xref: /linux/net/tipc/link.c (revision b77e0ce62d63a761ffb7f7245a215a49f5921c2f)
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  * @media_addr: media address to use when sending messages over link
86  * @timer: link timer
87  * @net: pointer to namespace struct
88  * @refcnt: reference counter for permanent references (owner node & timer)
89  * @peer_session: link session # being used by peer end of link
90  * @peer_bearer_id: bearer id used by link's peer endpoint
91  * @bearer_id: local bearer id used by link
92  * @tolerance: minimum link continuity loss needed to reset link [in ms]
93  * @abort_limit: # of unacknowledged continuity probes needed to reset link
94  * @state: current state of link FSM
95  * @peer_caps: bitmap describing capabilities of peer node
96  * @silent_intv_cnt: # of timer intervals without any reception from peer
97  * @proto_msg: template for control messages generated by link
98  * @pmsg: convenience pointer to "proto_msg" field
99  * @priority: current link priority
100  * @net_plane: current link network plane ('A' through 'H')
101  * @mon_state: cookie with information needed by link monitor
102  * @backlog_limit: backlog queue congestion thresholds (indexed by importance)
103  * @exp_msg_count: # of tunnelled messages expected during link changeover
104  * @reset_rcv_checkpt: seq # of last acknowledged message at time of link reset
105  * @mtu: current maximum packet size for this link
106  * @advertised_mtu: advertised own mtu when link is being established
107  * @transmitq: queue for sent, non-acked messages
108  * @backlogq: queue for messages waiting to be sent
109  * @snt_nxt: next sequence number to use for outbound messages
110  * @ackers: # of peers that needs to ack each packet before it can be released
111  * @acked: # last packet acked by a certain peer. Used for broadcast.
112  * @rcv_nxt: next sequence number to expect for inbound messages
113  * @deferred_queue: deferred queue saved OOS b'cast message received from node
114  * @unacked_window: # of inbound messages rx'd without ack'ing back to peer
115  * @inputq: buffer queue for messages to be delivered upwards
116  * @namedq: buffer queue for name table messages to be delivered upwards
117  * @next_out: ptr to first unsent outbound message in queue
118  * @wakeupq: linked list of wakeup msgs waiting for link congestion to abate
119  * @long_msg_seq_no: next identifier to use for outbound fragmented messages
120  * @reasm_buf: head of partially reassembled inbound message fragments
121  * @bc_rcvr: marks that this is a broadcast receiver link
122  * @stats: collects statistics regarding link activity
123  * @session: session to be used by link
124  * @snd_nxt_state: next send seq number
125  * @rcv_nxt_state: next rcv seq number
126  * @in_session: have received ACTIVATE_MSG from peer
127  * @active: link is active
128  * @if_name: associated interface name
129  * @rst_cnt: link reset counter
130  * @drop_point: seq number for failover handling (FIXME)
131  * @failover_reasm_skb: saved failover msg ptr (FIXME)
132  * @failover_deferdq: deferred message queue for failover processing (FIXME)
