xref: /openbmc/linux/net/tipc/link.c (revision fc28ab18)
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 	return true;
519 }
520 
521 /**
522  * tipc_link_fsm_evt - link finite state machine
523  * @l: pointer to link
524  * @evt: state machine event to be processed
525  */
526 int tipc_link_fsm_evt(struct tipc_link *l, int evt)
527 {
528 	int rc = 0;
529 
530 	switch (l->state) {
531 	case LINK_RESETTING:
532 		switch (evt) {
533 		case LINK_PEER_RESET_EVT:
534 			l->state = LINK_PEER_RESET;
535 			break;
536 		case LINK_RESET_EVT:
537 			l->state = LINK_RESET;
538 			break;
539 		case LINK_FAILURE_EVT:
540 		case LINK_FAILOVER_BEGIN_EVT:
541 		case LINK_ESTABLISH_EVT:
542 		case LINK_FAILOVER_END_EVT:
543 		case LINK_SYNCH_BEGIN_EVT:
544 		case LINK_SYNCH_END_EVT:
545 		default:
546 			goto illegal_evt;
547 		}
548 		break;
549 	case LINK_RESET:
550 		switch (evt) {
551 		case LINK_PEER_RESET_EVT:
552 			l->state = LINK_ESTABLISHING;
553 			break;
554 		case LINK_FAILOVER_BEGIN_EVT:
555 			l->state = LINK_FAILINGOVER;
556 		case LINK_FAILURE_EVT:
557 		case LINK_RESET_EVT:
558 		case LINK_ESTABLISH_EVT:
559 		case LINK_FAILOVER_END_EVT:
560 			break;
561 		case LINK_SYNCH_BEGIN_EVT:
562 		case LINK_SYNCH_END_EVT:
563 		default:
564 			goto illegal_evt;
565 		}
566 		break;
567 	case LINK_PEER_RESET:
568 		switch (evt) {
569 		case LINK_RESET_EVT:
570 			l->state = LINK_ESTABLISHING;
571 			break;
572 		case LINK_PEER_RESET_EVT:
573 		case LINK_ESTABLISH_EVT:
574 		case LINK_FAILURE_EVT:
575 			break;
576 		case LINK_SYNCH_BEGIN_EVT:
577 		case LINK_SYNCH_END_EVT:
578 		case LINK_FAILOVER_BEGIN_EVT:
579 		case LINK_FAILOVER_END_EVT:
580 		default:
581 			goto illegal_evt;
582 		}
583 		break;
584 	case LINK_FAILINGOVER:
585 		switch (evt) {
586 		case LINK_FAILOVER_END_EVT:
587 			l->state = LINK_RESET;
588 			break;
589 		case LINK_PEER_RESET_EVT:
590 		case LINK_RESET_EVT:
591 		case LINK_ESTABLISH_EVT:
592 		case LINK_FAILURE_EVT:
593 			break;
594 		case LINK_FAILOVER_BEGIN_EVT:
595 		case LINK_SYNCH_BEGIN_EVT:
596 		case LINK_SYNCH_END_EVT:
597 		default:
598 			goto illegal_evt;
599 		}
600 		break;
601 	case LINK_ESTABLISHING:
602 		switch (evt) {
603 		case LINK_ESTABLISH_EVT:
604 			l->state = LINK_ESTABLISHED;
605 			break;
606 		case LINK_FAILOVER_BEGIN_EVT:
607 			l->state = LINK_FAILINGOVER;
608 			break;
609 		case LINK_RESET_EVT:
610 			l->state = LINK_RESET;
611 			break;
612 		case LINK_FAILURE_EVT:
613 		case LINK_PEER_RESET_EVT:
614 		case LINK_SYNCH_BEGIN_EVT:
615 		case LINK_FAILOVER_END_EVT:
616 			break;
617 		case LINK_SYNCH_END_EVT:
618 		default:
619 			goto illegal_evt;
620 		}
621 		break;
622 	case LINK_ESTABLISHED:
623 		switch (evt) {
624 		case LINK_PEER_RESET_EVT:
625 			l->state = LINK_PEER_RESET;
626 			rc |= TIPC_LINK_DOWN_EVT;
627 			break;
628 		case LINK_FAILURE_EVT:
629 			l->state = LINK_RESETTING;
630 			rc |= TIPC_LINK_DOWN_EVT;
631 			break;
632 		case LINK_RESET_EVT:
633 			l->state = LINK_RESET;
634 			break;
635 		case LINK_ESTABLISH_EVT:
636 		case LINK_SYNCH_END_EVT:
637 			break;
638 		case LINK_SYNCH_BEGIN_EVT:
639 			l->state = LINK_SYNCHING;
640 			break;
641 		case LINK_FAILOVER_BEGIN_EVT:
642 		case LINK_FAILOVER_END_EVT:
643 		default:
644 			goto illegal_evt;
645 		}
646 		break;
647 	case LINK_SYNCHING:
648 		switch (evt) {
649 		case LINK_PEER_RESET_EVT:
650 			l->state = LINK_PEER_RESET;
651 			rc |= TIPC_LINK_DOWN_EVT;
652 			break;
653 		case LINK_FAILURE_EVT:
654 			l->state = LINK_RESETTING;
655 			rc |= TIPC_LINK_DOWN_EVT;
656 			break;
657 		case LINK_RESET_EVT:
658 			l->state = LINK_RESET;
659 			break;
660 		case LINK_ESTABLISH_EVT:
661 		case LINK_SYNCH_BEGIN_EVT:
662 			break;
663 		case LINK_SYNCH_END_EVT:
664 			l->state = LINK_ESTABLISHED;
665 			break;
666 		case LINK_FAILOVER_BEGIN_EVT:
667 		case LINK_FAILOVER_END_EVT:
668 		default:
669 			goto illegal_evt;
670 		}
671 		break;
672 	default:
673 		pr_err("Unknown FSM state %x in %s\n", l->state, l->name);
674 	}
675 	return rc;
676 illegal_evt:
677 	pr_err("Illegal FSM event %x in state %x on link %s\n",
678 	       evt, l->state, l->name);
679 	return rc;
680 }
681 
682 /* link_profile_stats - update statistical profiling of traffic
683  */
684 static void link_profile_stats(struct tipc_link *l)
685 {
686 	struct sk_buff *skb;
687 	struct tipc_msg *msg;
688 	int length;
689 
690 	/* Update counters used in statistical profiling of send traffic */
691 	l->stats.accu_queue_sz += skb_queue_len(&l->transmq);
692 	l->stats.queue_sz_counts++;
693 
694 	skb = skb_peek(&l->transmq);
695 	if (!skb)
696 		return;
697 	msg = buf_msg(skb);
698 	length = msg_size(msg);
699 
700 	if (msg_user(msg) == MSG_FRAGMENTER) {
701 		if (msg_type(msg) != FIRST_FRAGMENT)
702 			return;
703 		length = msg_size(msg_get_wrapped(msg));
704 	}
705 	l->stats.msg_lengths_total += length;
706 	l->stats.msg_length_counts++;
707 	if (length <= 64)
708 		l->stats.msg_length_profile[0]++;
709 	else if (length <= 256)
710 		l->stats.msg_length_profile[1]++;
711 	else if (length <= 1024)
712 		l->stats.msg_length_profile[2]++;
713 	else if (length <= 4096)
714 		l->stats.msg_length_profile[3]++;
715 	else if (length <= 16384)
716 		l->stats.msg_length_profile[4]++;
717 	else if (length <= 32768)
718 		l->stats.msg_length_profile[5]++;
719 	else
720 		l->stats.msg_length_profile[6]++;
721 }
722 
723 /* tipc_link_timeout - perform periodic task as instructed from node timeout
724  */
725 int tipc_link_timeout(struct tipc_link *l, struct sk_buff_head *xmitq)
726 {
727 	int mtyp = 0;
728 	int rc = 0;
729 	bool state = false;
730 	bool probe = false;
731 	bool setup = false;
732 	u16 bc_snt = l->bc_sndlink->snd_nxt - 1;
733 	u16 bc_acked = l->bc_rcvlink->acked;
734 	struct tipc_mon_state *mstate = &l->mon_state;
735 
736 	switch (l->state) {
737 	case LINK_ESTABLISHED:
738 	case LINK_SYNCHING:
739 		mtyp = STATE_MSG;
740 		link_profile_stats(l);
741 		tipc_mon_get_state(l->net, l->addr, mstate, l->bearer_id);
742 		if (mstate->reset || (l->silent_intv_cnt > l->abort_limit))
743 			return tipc_link_fsm_evt(l, LINK_FAILURE_EVT);
744 		state = bc_acked != bc_snt;
745 		state |= l->bc_rcvlink->rcv_unacked;
746 		state |= l->rcv_unacked;
747 		state |= !skb_queue_empty(&l->transmq);
748 		state |= !skb_queue_empty(&l->deferdq);
749 		probe = mstate->probing;
750 		probe |= l->silent_intv_cnt;
751 		if (probe || mstate->monitoring)
