xref: /linux/net/tipc/link.c (revision e96fddb32931d007db12b1fce9b5e8e4c080401b)
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 #include "trace.h"
47 #include "crypto.h"
48 
49 #include <linux/pkt_sched.h>
50 
51 struct tipc_stats {
52 	u32 sent_pkts;
53 	u32 recv_pkts;
54 	u32 sent_states;
55 	u32 recv_states;
56 	u32 sent_probes;
57 	u32 recv_probes;
58 	u32 sent_nacks;
59 	u32 recv_nacks;
60 	u32 sent_acks;
61 	u32 sent_bundled;
62 	u32 sent_bundles;
63 	u32 recv_bundled;
64 	u32 recv_bundles;
65 	u32 retransmitted;
66 	u32 sent_fragmented;
67 	u32 sent_fragments;
68 	u32 recv_fragmented;
69 	u32 recv_fragments;
70 	u32 link_congs;		/* # port sends blocked by congestion */
71 	u32 deferred_recv;
72 	u32 duplicates;
73 	u32 max_queue_sz;	/* send queue size high water mark */
74 	u32 accu_queue_sz;	/* used for send queue size profiling */
75 	u32 queue_sz_counts;	/* used for send queue size profiling */
76 	u32 msg_length_counts;	/* used for message length profiling */
77 	u32 msg_lengths_total;	/* used for message length profiling */
78 	u32 msg_length_profile[7]; /* used for msg. length profiling */
79 };
80 
81 /**
82  * struct tipc_link - TIPC link data structure
83  * @addr: network address of link's peer node
84  * @name: link name character string
85  * @net: pointer to namespace struct
86  * @peer_session: link session # being used by peer end of link
87  * @peer_bearer_id: bearer id used by link's peer endpoint
88  * @bearer_id: local bearer id used by link
89  * @tolerance: minimum link continuity loss needed to reset link [in ms]
90  * @abort_limit: # of unacknowledged continuity probes needed to reset link
91  * @state: current state of link FSM
92  * @peer_caps: bitmap describing capabilities of peer node
93  * @silent_intv_cnt: # of timer intervals without any reception from peer
94  * @priority: current link priority
95  * @net_plane: current link network plane ('A' through 'H')
96  * @mon_state: cookie with information needed by link monitor
97  * @mtu: current maximum packet size for this link
98  * @advertised_mtu: advertised own mtu when link is being established
99  * @backlogq: queue for messages waiting to be sent
100  * @ackers: # of peers that needs to ack each packet before it can be released
101  * @acked: # last packet acked by a certain peer. Used for broadcast.
102  * @rcv_nxt: next sequence number to expect for inbound messages
103  * @inputq: buffer queue for messages to be delivered upwards
104  * @namedq: buffer queue for name table messages to be delivered upwards
105  * @wakeupq: linked list of wakeup msgs waiting for link congestion to abate
106  * @reasm_buf: head of partially reassembled inbound message fragments
107  * @stats: collects statistics regarding link activity
108  * @session: session to be used by link
109  * @snd_nxt_state: next send seq number
110  * @rcv_nxt_state: next rcv seq number
111  * @in_session: have received ACTIVATE_MSG from peer
112  * @active: link is active
113  * @if_name: associated interface name
114  * @rst_cnt: link reset counter
115  * @drop_point: seq number for failover handling (FIXME)
116  * @failover_reasm_skb: saved failover msg ptr (FIXME)
117  * @failover_deferdq: deferred message queue for failover processing (FIXME)
118  * @transmq: the link's transmit queue
119  * @backlog: link's backlog by priority (importance)
120  * @snd_nxt: next sequence number to be used
121  * @rcv_unacked: # messages read by user, but not yet acked back to peer
122  * @deferdq: deferred receive queue
123  * @window: sliding window size for congestion handling
124  * @min_win: minimal send window to be used by link
125  * @ssthresh: slow start threshold for congestion handling
126  * @max_win: maximal send window to be used by link
127  * @cong_acks: congestion acks for congestion avoidance (FIXME)
128  * @checkpoint: seq number for congestion window size handling
129  * @reasm_tnlmsg: fragmentation/reassembly area for tunnel protocol message
130  * @last_gap: last gap ack blocks for bcast (FIXME)
131  * @last_ga: ptr to gap ack blocks
132  * @bc_rcvlink: the peer specific link used for broadcast reception
133  * @bc_sndlink: the namespace global link used for broadcast sending
134  * @nack_state: bcast nack state
135  * @bc_peer_is_up: peer has acked the bcast init msg
136  */
137 struct tipc_link {
138 	u32 addr;
139 	char name[TIPC_MAX_LINK_NAME];
140 	struct net *net;
141 
142 	/* Management and link supervision data */
143 	u16 peer_session;
144 	u16 session;
145 	u16 snd_nxt_state;
146 	u16 rcv_nxt_state;
147 	u32 peer_bearer_id;
148 	u32 bearer_id;
149 	u32 tolerance;
150 	u32 abort_limit;
151 	u32 state;
152 	u16 peer_caps;
153 	bool in_session;
154 	bool active;
155 	u32 silent_intv_cnt;
156 	char if_name[TIPC_MAX_IF_NAME];
157 	u32 priority;
158 	char net_plane;
159 	struct tipc_mon_state mon_state;
160 	u16 rst_cnt;
161 
162 	/* Failover/synch */
163 	u16 drop_point;
164 	struct sk_buff *failover_reasm_skb;
165 	struct sk_buff_head failover_deferdq;
166 
167 	/* Max packet negotiation */
168 	u16 mtu;
169 	u16 advertised_mtu;
170 
171 	/* Sending */
172 	struct sk_buff_head transmq;
173 	struct sk_buff_head backlogq;
174 	struct {
175 		u16 len;
176 		u16 limit;
177 		struct sk_buff *target_bskb;
178 	} backlog[5];
179 	u16 snd_nxt;
180 
181 	/* Reception */
182 	u16 rcv_nxt;
183 	u32 rcv_unacked;
184 	struct sk_buff_head deferdq;
185 	struct sk_buff_head *inputq;
186 	struct sk_buff_head *namedq;
187 
188 	/* Congestion handling */
189 	struct sk_buff_head wakeupq;
190 	u16 window;
191 	u16 min_win;
192 	u16 ssthresh;
193 	u16 max_win;
194 	u16 cong_acks;
195 	u16 checkpoint;
196 
197 	/* Fragmentation/reassembly */
198 	struct sk_buff *reasm_buf;
199 	struct sk_buff *reasm_tnlmsg;
200 
201 	/* Broadcast */
202 	u16 ackers;
203 	u16 acked;
204 	u16 last_gap;
205 	struct tipc_gap_ack_blks *last_ga;
206 	struct tipc_link *bc_rcvlink;
207 	struct tipc_link *bc_sndlink;
208 	u8 nack_state;
209 	bool bc_peer_is_up;
210 
211 	/* Statistics */
212 	struct tipc_stats stats;
213 };
214 
215 /*
216  * Error message prefixes
217  */
218 static const char *link_co_err = "Link tunneling error, ";
219 static const char *link_rst_msg = "Resetting link ";
220 
221 /* Send states for broadcast NACKs
222  */
223 enum {
224 	BC_NACK_SND_CONDITIONAL,
225 	BC_NACK_SND_UNCONDITIONAL,
226 	BC_NACK_SND_SUPPRESS,
227 };
228 
229 #define TIPC_BC_RETR_LIM  (jiffies + msecs_to_jiffies(10))
230 #define TIPC_UC_RETR_TIME (jiffies + msecs_to_jiffies(1))
231 
232 /* Link FSM states:
233  */
234 enum {
235 	LINK_ESTABLISHED     = 0xe,
236 	LINK_ESTABLISHING    = 0xe  << 4,
237 	LINK_RESET           = 0x1  << 8,
238 	LINK_RESETTING       = 0x2  << 12,
239 	LINK_PEER_RESET      = 0xd  << 16,
240 	LINK_FAILINGOVER     = 0xf  << 20,
241 	LINK_SYNCHING        = 0xc  << 24
242 };
243 
244 /* Link FSM state checking routines
245  */
246 static int link_is_up(struct tipc_link *l)
247 {
248 	return l->state & (LINK_ESTABLISHED | LINK_SYNCHING);
249 }
250 
251 static int tipc_link_proto_rcv(struct tipc_link *l, struct sk_buff *skb,
252 			       struct sk_buff_head *xmitq);
253 static void tipc_link_build_proto_msg(struct tipc_link *l, int mtyp, bool probe,
254 				      bool probe_reply, u16 rcvgap,
255 				      int tolerance, int priority,
256 				      struct sk_buff_head *xmitq);
257 static void link_print(struct tipc_link *l, const char *str);
258 static int tipc_link_build_nack_msg(struct tipc_link *l,
259 				    struct sk_buff_head *xmitq);
260 static void tipc_link_build_bc_init_msg(struct tipc_link *l,
261 					struct sk_buff_head *xmitq);
262 static u8 __tipc_build_gap_ack_blks(struct tipc_gap_ack_blks *ga,
263 				    struct tipc_link *l, u8 start_index);
264 static u16 tipc_build_gap_ack_blks(struct tipc_link *l, struct tipc_msg *hdr);
265 static int tipc_link_advance_transmq(struct tipc_link *l, struct tipc_link *r,
266 				     u16 acked, u16 gap,
267 				     struct tipc_gap_ack_blks *ga,
268 				     struct sk_buff_head *xmitq,
269 				     bool *retransmitted, int *rc);
270 static void tipc_link_update_cwin(struct tipc_link *l, int released,
271 				  bool retransmitted);
272 /*
273  *  Simple non-static link routines (i.e. referenced outside this file)
274  */
275 bool tipc_link_is_up(struct tipc_link *l)
276 {
277 	return link_is_up(l);
278 }
279 
280 bool tipc_link_peer_is_down(struct tipc_link *l)
281 {
282 	return l->state == LINK_PEER_RESET;
283 }
284 
285 bool tipc_link_is_reset(struct tipc_link *l)
286 {
287 	return l->state & (LINK_RESET | LINK_FAILINGOVER | LINK_ESTABLISHING);
288 }
289 
290 bool tipc_link_is_establishing(struct tipc_link *l)
291 {
292 	return l->state == LINK_ESTABLISHING;
293 }
294 
295 bool tipc_link_is_synching(struct tipc_link *l)
296 {
297 	return l->state == LINK_SYNCHING;
298 }
299 
300 bool tipc_link_is_failingover(struct tipc_link *l)
301 {
302 	return l->state == LINK_FAILINGOVER;
303 }
304 
305 bool tipc_link_is_blocked(struct tipc_link *l)
306 {
307 	return l->state & (LINK_RESETTING | LINK_PEER_RESET | LINK_FAILINGOVER);
308 }
309 
310 static bool link_is_bc_sndlink(struct tipc_link *l)
311 {
312 	return !l->bc_sndlink;
313 }
314 
315 static bool link_is_bc_rcvlink(struct tipc_link *l)
316 {
317 	return ((l->bc_rcvlink == l) && !link_is_bc_sndlink(l));
318 }
319 
320 void tipc_link_set_active(struct tipc_link *l, bool active)
321 {
322 	l->active = active;
323 }
324 
325 u32 tipc_link_id(struct tipc_link *l)
326 {
327 	return l->peer_bearer_id << 16 | l->bearer_id;
328 }
329 
330 int tipc_link_min_win(struct tipc_link *l)
331 {
332 	return l->min_win;
333 }
334 
335 int tipc_link_max_win(struct tipc_link *l)
336 {
337 	return l->max_win;
338 }
339 
340 int tipc_link_prio(struct tipc_link *l)
341 {
342 	return l->priority;
343 }
344 
345 unsigned long tipc_link_tolerance(struct tipc_link *l)
346 {
347 	return l->tolerance;
348 }
349 
350 struct sk_buff_head *tipc_link_inputq(struct tipc_link *l)
351 {
352 	return l->inputq;
353 }
354 
355 char tipc_link_plane(struct tipc_link *l)
356 {
357 	return l->net_plane;
358 }
359 
360 struct net *tipc_link_net(struct tipc_link *l)
361 {
362 	return l->net;
363 }
364 
365 void tipc_link_update_caps(struct tipc_link *l, u16 capabilities)
366 {
367 	l->peer_caps = capabilities;
368 }
369 
370 void tipc_link_add_bc_peer(struct tipc_link *snd_l,
371 			   struct tipc_link *uc_l,
372 			   struct sk_buff_head *xmitq)
373 {
374 	struct tipc_link *rcv_l = uc_l->bc_rcvlink;
375 
376 	snd_l->ackers++;
377 	rcv_l->acked = snd_l->snd_nxt - 1;
378 	snd_l->state = LINK_ESTABLISHED;
379 	tipc_link_build_bc_init_msg(uc_l, xmitq);
380 }
381 
382 void tipc_link_remove_bc_peer(struct tipc_link *snd_l,
383 			      struct tipc_link *rcv_l,
384 			      struct sk_buff_head *xmitq)
385 {
386 	u16 ack = snd_l->snd_nxt - 1;
387 
388 	snd_l->ackers--;
389 	rcv_l->bc_peer_is_up = true;
390 	rcv_l->state = LINK_ESTABLISHED;
391 	tipc_link_bc_ack_rcv(rcv_l, ack, 0, NULL, xmitq, NULL);
392 	trace_tipc_link_reset(rcv_l, TIPC_DUMP_ALL, "bclink removed!");
393 	tipc_link_reset(rcv_l);
394 	rcv_l->state = LINK_RESET;
395 	if (!snd_l->ackers) {
396 		trace_tipc_link_reset(snd_l, TIPC_DUMP_ALL, "zero ackers!");
397 		tipc_link_reset(snd_l);
398 		snd_l->state = LINK_RESET;
399 		__skb_queue_purge(xmitq);
400 	}
401 }
402 
403 int tipc_link_bc_peers(struct tipc_link *l)
404 {
405 	return l->ackers;
406 }
407 
408 static u16 link_bc_rcv_gap(struct tipc_link *l)
409 {
410 	struct sk_buff *skb = skb_peek(&l->deferdq);
411 	u16 gap = 0;
412 
413 	if (more(l->snd_nxt, l->rcv_nxt))
414 		gap = l->snd_nxt - l->rcv_nxt;
415 	if (skb)
416 		gap = buf_seqno(skb) - l->rcv_nxt;
417 	return gap;
418 }
419 
420 void tipc_link_set_mtu(struct tipc_link *l, int mtu)
421 {
422 	l->mtu = mtu;
423 }
424 
425 int tipc_link_mtu(struct tipc_link *l)
426 {
427 	return l->mtu;
428 }
429 
430 int tipc_link_mss(struct tipc_link *l)
431 {
432 #ifdef CONFIG_TIPC_CRYPTO
433 	return l->mtu - INT_H_SIZE - EMSG_OVERHEAD;
434 #else
435 	return l->mtu - INT_H_SIZE;
436 #endif
437 }
438 
439 u16 tipc_link_rcv_nxt(struct tipc_link *l)
440 {
441 	return l->rcv_nxt;
442 }
443 
444 u16 tipc_link_acked(struct tipc_link *l)
445 {
446 	return l->acked;
447 }
448 
449 char *tipc_link_name(struct tipc_link *l)