133  * @transmq: the link's transmit queue
134  * @backlog: link's backlog by priority (importance)
135  * @snd_nxt: next sequence number to be used
136  * @rcv_unacked: # messages read by user, but not yet acked back to peer
137  * @deferdq: deferred receive queue
138  * @window: sliding window size for congestion handling
139  * @min_win: minimal send window to be used by link
140  * @ssthresh: slow start threshold for congestion handling
141  * @max_win: maximal send window to be used by link
142  * @cong_acks: congestion acks for congestion avoidance (FIXME)
143  * @checkpoint: seq number for congestion window size handling
144  * @reasm_tnlmsg: fragmentation/reassembly area for tunnel protocol message
145  * @last_gap: last gap ack blocks for bcast (FIXME)
146  * @last_ga: ptr to gap ack blocks
147  * @bc_rcvlink: the peer specific link used for broadcast reception
148  * @bc_sndlink: the namespace global link used for broadcast sending
149  * @nack_state: bcast nack state
150  * @bc_peer_is_up: peer has acked the bcast init msg
151  */
152 struct tipc_link {
153 	u32 addr;
154 	char name[TIPC_MAX_LINK_NAME];
155 	struct net *net;
156 
157 	/* Management and link supervision data */
158 	u16 peer_session;
159 	u16 session;
160 	u16 snd_nxt_state;
161 	u16 rcv_nxt_state;
162 	u32 peer_bearer_id;
163 	u32 bearer_id;
164 	u32 tolerance;
165 	u32 abort_limit;
166 	u32 state;
167 	u16 peer_caps;
168 	bool in_session;
169 	bool active;
170 	u32 silent_intv_cnt;
171 	char if_name[TIPC_MAX_IF_NAME];
172 	u32 priority;
173 	char net_plane;
174 	struct tipc_mon_state mon_state;
175 	u16 rst_cnt;
176 
177 	/* Failover/synch */
178 	u16 drop_point;
179 	struct sk_buff *failover_reasm_skb;
180 	struct sk_buff_head failover_deferdq;
181 
182 	/* Max packet negotiation */
183 	u16 mtu;
184 	u16 advertised_mtu;
185 
186 	/* Sending */
187 	struct sk_buff_head transmq;
188 	struct sk_buff_head backlogq;
189 	struct {
190 		u16 len;
191 		u16 limit;
192 		struct sk_buff *target_bskb;
193 	} backlog[5];
194 	u16 snd_nxt;
195 
196 	/* Reception */
197 	u16 rcv_nxt;
198 	u32 rcv_unacked;
199 	struct sk_buff_head deferdq;
200 	struct sk_buff_head *inputq;
201 	struct sk_buff_head *namedq;
202 
203 	/* Congestion handling */
204 	struct sk_buff_head wakeupq;
205 	u16 window;
206 	u16 min_win;
207 	u16 ssthresh;
208 	u16 max_win;
209 	u16 cong_acks;
210 	u16 checkpoint;
211 
212 	/* Fragmentation/reassembly */
213 	struct sk_buff *reasm_buf;
214 	struct sk_buff *reasm_tnlmsg;
215 
216 	/* Broadcast */
217 	u16 ackers;
218 	u16 acked;
219 	u16 last_gap;
220 	struct tipc_gap_ack_blks *last_ga;
221 	struct tipc_link *bc_rcvlink;
222 	struct tipc_link *bc_sndlink;
223 	u8 nack_state;
224 	bool bc_peer_is_up;
225 
226 	/* Statistics */
227 	struct tipc_stats stats;
228 };
229 
230 /*
231  * Error message prefixes
232  */
233 static const char *link_co_err = "Link tunneling error, ";
234 static const char *link_rst_msg = "Resetting link ";
235 
236 /* Send states for broadcast NACKs
237  */
238 enum {
239 	BC_NACK_SND_CONDITIONAL,
240 	BC_NACK_SND_UNCONDITIONAL,
241 	BC_NACK_SND_SUPPRESS,