752 			l->silent_intv_cnt++;
753 		break;
754 	case LINK_RESET:
755 		setup = l->rst_cnt++ <= 4;
756 		setup |= !(l->rst_cnt % 16);
757 		mtyp = RESET_MSG;
758 		break;
759 	case LINK_ESTABLISHING:
760 		setup = true;
761 		mtyp = ACTIVATE_MSG;
762 		break;
763 	case LINK_PEER_RESET:
764 	case LINK_RESETTING:
765 	case LINK_FAILINGOVER:
766 		break;
767 	default:
768 		break;
769 	}
770 
771 	if (state || probe || setup)
772 		tipc_link_build_proto_msg(l, mtyp, probe, 0, 0, 0, xmitq);
773 
774 	return rc;
775 }
776 
777 /**
778  * link_schedule_user - schedule a message sender for wakeup after congestion
779  * @link: congested link
780  * @list: message that was attempted sent
781  * Create pseudo msg to send back to user when congestion abates
782  * Does not consume buffer list
783  */
784 static int link_schedule_user(struct tipc_link *link, struct sk_buff_head *list)
785 {
786 	struct tipc_msg *msg = buf_msg(skb_peek(list));
787 	int imp = msg_importance(msg);
788 	u32 oport = msg_origport(msg);
789 	u32 addr = tipc_own_addr(link->net);
790 	struct sk_buff *skb;
791 
792 	/* This really cannot happen...  */
793 	if (unlikely(imp > TIPC_CRITICAL_IMPORTANCE)) {
794 		pr_warn("%s<%s>, send queue full", link_rst_msg, link->name);
795 		return -ENOBUFS;
796 	}
797 	/* Non-blocking sender: */
798 	if (TIPC_SKB_CB(skb_peek(list))->wakeup_pending)
799 		return -ELINKCONG;
800 
801 	/* Create and schedule wakeup pseudo message */
802 	skb = tipc_msg_create(SOCK_WAKEUP, 0, INT_H_SIZE, 0,
803 			      addr, addr, oport, 0, 0);
804 	if (!skb)
805 		return -ENOBUFS;
806 	TIPC_SKB_CB(skb)->chain_sz = skb_queue_len(list);
807 	TIPC_SKB_CB(skb)->chain_imp = imp;
808 	skb_queue_tail(&link->wakeupq, skb);
809 	link->stats.link_congs++;
810 	return -ELINKCONG;
811 }
812 
813 /**
814  * link_prepare_wakeup - prepare users for wakeup after congestion
815  * @link: congested link
816  * Move a number of waiting users, as permitted by available space in
817  * the send queue, from link wait queue to node wait queue for wakeup
818  */
819 void link_prepare_wakeup(struct tipc_link *l)
820 {
821 	int pnd[TIPC_SYSTEM_IMPORTANCE + 1] = {0,};
822 	int imp, lim;
823 	struct sk_buff *skb, *tmp;
824 
825 	skb_queue_walk_safe(&l->wakeupq, skb, tmp) {
826 		imp = TIPC_SKB_CB(skb)->chain_imp;
827 		lim = l->backlog[imp].limit;
828 		pnd[imp] += TIPC_SKB_CB(skb)->chain_sz;
829 		if ((pnd[imp] + l->backlog[imp].len) >= lim)
830 			break;
831 		skb_unlink(skb, &l->wakeupq);
832 		skb_queue_tail(l->inputq, skb);
833 	}
834 }
835 
836 void tipc_link_reset(struct tipc_link *l)
837 {
838 	l->peer_session = ANY_SESSION;
839 	l->session++;
840 	l->mtu = l->advertised_mtu;
841 	__skb_queue_purge(&l->transmq);
842 	__skb_queue_purge(&l->deferdq);
843 	skb_queue_splice_init(&l->wakeupq, l->inputq);
844 	__skb_queue_purge(&l->backlogq);
845 	l->backlog[TIPC_LOW_IMPORTANCE].len = 0;
846 	l->backlog[TIPC_MEDIUM_IMPORTANCE].len = 0;
847 	l->backlog[TIPC_HIGH_IMPORTANCE].len = 0;
848 	l->backlog[TIPC_CRITICAL_IMPORTANCE].len = 0;
849 	l->backlog[TIPC_SYSTEM_IMPORTANCE].len = 0;
850 	kfree_skb(l->reasm_buf);
851 	kfree_skb(l->failover_reasm_skb);
852 	l->reasm_buf = NULL;
853 	l->failover_reasm_skb = NULL;
854 	l->rcv_unacked = 0;
855 	l->snd_nxt = 1;
856 	l->rcv_nxt = 1;
857 	l->acked = 0;
858 	l->silent_intv_cnt = 0;
859 	l->rst_cnt = 0;
860 	l->stale_count = 0;
861 	l->bc_peer_is_up = false;
862 	memset(&l->mon_state, 0, sizeof(l->mon_state));
863 	tipc_link_reset_stats(l);
864 }
865 
866 /**
867  * tipc_link_xmit(): enqueue buffer list according to queue situation
868  * @link: link to use
869  * @list: chain of buffers containing message
870  * @xmitq: returned list of packets to be sent by caller
871  *
872  * Consumes the buffer chain, except when returning -ELINKCONG,
873  * since the caller then may want to make more send attempts.
874  * Returns 0 if success, or errno: -ELINKCONG, -EMSGSIZE or -ENOBUFS
875  * Messages at TIPC_SYSTEM_IMPORTANCE are always accepted
876  */
877 int tipc_link_xmit(struct tipc_link *l, struct sk_buff_head *list,
878 		   struct sk_buff_head *xmitq)
879 {
880 	struct tipc_msg *hdr = buf_msg(skb_peek(list));
881 	unsigned int maxwin = l->window;
882 	unsigned int i, imp = msg_importance(hdr);
883 	unsigned int mtu = l->mtu;
884 	u16 ack = l->rcv_nxt - 1;
885 	u16 seqno = l->snd_nxt;
886 	u16 bc_ack = l->bc_rcvlink->rcv_nxt - 1;
887 	struct sk_buff_head *transmq = &l->transmq;
888 	struct sk_buff_head *backlogq = &l->backlogq;
889 	struct sk_buff *skb, *_skb, *bskb;
890 	int pkt_cnt = skb_queue_len(list);
891 
892 	/* Match msg importance against this and all higher backlog limits: */
893 	if (!skb_queue_empty(backlogq)) {
894 		for (i = imp; i <= TIPC_SYSTEM_IMPORTANCE; i++) {
895 			if (unlikely(l->backlog[i].len >= l->backlog[i].limit))
896 				return link_schedule_user(l, list);
897 		}
898 	}
899 	if (unlikely(msg_size(hdr) > mtu)) {
900 		skb_queue_purge(list);
901 		return -EMSGSIZE;
902 	}
903 
904 	if (pkt_cnt > 1) {
905 		l->stats.sent_fragmented++;
906 		l->stats.sent_fragments += pkt_cnt;
907 	}
908 
909 	/* Prepare each packet for sending, and add to relevant queue: */
910 	while (skb_queue_len(list)) {
911 		skb = skb_peek(list);
912 		hdr = buf_msg(skb);
913 		msg_set_seqno(hdr, seqno);
914 		msg_set_ack(hdr, ack);
915 		msg_set_bcast_ack(hdr, bc_ack);
916 
917 		if (likely(skb_queue_len(transmq) < maxwin)) {
918 			_skb = skb_clone(skb, GFP_ATOMIC);
919 			if (!_skb) {
920 				skb_queue_purge(list);
921 				return -ENOBUFS;
922 			}
923 			__skb_dequeue(list);
924 			__skb_queue_tail(transmq, skb);
925 			__skb_queue_tail(xmitq, _skb);
926 			TIPC_SKB_CB(skb)->ackers = l->ackers;
927 			l->rcv_unacked = 0;
928 			l->stats.sent_pkts++;
929 			seqno++;
930 			continue;
931 		}
932 		if (tipc_msg_bundle(skb_peek_tail(backlogq), hdr, mtu)) {
933 			kfree_skb(__skb_dequeue(list));
934 			l->stats.sent_bundled++;
935 			continue;
936 		}
937 		if (tipc_msg_make_bundle(&bskb, hdr, mtu, l->addr)) {
938 			kfree_skb(__skb_dequeue(list));
939 			__skb_queue_tail(backlogq, bskb);
940 			l->backlog[msg_importance(buf_msg(bskb))].len++;
941 			l->stats.sent_bundled++;
942 			l->stats.sent_bundles++;
943 			continue;
944 		}
945 		l->backlog[imp].len += skb_queue_len(list);
946 		skb_queue_splice_tail_init(list, backlogq);
947 	}
948 	l->snd_nxt = seqno;
949 	return 0;
950 }
951 
