Adding upstream version 6.6.15.upstream/6.6.15

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

1 files changed, 3009 insertions, 0 deletions

diff --git a/net/tipc/link.c b/net/tipc/link.c
new file mode 100644
index 0000000000..d014382365
--- /dev/null
+++ b/net/tipc/link.c
@@ -0,0 +1,3009 @@
+/*
+ * 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 "trace.h"
+#include "crypto.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
+ * @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
+ * @session: session to be used by link
+ * @snd_nxt_state: next send seq number
+ * @rcv_nxt_state: next rcv seq number
+ * @in_session: have received ACTIVATE_MSG from peer
+ * @active: link is active
+ * @if_name: associated interface name
+ * @rst_cnt: link reset counter
+ * @drop_point: seq number for failover handling (FIXME)
+ * @failover_reasm_skb: saved failover msg ptr (FIXME)
+ * @failover_deferdq: deferred message queue for failover processing (FIXME)
+ * @transmq: the link's transmit queue
+ * @backlog: link's backlog by priority (importance)
+ * @snd_nxt: next sequence number to be used
+ * @rcv_unacked: # messages read by user, but not yet acked back to peer
+ * @deferdq: deferred receive queue
+ * @window: sliding window size for congestion handling
+ * @min_win: minimal send window to be used by link
+ * @ssthresh: slow start threshold for congestion handling
+ * @max_win: maximal send window to be used by link
+ * @cong_acks: congestion acks for congestion avoidance (FIXME)
+ * @checkpoint: seq number for congestion window size handling
+ * @reasm_tnlmsg: fragmentation/reassembly area for tunnel protocol message
+ * @last_gap: last gap ack blocks for bcast (FIXME)
+ * @last_ga: ptr to gap ack blocks
+ * @bc_rcvlink: the peer specific link used for broadcast reception
+ * @bc_sndlink: the namespace global link used for broadcast sending
+ * @nack_state: bcast nack state
+ * @bc_peer_is_up: peer has acked the bcast init msg
+ */
+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;
+	struct sk_buff_head failover_deferdq;
+
+	/* 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;
+
+	/* 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;
+	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;
+	u16 acked;
+	u16 last_gap;
+	struct tipc_gap_ack_blks *last_ga;
+	struct tipc_link *bc_rcvlink;
+	struct tipc_link *bc_sndlink;
+	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_LIM  (jiffies + msecs_to_jiffies(10))
+#define TIPC_UC_RETR_TIME (jiffies + msecs_to_jiffies(1))
+
+/* 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 u8 __tipc_build_gap_ack_blks(struct tipc_gap_ack_blks *ga,
+				    struct tipc_link *l, u8 start_index);
+static u16 tipc_build_gap_ack_blks(struct tipc_link *l, struct tipc_msg *hdr);
+static int tipc_link_advance_transmq(struct tipc_link *l, struct tipc_link *r,
+				     u16 acked, u16 gap,
+				     struct tipc_gap_ack_blks *ga,
+				     struct sk_buff_head *xmitq,
+				     bool *retransmitted, int *rc);
+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)
+ */
+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_min_win(struct tipc_link *l)
+{
+	return l->min_win;
+}
+
+int tipc_link_max_win(struct tipc_link *l)
+{
+	return l->max_win;
+}
+
+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;
+}
+
+struct net *tipc_link_net(struct tipc_link *l)
+{
+	return l->net;
+}
+
+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, 0, NULL, xmitq, NULL);
+	trace_tipc_link_reset(rcv_l, TIPC_DUMP_ALL, "bclink removed!");
+	tipc_link_reset(rcv_l);
+	rcv_l->state = LINK_RESET;
+	if (!snd_l->ackers) {
+		trace_tipc_link_reset(snd_l, TIPC_DUMP_ALL, "zero 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;
+}
+
+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;
+}
+
+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
+ * @net: pointer to associated network namespace
+ * @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
+ * @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
+ * @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
+ * @self: local unicast link id
+ * @peer_id: 128-bit ID of peer
+ *
+ * Return: 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,
+		      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,
+		      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, min_win, max_win);
+	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->failover_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
+ * @net: pointer to associated network namespace
+ * @mtu: mtu to be used initially if no peers
+ * @min_win: minimal send window to be used by link
+ * @max_win: maximal send window to be used by link
+ * @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
+ * @ownnode: identity of own node
+ * @peer: node id of peer node
+ * @peer_id: 128-bit ID of peer
+ * @peer_caps: bitmap describing peer node capabilities
+ * @bc_sndlink: the namespace global link used for broadcast sending
+ *
+ * Return: true if link was created, otherwise false
+ */
+bool tipc_link_bc_create(struct net *net, u32 ownnode, u32 peer, u8 *peer_id,