242 };
243 
244 #define TIPC_BC_RETR_LIM  (jiffies + msecs_to_jiffies(10))
245 #define TIPC_UC_RETR_TIME (jiffies + msecs_to_jiffies(1))
246 
247 /* Link FSM states:
248  */
249 enum {
250 	LINK_ESTABLISHED     = 0xe,
251 	LINK_ESTABLISHING    = 0xe  << 4,
252 	LINK_RESET           = 0x1  << 8,
253 	LINK_RESETTING       = 0x2  << 12,
254 	LINK_PEER_RESET      = 0xd  << 16,
255 	LINK_FAILINGOVER     = 0xf  << 20,
256 	LINK_SYNCHING        = 0xc  << 24
257 };
258 
259 /* Link FSM state checking routines
260  */
261 static int link_is_up(struct tipc_link *l)
262 {
263 	return l->state & (LINK_ESTABLISHED | LINK_SYNCHING);
264 }
265 
266 static int tipc_link_proto_rcv(struct tipc_link *l, struct sk_buff *skb,
267 			       struct sk_buff_head *xmitq);
268 static void tipc_link_build_proto_msg(struct tipc_link *l, int mtyp, bool probe,
269 				      bool probe_reply, u16 rcvgap,
270 				      int tolerance, int priority,
271 				      struct sk_buff_head *xmitq);
272 static void link_print(struct tipc_link *l, const char *str);
273 static int tipc_link_build_nack_msg(struct tipc_link *l,
274 				    struct sk_buff_head *xmitq);
275 static void tipc_link_build_bc_init_msg(struct tipc_link *l,
276 					struct sk_buff_head *xmitq);
277 static u8 __tipc_build_gap_ack_blks(struct tipc_gap_ack_blks *ga,
278 				    struct tipc_link *l, u8 start_index);
279 static u16 tipc_build_gap_ack_blks(struct tipc_link *l, struct tipc_msg *hdr);
280 static int tipc_link_advance_transmq(struct tipc_link *l, struct tipc_link *r,
281 				     u16 acked, u16 gap,
282 				     struct tipc_gap_ack_blks *ga,
283 				     struct sk_buff_head *xmitq,
284 				     bool *retransmitted, int *rc);
285 static void tipc_link_update_cwin(struct tipc_link *l, int released,
286 				  bool retransmitted);
287 /*
288  *  Simple non-static link routines (i.e. referenced outside this file)
289  */
290 bool tipc_link_is_up(struct tipc_link *l)
291 {
292 	return link_is_up(l);
293 }
294 
295 bool tipc_link_peer_is_down(struct tipc_link *l)
296 {
297 	return l->state == LINK_PEER_RESET;
298 }
299 
300 bool tipc_link_is_reset(struct tipc_link *l)
301 {
302 	return l->state & (LINK_RESET | LINK_FAILINGOVER | LINK_ESTABLISHING);
303 }
304 
305 bool tipc_link_is_establishing(struct tipc_link *l)
306 {
307 	return l->state == LINK_ESTABLISHING;
308 }
309 
310 bool tipc_link_is_synching(struct tipc_link *l)
311 {
312 	return l->state == LINK_SYNCHING;
313 }
314 
315 bool tipc_link_is_failingover(struct tipc_link *l)
316 {
317 	return l->state == LINK_FAILINGOVER;
318 }
319 
320 bool tipc_link_is_blocked(struct tipc_link *l)
321 {
322 	return l->state & (LINK_RESETTING | LINK_PEER_RESET | LINK_FAILINGOVER);
323 }
324 
325 static bool link_is_bc_sndlink(struct tipc_link *l)
326 {
327 	return !l->bc_sndlink;
328 }
329 
330 static bool link_is_bc_rcvlink(struct tipc_link *l)
331 {
332 	return ((l->bc_rcvlink == l) && !link_is_bc_sndlink(l));
333 }
334 
335 void tipc_link_set_active(struct tipc_link *l, bool active)
336 {
337 	l->active = active;
338 }
339 
340 u32 tipc_link_id(struct tipc_link *l)
341 {