952 void tipc_link_advance_backlog(struct tipc_link *l, struct sk_buff_head *xmitq)
953 {
954 	struct sk_buff *skb, *_skb;
955 	struct tipc_msg *hdr;
956 	u16 seqno = l->snd_nxt;
957 	u16 ack = l->rcv_nxt - 1;
958 	u16 bc_ack = l->bc_rcvlink->rcv_nxt - 1;
959 
960 	while (skb_queue_len(&l->transmq) < l->window) {
961 		skb = skb_peek(&l->backlogq);
962 		if (!skb)
963 			break;
964 		_skb = skb_clone(skb, GFP_ATOMIC);
965 		if (!_skb)
966 			break;
967 		__skb_dequeue(&l->backlogq);
968 		hdr = buf_msg(skb);
969 		l->backlog[msg_importance(hdr)].len--;
970 		__skb_queue_tail(&l->transmq, skb);
971 		__skb_queue_tail(xmitq, _skb);
972 		TIPC_SKB_CB(skb)->ackers = l->ackers;
973 		msg_set_seqno(hdr, seqno);
974 		msg_set_ack(hdr, ack);
975 		msg_set_bcast_ack(hdr, bc_ack);
976 		l->rcv_unacked = 0;
977 		l->stats.sent_pkts++;
978 		seqno++;
979 	}
980 	l->snd_nxt = seqno;
981 }
982 
983 static void link_retransmit_failure(struct tipc_link *l, struct sk_buff *skb)
984 {
985 	struct tipc_msg *hdr = buf_msg(skb);
986 
987 	pr_warn("Retransmission failure on link <%s>\n", l->name);
988 	link_print(l, "Resetting link ");
989 	pr_info("Failed msg: usr %u, typ %u, len %u, err %u\n",
990 		msg_user(hdr), msg_type(hdr), msg_size(hdr), msg_errcode(hdr));
991 	pr_info("sqno %u, prev: %x, src: %x\n",
992 		msg_seqno(hdr), msg_prevnode(hdr), msg_orignode(hdr));
993 }
994 
995 int tipc_link_retrans(struct tipc_link *l, u16 from, u16 to,
996 		      struct sk_buff_head *xmitq)
997 {
998 	struct sk_buff *_skb, *skb = skb_peek(&l->transmq);
999 	struct tipc_msg *hdr;
1000 	u16 ack = l->rcv_nxt - 1;
1001 	u16 bc_ack = l->bc_rcvlink->rcv_nxt - 1;
1002 
1003 	if (!skb)
1004 		return 0;
1005 
1006 	/* Detect repeated retransmit failures on same packet */
1007 	if (likely(l->last_retransm != buf_seqno(skb))) {
1008 		l->last_retransm = buf_seqno(skb);
1009 		l->stale_count = 1;
1010 	} else if (++l->stale_count > 100) {
1011 		link_retransmit_failure(l, skb);
1012 		return tipc_link_fsm_evt(l, LINK_FAILURE_EVT);
1013 	}
1014 
1015 	/* Move forward to where retransmission should start */
1016 	skb_queue_walk(&l->transmq, skb) {
1017 		if (!less(buf_seqno(skb), from))
1018 			break;
1019 	}
1020 
1021 	skb_queue_walk_from(&l->transmq, skb) {
1022 		if (more(buf_seqno(skb), to))
1023 			break;
1024 		hdr = buf_msg(skb);
1025 		_skb = __pskb_copy(skb, MIN_H_SIZE, GFP_ATOMIC);
1026 		if (!_skb)
1027 			return 0;
1028 		hdr = buf_msg(_skb);
1029 		msg_set_ack(hdr, ack);
1030 		msg_set_bcast_ack(hdr, bc_ack);
1031 		_skb->priority = TC_PRIO_CONTROL;
1032 		__skb_queue_tail(xmitq, _skb);
1033 		l->stats.retransmitted++;
1034 	}
1035 	return 0;
1036 }
1037 
1038 /* tipc_data_input - deliver data and name distr msgs to upper layer
1039  *
1040  * Consumes buffer if message is of right type
1041  * Node lock must be held
1042  */
1043 static bool tipc_data_input(struct tipc_link *l, struct sk_buff *skb,
1044 			    struct sk_buff_head *inputq)
1045 {
1046 	switch (msg_user(buf_msg(skb))) {
1047 	case TIPC_LOW_IMPORTANCE:
1048 	case TIPC_MEDIUM_IMPORTANCE:
1049 	case TIPC_HIGH_IMPORTANCE:
1050 	case TIPC_CRITICAL_IMPORTANCE:
1051 	case CONN_MANAGER:
1052 		skb_queue_tail(inputq, skb);
1053 		return true;
1054 	case NAME_DISTRIBUTOR:
1055 		l->bc_rcvlink->state = LINK_ESTABLISHED;
1056 		skb_queue_tail(l->namedq, skb);
1057 		return true;
1058 	case MSG_BUNDLER:
1059 	case TUNNEL_PROTOCOL:
1060 	case MSG_FRAGMENTER:
1061 	case BCAST_PROTOCOL:
1062 		return false;
1063 	default:
1064 		pr_warn("Dropping received illegal msg type\n");
1065 		kfree_skb(skb);
1066 		return false;
1067 	};
1068 }
1069 
1070 /* tipc_link_input - process packet that has passed link protocol check
1071  *
1072  * Consumes buffer
1073  */
1074 static int tipc_link_input(struct tipc_link *l, struct sk_buff *skb,
1075 			   struct sk_buff_head *inputq)
1076 {
1077 	struct tipc_msg *hdr = buf_msg(skb);
1078 	struct sk_buff **reasm_skb = &l->reasm_buf;
1079 	struct sk_buff *iskb;
1080 	struct sk_buff_head tmpq;
1081 	int usr = msg_user(hdr);
1082 	int rc = 0;
1083 	int pos = 0;
1084 	int ipos = 0;
1085 
1086 	if (unlikely(usr == TUNNEL_PROTOCOL)) {
1087 		if (msg_type(hdr) == SYNCH_MSG) {
1088 			__skb_queue_purge(&l->deferdq);
1089 			goto drop;
1090 		}
1091 		if (!tipc_msg_extract(skb, &iskb, &ipos))
1092 			return rc;
1093 		kfree_skb(skb);
1094 		skb = iskb;
1095 		hdr = buf_msg(skb);
1096 		if (less(msg_seqno(hdr), l->drop_point))
1097 			goto drop;
1098 		if (tipc_data_input(l, skb, inputq))
1099 			return rc;
1100 		usr = msg_user(hdr);
1101 		reasm_skb = &l->failover_reasm_skb;
1102 	}
1103 
1104 	if (usr == MSG_BUNDLER) {
1105 		skb_queue_head_init(&tmpq);
1106 		l->stats.recv_bundles++;
1107 		l->stats.recv_bundled += msg_msgcnt(hdr);
1108 		while (tipc_msg_extract(skb, &iskb, &pos))
1109 			tipc_data_input(l, iskb, &tmpq);
1110 		tipc_skb_queue_splice_tail(&tmpq, inputq);
1111 		return 0;
1112 	} else if (usr == MSG_FRAGMENTER) {
1113 		l->stats.recv_fragments++;
1114 		if (tipc_buf_append(reasm_skb, &skb)) {
1115 			l->stats.recv_fragmented++;
1116 			tipc_data_input(l, skb, inputq);
1117 		} else if (!*reasm_skb && !link_is_bc_rcvlink(l)) {
1118 			pr_warn_ratelimited("Unable to build fragment list\n");
1119 			return tipc_link_fsm_evt(l, LINK_FAILURE_EVT);
1120 		}
1121 		return 0;
1122 	} else if (usr == BCAST_PROTOCOL) {
1123 		tipc_bcast_lock(l->net);
1124 		tipc_link_bc_init_rcv(l->bc_rcvlink, hdr);
1125 		tipc_bcast_unlock(l->net);
1126 	}
1127 drop:
1128 	kfree_skb(skb);
1129 	return 0;
1130 }
1131 
1132 static bool tipc_link_release_pkts(struct tipc_link *l, u16 acked)
1133 {
1134 	bool released = false;
1135 	struct sk_buff *skb, *tmp;
1136 
1137 	skb_queue_walk_safe(&l->transmq, skb, tmp) {
1138 		if (more(buf_seqno(skb), acked))
1139 			break;
1140 		__skb_unlink(skb, &l->transmq);
1141 		kfree_skb(skb);
1142 		released = true;
1143 	}
1144 	return released;
1145 }
1146 
1147 /* tipc_link_build_state_msg: prepare link state message for transmission
1148  *
1149  * Note that sending of broadcast ack is coordinated among nodes, to reduce
1150  * risk of ack storms towards the sender
1151  */
1152 int tipc_link_build_state_msg(struct tipc_link *l, struct sk_buff_head *xmitq)
1153 {
1154 	if (!l)
1155 		return 0;
1156 
1157 	/* Broadcast ACK must be sent via a unicast link => defer to caller */
1158 	if (link_is_bc_rcvlink(l)) {
1159 		if (((l->rcv_nxt ^ tipc_own_addr(l->net)) & 0xf) != 0xf)