450 {
451 	return l->name;
452 }
453 
454 u32 tipc_link_state(struct tipc_link *l)
455 {
456 	return l->state;
457 }
458 
459 /**
460  * tipc_link_create - create a new link
461  * @net: pointer to associated network namespace
462  * @if_name: associated interface name
463  * @bearer_id: id (index) of associated bearer
464  * @tolerance: link tolerance to be used by link
465  * @net_plane: network plane (A,B,c..) this link belongs to
466  * @mtu: mtu to be advertised by link
467  * @priority: priority to be used by link
468  * @min_win: minimal send window to be used by link
469  * @max_win: maximal send window to be used by link
470  * @session: session to be used by link
471  * @peer: node id of peer node
472  * @peer_caps: bitmap describing peer node capabilities
473  * @bc_sndlink: the namespace global link used for broadcast sending
474  * @bc_rcvlink: the peer specific link used for broadcast reception
475  * @inputq: queue to put messages ready for delivery
476  * @namedq: queue to put binding table update messages ready for delivery
477  * @link: return value, pointer to put the created link
478  * @self: local unicast link id
479  * @peer_id: 128-bit ID of peer
480  *
481  * Return: true if link was created, otherwise false
482  */
483 bool tipc_link_create(struct net *net, char *if_name, int bearer_id,
484 		      int tolerance, char net_plane, u32 mtu, int priority,
485 		      u32 min_win, u32 max_win, u32 session, u32 self,
486 		      u32 peer, u8 *peer_id, u16 peer_caps,
487 		      struct tipc_link *bc_sndlink,
488 		      struct tipc_link *bc_rcvlink,
489 		      struct sk_buff_head *inputq,
490 		      struct sk_buff_head *namedq,
491 		      struct tipc_link **link)
492 {
493 	char peer_str[NODE_ID_STR_LEN] = {0,};
494 	char self_str[NODE_ID_STR_LEN] = {0,};
495 	struct tipc_link *l;
496 
497 	l = kzalloc(sizeof(*l), GFP_ATOMIC);
498 	if (!l)
499 		return false;
500 	*link = l;
501 	l->session = session;
502 
503 	/* Set link name for unicast links only */
504 	if (peer_id) {
505 		tipc_nodeid2string(self_str, tipc_own_id(net));
506 		if (strlen(self_str) > 16)
507 			sprintf(self_str, "%x", self);
508 		tipc_nodeid2string(peer_str, peer_id);
509 		if (strlen(peer_str) > 16)
510 			sprintf(peer_str, "%x", peer);
511 	}
512 	/* Peer i/f name will be completed by reset/activate message */
513 	snprintf(l->name, sizeof(l->name), "%s:%s-%s:unknown",
514 		 self_str, if_name, peer_str);
515 
516 	strcpy(l->if_name, if_name);
517 	l->addr = peer;
518 	l->peer_caps = peer_caps;
519 	l->net = net;
520 	l->in_session = false;
521 	l->bearer_id = bearer_id;
522 	l->tolerance = tolerance;
523 	if (bc_rcvlink)
524 		bc_rcvlink->tolerance = tolerance;
525 	l->net_plane = net_plane;
526 	l->advertised_mtu = mtu;
527 	l->mtu = mtu;
528 	l->priority = priority;
529 	tipc_link_set_queue_limits(l, min_win, max_win);
530 	l->ackers = 1;
531 	l->bc_sndlink = bc_sndlink;
532 	l->bc_rcvlink = bc_rcvlink;
533 	l->inputq = inputq;
534 	l->namedq = namedq;
535 	l->state = LINK_RESETTING;
536 	__skb_queue_head_init(&l->transmq);
537 	__skb_queue_head_init(&l->backlogq);
538 	__skb_queue_head_init(&l->deferdq);
539 	__skb_queue_head_init(&l->failover_deferdq);
540 	skb_queue_head_init(&l->wakeupq);
541 	skb_queue_head_init(l->inputq);
542 	return true;
543 }
544 
545 /**
546  * tipc_link_bc_create - create new link to be used for broadcast
547  * @net: pointer to associated network namespace
548  * @mtu: mtu to be used initially if no peers
549  * @min_win: minimal send window to be used by link
550  * @max_win: maximal send window to be used by link
551  * @inputq: queue to put messages ready for delivery
552  * @namedq: queue to put binding table update messages ready for delivery
553  * @link: return value, pointer to put the created link
554  * @ownnode: identity of own node
555  * @peer: node id of peer node
556  * @peer_id: 128-bit ID of peer
557  * @peer_caps: bitmap describing peer node capabilities
558  * @bc_sndlink: the namespace global link used for broadcast sending
559  *
560  * Return: true if link was created, otherwise false
561  */
562 bool tipc_link_bc_create(struct net *net, u32 ownnode, u32 peer, u8 *peer_id,
563 			 int mtu, u32 min_win, u32 max_win, u16 peer_caps,
564 			 struct sk_buff_head *inputq,
565 			 struct sk_buff_head *namedq,
566 			 struct tipc_link *bc_sndlink,
567 			 struct tipc_link **link)
568 {
569 	struct tipc_link *l;
570 
571 	if (!tipc_link_create(net, "", MAX_BEARERS, 0, 'Z', mtu, 0, min_win,
572 			      max_win, 0, ownnode, peer, NULL, peer_caps,
573 			      bc_sndlink, NULL, inputq, namedq, link))
574 		return false;
575 
576 	l = *link;
577 	if (peer_id) {
578 		char peer_str[NODE_ID_STR_LEN] = {0,};
579 
580 		tipc_nodeid2string(peer_str, peer_id);
581 		if (strlen(peer_str) > 16)
582 			sprintf(peer_str, "%x", peer);
583 		/* Broadcast receiver link name: "broadcast-link:<peer>" */
584 		snprintf(l->name, sizeof(l->name), "%s:%s", tipc_bclink_name,
585 			 peer_str);
586 	} else {
587 		strcpy(l->name, tipc_bclink_name);
588 	}
589 	trace_tipc_link_reset(l, TIPC_DUMP_ALL, "bclink created!");
590 	tipc_link_reset(l);
591 	l->state = LINK_RESET;
592 	l->ackers = 0;
593 	l->bc_rcvlink = l;
594 
595 	/* Broadcast send link is always up */
596 	if (link_is_bc_sndlink(l))
597 		l->state = LINK_ESTABLISHED;
598 
599 	/* Disable replicast if even a single peer doesn't support it */
600 	if (link_is_bc_rcvlink(l) && !(peer_caps & TIPC_BCAST_RCAST))
601 		tipc_bcast_toggle_rcast(net, false);
602 
603 	return true;
604 }
605 
606 /**
607  * tipc_link_fsm_evt - link finite state machine
608  * @l: pointer to link
609  * @evt: state machine event to be processed
610  */
611 int tipc_link_fsm_evt(struct tipc_link *l, int evt)
612 {
613 	int rc = 0;
614 	int old_state = l->state;
615 
616 	switch (l->state) {
617 	case LINK_RESETTING:
618 		switch (evt) {
619 		case LINK_PEER_RESET_EVT:
620 			l->state = LINK_PEER_RESET;
621 			break;
622 		case LINK_RESET_EVT:
623 			l->state = LINK_RESET;
624 			break;
625 		case LINK_FAILURE_EVT:
626 		case LINK_FAILOVER_BEGIN_EVT:
627 		case LINK_ESTABLISH_EVT:
628 		case LINK_FAILOVER_END_EVT:
629 		case LINK_SYNCH_BEGIN_EVT:
630 		case LINK_SYNCH_END_EVT:
631 		default:
632 			goto illegal_evt;
633 		}
634 		break;
635 	case LINK_RESET:
636 		switch (evt) {
637 		case LINK_PEER_RESET_EVT:
638 			l->state = LINK_ESTABLISHING;
639 			break;
640 		case LINK_FAILOVER_BEGIN_EVT:
641 			l->state = LINK_FAILINGOVER;
642 			break;
643 		case LINK_FAILURE_EVT:
644 		case LINK_RESET_EVT:
645 		case LINK_ESTABLISH_EVT:
646 		case LINK_FAILOVER_END_EVT:
647 			break;
648 		case LINK_SYNCH_BEGIN_EVT:
649 		case LINK_SYNCH_END_EVT:
650 		default:
651 			goto illegal_evt;
652 		}
653 		break;
654 	case LINK_PEER_RESET:
655 		switch (evt) {
656 		case LINK_RESET_EVT:
657 			l->state = LINK_ESTABLISHING;
658 			break;
659 		case LINK_PEER_RESET_EVT:
660 		case LINK_ESTABLISH_EVT:
661 		case LINK_FAILURE_EVT:
662 			break;
663 		case LINK_SYNCH_BEGIN_EVT:
664 		case LINK_SYNCH_END_EVT:
665 		case LINK_FAILOVER_BEGIN_EVT:
666 		case LINK_FAILOVER_END_EVT:
667 		default:
668 			goto illegal_evt;
669 		}
670 		break;
671 	case LINK_FAILINGOVER:
672 		switch (evt) {
673 		case LINK_FAILOVER_END_EVT:
674 			l->state = LINK_RESET;
675 			break;
676 		case LINK_PEER_RESET_EVT:
677 		case LINK_RESET_EVT:
678 		case LINK_ESTABLISH_EVT:
679 		case LINK_FAILURE_EVT:
680 			break;
681 		case LINK_FAILOVER_BEGIN_EVT:
682 		case LINK_SYNCH_BEGIN_EVT:
683 		case LINK_SYNCH_END_EVT:
684 		default:
685 			goto illegal_evt;
686 		}
687 		break;
688 	case LINK_ESTABLISHING:
689 		switch (evt) {
690 		case LINK_ESTABLISH_EVT:
691 			l->state = LINK_ESTABLISHED;
692 			break;
693 		case LINK_FAILOVER_BEGIN_EVT:
694 			l->state = LINK_FAILINGOVER;
695 			break;
696 		case LINK_RESET_EVT:
697 			l->state = LINK_RESET;
698 			break;
699 		case LINK_FAILURE_EVT:
700 		case LINK_PEER_RESET_EVT:
701 		case LINK_SYNCH_BEGIN_EVT:
702 		case LINK_FAILOVER_END_EVT:
703 			break;
704 		case LINK_SYNCH_END_EVT:
705 		default:
706 			goto illegal_evt;
707 		}
708 		break;
709 	case LINK_ESTABLISHED:
710 		switch (evt) {
711 		case LINK_PEER_RESET_EVT:
712 			l->state = LINK_PEER_RESET;
713 			rc |= TIPC_LINK_DOWN_EVT;
714 			break;
715 		case LINK_FAILURE_EVT:
716 			l->state = LINK_RESETTING;
717 			rc |= TIPC_LINK_DOWN_EVT;
718 			break;
719 		case LINK_RESET_EVT:
720 			l->state = LINK_RESET;
721 			break;
722 		case LINK_ESTABLISH_EVT:
723 		case LINK_SYNCH_END_EVT:
724 			break;
725 		case LINK_SYNCH_BEGIN_EVT:
726 			l->state = LINK_SYNCHING;
727 			break;
728 		case LINK_FAILOVER_BEGIN_EVT:
729 		case LINK_FAILOVER_END_EVT:
730 		default:
731 			goto illegal_evt;
732 		}
733 		break;
734 	case LINK_SYNCHING:
735 		switch (evt) {
736 		case LINK_PEER_RESET_EVT:
737 			l->state = LINK_PEER_RESET;
738 			rc |= TIPC_LINK_DOWN_EVT;
739 			break;
740 		case LINK_FAILURE_EVT:
741 			l->state = LINK_RESETTING;
742 			rc |= TIPC_LINK_DOWN_EVT;
743 			break;
744 		case LINK_RESET_EVT:
745 			l->state = LINK_RESET;
746 			break;
747 		case LINK_ESTABLISH_EVT:
748 		case LINK_SYNCH_BEGIN_EVT:
749 			break;
750 		case LINK_SYNCH_END_EVT:
751 			l->state = LINK_ESTABLISHED;
752 			break;
753 		case LINK_FAILOVER_BEGIN_EVT:
754 		case LINK_FAILOVER_END_EVT:
755 		default:
756 			goto illegal_evt;
757 		}
758 		break;
759 	default:
760 		pr_err("Unknown FSM state %x in %s\n", l->state, l->name);
761 	}
762 	trace_tipc_link_fsm(l->name, old_state, l->state, evt);
763 	return rc;
764 illegal_evt:
765 	pr_err("Illegal FSM event %x in state %x on link %s\n",
766 	       evt, l->state, l->name);
767 	trace_tipc_link_fsm(l->name, old_state, l->state, evt);
768 	return rc;
769 }
770 
771 /* link_profile_stats - update statistical profiling of traffic
772  */
773 static void link_profile_stats(struct tipc_link *l)
774 {
775 	struct sk_buff *skb;
776 	struct tipc_msg *msg;
777 	int length;
778 
779 	/* Update counters used in statistical profiling of send traffic */
780 	l->stats.accu_queue_sz += skb_queue_len(&l->transmq);
781 	l->stats.queue_sz_counts++;
782 
783 	skb = skb_peek(&l->transmq);
784 	if (!skb)
785 		return;
786 	msg = buf_msg(skb);
787 	length = msg_size(msg);
788 
789 	if (msg_user(msg) == MSG_FRAGMENTER) {
790 		if (msg_type(msg) != FIRST_FRAGMENT)
791 			return;
792 		length = msg_size(msg_inner_hdr(msg));
793 	}
794 	l->stats.msg_lengths_total += length;
795 	l->stats.msg_length_counts++;
796 	if (length <= 64)
797 		l->stats.msg_length_profile[0]++;
798 	else if (length <= 256)
799 		l->stats.msg_length_profile[1]++;
800 	else if (length <= 1024)
801 		l->stats.msg_length_profile[2]++;
802 	else if (length <= 4096)
803 		l->stats.msg_length_profile[3]++;
804 	else if (length <= 16384)
805 		l->stats.msg_length_profile[4]++;
806 	else if (length <= 32768)
807 		l->stats.msg_length_profile[5]++;
808 	else
809 		l->stats.msg_length_profile[6]++;
810 }
811 
812 /**
813  * tipc_link_too_silent - check if link is "too silent"
814  * @l: tipc link to be checked
815  *
816  * Return: true if the link 'silent_intv_cnt' is about to reach the
817  * 'abort_limit' value, otherwise false
818  */
819 bool tipc_link_too_silent(struct tipc_link *l)
820 {
821 	return (l->silent_intv_cnt + 2 > l->abort_limit);
822 }
823 
824 /* tipc_link_timeout - perform periodic task as instructed from node timeout
825  */
826 int tipc_link_timeout(struct tipc_link *l, struct sk_buff_head *xmitq)
827 {
828 	int mtyp = 0;
829 	int rc = 0;
830 	bool state = false;
831 	bool probe = false;
832 	bool setup = false;
833 	u16 bc_snt = l->bc_sndlink->snd_nxt - 1;
834 	u16 bc_acked = l->bc_rcvlink->acked;
835 	struct tipc_mon_state *mstate = &l->mon_state;
836 
837 	trace_tipc_link_timeout(l, TIPC_DUMP_NONE, " ");
838 	trace_tipc_link_too_silent(l, TIPC_DUMP_ALL, " ");
839 	switch (l->state) {
840 	case LINK_ESTABLISHED:
841 	case LINK_SYNCHING:
842 		mtyp = STATE_MSG;
843 		link_profile_stats(l);
844 		tipc_mon_get_state(l->net, l->addr, mstate, l->bearer_id);
845 		if (mstate->reset || (l->silent_intv_cnt > l->abort_limit))
846 			return tipc_link_fsm_evt(l, LINK_FAILURE_EVT);
847 		state = bc_acked != bc_snt;
848 		state |= l->bc_rcvlink->rcv_unacked;
849 		state |= l->rcv_unacked;
