xref: /linux/net/tipc/link.c (revision b2d0f5d5dc53532e6f07bc546a476a55ebdfe0f3)
1 /*
2  * net/tipc/link.c: TIPC link code
3  *
4  * Copyright (c) 1996-2007, 2012-2016, Ericsson AB
5  * Copyright (c) 2004-2007, 2010-2013, Wind River Systems
6  * All rights reserved.
7  *
8  * Redistribution and use in source and binary forms, with or without
9  * modification, are permitted provided that the following conditions are met:
10  *
11  * 1. Redistributions of source code must retain the above copyright
12  *    notice, this list of conditions and the following disclaimer.
13  * 2. Redistributions in binary form must reproduce the above copyright
14  *    notice, this list of conditions and the following disclaimer in the
15  *    documentation and/or other materials provided with the distribution.
16  * 3. Neither the names of the copyright holders nor the names of its
17  *    contributors may be used to endorse or promote products derived from
18  *    this software without specific prior written permission.
19  *
20  * Alternatively, this software may be distributed under the terms of the
21  * GNU General Public License ("GPL") version 2 as published by the Free
22  * Software Foundation.
23  *
24  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
25  * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
26  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
27  * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
28  * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
29  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
30  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
31  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
32  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
33  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
34  * POSSIBILITY OF SUCH DAMAGE.
35  */
36 
37 #include "core.h"
38 #include "subscr.h"
39 #include "link.h"
40 #include "bcast.h"
41 #include "socket.h"
42 #include "name_distr.h"
43 #include "discover.h"
44 #include "netlink.h"
45 #include "monitor.h"
46 
47 #include <linux/pkt_sched.h>
48 
49 struct tipc_stats {
50 	u32 sent_pkts;
51 	u32 recv_pkts;
52 	u32 sent_states;
53 	u32 recv_states;
54 	u32 sent_probes;
55 	u32 recv_probes;
56 	u32 sent_nacks;
57 	u32 recv_nacks;
58 	u32 sent_acks;
59 	u32 sent_bundled;
60 	u32 sent_bundles;
61 	u32 recv_bundled;
62 	u32 recv_bundles;
63 	u32 retransmitted;
64 	u32 sent_fragmented;
65 	u32 sent_fragments;
66 	u32 recv_fragmented;
67 	u32 recv_fragments;
68 	u32 link_congs;		/* # port sends blocked by congestion */
69 	u32 deferred_recv;
70 	u32 duplicates;
71 	u32 max_queue_sz;	/* send queue size high water mark */
72 	u32 accu_queue_sz;	/* used for send queue size profiling */
73 	u32 queue_sz_counts;	/* used for send queue size profiling */
74 	u32 msg_length_counts;	/* used for message length profiling */
75 	u32 msg_lengths_total;	/* used for message length profiling */
76 	u32 msg_length_profile[7]; /* used for msg. length profiling */
77 };
78 
79 /**
80  * struct tipc_link - TIPC link data structure
81  * @addr: network address of link's peer node
82  * @name: link name character string
83  * @media_addr: media address to use when sending messages over link
84  * @timer: link timer
85  * @net: pointer to namespace struct
86  * @refcnt: reference counter for permanent references (owner node & timer)
87  * @peer_session: link session # being used by peer end of link
88  * @peer_bearer_id: bearer id used by link's peer endpoint
89  * @bearer_id: local bearer id used by link
90  * @tolerance: minimum link continuity loss needed to reset link [in ms]
91  * @abort_limit: # of unacknowledged continuity probes needed to reset link
92  * @state: current state of link FSM
93  * @peer_caps: bitmap describing capabilities of peer node
94  * @silent_intv_cnt: # of timer intervals without any reception from peer
95  * @proto_msg: template for control messages generated by link
96  * @pmsg: convenience pointer to "proto_msg" field
97  * @priority: current link priority
98  * @net_plane: current link network plane ('A' through 'H')
99  * @mon_state: cookie with information needed by link monitor
100  * @backlog_limit: backlog queue congestion thresholds (indexed by importance)
101  * @exp_msg_count: # of tunnelled messages expected during link changeover
102  * @reset_rcv_checkpt: seq # of last acknowledged message at time of link reset
103  * @mtu: current maximum packet size for this link
104  * @advertised_mtu: advertised own mtu when link is being established
105  * @transmitq: queue for sent, non-acked messages
106  * @backlogq: queue for messages waiting to be sent
107  * @snt_nxt: next sequence number to use for outbound messages
108  * @last_retransmitted: sequence number of most recently retransmitted message
109  * @stale_count: # of identical retransmit requests made by peer
110  * @ackers: # of peers that needs to ack each packet before it can be released
111  * @acked: # last packet acked by a certain peer. Used for broadcast.
112  * @rcv_nxt: next sequence number to expect for inbound messages
113  * @deferred_queue: deferred queue saved OOS b'cast message received from node
114  * @unacked_window: # of inbound messages rx'd without ack'ing back to peer
115  * @inputq: buffer queue for messages to be delivered upwards
116  * @namedq: buffer queue for name table messages to be delivered upwards
117  * @next_out: ptr to first unsent outbound message in queue
118  * @wakeupq: linked list of wakeup msgs waiting for link congestion to abate
119  * @long_msg_seq_no: next identifier to use for outbound fragmented messages
120  * @reasm_buf: head of partially reassembled inbound message fragments
121  * @bc_rcvr: marks that this is a broadcast receiver link
122  * @stats: collects statistics regarding link activity
123  */
124 struct tipc_link {
125 	u32 addr;
126 	char name[TIPC_MAX_LINK_NAME];
127 	struct net *net;
128 
129 	/* Management and link supervision data */
130 	u32 peer_session;
131 	u32 session;
132 	u32 peer_bearer_id;
133 	u32 bearer_id;
134 	u32 tolerance;
135 	u32 abort_limit;
136 	u32 state;
137 	u16 peer_caps;
138 	bool active;
139 	u32 silent_intv_cnt;
140 	char if_name[TIPC_MAX_IF_NAME];
141 	u32 priority;
142 	char net_plane;
143 	struct tipc_mon_state mon_state;
144 	u16 rst_cnt;
145 
146 	/* Failover/synch */
147 	u16 drop_point;
148 	struct sk_buff *failover_reasm_skb;
149 
150 	/* Max packet negotiation */
151 	u16 mtu;
152 	u16 advertised_mtu;
153 
154 	/* Sending */
155 	struct sk_buff_head transmq;
156 	struct sk_buff_head backlogq;
157 	struct {
158 		u16 len;
159 		u16 limit;
160 	} backlog[5];
161 	u16 snd_nxt;
162 	u16 last_retransm;
163 	u16 window;
164 	u32 stale_count;
165 
166 	/* Reception */
167 	u16 rcv_nxt;
168 	u32 rcv_unacked;
169 	struct sk_buff_head deferdq;
170 	struct sk_buff_head *inputq;
171 	struct sk_buff_head *namedq;
172 
173 	/* Congestion handling */
174 	struct sk_buff_head wakeupq;
175 
176 	/* Fragmentation/reassembly */
177 	struct sk_buff *reasm_buf;
178 
179 	/* Broadcast */
180 	u16 ackers;
181 	u16 acked;
182 	struct tipc_link *bc_rcvlink;
183 	struct tipc_link *bc_sndlink;
184 	unsigned long prev_retr;
185 	u16 prev_from;
186 	u16 prev_to;
187 	u8 nack_state;
188 	bool bc_peer_is_up;
189 
190 	/* Statistics */
191 	struct tipc_stats stats;
192 };
193 
194 /*
195  * Error message prefixes
196  */
197 static const char *link_co_err = "Link tunneling error, ";
198 static const char *link_rst_msg = "Resetting link ";
199 
200 /* Send states for broadcast NACKs
201  */
202 enum {
203 	BC_NACK_SND_CONDITIONAL,
204 	BC_NACK_SND_UNCONDITIONAL,
205 	BC_NACK_SND_SUPPRESS,
206 };
207 
208 #define TIPC_BC_RETR_LIMIT 10   /* [ms] */
209 
210 /*
211  * Interval between NACKs when packets arrive out of order
212  */
213 #define TIPC_NACK_INTV (TIPC_MIN_LINK_WIN * 2)
214 
215 /* Wildcard value for link session numbers. When it is known that
216  * peer endpoint is down, any session number must be accepted.