1160 			return 0;
1161 		l->rcv_unacked = 0;
1162 
1163 		/* Use snd_nxt to store peer's snd_nxt in broadcast rcv link */
1164 		l->snd_nxt = l->rcv_nxt;
1165 		return TIPC_LINK_SND_STATE;
1166 	}
1167 
1168 	/* Unicast ACK */
1169 	l->rcv_unacked = 0;
1170 	l->stats.sent_acks++;
1171 	tipc_link_build_proto_msg(l, STATE_MSG, 0, 0, 0, 0, xmitq);
1172 	return 0;
1173 }
1174 
1175 /* tipc_link_build_reset_msg: prepare link RESET or ACTIVATE message
1176  */
1177 void tipc_link_build_reset_msg(struct tipc_link *l, struct sk_buff_head *xmitq)
1178 {
1179 	int mtyp = RESET_MSG;
1180 	struct sk_buff *skb;
1181 
1182 	if (l->state == LINK_ESTABLISHING)
1183 		mtyp = ACTIVATE_MSG;
1184 
1185 	tipc_link_build_proto_msg(l, mtyp, 0, 0, 0, 0, xmitq);
1186 
1187 	/* Inform peer that this endpoint is going down if applicable */
1188 	skb = skb_peek_tail(xmitq);
1189 	if (skb && (l->state == LINK_RESET))
1190 		msg_set_peer_stopping(buf_msg(skb), 1);
1191 }
1192 
1193 /* tipc_link_build_nack_msg: prepare link nack message for transmission
1194  * Note that sending of broadcast NACK is coordinated among nodes, to
1195  * reduce the risk of NACK storms towards the sender
1196  */
1197 static int tipc_link_build_nack_msg(struct tipc_link *l,
1198 				    struct sk_buff_head *xmitq)
1199 {
1200 	u32 def_cnt = ++l->stats.deferred_recv;
1201 	int match1, match2;
1202 
1203 	if (link_is_bc_rcvlink(l)) {
1204 		match1 = def_cnt & 0xf;
1205 		match2 = tipc_own_addr(l->net) & 0xf;
1206 		if (match1 == match2)
1207 			return TIPC_LINK_SND_STATE;
1208 		return 0;
1209 	}
1210 
1211 	if ((skb_queue_len(&l->deferdq) == 1) || !(def_cnt % TIPC_NACK_INTV))
1212 		tipc_link_build_proto_msg(l, STATE_MSG, 0, 0, 0, 0, xmitq);
1213 	return 0;
1214 }
1215 
1216 /* tipc_link_rcv - process TIPC packets/messages arriving from off-node
1217  * @l: the link that should handle the message
1218  * @skb: TIPC packet
1219  * @xmitq: queue to place packets to be sent after this call
1220  */
1221 int tipc_link_rcv(struct tipc_link *l, struct sk_buff *skb,
1222 		  struct sk_buff_head *xmitq)
1223 {
1224 	struct sk_buff_head *defq = &l->deferdq;
1225 	struct tipc_msg *hdr;
1226 	u16 seqno, rcv_nxt, win_lim;
1227 	int rc = 0;
1228 
1229 	do {
1230 		hdr = buf_msg(skb);
1231 		seqno = msg_seqno(hdr);
1232 		rcv_nxt = l->rcv_nxt;
1233 		win_lim = rcv_nxt + TIPC_MAX_LINK_WIN;
1234 
1235 		/* Verify and update link state */
1236 		if (unlikely(msg_user(hdr) == LINK_PROTOCOL))
1237 			return tipc_link_proto_rcv(l, skb, xmitq);
1238 
1239 		if (unlikely(!link_is_up(l))) {
1240 			if (l->state == LINK_ESTABLISHING)
1241 				rc = TIPC_LINK_UP_EVT;
1242 			goto drop;
1243 		}
1244 
1245 		/* Don't send probe at next timeout expiration */
1246 		l->silent_intv_cnt = 0;
1247 
1248 		/* Drop if outside receive window */
1249 		if (unlikely(less(seqno, rcv_nxt) || more(seqno, win_lim))) {
1250 			l->stats.duplicates++;
1251 			goto drop;
1252 		}
1253 
1254 		/* Forward queues and wake up waiting users */
1255 		if (likely(tipc_link_release_pkts(l, msg_ack(hdr)))) {
1256 			tipc_link_advance_backlog(l, xmitq);
1257 			if (unlikely(!skb_queue_empty(&l->wakeupq)))
1258 				link_prepare_wakeup(l);
1259 		}
1260 
1261 		/* Defer delivery if sequence gap */
1262 		if (unlikely(seqno != rcv_nxt)) {
1263 			__tipc_skb_queue_sorted(defq, seqno, skb);
1264 			rc |= tipc_link_build_nack_msg(l, xmitq);
1265 			break;
1266 		}
1267 
1268 		/* Deliver packet */
1269 		l->rcv_nxt++;
1270 		l->stats.recv_pkts++;
1271 		if (!tipc_data_input(l, skb, l->inputq))
1272 			rc |= tipc_link_input(l, skb, l->inputq);
1273 		if (unlikely(++l->rcv_unacked >= TIPC_MIN_LINK_WIN))
1274 			rc |= tipc_link_build_state_msg(l, xmitq);
1275 		if (unlikely(rc & ~TIPC_LINK_SND_STATE))
1276 			break;
1277 	} while ((skb = __skb_dequeue(defq)));
1278 
1279 	return rc;
1280 drop:
1281 	kfree_skb(skb);
1282 	return rc;
1283 }
1284 
1285 static void tipc_link_build_proto_msg(struct tipc_link *l, int mtyp, bool probe,
1286 				      u16 rcvgap, int tolerance, int priority,
1287 				      struct sk_buff_head *xmitq)
1288 {
1289 	struct tipc_link *bcl = l->bc_rcvlink;
1290 	struct sk_buff *skb;
1291 	struct tipc_msg *hdr;
1292 	struct sk_buff_head *dfq = &l->deferdq;
1293 	bool node_up = link_is_up(bcl);
1294 	struct tipc_mon_state *mstate = &l->mon_state;
1295 	int dlen = 0;
1296 	void *data;
1297 
1298 	/* Don't send protocol message during reset or link failover */
1299 	if (tipc_link_is_blocked(l))
1300 		return;
1301 
1302 	if (!tipc_link_is_up(l) && (mtyp == STATE_MSG))
1303 		return;
1304 
1305 	if (!skb_queue_empty(dfq))
1306 		rcvgap = buf_seqno(skb_peek(dfq)) - l->rcv_nxt;
1307 
1308 	skb = tipc_msg_create(LINK_PROTOCOL, mtyp, INT_H_SIZE,
1309 			      tipc_max_domain_size, l->addr,
1310 			      tipc_own_addr(l->net), 0, 0, 0);
1311 	if (!skb)
1312 		return;
1313 
1314 	hdr = buf_msg(skb);
1315 	data = msg_data(hdr);
1316 	msg_set_session(hdr, l->session);
1317 	msg_set_bearer_id(hdr, l->bearer_id);
1318 	msg_set_net_plane(hdr, l->net_plane);
1319 	msg_set_next_sent(hdr, l->snd_nxt);
1320 	msg_set_ack(hdr, l->rcv_nxt - 1);
1321 	msg_set_bcast_ack(hdr, bcl->rcv_nxt - 1);
1322 	msg_set_bc_ack_invalid(hdr, !node_up);
1323 	msg_set_last_bcast(hdr, l->bc_sndlink->snd_nxt - 1);
1324 	msg_set_link_tolerance(hdr, tolerance);
1325 	msg_set_linkprio(hdr, priority);
1326 	msg_set_redundant_link(hdr, node_up);
1327 	msg_set_seq_gap(hdr, 0);
1328 	msg_set_seqno(hdr, l->snd_nxt + U16_MAX / 2);
1329 
1330 	if (mtyp == STATE_MSG) {
1331 		msg_set_seq_gap(hdr, rcvgap);
1332 		msg_set_bc_gap(hdr, link_bc_rcv_gap(bcl));
1333 		msg_set_probe(hdr, probe);
1334 		tipc_mon_prep(l->net, data, &dlen, mstate, l->bearer_id);
1335 		msg_set_size(hdr, INT_H_SIZE + dlen);
1336 		skb_trim(skb, INT_H_SIZE + dlen);
1337 		l->stats.sent_states++;
1338 		l->rcv_unacked = 0;
1339 	} else {
1340 		/* RESET_MSG or ACTIVATE_MSG */
1341 		msg_set_max_pkt(hdr, l->advertised_mtu);
1342 		strcpy(data, l->if_name);
1343 		msg_set_size(hdr, INT_H_SIZE + TIPC_MAX_IF_NAME);
1344 		skb_trim(skb, INT_H_SIZE + TIPC_MAX_IF_NAME);
1345 	}
1346 	if (probe)
1347 		l->stats.sent_probes++;
1348 	if (rcvgap)
1349 		l->stats.sent_nacks++;
1350 	skb->priority = TC_PRIO_CONTROL;
1351 	__skb_queue_tail(xmitq, skb);
1352 }
1353 
1354 /* tipc_link_tnl_prepare(): prepare and return a list of tunnel packets
1355  * with contents of the link's transmit and backlog queues.