850 		state |= !skb_queue_empty(&l->transmq);
851 		probe = mstate->probing;
852 		probe |= l->silent_intv_cnt;
853 		if (probe || mstate->monitoring)
854 			l->silent_intv_cnt++;
855 		probe |= !skb_queue_empty(&l->deferdq);
856 		if (l->snd_nxt == l->checkpoint) {
857 			tipc_link_update_cwin(l, 0, 0);
858 			probe = true;
859 		}
860 		l->checkpoint = l->snd_nxt;
861 		break;
862 	case LINK_RESET:
863 		setup = l->rst_cnt++ <= 4;
864 		setup |= !(l->rst_cnt % 16);
865 		mtyp = RESET_MSG;
866 		break;
867 	case LINK_ESTABLISHING:
868 		setup = true;
869 		mtyp = ACTIVATE_MSG;
870 		break;
871 	case LINK_PEER_RESET:
872 	case LINK_RESETTING:
873 	case LINK_FAILINGOVER:
874 		break;
875 	default:
876 		break;
877 	}
878 
879 	if (state || probe || setup)
880 		tipc_link_build_proto_msg(l, mtyp, probe, 0, 0, 0, 0, xmitq);
881 
882 	return rc;
883 }
884 
885 /**
886  * link_schedule_user - schedule a message sender for wakeup after congestion
887  * @l: congested link
888  * @hdr: header of message that is being sent
889  * Create pseudo msg to send back to user when congestion abates
890  */
891 static int link_schedule_user(struct tipc_link *l, struct tipc_msg *hdr)
892 {
893 	u32 dnode = tipc_own_addr(l->net);
894 	u32 dport = msg_origport(hdr);
895 	struct sk_buff *skb;
896 
897 	/* Create and schedule wakeup pseudo message */
898 	skb = tipc_msg_create(SOCK_WAKEUP, 0, INT_H_SIZE, 0,
899 			      dnode, l->addr, dport, 0, 0);
900 	if (!skb)
901 		return -ENOBUFS;
902 	msg_set_dest_droppable(buf_msg(skb), true);
903 	TIPC_SKB_CB(skb)->chain_imp = msg_importance(hdr);
904 	skb_queue_tail(&l->wakeupq, skb);
905 	l->stats.link_congs++;
906 	trace_tipc_link_conges(l, TIPC_DUMP_ALL, "wakeup scheduled!");
907 	return -ELINKCONG;
908 }
909 
910 /**
911  * link_prepare_wakeup - prepare users for wakeup after congestion
912  * @l: congested link
913  * Wake up a number of waiting users, as permitted by available space
914  * in the send queue
915  */
916 static void link_prepare_wakeup(struct tipc_link *l)
917 {
918 	struct sk_buff_head *wakeupq = &l->wakeupq;
919 	struct sk_buff_head *inputq = l->inputq;
920 	struct sk_buff *skb, *tmp;
921 	struct sk_buff_head tmpq;
922 	int avail[5] = {0,};
923 	int imp = 0;
924 
925 	__skb_queue_head_init(&tmpq);
926 
927 	for (; imp <= TIPC_SYSTEM_IMPORTANCE; imp++)
928 		avail[imp] = l->backlog[imp].limit - l->backlog[imp].len;
929 
930 	skb_queue_walk_safe(wakeupq, skb, tmp) {
931 		imp = TIPC_SKB_CB(skb)->chain_imp;
932 		if (avail[imp] <= 0)
933 			continue;
934 		avail[imp]--;
935 		__skb_unlink(skb, wakeupq);
936 		__skb_queue_tail(&tmpq, skb);
937 	}
938 
939 	spin_lock_bh(&inputq->lock);
940 	skb_queue_splice_tail(&tmpq, inputq);
941 	spin_unlock_bh(&inputq->lock);
942 
943 }
944 
945 /**
946  * tipc_link_set_skb_retransmit_time - set the time at which retransmission of
947  *                                     the given skb should be next attempted
948  * @skb: skb to set a future retransmission time for
949  * @l: link the skb will be transmitted on
950  */
951 static void tipc_link_set_skb_retransmit_time(struct sk_buff *skb,
952 					      struct tipc_link *l)
953 {
954 	if (link_is_bc_sndlink(l))
955 		TIPC_SKB_CB(skb)->nxt_retr = TIPC_BC_RETR_LIM;
956 	else
957 		TIPC_SKB_CB(skb)->nxt_retr = TIPC_UC_RETR_TIME;
958 }
959 
960 void tipc_link_reset(struct tipc_link *l)
961 {
962 	struct sk_buff_head list;
963 	u32 imp;
964 
965 	__skb_queue_head_init(&list);
966 
967 	l->in_session = false;
968 	/* Force re-synch of peer session number before establishing */
969 	l->peer_session--;
970 	l->session++;
971 	l->mtu = l->advertised_mtu;
972 
973 	spin_lock_bh(&l->wakeupq.lock);
974 	skb_queue_splice_init(&l->wakeupq, &list);
975 	spin_unlock_bh(&l->wakeupq.lock);
976 
977 	spin_lock_bh(&l->inputq->lock);
978 	skb_queue_splice_init(&list, l->inputq);
979 	spin_unlock_bh(&l->inputq->lock);
980 
981 	__skb_queue_purge(&l->transmq);
982 	__skb_queue_purge(&l->deferdq);
983 	__skb_queue_purge(&l->backlogq);
984 	__skb_queue_purge(&l->failover_deferdq);
985 	for (imp = 0; imp <= TIPC_SYSTEM_IMPORTANCE; imp++) {
986 		l->backlog[imp].len = 0;
987 		l->backlog[imp].target_bskb = NULL;
988 	}
989 	kfree_skb(l->reasm_buf);
990 	kfree_skb(l->reasm_tnlmsg);
991 	kfree_skb(l->failover_reasm_skb);
992 	l->reasm_buf = NULL;
993 	l->reasm_tnlmsg = NULL;
994 	l->failover_reasm_skb = NULL;
995 	l->rcv_unacked = 0;
996 	l->snd_nxt = 1;
997 	l->rcv_nxt = 1;
998 	l->snd_nxt_state = 1;
999 	l->rcv_nxt_state = 1;
1000 	l->acked = 0;
1001 	l->last_gap = 0;
1002 	kfree(l->last_ga);
1003 	l->last_ga = NULL;
1004 	l->silent_intv_cnt = 0;
1005 	l->rst_cnt = 0;
1006 	l->bc_peer_is_up = false;
1007 	memset(&l->mon_state, 0, sizeof(l->mon_state));
1008 	tipc_link_reset_stats(l);
1009 }
1010 
1011 /**
1012  * tipc_link_xmit(): enqueue buffer list according to queue situation
1013  * @l: link to use
1014  * @list: chain of buffers containing message
1015  * @xmitq: returned list of packets to be sent by caller
1016  *
1017  * Consumes the buffer chain.
1018  * Messages at TIPC_SYSTEM_IMPORTANCE are always accepted
1019  * Return: 0 if success, or errno: -ELINKCONG, -EMSGSIZE or -ENOBUFS
1020  */
1021 int tipc_link_xmit(struct tipc_link *l, struct sk_buff_head *list,
1022 		   struct sk_buff_head *xmitq)
1023 {
1024 	struct sk_buff_head *backlogq = &l->backlogq;
1025 	struct sk_buff_head *transmq = &l->transmq;
1026 	struct sk_buff *skb, *_skb;
1027 	u16 bc_ack = l->bc_rcvlink->rcv_nxt - 1;
1028 	u16 ack = l->rcv_nxt - 1;
1029 	u16 seqno = l->snd_nxt;
1030 	int pkt_cnt = skb_queue_len(list);
1031 	unsigned int mss = tipc_link_mss(l);
1032 	unsigned int cwin = l->window;
1033 	unsigned int mtu = l->mtu;
1034 	struct tipc_msg *hdr;
1035 	bool new_bundle;
1036 	int rc = 0;
1037 	int imp;
1038 
1039 	if (pkt_cnt <= 0)
1040 		return 0;
1041 
1042 	hdr = buf_msg(skb_peek(list));
1043 	if (unlikely(msg_size(hdr) > mtu)) {
1044 		pr_warn("Too large msg, purging xmit list %d %d %d %d %d!\n",
1045 			skb_queue_len(list), msg_user(hdr),
1046 			msg_type(hdr), msg_size(hdr), mtu);
1047 		__skb_queue_purge(list);
1048 		return -EMSGSIZE;
1049 	}
1050 
1051 	imp = msg_importance(hdr);
1052 	/* Allow oversubscription of one data msg per source at congestion */
1053 	if (unlikely(l->backlog[imp].len >= l->backlog[imp].limit)) {
1054 		if (imp == TIPC_SYSTEM_IMPORTANCE) {
1055 			pr_warn("%s<%s>, link overflow", link_rst_msg, l->name);
1056 			return -ENOBUFS;
1057 		}
1058 		rc = link_schedule_user(l, hdr);
1059 	}
1060 
1061 	if (pkt_cnt > 1) {
1062 		l->stats.sent_fragmented++;
1063 		l->stats.sent_fragments += pkt_cnt;
1064 	}
1065 
1066 	/* Prepare each packet for sending, and add to relevant queue: */
1067 	while ((skb = __skb_dequeue(list))) {
1068 		if (likely(skb_queue_len(transmq) < cwin)) {
1069 			hdr = buf_msg(skb);
1070 			msg_set_seqno(hdr, seqno);
1071 			msg_set_ack(hdr, ack);
1072 			msg_set_bcast_ack(hdr, bc_ack);
1073 			_skb = skb_clone(skb, GFP_ATOMIC);
1074 			if (!_skb) {
1075 				kfree_skb(skb);
1076 				__skb_queue_purge(list);
1077 				return -ENOBUFS;
1078 			}
1079 			__skb_queue_tail(transmq, skb);
1080 			tipc_link_set_skb_retransmit_time(skb, l);
1081 			__skb_queue_tail(xmitq, _skb);
1082 			TIPC_SKB_CB(skb)->ackers = l->ackers;
1083 			l->rcv_unacked = 0;
1084 			l->stats.sent_pkts++;
1085 			seqno++;
1086 			continue;
1087 		}
1088 		if (tipc_msg_try_bundle(l->backlog[imp].target_bskb, &skb,
1089 					mss, l->addr, &new_bundle)) {
1090 			if (skb) {
1091 				/* Keep a ref. to the skb for next try */
1092 				l->backlog[imp].target_bskb = skb;
1093 				l->backlog[imp].len++;
1094 				__skb_queue_tail(backlogq, skb);
1095 			} else {
1096 				if (new_bundle) {
1097 					l->stats.sent_bundles++;
1098 					l->stats.sent_bundled++;
1099 				}
1100 				l->stats.sent_bundled++;
1101 			}
1102 			continue;
1103 		}
1104 		l->backlog[imp].target_bskb = NULL;
1105 		l->backlog[imp].len += (1 + skb_queue_len(list));
1106 		__skb_queue_tail(backlogq, skb);
1107 		skb_queue_splice_tail_init(list, backlogq);
1108 	}
1109 	l->snd_nxt = seqno;
1110 	return rc;
1111 }
1112 
1113 static void tipc_link_update_cwin(struct tipc_link *l, int released,
1114 				  bool retransmitted)
1115 {
1116 	int bklog_len = skb_queue_len(&l->backlogq);
1117 	struct sk_buff_head *txq = &l->transmq;
1118 	int txq_len = skb_queue_len(txq);
1119 	u16 cwin = l->window;
1120 
1121 	/* Enter fast recovery */
1122 	if (unlikely(retransmitted)) {
1123 		l->ssthresh = max_t(u16, l->window / 2, 300);
1124 		l->window = min_t(u16, l->ssthresh, l->window);
1125 		return;
1126 	}
1127 	/* Enter slow start */
1128 	if (unlikely(!released)) {
1129 		l->ssthresh = max_t(u16, l->window / 2, 300);
1130 		l->window = l->min_win;
1131 		return;
1132 	}
1133 	/* Don't increase window if no pressure on the transmit queue */
1134 	if (txq_len + bklog_len < cwin)
1135 		return;
1136 
1137 	/* Don't increase window if there are holes the transmit queue */
1138 	if (txq_len && l->snd_nxt - buf_seqno(skb_peek(txq)) != txq_len)
1139 		return;
1140 
1141 	l->cong_acks += released;
1142 
1143 	/* Slow start  */
1144 	if (cwin <= l->ssthresh) {
1145 		l->window = min_t(u16, cwin + released, l->max_win);
1146 		return;
1147 	}
1148 	/* Congestion avoidance */
1149 	if (l->cong_acks < cwin)
1150 		return;
1151 	l->window = min_t(u16, ++cwin, l->max_win);
1152 	l->cong_acks = 0;
1153 }
1154 
1155 static void tipc_link_advance_backlog(struct tipc_link *l,
1156 				      struct sk_buff_head *xmitq)
1157 {
1158 	u16 bc_ack = l->bc_rcvlink->rcv_nxt - 1;
1159 	struct sk_buff_head *txq = &l->transmq;
1160 	struct sk_buff *skb, *_skb;
1161 	u16 ack = l->rcv_nxt - 1;
1162 	u16 seqno = l->snd_nxt;
1163 	struct tipc_msg *hdr;
1164 	u16 cwin = l->window;
1165 	u32 imp;
1166 
1167 	while (skb_queue_len(txq) < cwin) {
1168 		skb = skb_peek(&l->backlogq);
1169 		if (!skb)
1170 			break;
1171 		_skb = skb_clone(skb, GFP_ATOMIC);
1172 		if (!_skb)
1173 			break;
1174 		__skb_dequeue(&l->backlogq);
1175 		hdr = buf_msg(skb);
1176 		imp = msg_importance(hdr);
1177 		l->backlog[imp].len--;
1178 		if (unlikely(skb == l->backlog[imp].target_bskb))
1179 			l->backlog[imp].target_bskb = NULL;
1180 		__skb_queue_tail(&l->transmq, skb);
1181 		tipc_link_set_skb_retransmit_time(skb, l);
1182 
1183 		__skb_queue_tail(xmitq, _skb);
1184 		TIPC_SKB_CB(skb)->ackers = l->ackers;
1185 		msg_set_seqno(hdr, seqno);
1186 		msg_set_ack(hdr, ack);
1187 		msg_set_bcast_ack(hdr, bc_ack);
1188 		l->rcv_unacked = 0;
1189 		l->stats.sent_pkts++;
1190 		seqno++;
1191 	}
1192 	l->snd_nxt = seqno;
1193 }
1194 
1195 /**
1196  * link_retransmit_failure() - Detect repeated retransmit failures
1197  * @l: tipc link sender
1198  * @r: tipc link receiver (= l in case of unicast)
1199  * @rc: returned code
1200  *
1201  * Return: true if the repeated retransmit failures happens, otherwise
1202  * false
1203  */
1204 static bool link_retransmit_failure(struct tipc_link *l, struct tipc_link *r,
1205 				    int *rc)
1206 {
1207 	struct sk_buff *skb = skb_peek(&l->transmq);
1208 	struct tipc_msg *hdr;
1209 
1210 	if (!skb)
1211 		return false;
1212 
1213 	if (!TIPC_SKB_CB(skb)->retr_cnt)
1214 		return false;
1215 
1216 	if (!time_after(jiffies, TIPC_SKB_CB(skb)->retr_stamp +
1217 			msecs_to_jiffies(r->tolerance * 10)))
1218 		return false;
1219 
1220 	hdr = buf_msg(skb);
1221 	if (link_is_bc_sndlink(l) && !less(r->acked, msg_seqno(hdr)))
1222 		return false;
1223 
1224 	pr_warn("Retransmission failure on link <%s>\n", l->name);
1225 	link_print(l, "State of link ");
1226 	pr_info("Failed msg: usr %u, typ %u, len %u, err %u\n",
1227 		msg_user(hdr), msg_type(hdr), msg_size(hdr), msg_errcode(hdr));
1228 	pr_info("sqno %u, prev: %x, dest: %x\n",
1229 		msg_seqno(hdr), msg_prevnode(hdr), msg_destnode(hdr));
1230 	pr_info("retr_stamp %d, retr_cnt %d\n",
1231 		jiffies_to_msecs(TIPC_SKB_CB(skb)->retr_stamp),
1232 		TIPC_SKB_CB(skb)->retr_cnt);
1233 
1234 	trace_tipc_list_dump(&l->transmq, true, "retrans failure!");
1235 	trace_tipc_link_dump(l, TIPC_DUMP_NONE, "retrans failure!");
1236 	trace_tipc_link_dump(r, TIPC_DUMP_NONE, "retrans failure!");
1237 
1238 	if (link_is_bc_sndlink(l)) {
1239 		r->state = LINK_RESET;
1240 		*rc |= TIPC_LINK_DOWN_EVT;
1241 	} else {