217  */
218 #define ANY_SESSION 0x10000
219 
220 /* Link FSM states:
221  */
222 enum {
223 	LINK_ESTABLISHED     = 0xe,
224 	LINK_ESTABLISHING    = 0xe  << 4,
225 	LINK_RESET           = 0x1  << 8,
226 	LINK_RESETTING       = 0x2  << 12,
227 	LINK_PEER_RESET      = 0xd  << 16,
228 	LINK_FAILINGOVER     = 0xf  << 20,
229 	LINK_SYNCHING        = 0xc  << 24
230 };
231 
232 /* Link FSM state checking routines
233  */
234 static int link_is_up(struct tipc_link *l)
235 {
236 	return l->state & (LINK_ESTABLISHED | LINK_SYNCHING);
237 }
238 
239 static int tipc_link_proto_rcv(struct tipc_link *l, struct sk_buff *skb,
240 			       struct sk_buff_head *xmitq);
241 static void tipc_link_build_proto_msg(struct tipc_link *l, int mtyp, bool probe,
242 				      u16 rcvgap, int tolerance, int priority,
243 				      struct sk_buff_head *xmitq);
244 static void link_print(struct tipc_link *l, const char *str);
245 static int tipc_link_build_nack_msg(struct tipc_link *l,
246 				    struct sk_buff_head *xmitq);
247 static void tipc_link_build_bc_init_msg(struct tipc_link *l,
248 					struct sk_buff_head *xmitq);
249 static bool tipc_link_release_pkts(struct tipc_link *l, u16 to);
250 
251 /*
252  *  Simple non-static link routines (i.e. referenced outside this file)
253  */
254 bool tipc_link_is_up(struct tipc_link *l)
255 {
256 	return link_is_up(l);
257 }
258 
259 bool tipc_link_peer_is_down(struct tipc_link *l)
260 {
261 	return l->state == LINK_PEER_RESET;
262 }
263 
264 bool tipc_link_is_reset(struct tipc_link *l)
265 {
266 	return l->state & (LINK_RESET | LINK_FAILINGOVER | LINK_ESTABLISHING);
267 }
268 
269 bool tipc_link_is_establishing(struct tipc_link *l)
270 {
271 	return l->state == LINK_ESTABLISHING;
272 }
273 
274 bool tipc_link_is_synching(struct tipc_link *l)
275 {
276 	return l->state == LINK_SYNCHING;
277 }
278 
279 bool tipc_link_is_failingover(struct tipc_link *l)
280 {
281 	return l->state == LINK_FAILINGOVER;
282 }
283 
284 bool tipc_link_is_blocked(struct tipc_link *l)
285 {
286 	return l->state & (LINK_RESETTING | LINK_PEER_RESET | LINK_FAILINGOVER);
287 }
288 
289 static bool link_is_bc_sndlink(struct tipc_link *l)
290 {
291 	return !l->bc_sndlink;
292 }
293 
294 static bool link_is_bc_rcvlink(struct tipc_link *l)
295 {
296 	return ((l->bc_rcvlink == l) && !link_is_bc_sndlink(l));
297 }
298 
299 int tipc_link_is_active(struct tipc_link *l)
300 {
301 	return l->active;
302 }
303 
304 void tipc_link_set_active(struct tipc_link *l, bool active)
305 {
306 	l->active = active;
307 }
308 
309 u32 tipc_link_id(struct tipc_link *l)
310 {
311 	return l->peer_bearer_id << 16 | l->bearer_id;
312 }
313 
314 int tipc_link_window(struct tipc_link *l)
315 {
316 	return l->window;
317 }
318 
319 int tipc_link_prio(struct tipc_link *l)
320 {
321 	return l->priority;
322 }
323 
324 unsigned long tipc_link_tolerance(struct tipc_link *l)
325 {
326 	return l->tolerance;
327 }
328 
329 struct sk_buff_head *tipc_link_inputq(struct tipc_link *l)
330 {
331 	return l->inputq;
332 }
333 
334 char tipc_link_plane(struct tipc_link *l)
335 {
336 	return l->net_plane;
337 }
338 
339 void tipc_link_add_bc_peer(struct tipc_link *snd_l,
340 			   struct tipc_link *uc_l,
341 			   struct sk_buff_head *xmitq)
342 {
343 	struct tipc_link *rcv_l = uc_l->bc_rcvlink;
344 
345 	snd_l->ackers++;
346 	rcv_l->acked = snd_l->snd_nxt - 1;
347 	snd_l->state = LINK_ESTABLISHED;
348 	tipc_link_build_bc_init_msg(uc_l, xmitq);
349 }
350 
351 void tipc_link_remove_bc_peer(struct tipc_link *snd_l,
352 			      struct tipc_link *rcv_l,
353 			      struct sk_buff_head *xmitq)
354 {
355 	u16 ack = snd_l->snd_nxt - 1;
356 
357 	snd_l->ackers--;
358 	rcv_l->bc_peer_is_up = true;
359 	rcv_l->state = LINK_ESTABLISHED;
360 	tipc_link_bc_ack_rcv(rcv_l, ack, xmitq);
361 	tipc_link_reset(rcv_l);
362 	rcv_l->state = LINK_RESET;
363 	if (!snd_l->ackers) {
364 		tipc_link_reset(snd_l);
365 		snd_l->state = LINK_RESET;
366 		__skb_queue_purge(xmitq);
367 	}
368 }
369 
370 int tipc_link_bc_peers(struct tipc_link *l)
371 {
372 	return l->ackers;
373 }
374 
375 u16 link_bc_rcv_gap(struct tipc_link *l)
376 {
377 	struct sk_buff *skb = skb_peek(&l->deferdq);
378 	u16 gap = 0;
379 
380 	if (more(l->snd_nxt, l->rcv_nxt))
381 		gap = l->snd_nxt - l->rcv_nxt;
382 	if (skb)
383 		gap = buf_seqno(skb) - l->rcv_nxt;
384 	return gap;
385 }
386 
387 void tipc_link_set_mtu(struct tipc_link *l, int mtu)
388 {
389 	l->mtu = mtu;
390 }
391 
392 int tipc_link_mtu(struct tipc_link *l)
393 {
394 	return l->mtu;
395 }
396 
397 u16 tipc_link_rcv_nxt(struct tipc_link *l)
398 {
399 	return l->rcv_nxt;
400 }
401 
402 u16 tipc_link_acked(struct tipc_link *l)
403 {
404 	return l->acked;
405 }
406 
407 char *tipc_link_name(struct tipc_link *l)
408 {
409 	return l->name;
410 }
411 
412 /**
413  * tipc_link_create - create a new link
414  * @n: pointer to associated node
415  * @if_name: associated interface name
416  * @bearer_id: id (index) of associated bearer
417  * @tolerance: link tolerance to be used by link
418  * @net_plane: network plane (A,B,c..) this link belongs to
419  * @mtu: mtu to be advertised by link
420  * @priority: priority to be used by link
421  * @window: send window to be used by link
422  * @session: session to be used by link
423  * @ownnode: identity of own node
424  * @peer: node id of peer node
425  * @peer_caps: bitmap describing peer node capabilities
426  * @bc_sndlink: the namespace global link used for broadcast sending
427  * @bc_rcvlink: the peer specific link used for broadcast reception
428  * @inputq: queue to put messages ready for delivery
429  * @namedq: queue to put binding table update messages ready for delivery
430  * @link: return value, pointer to put the created link
431  *
432  * Returns true if link was created, otherwise false
433  */
434 bool tipc_link_create(struct net *net, char *if_name, int bearer_id,
435 		      int tolerance, char net_plane, u32 mtu, int priority,
436 		      int window, u32 session, u32 ownnode, u32 peer,
437 		      u16 peer_caps,
438 		      struct tipc_link *bc_sndlink,
439 		      struct tipc_link *bc_rcvlink,
440 		      struct sk_buff_head *inputq,
441 		      struct sk_buff_head *namedq,
442 		      struct tipc_link **link)
443 {
444 	struct tipc_link *l;
445 
446 	l = kzalloc(sizeof(*l), GFP_ATOMIC);
447 	if (!l)
448 		return false;
449 	*link = l;
450 	l->session = session;
451 
452 	/* Note: peer i/f name is completed by reset/activate message */
453 	sprintf(l->name, "%u.%u.%u:%s-%u.%u.%u:unknown",
454 		tipc_zone(ownnode), tipc_cluster(ownnode), tipc_node(ownnode),
455 		if_name, tipc_zone(peer), tipc_cluster(peer), tipc_node(peer));
456 	strcpy(l->if_name, if_name);
457 	l->addr = peer;
458 	l->peer_caps = peer_caps;
459 	l->net = net;
460 	l->peer_session = ANY_SESSION;
461 	l->bearer_id = bearer_id;
462 	l->tolerance = tolerance;
463 	l->net_plane = net_plane;
464 	l->advertised_mtu = mtu;
465 	l->mtu = mtu;
466 	l->priority = priority;
467 	tipc_link_set_queue_limits(l, window);
468 	l->ackers = 1;
469 	l->bc_sndlink = bc_sndlink;
470 	l->bc_rcvlink = bc_rcvlink;
471 	l->inputq = inputq;
472 	l->namedq = namedq;
473 	l->state = LINK_RESETTING;
474 	__skb_queue_head_init(&l->transmq);
475 	__skb_queue_head_init(&l->backlogq);
476 	__skb_queue_head_init(&l->deferdq);
477 	skb_queue_head_init(&l->wakeupq);
478 	skb_queue_head_init(l->inputq);
479 	return true;
480 }
481 
482 /**
483  * tipc_link_bc_create - create new link to be used for broadcast
484  * @n: pointer to associated node
485  * @mtu: mtu to be used
486  * @window: send window to be used
487  * @inputq: queue to put messages ready for delivery
488  * @namedq: queue to put binding table update messages ready for delivery
489  * @link: return value, pointer to put the created link
490  *
491  * Returns true if link was created, otherwise false
492  */
493 bool tipc_link_bc_create(struct net *net, u32 ownnode, u32 peer,
494 			 int mtu, int window, u16 peer_caps,
495 			 struct sk_buff_head *inputq,
496 			 struct sk_buff_head *namedq,
497 			 struct tipc_link *bc_sndlink,
498 			 struct tipc_link **link)
499 {
500 	struct tipc_link *l;
501 
502 	if (!tipc_link_create(net, "", MAX_BEARERS, 0, 'Z', mtu, 0, window,
503 			      0, ownnode, peer, peer_caps, bc_sndlink,
504 			      NULL, inputq, namedq, link))
505 		return false;
506 
507 	l = *link;
508 	strcpy(l->name, tipc_bclink_name);
509 	tipc_link_reset(l);
510 	l->state = LINK_RESET;
511 	l->ackers = 0;
512 	l->bc_rcvlink = l;
513 
514 	/* Broadcast send link is always up */
515 	if (link_is_bc_sndlink(l))
516 		l->state = LINK_ESTABLISHED;
517 
518 	/* Disable replicast if even a single peer doesn't support it */
519 	if (link_is_bc_rcvlink(l) && !(peer_caps & TIPC_BCAST_RCAST))
520 		tipc_bcast_disable_rcast(net);
521 
522 	return true;
523 }
524 
525 /**
526  * tipc_link_fsm_evt - link finite state machine
527  * @l: pointer to link
528  * @evt: state machine event to be processed
529  */
530 int tipc_link_fsm_evt(struct tipc_link *l, int evt)
531 {
532 	int rc = 0;
533 
534 	switch (l->state) {
535 	case LINK_RESETTING:
536 		switch (evt) {
537 		case LINK_PEER_RESET_EVT:
538 			l->state = LINK_PEER_RESET;
539 			break;
540 		case LINK_RESET_EVT:
541 			l->state = LINK_RESET;
542 			break;
543 		case LINK_FAILURE_EVT:
544 		case LINK_FAILOVER_BEGIN_EVT:
545 		case LINK_ESTABLISH_EVT:
546 		case LINK_FAILOVER_END_EVT:
547 		case LINK_SYNCH_BEGIN_EVT:
548 		case LINK_SYNCH_END_EVT:
549 		default:
550 			goto illegal_evt;
551 		}
552 		break;
553 	case LINK_RESET:
554 		switch (evt) {
555 		case LINK_PEER_RESET_EVT:
556 			l->state = LINK_ESTABLISHING;
557 			break;
558 		case LINK_FAILOVER_BEGIN_EVT:
559 			l->state = LINK_FAILINGOVER;
560 		case LINK_FAILURE_EVT:
561 		case LINK_RESET_EVT:
562 		case LINK_ESTABLISH_EVT:
563 		case LINK_FAILOVER_END_EVT:
564 			break;
565 		case LINK_SYNCH_BEGIN_EVT:
566 		case LINK_SYNCH_END_EVT:
567 		default:
568 			goto illegal_evt;
569 		}
570 		break;
571 	case LINK_PEER_RESET:
572 		switch (evt) {
573 		case LINK_RESET_EVT:
574 			l->state = LINK_ESTABLISHING;
575 			break;
576 		case LINK_PEER_RESET_EVT:
577 		case LINK_ESTABLISH_EVT:
578 		case LINK_FAILURE_EVT:
579 			break;
580 		case LINK_SYNCH_BEGIN_EVT:
581 		case LINK_SYNCH_END_EVT:
582 		case LINK_FAILOVER_BEGIN_EVT:
583 		case LINK_FAILOVER_END_EVT:
584 		default:
585 			goto illegal_evt;
586 		}
587 		break;
588 	case LINK_FAILINGOVER:
589 		switch (evt) {
590 		case LINK_FAILOVER_END_EVT:
591 			l->state = LINK_RESET;
592 			break;
593 		case LINK_PEER_RESET_EVT:
594 		case LINK_RESET_EVT:
595 		case LINK_ESTABLISH_EVT:
596 		case LINK_FAILURE_EVT:
597 			break;
598 		case LINK_FAILOVER_BEGIN_EVT:
599 		case LINK_SYNCH_BEGIN_EVT:
600 		case LINK_SYNCH_END_EVT:
601 		default:
602 			goto illegal_evt;
603 		}
604 		break;
605 	case LINK_ESTABLISHING:
606 		switch (evt) {
607 		case LINK_ESTABLISH_EVT:
608 			l->state = LINK_ESTABLISHED;
609 			break;
610 		case LINK_FAILOVER_BEGIN_EVT:
611 			l->state = LINK_FAILINGOVER;
612 			break;
613 		case LINK_RESET_EVT:
614 			l->state = LINK_RESET;
615 			break;
616 		case LINK_FAILURE_EVT:
617 		case LINK_PEER_RESET_EVT:
618 		case LINK_SYNCH_BEGIN_EVT:
619 		case LINK_FAILOVER_END_EVT:
620 			break;
621 		case LINK_SYNCH_END_EVT:
622 		default:
623 			goto illegal_evt;
624 		}
625 		break;
626 	case LINK_ESTABLISHED:
627 		switch (evt) {
628 		case LINK_PEER_RESET_EVT:
629 			l->state = LINK_PEER_RESET;
630 			rc |= TIPC_LINK_DOWN_EVT;
631 			break;
632 		case LINK_FAILURE_EVT:
633 			l->state = LINK_RESETTING;
634 			rc |= TIPC_LINK_DOWN_EVT;
635 			break;
636 		case LINK_RESET_EVT:
637 			l->state = LINK_RESET;
638 			break;
639 		case LINK_ESTABLISH_EVT:
640 		case LINK_SYNCH_END_EVT:
641 			break;
642 		case LINK_SYNCH_BEGIN_EVT:
643 			l->state = LINK_SYNCHING;
644 			break;
645 		case LINK_FAILOVER_BEGIN_EVT:
646 		case LINK_FAILOVER_END_EVT:
647 		default:
648 			goto illegal_evt;
649 		}
650 		break;
651 	case LINK_SYNCHING:
652 		switch (evt) {
653 		case LINK_PEER_RESET_EVT:
654 			l->state = LINK_PEER_RESET;
655 			rc |= TIPC_LINK_DOWN_EVT;
656 			break;
657 		case LINK_FAILURE_EVT:
658 			l->state = LINK_RESETTING;
659 			rc |= TIPC_LINK_DOWN_EVT;
660 			break;
661 		case LINK_RESET_EVT:
662 			l->state = LINK_RESET;
663 			break;
664 		case LINK_ESTABLISH_EVT:
665 		case LINK_SYNCH_BEGIN_EVT:
666 			break;
667 		case LINK_SYNCH_END_EVT:
668 			l->state = LINK_ESTABLISHED;
669 			break;
670 		case LINK_FAILOVER_BEGIN_EVT:
671 		case LINK_FAILOVER_END_EVT:
672 		default:
673 			goto illegal_evt;
674 		}
675 		break;
676 	default:
677 		pr_err("Unknown FSM state %x in %s\n", l->state, l->name);
678 	}
679 	return rc;
680 illegal_evt:
681 	pr_err("Illegal FSM event %x in state %x on link %s\n",
682 	       evt, l->state, l->name);
683 	return rc;
684 }
685 
686 /* link_profile_stats - update statistical profiling of traffic
687  */
688 static void link_profile_stats(struct tipc_link *l)
689 {
690 	struct sk_buff *skb;
691 	struct tipc_msg *msg;
692 	int length;
693 
694 	/* Update counters used in statistical profiling of send traffic */
695 	l->stats.accu_queue_sz += skb_queue_len(&l->transmq);
696 	l->stats.queue_sz_counts++;
697 
698 	skb = skb_peek(&l->transmq);
699 	if (!skb)
700 		return;
701 	msg = buf_msg(skb);
702 	length = msg_size(msg);
703 
704 	if (msg_user(msg) == MSG_FRAGMENTER) {
705 		if (msg_type(msg) != FIRST_FRAGMENT)
706 			return;
707 		length = msg_size(msg_get_wrapped(msg));
708 	}
709 	l->stats.msg_lengths_total += length;
710 	l->stats.msg_length_counts++;
711 	if (length <= 64)
712 		l->stats.msg_length_profile[0]++;
713 	else if (length <= 256)
714 		l->stats.msg_length_profile[1]++;
715 	else if (length <= 1024)
716 		l->stats.msg_length_profile[2]++;
717 	else if (length <= 4096)
718 		l->stats.msg_length_profile[3]++;
719 	else if (length <= 16384)
720 		l->stats.msg_length_profile[4]++;
721 	else if (length <= 32768)
722 		l->stats.msg_length_profile[5]++;
723 	else
724 		l->stats.msg_length_profile[6]++;
725 }
726 
727 /* tipc_link_timeout - perform periodic task as instructed from node timeout
728  */
729 int tipc_link_timeout(struct tipc_link *l, struct sk_buff_head *xmitq)
730 {
731 	int mtyp = 0;
732 	int rc = 0;
733 	bool state = false;
734 	bool probe = false;
735 	bool setup = false;
736 	u16 bc_snt = l->bc_sndlink->snd_nxt - 1;
737 	u16 bc_acked = l->bc_rcvlink->acked;
738 	struct tipc_mon_state *mstate = &l->mon_state;
739 
740 	switch (l->state) {
741 	case LINK_ESTABLISHED:
742 	case LINK_SYNCHING:
743 		mtyp = STATE_MSG;
744 		link_profile_stats(l);
745 		tipc_mon_get_state(l->net, l->addr, mstate, l->bearer_id);
746 		if (mstate->reset || (l->silent_intv_cnt > l->abort_limit))
747 			return tipc_link_fsm_evt(l, LINK_FAILURE_EVT);
748 		state = bc_acked != bc_snt;
749 		state |= l->bc_rcvlink->rcv_unacked;
750 		state |= l->rcv_unacked;
751 		state |= !skb_queue_empty(&l->transmq);
752 		state |= !skb_queue_empty(&l->deferdq);
753 		probe = mstate->probing;
754 		probe |= l->silent_intv_cnt;
755 		if (probe || mstate->monitoring)
756 			l->silent_intv_cnt++;
757 		break;
758 	case LINK_RESET:
759 		setup = l->rst_cnt++ <= 4;
760 		setup |= !(l->rst_cnt % 16);
761 		mtyp = RESET_MSG;
762 		break;
763 	case LINK_ESTABLISHING:
764 		setup = true;
765 		mtyp = ACTIVATE_MSG;
766 		break;
767 	case LINK_PEER_RESET:
768 	case LINK_RESETTING:
769 	case LINK_FAILINGOVER:
770 		break;
771 	default:
772 		break;
773 	}
774 
775 	if (state || probe || setup)
776 		tipc_link_build_proto_msg(l, mtyp, probe, 0, 0, 0, xmitq);
777 
778 	return rc;
779 }
780 
781 /**
782  * link_schedule_user - schedule a message sender for wakeup after congestion
783  * @l: congested link
784  * @hdr: header of message that is being sent
785  * Create pseudo msg to send back to user when congestion abates
786  */
787 static int link_schedule_user(struct tipc_link *l, struct tipc_msg *hdr)
788 {
789 	u32 dnode = tipc_own_addr(l->net);
790 	u32 dport = msg_origport(hdr);
791 	struct sk_buff *skb;
792 
793 	/* Create and schedule wakeup pseudo message */
794 	skb = tipc_msg_create(SOCK_WAKEUP, 0, INT_H_SIZE, 0,
795 			      dnode, l->addr, dport, 0, 0);
796 	if (!skb)
797 		return -ENOBUFS;
798 	msg_set_dest_droppable(buf_msg(skb), true);
799 	TIPC_SKB_CB(skb)->chain_imp = msg_importance(hdr);
800 	skb_queue_tail(&l->wakeupq, skb);
801 	l->stats.link_congs++;
802 	return -ELINKCONG;
803 }
804 
805 /**
806  * link_prepare_wakeup - prepare users for wakeup after congestion
807  * @l: congested link
808  * Wake up a number of waiting users, as permitted by available space
809  * in the send queue
810  */
811 void link_prepare_wakeup(struct tipc_link *l)
812 {
813 	struct sk_buff *skb, *tmp;
814 	int imp, i = 0;
815 
816 	skb_queue_walk_safe(&l->wakeupq, skb, tmp) {
817 		imp = TIPC_SKB_CB(skb)->chain_imp;
818 		if (l->backlog[imp].len < l->backlog[imp].limit) {
819 			skb_unlink(skb, &l->wakeupq);
820 			skb_queue_tail(l->inputq, skb);
821 		} else if (i++ > 10) {
822 			break;
823 		}
824 	}
825 }
826 
827 void tipc_link_reset(struct tipc_link *l)
828 {
829 	l->peer_session = ANY_SESSION;
830 	l->session++;
831 	l->mtu = l->advertised_mtu;
832 	__skb_queue_purge(&l->transmq);
833 	__skb_queue_purge(&l->deferdq);
834 	skb_queue_splice_init(&l->wakeupq, l->inputq);
835 	__skb_queue_purge(&l->backlogq);
836 	l->backlog[TIPC_LOW_IMPORTANCE].len = 0;
837 	l->backlog[TIPC_MEDIUM_IMPORTANCE].len = 0;
838 	l->backlog[TIPC_HIGH_IMPORTANCE].len = 0;
839 	l->backlog[TIPC_CRITICAL_IMPORTANCE].len = 0;
840 	l->backlog[TIPC_SYSTEM_IMPORTANCE].len = 0;
841 	kfree_skb(l->reasm_buf);
842 	kfree_skb(l->failover_reasm_skb);
843 	l->reasm_buf = NULL;
844 	l->failover_reasm_skb = NULL;
845 	l->rcv_unacked = 0;
846 	l->snd_nxt = 1;
847 	l->rcv_nxt = 1;
848 	l->acked = 0;
849 	l->silent_intv_cnt = 0;
850 	l->rst_cnt = 0;
851 	l->stale_count = 0;
852 	l->bc_peer_is_up = false;
853 	memset(&l->mon_state, 0, sizeof(l->mon_state));
854 	tipc_link_reset_stats(l);
855 }
856 
857 /**
858  * tipc_link_xmit(): enqueue buffer list according to queue situation
859  * @link: link to use
860  * @list: chain of buffers containing message
861  * @xmitq: returned list of packets to be sent by caller
862  *
863  * Consumes the buffer chain.