342 	return l->peer_bearer_id << 16 | l->bearer_id;
343 }
344 
345 int tipc_link_min_win(struct tipc_link *l)
346 {
347 	return l->min_win;
348 }
349 
350 int tipc_link_max_win(struct tipc_link *l)
351 {
352 	return l->max_win;
353 }
354 
355 int tipc_link_prio(struct tipc_link *l)
356 {
357 	return l->priority;
358 }
359 
360 unsigned long tipc_link_tolerance(struct tipc_link *l)
361 {
362 	return l->tolerance;
363 }
364 
365 struct sk_buff_head *tipc_link_inputq(struct tipc_link *l)
366 {
367 	return l->inputq;
368 }
369 
370 char tipc_link_plane(struct tipc_link *l)
371 {
372 	return l->net_plane;
373 }
374 
375 void tipc_link_update_caps(struct tipc_link *l, u16 capabilities)
376 {
377 	l->peer_caps = capabilities;
378 }
379 
380 void tipc_link_add_bc_peer(struct tipc_link *snd_l,
381 			   struct tipc_link *uc_l,
382 			   struct sk_buff_head *xmitq)
383 {
384 	struct tipc_link *rcv_l = uc_l->bc_rcvlink;
385 
386 	snd_l->ackers++;
387 	rcv_l->acked = snd_l->snd_nxt - 1;
388 	snd_l->state = LINK_ESTABLISHED;
389 	tipc_link_build_bc_init_msg(uc_l, xmitq);
390 }
391 
392 void tipc_link_remove_bc_peer(struct tipc_link *snd_l,
393 			      struct tipc_link *rcv_l,
394 			      struct sk_buff_head *xmitq)
395 {
396 	u16 ack = snd_l->snd_nxt - 1;
397 
398 	snd_l->ackers--;
399 	rcv_l->bc_peer_is_up = true;
400 	rcv_l->state = LINK_ESTABLISHED;
401 	tipc_link_bc_ack_rcv(rcv_l, ack, 0, NULL, xmitq, NULL);
402 	trace_tipc_link_reset(rcv_l, TIPC_DUMP_ALL, "bclink removed!");
403 	tipc_link_reset(rcv_l);
404 	rcv_l->state = LINK_RESET;
405 	if (!snd_l->ackers) {
406 		trace_tipc_link_reset(snd_l, TIPC_DUMP_ALL, "zero ackers!");
407 		tipc_link_reset(snd_l);
408 		snd_l->state = LINK_RESET;
409 		__skb_queue_purge(xmitq);
410 	}
411 }
412 
413 int tipc_link_bc_peers(struct tipc_link *l)
414 {
415 	return l->ackers;
416 }
417 
418 static u16 link_bc_rcv_gap(struct tipc_link *l)
419 {
420 	struct sk_buff *skb = skb_peek(&l->deferdq);
421 	u16 gap = 0;
422 
423 	if (more(l->snd_nxt, l->rcv_nxt))
424 		gap = l->snd_nxt - l->rcv_nxt;
425 	if (skb)
426 		gap = buf_seqno(skb) - l->rcv_nxt;
427 	return gap;
428 }
429 
430 void tipc_link_set_mtu(struct tipc_link *l, int mtu)
431 {
432 	l->mtu = mtu;
433 }
434 
435 int tipc_link_mtu(struct tipc_link *l)
436 {
437 	return l->mtu;
438 }
439 
440 int tipc_link_mss(struct tipc_link *l)
441 {
442 #ifdef CONFIG_TIPC_CRYPTO
443 	return l->mtu - INT_H_SIZE - EMSG_OVERHEAD;
444 #else
445 	return l->mtu - INT_H_SIZE;
446 #endif
447 }
448 
449 u16 tipc_link_rcv_nxt(struct tipc_link *l)
450 {
451 	return l->rcv_nxt;
452 }
453 
454 u16 tipc_link_acked(struct tipc_link *l)
455 {
456 	return l->acked;
457 }
458 
459 char *tipc_link_name(struct tipc_link *l)
460 {
461 	return l->name;
462 }
463 
464 u32 tipc_link_state(struct tipc_link *l)
465 {
466 	return l->state;
467 }
468 
469 /**
470  * tipc_link_create - create a new link
471  * @net: pointer to associated network namespace
472  * @if_name: associated interface name
473  * @bearer_id: id (index) of associated bearer
474  * @tolerance: link tolerance to be used by link
475  * @net_plane: network plane (A,B,c..) this link belongs to
