_WIN)
+			return 0;
+	}
+
+	/* Send NACK now but suppress next one */
+	tipc_link_build_bc_proto_msg(l, true, peers_snd_nxt, xmitq);
+	l->nack_state = BC_NACK_SND_SUPPRESS;
+	return 0;
+}
+
+void tipc_link_bc_ack_rcv(struct tipc_link *l, u16 acked,
+			  struct sk_buff_head *xmitq)
+{
+	struct sk_buff *skb, *tmp;
+	struct tipc_link *snd_l = l->bc_sndlink;
+
+	if (!link_is_up(l) || !l->bc_peer_is_up)
+		return;
+
+	if (!more(acked, l->acked))
+		return;
+
+	/* Skip over packets peer has already acked */
+	skb_queue_walk(&snd_l->transmq, skb) {
+		if (more(buf_seqno(skb), l->acked))
+			break;
+	}
+
+	/* Update/release the packets peer is acking now */
+	skb_queue_walk_from_safe(&snd_l->transmq, skb, tmp) {
+		if (more(buf_seqno(skb), acked))
+			break;
+		if (!--TIPC_SKB_CB(skb)->ackers) {
+			__skb_unlink(skb, &snd_l->transmq);
+			kfree_skb(skb);
+		}
+	}
+	l->acked = acked;
+	tipc_link_advance_backlog(snd_l, xmitq);
+	if (unlikely(!skb_queue_empty(&snd_l->wakeupq)))
+		link_prepare_wakeup(snd_l);
+}
+
+/* tipc_link_bc_nack_rcv(): receive broadcast nack message
+ * This function is here for backwards compatibility, since
+ * no BCAST_PROTOCOL/STATE messages occur from TIPC v2.5.
+ */
+int tipc_link_bc_nack_rcv(struct tipc_link *l, struct sk_buff *skb,
+			  struct sk_buff_head *xmitq)
+{
+	struct tipc_msg *hdr = buf_msg(skb);
+	u32 dnode = msg_destnode(hdr);
+	int mtyp = msg_type(hdr);
+	u16 acked = msg_bcast_ack(hdr);
+	u16 from = acked + 1;
+	u16 to = msg_bcgap_to(hdr);
+	u16 peers_snd_nxt = to + 1;
+	int rc = 0;
+
+	kfree_skb(skb);
+
+	if (!tipc_link_is_up(l) || !l->bc_peer_is_up)
+		return 0;
+
+	if (mtyp != STATE_MSG)
+		return 0;
+
+	if (dnode == tipc_own_addr(l->net)) {
+		tipc_link_bc_ack_rcv(l, acked, xmitq);
+		rc = tipc_link_retrans(l->bc_sndlink, l, from, to, xmitq);
+		l->stats.recv_nacks++;
+		return rc;
+	}
+
+	/* Msg for other node => suppress own NACK at next sync if applicable */
+	if (more(peers_snd_nxt, l->rcv_nxt) && !less(l->rcv_nxt, from))
+		l->nack_state = BC_NACK_SND_SUPPRESS;
+
+	return 0;
+}
+
+void tipc_link_set_queue_limits(struct tipc_link *l, u32 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->backlog[TIPC_SYSTEM_IMPORTANCE].limit   = max_bulk;
+}
+
+/**
+ * link_reset_stats - reset link statistics
+ * @l: pointer to link
+ */
+void tipc_link_reset_stats(struct tipc_link *l)
+{
+	memset(&l->stats, 0, sizeof(l->stats));
+}
+
+static void link_print(struct tipc_link *l, const char *str)
+{
+	struct sk_buff *hskb = skb_peek(&l->transmq);
+	u16 head = hskb ? msg_seqno(buf_msg(hskb)) : l->snd_nxt - 1;
+	u16 tail = l->snd_nxt - 1;
+
+	pr_info("%s Link <%s> state %x\n", str, l->name, l->state);
+	pr_info("XMTQ: %u [%u-%u], BKLGQ: %u, SNDNX: %u, RCVNX: %u\n",
+		skb_queue_len(&l->transmq), head, tail,