864  * Returns 0 if success, or errno: -ELINKCONG, -EMSGSIZE or -ENOBUFS
865  * Messages at TIPC_SYSTEM_IMPORTANCE are always accepted
866  */
867 int tipc_link_xmit(struct tipc_link *l, struct sk_buff_head *list,
868 		   struct sk_buff_head *xmitq)
869 {
870 	struct tipc_msg *hdr = buf_msg(skb_peek(list));
871 	unsigned int maxwin = l->window;
872 	int imp = msg_importance(hdr);
873 	unsigned int mtu = l->mtu;
874 	u16 ack = l->rcv_nxt - 1;
875 	u16 seqno = l->snd_nxt;
876 	u16 bc_ack = l->bc_rcvlink->rcv_nxt - 1;
877 	struct sk_buff_head *transmq = &l->transmq;
878 	struct sk_buff_head *backlogq = &l->backlogq;
879 	struct sk_buff *skb, *_skb, *bskb;
880 	int pkt_cnt = skb_queue_len(list);
881 	int rc = 0;
882 
883 	if (unlikely(msg_size(hdr) > mtu)) {
884 		skb_queue_purge(list);
885 		return -EMSGSIZE;
886 	}
887 
888 	/* Allow oversubscription of one data msg per source at congestion */
889 	if (unlikely(l->backlog[imp].len >= l->backlog[imp].limit)) {
890 		if (imp == TIPC_SYSTEM_IMPORTANCE) {
891 			pr_warn("%s<%s>, link overflow", link_rst_msg, l->name);
892 			return -ENOBUFS;
893 		}
894 		rc = link_schedule_user(l, hdr);
895 	}
896 
897 	if (pkt_cnt > 1) {
898 		l->stats.sent_fragmented++;
899 		l->stats.sent_fragments += pkt_cnt;
900 	}
901 
902 	/* Prepare each packet for sending, and add to relevant queue: */
903 	while (skb_queue_len(list)) {
904 		skb = skb_peek(list);
905 		hdr = buf_msg(skb);
906 		msg_set_seqno(hdr, seqno);
907 		msg_set_ack(hdr, ack);
908 		msg_set_bcast_ack(hdr, bc_ack);
909 
910 		if (likely(skb_queue_len(transmq) < maxwin)) {
911 			_skb = skb_clone(skb, GFP_ATOMIC);
912 			if (!_skb) {
913 				skb_queue_purge(list);
914 				return -ENOBUFS;
915 			}
916 			__skb_dequeue(list);
917 			__skb_queue_tail(transmq, skb);
918 			__skb_queue_tail(xmitq, _skb);
919 			TIPC_SKB_CB(skb)->ackers = l->ackers;
920 			l->rcv_unacked = 0;
921 			l->stats.sent_pkts++;
922 			seqno++;
923 			continue;
924 		}
925 		if (tipc_msg_bundle(skb_peek_tail(backlogq), hdr, mtu)) {
926 			kfree_skb(__skb_dequeue(list));
927 			l->stats.sent_bundled++;
928 			continue;
929 		}
930 		if (tipc_msg_make_bundle(&bskb, hdr, mtu, l->addr)) {
931 			kfree_skb(__skb_dequeue(list));
932 			__skb_queue_tail(backlogq, bskb);
933 			l->backlog[msg_importance(buf_msg(bskb))].len++;
934 			l->stats.sent_bundled++;
935 			l->stats.sent_bundles++;
936 			continue;
937 		}
938 		l->backlog[imp].len += skb_queue_len(list);
939 		skb_queue_splice_tail_init(list, backlogq);
940 	}
941 	l->snd_nxt = seqno;
942 	return rc;
943 }
944 
945 void tipc_link_advance_backlog(struct tipc_link *l, struct sk_buff_head *xmitq)
946 {
947 	struct sk_buff *skb, *_skb;
948 	struct tipc_msg *hdr;
949 	u16 seqno = l->snd_nxt;
950 	u16 ack = l->rcv_nxt - 1;
951 	u16 bc_ack = l->bc_rcvlink->rcv_nxt - 1;
952 
953 	while (skb_queue_len(&l->transmq) < l->window) {
954 		skb = skb_peek(&l->backlogq);
955 		if (!skb)
956 			break;
957 		_skb = skb_clone(skb, GFP_ATOMIC);
958 		if (!_skb)
959 			break;
960 		__skb_dequeue(&l->backlogq);
961 		hdr = buf_msg(skb);
962 		l->backlog[msg_importance(hdr)].len--;
963 		__skb_queue_tail(&l->transmq, skb);
964 		__skb_queue_tail(xmitq, _skb);
965 		TIPC_SKB_CB(skb)->ackers = l->ackers;
966 		msg_set_seqno(hdr, seqno);
967 		msg_set_ack(hdr, ack);
968 		msg_set_bcast_ack(hdr, bc_ack);
969 		l->rcv_unacked = 0;
970 		l->stats.sent_pkts++;
971 		seqno++;
972 	}
973 	l->snd_nxt = seqno;
974 }
975 
976 static void link_retransmit_failure(struct tipc_link *l, struct sk_buff *skb)
977 {
978 	struct tipc_msg *hdr = buf_msg(skb);
979 
980 	pr_warn("Retransmission failure on link <%s>\n", l->name);
981 	link_print(l, "State of link ");
982 	pr_info("Failed msg: usr %u, typ %u, len %u, err %u\n",
983 		msg_user(hdr), msg_type(hdr), msg_size(hdr), msg_errcode(hdr));
984 	pr_info("sqno %u, prev: %x, src: %x\n",
985 		msg_seqno(hdr), msg_prevnode(hdr), msg_orignode(hdr));
986 }
987 
988 int tipc_link_retrans(struct tipc_link *l, struct tipc_link *nacker,
989 		      u16 from, u16 to, struct sk_buff_head *xmitq)
990 {
991 	struct sk_buff *_skb, *skb = skb_peek(&l->transmq);
992 	struct tipc_msg *hdr;
993 	u16 ack = l->rcv_nxt - 1;
994 	u16 bc_ack = l->bc_rcvlink->rcv_nxt - 1;
995 
996 	if (!skb)
997 		return 0;
998 
999 	/* Detect repeated retransmit failures on same packet */
1000 	if (nacker->last_retransm != buf_seqno(skb)) {
1001 		nacker->last_retransm = buf_seqno(skb);
1002 		nacker->stale_count = 1;
1003 	} else if (++nacker->stale_count > 100) {
1004 		link_retransmit_failure(l, skb);
1005 		nacker->stale_count = 0;
1006 		if (link_is_bc_sndlink(l))
1007 			return TIPC_LINK_DOWN_EVT;
1008 		return tipc_link_fsm_evt(l, LINK_FAILURE_EVT);
1009 	}
1010 
1011 	/* Move forward to where retransmission should start */
1012 	skb_queue_walk(&l->transmq, skb) {
1013 		if (!less(buf_seqno(skb), from))
1014 			break;
1015 	}
1016 
1017 	skb_queue_walk_from(&l->transmq, skb) {
1018 		if (more(buf_seqno(skb), to))
1019 			break;
1020 		hdr = buf_msg(skb);
1021 		_skb = __pskb_copy(skb, MIN_H_SIZE, GFP_ATOMIC);
1022 		if (!_skb)
1023 			return 0;
1024 		hdr = buf_msg(_skb);
1025 		msg_set_ack(hdr, ack);
1026 		msg_set_bcast_ack(hdr, bc_ack);
1027 		_skb->priority = TC_PRIO_CONTROL;
1028 		__skb_queue_tail(xmitq, _skb);
1029 		l->stats.retransmitted++;
1030 	}
1031 	return 0;
1032 }
1033 
1034 /* tipc_data_input - deliver data and name distr msgs to upper layer
1035  *
1036  * Consumes buffer if message is of right type
1037  * Node lock must be held
1038  */
1039 static bool tipc_data_input(struct tipc_link *l, struct sk_buff *skb,
1040 			    struct sk_buff_head *inputq)
1041 {
1042 	struct sk_buff_head *mc_inputq = l->bc_rcvlink->inputq;
1043 	struct tipc_msg *hdr = buf_msg(skb);
1044 
1045 	switch (msg_user(hdr)) {
1046 	case TIPC_LOW_IMPORTANCE:
1047 	case TIPC_MEDIUM_IMPORTANCE:
1048 	case TIPC_HIGH_IMPORTANCE:
1049 	case TIPC_CRITICAL_IMPORTANCE:
1050 		if (unlikely(msg_in_group(hdr) || msg_mcast(hdr))) {
1051 			skb_queue_tail(mc_inputq, skb);
1052 			return true;
1053 		}
1054 	case CONN_MANAGER:
1055 		skb_queue_tail(inputq, skb);
1056 		return true;
1057 	case GROUP_PROTOCOL:
1058 		skb_queue_tail(mc_inputq, skb);
1059 		return true;
1060 	case NAME_DISTRIBUTOR:
1061 		l->bc_rcvlink->state = LINK_ESTABLISHED;
1062 		skb_queue_tail(l->namedq, skb);
1063 		return true;
1064 	case MSG_BUNDLER:
1065 	case TUNNEL_PROTOCOL:
1066 	case MSG_FRAGMENTER:
1067 	case BCAST_PROTOCOL:
1068 		return false;
1069 	default:
1070 		pr_warn("Dropping received illegal msg type\n");
1071 		kfree_skb(skb);
1072 		return false;
1073 	};
1074 }
1075 
1076 /* tipc_link_input - process packet that has passed link protocol check
1077  *
1078  * Consumes buffer
1079  */
1080 static int tipc_link_input(struct tipc_link *l, struct sk_buff *skb,
1081 			   struct sk_buff_head *inputq)
1082 {
1083 	struct tipc_msg *hdr = buf_msg(skb);
1084 	struct sk_buff **reasm_skb = &l->reasm_buf;
1085 	struct sk_buff *iskb;
1086 	struct sk_buff_head tmpq;
1087 	int usr = msg_user(hdr);
1088 	int rc = 0;
1089 	int pos = 0;
1090 	int ipos = 0;
1091 
1092 	if (unlikely(usr == TUNNEL_PROTOCOL)) {
1093 		if (msg_type(hdr) == SYNCH_MSG) {
1094 			__skb_queue_purge(&l->deferdq);
1095 			goto drop;
1096 		}
1097 		if (!tipc_msg_extract(skb, &iskb, &ipos))
1098 			return rc;
1099 		kfree_skb(skb);
1100 		skb = iskb;
1101 		hdr = buf_msg(skb);
1102 		if (less(msg_seqno(hdr), l->drop_point))
1103 			goto drop;
1104 		if (tipc_data_input(l, skb, inputq))
1105 			return rc;
1106 		usr = msg_user(hdr);
1107 		reasm_skb = &l->failover_reasm_skb;
1108 	}
1109 
1110 	if (usr == MSG_BUNDLER) {
1111 		skb_queue_head_init(&tmpq);
1112 		l->stats.recv_bundles++;
1113 		l->stats.recv_bundled += msg_msgcnt(hdr);
1114 		while (tipc_msg_extract(skb, &iskb, &pos))
1115 			tipc_data_input(l, iskb, &tmpq);
1116 		tipc_skb_queue_splice_tail(&tmpq, inputq);
1117 		return 0;