476  * @mtu: mtu to be advertised by link
477  * @priority: priority to be used by link
478  * @min_win: minimal send window to be used by link
479  * @max_win: maximal send window to be used by link
480  * @session: session to be used by link
481  * @peer: node id of peer node
482  * @peer_caps: bitmap describing peer node capabilities
483  * @bc_sndlink: the namespace global link used for broadcast sending
484  * @bc_rcvlink: the peer specific link used for broadcast reception
485  * @inputq: queue to put messages ready for delivery
486  * @namedq: queue to put binding table update messages ready for delivery
487  * @link: return value, pointer to put the created link
488  * @self: local unicast link id
489  * @peer_id: 128-bit ID of peer
490  *
491  * Return: true if link was created, otherwise false
492  */
493 bool tipc_link_create(struct net *net, char *if_name, int bearer_id,
494 		      int tolerance, char net_plane, u32 mtu, int priority,
495 		      u32 min_win, u32 max_win, u32 session, u32 self,
496 		      u32 peer, u8 *peer_id, u16 peer_caps,
497 		      struct tipc_link *bc_sndlink,
498 		      struct tipc_link *bc_rcvlink,
499 		      struct sk_buff_head *inputq,
500 		      struct sk_buff_head *namedq,
501 		      struct tipc_link **link)
502 {
503 	char peer_str[NODE_ID_STR_LEN] = {0,};
504 	char self_str[NODE_ID_STR_LEN] = {0,};
505 	struct tipc_link *l;
506 
507 	l = kzalloc(sizeof(*l), GFP_ATOMIC);
508 	if (!l)
509 		return false;
510 	*link = l;
511 	l->session = session;
512 
513 	/* Set link name for unicast links only */
514 	if (peer_id) {
515 		tipc_nodeid2string(self_str, tipc_own_id(net));
516 		if (strlen(self_str) > 16)
517 			sprintf(self_str, "%x", self);
518 		tipc_nodeid2string(peer_str, peer_id);
519 		if (strlen(peer_str) > 16)
520 			sprintf(peer_str, "%x", peer);
521 	}
522 	/* Peer i/f name will be completed by reset/activate message */
523 	snprintf(l->name, sizeof(l->name), "%s:%s-%s:unknown",
524 		 self_str, if_name, peer_str);
525 
526 	strcpy(l->if_name, if_name);
527 	l->addr = peer;
528 	l->peer_caps = peer_caps;
529 	l->net = net;
530 	l->in_session = false;
531 	l->bearer_id = bearer_id;
532 	l->tolerance = tolerance;
533 	if (bc_rcvlink)
534 		bc_rcvlink->tolerance = tolerance;
535 	l->net_plane = net_plane;
536 	l->advertised_mtu = mtu;
537 	l->mtu = mtu;
538 	l->priority = priority;
539 	tipc_link_set_queue_limits(l, min_win, max_win);
540 	l->ackers = 1;
541 	l->bc_sndlink = bc_sndlink;
542 	l->bc_rcvlink = bc_rcvlink;
543 	l->inputq = inputq;
544 	l->namedq = namedq;
545 	l->state = LINK_RESETTING;
546 	__skb_queue_head_init(&l->transmq);
547 	__skb_queue_head_init(&l->backlogq);
548 	__skb_queue_head_init(&l->deferdq);
549 	__skb_queue_head_init(&l->failover_deferdq);
550 	skb_queue_head_init(&l->wakeupq);
551 	skb_queue_head_init(l->inputq);
552 	return true;
553 }
554 
555 /**
556  * tipc_link_bc_create - create new link to be used for broadcast
557  * @net: pointer to associated network namespace
558  * @mtu: mtu to be used initially if no peers
559  * @min_win: minimal send window to be used by link