+		skb_queue_len(&l->backlogq), l->snd_nxt, l->rcv_nxt);
+}
+
+/* Parse and validate nested (link) properties valid for media, bearer and link
+ */
+int tipc_nl_parse_link_prop(struct nlattr *prop, struct nlattr *props[])
+{
+	int err;
+
+	err = nla_parse_nested(props, TIPC_NLA_PROP_MAX, prop,
+			       tipc_nl_prop_policy, NULL);
+	if (err)
+		return err;
+
+	if (props[TIPC_NLA_PROP_PRIO]) {
+		u32 prio;
+
+		prio = nla_get_u32(props[TIPC_NLA_PROP_PRIO]);
+		if (prio > TIPC_MAX_LINK_PRI)
+			return -EINVAL;
+	}
+
+	if (props[TIPC_NLA_PROP_TOL]) {
+		u32 tol;
+
+		tol = nla_get_u32(props[TIPC_NLA_PROP_TOL]);
+		if ((tol < TIPC_MIN_LINK_TOL) || (tol > TIPC_MAX_LINK_TOL))
+			return -EINVAL;
+	}
+
+	if (props[TIPC_NLA_PROP_WIN]) {
+		u32 win;
+
+		win = nla_get_u32(props[TIPC_NLA_PROP_WIN]);
+		if ((win < TIPC_MIN_LINK_WIN) || (win > TIPC_MAX_LINK_WIN))
+			return -EINVAL;
+	}
+
+	return 0;
+}
+
+static int __tipc_nl_add_stats(struct sk_buff *skb, struct tipc_stats *s)
+{
+	int i;
+	struct nlattr *stats;
+
+	struct nla_map {
+		u32 key;
+		u32 val;
+	};
+
+	struct nla_map map[] = {
+		{TIPC_NLA_STATS_RX_INFO, 0},
+		{TIPC_NLA_STATS_RX_FRAGMENTS, s->recv_fragments},
+		{TIPC_NLA_STATS_RX_FRAGMENTED, s->recv_fragmented},
+		{TIPC_NLA_STATS_RX_BUNDLES, s->recv_bundles},
+		{TIPC_NLA_STATS_RX_BUNDLED, s->recv_bundled},
+		{TIPC_NLA_STATS_TX_INFO, 0},
+		{TIPC_NLA_STATS_TX_FRAGMENTS, s->sent_fragments},
+		{TIPC_NLA_STATS_TX_FRAGMENTED, s->sent_fragmented},
+		{TIPC_NLA_STATS_TX_BUNDLES, s->sent_bundles},
+		{TIPC_NLA_STATS_TX_BUNDLED, s->sent_bundled},
+		{TIPC_NLA_STATS_MSG_PROF_TOT, (s->msg_length_counts) ?
+			s->msg_length_counts : 1},
+		{TIPC_NLA_STATS_MSG_LEN_CNT, s->msg_length_counts},
+		{TIPC_NLA_STATS_MSG_LEN_TOT, s->msg_lengths_total},
+		{TIPC_NLA_STATS_MSG_LEN_P0, s->msg_length_profile[0]},
+		{TIPC_NLA_STATS_MSG_LEN_P1, s->msg_length_profile[1]},
+		{TIPC_NLA_STATS_MSG_LEN_P2, s->msg_length_profile[2]},
+		{TIPC_NLA_STATS_MSG_LEN_P3, s->msg_length_profile[3]},
+		{TIPC_NLA_STATS_MSG_LEN_P4, s->msg_length_profile[4]},
+		{TIPC_NLA_STATS_MSG_LEN_P5, s->msg_length_profile[5]},
+		{TIPC_NLA_STATS_MSG_LEN_P6, s->msg_length_profile[6]},
+		{TIPC_NLA_STATS_RX_STATES, s->recv_states},
+		{TIPC_NLA_STATS_RX_PROBES, s->recv_probes},
+		{TIPC_NLA_STATS_RX_NACKS, s->recv_nacks},
+		{TIPC_NLA_STATS_RX_DEFERRED, s->deferred_recv},
+		{TIPC_NLA_STATS_TX_STATES, s->sent_states},
+		{TIPC_NLA_STATS_TX_PROBES, s->sent_probes},
+		{TIPC_NLA_STATS_TX_NACKS, s->sent_nacks},
+		{TIPC_NLA_STATS_TX_ACKS, s->sent_acks},
+		{TIPC_NLA_STATS_RETRANSMITTED, s->retransmitted},
+		{TIPC_NLA_STATS_DUPLICATES, s->duplicates},
+		{TIPC_NLA_STATS_LINK_CONGS, s->link_congs},
+		{TIPC_NLA_STATS_MAX_QUEUE, s->max_queue_sz},
+		{TIPC_NLA_STATS_AVG_QUEUE, s->queue_sz_counts ?