1118 	} else if (usr == MSG_FRAGMENTER) {
1119 		l->stats.recv_fragments++;
1120 		if (tipc_buf_append(reasm_skb, &skb)) {
1121 			l->stats.recv_fragmented++;
1122 			tipc_data_input(l, skb, inputq);
1123 		} else if (!*reasm_skb && !link_is_bc_rcvlink(l)) {
1124 			pr_warn_ratelimited("Unable to build fragment list\n");
1125 			return tipc_link_fsm_evt(l, LINK_FAILURE_EVT);
1126 		}
1127 		return 0;
1128 	} else if (usr == BCAST_PROTOCOL) {
1129 		tipc_bcast_lock(l->net);
1130 		tipc_link_bc_init_rcv(l->bc_rcvlink, hdr);
1131 		tipc_bcast_unlock(l->net);
1132 	}
1133 drop:
1134 	kfree_skb(skb);
1135 	return 0;
1136 }
1137 
1138 static bool tipc_link_release_pkts(struct tipc_link *l, u16 acked)
1139 {
1140 	bool released = false;
1141 	struct sk_buff *skb, *tmp;
1142 
1143 	skb_queue_walk_safe(&l->transmq, skb, tmp) {
1144 		if (more(buf_seqno(skb), acked))
1145 			break;
1146 		__skb_unlink(skb, &l->transmq);
1147 		kfree_skb(skb);
1148 		released = true;
1149 	}
1150 	return released;
1151 }
1152 
1153 /* tipc_link_build_state_msg: prepare link state message for transmission
1154  *
1155  * Note that sending of broadcast ack is coordinated among nodes, to reduce
1156  * risk of ack storms towards the sender
1157  */
1158 int tipc_link_build_state_msg(struct tipc_link *l, struct sk_buff_head *xmitq)
1159 {
1160 	if (!l)
1161 		return 0;
1162 
1163 	/* Broadcast ACK must be sent via a unicast link => defer to caller */
1164 	if (link_is_bc_rcvlink(l)) {
1165 		if (((l->rcv_nxt ^ tipc_own_addr(l->net)) & 0xf) != 0xf)
1166 			return 0;
1167 		l->rcv_unacked = 0;
1168 
1169 		/* Use snd_nxt to store peer's snd_nxt in broadcast rcv link */
1170 		l->snd_nxt = l->rcv_nxt;
1171 		return TIPC_LINK_SND_STATE;
1172 	}
1173 
1174 	/* Unicast ACK */
1175 	l->rcv_unacked = 0;
1176 	l->stats.sent_acks++;
1177 	tipc_link_build_proto_msg(l, STATE_MSG, 0, 0, 0, 0, xmitq);
1178 	return 0;
1179 }
1180 
1181 /* tipc_link_build_reset_msg: prepare link RESET or ACTIVATE message
1182  */
1183 void tipc_link_build_reset_msg(struct tipc_link *l, struct sk_buff_head *xmitq)
1184 {
1185 	int mtyp = RESET_MSG;
1186 	struct sk_buff *skb;
1187 
1188 	if (l->state == LINK_ESTABLISHING)
1189 		mtyp = ACTIVATE_MSG;
1190 
1191 	tipc_link_build_proto_msg(l, mtyp, 0, 0, 0, 0, xmitq);
1192 
1193 	/* Inform peer that this endpoint is going down if applicable */
1194 	skb = skb_peek_tail(xmitq);
1195 	if (skb && (l->state == LINK_RESET))
1196 		msg_set_peer_stopping(buf_msg(skb), 1);
1197 }
1198 
1199 /* tipc_link_build_nack_msg: prepare link nack message for transmission
1200  * Note that sending of broadcast NACK is coordinated among nodes, to
1201  * reduce the risk of NACK storms towards the sender
1202  */
1203 static int tipc_link_build_nack_msg(struct tipc_link *l,
1204 				    struct sk_buff_head *xmitq)
1205 {
1206 	u32 def_cnt = ++l->stats.deferred_recv;
1207 	int match1, match2;
1208 
1209 	if (link_is_bc_rcvlink(l)) {
1210 		match1 = def_cnt & 0xf;
1211 		match2 = tipc_own_addr(l->net) & 0xf;
1212 		if (match1 == match2)
1213 			return TIPC_LINK_SND_STATE;
1214 		return 0;
1215 	}
1216 
1217 	if ((skb_queue_len(&l->deferdq) == 1) || !(def_cnt % TIPC_NACK_INTV))
1218 		tipc_link_build_proto_msg(l, STATE_MSG, 0, 0, 0, 0, xmitq);
1219 	return 0;
1220 }
1221 
1222 /* tipc_link_rcv - process TIPC packets/messages arriving from off-node
1223  * @l: the link that should handle the message
1224  * @skb: TIPC packet
1225  * @xmitq: queue to place packets to be sent after this call
1226  */
1227 int tipc_link_rcv(struct tipc_link *l, struct sk_buff *skb,
1228 		  struct sk_buff_head *xmitq)
1229 {
1230 	struct sk_buff_head *defq = &l->deferdq;
1231 	struct tipc_msg *hdr;
1232 	u16 seqno, rcv_nxt, win_lim;
1233 	int rc = 0;
1234 
1235 	do {
1236 		hdr = buf_msg(skb);
1237 		seqno = msg_seqno(hdr);
1238 		rcv_nxt = l->rcv_nxt;
1239 		win_lim = rcv_nxt + TIPC_MAX_LINK_WIN;
1240 
1241 		/* Verify and update link state */
1242 		if (unlikely(msg_user(hdr) == LINK_PROTOCOL))
1243 			return tipc_link_proto_rcv(l, skb, xmitq);
1244 
1245 		if (unlikely(!link_is_up(l))) {
1246 			if (l->state == LINK_ESTABLISHING)
1247 				rc = TIPC_LINK_UP_EVT;
1248 			goto drop;
1249 		}
1250 
1251 		/* Don't send probe at next timeout expiration */
1252 		l->silent_intv_cnt = 0;
1253 
1254 		/* Drop if outside receive window */
1255 		if (unlikely(less(seqno, rcv_nxt) || more(seqno, win_lim))) {
1256 			l->stats.duplicates++;
1257 			goto drop;
1258 		}
1259 
1260 		/* Forward queues and wake up waiting users */
1261 		if (likely(tipc_link_release_pkts(l, msg_ack(hdr)))) {
1262 			tipc_link_advance_backlog(l, xmitq);
1263 			if (unlikely(!skb_queue_empty(&l->wakeupq)))
1264 				link_prepare_wakeup(l);
1265 		}
1266 
1267 		/* Defer delivery if sequence gap */
1268 		if (unlikely(seqno != rcv_nxt)) {
1269 			__tipc_skb_queue_sorted(defq, seqno, skb);
1270 			rc |= tipc_link_build_nack_msg(l, xmitq);
1271 			break;
1272 		}
1273 
1274 		/* Deliver packet */
1275 		l->rcv_nxt++;
1276 		l->stats.recv_pkts++;
1277 		if (!tipc_data_input(l, skb, l->inputq))
1278 			rc |= tipc_link_input(l, skb, l->inputq);
1279 		if (unlikely(++l->rcv_unacked >= TIPC_MIN_LINK_WIN))
1280 			rc |= tipc_link_build_state_msg(l, xmitq);
1281 		if (unlikely(rc & ~TIPC_LINK_SND_STATE))
1282 			break;
1283 	} while ((skb = __skb_dequeue(defq)));
1284 
1285 	return rc;
1286 drop:
1287 	kfree_skb(skb);
1288 	return rc;
1289 }
1290 
1291 static void tipc_link_build_proto_msg(struct tipc_link *l, int mtyp, bool probe,
1292 				      u16 rcvgap, int tolerance, int priority,
1293 				      struct sk_buff_head *xmitq)
1294 {
1295 	struct tipc_link *bcl = l->bc_rcvlink;
1296 	struct sk_buff *skb;
1297 	struct tipc_msg *hdr;
1298 	struct sk_buff_head *dfq = &l->deferdq;
1299 	bool node_up = link_is_up(bcl);
1300 	struct tipc_mon_state *mstate = &l->mon_state;
1301 	int dlen = 0;
1302 	void *data;
1303 
1304 	/* Don't send protocol message during reset or link failover */
1305 	if (tipc_link_is_blocked(l))
1306 		return;
1307 
1308 	if (!tipc_link_is_up(l) && (mtyp == STATE_MSG))
1309 		return;
1310 
1311 	if (!skb_queue_empty(dfq))
1312 		rcvgap = buf_seqno(skb_peek(dfq)) - l->rcv_nxt;
1313 
1314 	skb = tipc_msg_create(LINK_PROTOCOL, mtyp, INT_H_SIZE,
1315 			      tipc_max_domain_size, l->addr,
1316 			      tipc_own_addr(l->net), 0, 0, 0);
1317 	if (!skb)
1318 		return;
1319 
1320 	hdr = buf_msg(skb);
1321 	data = msg_data(hdr);
1322 	msg_set_session(hdr, l->session);
1323 	msg_set_bearer_id(hdr, l->bearer_id);
1324 	msg_set_net_plane(hdr, l->net_plane);
1325 	msg_set_next_sent(hdr, l->snd_nxt);
1326 	msg_set_ack(hdr, l->rcv_nxt - 1);
1327 	msg_set_bcast_ack(hdr, bcl->rcv_nxt - 1);
1328 	msg_set_bc_ack_invalid(hdr, !node_up);
1329 	msg_set_last_bcast(hdr, l->bc_sndlink->snd_nxt - 1);
1330 	msg_set_link_tolerance(hdr, tolerance);
1331 	msg_set_linkprio(hdr, priority);
1332 	msg_set_redundant_link(hdr, node_up);
1333 	msg_set_seq_gap(hdr, 0);
1334 	msg_set_seqno(hdr, l->snd_nxt + U16_MAX / 2);
1335 
1336 	if (mtyp == STATE_MSG) {
1337 		msg_set_seq_gap(hdr, rcvgap);
1338 		msg_set_bc_gap(hdr, link_bc_rcv_gap(bcl));
1339 		msg_set_probe(hdr, probe);
1340 		tipc_mon_prep(l->net, data, &dlen, mstate, l->bearer_id);
1341 		msg_set_size(hdr, INT_H_SIZE + dlen);
1342 		skb_trim(skb, INT_H_SIZE + dlen);
1343 		l->stats.sent_states++;
1344 		l->rcv_unacked = 0;
1345 	} else {
1346 		/* RESET_MSG or ACTIVATE_MSG */
1347 		msg_set_max_pkt(hdr, l->advertised_mtu);
1348 		strcpy(data, l->if_name);
1349 		msg_set_size(hdr, INT_H_SIZE + TIPC_MAX_IF_NAME);
1350 		skb_trim(skb, INT_H_SIZE + TIPC_MAX_IF_NAME);
1351 	}
1352 	if (probe)
1353 		l->stats.sent_probes++;
1354 	if (rcvgap)
1355 		l->stats.sent_nacks++;
1356 	skb->priority = TC_PRIO_CONTROL;
1357 	__skb_queue_tail(xmitq, skb);
1358 }
1359 
1360 /* tipc_link_tnl_prepare(): prepare and return a list of tunnel packets
1361  * with contents of the link's transmit and backlog queues.