+			 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,
+			 struct tipc_link **link)
+{
+	struct tipc_link *l;
+
+	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;
+	if (peer_id) {
+		char peer_str[NODE_ID_STR_LEN] = {0,};
+
+		tipc_nodeid2string(peer_str, peer_id);
+		if (strlen(peer_str) > 16)
+			sprintf(peer_str, "%x", peer);
+		/* Broadcast receiver link name: "broadcast-link:<peer>" */
+		snprintf(l->name, sizeof(l->name), "%s:%s", tipc_bclink_name,
+			 peer_str);
+	} else {
+		strcpy(l->name, tipc_bclink_name);
+	}
+	trace_tipc_link_reset(l, TIPC_DUMP_ALL, "bclink created!");
+	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_toggle_rcast(net, false);
+
+	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;
+	int old_state = l->state;
+
+	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;
+			break;
+		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);
+	}
+	trace_tipc_link_fsm(l->name, old_state, l->state, evt);
+	return rc;
+illegal_evt:
+	pr_err("Illegal FSM event %x in state %x on link %s\n",
+	       evt, l->state, l->name);
+	trace_tipc_link_fsm(l->name, old_state, l->state, evt);
+	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_inner_hdr(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_too_silent - check if link is "too silent"
+ * @l: tipc link to be checked
+ *
+ * Return: true if the link 'silent_intv_cnt' is about to reach the
+ * 'abort_limit' value, otherwise false
+ */
+bool tipc_link_too_silent(struct tipc_link *l)
+{
+	return (l->silent_intv_cnt + 2 > l->abort_limit);
+}
+
+/* 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;
+
+	trace_tipc_link_timeout(l, TIPC_DUMP_NONE, " ");
+	trace_tipc_link_too_silent(l, TIPC_DUMP_ALL, " ");
+	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);
+		probe = mstate->probing;
+		probe |= l->silent_intv_cnt;
+		if (probe || mstate->monitoring)
+			l->silent_intv_cnt++;
+		probe |= !skb_queue_empty(&l->deferdq);
+		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;
+		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++;
+	trace_tipc_link_conges(l, TIPC_DUMP_ALL, "wakeup scheduled!");
+	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);
+
+}
+
+/**
+ * tipc_link_set_skb_retransmit_time - set the time at which retransmission of
+ *                                     the given skb should be next attempted
+ * @skb: skb to set a future retransmission time for
+ * @l: link the skb will be transmitted on
+ */
+static void tipc_link_set_skb_retransmit_time(struct sk_buff *skb,
+					      struct tipc_link *l)
+{
+	if (link_is_bc_sndlink(l))
+		TIPC_SKB_CB(skb)->nxt_retr = TIPC_BC_RETR_LIM;
+	else
+		TIPC_SKB_CB(skb)->nxt_retr = TIPC_UC_RETR_TIME;
+}
+
+void tipc_link_reset(struct tipc_link *l)
+{
+	struct sk_buff_head list;
+	u32 imp;
+
+	__skb_queue_head_init(&list);
+
+	l->in_session = false;
+	/* Force re-synch of peer session number before establishing */
+	l->peer_session--;
+	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);
+	__skb_queue_purge(&l->failover_deferdq);
+	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;
+	l->rcv_nxt = 1;
+	l->snd_nxt_state = 1;
+	l->rcv_nxt_state = 1;
+	l->acked = 0;
+	l->last_gap = 0;
+	kfree(l->last_ga);
+	l->last_ga = NULL;
+	l->silent_intv_cnt = 0;
+	l->rst_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
+ * @l: link to use
+ * @list: chain of buffers containing message
+ * @xmitq: returned list of packets to be sent by caller
+ *
+ * Consumes the buffer chain.
+ * Messages at TIPC_SYSTEM_IMPORTANCE are always accepted
+ * Return: 0 if success, or errno: -ELINKCONG, -EMSGSIZE or -ENOBUFS
+ */
+int tipc_link_xmit(struct tipc_link *l, struct sk_buff_head *list,
+		   struct sk_buff_head *xmitq)
+{
+	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;
+	int pkt_cnt = skb_queue_len(list);
+	unsigned int mss = tipc_link_mss(l);
+	unsigned int cwin = l->window;
+	unsigned int mtu = l->mtu;
+	struct tipc_msg *hdr;
+	bool new_bundle;
+	int rc = 0;
+	int imp;
+
+	if (pkt_cnt <= 0)
+		return 0;
+
+	hdr = buf_msg(skb_peek(list));
+	if (unlikely(msg_size(hdr) > mtu)) {
+		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;
+	}
+
+	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 = __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) {
+				kfree_skb(skb);
+				__skb_queue_purge(list);
+				return -ENOBUFS;
+			}
+			__skb_queue_tail(transmq, skb);
+			tipc_link_set_skb_retransmit_time(skb, l);
+			__skb_queue_tail(xmitq, _skb);
+			TIPC_SKB_CB(skb)->ackers = l->ackers;
+			l->rcv_unacked = 0;
+			l->stats.sent_pkts++;
+			seqno++;
+			continue;
+		}
+		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].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 = min_t(u16, l->ssthresh, l->window);
+		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;
+	u16 ack = l->rcv_nxt - 1;
+	u16 seqno = l->snd_nxt;
+	struct tipc_msg *hdr;
+	u16 cwin = l->window;
+	u32 imp;
+
+	while (skb_queue_len(txq) < cwin) {
+		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);
+		tipc_link_set_skb_retransmit_time(skb, l);