1242 		*rc |= tipc_link_fsm_evt(l, LINK_FAILURE_EVT);
1243 	}
1244 
1245 	return true;
1246 }
1247 
1248 /* tipc_data_input - deliver data and name distr msgs to upper layer
1249  *
1250  * Consumes buffer if message is of right type
1251  * Node lock must be held
1252  */
1253 static bool tipc_data_input(struct tipc_link *l, struct sk_buff *skb,
1254 			    struct sk_buff_head *inputq)
1255 {
1256 	struct sk_buff_head *mc_inputq = l->bc_rcvlink->inputq;
1257 	struct tipc_msg *hdr = buf_msg(skb);
1258 
1259 	switch (msg_user(hdr)) {
1260 	case TIPC_LOW_IMPORTANCE:
1261 	case TIPC_MEDIUM_IMPORTANCE:
1262 	case TIPC_HIGH_IMPORTANCE:
1263 	case TIPC_CRITICAL_IMPORTANCE:
1264 		if (unlikely(msg_in_group(hdr) || msg_mcast(hdr))) {
1265 			skb_queue_tail(mc_inputq, skb);
1266 			return true;
1267 		}
1268 		fallthrough;
1269 	case CONN_MANAGER:
1270 		skb_queue_tail(inputq, skb);
1271 		return true;
1272 	case GROUP_PROTOCOL:
1273 		skb_queue_tail(mc_inputq, skb);
1274 		return true;
1275 	case NAME_DISTRIBUTOR:
1276 		l->bc_rcvlink->state = LINK_ESTABLISHED;
1277 		skb_queue_tail(l->namedq, skb);
1278 		return true;
1279 	case MSG_BUNDLER:
1280 	case TUNNEL_PROTOCOL:
1281 	case MSG_FRAGMENTER:
1282 	case BCAST_PROTOCOL:
1283 		return false;
1284 #ifdef CONFIG_TIPC_CRYPTO
1285 	case MSG_CRYPTO:
1286 		if (sysctl_tipc_key_exchange_enabled &&
1287 		    TIPC_SKB_CB(skb)->decrypted) {
1288 			tipc_crypto_msg_rcv(l->net, skb);
1289 			return true;
1290 		}
1291 		fallthrough;
1292 #endif
1293 	default:
1294 		pr_warn("Dropping received illegal msg type\n");
1295 		kfree_skb(skb);
1296 		return true;
1297 	}
1298 }
1299 
1300 /* tipc_link_input - process packet that has passed link protocol check
1301  *
1302  * Consumes buffer
1303  */
1304 static int tipc_link_input(struct tipc_link *l, struct sk_buff *skb,
1305 			   struct sk_buff_head *inputq,
1306 			   struct sk_buff **reasm_skb)
1307 {
1308 	struct tipc_msg *hdr = buf_msg(skb);
1309 	struct sk_buff *iskb;
1310 	struct sk_buff_head tmpq;
1311 	int usr = msg_user(hdr);
1312 	int pos = 0;
1313 
1314 	if (usr == MSG_BUNDLER) {
1315 		skb_queue_head_init(&tmpq);
1316 		l->stats.recv_bundles++;
1317 		l->stats.recv_bundled += msg_msgcnt(hdr);
1318 		while (tipc_msg_extract(skb, &iskb, &pos))
1319 			tipc_data_input(l, iskb, &tmpq);
1320 		tipc_skb_queue_splice_tail(&tmpq, inputq);
1321 		return 0;
1322 	} else if (usr == MSG_FRAGMENTER) {
1323 		l->stats.recv_fragments++;
1324 		if (tipc_buf_append(reasm_skb, &skb)) {
1325 			l->stats.recv_fragmented++;
1326 			tipc_data_input(l, skb, inputq);
1327 		} else if (!*reasm_skb && !link_is_bc_rcvlink(l)) {
1328 			pr_warn_ratelimited("Unable to build fragment list\n");
1329 			return tipc_link_fsm_evt(l, LINK_FAILURE_EVT);
1330 		}
1331 		return 0;
1332 	} else if (usr == BCAST_PROTOCOL) {
1333 		tipc_bcast_lock(l->net);
1334 		tipc_link_bc_init_rcv(l->bc_rcvlink, hdr);
1335 		tipc_bcast_unlock(l->net);
1336 	}
1337 
1338 	kfree_skb(skb);
1339 	return 0;
1340 }
1341 
1342 /* tipc_link_tnl_rcv() - receive TUNNEL_PROTOCOL message, drop or process the
1343  *			 inner message along with the ones in the old link's
1344  *			 deferdq
1345  * @l: tunnel link
1346  * @skb: TUNNEL_PROTOCOL message
1347  * @inputq: queue to put messages ready for delivery
1348  */
1349 static int tipc_link_tnl_rcv(struct tipc_link *l, struct sk_buff *skb,
1350 			     struct sk_buff_head *inputq)
1351 {
1352 	struct sk_buff **reasm_skb = &l->failover_reasm_skb;
1353 	struct sk_buff **reasm_tnlmsg = &l->reasm_tnlmsg;
1354 	struct sk_buff_head *fdefq = &l->failover_deferdq;
1355 	struct tipc_msg *hdr = buf_msg(skb);
1356 	struct sk_buff *iskb;
1357 	int ipos = 0;
1358 	int rc = 0;
1359 	u16 seqno;
1360 
1361 	if (msg_type(hdr) == SYNCH_MSG) {
1362 		kfree_skb(skb);
1363 		return 0;
1364 	}
1365 
1366 	/* Not a fragment? */
1367 	if (likely(!msg_nof_fragms(hdr))) {
1368 		if (unlikely(!tipc_msg_extract(skb, &iskb, &ipos))) {
1369 			pr_warn_ratelimited("Unable to extract msg, defq: %d\n",
1370 					    skb_queue_len(fdefq));
1371 			return 0;
1372 		}
1373 		kfree_skb(skb);
1374 	} else {
1375 		/* Set fragment type for buf_append */
1376 		if (msg_fragm_no(hdr) == 1)
1377 			msg_set_type(hdr, FIRST_FRAGMENT);
1378 		else if (msg_fragm_no(hdr) < msg_nof_fragms(hdr))
1379 			msg_set_type(hdr, FRAGMENT);
1380 		else
1381 			msg_set_type(hdr, LAST_FRAGMENT);
1382 
1383 		if (!tipc_buf_append(reasm_tnlmsg, &skb)) {
1384 			/* Successful but non-complete reassembly? */
1385 			if (*reasm_tnlmsg || link_is_bc_rcvlink(l))
1386 				return 0;
1387 			pr_warn_ratelimited("Unable to reassemble tunnel msg\n");
1388 			return tipc_link_fsm_evt(l, LINK_FAILURE_EVT);
1389 		}
1390 		iskb = skb;
1391 	}
1392 
1393 	do {
1394 		seqno = buf_seqno(iskb);
1395 		if (unlikely(less(seqno, l->drop_point))) {
1396 			kfree_skb(iskb);
1397 			continue;
1398 		}
1399 		if (unlikely(seqno != l->drop_point)) {
1400 			__tipc_skb_queue_sorted(fdefq, seqno, iskb);
1401 			continue;
1402 		}
1403 
1404 		l->drop_point++;
1405 		if (!tipc_data_input(l, iskb, inputq))
1406 			rc |= tipc_link_input(l, iskb, inputq, reasm_skb);
1407 		if (unlikely(rc))
1408 			break;
1409 	} while ((iskb = __tipc_skb_dequeue(fdefq, l->drop_point)));
1410 
1411 	return rc;
1412 }
1413 
1414 /**
1415  * tipc_get_gap_ack_blks - get Gap ACK blocks from PROTOCOL/STATE_MSG
1416  * @ga: returned pointer to the Gap ACK blocks if any
1417  * @l: the tipc link
1418  * @hdr: the PROTOCOL/STATE_MSG header
1419  * @uc: desired Gap ACK blocks type, i.e. unicast (= 1) or broadcast (= 0)
1420  *
1421  * Return: the total Gap ACK blocks size
1422  */
1423 u16 tipc_get_gap_ack_blks(struct tipc_gap_ack_blks **ga, struct tipc_link *l,
1424 			  struct tipc_msg *hdr, bool uc)
1425 {
1426 	struct tipc_gap_ack_blks *p;
1427 	u16 sz = 0;
1428 
1429 	/* Does peer support the Gap ACK blocks feature? */
1430 	if (l->peer_caps & TIPC_GAP_ACK_BLOCK) {
1431 		p = (struct tipc_gap_ack_blks *)msg_data(hdr);
1432 		sz = ntohs(p->len);
1433 		/* Sanity check */
1434 		if (sz == struct_size(p, gacks, size_add(p->ugack_cnt, p->bgack_cnt))) {
1435 			/* Good, check if the desired type exists */
1436 			if ((uc && p->ugack_cnt) || (!uc && p->bgack_cnt))
1437 				goto ok;
1438 		/* Backward compatible: peer might not support bc, but uc? */
1439 		} else if (uc && sz == struct_size(p, gacks, p->ugack_cnt)) {
1440 			if (p->ugack_cnt) {
1441 				p->bgack_cnt = 0;
1442 				goto ok;
1443 			}
1444 		}
1445 	}
1446 	/* Other cases: ignore! */
1447 	p = NULL;
1448 
1449 ok:
1450 	*ga = p;
1451 	return sz;
1452 }
1453 
1454 static u8 __tipc_build_gap_ack_blks(struct tipc_gap_ack_blks *ga,
1455 				    struct tipc_link *l, u8 start_index)
1456 {
1457 	struct tipc_gap_ack *gacks = &ga->gacks[start_index];
1458 	struct sk_buff *skb = skb_peek(&l->deferdq);
1459 	u16 expect, seqno = 0;
1460 	u8 n = 0;
1461 
1462 	if (!skb)
1463 		return 0;
1464 
1465 	expect = buf_seqno(skb);
1466 	skb_queue_walk(&l->deferdq, skb) {
1467 		seqno = buf_seqno(skb);
1468 		if (unlikely(more(seqno, expect))) {
1469 			gacks[n].ack = htons(expect - 1);
1470 			gacks[n].gap = htons(seqno - expect);
1471 			if (++n >= MAX_GAP_ACK_BLKS / 2) {
1472 				pr_info_ratelimited("Gacks on %s: %d, ql: %d!\n",
1473 						    l->name, n,
1474 						    skb_queue_len(&l->deferdq));
1475 				return n;
1476 			}
1477 		} else if (unlikely(less(seqno, expect))) {
1478 			pr_warn("Unexpected skb in deferdq!\n");
1479 			continue;
1480 		}
1481 		expect = seqno + 1;
1482 	}
1483 
1484 	/* last block */
1485 	gacks[n].ack = htons(seqno);
1486 	gacks[n].gap = 0;
1487 	n++;
1488 	return n;
1489 }
1490 
1491 /* tipc_build_gap_ack_blks - build Gap ACK blocks
1492  * @l: tipc unicast link
1493  * @hdr: the tipc message buffer to store the Gap ACK blocks after built
1494  *
1495  * The function builds Gap ACK blocks for both the unicast & broadcast receiver
1496  * links of a certain peer, the buffer after built has the network data format
1497  * as found at the struct tipc_gap_ack_blks definition.
1498  *
1499  * returns the actual allocated memory size
1500  */
1501 static u16 tipc_build_gap_ack_blks(struct tipc_link *l, struct tipc_msg *hdr)
1502 {
1503 	struct tipc_link *bcl = l->bc_rcvlink;
1504 	struct tipc_gap_ack_blks *ga;
1505 	u16 len;
1506 
1507 	ga = (struct tipc_gap_ack_blks *)msg_data(hdr);
1508 
1509 	/* Start with broadcast link first */
1510 	tipc_bcast_lock(bcl->net);
1511 	msg_set_bcast_ack(hdr, bcl->rcv_nxt - 1);
1512 	msg_set_bc_gap(hdr, link_bc_rcv_gap(bcl));
1513 	ga->bgack_cnt = __tipc_build_gap_ack_blks(ga, bcl, 0);
1514 	tipc_bcast_unlock(bcl->net);
1515 
1516 	/* Now for unicast link, but an explicit NACK only (???) */
1517 	ga->ugack_cnt = (msg_seq_gap(hdr)) ?
1518 			__tipc_build_gap_ack_blks(ga, l, ga->bgack_cnt) : 0;
1519 
1520 	/* Total len */
1521 	len = struct_size(ga, gacks, size_add(ga->bgack_cnt, ga->ugack_cnt));
1522 	ga->len = htons(len);
1523 	return len;
1524 }
1525 
1526 /* tipc_link_advance_transmq - advance TIPC link transmq queue by releasing
1527  *			       acked packets, also doing retransmissions if
1528  *			       gaps found
1529  * @l: tipc link with transmq queue to be advanced
1530  * @r: tipc link "receiver" i.e. in case of broadcast (= "l" if unicast)
1531  * @acked: seqno of last packet acked by peer without any gaps before
1532  * @gap: # of gap packets
1533  * @ga: buffer pointer to Gap ACK blocks from peer
1534  * @xmitq: queue for accumulating the retransmitted packets if any
1535  * @retransmitted: returned boolean value if a retransmission is really issued
1536  * @rc: returned code e.g. TIPC_LINK_DOWN_EVT if a repeated retransmit failures
1537  *      happens (- unlikely case)
1538  *
1539  * Return: the number of packets released from the link transmq
1540  */
1541 static int tipc_link_advance_transmq(struct tipc_link *l, struct tipc_link *r,
1542 				     u16 acked, u16 gap,
1543 				     struct tipc_gap_ack_blks *ga,
1544 				     struct sk_buff_head *xmitq,
1545 				     bool *retransmitted, int *rc)
1546 {
1547 	struct tipc_gap_ack_blks *last_ga = r->last_ga, *this_ga = NULL;
1548 	struct tipc_gap_ack *gacks = NULL;
1549 	struct sk_buff *skb, *_skb, *tmp;
1550 	struct tipc_msg *hdr;
1551 	u32 qlen = skb_queue_len(&l->transmq);
1552 	u16 nacked = acked, ngap = gap, gack_cnt = 0;
1553 	u16 bc_ack = l->bc_rcvlink->rcv_nxt - 1;
1554 	u16 ack = l->rcv_nxt - 1;
1555 	u16 seqno, n = 0;
1556 	u16 end = r->acked, start = end, offset = r->last_gap;
1557 	u16 si = (last_ga) ? last_ga->start_index : 0;
1558 	bool is_uc = !link_is_bc_sndlink(l);
1559 	bool bc_has_acked = false;
1560 
1561 	trace_tipc_link_retrans(r, acked + 1, acked + gap, &l->transmq);
1562 
1563 	/* Determine Gap ACK blocks if any for the particular link */
1564 	if (ga && is_uc) {
1565 		/* Get the Gap ACKs, uc part */
1566 		gack_cnt = ga->ugack_cnt;
1567 		gacks = &ga->gacks[ga->bgack_cnt];
1568 	} else if (ga) {
1569 		/* Copy the Gap ACKs, bc part, for later renewal if needed */
1570 		this_ga = kmemdup(ga, struct_size(ga, gacks, ga->bgack_cnt),
1571 				  GFP_ATOMIC);
1572 		if (likely(this_ga)) {
1573 			this_ga->start_index = 0;
1574 			/* Start with the bc Gap ACKs */
1575 			gack_cnt = this_ga->bgack_cnt;
1576 			gacks = &this_ga->gacks[0];
1577 		} else {
1578 			/* Hmm, we can get in trouble..., simply ignore it */
1579 			pr_warn_ratelimited("Ignoring bc Gap ACKs, no memory\n");
1580 		}
1581 	}
1582 
1583 	/* Advance the link transmq */
1584 	skb_queue_walk_safe(&l->transmq, skb, tmp) {
1585 		seqno = buf_seqno(skb);
1586 
1587 next_gap_ack:
1588 		if (less_eq(seqno, nacked)) {
1589 			if (is_uc)
1590 				goto release;
1591 			/* Skip packets peer has already acked */
1592 			if (!more(seqno, r->acked))
1593 				continue;
1594 			/* Get the next of last Gap ACK blocks */
1595 			while (more(seqno, end)) {
1596 				if (!last_ga || si >= last_ga->bgack_cnt)
1597 					break;
1598 				start = end + offset + 1;
1599 				end = ntohs(last_ga->gacks[si].ack);
1600 				offset = ntohs(last_ga->gacks[si].gap);
1601 				si++;
1602 				WARN_ONCE(more(start, end) ||
1603 					  (!offset &&
1604 					   si < last_ga->bgack_cnt) ||
1605 					  si > MAX_GAP_ACK_BLKS,
1606 					  "Corrupted Gap ACK: %d %d %d %d %d\n",
1607 					  start, end, offset, si,