+			(s->accu_queue_sz / s->queue_sz_counts) : 0}
+	};
+
+	stats = nla_nest_start(skb, TIPC_NLA_LINK_STATS);
+	if (!stats)
+		return -EMSGSIZE;
+
+	for (i = 0; i <  ARRAY_SIZE(map); i++)
+		if (nla_put_u32(skb, map[i].key, map[i].val))
+			goto msg_full;
+
+	nla_nest_end(skb, stats);
+
+	return 0;
+msg_full:
+	nla_nest_cancel(skb, stats);
+
+	return -EMSGSIZE;
+}
+
+/* Caller should hold appropriate locks to protect the link */
+int __tipc_nl_add_link(struct net *net, struct tipc_nl_msg *msg,
+		       struct tipc_link *link, int nlflags)
+{
+	u32 self = tipc_own_addr(net);
+	struct nlattr *attrs;
+	struct nlattr *prop;
+	void *hdr;
+	int err;
+
+	hdr = genlmsg_put(msg->skb, msg->portid, msg->seq, &tipc_genl_family,
+			  nlflags, TIPC_NL_LINK_GET);
+	if (!hdr)
+		return -EMSGSIZE;
+
+	attrs = nla_nest_start(msg->skb, TIPC_NLA_LINK);
+	if (!attrs)
+		goto msg_full;
+
+	if (nla_put_string(msg->skb, TIPC_NLA_LINK_NAME, link->name))
+		goto attr_msg_full;
+	if (nla_put_u32(msg->skb, TIPC_NLA_LINK_DEST, tipc_cluster_mask(self)))
+		goto attr_msg_full;
+	if (nla_put_u32(msg->skb, TIPC_NLA_LINK_MTU, link->mtu))
+		goto attr_msg_full;
+	if (nla_put_u32(msg->skb, TIPC_NLA_LINK_RX, link->stats.recv_pkts))
+		goto attr_msg_full;
+	if (nla_put_u32(msg->skb, TIPC_NLA_LINK_TX, link->stats.sent_pkts))
+		goto attr_msg_full;
+
+	if (tipc_link_is_up(link))
+		if (nla_put_flag(msg->skb, TIPC_NLA_LINK_UP))
+			goto attr_msg_full;
+	if (link->active)
+		if (nla_put_flag(msg->skb, TIPC_NLA_LINK_ACTIVE))
+			goto attr_msg_full;
+
+	prop = nla_nest_start(msg->skb, TIPC_NLA_LINK_PROP);
+	if (!prop)
+		goto attr_msg_full;
+	if (nla_put_u32(msg->skb, TIPC_NLA_PROP_PRIO, link->priority))
+		goto prop_msg_full;
+	if (nla_put_u32(msg->skb, TIPC_NLA_PROP_TOL, link->tolerance))
+		goto prop_msg_full;
+	if (nla_put_u32(msg->skb, TIPC_NLA_PROP_WIN,
+			link->window))
+		goto prop_msg_full;
+	if (nla_put_u32(msg->skb, TIPC_NLA_PROP_PRIO, link->priority))
+		goto prop_msg_full;
+	nla_nest_end(msg->skb, prop);
+
+	err = __tipc_nl_add_stats(msg->skb, &link->stats);
+	if (err)
+		goto attr_msg_full;
+
+	nla_nest_end(msg->skb, attrs);
+	genlmsg_end(msg->skb, hdr);
+
+	return 0;
+
+prop_msg_full:
+	nla_nest_cancel(msg->skb, prop);
+attr_msg_full:
+	nla_nest_cancel(msg->skb, attrs);
+msg_full:
+	genlmsg_cancel(msg->skb, hdr);
+
+	return -EMSGSIZE;
+}
+
+static int __tipc_nl_add_bc_link_stat(struct sk_buff *skb,
+				      struct tipc_stats *stats)
+{
+	int i;
+	struct nlattr *nest;
+
+	struct nla_map {
+		__u32 key;
+		__u32 val;
+	};
+
+	struct nla_map map[] = {
+		{TIPC_NLA_STATS_RX_INFO, stats->recv_pkts},
+		{TIPC_NLA_STATS_RX_FRAGMENTS, stats->recv_fragments},
+		{TIPC_NLA_STATS_RX_FRAGMENTED, stats->recv_fragmented},
+		{TIPC_NLA_STATS_RX_BUNDLES, stats->recv_bundles},
+		{TIPC_NLA_STATS_RX_BUNDLED, stats->recv_bundled},
+		{TIPC_NLA_STATS_TX_INFO, stats->sent_pkts},
+		{TIPC_NLA_STATS_TX_FRAGMENTS, stats->sent_fragments},
+		{TIPC_NLA_STATS_TX_FRAGMENTED, stats->sent_fragmented},
+		{TIPC_NLA_STATS_TX_BUNDLES, stats->sent_bundles},
+		{TIPC_NLA_STATS_TX_BUNDLED, stats->sent_bundled},
+		{TIPC_NLA_STATS_RX_NACKS, stats->recv_nacks},
+		{TIPC_NLA_STATS_RX_DEFERRED, stats->deferred_recv},
+		{TIPC_NLA_STATS_TX_NACKS, stats->sent_nacks},
+		{TIPC_NLA_STATS_TX_ACKS, stats->sent_acks},
+		{TIPC_NLA_STATS_RETRANSMITTED, stats->retransmitted},
+		{TIPC_NLA_STATS_DUPLICATES, stats->duplicates},
+		{TIPC_NLA_STATS_LINK_CONGS, stats->link_congs},
+		{TIPC_NLA_STATS_MAX_QUEUE, stats->max_queue_sz},
+		{TIPC_NLA_STATS_AVG_QUEUE, stats->queue_sz_counts ?