+
+		__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;
+}
+
+/**
+ * link_retransmit_failure() - Detect repeated retransmit failures
+ * @l: tipc link sender
+ * @r: tipc link receiver (= l in case of unicast)
+ * @rc: returned code
+ *
+ * Return: true if the repeated retransmit failures happens, otherwise
+ * false
+ */
+static bool link_retransmit_failure(struct tipc_link *l, struct tipc_link *r,
+				    int *rc)
+{
+	struct sk_buff *skb = skb_peek(&l->transmq);
+	struct tipc_msg *hdr;
+
+	if (!skb)
+		return false;
+
+	if (!TIPC_SKB_CB(skb)->retr_cnt)
+		return false;
+
+	if (!time_after(jiffies, TIPC_SKB_CB(skb)->retr_stamp +
+			msecs_to_jiffies(r->tolerance * 10)))
+		return false;
+
+	hdr = buf_msg(skb);
+	if (link_is_bc_sndlink(l) && !less(r->acked, msg_seqno(hdr)))
+		return false;
+
+	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, dest: %x\n",
+		msg_seqno(hdr), msg_prevnode(hdr), msg_destnode(hdr));
+	pr_info("retr_stamp %d, retr_cnt %d\n",
+		jiffies_to_msecs(TIPC_SKB_CB(skb)->retr_stamp),
+		TIPC_SKB_CB(skb)->retr_cnt);
+
+	trace_tipc_list_dump(&l->transmq, true, "retrans failure!");
+	trace_tipc_link_dump(l, TIPC_DUMP_NONE, "retrans failure!");
+	trace_tipc_link_dump(r, TIPC_DUMP_NONE, "retrans failure!");
+
+	if (link_is_bc_sndlink(l)) {
+		r->state = LINK_RESET;
+		*rc |= TIPC_LINK_DOWN_EVT;
+	} else {
+		*rc |= tipc_link_fsm_evt(l, LINK_FAILURE_EVT);
+	}
+
+	return true;
+}
+
+/* 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;
+		}
+		fallthrough;
+	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;
+#ifdef CONFIG_TIPC_CRYPTO
+	case MSG_CRYPTO:
+		if (sysctl_tipc_key_exchange_enabled &&
+		    TIPC_SKB_CB(skb)->decrypted) {
+			tipc_crypto_msg_rcv(l->net, skb);
+			return true;
+		}
+		fallthrough;
+#endif
+	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 sk_buff **reasm_skb)
+{
+	struct tipc_msg *hdr = buf_msg(skb);
+	struct sk_buff *iskb;
+	struct sk_buff_head tmpq;
+	int usr = msg_user(hdr);
+	int pos = 0;
+
+	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);
+	}
+
+	kfree_skb(skb);
+	return 0;
+}
+
+/* tipc_link_tnl_rcv() - receive TUNNEL_PROTOCOL message, drop or process the
+ *			 inner message along with the ones in the old link's
+ *			 deferdq
+ * @l: tunnel link
+ * @skb: TUNNEL_PROTOCOL message
+ * @inputq: queue to put messages ready for delivery
+ */
+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;
+	int ipos = 0;
+	int rc = 0;
+	u16 seqno;
+
+	if (msg_type(hdr) == SYNCH_MSG) {
+		kfree_skb(skb);
+		return 0;
+	}
+
+	/* 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)));
+
+	return rc;
+}
+
+/**
+ * tipc_get_gap_ack_blks - get Gap ACK blocks from PROTOCOL/STATE_MSG
+ * @ga: returned pointer to the Gap ACK blocks if any
+ * @l: the tipc link
+ * @hdr: the PROTOCOL/STATE_MSG header
+ * @uc: desired Gap ACK blocks type, i.e. unicast (= 1) or broadcast (= 0)
+ *
+ * Return: the total Gap ACK blocks size
+ */
+u16 tipc_get_gap_ack_blks(struct tipc_gap_ack_blks **ga, struct tipc_link *l,
+			  struct tipc_msg *hdr, bool uc)
+{
+	struct tipc_gap_ack_blks *p;
+	u16 sz = 0;
+
+	/* Does peer support the Gap ACK blocks feature? */
+	if (l->peer_caps & TIPC_GAP_ACK_BLOCK) {
+		p = (struct tipc_gap_ack_blks *)msg_data(hdr);
+		sz = ntohs(p->len);
+		/* Sanity check */
+		if (sz == struct_size(p, gacks, size_add(p->ugack_cnt, p->bgack_cnt))) {
+			/* Good, check if the desired type exists */
+			if ((uc && p->ugack_cnt) || (!uc && p->bgack_cnt))
+				goto ok;
+		/* Backward compatible: peer might not support bc, but uc? */
+		} else if (uc && sz == struct_size(p, gacks, p->ugack_cnt)) {
+			if (p->ugack_cnt) {
+				p->bgack_cnt = 0;
+				goto ok;
+			}
+		}
+	}
+	/* Other cases: ignore! */
+	p = NULL;
+
+ok:
+	*ga = p;
+	return sz;
+}
+
+static u8 __tipc_build_gap_ack_blks(struct tipc_gap_ack_blks *ga,
+				    struct tipc_link *l, u8 start_index)
+{
+	struct tipc_gap_ack *gacks = &ga->gacks[start_index];
+	struct sk_buff *skb = skb_peek(&l->deferdq);
+	u16 expect, seqno = 0;
+	u8 n = 0;
+
+	if (!skb)
+		return 0;
+
+	expect = buf_seqno(skb);
+	skb_queue_walk(&l->deferdq, skb) {
+		seqno = buf_seqno(skb);
+		if (unlikely(more(seqno, expect))) {
+			gacks[n].ack = htons(expect - 1);
+			gacks[n].gap = htons(seqno - expect);
+			if (++n >= MAX_GAP_ACK_BLKS / 2) {
+				pr_info_ratelimited("Gacks on %s: %d, ql: %d!\n",
+						    l->name, n,
+						    skb_queue_len(&l->deferdq));
+				return n;
+			}
+		} else if (unlikely(less(seqno, expect))) {
+			pr_warn("Unexpected skb in deferdq!\n");
+			continue;
+		}
+		expect = seqno + 1;
+	}
+
+	/* last block */
+	gacks[n].ack = htons(seqno);
+	gacks[n].gap = 0;
+	n++;
+	return n;
+}
+
+/* tipc_build_gap_ack_blks - build Gap ACK blocks
+ * @l: tipc unicast link
+ * @hdr: the tipc message buffer to store the Gap ACK blocks after built
+ *
+ * The function builds Gap ACK blocks for both the unicast & broadcast receiver
+ * links of a certain peer, the buffer after built has the network data format
+ * as found at the struct tipc_gap_ack_blks definition.