1356  */
1357 void tipc_link_tnl_prepare(struct tipc_link *l, struct tipc_link *tnl,
1358 			   int mtyp, struct sk_buff_head *xmitq)
1359 {
1360 	struct sk_buff *skb, *tnlskb;
1361 	struct tipc_msg *hdr, tnlhdr;
1362 	struct sk_buff_head *queue = &l->transmq;
1363 	struct sk_buff_head tmpxq, tnlq;
1364 	u16 pktlen, pktcnt, seqno = l->snd_nxt;
1365 
1366 	if (!tnl)
1367 		return;
1368 
1369 	skb_queue_head_init(&tnlq);
1370 	skb_queue_head_init(&tmpxq);
1371 
1372 	/* At least one packet required for safe algorithm => add dummy */
1373 	skb = tipc_msg_create(TIPC_LOW_IMPORTANCE, TIPC_DIRECT_MSG,
1374 			      BASIC_H_SIZE, 0, l->addr, tipc_own_addr(l->net),
1375 			      0, 0, TIPC_ERR_NO_PORT);
1376 	if (!skb) {
1377 		pr_warn("%sunable to create tunnel packet\n", link_co_err);
1378 		return;
1379 	}
1380 	skb_queue_tail(&tnlq, skb);
1381 	tipc_link_xmit(l, &tnlq, &tmpxq);
1382 	__skb_queue_purge(&tmpxq);
1383 
1384 	/* Initialize reusable tunnel packet header */
1385 	tipc_msg_init(tipc_own_addr(l->net), &tnlhdr, TUNNEL_PROTOCOL,
1386 		      mtyp, INT_H_SIZE, l->addr);
1387 	pktcnt = skb_queue_len(&l->transmq) + skb_queue_len(&l->backlogq);
1388 	msg_set_msgcnt(&tnlhdr, pktcnt);
1389 	msg_set_bearer_id(&tnlhdr, l->peer_bearer_id);
1390 tnl:
1391 	/* Wrap each packet into a tunnel packet */
1392 	skb_queue_walk(queue, skb) {
1393 		hdr = buf_msg(skb);
1394 		if (queue == &l->backlogq)
1395 			msg_set_seqno(hdr, seqno++);
1396 		pktlen = msg_size(hdr);
1397 		msg_set_size(&tnlhdr, pktlen + INT_H_SIZE);
1398 		tnlskb = tipc_buf_acquire(pktlen + INT_H_SIZE, GFP_ATOMIC);
1399 		if (!tnlskb) {
1400 			pr_warn("%sunable to send packet\n", link_co_err);
1401 			return;
1402 		}
1403 		skb_copy_to_linear_data(tnlskb, &tnlhdr, INT_H_SIZE);
1404 		skb_copy_to_linear_data_offset(tnlskb, INT_H_SIZE, hdr, pktlen);
1405 		__skb_queue_tail(&tnlq, tnlskb);
1406 	}
1407 	if (queue != &l->backlogq) {
1408 		queue = &l->backlogq;
1409 		goto tnl;
1410 	}
1411 
1412 	tipc_link_xmit(tnl, &tnlq, xmitq);
1413 
1414 	if (mtyp == FAILOVER_MSG) {
1415 		tnl->drop_point = l->rcv_nxt;
1416 		tnl->failover_reasm_skb = l->reasm_buf;
1417 		l->reasm_buf = NULL;
1418 	}
1419 }
1420 
1421 /* tipc_link_proto_rcv(): receive link level protocol message :
1422  * Note that network plane id propagates through the network, and may
1423  * change at any time. The node with lowest numerical id determines
1424  * network plane
1425  */
1426 static int tipc_link_proto_rcv(struct tipc_link *l, struct sk_buff *skb,
1427 			       struct sk_buff_head *xmitq)
1428 {
1429 	struct tipc_msg *hdr = buf_msg(skb);
1430 	u16 rcvgap = 0;
1431 	u16 ack = msg_ack(hdr);
1432 	u16 gap = msg_seq_gap(hdr);
1433 	u16 peers_snd_nxt =  msg_next_sent(hdr);
1434 	u16 peers_tol = msg_link_tolerance(hdr);
1435 	u16 peers_prio = msg_linkprio(hdr);
1436 	u16 rcv_nxt = l->rcv_nxt;
1437 	u16 dlen = msg_data_sz(hdr);
1438 	int mtyp = msg_type(hdr);
1439 	void *data;
1440 	char *if_name;
1441 	int rc = 0;
1442 
1443 	if (tipc_link_is_blocked(l) || !xmitq)
1444 		goto exit;
1445 
1446 	if (tipc_own_addr(l->net) > msg_prevnode(hdr))
1447 		l->net_plane = msg_net_plane(hdr);
1448 
1449 	skb_linearize(skb);
1450 	hdr = buf_msg(skb);
1451 	data = msg_data(hdr);
1452 
1453 	switch (mtyp) {
1454 	case RESET_MSG:
1455 
1456 		/* Ignore duplicate RESET with old session number */
1457 		if ((less_eq(msg_session(hdr), l->peer_session)) &&
1458 		    (l->peer_session != ANY_SESSION))
1459 			break;
1460 		/* fall thru' */
1461 
1462 	case ACTIVATE_MSG:
1463 
1464 		/* Complete own link name with peer's interface name */
1465 		if_name =  strrchr(l->name, ':') + 1;
1466 		if (sizeof(l->name) - (if_name - l->name) <= TIPC_MAX_IF_NAME)
1467 			break;
1468 		if (msg_data_sz(hdr) < TIPC_MAX_IF_NAME)
1469 			break;
1470 		strncpy(if_name, data, TIPC_MAX_IF_NAME);
1471 
1472 		/* Update own tolerance if peer indicates a non-zero value */
1473 		if (in_range(peers_tol, TIPC_MIN_LINK_TOL, TIPC_MAX_LINK_TOL))
1474 			l->tolerance = peers_tol;
1475 
1476 		/* Update own priority if peer's priority is higher */
1477 		if (in_range(peers_prio, l->priority + 1, TIPC_MAX_LINK_PRI))
1478 			l->priority = peers_prio;
1479 
1480 		/* ACTIVATE_MSG serves as PEER_RESET if link is already down */
1481 		if (msg_peer_stopping(hdr))
1482 			rc = tipc_link_fsm_evt(l, LINK_FAILURE_EVT);
1483 		else if ((mtyp == RESET_MSG) || !link_is_up(l))
1484 			rc = tipc_link_fsm_evt(l, LINK_PEER_RESET_EVT);
1485 
1486 		/* ACTIVATE_MSG takes up link if it was already locally reset */
1487 		if ((mtyp == ACTIVATE_MSG) && (l->state == LINK_ESTABLISHING))
1488 			rc = TIPC_LINK_UP_EVT;
1489 
1490 		l->peer_session = msg_session(hdr);
1491 		l->peer_bearer_id = msg_bearer_id(hdr);
1492 		if (l->mtu > msg_max_pkt(hdr))
1493 			l->mtu = msg_max_pkt(hdr);
1494 		break;
1495 
1496 	case STATE_MSG:
1497 
1498 		/* Update own tolerance if peer indicates a non-zero value */
1499 		if (in_range(peers_tol, TIPC_MIN_LINK_TOL, TIPC_MAX_LINK_TOL))
1500 			l->tolerance = peers_tol;
1501 
1502 		/* Update own prio if peer indicates a different value */
1503 		if ((peers_prio != l->priority) &&
1504 		    in_range(peers_prio, 1, TIPC_MAX_LINK_PRI)) {
1505 			l->priority = peers_prio;
1506 			rc = tipc_link_fsm_evt(l, LINK_FAILURE_EVT);
1507 		}
1508 
1509 		l->silent_intv_cnt = 0;
1510 		l->stats.recv_states++;
1511 		if (msg_probe(hdr))
1512 			l->stats.recv_probes++;
1513 
1514 		if (!link_is_up(l)) {
1515 			if (l->state == LINK_ESTABLISHING)
1516 				rc = TIPC_LINK_UP_EVT;
1517 			break;
1518 		}
1519 		tipc_mon_rcv(l->net, data, dlen, l->addr,
1520 			     &l->mon_state, l->bearer_id);
1521 
1522 		/* Send NACK if peer has sent pkts we haven't received yet */
1523 		if (more(peers_snd_nxt, rcv_nxt) && !tipc_link_is_synching(l))
1524 			rcvgap = peers_snd_nxt - l->rcv_nxt;
1525 		if (rcvgap || (msg_probe(hdr)))
1526 			tipc_link_build_proto_msg(l, STATE_MSG, 0, rcvgap,
1527 						  0, 0, xmitq);
1528 		tipc_link_release_pkts(l, ack);
1529 
1530 		/* If NACK, retransmit will now start at right position */
1531 		if (gap) {
1532 			rc = tipc_link_retrans(l, ack + 1, ack + gap, xmitq);
1533 			l->stats.recv_nacks++;
1534 		}
1535 
1536 		tipc_link_advance_backlog(l, xmitq);
1537 		if (unlikely(!skb_queue_empty(&l->wakeupq)))
1538 			link_prepare_wakeup(l);
1539 	}
1540 exit:
1541 	kfree_skb(skb);
1542 	return rc;
1543 }
1544 
1545 /* tipc_link_build_bc_proto_msg() - create broadcast protocol message
1546  */
1547 static bool tipc_link_build_bc_proto_msg(struct tipc_link *l, bool bcast,
1548 					 u16 peers_snd_nxt,
1549 					 struct sk_buff_head *xmitq)
1550 {
1551 	struct sk_buff *skb;
1552 	struct tipc_msg *hdr;
1553 	struct sk_buff *dfrd_skb = skb_peek(&l->deferdq);
1554 	u16 ack = l->rcv_nxt - 1;
1555 	u16 gap_to = peers_snd_nxt - 1;
1556 
1557 	skb = tipc_msg_create(BCAST_PROTOCOL, STATE_MSG, INT_H_SIZE,
1558 			      0, l->addr, tipc_own_addr(l->net), 0, 0, 0);
1559 	if (!skb)
1560 		return false;
1561 	hdr = buf_msg(skb);
1562 	msg_set_last_bcast(hdr, l->bc_sndlink->snd_nxt - 1);
1563 	msg_set_bcast_ack(hdr, ack);
1564 	msg_set_bcgap_after(hdr, ack);
1565 	if (dfrd_skb)
1566 		gap_to = buf_seqno(dfrd_skb) - 1;
1567 	msg_set_bcgap_to(hdr, gap_to);
1568 	msg_set_non_seq(hdr, bcast);
1569 	__skb_queue_tail(xmitq, skb);
1570 	return true;
1571 }
1572 
1573 /* tipc_link_build_bc_init_msg() - synchronize broadcast link endpoints.