1362  */
1363 void tipc_link_tnl_prepare(struct tipc_link *l, struct tipc_link *tnl,
1364 			   int mtyp, struct sk_buff_head *xmitq)
1365 {
1366 	struct sk_buff *skb, *tnlskb;
1367 	struct tipc_msg *hdr, tnlhdr;
1368 	struct sk_buff_head *queue = &l->transmq;
1369 	struct sk_buff_head tmpxq, tnlq;
1370 	u16 pktlen, pktcnt, seqno = l->snd_nxt;
1371 
1372 	if (!tnl)
1373 		return;
1374 
1375 	skb_queue_head_init(&tnlq);
1376 	skb_queue_head_init(&tmpxq);
1377 
1378 	/* At least one packet required for safe algorithm => add dummy */
1379 	skb = tipc_msg_create(TIPC_LOW_IMPORTANCE, TIPC_DIRECT_MSG,
1380 			      BASIC_H_SIZE, 0, l->addr, tipc_own_addr(l->net),
1381 			      0, 0, TIPC_ERR_NO_PORT);
1382 	if (!skb) {
1383 		pr_warn("%sunable to create tunnel packet\n", link_co_err);
1384 		return;
1385 	}
1386 	skb_queue_tail(&tnlq, skb);
1387 	tipc_link_xmit(l, &tnlq, &tmpxq);
1388 	__skb_queue_purge(&tmpxq);
1389 
1390 	/* Initialize reusable tunnel packet header */
1391 	tipc_msg_init(tipc_own_addr(l->net), &tnlhdr, TUNNEL_PROTOCOL,
1392 		      mtyp, INT_H_SIZE, l->addr);
1393 	pktcnt = skb_queue_len(&l->transmq) + skb_queue_len(&l->backlogq);
1394 	msg_set_msgcnt(&tnlhdr, pktcnt);
1395 	msg_set_bearer_id(&tnlhdr, l->peer_bearer_id);
1396 tnl:
1397 	/* Wrap each packet into a tunnel packet */
1398 	skb_queue_walk(queue, skb) {
1399 		hdr = buf_msg(skb);
1400 		if (queue == &l->backlogq)
1401 			msg_set_seqno(hdr, seqno++);
1402 		pktlen = msg_size(hdr);
1403 		msg_set_size(&tnlhdr, pktlen + INT_H_SIZE);
1404 		tnlskb = tipc_buf_acquire(pktlen + INT_H_SIZE, GFP_ATOMIC);
1405 		if (!tnlskb) {
1406 			pr_warn("%sunable to send packet\n", link_co_err);
1407 			return;
1408 		}
1409 		skb_copy_to_linear_data(tnlskb, &tnlhdr, INT_H_SIZE);
1410 		skb_copy_to_linear_data_offset(tnlskb, INT_H_SIZE, hdr, pktlen);
1411 		__skb_queue_tail(&tnlq, tnlskb);
1412 	}
1413 	if (queue != &l->backlogq) {
1414 		queue = &l->backlogq;
1415 		goto tnl;
1416 	}
1417 
1418 	tipc_link_xmit(tnl, &tnlq, xmitq);
1419 
1420 	if (mtyp == FAILOVER_MSG) {
1421 		tnl->drop_point = l->rcv_nxt;
1422 		tnl->failover_reasm_skb = l->reasm_buf;
1423 		l->reasm_buf = NULL;
1424 	}
1425 }
1426 
1427 /* tipc_link_proto_rcv(): receive link level protocol message :
1428  * Note that network plane id propagates through the network, and may
1429  * change at any time. The node with lowest numerical id determines
1430  * network plane
1431  */
1432 static int tipc_link_proto_rcv(struct tipc_link *l, struct sk_buff *skb,
1433 			       struct sk_buff_head *xmitq)
1434 {
1435 	struct tipc_msg *hdr = buf_msg(skb);
1436 	u16 rcvgap = 0;
1437 	u16 ack = msg_ack(hdr);
1438 	u16 gap = msg_seq_gap(hdr);
1439 	u16 peers_snd_nxt =  msg_next_sent(hdr);
1440 	u16 peers_tol = msg_link_tolerance(hdr);
1441 	u16 peers_prio = msg_linkprio(hdr);
1442 	u16 rcv_nxt = l->rcv_nxt;
1443 	u16 dlen = msg_data_sz(hdr);
1444 	int mtyp = msg_type(hdr);
1445 	void *data;
1446 	char *if_name;
1447 	int rc = 0;
1448 
1449 	if (tipc_link_is_blocked(l) || !xmitq)
1450 		goto exit;
1451 
1452 	if (tipc_own_addr(l->net) > msg_prevnode(hdr))
1453 		l->net_plane = msg_net_plane(hdr);
1454 
1455 	skb_linearize(skb);
1456 	hdr = buf_msg(skb);
1457 	data = msg_data(hdr);
1458 
1459 	switch (mtyp) {
1460 	case RESET_MSG:
1461 
1462 		/* Ignore duplicate RESET with old session number */
1463 		if ((less_eq(msg_session(hdr), l->peer_session)) &&
1464 		    (l->peer_session != ANY_SESSION))
1465 			break;
1466 		/* fall thru' */
1467 
1468 	case ACTIVATE_MSG:
1469 
1470 		/* Complete own link name with peer's interface name */
1471 		if_name =  strrchr(l->name, ':') + 1;
1472 		if (sizeof(l->name) - (if_name - l->name) <= TIPC_MAX_IF_NAME)
1473 			break;
1474 		if (msg_data_sz(hdr) < TIPC_MAX_IF_NAME)
1475 			break;
1476 		strncpy(if_name, data, TIPC_MAX_IF_NAME);
1477 
1478 		/* Update own tolerance if peer indicates a non-zero value */
1479 		if (in_range(peers_tol, TIPC_MIN_LINK_TOL, TIPC_MAX_LINK_TOL))
1480 			l->tolerance = peers_tol;
1481 
1482 		/* Update own priority if peer's priority is higher */
1483 		if (in_range(peers_prio, l->priority + 1, TIPC_MAX_LINK_PRI))
1484 			l->priority = peers_prio;
1485 
1486 		/* ACTIVATE_MSG serves as PEER_RESET if link is already down */
1487 		if (msg_peer_stopping(hdr))
1488 			rc = tipc_link_fsm_evt(l, LINK_FAILURE_EVT);
1489 		else if ((mtyp == RESET_MSG) || !link_is_up(l))
1490 			rc = tipc_link_fsm_evt(l, LINK_PEER_RESET_EVT);
1491 
1492 		/* ACTIVATE_MSG takes up link if it was already locally reset */
1493 		if ((mtyp == ACTIVATE_MSG) && (l->state == LINK_ESTABLISHING))
1494 			rc = TIPC_LINK_UP_EVT;
1495 
1496 		l->peer_session = msg_session(hdr);
1497 		l->peer_bearer_id = msg_bearer_id(hdr);
1498 		if (l->mtu > msg_max_pkt(hdr))
1499 			l->mtu = msg_max_pkt(hdr);
1500 		break;
1501 
1502 	case STATE_MSG:
1503 
1504 		/* Update own tolerance if peer indicates a non-zero value */
1505 		if (in_range(peers_tol, TIPC_MIN_LINK_TOL, TIPC_MAX_LINK_TOL))
1506 			l->tolerance = peers_tol;
1507 
1508 		/* Update own prio if peer indicates a different value */
1509 		if ((peers_prio != l->priority) &&
1510 		    in_range(peers_prio, 1, TIPC_MAX_LINK_PRI)) {
1511 			l->priority = peers_prio;
1512 			rc = tipc_link_fsm_evt(l, LINK_FAILURE_EVT);
1513 		}
1514 
1515 		l->silent_intv_cnt = 0;
1516 		l->stats.recv_states++;
1517 		if (msg_probe(hdr))
1518 			l->stats.recv_probes++;
1519 
1520 		if (!link_is_up(l)) {
1521 			if (l->state == LINK_ESTABLISHING)
1522 				rc = TIPC_LINK_UP_EVT;
1523 			break;
1524 		}
1525 		tipc_mon_rcv(l->net, data, dlen, l->addr,
1526 			     &l->mon_state, l->bearer_id);
1527 
1528 		/* Send NACK if peer has sent pkts we haven't received yet */
1529 		if (more(peers_snd_nxt, rcv_nxt) && !tipc_link_is_synching(l))
1530 			rcvgap = peers_snd_nxt - l->rcv_nxt;
1531 		if (rcvgap || (msg_probe(hdr)))
1532 			tipc_link_build_proto_msg(l, STATE_MSG, 0, rcvgap,
1533 						  0, 0, xmitq);
1534 		tipc_link_release_pkts(l, ack);
1535 
1536 		/* If NACK, retransmit will now start at right position */
1537 		if (gap) {
1538 			rc = tipc_link_retrans(l, l, ack + 1, ack + gap, xmitq);
1539 			l->stats.recv_nacks++;
1540 		}
1541 
1542 		tipc_link_advance_backlog(l, xmitq);
1543 		if (unlikely(!skb_queue_empty(&l->wakeupq)))
1544 			link_prepare_wakeup(l);
1545 	}
1546 exit:
1547 	kfree_skb(skb);
1548 	return rc;
1549 }
1550 
1551 /* tipc_link_build_bc_proto_msg() - create broadcast protocol message
1552  */
1553 static bool tipc_link_build_bc_proto_msg(struct tipc_link *l, bool bcast,
1554 					 u16 peers_snd_nxt,
1555 					 struct sk_buff_head *xmitq)
1556 {
1557 	struct sk_buff *skb;
1558 	struct tipc_msg *hdr;
1559 	struct sk_buff *dfrd_skb = skb_peek(&l->deferdq);
1560 	u16 ack = l->rcv_nxt - 1;
1561 	u16 gap_to = peers_snd_nxt - 1;
1562 
1563 	skb = tipc_msg_create(BCAST_PROTOCOL, STATE_MSG, INT_H_SIZE,
1564 			      0, l->addr, tipc_own_addr(l->net), 0, 0, 0);
1565 	if (!skb)
1566 		return false;
1567 	hdr = buf_msg(skb);
1568 	msg_set_last_bcast(hdr, l->bc_sndlink->snd_nxt - 1);
1569 	msg_set_bcast_ack(hdr, ack);
1570 	msg_set_bcgap_after(hdr, ack);
1571 	if (dfrd_skb)
1572 		gap_to = buf_seqno(dfrd_skb) - 1;
1573 	msg_set_bcgap_to(hdr, gap_to);
1574 	msg_set_non_seq(hdr, bcast);
1575 	__skb_queue_tail(xmitq, skb);
1576 	return true;
1577 }
1578 
1579 /* tipc_link_build_bc_init_msg() - synchronize broadcast link endpoints.
1580  *
1581  * Give a newly added peer node the sequence number where it should
1582  * start receiving and acking broadcast packets.