+ *
+ * returns the actual allocated memory size
+ */
+static u16 tipc_build_gap_ack_blks(struct tipc_link *l, struct tipc_msg *hdr)
+{
+	struct tipc_link *bcl = l->bc_rcvlink;
+	struct tipc_gap_ack_blks *ga;
+	u16 len;
+
+	ga = (struct tipc_gap_ack_blks *)msg_data(hdr);
+
+	/* Start with broadcast link first */
+	tipc_bcast_lock(bcl->net);
+	msg_set_bcast_ack(hdr, bcl->rcv_nxt - 1);
+	msg_set_bc_gap(hdr, link_bc_rcv_gap(bcl));
+	ga->bgack_cnt = __tipc_build_gap_ack_blks(ga, bcl, 0);
+	tipc_bcast_unlock(bcl->net);
+
+	/* Now for unicast link, but an explicit NACK only (???) */
+	ga->ugack_cnt = (msg_seq_gap(hdr)) ?
+			__tipc_build_gap_ack_blks(ga, l, ga->bgack_cnt) : 0;
+
+	/* Total len */
+	len = struct_size(ga, gacks, size_add(ga->bgack_cnt, ga->ugack_cnt));
+	ga->len = htons(len);
+	return len;
+}
+
+/* tipc_link_advance_transmq - advance TIPC link transmq queue by releasing
+ *			       acked packets, also doing retransmissions if
+ *			       gaps found
+ * @l: tipc link with transmq queue to be advanced
+ * @r: tipc link "receiver" i.e. in case of broadcast (= "l" if unicast)
+ * @acked: seqno of last packet acked by peer without any gaps before
+ * @gap: # of gap packets
+ * @ga: buffer pointer to Gap ACK blocks from peer
+ * @xmitq: queue for accumulating the retransmitted packets if any
+ * @retransmitted: returned boolean value if a retransmission is really issued
+ * @rc: returned code e.g. TIPC_LINK_DOWN_EVT if a repeated retransmit failures
+ *      happens (- unlikely case)
+ *
+ * Return: the number of packets released from the link transmq
+ */
+static int tipc_link_advance_transmq(struct tipc_link *l, struct tipc_link *r,
+				     u16 acked, u16 gap,
+				     struct tipc_gap_ack_blks *ga,
+				     struct sk_buff_head *xmitq,
+				     bool *retransmitted, int *rc)
+{
+	struct tipc_gap_ack_blks *last_ga = r->last_ga, *this_ga = NULL;
+	struct tipc_gap_ack *gacks = NULL;
+	struct sk_buff *skb, *_skb, *tmp;
+	struct tipc_msg *hdr;
+	u32 qlen = skb_queue_len(&l->transmq);
+	u16 nacked = acked, ngap = gap, gack_cnt = 0;
+	u16 bc_ack = l->bc_rcvlink->rcv_nxt - 1;
+	u16 ack = l->rcv_nxt - 1;
+	u16 seqno, n = 0;
+	u16 end = r->acked, start = end, offset = r->last_gap;
+	u16 si = (last_ga) ? last_ga->start_index : 0;
+	bool is_uc = !link_is_bc_sndlink(l);
+	bool bc_has_acked = false;
+
+	trace_tipc_link_retrans(r, acked + 1, acked + gap, &l->transmq);
+
+	/* Determine Gap ACK blocks if any for the particular link */
+	if (ga && is_uc) {
+		/* Get the Gap ACKs, uc part */
+		gack_cnt = ga->ugack_cnt;
+		gacks = &ga->gacks[ga->bgack_cnt];
+	} else if (ga) {
+		/* Copy the Gap ACKs, bc part, for later renewal if needed */
+		this_ga = kmemdup(ga, struct_size(ga, gacks, ga->bgack_cnt),
+				  GFP_ATOMIC);
+		if (likely(this_ga)) {
+			this_ga->start_index = 0;
+			/* Start with the bc Gap ACKs */
+			gack_cnt = this_ga->bgack_cnt;
+			gacks = &this_ga->gacks[0];
+		} else {
+			/* Hmm, we can get in trouble..., simply ignore it */
+			pr_warn_ratelimited("Ignoring bc Gap ACKs, no memory\n");
+		}
+	}
+
+	/* Advance the link transmq */
+	skb_queue_walk_safe(&l->transmq, skb, tmp) {
+		seqno = buf_seqno(skb);
+
+next_gap_ack:
+		if (less_eq(seqno, nacked)) {
+			if (is_uc)
+				goto release;
+			/* Skip packets peer has already acked */
+			if (!more(seqno, r->acked))
+				continue;
+			/* Get the next of last Gap ACK blocks */
+			while (more(seqno, end)) {
+				if (!last_ga || si >= last_ga->bgack_cnt)
+					break;
+				start = end + offset + 1;
+				end = ntohs(last_ga->gacks[si].ack);
+				offset = ntohs(last_ga->gacks[si].gap);
+				si++;
+				WARN_ONCE(more(start, end) ||
+					  (!offset &&
+					   si < last_ga->bgack_cnt) ||
+					  si > MAX_GAP_ACK_BLKS,
+					  "Corrupted Gap ACK: %d %d %d %d %d\n",
+					  start, end, offset, si,
+					  last_ga->bgack_cnt);
+			}
+			/* Check against the last Gap ACK block */
+			if (tipc_in_range(seqno, start, end))
+				continue;
+			/* Update/release the packet peer is acking */