+			(stats->accu_queue_sz / stats->queue_sz_counts) : 0}
+	};
+
+	nest = nla_nest_start(skb, TIPC_NLA_LINK_STATS);
+	if (!nest)
+		return -EMSGSIZE;
+
+	for (i = 0; i <  ARRAY_SIZE(map); i++)
+		if (nla_put_u32(skb, map[i].key, map[i].val))
+			goto msg_full;
+
+	nla_nest_end(skb, nest);
+
+	return 0;
+msg_full:
+	nla_nest_cancel(skb, nest);
+
+	return -EMSGSIZE;
+}
+
+int tipc_nl_add_bc_link(struct net *net, struct tipc_nl_msg *msg)
+{
+	int err;
+	void *hdr;
+	struct nlattr *attrs;
+	struct nlattr *prop;
+	struct tipc_net *tn = net_generic(net, tipc_net_id);
+	struct tipc_link *bcl = tn->bcl;
+
+	if (!bcl)
+		return 0;
+
+	tipc_bcast_lock(net);
+
+	hdr = genlmsg_put(msg->skb, msg->portid, msg->seq, &tipc_genl_family,
+			  NLM_F_MULTI, TIPC_NL_LINK_GET);
+	if (!hdr) {
+		tipc_bcast_unlock(net);
+		return -EMSGSIZE;
+	}
+
+	attrs = nla_nest_start(msg->skb, TIPC_NLA_LINK);
+	if (!attrs)
+		goto msg_full;
+
+	/* The broadcast link is always up */
+	if (nla_put_flag(msg->skb, TIPC_NLA_LINK_UP))
+		goto attr_msg_full;
+
+	if (nla_put_flag(msg->skb, TIPC_NLA_LINK_BROADCAST))
+		goto attr_msg_full;
+	if (nla_put_string(msg->skb, TIPC_NLA_LINK_NAME, bcl->name))
+		goto attr_msg_full;
+	if (nla_put_u32(msg->skb, TIPC_NLA_LINK_RX, 0))
+		goto attr_msg_full;
+	if (nla_put_u32(msg->skb, TIPC_NLA_LINK_TX, 0))
+		goto attr_msg_full;
+
+	prop = nla_nest_start(msg->skb, TIPC_NLA_LINK_PROP);
+	if (!prop)
+		goto attr_msg_full;
+	if (nla_put_u32(msg->skb, TIPC_NLA_PROP_WIN, bcl->window))
+		goto prop_msg_full;
+	nla_nest_end(msg->skb, prop);
+
+	err = __tipc_nl_add_bc_link_stat(msg->skb, &bcl->stats);
+	if (err)
+		goto attr_msg_full;
+
+	tipc_bcast_unlock(net);
+	nla_nest_end(msg->skb, attrs);
+	genlmsg_end(msg->skb, hdr);
+
+	return 0;
+
+prop_msg_full:
+	nla_nest_cancel(msg->skb, prop);
+attr_msg_full:
+	nla_nest_cancel(msg->skb, attrs);
+msg_full:
+	tipc_bcast_unlock(net);
+	genlmsg_cancel(msg->skb, hdr);
+
+	return -EMSGSIZE;
+}
+
+void tipc_link_set_tolerance(struct tipc_link *l, u32 tol,
+			     struct sk_buff_head *xmitq)
+{
+	l->tolerance = tol;
+	if (l->bc_rcvlink)
+		l->bc_rcvlink->tolerance = tol;
+	if (link_is_up(l))
+		tipc_link_build_proto_msg(l, STATE_MSG, 0, 0, 0, tol, 0, xmitq);
+}
+
+void tipc_link_set_prio(struct tipc_link *l, u32 prio,
+			struct sk_buff_head *xmitq)
+{
+	l->priority = prio;
+	tipc_link_build_proto_msg(l, STATE_MSG, 0, 0, 0, 0, prio, xmitq);
+}
+
+void tipc_link_set_abort_limit(struct tipc_link *l, u32 limit)
+{
+	l->abort_limit = limit;
+}