1583  */
1584 static void tipc_link_build_bc_init_msg(struct tipc_link *l,
1585 					struct sk_buff_head *xmitq)
1586 {
1587 	struct sk_buff_head list;
1588 
1589 	__skb_queue_head_init(&list);
1590 	if (!tipc_link_build_bc_proto_msg(l->bc_rcvlink, false, 0, &list))
1591 		return;
1592 	msg_set_bc_ack_invalid(buf_msg(skb_peek(&list)), true);
1593 	tipc_link_xmit(l, &list, xmitq);
1594 }
1595 
1596 /* tipc_link_bc_init_rcv - receive initial broadcast synch data from peer
1597  */
1598 void tipc_link_bc_init_rcv(struct tipc_link *l, struct tipc_msg *hdr)
1599 {
1600 	int mtyp = msg_type(hdr);
1601 	u16 peers_snd_nxt = msg_bc_snd_nxt(hdr);
1602 
1603 	if (link_is_up(l))
1604 		return;
1605 
1606 	if (msg_user(hdr) == BCAST_PROTOCOL) {
1607 		l->rcv_nxt = peers_snd_nxt;
1608 		l->state = LINK_ESTABLISHED;
1609 		return;
1610 	}
1611 
1612 	if (l->peer_caps & TIPC_BCAST_SYNCH)
1613 		return;
1614 
1615 	if (msg_peer_node_is_up(hdr))
1616 		return;
1617 
1618 	/* Compatibility: accept older, less safe initial synch data */
1619 	if ((mtyp == RESET_MSG) || (mtyp == ACTIVATE_MSG))
1620 		l->rcv_nxt = peers_snd_nxt;
1621 }
1622 
1623 /* link_bc_retr eval()- check if the indicated range can be retransmitted now
1624  * - Adjust permitted range if there is overlap with previous retransmission
1625  */
1626 static bool link_bc_retr_eval(struct tipc_link *l, u16 *from, u16 *to)
1627 {
1628 	unsigned long elapsed = jiffies_to_msecs(jiffies - l->prev_retr);
1629 
1630 	if (less(*to, *from))
1631 		return false;
1632 
1633 	/* New retransmission request */
1634 	if ((elapsed > TIPC_BC_RETR_LIMIT) ||
1635 	    less(*to, l->prev_from) || more(*from, l->prev_to)) {
1636 		l->prev_from = *from;
1637 		l->prev_to = *to;
1638 		l->prev_retr = jiffies;
1639 		return true;
1640 	}
1641 
1642 	/* Inside range of previous retransmit */
1643 	if (!less(*from, l->prev_from) && !more(*to, l->prev_to))
1644 		return false;
1645 
1646 	/* Fully or partially outside previous range => exclude overlap */
1647 	if (less(*from, l->prev_from)) {
1648 		*to = l->prev_from - 1;
1649 		l->prev_from = *from;
1650 	}
1651 	if (more(*to, l->prev_to)) {
1652 		*from = l->prev_to + 1;
1653 		l->prev_to = *to;
1654 	}
1655 	l->prev_retr = jiffies;
1656 	return true;
1657 }
1658 
1659 /* tipc_link_bc_sync_rcv - update rcv link according to peer's send state
1660  */
1661 int tipc_link_bc_sync_rcv(struct tipc_link *l, struct tipc_msg *hdr,
1662 			  struct sk_buff_head *xmitq)
1663 {
1664 	struct tipc_link *snd_l = l->bc_sndlink;
1665 	u16 peers_snd_nxt = msg_bc_snd_nxt(hdr);
1666 	u16 from = msg_bcast_ack(hdr) + 1;
1667 	u16 to = from + msg_bc_gap(hdr) - 1;
1668 	int rc = 0;
1669 
1670 	if (!link_is_up(l))
1671 		return rc;
1672 
1673 	if (!msg_peer_node_is_up(hdr))
1674 		return rc;
1675 
1676 	/* Open when peer ackowledges our bcast init msg (pkt #1) */
1677 	if (msg_ack(hdr))
1678 		l->bc_peer_is_up = true;
1679 
1680 	if (!l->bc_peer_is_up)
1681 		return rc;
1682 
1683 	l->stats.recv_nacks++;
1684 
1685 	/* Ignore if peers_snd_nxt goes beyond receive window */
1686 	if (more(peers_snd_nxt, l->rcv_nxt + l->window))
1687 		return rc;
1688 
1689 	if (link_bc_retr_eval(snd_l, &from, &to))
1690 		rc = tipc_link_retrans(snd_l, l, from, to, xmitq);
1691 
1692 	l->snd_nxt = peers_snd_nxt;
1693 	if (link_bc_rcv_gap(l))
1694 		rc |= TIPC_LINK_SND_STATE;
1695 
1696 	/* Return now if sender supports nack via STATE messages */
1697 	if (l->peer_caps & TIPC_BCAST_STATE_NACK)
1698 		return rc;
1699 
1700 	/* Otherwise, be backwards compatible */
1701 
1702 	if (!more(peers_snd_nxt, l->rcv_nxt)) {
1703 		l->nack_state = BC_NACK_SND_CONDITIONAL;
1704 		return 0;
1705 	}
1706 
1707 	/* Don't NACK if one was recently sent or peeked */
1708 	if (l->nack_state == BC_NACK_SND_SUPPRESS) {
1709 		l->nack_state = BC_NACK_SND_UNCONDITIONAL;
1710 		return 0;
1711 	}
1712 
1713 	/* Conditionally delay NACK sending until next synch rcv */
1714 	if (l->nack_state == BC_NACK_SND_CONDITIONAL) {
1715 		l->nack_state = BC_NACK_SND_UNCONDITIONAL;
1716 		if ((peers_snd_nxt - l->rcv_nxt) < TIPC_MIN_LINK_WIN)
1717 			return 0;
1718 	}
1719 
1720 	/* Send NACK now but suppress next one */
1721 	tipc_link_build_bc_proto_msg(l, true, peers_snd_nxt, xmitq);
1722 	l->nack_state = BC_NACK_SND_SUPPRESS;
1723 	return 0;
1724 }
1725 
1726 void tipc_link_bc_ack_rcv(struct tipc_link *l, u16 acked,
1727 			  struct sk_buff_head *xmitq)
1728 {
1729 	struct sk_buff *skb, *tmp;
1730 	struct tipc_link *snd_l = l->bc_sndlink;
1731 
1732 	if (!link_is_up(l) || !l->bc_peer_is_up)
1733 		return;
1734 
1735 	if (!more(acked, l->acked))
1736 		return;
1737 
1738 	/* Skip over packets peer has already acked */
1739 	skb_queue_walk(&snd_l->transmq, skb) {
1740 		if (more(buf_seqno(skb), l->acked))
1741 			break;
1742 	}
1743 
1744 	/* Update/release the packets peer is acking now */
1745 	skb_queue_walk_from_safe(&snd_l->transmq, skb, tmp) {
1746 		if (more(buf_seqno(skb), acked))
1747 			break;
1748 		if (!--TIPC_SKB_CB(skb)->ackers) {
1749 			__skb_unlink(skb, &snd_l->transmq);
1750 			kfree_skb(skb);
1751 		}
1752 	}
1753 	l->acked = acked;
1754 	tipc_link_advance_backlog(snd_l, xmitq);
1755 	if (unlikely(!skb_queue_empty(&snd_l->wakeupq)))
1756 		link_prepare_wakeup(snd_l);
1757 }
1758 
1759 /* tipc_link_bc_nack_rcv(): receive broadcast nack message
1760  * This function is here for backwards compatibility, since
1761  * no BCAST_PROTOCOL/STATE messages occur from TIPC v2.5.
1762  */
1763 int tipc_link_bc_nack_rcv(struct tipc_link *l, struct sk_buff *skb,
1764 			  struct sk_buff_head *xmitq)
1765 {
1766 	struct tipc_msg *hdr = buf_msg(skb);
1767 	u32 dnode = msg_destnode(hdr);
1768 	int mtyp = msg_type(hdr);
1769 	u16 acked = msg_bcast_ack(hdr);
1770 	u16 from = acked + 1;
1771 	u16 to = msg_bcgap_to(hdr);
1772 	u16 peers_snd_nxt = to + 1;
1773 	int rc = 0;
1774 
1775 	kfree_skb(skb);
1776 
1777 	if (!tipc_link_is_up(l) || !l->bc_peer_is_up)
1778 		return 0;
1779 
1780 	if (mtyp != STATE_MSG)
1781 		return 0;
1782 
1783 	if (dnode == tipc_own_addr(l->net)) {
1784 		tipc_link_bc_ack_rcv(l, acked, xmitq);
1785 		rc = tipc_link_retrans(l->bc_sndlink, l, from, to, xmitq);
1786 		l->stats.recv_nacks++;
1787 		return rc;
1788 	}
1789 
1790 	/* Msg for other node => suppress own NACK at next sync if applicable */
1791 	if (more(peers_snd_nxt, l->rcv_nxt) && !less(l->rcv_nxt, from))
1792 		l->nack_state = BC_NACK_SND_SUPPRESS;
1793 
1794 	return 0;
1795 }
1796 
1797 void tipc_link_set_queue_limits(struct tipc_link *l, u32 win)
1798 {
1799 	int max_bulk = TIPC_MAX_PUBLICATIONS / (l->mtu / ITEM_SIZE);
1800 
1801 	l->window = win;
1802 	l->backlog[TIPC_LOW_IMPORTANCE].limit      = max_t(u16, 50, win);
1803 	l->backlog[TIPC_MEDIUM_IMPORTANCE].limit   = max_t(u16, 100, win * 2);
1804 	l->backlog[TIPC_HIGH_IMPORTANCE].limit     = max_t(u16, 150, win * 3);
1805 	l->backlog[TIPC_CRITICAL_IMPORTANCE].limit = max_t(u16, 200, win * 4);
1806 	l->backlog[TIPC_SYSTEM_IMPORTANCE].limit   = max_bulk;
1807 }
1808 
1809 /**
1810  * link_reset_stats - reset link statistics
1811  * @l: pointer to link
1812  */
1813 void tipc_link_reset_stats(struct tipc_link *l)
1814 {
1815 	memset(&l->stats, 0, sizeof(l->stats));
1816 }
1817 
1818 static void link_print(struct tipc_link *l, const char *str)
1819 {
1820 	struct sk_buff *hskb = skb_peek(&l->transmq);
1821 	u16 head = hskb ? msg_seqno(buf_msg(hskb)) : l->snd_nxt - 1;
1822 	u16 tail = l->snd_nxt - 1;
1823 
1824 	pr_info("%s Link <%s> state %x\n", str, l->name, l->state);
1825 	pr_info("XMTQ: %u [%u-%u], BKLGQ: %u, SNDNX: %u, RCVNX: %u\n",
1826 		skb_queue_len(&l->transmq), head, tail,
1827 		skb_queue_len(&l->backlogq), l->snd_nxt, l->rcv_nxt);
1828 }
1829 
1830 /* Parse and validate nested (link) properties valid for media, bearer and link
1831  */
1832 int tipc_nl_parse_link_prop(struct nlattr *prop, struct nlattr *props[])
1833 {
1834 	int err;
1835 
1836 	err = nla_parse_nested(props, TIPC_NLA_PROP_MAX, prop,
1837 			       tipc_nl_prop_policy, NULL);
1838 	if (err)
1839 		return err;
1840 
1841 	if (props[TIPC_NLA_PROP_PRIO]) {
1842 		u32 prio;
1843 
1844 		prio = nla_get_u32(props[TIPC_NLA_PROP_PRIO]);
1845 		if (prio > TIPC_MAX_LINK_PRI)
1846 			return -EINVAL;
1847 	}
1848 
1849 	if (props[TIPC_NLA_PROP_TOL]) {
1850 		u32 tol;
1851 
1852 		tol = nla_get_u32(props[TIPC_NLA_PROP_TOL]);
1853 		if ((tol < TIPC_MIN_LINK_TOL) || (tol > TIPC_MAX_LINK_TOL))
1854 			return -EINVAL;
1855 	}
1856 
1857 	if (props[TIPC_NLA_PROP_WIN]) {
1858 		u32 win;
1859 
1860 		win = nla_get_u32(props[TIPC_NLA_PROP_WIN]);
1861 		if ((win < TIPC_MIN_LINK_WIN) || (win > TIPC_MAX_LINK_WIN))
1862 			return -EINVAL;
1863 	}
1864 
1865 	return 0;
1866 }
1867 
1868 static int __tipc_nl_add_stats(struct sk_buff *skb, struct tipc_stats *s)
1869 {
1870 	int i;
1871 	struct nlattr *stats;
1872 
1873 	struct nla_map {
1874 		u32 key;
1875 		u32 val;
1876 	};
1877 
1878 	struct nla_map map[] = {
1879 		{TIPC_NLA_STATS_RX_INFO, 0},
1880 		{TIPC_NLA_STATS_RX_FRAGMENTS, s->recv_fragments},
1881 		{TIPC_NLA_STATS_RX_FRAGMENTED, s->recv_fragmented},
1882 		{TIPC_NLA_STATS_RX_BUNDLES, s->recv_bundles},
1883 		{TIPC_NLA_STATS_RX_BUNDLED, s->recv_bundled},
1884 		{TIPC_NLA_STATS_TX_INFO, 0},
1885 		{TIPC_NLA_STATS_TX_FRAGMENTS, s->sent_fragments},
1886 		{TIPC_NLA_STATS_TX_FRAGMENTED, s->sent_fragmented},
1887 		{TIPC_NLA_STATS_TX_BUNDLES, s->sent_bundles},
1888 		{TIPC_NLA_STATS_TX_BUNDLED, s->sent_bundled},
1889 		{TIPC_NLA_STATS_MSG_PROF_TOT, (s->msg_length_counts) ?
1890 			s->msg_length_counts : 1},
1891 		{TIPC_NLA_STATS_MSG_LEN_CNT, s->msg_length_counts},
1892 		{TIPC_NLA_STATS_MSG_LEN_TOT, s->msg_lengths_total},
1893 		{TIPC_NLA_STATS_MSG_LEN_P0, s->msg_length_profile[0]},
1894 		{TIPC_NLA_STATS_MSG_LEN_P1, s->msg_length_profile[1]},
1895 		{TIPC_NLA_STATS_MSG_LEN_P2, s->msg_length_profile[2]},
1896 		{TIPC_NLA_STATS_MSG_LEN_P3, s->msg_length_profile[3]},
1897 		{TIPC_NLA_STATS_MSG_LEN_P4, s->msg_length_profile[4]},
1898 		{TIPC_NLA_STATS_MSG_LEN_P5, s->msg_length_profile[5]},
1899 		{TIPC_NLA_STATS_MSG_LEN_P6, s->msg_length_profile[6]},
1900 		{TIPC_NLA_STATS_RX_STATES, s->recv_states},
1901 		{TIPC_NLA_STATS_RX_PROBES, s->recv_probes},
1902 		{TIPC_NLA_STATS_RX_NACKS, s->recv_nacks},
1903 		{TIPC_NLA_STATS_RX_DEFERRED, s->deferred_recv},
1904 		{TIPC_NLA_STATS_TX_STATES, s->sent_states},
1905 		{TIPC_NLA_STATS_TX_PROBES, s->sent_probes},
1906 		{TIPC_NLA_STATS_TX_NACKS, s->sent_nacks},
1907 		{TIPC_NLA_STATS_TX_ACKS, s->sent_acks},
1908 		{TIPC_NLA_STATS_RETRANSMITTED, s->retransmitted},
1909 		{TIPC_NLA_STATS_DUPLICATES, s->duplicates},
1910 		{TIPC_NLA_STATS_LINK_CONGS, s->link_congs},
1911 		{TIPC_NLA_STATS_MAX_QUEUE, s->max_queue_sz},
1912 		{TIPC_NLA_STATS_AVG_QUEUE, s->queue_sz_counts ?