+			bc_has_acked = true;
+			if (--TIPC_SKB_CB(skb)->ackers)
+				continue;
+release:
+			/* release skb */
+			__skb_unlink(skb, &l->transmq);
+			kfree_skb(skb);
+		} else if (less_eq(seqno, nacked + ngap)) {
+			/* First gap: check if repeated retrans failures? */
+			if (unlikely(seqno == acked + 1 &&
+				     link_retransmit_failure(l, r, rc))) {
+				/* Ignore this bc Gap ACKs if any */
+				kfree(this_ga);
+				this_ga = NULL;
+				break;
+			}
+			/* retransmit skb if unrestricted*/
+			if (time_before(jiffies, TIPC_SKB_CB(skb)->nxt_retr))
+				continue;
+			tipc_link_set_skb_retransmit_time(skb, l);
+			_skb = pskb_copy(skb, GFP_ATOMIC);
+			if (!_skb)
+				continue;
+			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++;
+			if (!is_uc)
+				r->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;
+		} else {
+			/* retry with Gap ACK blocks if any */
+			if (n >= gack_cnt)
+				break;
+			nacked = ntohs(gacks[n].ack);
+			ngap = ntohs(gacks[n].gap);
+			n++;
+			goto next_gap_ack;
+		}
+	}
+
+	/* Renew last Gap ACK blocks for bc if needed */
+	if (bc_has_acked) {
+		if (this_ga) {
+			kfree(last_ga);
+			r->last_ga = this_ga;
+			r->last_gap = gap;
+		} else if (last_ga) {
+			if (less(acked, start)) {
+				si--;
+				offset = start - acked - 1;
+			} else if (less(acked, end)) {
+				acked = end;
+			}
+			if (si < last_ga->bgack_cnt) {
+				last_ga->start_index = si;
+				r->last_gap = offset;
+			} else {
+				kfree(last_ga);
+				r->last_ga = NULL;
+				r->last_gap = 0;
+			}
+		} else {
+			r->last_gap = 0;
+		}
+		r->acked = acked;
+	} else {
+		kfree(this_ga);
+	}
+
+	return qlen - skb_queue_len(&l->transmq);
+}
+
+/* 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;
+	struct sk_buff_head *dfq = &l->deferdq;
+	u32 defq_len = skb_queue_len(dfq);
+	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 (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;
+}
+
+/* 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 = buf_msg(skb);
+	u16 seqno, rcv_nxt, win_lim;
+	int released = 0;
+	int rc = 0;
+
+	/* Verify and update link state */
+	if (unlikely(msg_user(hdr) == LINK_PROTOCOL))
+		return tipc_link_proto_rcv(l, skb, xmitq);
+
+	/* Don't send probe at next timeout expiration */
+	l->silent_intv_cnt = 0;
+
+	do {
+		hdr = buf_msg(skb);
+		seqno = msg_seqno(hdr);
+		rcv_nxt = l->rcv_nxt;
+		win_lim = rcv_nxt + TIPC_MAX_LINK_WIN;
+
+		if (unlikely(!link_is_up(l))) {
+			if (l->state == LINK_ESTABLISHING)
+				rc = TIPC_LINK_UP_EVT;
+			kfree_skb(skb);
+			break;
+		}
+
+		/* Drop if outside receive window */
+		if (unlikely(less(seqno, rcv_nxt) || more(seqno, win_lim))) {
+			l->stats.duplicates++;
+			kfree_skb(skb);
+			break;
+		}
+		released += tipc_link_advance_transmq(l, l, msg_ack(hdr), 0,
+						      NULL, NULL, NULL, NULL);
+
+		/* Defer delivery if sequence gap */
+		if (unlikely(seqno != rcv_nxt)) {
+			if (!__tipc_skb_queue_sorted(defq, seqno, skb))
+				l->stats.duplicates++;
+			rc |= tipc_link_build_nack_msg(l, xmitq);
+			break;
+		}
+
+		/* Deliver packet */
+		l->rcv_nxt++;
+		l->stats.recv_pkts++;
+
+		if (unlikely(msg_user(hdr) == TUNNEL_PROTOCOL))
+			rc |= tipc_link_tnl_rcv(l, skb, l->inputq);
+		else if (!tipc_data_input(l, skb, l->inputq))
+			rc |= tipc_link_input(l, skb, l->inputq, &l->reasm_buf);
+		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 = __tipc_skb_dequeue(defq, l->rcv_nxt)));
+
+	/* 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;
+}
+
+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_mon_state *mstate = &l->mon_state;
+	struct sk_buff_head *dfq = &l->deferdq;
+	struct tipc_link *bcl = l->bc_rcvlink;
+	struct tipc_msg *hdr;
+	struct sk_buff *skb;
+	bool node_up = link_is_up(bcl);
+	u16 glen = 0, bc_rcvgap = 0;
+	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 ((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,
+			      tipc_max_domain_size + MAX_GAP_ACK_BLKS_SZ,
+			      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);
+		bc_rcvgap = link_bc_rcv_gap(bcl);