1574  *
1575  * Give a newly added peer node the sequence number where it should
1576  * start receiving and acking broadcast packets.
1577  */
1578 static void tipc_link_build_bc_init_msg(struct tipc_link *l,
1579 					struct sk_buff_head *xmitq)
1580 {
1581 	struct sk_buff_head list;
1582 
1583 	__skb_queue_head_init(&list);
1584 	if (!tipc_link_build_bc_proto_msg(l->bc_rcvlink, false, 0, &list))
1585 		return;
1586 	msg_set_bc_ack_invalid(buf_msg(skb_peek(&list)), true);
1587 	tipc_link_xmit(l, &list, xmitq);
1588 }
1589 
1590 /* tipc_link_bc_init_rcv - receive initial broadcast synch data from peer
1591  */
1592 void tipc_link_bc_init_rcv(struct tipc_link *l, struct tipc_msg *hdr)
1593 {
1594 	int mtyp = msg_type(hdr);
1595 	u16 peers_snd_nxt = msg_bc_snd_nxt(hdr);
1596 
1597 	if (link_is_up(l))
1598 		return;
1599 
1600 	if (msg_user(hdr) == BCAST_PROTOCOL) {
1601 		l->rcv_nxt = peers_snd_nxt;
1602 		l->state = LINK_ESTABLISHED;
1603 		return;
1604 	}
1605 
1606 	if (l->peer_caps & TIPC_BCAST_SYNCH)
1607 		return;
1608 
1609 	if (msg_peer_node_is_up(hdr))
1610 		return;
1611 
1612 	/* Compatibility: accept older, less safe initial synch data */
1613 	if ((mtyp == RESET_MSG) || (mtyp == ACTIVATE_MSG))
1614 		l->rcv_nxt = peers_snd_nxt;
1615 }
1616 
1617 /* link_bc_retr eval()- check if the indicated range can be retransmitted now
1618  * - Adjust permitted range if there is overlap with previous retransmission
1619  */
1620 static bool link_bc_retr_eval(struct tipc_link *l, u16 *from, u16 *to)
1621 {
1622 	unsigned long elapsed = jiffies_to_msecs(jiffies - l->prev_retr);
1623 
1624 	if (less(*to, *from))
1625 		return false;
1626 
1627 	/* New retransmission request */
1628 	if ((elapsed > TIPC_BC_RETR_LIMIT) ||
1629 	    less(*to, l->prev_from) || more(*from, l->prev_to)) {
1630 		l->prev_from = *from;
1631 		l->prev_to = *to;
1632 		l->prev_retr = jiffies;
1633 		return true;
1634 	}
1635 
1636 	/* Inside range of previous retransmit */
1637 	if (!less(*from, l->prev_from) && !more(*to, l->prev_to))
1638 		return false;
1639 
1640 	/* Fully or partially outside previous range => exclude overlap */
1641 	if (less(*from, l->prev_from)) {
1642 		*to = l->prev_from - 1;
1643 		l->prev_from = *from;
1644 	}
1645 	if (more(*to, l->prev_to)) {
1646 		*from = l->prev_to + 1;
1647 		l->prev_to = *to;
1648 	}
1649 	l->prev_retr = jiffies;
1650 	return true;
1651 }
1652 
1653 /* tipc_link_bc_sync_rcv - update rcv link according to peer's send state
1654  */
1655 int tipc_link_bc_sync_rcv(struct tipc_link *l, struct tipc_msg *hdr,
1656 			  struct sk_buff_head *xmitq)
1657 {
1658 	struct tipc_link *snd_l = l->bc_sndlink;
1659 	u16 peers_snd_nxt = msg_bc_snd_nxt(hdr);
1660 	u16 from = msg_bcast_ack(hdr) + 1;
1661 	u16 to = from + msg_bc_gap(hdr) - 1;
1662 	int rc = 0;
1663 
1664 	if (!link_is_up(l))
1665 		return rc;
1666 
1667 	if (!msg_peer_node_is_up(hdr))
1668 		return rc;
1669 
1670 	/* Open when peer ackowledges our bcast init msg (pkt #1) */
1671 	if (msg_ack(hdr))
1672 		l->bc_peer_is_up = true;
1673 
1674 	if (!l->bc_peer_is_up)
1675 		return rc;
1676 
1677 	l->stats.recv_nacks++;
1678 
1679 	/* Ignore if peers_snd_nxt goes beyond receive window */
1680 	if (more(peers_snd_nxt, l->rcv_nxt + l->window))
1681 		return rc;
1682 
1683 	if (link_bc_retr_eval(snd_l, &from, &to))
1684 		rc = tipc_link_retrans(snd_l, from, to, xmitq);
1685 
1686 	l->snd_nxt = peers_snd_nxt;
1687 	if (link_bc_rcv_gap(l))
1688 		rc |= TIPC_LINK_SND_STATE;
1689 
1690 	/* Return now if sender supports nack via STATE messages */
1691 	if (l->peer_caps & TIPC_BCAST_STATE_NACK)
1692 		return rc;
1693 
1694 	/* Otherwise, be backwards compatible */
1695 
1696 	if (!more(peers_snd_nxt, l->rcv_nxt)) {
1697 		l->nack_state = BC_NACK_SND_CONDITIONAL;
1698 		return 0;
1699 	}
1700 
1701 	/* Don't NACK if one was recently sent or peeked */
1702 	if (l->nack_state == BC_NACK_SND_SUPPRESS) {
1703 		l->nack_state = BC_NACK_SND_UNCONDITIONAL;
1704 		return 0;
1705 	}
1706 
1707 	/* Conditionally delay NACK sending until next synch rcv */
1708 	if (l->nack_state == BC_NACK_SND_CONDITIONAL) {
1709 		l->nack_state = BC_NACK_SND_UNCONDITIONAL;
1710 		if ((peers_snd_nxt - l->rcv_nxt) < TIPC_MIN_LINK_WIN)
1711 			return 0;
1712 	}
1713 
1714 	/* Send NACK now but suppress next one */
1715 	tipc_link_build_bc_proto_msg(l, true, peers_snd_nxt, xmitq);
1716 	l->nack_state = BC_NACK_SND_SUPPRESS;
1717 	return 0;
1718 }
1719 
1720 void tipc_link_bc_ack_rcv(struct tipc_link *l, u16 acked,
1721 			  struct sk_buff_head *xmitq)
1722 {
1723 	struct sk_buff *skb, *tmp;
1724 	struct tipc_link *snd_l = l->bc_sndlink;
1725 
1726 	if (!link_is_up(l) || !l->bc_peer_is_up)
1727 		return;
1728 
1729 	if (!more(acked, l->acked))
1730 		return;
1731 
1732 	/* Skip over packets peer has already acked */
1733 	skb_queue_walk(&snd_l->transmq, skb) {
1734 		if (more(buf_seqno(skb), l->acked))
1735 			break;
1736 	}
1737 
1738 	/* Update/release the packets peer is acking now */
1739 	skb_queue_walk_from_safe(&snd_l->transmq, skb, tmp) {
1740 		if (more(buf_seqno(skb), acked))
1741 			break;
1742 		if (!--TIPC_SKB_CB(skb)->ackers) {
1743 			__skb_unlink(skb, &snd_l->transmq);
1744 			kfree_skb(skb);
1745 		}
1746 	}
1747 	l->acked = acked;
1748 	tipc_link_advance_backlog(snd_l, xmitq);
1749 	if (unlikely(!skb_queue_empty(&snd_l->wakeupq)))
1750 		link_prepare_wakeup(snd_l);
1751 }
1752 
1753 /* tipc_link_bc_nack_rcv(): receive broadcast nack message
1754  * This function is here for backwards compatibility, since
1755  * no BCAST_PROTOCOL/STATE messages occur from TIPC v2.5.