1913 			(s->accu_queue_sz / s->queue_sz_counts) : 0}
1914 	};
1915 
1916 	stats = nla_nest_start(skb, TIPC_NLA_LINK_STATS);
1917 	if (!stats)
1918 		return -EMSGSIZE;
1919 
1920 	for (i = 0; i <  ARRAY_SIZE(map); i++)
1921 		if (nla_put_u32(skb, map[i].key, map[i].val))
1922 			goto msg_full;
1923 
1924 	nla_nest_end(skb, stats);
1925 
1926 	return 0;
1927 msg_full:
1928 	nla_nest_cancel(skb, stats);
1929 
1930 	return -EMSGSIZE;
1931 }
1932 
1933 /* Caller should hold appropriate locks to protect the link */
1934 int __tipc_nl_add_link(struct net *net, struct tipc_nl_msg *msg,
1935 		       struct tipc_link *link, int nlflags)
1936 {
1937 	int err;
1938 	void *hdr;
1939 	struct nlattr *attrs;
1940 	struct nlattr *prop;
1941 	struct tipc_net *tn = net_generic(net, tipc_net_id);
1942 
1943 	hdr = genlmsg_put(msg->skb, msg->portid, msg->seq, &tipc_genl_family,
1944 			  nlflags, TIPC_NL_LINK_GET);
1945 	if (!hdr)
1946 		return -EMSGSIZE;
1947 
1948 	attrs = nla_nest_start(msg->skb, TIPC_NLA_LINK);
1949 	if (!attrs)
1950 		goto msg_full;
1951 
1952 	if (nla_put_string(msg->skb, TIPC_NLA_LINK_NAME, link->name))
1953 		goto attr_msg_full;
1954 	if (nla_put_u32(msg->skb, TIPC_NLA_LINK_DEST,
1955 			tipc_cluster_mask(tn->own_addr)))
1956 		goto attr_msg_full;
1957 	if (nla_put_u32(msg->skb, TIPC_NLA_LINK_MTU, link->mtu))
1958 		goto attr_msg_full;
1959 	if (nla_put_u32(msg->skb, TIPC_NLA_LINK_RX, link->stats.recv_pkts))
1960 		goto attr_msg_full;
1961 	if (nla_put_u32(msg->skb, TIPC_NLA_LINK_TX, link->stats.sent_pkts))
1962 		goto attr_msg_full;
1963 
1964 	if (tipc_link_is_up(link))
1965 		if (nla_put_flag(msg->skb, TIPC_NLA_LINK_UP))
1966 			goto attr_msg_full;
1967 	if (link->active)
1968 		if (nla_put_flag(msg->skb, TIPC_NLA_LINK_ACTIVE))
1969 			goto attr_msg_full;
1970 
1971 	prop = nla_nest_start(msg->skb, TIPC_NLA_LINK_PROP);
1972 	if (!prop)
1973 		goto attr_msg_full;
1974 	if (nla_put_u32(msg->skb, TIPC_NLA_PROP_PRIO, link->priority))
1975 		goto prop_msg_full;
1976 	if (nla_put_u32(msg->skb, TIPC_NLA_PROP_TOL, link->tolerance))
1977 		goto prop_msg_full;
1978 	if (nla_put_u32(msg->skb, TIPC_NLA_PROP_WIN,
1979 			link->window))
1980 		goto prop_msg_full;
1981 	if (nla_put_u32(msg->skb, TIPC_NLA_PROP_PRIO, link->priority))
1982 		goto prop_msg_full;
1983 	nla_nest_end(msg->skb, prop);
1984 
1985 	err = __tipc_nl_add_stats(msg->skb, &link->stats);
1986 	if (err)
1987 		goto attr_msg_full;
1988 
1989 	nla_nest_end(msg->skb, attrs);
1990 	genlmsg_end(msg->skb, hdr);
1991 
1992 	return 0;
1993 
1994 prop_msg_full:
1995 	nla_nest_cancel(msg->skb, prop);
1996 attr_msg_full:
1997 	nla_nest_cancel(msg->skb, attrs);
1998 msg_full:
1999 	genlmsg_cancel(msg->skb, hdr);
2000 
2001 	return -EMSGSIZE;
2002 }
2003 
2004 static int __tipc_nl_add_bc_link_stat(struct sk_buff *skb,
2005 				      struct tipc_stats *stats)
2006 {
2007 	int i;
2008 	struct nlattr *nest;
2009 
2010 	struct nla_map {
2011 		__u32 key;
2012 		__u32 val;
2013 	};
2014 
2015 	struct nla_map map[] = {
2016 		{TIPC_NLA_STATS_RX_INFO, stats->recv_pkts},
2017 		{TIPC_NLA_STATS_RX_FRAGMENTS, stats->recv_fragments},
2018 		{TIPC_NLA_STATS_RX_FRAGMENTED, stats->recv_fragmented},
2019 		{TIPC_NLA_STATS_RX_BUNDLES, stats->recv_bundles},
2020 		{TIPC_NLA_STATS_RX_BUNDLED, stats->recv_bundled},
2021 		{TIPC_NLA_STATS_TX_INFO, stats->sent_pkts},
2022 		{TIPC_NLA_STATS_TX_FRAGMENTS, stats->sent_fragments},
2023 		{TIPC_NLA_STATS_TX_FRAGMENTED, stats->sent_fragmented},
2024 		{TIPC_NLA_STATS_TX_BUNDLES, stats->sent_bundles},
2025 		{TIPC_NLA_STATS_TX_BUNDLED, stats->sent_bundled},
2026 		{TIPC_NLA_STATS_RX_NACKS, stats->recv_nacks},
2027 		{TIPC_NLA_STATS_RX_DEFERRED, stats->deferred_recv},
2028 		{TIPC_NLA_STATS_TX_NACKS, stats->sent_nacks},
2029 		{TIPC_NLA_STATS_TX_ACKS, stats->sent_acks},
2030 		{TIPC_NLA_STATS_RETRANSMITTED, stats->retransmitted},
2031 		{TIPC_NLA_STATS_DUPLICATES, stats->duplicates},
2032 		{TIPC_NLA_STATS_LINK_CONGS, stats->link_congs},
2033 		{TIPC_NLA_STATS_MAX_QUEUE, stats->max_queue_sz},
2034 		{TIPC_NLA_STATS_AVG_QUEUE, stats->queue_sz_counts ?
2035 			(stats->accu_queue_sz / stats->queue_sz_counts) : 0}
2036 	};
2037 
2038 	nest = nla_nest_start(skb, TIPC_NLA_LINK_STATS);
2039 	if (!nest)
2040 		return -EMSGSIZE;
2041 
2042 	for (i = 0; i <  ARRAY_SIZE(map); i++)
2043 		if (nla_put_u32(skb, map[i].key, map[i].val))
2044 			goto msg_full;
2045 
2046 	nla_nest_end(skb, nest);
2047 
2048 	return 0;
2049 msg_full:
2050 	nla_nest_cancel(skb, nest);
2051 
2052 	return -EMSGSIZE;
2053 }
2054 
2055 int tipc_nl_add_bc_link(struct net *net, struct tipc_nl_msg *msg)
2056 {
2057 	int err;
2058 	void *hdr;
2059 	struct nlattr *attrs;
2060 	struct nlattr *prop;
2061 	struct tipc_net *tn = net_generic(net, tipc_net_id);
2062 	struct tipc_link *bcl = tn->bcl;
2063 
2064 	if (!bcl)
2065 		return 0;
2066 
2067 	tipc_bcast_lock(net);
2068 
2069 	hdr = genlmsg_put(msg->skb, msg->portid, msg->seq, &tipc_genl_family,
2070 			  NLM_F_MULTI, TIPC_NL_LINK_GET);
2071 	if (!hdr) {
2072 		tipc_bcast_unlock(net);
2073 		return -EMSGSIZE;
2074 	}
2075 
2076 	attrs = nla_nest_start(msg->skb, TIPC_NLA_LINK);
2077 	if (!attrs)
2078 		goto msg_full;
2079 
2080 	/* The broadcast link is always up */
2081 	if (nla_put_flag(msg->skb, TIPC_NLA_LINK_UP))
2082 		goto attr_msg_full;
2083 
2084 	if (nla_put_flag(msg->skb, TIPC_NLA_LINK_BROADCAST))
2085 		goto attr_msg_full;
2086 	if (nla_put_string(msg->skb, TIPC_NLA_LINK_NAME, bcl->name))
2087 		goto attr_msg_full;
2088 	if (nla_put_u32(msg->skb, TIPC_NLA_LINK_RX, 0))
2089 		goto attr_msg_full;
2090 	if (nla_put_u32(msg->skb, TIPC_NLA_LINK_TX, 0))
2091 		goto attr_msg_full;
2092 
2093 	prop = nla_nest_start(msg->skb, TIPC_NLA_LINK_PROP);
2094 	if (!prop)
2095 		goto attr_msg_full;
2096 	if (nla_put_u32(msg->skb, TIPC_NLA_PROP_WIN, bcl->window))
2097 		goto prop_msg_full;
2098 	nla_nest_end(msg->skb, prop);
2099 
2100 	err = __tipc_nl_add_bc_link_stat(msg->skb, &bcl->stats);
2101 	if (err)
2102 		goto attr_msg_full;
2103 
2104 	tipc_bcast_unlock(net);
2105 	nla_nest_end(msg->skb, attrs);
2106 	genlmsg_end(msg->skb, hdr);
2107 
2108 	return 0;
2109 
2110 prop_msg_full:
2111 	nla_nest_cancel(msg->skb, prop);
2112 attr_msg_full:
2113 	nla_nest_cancel(msg->skb, attrs);
2114 msg_full:
2115 	tipc_bcast_unlock(net);
2116 	genlmsg_cancel(msg->skb, hdr);
2117 
2118 	return -EMSGSIZE;
2119 }
2120 
2121 void tipc_link_set_tolerance(struct tipc_link *l, u32 tol,
2122 			     struct sk_buff_head *xmitq)
2123 {
2124 	l->tolerance = tol;
2125 	tipc_link_build_proto_msg(l, STATE_MSG, 0, 0, tol, 0, xmitq);
2126 }
2127 
2128 void tipc_link_set_prio(struct tipc_link *l, u32 prio,
2129 			struct sk_buff_head *xmitq)
2130 {
2131 	l->priority = prio;
2132 	tipc_link_build_proto_msg(l, STATE_MSG, 0, 0, 0, prio, xmitq);
2133 }
2134 
2135 void tipc_link_set_abort_limit(struct tipc_link *l, u32 limit)
2136 {
2137 	l->abort_limit = limit;
2138 }
2139