+		msg_set_bc_gap(hdr, bc_rcvgap);
+		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, hdr);
+		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);
+		l->stats.sent_states++;
+		l->rcv_unacked = 0;
+	} else {
+		/* RESET_MSG or ACTIVATE_MSG */
+		if (mtyp == ACTIVATE_MSG) {
+			msg_set_dest_session_valid(hdr, 1);
+			msg_set_dest_session(hdr, l->peer_session);
+		}
+		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++;
+	if (bc_rcvgap)
+		bcl->stats.sent_nacks++;
+	skb->priority = TC_PRIO_CONTROL;
+	__skb_queue_tail(xmitq, skb);
+	trace_tipc_proto_build(skb, false, l->name);
+}
+
+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_head *fdefq = &tnl->failover_deferdq;
+	struct sk_buff *skb, *tnlskb;
+	struct tipc_msg *hdr, tnlhdr;
+	struct sk_buff_head *queue = &l->transmq;
+	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);
+	/* 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),
+			      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);
+	if (mtyp == SYNCH_MSG)
+		pktcnt = l->snd_nxt - buf_seqno(skb_peek(&l->transmq));
+	else
+		pktcnt = skb_queue_len(&l->transmq);
+	pktcnt += 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);
+
+		/* 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) {
+			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;
+	}
+
+	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) {
+		tnl->drop_point = l->rcv_nxt;
+		tnl->failover_reasm_skb = l->reasm_buf;
+		l->reasm_buf = NULL;
+
+		/* Failover the link's deferdq */
+		if (unlikely(!skb_queue_empty(fdefq))) {
+			pr_warn("Link failover deferdq not empty: %d!\n",
+				skb_queue_len(fdefq));
+			__skb_queue_purge(fdefq);
+		}
+		skb_queue_splice_init(&l->deferdq, fdefq);
+	}
+}
+
+/**
+ * tipc_link_failover_prepare() - prepare tnl for link failover
+ *
+ * This is a special version of the precursor - tipc_link_tnl_prepare(),
+ * see the tipc_node_link_failover() for details
+ *
+ * @l: failover link
+ * @tnl: tunnel link
+ * @xmitq: queue for messages to be xmited
+ */
+void tipc_link_failover_prepare(struct tipc_link *l, struct tipc_link *tnl,
+				struct sk_buff_head *xmitq)
+{
+	struct sk_buff_head *fdefq = &tnl->failover_deferdq;
+
+	tipc_link_create_dummy_tnl_msg(tnl, xmitq);
+
+	/* 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
+	 * would have to start over from scratch instead.
+	 */
+	tnl->drop_point = 1;
+	tnl->failover_reasm_skb = NULL;
+
+	/* Initiate the link's failover deferdq */
+	if (unlikely(!skb_queue_empty(fdefq))) {
+		pr_warn("Link failover deferdq not empty: %d!\n",
+			skb_queue_len(fdefq));
+		__skb_queue_purge(fdefq);
+	}
+}
+
+/* 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);
+	struct tipc_gap_ack_blks *ga = NULL;
+	bool reply = msg_probe(hdr), retransmitted = false;
+	u32 dlen = msg_data_sz(hdr), glen = 0, msg_max;
+	u16 peers_snd_nxt =  msg_next_sent(hdr);
+	u16 peers_tol = msg_link_tolerance(hdr);
+	u16 peers_prio = msg_linkprio(hdr);
+	u16 gap = msg_seq_gap(hdr);
+	u16 ack = msg_ack(hdr);
+	u16 rcv_nxt = l->rcv_nxt;
+	u16 rcvgap = 0;
+	int mtyp = msg_type(hdr);
+	int rc = 0, released;
+	char *if_name;
+	void *data;
+
+	trace_tipc_proto_rcv(skb, false, l->name);
+
+	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);
+
+	if (skb_linearize(skb))
+		goto exit;
+
+	hdr = buf_msg(skb);
+	data = msg_data(hdr);
+
+	if (!tipc_link_validate_msg(l, hdr)) {
+		trace_tipc_skb_dump(skb, false, "PROTO invalid (1)!");
+		trace_tipc_link_dump(l, TIPC_DUMP_NONE, "PROTO invalid (1)!");
+		goto exit;
+	}
+
+	switch (mtyp) {
+	case RESET_MSG:
+	case ACTIVATE_MSG:
+		msg_max = msg_max_pkt(hdr);
+		if (msg_max < tipc_bearer_min_mtu(l->net, l->bearer_id))
+			break;
+		/* 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 (tipc_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 (tipc_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;
+		}
+
+		/* If this endpoint was re-created while peer was ESTABLISHING
+		 * it doesn't know current session number. Force re-synch.
