text: /*
   * 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 <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
   * @prev_from: sequence number of most previous retransmission request
   * @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;
  	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;
  	} backlog[5];
  	u16 snd_nxt;
  	u16 prev_from;
  	u16 window;
  	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;
  	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))
  
  /*
   * 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);
  static u16 tipc_build_gap_ack_blks(struct tipc_link *l, void *data);
  static int tipc_link_advance_transmq(struct tipc_link *l, u16 acked, u16 gap,
  				     struct tipc_gap_ack_blks *ga,
  				     struct sk_buff_head *xmitq);
  
  /*
   *  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);
  	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;
  }
  
  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->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
   * @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);
  	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_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;
  	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;
  		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
   *
   * Returns 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);
  		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++;
  	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 *skb, *tmp;
  	int imp, i = 0;
  
  	skb_queue_walk_safe(&l->wakeupq, skb, tmp) {
  		imp = TIPC_SKB_CB(skb)->chain_imp;
  		if (l->backlog[imp].len < l->backlog[imp].limit) {
  			skb_unlink(skb, &l->wakeupq);
  			skb_queue_tail(l->inputq, skb);
  		} else if (i++ > 10) {
  			break;
  		}
  	}
  }
  
  void tipc_link_reset(struct tipc_link *l)
  {
  	struct sk_buff_head list;
  
  	__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);
  	l->backlog[TIPC_LOW_IMPORTANCE].len = 0;
  	l->backlog[TIPC_MEDIUM_IMPORTANCE].len = 0;
  	l->backlog[TIPC_HIGH_IMPORTANCE].len = 0;
  	l->backlog[TIPC_CRITICAL_IMPORTANCE].len = 0;
  	l->backlog[TIPC_SYSTEM_IMPORTANCE].len = 0;
  	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->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)
  {
  	struct tipc_msg *hdr = buf_msg(skb_peek(list));
  	unsigned int maxwin = l->window;
  	int imp = msg_importance(hdr);
  	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, *bskb;
  	int pkt_cnt = skb_queue_len(list);
  	int rc = 0;
  
  	if (unlikely(msg_size(hdr) > mtu)) {
  		skb_queue_purge(list);
  		return -EMSGSIZE;
  	}
  
  	/* 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);
  			/* next retransmit attempt */
  			if (link_is_bc_sndlink(l))
  				TIPC_SKB_CB(skb)->nxt_retr = TIPC_BC_RETR_LIM;
  			__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_bundle(skb_peek_tail(backlogq), hdr, mtu)) {
  			kfree_skb(__skb_dequeue(list));
  			l->stats.sent_bundled++;
  			continue;
  		}
  		if (tipc_msg_make_bundle(&bskb, hdr, mtu, l->addr)) {
  			kfree_skb(__skb_dequeue(list));
  			__skb_queue_tail(backlogq, bskb);
  			l->backlog[msg_importance(buf_msg(bskb))].len++;
  			l->stats.sent_bundled++;
  			l->stats.sent_bundles++;
  			continue;
  		}
  		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;
  
  	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);
  		l->backlog[msg_importance(hdr)].len--;
  		__skb_queue_tail(&l->transmq, skb);
  		/* next retransmit attempt */
  		if (link_is_bc_sndlink(l))
  			TIPC_SKB_CB(skb)->nxt_retr = TIPC_BC_RETR_LIM;
  
  		__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)
   * @from: seqno of the 1st packet in retransmit request
   * @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,
  				    u16 from, int *rc)
  {
  	struct sk_buff *skb = skb_peek(&l->transmq);
  	struct tipc_msg *hdr;
  
  	if (!skb)
  		return false;
  	hdr = buf_msg(skb);
  
  	/* Detect repeated retransmit failures on same packet */
  	if (r->prev_from != from) {
  		r->prev_from = from;
  		r->stale_limit = jiffies + msecs_to_jiffies(r->tolerance);
  	} else if (time_after(jiffies, r->stale_limit)) {
  		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));
  
  		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))
  			*rc = TIPC_LINK_DOWN_EVT;
  