1608 					  last_ga->bgack_cnt);
1609 			}
1610 			/* Check against the last Gap ACK block */
1611 			if (tipc_in_range(seqno, start, end))
1612 				continue;
1613 			/* Update/release the packet peer is acking */
1614 			bc_has_acked = true;
1615 			if (--TIPC_SKB_CB(skb)->ackers)
1616 				continue;
1617 release:
1618 			/* release skb */
1619 			__skb_unlink(skb, &l->transmq);
1620 			kfree_skb(skb);
1621 		} else if (less_eq(seqno, nacked + ngap)) {
1622 			/* First gap: check if repeated retrans failures? */
1623 			if (unlikely(seqno == acked + 1 &&
1624 				     link_retransmit_failure(l, r, rc))) {
1625 				/* Ignore this bc Gap ACKs if any */
1626 				kfree(this_ga);
1627 				this_ga = NULL;
1628 				break;
1629 			}
1630 			/* retransmit skb if unrestricted*/
1631 			if (time_before(jiffies, TIPC_SKB_CB(skb)->nxt_retr))
1632 				continue;
1633 			tipc_link_set_skb_retransmit_time(skb, l);
1634 			_skb = pskb_copy(skb, GFP_ATOMIC);
1635 			if (!_skb)
1636 				continue;
1637 			hdr = buf_msg(_skb);
1638 			msg_set_ack(hdr, ack);
1639 			msg_set_bcast_ack(hdr, bc_ack);
1640 			_skb->priority = TC_PRIO_CONTROL;
1641 			__skb_queue_tail(xmitq, _skb);
1642 			l->stats.retransmitted++;
1643 			if (!is_uc)
1644 				r->stats.retransmitted++;
1645 			*retransmitted = true;
1646 			/* Increase actual retrans counter & mark first time */
1647 			if (!TIPC_SKB_CB(skb)->retr_cnt++)
1648 				TIPC_SKB_CB(skb)->retr_stamp = jiffies;
1649 		} else {
1650 			/* retry with Gap ACK blocks if any */
1651 			if (n >= gack_cnt)
1652 				break;
1653 			nacked = ntohs(gacks[n].ack);
1654 			ngap = ntohs(gacks[n].gap);
1655 			n++;
1656 			goto next_gap_ack;
1657 		}
1658 	}
1659 
1660 	/* Renew last Gap ACK blocks for bc if needed */
1661 	if (bc_has_acked) {
1662 		if (this_ga) {
1663 			kfree(last_ga);
1664 			r->last_ga = this_ga;
1665 			r->last_gap = gap;
1666 		} else if (last_ga) {
1667 			if (less(acked, start)) {
1668 				si--;
1669 				offset = start - acked - 1;
1670 			} else if (less(acked, end)) {
1671 				acked = end;
1672 			}
1673 			if (si < last_ga->bgack_cnt) {
1674 				last_ga->start_index = si;
1675 				r->last_gap = offset;
1676 			} else {
1677 				kfree(last_ga);
1678 				r->last_ga = NULL;
1679 				r->last_gap = 0;
1680 			}
1681 		} else {
1682 			r->last_gap = 0;
1683 		}
1684 		r->acked = acked;
1685 	} else {
1686 		kfree(this_ga);
1687 	}
1688 
1689 	return qlen - skb_queue_len(&l->transmq);
1690 }
1691 
1692 /* tipc_link_build_state_msg: prepare link state message for transmission
1693  *
1694  * Note that sending of broadcast ack is coordinated among nodes, to reduce
1695  * risk of ack storms towards the sender
1696  */
1697 int tipc_link_build_state_msg(struct tipc_link *l, struct sk_buff_head *xmitq)
1698 {
1699 	if (!l)
1700 		return 0;
1701 
1702 	/* Broadcast ACK must be sent via a unicast link => defer to caller */
1703 	if (link_is_bc_rcvlink(l)) {
1704 		if (((l->rcv_nxt ^ tipc_own_addr(l->net)) & 0xf) != 0xf)
1705 			return 0;
1706 		l->rcv_unacked = 0;
1707 
1708 		/* Use snd_nxt to store peer's snd_nxt in broadcast rcv link */
1709 		l->snd_nxt = l->rcv_nxt;
1710 		return TIPC_LINK_SND_STATE;
1711 	}
1712 	/* Unicast ACK */
1713 	l->rcv_unacked = 0;
1714 	l->stats.sent_acks++;
1715 	tipc_link_build_proto_msg(l, STATE_MSG, 0, 0, 0, 0, 0, xmitq);
1716 	return 0;
1717 }
1718 
1719 /* tipc_link_build_reset_msg: prepare link RESET or ACTIVATE message
1720  */
1721 void tipc_link_build_reset_msg(struct tipc_link *l, struct sk_buff_head *xmitq)
1722 {
1723 	int mtyp = RESET_MSG;
1724 	struct sk_buff *skb;
1725 
1726 	if (l->state == LINK_ESTABLISHING)
1727 		mtyp = ACTIVATE_MSG;
1728 
1729 	tipc_link_build_proto_msg(l, mtyp, 0, 0, 0, 0, 0, xmitq);
1730 
1731 	/* Inform peer that this endpoint is going down if applicable */
1732 	skb = skb_peek_tail(xmitq);
1733 	if (skb && (l->state == LINK_RESET))
1734 		msg_set_peer_stopping(buf_msg(skb), 1);
1735 }
1736 
1737 /* tipc_link_build_nack_msg: prepare link nack message for transmission
1738  * Note that sending of broadcast NACK is coordinated among nodes, to
1739  * reduce the risk of NACK storms towards the sender
1740  */
1741 static int tipc_link_build_nack_msg(struct tipc_link *l,
1742 				    struct sk_buff_head *xmitq)
1743 {
1744 	u32 def_cnt = ++l->stats.deferred_recv;
1745 	struct sk_buff_head *dfq = &l->deferdq;
1746 	u32 defq_len = skb_queue_len(dfq);
1747 	int match1, match2;
1748 
1749 	if (link_is_bc_rcvlink(l)) {
1750 		match1 = def_cnt & 0xf;
1751 		match2 = tipc_own_addr(l->net) & 0xf;
1752 		if (match1 == match2)
1753 			return TIPC_LINK_SND_STATE;
1754 		return 0;
1755 	}
1756 
1757 	if (defq_len >= 3 && !((defq_len - 3) % 16)) {
1758 		u16 rcvgap = buf_seqno(skb_peek(dfq)) - l->rcv_nxt;
1759 
1760 		tipc_link_build_proto_msg(l, STATE_MSG, 0, 0,
1761 					  rcvgap, 0, 0, xmitq);
1762 	}
1763 	return 0;
1764 }
1765 
1766 /* tipc_link_rcv - process TIPC packets/messages arriving from off-node
1767  * @l: the link that should handle the message
1768  * @skb: TIPC packet
1769  * @xmitq: queue to place packets to be sent after this call
1770  */
1771 int tipc_link_rcv(struct tipc_link *l, struct sk_buff *skb,
1772 		  struct sk_buff_head *xmitq)
1773 {
1774 	struct sk_buff_head *defq = &l->deferdq;
1775 	struct tipc_msg *hdr = buf_msg(skb);
1776 	u16 seqno, rcv_nxt, win_lim;
1777 	int released = 0;
1778 	int rc = 0;
1779 
1780 	/* Verify and update link state */
1781 	if (unlikely(msg_user(hdr) == LINK_PROTOCOL))
1782 		return tipc_link_proto_rcv(l, skb, xmitq);
1783 
1784 	/* Don't send probe at next timeout expiration */
1785 	l->silent_intv_cnt = 0;
1786 
1787 	do {
1788 		hdr = buf_msg(skb);
1789 		seqno = msg_seqno(hdr);
1790 		rcv_nxt = l->rcv_nxt;
1791 		win_lim = rcv_nxt + TIPC_MAX_LINK_WIN;
1792 
1793 		if (unlikely(!link_is_up(l))) {
1794 			if (l->state == LINK_ESTABLISHING)
1795 				rc = TIPC_LINK_UP_EVT;
1796 			kfree_skb(skb);
1797 			break;
1798 		}
1799 
1800 		/* Drop if outside receive window */
1801 		if (unlikely(less(seqno, rcv_nxt) || more(seqno, win_lim))) {
1802 			l->stats.duplicates++;
1803 			kfree_skb(skb);
1804 			break;
1805 		}
1806 		released += tipc_link_advance_transmq(l, l, msg_ack(hdr), 0,
1807 						      NULL, NULL, NULL, NULL);
1808 
1809 		/* Defer delivery if sequence gap */
1810 		if (unlikely(seqno != rcv_nxt)) {
1811 			if (!__tipc_skb_queue_sorted(defq, seqno, skb))
1812 				l->stats.duplicates++;
1813 			rc |= tipc_link_build_nack_msg(l, xmitq);
1814 			break;
1815 		}
1816 
1817 		/* Deliver packet */
1818 		l->rcv_nxt++;
1819 		l->stats.recv_pkts++;
1820 
1821 		if (unlikely(msg_user(hdr) == TUNNEL_PROTOCOL))
1822 			rc |= tipc_link_tnl_rcv(l, skb, l->inputq);
1823 		else if (!tipc_data_input(l, skb, l->inputq))
1824 			rc |= tipc_link_input(l, skb, l->inputq, &l->reasm_buf);
1825 		if (unlikely(++l->rcv_unacked >= TIPC_MIN_LINK_WIN))
1826 			rc |= tipc_link_build_state_msg(l, xmitq);
1827 		if (unlikely(rc & ~TIPC_LINK_SND_STATE))
1828 			break;
1829 	} while ((skb = __tipc_skb_dequeue(defq, l->rcv_nxt)));
1830 
1831 	/* Forward queues and wake up waiting users */
1832 	if (released) {
1833 		tipc_link_update_cwin(l, released, 0);
1834 		tipc_link_advance_backlog(l, xmitq);
1835 		if (unlikely(!skb_queue_empty(&l->wakeupq)))
1836 			link_prepare_wakeup(l);
1837 	}
1838 	return rc;
1839 }
1840 
1841 static void tipc_link_build_proto_msg(struct tipc_link *l, int mtyp, bool probe,
1842 				      bool probe_reply, u16 rcvgap,
1843 				      int tolerance, int priority,
1844 				      struct sk_buff_head *xmitq)
1845 {
1846 	struct tipc_mon_state *mstate = &l->mon_state;
1847 	struct sk_buff_head *dfq = &l->deferdq;
1848 	struct tipc_link *bcl = l->bc_rcvlink;
1849 	struct tipc_msg *hdr;
1850 	struct sk_buff *skb;
1851 	bool node_up = link_is_up(bcl);
1852 	u16 glen = 0, bc_rcvgap = 0;
1853 	int dlen = 0;
1854 	void *data;
1855 
1856 	/* Don't send protocol message during reset or link failover */
1857 	if (tipc_link_is_blocked(l))
1858 		return;
1859 
1860 	if (!tipc_link_is_up(l) && (mtyp == STATE_MSG))
1861 		return;
1862 
1863 	if ((probe || probe_reply) && !skb_queue_empty(dfq))
1864 		rcvgap = buf_seqno(skb_peek(dfq)) - l->rcv_nxt;
1865 
1866 	skb = tipc_msg_create(LINK_PROTOCOL, mtyp, INT_H_SIZE,
1867 			      tipc_max_domain_size + MAX_GAP_ACK_BLKS_SZ,
1868 			      l->addr, tipc_own_addr(l->net), 0, 0, 0);
1869 	if (!skb)
1870 		return;
1871 
1872 	hdr = buf_msg(skb);
1873 	data = msg_data(hdr);
1874 	msg_set_session(hdr, l->session);
1875 	msg_set_bearer_id(hdr, l->bearer_id);
1876 	msg_set_net_plane(hdr, l->net_plane);
1877 	msg_set_next_sent(hdr, l->snd_nxt);
1878 	msg_set_ack(hdr, l->rcv_nxt - 1);
1879 	msg_set_bcast_ack(hdr, bcl->rcv_nxt - 1);
1880 	msg_set_bc_ack_invalid(hdr, !node_up);
1881 	msg_set_last_bcast(hdr, l->bc_sndlink->snd_nxt - 1);
1882 	msg_set_link_tolerance(hdr, tolerance);
1883 	msg_set_linkprio(hdr, priority);
1884 	msg_set_redundant_link(hdr, node_up);
1885 	msg_set_seq_gap(hdr, 0);
1886 	msg_set_seqno(hdr, l->snd_nxt + U16_MAX / 2);
1887 
1888 	if (mtyp == STATE_MSG) {
1889 		if (l->peer_caps & TIPC_LINK_PROTO_SEQNO)
1890 			msg_set_seqno(hdr, l->snd_nxt_state++);
1891 		msg_set_seq_gap(hdr, rcvgap);
1892 		bc_rcvgap = link_bc_rcv_gap(bcl);
1893 		msg_set_bc_gap(hdr, bc_rcvgap);
1894 		msg_set_probe(hdr, probe);
1895 		msg_set_is_keepalive(hdr, probe || probe_reply);
1896 		if (l->peer_caps & TIPC_GAP_ACK_BLOCK)
1897 			glen = tipc_build_gap_ack_blks(l, hdr);
1898 		tipc_mon_prep(l->net, data + glen, &dlen, mstate, l->bearer_id);
1899 		msg_set_size(hdr, INT_H_SIZE + glen + dlen);
1900 		skb_trim(skb, INT_H_SIZE + glen + dlen);
1901 		l->stats.sent_states++;
1902 		l->rcv_unacked = 0;
1903 	} else {
1904 		/* RESET_MSG or ACTIVATE_MSG */
1905 		if (mtyp == ACTIVATE_MSG) {
1906 			msg_set_dest_session_valid(hdr, 1);
1907 			msg_set_dest_session(hdr, l->peer_session);
1908 		}
1909 		msg_set_max_pkt(hdr, l->advertised_mtu);
1910 		strcpy(data, l->if_name);
1911 		msg_set_size(hdr, INT_H_SIZE + TIPC_MAX_IF_NAME);
1912 		skb_trim(skb, INT_H_SIZE + TIPC_MAX_IF_NAME);
1913 	}
1914 	if (probe)
1915 		l->stats.sent_probes++;
1916 	if (rcvgap)
1917 		l->stats.sent_nacks++;
1918 	if (bc_rcvgap)
1919 		bcl->stats.sent_nacks++;
1920 	skb->priority = TC_PRIO_CONTROL;
1921 	__skb_queue_tail(xmitq, skb);
1922 	trace_tipc_proto_build(skb, false, l->name);
1923 }
1924 
1925 void tipc_link_create_dummy_tnl_msg(struct tipc_link *l,
1926 				    struct sk_buff_head *xmitq)
1927 {
1928 	u32 onode = tipc_own_addr(l->net);
1929 	struct tipc_msg *hdr, *ihdr;
1930 	struct sk_buff_head tnlq;
1931 	struct sk_buff *skb;
1932 	u32 dnode = l->addr;
1933 
1934 	__skb_queue_head_init(&tnlq);
1935 	skb = tipc_msg_create(TUNNEL_PROTOCOL, FAILOVER_MSG,
1936 			      INT_H_SIZE, BASIC_H_SIZE,
1937 			      dnode, onode, 0, 0, 0);
1938 	if (!skb) {
1939 		pr_warn("%sunable to create tunnel packet\n", link_co_err);
1940 		return;
1941 	}
1942 
1943 	hdr = buf_msg(skb);
1944 	msg_set_msgcnt(hdr, 1);
1945 	msg_set_bearer_id(hdr, l->peer_bearer_id);
1946 
1947 	ihdr = (struct tipc_msg *)msg_data(hdr);
1948 	tipc_msg_init(onode, ihdr, TIPC_LOW_IMPORTANCE, TIPC_DIRECT_MSG,
1949 		      BASIC_H_SIZE, dnode);
1950 	msg_set_errcode(ihdr, TIPC_ERR_NO_PORT);
1951 	__skb_queue_tail(&tnlq, skb);
1952 	tipc_link_xmit(l, &tnlq, xmitq);
1953 }
1954 
1955 /* tipc_link_tnl_prepare(): prepare and return a list of tunnel packets
1956  * with contents of the link's transmit and backlog queues.
1957  */
1958 void tipc_link_tnl_prepare(struct tipc_link *l, struct tipc_link *tnl,
1959 			   int mtyp, struct sk_buff_head *xmitq)
1960 {
1961 	struct sk_buff_head *fdefq = &tnl->failover_deferdq;
1962 	struct sk_buff *skb, *tnlskb;
1963 	struct tipc_msg *hdr, tnlhdr;
1964 	struct sk_buff_head *queue = &l->transmq;
1965 	struct sk_buff_head tmpxq, tnlq, frags;
1966 	u16 pktlen, pktcnt, seqno = l->snd_nxt;
1967 	bool pktcnt_need_update = false;
1968 	u16 syncpt;
1969 	int rc;
1970 
1971 	if (!tnl)
1972 		return;
1973 
1974 	__skb_queue_head_init(&tnlq);
1975 	/* Link Synching:
1976 	 * From now on, send only one single ("dummy") SYNCH message
1977 	 * to peer. The SYNCH message does not contain any data, just
1978 	 * a header conveying the synch point to the peer.