1756  */
1757 int tipc_link_bc_nack_rcv(struct tipc_link *l, struct sk_buff *skb,
1758 			  struct sk_buff_head *xmitq)
1759 {
1760 	struct tipc_msg *hdr = buf_msg(skb);
1761 	u32 dnode = msg_destnode(hdr);
1762 	int mtyp = msg_type(hdr);
1763 	u16 acked = msg_bcast_ack(hdr);
1764 	u16 from = acked + 1;
1765 	u16 to = msg_bcgap_to(hdr);
1766 	u16 peers_snd_nxt = to + 1;
1767 	int rc = 0;
1768 
1769 	kfree_skb(skb);
1770 
1771 	if (!tipc_link_is_up(l) || !l->bc_peer_is_up)
1772 		return 0;
1773 
1774 	if (mtyp != STATE_MSG)
1775 		return 0;
1776 
1777 	if (dnode == tipc_own_addr(l->net)) {
1778 		tipc_link_bc_ack_rcv(l, acked, xmitq);
1779 		rc = tipc_link_retrans(l->bc_sndlink, from, to, xmitq);
1780 		l->stats.recv_nacks++;
1781 		return rc;
1782 	}
1783 
1784 	/* Msg for other node => suppress own NACK at next sync if applicable */
1785 	if (more(peers_snd_nxt, l->rcv_nxt) && !less(l->rcv_nxt, from))
1786 		l->nack_state = BC_NACK_SND_SUPPRESS;
1787 
1788 	return 0;
1789 }
1790 
1791 void tipc_link_set_queue_limits(struct tipc_link *l, u32 win)
1792 {
1793 	int max_bulk = TIPC_MAX_PUBLICATIONS / (l->mtu / ITEM_SIZE);
1794 
1795 	l->window = win;
1796 	l->backlog[TIPC_LOW_IMPORTANCE].limit      = max_t(u16, 50, win);
1797 	l->backlog[TIPC_MEDIUM_IMPORTANCE].limit   = max_t(u16, 100, win * 2);
1798 	l->backlog[TIPC_HIGH_IMPORTANCE].limit     = max_t(u16, 150, win * 3);
1799 	l->backlog[TIPC_CRITICAL_IMPORTANCE].limit = max_t(u16, 200, win * 4);
1800 	l->backlog[TIPC_SYSTEM_IMPORTANCE].limit   = max_bulk;
1801 }
1802 
1803 /**
1804  * link_reset_stats - reset link statistics
1805  * @l: pointer to link
1806  */
1807 void tipc_link_reset_stats(struct tipc_link *l)
1808 {
1809 	memset(&l->stats, 0, sizeof(l->stats));
1810 }
1811 
1812 static void link_print(struct tipc_link *l, const char *str)
1813 {
1814 	struct sk_buff *hskb = skb_peek(&l->transmq);
1815 	u16 head = hskb ? msg_seqno(buf_msg(hskb)) : l->snd_nxt - 1;
1816 	u16 tail = l->snd_nxt - 1;
1817 
1818 	pr_info("%s Link <%s> state %x\n", str, l->name, l->state);
1819 	pr_info("XMTQ: %u [%u-%u], BKLGQ: %u, SNDNX: %u, RCVNX: %u\n",
1820 		skb_queue_len(&l->transmq), head, tail,
1821 		skb_queue_len(&l->backlogq), l->snd_nxt, l->rcv_nxt);
1822 }
1823 
1824 /* Parse and validate nested (link) properties valid for media, bearer and link
1825  */
1826 int tipc_nl_parse_link_prop(struct nlattr *prop, struct nlattr *props[])
1827 {
1828 	int err;
1829 
1830 	err = nla_parse_nested(props, TIPC_NLA_PROP_MAX, prop,
1831 			       tipc_nl_prop_policy);
1832 	if (err)
1833 		return err;
1834 
1835 	if (props[TIPC_NLA_PROP_PRIO]) {
1836 		u32 prio;
1837 
1838 		prio = nla_get_u32(props[TIPC_NLA_PROP_PRIO]);
1839 		if (prio > TIPC_MAX_LINK_PRI)
1840 			return -EINVAL;
1841 	}
1842 
1843 	if (props[TIPC_NLA_PROP_TOL]) {
1844 		u32 tol;
1845 
1846 		tol = nla_get_u32(props[TIPC_NLA_PROP_TOL]);
1847 		if ((tol < TIPC_MIN_LINK_TOL) || (tol > TIPC_MAX_LINK_TOL))
1848 			return -EINVAL;
1849 	}
1850 
1851 	if (props[TIPC_NLA_PROP_WIN]) {
1852 		u32 win;
1853 
1854 		win = nla_get_u32(props[TIPC_NLA_PROP_WIN]);
1855 		if ((win < TIPC_MIN_LINK_WIN) || (win > TIPC_MAX_LINK_WIN))
1856 			return -EINVAL;
1857 	}
1858 
1859 	return 0;
1860 }
1861 
1862 static int __tipc_nl_add_stats(struct sk_buff *skb, struct tipc_stats *s)
1863 {
1864 	int i;
1865 	struct nlattr *stats;
1866 
1867 	struct nla_map {
1868 		u32 key;
1869 		u32 val;
1870 	};
1871 
1872 	struct nla_map map[] = {
1873 		{TIPC_NLA_STATS_RX_INFO, 0},
1874 		{TIPC_NLA_STATS_RX_FRAGMENTS, s->recv_fragments},
1875 		{TIPC_NLA_STATS_RX_FRAGMENTED, s->recv_fragmented},
1876 		{TIPC_NLA_STATS_RX_BUNDLES, s->recv_bundles},
1877 		{TIPC_NLA_STATS_RX_BUNDLED, s->recv_bundled},
1878 		{TIPC_NLA_STATS_TX_INFO, 0},
1879 		{TIPC_NLA_STATS_TX_FRAGMENTS, s->sent_fragments},
1880 		{TIPC_NLA_STATS_TX_FRAGMENTED, s->sent_fragmented},
1881 		{TIPC_NLA_STATS_TX_BUNDLES, s->sent_bundles},
1882 		{TIPC_NLA_STATS_TX_BUNDLED, s->sent_bundled},
1883 		{TIPC_NLA_STATS_MSG_PROF_TOT, (s->msg_length_counts) ?
1884 			s->msg_length_counts : 1},
1885 		{TIPC_NLA_STATS_MSG_LEN_CNT, s->msg_length_counts},
1886 		{TIPC_NLA_STATS_MSG_LEN_TOT, s->msg_lengths_total},
1887 		{TIPC_NLA_STATS_MSG_LEN_P0, s->msg_length_profile[0]},
1888 		{TIPC_NLA_STATS_MSG_LEN_P1, s->msg_length_profile[1]},
1889 		{TIPC_NLA_STATS_MSG_LEN_P2, s->msg_length_profile[2]},
1890 		{TIPC_NLA_STATS_MSG_LEN_P3, s->msg_length_profile[3]},
1891 		{TIPC_NLA_STATS_MSG_LEN_P4, s->msg_length_profile[4]},
1892 		{TIPC_NLA_STATS_MSG_LEN_P5, s->msg_length_profile[5]},
1893 		{TIPC_NLA_STATS_MSG_LEN_P6, s->msg_length_profile[6]},
1894 		{TIPC_NLA_STATS_RX_STATES, s->recv_states},
1895 		{TIPC_NLA_STATS_RX_PROBES, s->recv_probes},
1896 		{TIPC_NLA_STATS_RX_NACKS, s->recv_nacks},
1897 		{TIPC_NLA_STATS_RX_DEFERRED, s->deferred_recv},
1898 		{TIPC_NLA_STATS_TX_STATES, s->sent_states},
1899 		{TIPC_NLA_STATS_TX_PROBES, s->sent_probes},
1900 		{TIPC_NLA_STATS_TX_NACKS, s->sent_nacks},
1901 		{TIPC_NLA_STATS_TX_ACKS, s->sent_acks},
1902 		{TIPC_NLA_STATS_RETRANSMITTED, s->retransmitted},
1903 		{TIPC_NLA_STATS_DUPLICATES, s->duplicates},
1904 		{TIPC_NLA_STATS_LINK_CONGS, s->link_congs},
1905 		{TIPC_NLA_STATS_MAX_QUEUE, s->max_queue_sz},
1906 		{TIPC_NLA_STATS_AVG_QUEUE, s->queue_sz_counts ?