+		 */
+		if (mtyp == ACTIVATE_MSG && msg_dest_session_valid(hdr) &&
+		    l->session != msg_dest_session(hdr)) {
+			if (less(l->session, msg_dest_session(hdr)))
+				l->session = msg_dest_session(hdr) + 1;
+			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)
+			l->mtu = msg_max;
+		break;
+
+	case STATE_MSG:
+		/* Validate Gap ACK blocks, drop if invalid */
+		glen = tipc_get_gap_ack_blks(&ga, l, hdr, true);
+		if (glen > dlen)
+			break;
+
+		l->rcv_nxt_state = msg_seqno(hdr) + 1;
+
+		/* Update own tolerance if peer indicates a non-zero value */
+		if (tipc_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) &&
+		    tipc_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 + glen, dlen - glen, l->addr,
+			     &l->mon_state, l->bearer_id);
+
+		/* Send NACK if peer has sent pkts we haven't received yet */
+		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);
+
+		released = tipc_link_advance_transmq(l, l, ack, gap, ga, xmitq,
+						     &retransmitted, &rc);
+		if (gap)
+			l->stats.recv_nacks++;
+		if (released || retransmitted)
+			tipc_link_update_cwin(l, released, retransmitted);
+		if (released)
+			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;
+}
+
+/* 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)
+{
+	u16 peers_snd_nxt = msg_bc_snd_nxt(hdr);
+	int rc = 0;
+
+	if (!link_is_up(l))
+		return rc;
+
+	if (!msg_peer_node_is_up(hdr))
+		return rc;
+
+	/* Open when peer acknowledges our bcast init msg (pkt #1) */
+	if (msg_ack(hdr))
+		l->bc_peer_is_up = true;
+
+	if (!l->bc_peer_is_up)
+		return rc;
+
+	/* Ignore if peers_snd_nxt goes beyond receive window */
+	if (more(peers_snd_nxt, l->rcv_nxt + l->window))
+		return rc;
+
+	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;
+}
+
+int tipc_link_bc_ack_rcv(struct tipc_link *r, u16 acked, u16 gap,
+			 struct tipc_gap_ack_blks *ga,
+			 struct sk_buff_head *xmitq,
+			 struct sk_buff_head *retrq)
+{
+	struct tipc_link *l = r->bc_sndlink;
+	bool unused = false;
+	int rc = 0;
+
+	if (!link_is_up(r) || !r->bc_peer_is_up)
+		return 0;
+
+	if (gap) {
+		l->stats.recv_nacks++;
+		r->stats.recv_nacks++;
+	}
+
+	if (less(acked, r->acked) || (acked == r->acked && !gap && !ga))
+		return 0;
+
+	trace_tipc_link_bc_ack(r, acked, gap, &l->transmq);
+	tipc_link_advance_transmq(l, r, acked, gap, ga, retrq, &unused, &rc);
+
+	tipc_link_advance_backlog(l, xmitq);
+	if (unlikely(!skb_queue_empty(&l->wakeupq)))
+		link_prepare_wakeup(l);
+
+	return rc;
+}
+
+/* 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)) {
+		rc = tipc_link_bc_ack_rcv(l, acked, to - acked, NULL, xmitq,
+					  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 min_win, u32 max_win)
+{
+	int max_bulk = TIPC_MAX_PUBL / (l->mtu / ITEM_SIZE);
+
+	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;
+}
+
+/**
+ * tipc_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_deprecated(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 max_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;
+	}
+
+	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_noflag(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_noflag(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_noflag(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_noflag(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,
+			struct tipc_link *bcl)
+{
+	int err;
+	void *hdr;
+	struct nlattr *attrs;
+	struct nlattr *prop;
+	u32 bc_mode = tipc_bcast_get_mode(net);
+	u32 bc_ratio = tipc_bcast_get_broadcast_ratio(net);
+
+	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_noflag(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_noflag(msg->skb, TIPC_NLA_LINK_PROP);
+	if (!prop)
+		goto attr_msg_full;
+	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;
+	if (bc_mode & BCLINK_MODE_SEL)
+		if (nla_put_u32(msg->skb, TIPC_NLA_PROP_BROADCAST_RATIO,
+				bc_ratio))
+			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;
+}
+
+/**
+ * tipc_link_dump - dump TIPC link data
+ * @l: tipc link to be dumped
+ * @dqueues: bitmask to decide if any link queue to be dumped?