1979 	 */
1980 	if (mtyp == SYNCH_MSG && (tnl->peer_caps & TIPC_TUNNEL_ENHANCED)) {
1981 		tnlskb = tipc_msg_create(TUNNEL_PROTOCOL, SYNCH_MSG,
1982 					 INT_H_SIZE, 0, l->addr,
1983 					 tipc_own_addr(l->net),
1984 					 0, 0, 0);
1985 		if (!tnlskb) {
1986 			pr_warn("%sunable to create dummy SYNCH_MSG\n",
1987 				link_co_err);
1988 			return;
1989 		}
1990 
1991 		hdr = buf_msg(tnlskb);
1992 		syncpt = l->snd_nxt + skb_queue_len(&l->backlogq) - 1;
1993 		msg_set_syncpt(hdr, syncpt);
1994 		msg_set_bearer_id(hdr, l->peer_bearer_id);
1995 		__skb_queue_tail(&tnlq, tnlskb);
1996 		tipc_link_xmit(tnl, &tnlq, xmitq);
1997 		return;
1998 	}
1999 
2000 	__skb_queue_head_init(&tmpxq);
2001 	__skb_queue_head_init(&frags);
2002 	/* At least one packet required for safe algorithm => add dummy */
2003 	skb = tipc_msg_create(TIPC_LOW_IMPORTANCE, TIPC_DIRECT_MSG,
2004 			      BASIC_H_SIZE, 0, l->addr, tipc_own_addr(l->net),
2005 			      0, 0, TIPC_ERR_NO_PORT);
2006 	if (!skb) {
2007 		pr_warn("%sunable to create tunnel packet\n", link_co_err);
2008 		return;
2009 	}
2010 	__skb_queue_tail(&tnlq, skb);
2011 	tipc_link_xmit(l, &tnlq, &tmpxq);
2012 	__skb_queue_purge(&tmpxq);
2013 
2014 	/* Initialize reusable tunnel packet header */
2015 	tipc_msg_init(tipc_own_addr(l->net), &tnlhdr, TUNNEL_PROTOCOL,
2016 		      mtyp, INT_H_SIZE, l->addr);
2017 	if (mtyp == SYNCH_MSG)
2018 		pktcnt = l->snd_nxt - buf_seqno(skb_peek(&l->transmq));
2019 	else
2020 		pktcnt = skb_queue_len(&l->transmq);
2021 	pktcnt += skb_queue_len(&l->backlogq);
2022 	msg_set_msgcnt(&tnlhdr, pktcnt);
2023 	msg_set_bearer_id(&tnlhdr, l->peer_bearer_id);
2024 tnl:
2025 	/* Wrap each packet into a tunnel packet */
2026 	skb_queue_walk(queue, skb) {
2027 		hdr = buf_msg(skb);
2028 		if (queue == &l->backlogq)
2029 			msg_set_seqno(hdr, seqno++);
2030 		pktlen = msg_size(hdr);
2031 
2032 		/* Tunnel link MTU is not large enough? This could be
2033 		 * due to:
2034 		 * 1) Link MTU has just changed or set differently;
2035 		 * 2) Or FAILOVER on the top of a SYNCH message
2036 		 *
2037 		 * The 2nd case should not happen if peer supports
2038 		 * TIPC_TUNNEL_ENHANCED
2039 		 */
2040 		if (pktlen > tnl->mtu - INT_H_SIZE) {
2041 			if (mtyp == FAILOVER_MSG &&
2042 			    (tnl->peer_caps & TIPC_TUNNEL_ENHANCED)) {
2043 				rc = tipc_msg_fragment(skb, &tnlhdr, tnl->mtu,
2044 						       &frags);
2045 				if (rc) {
2046 					pr_warn("%sunable to frag msg: rc %d\n",
2047 						link_co_err, rc);
2048 					return;
2049 				}
2050 				pktcnt += skb_queue_len(&frags) - 1;
2051 				pktcnt_need_update = true;
2052 				skb_queue_splice_tail_init(&frags, &tnlq);
2053 				continue;
2054 			}
2055 			/* Unluckily, peer doesn't have TIPC_TUNNEL_ENHANCED
2056 			 * => Just warn it and return!
2057 			 */
2058 			pr_warn_ratelimited("%stoo large msg <%d, %d>: %d!\n",
2059 					    link_co_err, msg_user(hdr),
2060 					    msg_type(hdr), msg_size(hdr));
2061 			return;
2062 		}
2063 
2064 		msg_set_size(&tnlhdr, pktlen + INT_H_SIZE);
2065 		tnlskb = tipc_buf_acquire(pktlen + INT_H_SIZE, GFP_ATOMIC);
2066 		if (!tnlskb) {
2067 			pr_warn("%sunable to send packet\n", link_co_err);
2068 			return;
2069 		}
2070 		skb_copy_to_linear_data(tnlskb, &tnlhdr, INT_H_SIZE);
2071 		skb_copy_to_linear_data_offset(tnlskb, INT_H_SIZE, hdr, pktlen);
2072 		__skb_queue_tail(&tnlq, tnlskb);
2073 	}
2074 	if (queue != &l->backlogq) {
2075 		queue = &l->backlogq;
2076 		goto tnl;
2077 	}
2078 
2079 	if (pktcnt_need_update)
2080 		skb_queue_walk(&tnlq, skb) {
2081 			hdr = buf_msg(skb);
2082 			msg_set_msgcnt(hdr, pktcnt);
2083 		}
2084 
2085 	tipc_link_xmit(tnl, &tnlq, xmitq);
2086 
2087 	if (mtyp == FAILOVER_MSG) {
2088 		tnl->drop_point = l->rcv_nxt;
2089 		tnl->failover_reasm_skb = l->reasm_buf;
2090 		l->reasm_buf = NULL;
2091 
2092 		/* Failover the link's deferdq */
2093 		if (unlikely(!skb_queue_empty(fdefq))) {
2094 			pr_warn("Link failover deferdq not empty: %d!\n",
2095 				skb_queue_len(fdefq));
2096 			__skb_queue_purge(fdefq);
2097 		}
2098 		skb_queue_splice_init(&l->deferdq, fdefq);
2099 	}
2100 }
2101 
2102 /**
2103  * tipc_link_failover_prepare() - prepare tnl for link failover
2104  *
2105  * This is a special version of the precursor - tipc_link_tnl_prepare(),
2106  * see the tipc_node_link_failover() for details
2107  *
2108  * @l: failover link
2109  * @tnl: tunnel link
2110  * @xmitq: queue for messages to be xmited
2111  */
2112 void tipc_link_failover_prepare(struct tipc_link *l, struct tipc_link *tnl,
2113 				struct sk_buff_head *xmitq)
2114 {
2115 	struct sk_buff_head *fdefq = &tnl->failover_deferdq;
2116 
2117 	tipc_link_create_dummy_tnl_msg(tnl, xmitq);
2118 
2119 	/* This failover link endpoint was never established before,
2120 	 * so it has not received anything from peer.
2121 	 * Otherwise, it must be a normal failover situation or the
2122 	 * node has entered SELF_DOWN_PEER_LEAVING and both peer nodes
2123 	 * would have to start over from scratch instead.
2124 	 */
2125 	tnl->drop_point = 1;
2126 	tnl->failover_reasm_skb = NULL;
2127 
2128 	/* Initiate the link's failover deferdq */
2129 	if (unlikely(!skb_queue_empty(fdefq))) {
2130 		pr_warn("Link failover deferdq not empty: %d!\n",
2131 			skb_queue_len(fdefq));
2132 		__skb_queue_purge(fdefq);
2133 	}
2134 }
2135 
2136 /* tipc_link_validate_msg(): validate message against current link state
2137  * Returns true if message should be accepted, otherwise false
2138  */
2139 bool tipc_link_validate_msg(struct tipc_link *l, struct tipc_msg *hdr)
2140 {
2141 	u16 curr_session = l->peer_session;
2142 	u16 session = msg_session(hdr);
2143 	int mtyp = msg_type(hdr);
2144 
2145 	if (msg_user(hdr) != LINK_PROTOCOL)
2146 		return true;
2147 
2148 	switch (mtyp) {
2149 	case RESET_MSG:
2150 		if (!l->in_session)
2151 			return true;
2152 		/* Accept only RESET with new session number */
2153 		return more(session, curr_session);
2154 	case ACTIVATE_MSG:
2155 		if (!l->in_session)
2156 			return true;
2157 		/* Accept only ACTIVATE with new or current session number */
2158 		return !less(session, curr_session);
2159 	case STATE_MSG:
2160 		/* Accept only STATE with current session number */
2161 		if (!l->in_session)
2162 			return false;
2163 		if (session != curr_session)
2164 			return false;
2165 		/* Extra sanity check */
2166 		if (!link_is_up(l) && msg_ack(hdr))
2167 			return false;
2168 		if (!(l->peer_caps & TIPC_LINK_PROTO_SEQNO))
2169 			return true;
2170 		/* Accept only STATE with new sequence number */
2171 		return !less(msg_seqno(hdr), l->rcv_nxt_state);
2172 	default:
2173 		return false;
2174 	}
2175 }
2176 
2177 /* tipc_link_proto_rcv(): receive link level protocol message :
2178  * Note that network plane id propagates through the network, and may
2179  * change at any time. The node with lowest numerical id determines
2180  * network plane
2181  */
2182 static int tipc_link_proto_rcv(struct tipc_link *l, struct sk_buff *skb,
2183 			       struct sk_buff_head *xmitq)
2184 {
2185 	struct tipc_msg *hdr = buf_msg(skb);
2186 	struct tipc_gap_ack_blks *ga = NULL;
2187 	bool reply = msg_probe(hdr), retransmitted = false;
2188 	u32 dlen = msg_data_sz(hdr), glen = 0, msg_max;
2189 	u16 peers_snd_nxt =  msg_next_sent(hdr);
2190 	u16 peers_tol = msg_link_tolerance(hdr);
2191 	u16 peers_prio = msg_linkprio(hdr);
2192 	u16 gap = msg_seq_gap(hdr);
2193 	u16 ack = msg_ack(hdr);
2194 	u16 rcv_nxt = l->rcv_nxt;
2195 	u16 rcvgap = 0;
2196 	int mtyp = msg_type(hdr);
2197 	int rc = 0, released;
2198 	char *if_name;
2199 	void *data;
2200 
2201 	trace_tipc_proto_rcv(skb, false, l->name);
2202 
2203 	if (dlen > U16_MAX)
2204 		goto exit;
2205 
2206 	if (tipc_link_is_blocked(l) || !xmitq)
2207 		goto exit;
2208 
2209 	if (tipc_own_addr(l->net) > msg_prevnode(hdr))
2210 		l->net_plane = msg_net_plane(hdr);
2211 
2212 	if (skb_linearize(skb))
2213 		goto exit;
2214 
2215 	hdr = buf_msg(skb);
2216 	data = msg_data(hdr);
2217 
2218 	if (!tipc_link_validate_msg(l, hdr)) {
2219 		trace_tipc_skb_dump(skb, false, "PROTO invalid (1)!");
2220 		trace_tipc_link_dump(l, TIPC_DUMP_NONE, "PROTO invalid (1)!");
2221 		goto exit;
2222 	}
2223 
2224 	switch (mtyp) {
2225 	case RESET_MSG:
2226 	case ACTIVATE_MSG:
2227 		msg_max = msg_max_pkt(hdr);
2228 		if (msg_max < tipc_bearer_min_mtu(l->net, l->bearer_id))
2229 			break;
2230 		/* Complete own link name with peer's interface name */
2231 		if_name =  strrchr(l->name, ':') + 1;
2232 		if (sizeof(l->name) - (if_name - l->name) <= TIPC_MAX_IF_NAME)
2233 			break;
2234 		if (msg_data_sz(hdr) < TIPC_MAX_IF_NAME)
2235 			break;
2236 		strncpy(if_name, data, TIPC_MAX_IF_NAME);
2237 
2238 		/* Update own tolerance if peer indicates a non-zero value */
2239 		if (tipc_in_range(peers_tol, TIPC_MIN_LINK_TOL, TIPC_MAX_LINK_TOL)) {
2240 			l->tolerance = peers_tol;
2241 			l->bc_rcvlink->tolerance = peers_tol;
2242 		}
2243 		/* Update own priority if peer's priority is higher */
2244 		if (tipc_in_range(peers_prio, l->priority + 1, TIPC_MAX_LINK_PRI))
2245 			l->priority = peers_prio;
2246 
2247 		/* If peer is going down we want full re-establish cycle */
2248 		if (msg_peer_stopping(hdr)) {
2249 			rc = tipc_link_fsm_evt(l, LINK_FAILURE_EVT);
2250 			break;
2251 		}
2252 
2253 		/* If this endpoint was re-created while peer was ESTABLISHING
2254 		 * it doesn't know current session number. Force re-synch.
2255 		 */
2256 		if (mtyp == ACTIVATE_MSG && msg_dest_session_valid(hdr) &&
2257 		    l->session != msg_dest_session(hdr)) {
2258 			if (less(l->session, msg_dest_session(hdr)))
2259 				l->session = msg_dest_session(hdr) + 1;
2260 			break;
2261 		}
2262 
2263 		/* ACTIVATE_MSG serves as PEER_RESET if link is already down */
2264 		if (mtyp == RESET_MSG || !link_is_up(l))
2265 			rc = tipc_link_fsm_evt(l, LINK_PEER_RESET_EVT);
2266 
2267 		/* ACTIVATE_MSG takes up link if it was already locally reset */
2268 		if (mtyp == ACTIVATE_MSG && l->state == LINK_ESTABLISHING)
2269 			rc = TIPC_LINK_UP_EVT;
2270 
2271 		l->peer_session = msg_session(hdr);
2272 		l->in_session = true;
2273 		l->peer_bearer_id = msg_bearer_id(hdr);
2274 		if (l->mtu > msg_max)
2275 			l->mtu = msg_max;
2276 		break;
2277 
2278 	case STATE_MSG:
2279 		/* Validate Gap ACK blocks, drop if invalid */
2280 		glen = tipc_get_gap_ack_blks(&ga, l, hdr, true);
2281 		if (glen > dlen)
2282 			break;
2283 
2284 		l->rcv_nxt_state = msg_seqno(hdr) + 1;
2285 
2286 		/* Update own tolerance if peer indicates a non-zero value */
2287 		if (tipc_in_range(peers_tol, TIPC_MIN_LINK_TOL, TIPC_MAX_LINK_TOL)) {
2288 			l->tolerance = peers_tol;
2289 			l->bc_rcvlink->tolerance = peers_tol;
2290 		}
2291 		/* Update own prio if peer indicates a different value */
2292 		if ((peers_prio != l->priority) &&
2293 		    tipc_in_range(peers_prio, 1, TIPC_MAX_LINK_PRI)) {
2294 			l->priority = peers_prio;
2295 			rc = tipc_link_fsm_evt(l, LINK_FAILURE_EVT);
2296 		}
2297 
2298 		l->silent_intv_cnt = 0;
2299 		l->stats.recv_states++;
2300 		if (msg_probe(hdr))
2301 			l->stats.recv_probes++;
2302 
2303 		if (!link_is_up(l)) {
2304 			if (l->state == LINK_ESTABLISHING)
2305 				rc = TIPC_LINK_UP_EVT;
2306 			break;
2307 		}
2308 
2309 		tipc_mon_rcv(l->net, data + glen, dlen - glen, l->addr,
2310 			     &l->mon_state, l->bearer_id);
2311 
2312 		/* Send NACK if peer has sent pkts we haven't received yet */
2313 		if ((reply || msg_is_keepalive(hdr)) &&
2314 		    more(peers_snd_nxt, rcv_nxt) &&
2315 		    !tipc_link_is_synching(l) &&
2316 		    skb_queue_empty(&l->deferdq))
2317 			rcvgap = peers_snd_nxt - l->rcv_nxt;
2318 		if (rcvgap || reply)
2319 			tipc_link_build_proto_msg(l, STATE_MSG, 0, reply,
2320 						  rcvgap, 0, 0, xmitq);
2321 
2322 		released = tipc_link_advance_transmq(l, l, ack, gap, ga, xmitq,
2323 						     &retransmitted, &rc);
2324 		if (gap)
2325 			l->stats.recv_nacks++;
2326 		if (released || retransmitted)
2327 			tipc_link_update_cwin(l, released, retransmitted);
2328 		if (released)
2329 			tipc_link_advance_backlog(l, xmitq);
2330 		if (unlikely(!skb_queue_empty(&l->wakeupq)))
2331 			link_prepare_wakeup(l);
2332 	}
2333 exit:
2334 	kfree_skb(skb);
2335 	return rc;
2336 }
2337 
2338 /* tipc_link_build_bc_proto_msg() - create broadcast protocol message
2339  */
2340 static bool tipc_link_build_bc_proto_msg(struct tipc_link *l, bool bcast,
2341 					 u16 peers_snd_nxt,
2342 					 struct sk_buff_head *xmitq)
2343 {
2344 	struct sk_buff *skb;
2345 	struct tipc_msg *hdr;
2346 	struct sk_buff *dfrd_skb = skb_peek(&l->deferdq);
2347 	u16 ack = l->rcv_nxt - 1;
2348 	u16 gap_to = peers_snd_nxt - 1;
2349 
2350 	skb = tipc_msg_create(BCAST_PROTOCOL, STATE_MSG, INT_H_SIZE,
2351 			      0, l->addr, tipc_own_addr(l->net), 0, 0, 0);
2352 	if (!skb)
2353 		return false;
2354 	hdr = buf_msg(skb);
2355 	msg_set_last_bcast(hdr, l->bc_sndlink->snd_nxt - 1);
2356 	msg_set_bcast_ack(hdr, ack);
2357 	msg_set_bcgap_after(hdr, ack);
2358 	if (dfrd_skb)
2359 		gap_to = buf_seqno(dfrd_skb) - 1;
2360 	msg_set_bcgap_to(hdr, gap_to);
2361 	msg_set_non_seq(hdr, bcast);
2362 	__skb_queue_tail(xmitq, skb);
2363 	return true;
2364 }
2365 
2366 /* tipc_link_build_bc_init_msg() - synchronize broadcast link endpoints.