  		*rc = tipc_link_fsm_evt(l, LINK_FAILURE_EVT);
  		return true;
  	}
  
  	return false;
  }
  
  /* tipc_link_bc_retrans() - retransmit zero 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_bc_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;
  	int rc = 0;
  
  	if (!skb)
  		return 0;
  	if (less(to, from))
  		return 0;
  
  	trace_tipc_link_retrans(r, from, to, &l->transmq);
  
  	if (link_retransmit_failure(l, r, from, &rc))
  		return rc;
  
  	skb_queue_walk(&l->transmq, skb) {
  		hdr = buf_msg(skb);
  		if (less(msg_seqno(hdr), from))
  			continue;
  		if (more(msg_seqno(hdr), to))
  			break;
  		if (link_is_bc_sndlink(l)) {
  			if (time_before(jiffies, TIPC_SKB_CB(skb)->nxt_retr))
  				continue;
  			TIPC_SKB_CB(skb)->nxt_retr = TIPC_BC_RETR_LIM;
  		}
  		_skb = __pskb_copy(skb, LL_MAX_HEADER + MIN_H_SIZE, GFP_ATOMIC);
  		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;
  		}
  		/* 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 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_head *fdefq = &l->failover_deferdq;
  	struct tipc_msg *hdr = buf_msg(skb);
  	struct sk_buff *iskb;
  	int ipos = 0;
  	int rc = 0;
  	u16 seqno;
  
  	/* SYNCH_MSG */
  	if (msg_type(hdr) == SYNCH_MSG)
  		goto drop;
  
  	/* FAILOVER_MSG */
  	if (!tipc_msg_extract(skb, &iskb, &ipos)) {
  		pr_warn_ratelimited("Cannot extract FAILOVER_MSG, defq: %d\n",
  				    skb_queue_len(fdefq));
  		return rc;
  	}
  
  	do {
  		seqno = buf_seqno(iskb);
  
  		if (unlikely(less(seqno, l->drop_point))) {
  			kfree_skb(iskb);
  			continue;
  		}
  
  		if (unlikely(seqno != l->drop_point)) {
  			__tipc_skb_queue_sorted(fdefq, seqno, iskb);
  			continue;
  		}
  
  		l->drop_point++;
  
  		if (!tipc_data_input(l, iskb, inputq))
  			rc |= tipc_link_input(l, iskb, inputq, reasm_skb);
  		if (unlikely(rc))
  			break;
  	} while ((iskb = __tipc_skb_dequeue(fdefq, l->drop_point)));
  
  drop:
  	kfree_skb(skb);
  	return rc;
  }
  
  static bool tipc_link_release_pkts(struct tipc_link *l, u16 acked)
  {
  	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_build_gap_ack_blks - build Gap ACK blocks
   * @l: tipc link that data have come with gaps in sequence if any
   * @data: data buffer to store the Gap ACK blocks after built
   *
   * returns the actual allocated memory size
   */
  static u16 tipc_build_gap_ack_blks(struct tipc_link *l, void *data)
  {
  	struct sk_buff *skb = skb_peek(&l->deferdq);
  	struct tipc_gap_ack_blks *ga = data;
  	u16 len, expect, seqno = 0;
  	u8 n = 0;
  
  	if (!skb)
  		goto exit;
  
  	expect = buf_seqno(skb);
  	skb_queue_walk(&l->deferdq, skb) {
  		seqno = buf_seqno(skb);
  		if (unlikely(more(seqno, expect))) {
  			ga->gacks[n].ack = htons(expect - 1);
  			ga->gacks[n].gap = htons(seqno - expect);
  			if (++n >= MAX_GAP_ACK_BLKS) {
  				pr_info_ratelimited("Too few Gap ACK blocks!\n");
  				goto exit;
  			}
  		} else if (unlikely(less(seqno, expect))) {
  			pr_warn("Unexpected skb in deferdq!\n");
  			continue;
  		}
  		expect = seqno + 1;
  	}
  
  	/* last block */
  	ga->gacks[n].ack = htons(seqno);
  	ga->gacks[n].gap = 0;
  	n++;
  
  exit:
  	len = tipc_gap_ack_blks_sz(n);
  	ga->len = htons(len);
  	ga->gack_cnt = n;
  	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
   * @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
   *
   * In case of a repeated retransmit failures, the call will return shortly
   * with a returned code (e.g. TIPC_LINK_DOWN_EVT)
   */
  static int tipc_link_advance_transmq(struct tipc_link *l, u16 acked, u16 gap,
  				     struct tipc_gap_ack_blks *ga,
  				     struct sk_buff_head *xmitq)
  {
  	struct sk_buff *skb, *_skb, *tmp;
  	struct tipc_msg *hdr;
  	u16 bc_ack = l->bc_rcvlink->rcv_nxt - 1;
  	u16 ack = l->rcv_nxt - 1;
  	u16 seqno, n = 0;
  	int rc = 0;
  
  	if (gap && link_retransmit_failure(l, l, acked + 1, &rc))
  		return rc;
  
  	skb_queue_walk_safe(&l->transmq, skb, tmp) {
  		seqno = buf_seqno(skb);
  
  next_gap_ack:
  		if (less_eq(seqno, acked)) {
  			/* release skb */
  			__skb_unlink(skb, &l->transmq);
  			kfree_skb(skb);
  		} else if (less_eq(seqno, acked + gap)) {
  			/* retransmit skb */
  			if (time_before(jiffies, TIPC_SKB_CB(skb)->nxt_retr))
  				continue;
  			TIPC_SKB_CB(skb)->nxt_retr = TIPC_UC_RETR_TIME;
  