+ *           - TIPC_DUMP_NONE: don't dump link queues
+ *           - TIPC_DUMP_TRANSMQ: dump link transmq queue
+ *           - TIPC_DUMP_BACKLOGQ: dump link backlog queue
+ *           - TIPC_DUMP_DEFERDQ: dump link deferd queue
+ *           - TIPC_DUMP_INPUTQ: dump link input queue
+ *           - TIPC_DUMP_WAKEUP: dump link wakeup queue
+ *           - TIPC_DUMP_ALL: dump all the link queues above
+ * @buf: returned buffer of dump data in format
+ */
+int tipc_link_dump(struct tipc_link *l, u16 dqueues, char *buf)
+{
+	int i = 0;
+	size_t sz = (dqueues) ? LINK_LMAX : LINK_LMIN;
+	struct sk_buff_head *list;
+	struct sk_buff *hskb, *tskb;
+	u32 len;
+
+	if (!l) {
+		i += scnprintf(buf, sz, "link data: (null)\n");
+		return i;
+	}
+
+	i += scnprintf(buf, sz, "link data: %x", l->addr);
+	i += scnprintf(buf + i, sz - i, " %x", l->state);
+	i += scnprintf(buf + i, sz - i, " %u", l->in_session);
+	i += scnprintf(buf + i, sz - i, " %u", l->session);
+	i += scnprintf(buf + i, sz - i, " %u", l->peer_session);
+	i += scnprintf(buf + i, sz - i, " %u", l->snd_nxt);
+	i += scnprintf(buf + i, sz - i, " %u", l->rcv_nxt);
+	i += scnprintf(buf + i, sz - i, " %u", l->snd_nxt_state);
+	i += scnprintf(buf + i, sz - i, " %u", l->rcv_nxt_state);
+	i += scnprintf(buf + i, sz - i, " %x", l->peer_caps);
+	i += scnprintf(buf + i, sz - i, " %u", l->silent_intv_cnt);
+	i += scnprintf(buf + i, sz - i, " %u", l->rst_cnt);
+	i += scnprintf(buf + i, sz - i, " %u", 0);
+	i += scnprintf(buf + i, sz - i, " %u", 0);
+	i += scnprintf(buf + i, sz - i, " %u", l->acked);
+
+	list = &l->transmq;
+	len = skb_queue_len(list);
+	hskb = skb_peek(list);
+	tskb = skb_peek_tail(list);
+	i += scnprintf(buf + i, sz - i, " | %u %u %u", len,
+		       (hskb) ? msg_seqno(buf_msg(hskb)) : 0,
+		       (tskb) ? msg_seqno(buf_msg(tskb)) : 0);
+
+	list = &l->deferdq;
+	len = skb_queue_len(list);
+	hskb = skb_peek(list);
+	tskb = skb_peek_tail(list);
+	i += scnprintf(buf + i, sz - i, " | %u %u %u", len,
+		       (hskb) ? msg_seqno(buf_msg(hskb)) : 0,
+		       (tskb) ? msg_seqno(buf_msg(tskb)) : 0);
+
+	list = &l->backlogq;
+	len = skb_queue_len(list);
+	hskb = skb_peek(list);
+	tskb = skb_peek_tail(list);
+	i += scnprintf(buf + i, sz - i, " | %u %u %u", len,
+		       (hskb) ? msg_seqno(buf_msg(hskb)) : 0,
+		       (tskb) ? msg_seqno(buf_msg(tskb)) : 0);
+
+	list = l->inputq;
+	len = skb_queue_len(list);
+	hskb = skb_peek(list);
+	tskb = skb_peek_tail(list);
+	i += scnprintf(buf + i, sz - i, " | %u %u %u\n", len,
+		       (hskb) ? msg_seqno(buf_msg(hskb)) : 0,
+		       (tskb) ? msg_seqno(buf_msg(tskb)) : 0);
+
+	if (dqueues & TIPC_DUMP_TRANSMQ) {
+		i += scnprintf(buf + i, sz - i, "transmq: ");
+		i += tipc_list_dump(&l->transmq, false, buf + i);
+	}
+	if (dqueues & TIPC_DUMP_BACKLOGQ) {
+		i += scnprintf(buf + i, sz - i,
+			       "backlogq: <%u %u %u %u %u>, ",
+			       l->backlog[TIPC_LOW_IMPORTANCE].len,
+			       l->backlog[TIPC_MEDIUM_IMPORTANCE].len,
+			       l->backlog[TIPC_HIGH_IMPORTANCE].len,
+			       l->backlog[TIPC_CRITICAL_IMPORTANCE].len,
+			       l->backlog[TIPC_SYSTEM_IMPORTANCE].len);
+		i += tipc_list_dump(&l->backlogq, false, buf + i);
+	}
+	if (dqueues & TIPC_DUMP_DEFERDQ) {
+		i += scnprintf(buf + i, sz - i, "deferdq: ");
+		i += tipc_list_dump(&l->deferdq, false, buf + i);
+	}
+	if (dqueues & TIPC_DUMP_INPUTQ) {
+		i += scnprintf(buf + i, sz - i, "inputq: ");
+		i += tipc_list_dump(l->inputq, false, buf + i);
+	}
+	if (dqueues & TIPC_DUMP_WAKEUP) {
+		i += scnprintf(buf + i, sz - i, "wakeup: ");
+		i += tipc_list_dump(&l->wakeupq, false, buf + i);
+	}
+
+	return i;
+}