2367  *
2368  * Give a newly added peer node the sequence number where it should
2369  * start receiving and acking broadcast packets.
2370  */
2371 static void tipc_link_build_bc_init_msg(struct tipc_link *l,
2372 					struct sk_buff_head *xmitq)
2373 {
2374 	struct sk_buff_head list;
2375 
2376 	__skb_queue_head_init(&list);
2377 	if (!tipc_link_build_bc_proto_msg(l->bc_rcvlink, false, 0, &list))
2378 		return;
2379 	msg_set_bc_ack_invalid(buf_msg(skb_peek(&list)), true);
2380 	tipc_link_xmit(l, &list, xmitq);
2381 }
2382 
2383 /* tipc_link_bc_init_rcv - receive initial broadcast synch data from peer
2384  */
2385 void tipc_link_bc_init_rcv(struct tipc_link *l, struct tipc_msg *hdr)
2386 {
2387 	int mtyp = msg_type(hdr);
2388 	u16 peers_snd_nxt = msg_bc_snd_nxt(hdr);
2389 
2390 	if (link_is_up(l))
2391 		return;
2392 
2393 	if (msg_user(hdr) == BCAST_PROTOCOL) {
2394 		l->rcv_nxt = peers_snd_nxt;
2395 		l->state = LINK_ESTABLISHED;
2396 		return;
2397 	}
2398 
2399 	if (l->peer_caps & TIPC_BCAST_SYNCH)
2400 		return;
2401 
2402 	if (msg_peer_node_is_up(hdr))
2403 		return;
2404 
2405 	/* Compatibility: accept older, less safe initial synch data */
2406 	if ((mtyp == RESET_MSG) || (mtyp == ACTIVATE_MSG))
2407 		l->rcv_nxt = peers_snd_nxt;
2408 }
2409 
2410 /* tipc_link_bc_sync_rcv - update rcv link according to peer's send state
2411  */
2412 int tipc_link_bc_sync_rcv(struct tipc_link *l, struct tipc_msg *hdr,
2413 			  struct sk_buff_head *xmitq)
2414 {
2415 	u16 peers_snd_nxt = msg_bc_snd_nxt(hdr);
2416 	int rc = 0;
2417 
2418 	if (!link_is_up(l))
2419 		return rc;
2420 
2421 	if (!msg_peer_node_is_up(hdr))
2422 		return rc;
2423 
2424 	/* Open when peer acknowledges our bcast init msg (pkt #1) */
2425 	if (msg_ack(hdr))
2426 		l->bc_peer_is_up = true;
2427 
2428 	if (!l->bc_peer_is_up)
2429 		return rc;
2430 
2431 	/* Ignore if peers_snd_nxt goes beyond receive window */
2432 	if (more(peers_snd_nxt, l->rcv_nxt + l->window))
2433 		return rc;
2434 
2435 	l->snd_nxt = peers_snd_nxt;
2436 	if (link_bc_rcv_gap(l))
2437 		rc |= TIPC_LINK_SND_STATE;
2438 
2439 	/* Return now if sender supports nack via STATE messages */
2440 	if (l->peer_caps & TIPC_BCAST_STATE_NACK)
2441 		return rc;
2442 
2443 	/* Otherwise, be backwards compatible */
2444 
2445 	if (!more(peers_snd_nxt, l->rcv_nxt)) {
2446 		l->nack_state = BC_NACK_SND_CONDITIONAL;
2447 		return 0;
2448 	}
2449 
2450 	/* Don't NACK if one was recently sent or peeked */
2451 	if (l->nack_state == BC_NACK_SND_SUPPRESS) {
2452 		l->nack_state = BC_NACK_SND_UNCONDITIONAL;
2453 		return 0;
2454 	}
2455 
2456 	/* Conditionally delay NACK sending until next synch rcv */
2457 	if (l->nack_state == BC_NACK_SND_CONDITIONAL) {
2458 		l->nack_state = BC_NACK_SND_UNCONDITIONAL;
2459 		if ((peers_snd_nxt - l->rcv_nxt) < TIPC_MIN_LINK_WIN)
2460 			return 0;
2461 	}
2462 
2463 	/* Send NACK now but suppress next one */
2464 	tipc_link_build_bc_proto_msg(l, true, peers_snd_nxt, xmitq);
2465 	l->nack_state = BC_NACK_SND_SUPPRESS;
2466 	return 0;
2467 }
2468 
2469 int tipc_link_bc_ack_rcv(struct tipc_link *r, u16 acked, u16 gap,
2470 			 struct tipc_gap_ack_blks *ga,
2471 			 struct sk_buff_head *xmitq,
2472 			 struct sk_buff_head *retrq)
2473 {
2474 	struct tipc_link *l = r->bc_sndlink;
2475 	bool unused = false;
2476 	int rc = 0;
2477 
2478 	if (!link_is_up(r) || !r->bc_peer_is_up)
2479 		return 0;
2480 
2481 	if (gap) {
2482 		l->stats.recv_nacks++;
2483 		r->stats.recv_nacks++;
2484 	}
2485 
2486 	if (less(acked, r->acked) || (acked == r->acked && !gap && !ga))
2487 		return 0;
2488 
2489 	trace_tipc_link_bc_ack(r, acked, gap, &l->transmq);
2490 	tipc_link_advance_transmq(l, r, acked, gap, ga, retrq, &unused, &rc);
2491 
2492 	tipc_link_advance_backlog(l, xmitq);
2493 	if (unlikely(!skb_queue_empty(&l->wakeupq)))
2494 		link_prepare_wakeup(l);
2495 
2496 	return rc;
2497 }
2498 
2499 /* tipc_link_bc_nack_rcv(): receive broadcast nack message
2500  * This function is here for backwards compatibility, since
2501  * no BCAST_PROTOCOL/STATE messages occur from TIPC v2.5.
2502  */
2503 int tipc_link_bc_nack_rcv(struct tipc_link *l, struct sk_buff *skb,
2504 			  struct sk_buff_head *xmitq)
2505 {
2506 	struct tipc_msg *hdr = buf_msg(skb);
2507 	u32 dnode = msg_destnode(hdr);
2508 	int mtyp = msg_type(hdr);
2509 	u16 acked = msg_bcast_ack(hdr);
2510 	u16 from = acked + 1;
2511 	u16 to = msg_bcgap_to(hdr);
2512 	u16 peers_snd_nxt = to + 1;
2513 	int rc = 0;
2514 
2515 	kfree_skb(skb);
2516 
2517 	if (!tipc_link_is_up(l) || !l->bc_peer_is_up)
2518 		return 0;
2519 
2520 	if (mtyp != STATE_MSG)
2521 		return 0;
2522 
2523 	if (dnode == tipc_own_addr(l->net)) {
2524 		rc = tipc_link_bc_ack_rcv(l, acked, to - acked, NULL, xmitq,
2525 					  xmitq);
2526 		l->stats.recv_nacks++;
2527 		return rc;
2528 	}
2529 
2530 	/* Msg for other node => suppress own NACK at next sync if applicable */
2531 	if (more(peers_snd_nxt, l->rcv_nxt) && !less(l->rcv_nxt, from))
2532 		l->nack_state = BC_NACK_SND_SUPPRESS;
2533 
2534 	return 0;
2535 }
2536 
2537 void tipc_link_set_queue_limits(struct tipc_link *l, u32 min_win, u32 max_win)
2538 {
2539 	int max_bulk = TIPC_MAX_PUBL / (l->mtu / ITEM_SIZE);
2540 
2541 	l->min_win = min_win;
2542 	l->ssthresh = max_win;
2543 	l->max_win = max_win;
2544 	l->window = min_win;
2545 	l->backlog[TIPC_LOW_IMPORTANCE].limit      = min_win * 2;
2546 	l->backlog[TIPC_MEDIUM_IMPORTANCE].limit   = min_win * 4;
2547 	l->backlog[TIPC_HIGH_IMPORTANCE].limit     = min_win * 6;
2548 	l->backlog[TIPC_CRITICAL_IMPORTANCE].limit = min_win * 8;
2549 	l->backlog[TIPC_SYSTEM_IMPORTANCE].limit   = max_bulk;
2550 }
2551 
2552 /**
2553  * tipc_link_reset_stats - reset link statistics
2554  * @l: pointer to link
2555  */
2556 void tipc_link_reset_stats(struct tipc_link *l)
2557 {
2558 	memset(&l->stats, 0, sizeof(l->stats));
2559 }
2560 
2561 static void link_print(struct tipc_link *l, const char *str)
2562 {
2563 	struct sk_buff *hskb = skb_peek(&l->transmq);
2564 	u16 head = hskb ? msg_seqno(buf_msg(hskb)) : l->snd_nxt - 1;
2565 	u16 tail = l->snd_nxt - 1;
2566 
2567 	pr_info("%s Link <%s> state %x\n", str, l->name, l->state);
2568 	pr_info("XMTQ: %u [%u-%u], BKLGQ: %u, SNDNX: %u, RCVNX: %u\n",
2569 		skb_queue_len(&l->transmq), head, tail,
2570 		skb_queue_len(&l->backlogq), l->snd_nxt, l->rcv_nxt);
2571 }
2572 
2573 /* Parse and validate nested (link) properties valid for media, bearer and link
2574  */
2575 int tipc_nl_parse_link_prop(struct nlattr *prop, struct nlattr *props[])
2576 {
2577 	int err;
2578 
2579 	err = nla_parse_nested_deprecated(props, TIPC_NLA_PROP_MAX, prop,
2580 					  tipc_nl_prop_policy, NULL);
2581 	if (err)
2582 		return err;
2583 
2584 	if (props[TIPC_NLA_PROP_PRIO]) {
2585 		u32 prio;
2586 
2587 		prio = nla_get_u32(props[TIPC_NLA_PROP_PRIO]);
2588 		if (prio > TIPC_MAX_LINK_PRI)
2589 			return -EINVAL;
2590 	}
2591 
2592 	if (props[TIPC_NLA_PROP_TOL]) {
2593 		u32 tol;
2594 
2595 		tol = nla_get_u32(props[TIPC_NLA_PROP_TOL]);
2596 		if ((tol < TIPC_MIN_LINK_TOL) || (tol > TIPC_MAX_LINK_TOL))
2597 			return -EINVAL;
2598 	}
2599 
2600 	if (props[TIPC_NLA_PROP_WIN]) {
2601 		u32 max_win;
2602 
2603 		max_win = nla_get_u32(props[TIPC_NLA_PROP_WIN]);
2604 		if (max_win < TIPC_DEF_LINK_WIN || max_win > TIPC_MAX_LINK_WIN)
2605 			return -EINVAL;
2606 	}
2607 
2608 	return 0;
2609 }
2610 
2611 static int __tipc_nl_add_stats(struct sk_buff *skb, struct tipc_stats *s)
2612 {
2613 	int i;
2614 	struct nlattr *stats;
2615 
2616 	struct nla_map {
2617 		u32 key;
2618 		u32 val;
2619 	};
2620 
2621 	struct nla_map map[] = {
2622 		{TIPC_NLA_STATS_RX_INFO, 0},
2623 		{TIPC_NLA_STATS_RX_FRAGMENTS, s->recv_fragments},
2624 		{TIPC_NLA_STATS_RX_FRAGMENTED, s->recv_fragmented},
2625 		{TIPC_NLA_STATS_RX_BUNDLES, s->recv_bundles},
2626 		{TIPC_NLA_STATS_RX_BUNDLED, s->recv_bundled},
2627 		{TIPC_NLA_STATS_TX_INFO, 0},
2628 		{TIPC_NLA_STATS_TX_FRAGMENTS, s->sent_fragments},
2629 		{TIPC_NLA_STATS_TX_FRAGMENTED, s->sent_fragmented},
2630 		{TIPC_NLA_STATS_TX_BUNDLES, s->sent_bundles},
2631 		{TIPC_NLA_STATS_TX_BUNDLED, s->sent_bundled},
2632 		{TIPC_NLA_STATS_MSG_PROF_TOT, (s->msg_length_counts) ?
2633 			s->msg_length_counts : 1},
2634 		{TIPC_NLA_STATS_MSG_LEN_CNT, s->msg_length_counts},
2635 		{TIPC_NLA_STATS_MSG_LEN_TOT, s->msg_lengths_total},
2636 		{TIPC_NLA_STATS_MSG_LEN_P0, s->msg_length_profile[0]},
2637 		{TIPC_NLA_STATS_MSG_LEN_P1, s->msg_length_profile[1]},
2638 		{TIPC_NLA_STATS_MSG_LEN_P2, s->msg_length_profile[2]},
2639 		{TIPC_NLA_STATS_MSG_LEN_P3, s->msg_length_profile[3]},
2640 		{TIPC_NLA_STATS_MSG_LEN_P4, s->msg_length_profile[4]},
2641 		{TIPC_NLA_STATS_MSG_LEN_P5, s->msg_length_profile[5]},
2642 		{TIPC_NLA_STATS_MSG_LEN_P6, s->msg_length_profile[6]},
2643 		{TIPC_NLA_STATS_RX_STATES, s->recv_states},
2644 		{TIPC_NLA_STATS_RX_PROBES, s->recv_probes},
2645 		{TIPC_NLA_STATS_RX_NACKS, s->recv_nacks},
2646 		{TIPC_NLA_STATS_RX_DEFERRED, s->deferred_recv},
2647 		{TIPC_NLA_STATS_TX_STATES, s->sent_states},
2648 		{TIPC_NLA_STATS_TX_PROBES, s->sent_probes},
2649 		{TIPC_NLA_STATS_TX_NACKS, s->sent_nacks},
2650 		{TIPC_NLA_STATS_TX_ACKS, s->sent_acks},
2651 		{TIPC_NLA_STATS_RETRANSMITTED, s->retransmitted},
2652 		{TIPC_NLA_STATS_DUPLICATES, s->duplicates},
2653 		{TIPC_NLA_STATS_LINK_CONGS, s->link_congs},
2654 		{TIPC_NLA_STATS_MAX_QUEUE, s->max_queue_sz},
2655 		{TIPC_NLA_STATS_AVG_QUEUE, s->queue_sz_counts ?