  			_skb = __pskb_copy(skb, MIN_H_SIZE, 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++;
  		} else {
  			/* retry with Gap ACK blocks if any */
  			if (!ga || n >= ga->gack_cnt)
  				break;
  			acked = ntohs(ga->gacks[n].ack);
  			gap = ntohs(ga->gacks[n].gap);
  			n++;
  			goto next_gap_ack;
  		}
  	}
  
  	return 0;
  }
  
  /* 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;
  	u32 defq_len = skb_queue_len(&l->deferdq);
  	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))
  		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 = buf_msg(skb);
  	u16 seqno, rcv_nxt, win_lim;
  	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;
  			goto drop;
  		}
  
  		/* Drop if outside receive window */
  		if (unlikely(less(seqno, rcv_nxt) || more(seqno, win_lim))) {
  			l->stats.duplicates++;
  			goto drop;
  		}
  
  		/* Forward queues and wake up waiting users */
  		if (likely(tipc_link_release_pkts(l, msg_ack(hdr)))) {
  			tipc_link_advance_backlog(l, xmitq);
  			if (unlikely(!skb_queue_empty(&l->wakeupq)))
  				link_prepare_wakeup(l);
  		}
  
  		/* 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 (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)));
  
  	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;
  	u16 glen = 0;
  
  	/* 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 + 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);
  		msg_set_bc_gap(hdr, link_bc_rcv_gap(bcl));
  		msg_set_probe(hdr, probe);
  		msg_set_is_keepalive(hdr, probe || probe_reply);
  		if (l->peer_caps & TIPC_GAP_ACK_BLOCK)
  			glen = tipc_build_gap_ack_blks(l, data);
  		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++;
  	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;
  	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);
  	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);
  		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;
  
  		/* 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 enpoint 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;
  	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;
  	u16 dlen = msg_data_sz(hdr);
  	int mtyp = msg_type(hdr);
  	bool reply = msg_probe(hdr);
  	u16 glen = 0;
  	void *data;
  	char *if_name;
  	int rc = 0;
  
  	trace_tipc_proto_rcv(skb, false, l->name);
  	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)) {
  		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:
  		/* 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;
  		}
  
  		/* 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_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;
  		}
  
  		/* Receive Gap ACK blocks from peer if any */
  		if (l->peer_caps & TIPC_GAP_ACK_BLOCK) {
  			ga = (struct tipc_gap_ack_blks *)data;
  			glen = ntohs(ga->len);
  			/* sanity check: if failed, ignore Gap ACK blocks */
  			if (glen != tipc_gap_ack_blks_sz(ga->gack_cnt))
  				ga = NULL;
  		}
  
  		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 (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);
  
  		rc |= tipc_link_advance_transmq(l, ack, gap, ga, xmitq);
  
  		/* If NACK, retransmit will now start at right position */
  		if (gap)
  			l->stats.recv_nacks++;
  
  		tipc_link_advance_backlog(l, xmitq);
  		if (unlikely(!skb_queue_empty(&l->wakeupq)))
  			link_prepare_wakeup(l);
  	}
  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)
  {
  	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;
  
  	rc = tipc_link_bc_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;
  
  	trace_tipc_link_bc_ack(l, l->acked, acked, &snd_l->transmq);
  	/* 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_bc_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_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 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_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)
  {
  	int err;
  	void *hdr;
  	struct nlattr *attrs;
  	struct nlattr *prop;
  	struct tipc_net *tn = net_generic(net, tipc_net_id);
  	u32 bc_mode = tipc_bcast_get_broadcast_mode(net);
  	u32 bc_ratio = tipc_bcast_get_broadcast_ratio(net);
  	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_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->window))
  		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;
  }
  
  char *tipc_link_name_ext(struct tipc_link *l, char *buf)
  {
  	if (!l)
  		scnprintf(buf, TIPC_MAX_LINK_NAME, "null");
  	else if (link_is_bc_sndlink(l))
  		scnprintf(buf, TIPC_MAX_LINK_NAME, "broadcast-sender");
  	else if (link_is_bc_rcvlink(l))
  		scnprintf(buf, TIPC_MAX_LINK_NAME,
  			  "broadcast-receiver, peer %x", l->addr);
  	else
  		memcpy(buf, l->name, TIPC_MAX_LINK_NAME);
  
  	return buf;
  }
  
  /**
   * 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", l->prev_from);
  	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;
  }
  