1907 			(s->accu_queue_sz / s->queue_sz_counts) : 0}
1908 	};
1909 
1910 	stats = nla_nest_start(skb, TIPC_NLA_LINK_STATS);
1911 	if (!stats)
1912 		return -EMSGSIZE;
1913 
1914 	for (i = 0; i <  ARRAY_SIZE(map); i++)
1915 		if (nla_put_u32(skb, map[i].key, map[i].val))
1916 			goto msg_full;
1917 
1918 	nla_nest_end(skb, stats);
1919 
1920 	return 0;
1921 msg_full:
1922 	nla_nest_cancel(skb, stats);
1923 
1924 	return -EMSGSIZE;
1925 }
1926 
1927 /* Caller should hold appropriate locks to protect the link */
1928 int __tipc_nl_add_link(struct net *net, struct tipc_nl_msg *msg,
1929 		       struct tipc_link *link, int nlflags)
1930 {
1931 	int err;
1932 	void *hdr;
1933 	struct nlattr *attrs;
1934 	struct nlattr *prop;
1935 	struct tipc_net *tn = net_generic(net, tipc_net_id);
1936 
1937 	hdr = genlmsg_put(msg->skb, msg->portid, msg->seq, &tipc_genl_family,
1938 			  nlflags, TIPC_NL_LINK_GET);
1939 	if (!hdr)
1940 		return -EMSGSIZE;
1941 
1942 	attrs = nla_nest_start(msg->skb, TIPC_NLA_LINK);
1943 	if (!attrs)
1944 		goto msg_full;
1945 
1946 	if (nla_put_string(msg->skb, TIPC_NLA_LINK_NAME, link->name))
1947 		goto attr_msg_full;
1948 	if (nla_put_u32(msg->skb, TIPC_NLA_LINK_DEST,
1949 			tipc_cluster_mask(tn->own_addr)))
1950 		goto attr_msg_full;
1951 	if (nla_put_u32(msg->skb, TIPC_NLA_LINK_MTU, link->mtu))
1952 		goto attr_msg_full;
1953 	if (nla_put_u32(msg->skb, TIPC_NLA_LINK_RX, link->stats.recv_pkts))
1954 		goto attr_msg_full;
1955 	if (nla_put_u32(msg->skb, TIPC_NLA_LINK_TX, link->stats.sent_pkts))
1956 		goto attr_msg_full;
1957 
1958 	if (tipc_link_is_up(link))
1959 		if (nla_put_flag(msg->skb, TIPC_NLA_LINK_UP))
1960 			goto attr_msg_full;
1961 	if (link->active)
1962 		if (nla_put_flag(msg->skb, TIPC_NLA_LINK_ACTIVE))
1963 			goto attr_msg_full;
1964 
1965 	prop = nla_nest_start(msg->skb, TIPC_NLA_LINK_PROP);
1966 	if (!prop)
1967 		goto attr_msg_full;
1968 	if (nla_put_u32(msg->skb, TIPC_NLA_PROP_PRIO, link->priority))
1969 		goto prop_msg_full;
1970 	if (nla_put_u32(msg->skb, TIPC_NLA_PROP_TOL, link->tolerance))
1971 		goto prop_msg_full;
1972 	if (nla_put_u32(msg->skb, TIPC_NLA_PROP_WIN,
1973 			link->window))
1974 		goto prop_msg_full;
1975 	if (nla_put_u32(msg->skb, TIPC_NLA_PROP_PRIO, link->priority))
1976 		goto prop_msg_full;
1977 	nla_nest_end(msg->skb, prop);
1978 
1979 	err = __tipc_nl_add_stats(msg->skb, &link->stats);
1980 	if (err)
1981 		goto attr_msg_full;
1982 
1983 	nla_nest_end(msg->skb, attrs);
1984 	genlmsg_end(msg->skb, hdr);
1985 
1986 	return 0;
1987 
1988 prop_msg_full:
1989 	nla_nest_cancel(msg->skb, prop);
1990 attr_msg_full:
1991 	nla_nest_cancel(msg->skb, attrs);
1992 msg_full:
1993 	genlmsg_cancel(msg->skb, hdr);
1994 
1995 	return -EMSGSIZE;
1996 }
1997 
1998 static int __tipc_nl_add_bc_link_stat(struct sk_buff *skb,
1999 				      struct tipc_stats *stats)
2000 {
2001 	int i;
2002 	struct nlattr *nest;
2003 
2004 	struct nla_map {
2005 		__u32 key;
2006 		__u32 val;
2007 	};
2008 
2009 	struct nla_map map[] = {
2010 		{TIPC_NLA_STATS_RX_INFO, stats->recv_pkts},
2011 		{TIPC_NLA_STATS_RX_FRAGMENTS, stats->recv_fragments},
2012 		{TIPC_NLA_STATS_RX_FRAGMENTED, stats->recv_fragmented},
2013 		{TIPC_NLA_STATS_RX_BUNDLES, stats->recv_bundles},
2014 		{TIPC_NLA_STATS_RX_BUNDLED, stats->recv_bundled},
2015 		{TIPC_NLA_STATS_TX_INFO, stats->sent_pkts},
2016 		{TIPC_NLA_STATS_TX_FRAGMENTS, stats->sent_fragments},
2017 		{TIPC_NLA_STATS_TX_FRAGMENTED, stats->sent_fragmented},
2018 		{TIPC_NLA_STATS_TX_BUNDLES, stats->sent_bundles},
2019 		{TIPC_NLA_STATS_TX_BUNDLED, stats->sent_bundled},
2020 		{TIPC_NLA_STATS_RX_NACKS, stats->recv_nacks},
2021 		{TIPC_NLA_STATS_RX_DEFERRED, stats->deferred_recv},
2022 		{TIPC_NLA_STATS_TX_NACKS, stats->sent_nacks},
2023 		{TIPC_NLA_STATS_TX_ACKS, stats->sent_acks},
2024 		{TIPC_NLA_STATS_RETRANSMITTED, stats->retransmitted},
2025 		{TIPC_NLA_STATS_DUPLICATES, stats->duplicates},
2026 		{TIPC_NLA_STATS_LINK_CONGS, stats->link_congs},
2027 		{TIPC_NLA_STATS_MAX_QUEUE, stats->max_queue_sz},
2028 		{TIPC_NLA_STATS_AVG_QUEUE, stats->queue_sz_counts ?
2029 			(stats->accu_queue_sz / stats->queue_sz_counts) : 0}
2030 	};
2031 
2032 	nest = nla_nest_start(skb, TIPC_NLA_LINK_STATS);
2033 	if (!nest)
2034 		return -EMSGSIZE;
2035 
2036 	for (i = 0; i <  ARRAY_SIZE(map); i++)
2037 		if (nla_put_u32(skb, map[i].key, map[i].val))
2038 			goto msg_full;
2039 
2040 	nla_nest_end(skb, nest);
2041 
2042 	return 0;
2043 msg_full:
2044 	nla_nest_cancel(skb, nest);
2045 
2046 	return -EMSGSIZE;
2047 }
2048 
2049 int tipc_nl_add_bc_link(struct net *net, struct tipc_nl_msg *msg)
2050 {
2051 	int err;
2052 	void *hdr;
2053 	struct nlattr *attrs;
2054 	struct nlattr *prop;
2055 	struct tipc_net *tn = net_generic(net, tipc_net_id);
2056 	struct tipc_link *bcl = tn->bcl;
2057 
2058 	if (!bcl)
2059 		return 0;
2060 
2061 	tipc_bcast_lock(net);
2062 
2063 	hdr = genlmsg_put(msg->skb, msg->portid, msg->seq, &tipc_genl_family,
2064 			  NLM_F_MULTI, TIPC_NL_LINK_GET);
2065 	if (!hdr) {
2066 		tipc_bcast_unlock(net);
2067 		return -EMSGSIZE;
2068 	}
2069 
2070 	attrs = nla_nest_start(msg->skb, TIPC_NLA_LINK);
2071 	if (!attrs)
2072 		goto msg_full;
2073 
2074 	/* The broadcast link is always up */
2075 	if (nla_put_flag(msg->skb, TIPC_NLA_LINK_UP))
2076 		goto attr_msg_full;
2077 
2078 	if (nla_put_flag(msg->skb, TIPC_NLA_LINK_BROADCAST))
2079 		goto attr_msg_full;
2080 	if (nla_put_string(msg->skb, TIPC_NLA_LINK_NAME, bcl->name))
2081 		goto attr_msg_full;
2082 	if (nla_put_u32(msg->skb, TIPC_NLA_LINK_RX, 0))
2083 		goto attr_msg_full;
2084 	if (nla_put_u32(msg->skb, TIPC_NLA_LINK_TX, 0))
2085 		goto attr_msg_full;
2086 
2087 	prop = nla_nest_start(msg->skb, TIPC_NLA_LINK_PROP);
2088 	if (!prop)
2089 		goto attr_msg_full;
2090 	if (nla_put_u32(msg->skb, TIPC_NLA_PROP_WIN, bcl->window))
2091 		goto prop_msg_full;
2092 	nla_nest_end(msg->skb, prop);
2093 
2094 	err = __tipc_nl_add_bc_link_stat(msg->skb, &bcl->stats);
2095 	if (err)
2096 		goto attr_msg_full;
2097 
2098 	tipc_bcast_unlock(net);
2099 	nla_nest_end(msg->skb, attrs);
2100 	genlmsg_end(msg->skb, hdr);
2101 
2102 	return 0;
2103 
2104 prop_msg_full:
2105 	nla_nest_cancel(msg->skb, prop);
2106 attr_msg_full:
2107 	nla_nest_cancel(msg->skb, attrs);
2108 msg_full:
2109 	tipc_bcast_unlock(net);
2110 	genlmsg_cancel(msg->skb, hdr);
2111 
2112 	return -EMSGSIZE;
2113 }
2114 
2115 void tipc_link_set_tolerance(struct tipc_link *l, u32 tol,
2116 			     struct sk_buff_head *xmitq)
2117 {
2118 	l->tolerance = tol;
2119 	tipc_link_build_proto_msg(l, STATE_MSG, 0, 0, tol, 0, xmitq);
2120 }
2121 
2122 void tipc_link_set_prio(struct tipc_link *l, u32 prio,
2123 			struct sk_buff_head *xmitq)
2124 {
2125 	l->priority = prio;
2126 	tipc_link_build_proto_msg(l, STATE_MSG, 0, 0, 0, prio, xmitq);
2127 }
2128 
2129 void tipc_link_set_abort_limit(struct tipc_link *l, u32 limit)
2130 {
2131 	l->abort_limit = limit;
2132 }
2133