2656 			(s->accu_queue_sz / s->queue_sz_counts) : 0}
2657 	};
2658 
2659 	stats = nla_nest_start_noflag(skb, TIPC_NLA_LINK_STATS);
2660 	if (!stats)
2661 		return -EMSGSIZE;
2662 
2663 	for (i = 0; i <  ARRAY_SIZE(map); i++)
2664 		if (nla_put_u32(skb, map[i].key, map[i].val))
2665 			goto msg_full;
2666 
2667 	nla_nest_end(skb, stats);
2668 
2669 	return 0;
2670 msg_full:
2671 	nla_nest_cancel(skb, stats);
2672 
2673 	return -EMSGSIZE;
2674 }
2675 
2676 /* Caller should hold appropriate locks to protect the link */
2677 int __tipc_nl_add_link(struct net *net, struct tipc_nl_msg *msg,
2678 		       struct tipc_link *link, int nlflags)
2679 {
2680 	u32 self = tipc_own_addr(net);
2681 	struct nlattr *attrs;
2682 	struct nlattr *prop;
2683 	void *hdr;
2684 	int err;
2685 
2686 	hdr = genlmsg_put(msg->skb, msg->portid, msg->seq, &tipc_genl_family,
2687 			  nlflags, TIPC_NL_LINK_GET);
2688 	if (!hdr)
2689 		return -EMSGSIZE;
2690 
2691 	attrs = nla_nest_start_noflag(msg->skb, TIPC_NLA_LINK);
2692 	if (!attrs)
2693 		goto msg_full;
2694 
2695 	if (nla_put_string(msg->skb, TIPC_NLA_LINK_NAME, link->name))
2696 		goto attr_msg_full;
2697 	if (nla_put_u32(msg->skb, TIPC_NLA_LINK_DEST, tipc_cluster_mask(self)))
2698 		goto attr_msg_full;
2699 	if (nla_put_u32(msg->skb, TIPC_NLA_LINK_MTU, link->mtu))
2700 		goto attr_msg_full;
2701 	if (nla_put_u32(msg->skb, TIPC_NLA_LINK_RX, link->stats.recv_pkts))
2702 		goto attr_msg_full;
2703 	if (nla_put_u32(msg->skb, TIPC_NLA_LINK_TX, link->stats.sent_pkts))
2704 		goto attr_msg_full;
2705 
2706 	if (tipc_link_is_up(link))
2707 		if (nla_put_flag(msg->skb, TIPC_NLA_LINK_UP))
2708 			goto attr_msg_full;
2709 	if (link->active)
2710 		if (nla_put_flag(msg->skb, TIPC_NLA_LINK_ACTIVE))
2711 			goto attr_msg_full;
2712 
2713 	prop = nla_nest_start_noflag(msg->skb, TIPC_NLA_LINK_PROP);
2714 	if (!prop)
2715 		goto attr_msg_full;
2716 	if (nla_put_u32(msg->skb, TIPC_NLA_PROP_PRIO, link->priority))
2717 		goto prop_msg_full;
2718 	if (nla_put_u32(msg->skb, TIPC_NLA_PROP_TOL, link->tolerance))
2719 		goto prop_msg_full;
2720 	if (nla_put_u32(msg->skb, TIPC_NLA_PROP_WIN,
2721 			link->window))
2722 		goto prop_msg_full;
2723 	if (nla_put_u32(msg->skb, TIPC_NLA_PROP_PRIO, link->priority))
2724 		goto prop_msg_full;
2725 	nla_nest_end(msg->skb, prop);
2726 
2727 	err = __tipc_nl_add_stats(msg->skb, &link->stats);
2728 	if (err)
2729 		goto attr_msg_full;
2730 
2731 	nla_nest_end(msg->skb, attrs);
2732 	genlmsg_end(msg->skb, hdr);
2733 
2734 	return 0;
2735 
2736 prop_msg_full:
2737 	nla_nest_cancel(msg->skb, prop);
2738 attr_msg_full:
2739 	nla_nest_cancel(msg->skb, attrs);
2740 msg_full:
2741 	genlmsg_cancel(msg->skb, hdr);
2742 
2743 	return -EMSGSIZE;
2744 }
2745 
2746 static int __tipc_nl_add_bc_link_stat(struct sk_buff *skb,
2747 				      struct tipc_stats *stats)
2748 {
2749 	int i;
2750 	struct nlattr *nest;
2751 
2752 	struct nla_map {
2753 		__u32 key;
2754 		__u32 val;
2755 	};
2756 
2757 	struct nla_map map[] = {
2758 		{TIPC_NLA_STATS_RX_INFO, stats->recv_pkts},
2759 		{TIPC_NLA_STATS_RX_FRAGMENTS, stats->recv_fragments},
2760 		{TIPC_NLA_STATS_RX_FRAGMENTED, stats->recv_fragmented},
2761 		{TIPC_NLA_STATS_RX_BUNDLES, stats->recv_bundles},
2762 		{TIPC_NLA_STATS_RX_BUNDLED, stats->recv_bundled},
2763 		{TIPC_NLA_STATS_TX_INFO, stats->sent_pkts},
2764 		{TIPC_NLA_STATS_TX_FRAGMENTS, stats->sent_fragments},
2765 		{TIPC_NLA_STATS_TX_FRAGMENTED, stats->sent_fragmented},
2766 		{TIPC_NLA_STATS_TX_BUNDLES, stats->sent_bundles},
2767 		{TIPC_NLA_STATS_TX_BUNDLED, stats->sent_bundled},
2768 		{TIPC_NLA_STATS_RX_NACKS, stats->recv_nacks},
2769 		{TIPC_NLA_STATS_RX_DEFERRED, stats->deferred_recv},
2770 		{TIPC_NLA_STATS_TX_NACKS, stats->sent_nacks},
2771 		{TIPC_NLA_STATS_TX_ACKS, stats->sent_acks},
2772 		{TIPC_NLA_STATS_RETRANSMITTED, stats->retransmitted},
2773 		{TIPC_NLA_STATS_DUPLICATES, stats->duplicates},
2774 		{TIPC_NLA_STATS_LINK_CONGS, stats->link_congs},
2775 		{TIPC_NLA_STATS_MAX_QUEUE, stats->max_queue_sz},
2776 		{TIPC_NLA_STATS_AVG_QUEUE, stats->queue_sz_counts ?
2777 			(stats->accu_queue_sz / stats->queue_sz_counts) : 0}
2778 	};
2779 
2780 	nest = nla_nest_start_noflag(skb, TIPC_NLA_LINK_STATS);
2781 	if (!nest)
2782 		return -EMSGSIZE;
2783 
2784 	for (i = 0; i <  ARRAY_SIZE(map); i++)
2785 		if (nla_put_u32(skb, map[i].key, map[i].val))
2786 			goto msg_full;
2787 
2788 	nla_nest_end(skb, nest);
2789 
2790 	return 0;
2791 msg_full:
2792 	nla_nest_cancel(skb, nest);
2793 
2794 	return -EMSGSIZE;
2795 }
2796 
2797 int tipc_nl_add_bc_link(struct net *net, struct tipc_nl_msg *msg,
2798 			struct tipc_link *bcl)
2799 {
2800 	int err;
2801 	void *hdr;
2802 	struct nlattr *attrs;
2803 	struct nlattr *prop;
2804 	u32 bc_mode = tipc_bcast_get_mode(net);
2805 	u32 bc_ratio = tipc_bcast_get_broadcast_ratio(net);
2806 
2807 	if (!bcl)
2808 		return 0;
2809 
2810 	tipc_bcast_lock(net);
2811 
2812 	hdr = genlmsg_put(msg->skb, msg->portid, msg->seq, &tipc_genl_family,
2813 			  NLM_F_MULTI, TIPC_NL_LINK_GET);
2814 	if (!hdr) {
2815 		tipc_bcast_unlock(net);
2816 		return -EMSGSIZE;
2817 	}
2818 
2819 	attrs = nla_nest_start_noflag(msg->skb, TIPC_NLA_LINK);
2820 	if (!attrs)
2821 		goto msg_full;
2822 
2823 	/* The broadcast link is always up */
2824 	if (nla_put_flag(msg->skb, TIPC_NLA_LINK_UP))
2825 		goto attr_msg_full;
2826 
2827 	if (nla_put_flag(msg->skb, TIPC_NLA_LINK_BROADCAST))
2828 		goto attr_msg_full;
2829 	if (nla_put_string(msg->skb, TIPC_NLA_LINK_NAME, bcl->name))
2830 		goto attr_msg_full;
2831 	if (nla_put_u32(msg->skb, TIPC_NLA_LINK_RX, 0))
2832 		goto attr_msg_full;
2833 	if (nla_put_u32(msg->skb, TIPC_NLA_LINK_TX, 0))
2834 		goto attr_msg_full;
2835 
2836 	prop = nla_nest_start_noflag(msg->skb, TIPC_NLA_LINK_PROP);
2837 	if (!prop)
2838 		goto attr_msg_full;
2839 	if (nla_put_u32(msg->skb, TIPC_NLA_PROP_WIN, bcl->max_win))
2840 		goto prop_msg_full;
2841 	if (nla_put_u32(msg->skb, TIPC_NLA_PROP_BROADCAST, bc_mode))
2842 		goto prop_msg_full;
2843 	if (bc_mode & BCLINK_MODE_SEL)
2844 		if (nla_put_u32(msg->skb, TIPC_NLA_PROP_BROADCAST_RATIO,
2845 				bc_ratio))
2846 			goto prop_msg_full;
2847 	nla_nest_end(msg->skb, prop);
2848 
2849 	err = __tipc_nl_add_bc_link_stat(msg->skb, &bcl->stats);
2850 	if (err)
2851 		goto attr_msg_full;
2852 
2853 	tipc_bcast_unlock(net);
2854 	nla_nest_end(msg->skb, attrs);
2855 	genlmsg_end(msg->skb, hdr);
2856 
2857 	return 0;
2858 
2859 prop_msg_full:
2860 	nla_nest_cancel(msg->skb, prop);
2861 attr_msg_full:
2862 	nla_nest_cancel(msg->skb, attrs);
2863 msg_full:
2864 	tipc_bcast_unlock(net);
2865 	genlmsg_cancel(msg->skb, hdr);
2866 
2867 	return -EMSGSIZE;
2868 }
2869 
2870 void tipc_link_set_tolerance(struct tipc_link *l, u32 tol,
2871 			     struct sk_buff_head *xmitq)
2872 {
2873 	l->tolerance = tol;
2874 	if (l->bc_rcvlink)
2875 		l->bc_rcvlink->tolerance = tol;
2876 	if (link_is_up(l))
2877 		tipc_link_build_proto_msg(l, STATE_MSG, 0, 0, 0, tol, 0, xmitq);
2878 }
2879 
2880 void tipc_link_set_prio(struct tipc_link *l, u32 prio,
2881 			struct sk_buff_head *xmitq)
2882 {
2883 	l->priority = prio;
2884 	tipc_link_build_proto_msg(l, STATE_MSG, 0, 0, 0, 0, prio, xmitq);
2885 }
2886 
2887 void tipc_link_set_abort_limit(struct tipc_link *l, u32 limit)
2888 {
2889 	l->abort_limit = limit;
2890 }
2891 
2892 /**
2893  * tipc_link_dump - dump TIPC link data
2894  * @l: tipc link to be dumped
2895  * @dqueues: bitmask to decide if any link queue to be dumped?
2896  *           - TIPC_DUMP_NONE: don't dump link queues
2897  *           - TIPC_DUMP_TRANSMQ: dump link transmq queue
2898  *           - TIPC_DUMP_BACKLOGQ: dump link backlog queue
2899  *           - TIPC_DUMP_DEFERDQ: dump link deferd queue
2900  *           - TIPC_DUMP_INPUTQ: dump link input queue
2901  *           - TIPC_DUMP_WAKEUP: dump link wakeup queue
2902  *           - TIPC_DUMP_ALL: dump all the link queues above
2903  * @buf: returned buffer of dump data in format
2904  */
2905 int tipc_link_dump(struct tipc_link *l, u16 dqueues, char *buf)
2906 {
2907 	int i = 0;
2908 	size_t sz = (dqueues) ? LINK_LMAX : LINK_LMIN;
2909 	struct sk_buff_head *list;
2910 	struct sk_buff *hskb, *tskb;
2911 	u32 len;
2912 
2913 	if (!l) {
2914 		i += scnprintf(buf, sz, "link data: (null)\n");
2915 		return i;
2916 	}
2917 
2918 	i += scnprintf(buf, sz, "link data: %x", l->addr);
2919 	i += scnprintf(buf + i, sz - i, " %x", l->state);
2920 	i += scnprintf(buf + i, sz - i, " %u", l->in_session);
2921 	i += scnprintf(buf + i, sz - i, " %u", l->session);
2922 	i += scnprintf(buf + i, sz - i, " %u", l->peer_session);
2923 	i += scnprintf(buf + i, sz - i, " %u", l->snd_nxt);
2924 	i += scnprintf(buf + i, sz - i, " %u", l->rcv_nxt);
2925 	i += scnprintf(buf + i, sz - i, " %u", l->snd_nxt_state);
2926 	i += scnprintf(buf + i, sz - i, " %u", l->rcv_nxt_state);
2927 	i += scnprintf(buf + i, sz - i, " %x", l->peer_caps);
2928 	i += scnprintf(buf + i, sz - i, " %u", l->silent_intv_cnt);
2929 	i += scnprintf(buf + i, sz - i, " %u", l->rst_cnt);
2930 	i += scnprintf(buf + i, sz - i, " %u", 0);
2931 	i += scnprintf(buf + i, sz - i, " %u", 0);
2932 	i += scnprintf(buf + i, sz - i, " %u", l->acked);
2933 
2934 	list = &l->transmq;
2935 	len = skb_queue_len(list);
2936 	hskb = skb_peek(list);
2937 	tskb = skb_peek_tail(list);
2938 	i += scnprintf(buf + i, sz - i, " | %u %u %u", len,
2939 		       (hskb) ? msg_seqno(buf_msg(hskb)) : 0,
2940 		       (tskb) ? msg_seqno(buf_msg(tskb)) : 0);
2941 
2942 	list = &l->deferdq;
2943 	len = skb_queue_len(list);
2944 	hskb = skb_peek(list);
2945 	tskb = skb_peek_tail(list);
2946 	i += scnprintf(buf + i, sz - i, " | %u %u %u", len,
2947 		       (hskb) ? msg_seqno(buf_msg(hskb)) : 0,
2948 		       (tskb) ? msg_seqno(buf_msg(tskb)) : 0);
2949 
2950 	list = &l->backlogq;
2951 	len = skb_queue_len(list);
2952 	hskb = skb_peek(list);
2953 	tskb = skb_peek_tail(list);
2954 	i += scnprintf(buf + i, sz - i, " | %u %u %u", len,
2955 		       (hskb) ? msg_seqno(buf_msg(hskb)) : 0,
2956 		       (tskb) ? msg_seqno(buf_msg(tskb)) : 0);
2957 
2958 	list = l->inputq;
2959 	len = skb_queue_len(list);
2960 	hskb = skb_peek(list);
2961 	tskb = skb_peek_tail(list);
2962 	i += scnprintf(buf + i, sz - i, " | %u %u %u\n", len,
2963 		       (hskb) ? msg_seqno(buf_msg(hskb)) : 0,
2964 		       (tskb) ? msg_seqno(buf_msg(tskb)) : 0);
2965 
2966 	if (dqueues & TIPC_DUMP_TRANSMQ) {
2967 		i += scnprintf(buf + i, sz - i, "transmq: ");
2968 		i += tipc_list_dump(&l->transmq, false, buf + i);
2969 	}
2970 	if (dqueues & TIPC_DUMP_BACKLOGQ) {
2971 		i += scnprintf(buf + i, sz - i,
2972 			       "backlogq: <%u %u %u %u %u>, ",
2973 			       l->backlog[TIPC_LOW_IMPORTANCE].len,
2974 			       l->backlog[TIPC_MEDIUM_IMPORTANCE].len,
2975 			       l->backlog[TIPC_HIGH_IMPORTANCE].len,
2976 			       l->backlog[TIPC_CRITICAL_IMPORTANCE].len,
2977 			       l->backlog[TIPC_SYSTEM_IMPORTANCE].len);
2978 		i += tipc_list_dump(&l->backlogq, false, buf + i);
2979 	}
2980 	if (dqueues & TIPC_DUMP_DEFERDQ) {
2981 		i += scnprintf(buf + i, sz - i, "deferdq: ");
2982 		i += tipc_list_dump(&l->deferdq, false, buf + i);
2983 	}
2984 	if (dqueues & TIPC_DUMP_INPUTQ) {
2985 		i += scnprintf(buf + i, sz - i, "inputq: ");
2986 		i += tipc_list_dump(l->inputq, false, buf + i);
2987 	}
2988 	if (dqueues & TIPC_DUMP_WAKEUP) {
2989 		i += scnprintf(buf + i, sz - i, "wakeup: ");
2990 		i += tipc_list_dump(&l->wakeupq, false, buf + i);
2991 	}
2992 
2993 	return i;
2994 }
2995