560  * @max_win: maximal send window to be used by link
561  * @inputq: queue to put messages ready for delivery
562  * @namedq: queue to put binding table update messages ready for delivery
563  * @link: return value, pointer to put the created link
564  * @ownnode: identity of own node
565  * @peer: node id of peer node
566  * @peer_id: 128-bit ID of peer
567  * @peer_caps: bitmap describing peer node capabilities
568  * @bc_sndlink: the namespace global link used for broadcast sending
569  *
570  * Return: true if link was created, otherwise false
571  */
572 bool tipc_link_bc_create(struct net *net, u32 ownnode, u32 peer, u8 *peer_id,
573 			 int mtu, u32 min_win, u32 max_win, u16 peer_caps,
574 			 struct sk_buff_head *inputq,
575 			 struct sk_buff_head *namedq,
576 			 struct tipc_link *bc_sndlink,
577 			 struct tipc_link **link)
578 {
579 	struct tipc_link *l;
580 
581 	if (!tipc_link_create(net, "", MAX_BEARERS, 0, 'Z', mtu, 0, min_win,
582 			      max_win, 0, ownnode, peer, NULL, peer_caps,
583 			      bc_sndlink, NULL, inputq, namedq, link))
584 		return false;
585 
586 	l = *link;
587 	if (peer_id) {
588 		char peer_str[NODE_ID_STR_LEN] = {0,};
589 
590 		tipc_nodeid2string(peer_str, peer_id);
591 		if (strlen(peer_str) > 16)
592 			sprintf(peer_str, "%x", peer);
593 		/* Broadcast receiver link name: "broadcast-link:<peer>" */
594 		snprintf(l->name, sizeof(l->name), "%s:%s", tipc_bclink_name,
595 			 peer_str);
596 	} else {
597 		strcpy(l->name, tipc_bclink_name);
598 	}
599 	trace_tipc_link_reset(l, TIPC_DUMP_ALL, "bclink created!");
600 	tipc_link_reset(l);
601 	l->state = LINK_RESET;
602 	l->ackers = 0;
603 	l->bc_rcvlink = l;
604 
605 	/* Broadcast send link is always up */
606 	if (link_is_bc_sndlink(l))
607 		l->state = LINK_ESTABLISHED;
608 
609 	/* Disable replicast if even a single peer doesn't support it */
610 	if (link_is_bc_rcvlink(l) && !(peer_caps & TIPC_BCAST_RCAST))
611 		tipc_bcast_toggle_rcast(net, false);
612 
613 	return true;
614 }
615 
616 /**
617  * tipc_link_fsm_evt - link finite state machine
618  * @l: pointer to link
619  * @evt: state machine event to be processed
620  */
621 int tipc_link_fsm_evt(struct tipc_link *l, int evt)
622 {
623 	int rc = 0;
624 	int old_state = l->state;
625 
626 	switch (l->state) {
627 	case LINK_RESETTING:
628 		switch (evt) {
629 		case LINK_PEER_RESET_EVT:
630 			l->state = LINK_PEER_RESET;
631 			break;
632 		case LINK_RESET_EVT:
633 			l->state = LINK_RESET;
634 			break;
635 		case LINK_FAILURE_EVT:
636 		case LINK_FAILOVER_BEGIN_EVT:
637 		case LINK_ESTABLISH_EVT:
638 		case LINK_FAILOVER_END_EVT:
639 		case LINK_SYNCH_BEGIN_EVT:
640 		case LINK_SYNCH_END_EVT:
641 		default:
642 			goto illegal_evt;
643 		}
644 		break;
645 	case LINK_RESET:
646 		switch (evt) {
647 		case LINK_PEER_RESET_EVT:
648 			l->state = LINK_ESTABLISHING;
649 			break;
650 		case LINK_FAILOVER_BEGIN_EVT:
651 			l->state = LINK_FAILINGOVER;
652 		case LINK_FAILURE_EVT:
653 		case LINK_RESET_EVT:
654 		case LINK_ESTABLISH_EVT:
655 		case LINK_FAILOVER_END_EVT:
656 			break;
657 		case LINK_SYNCH_BEGIN_EVT:
658 		case LINK_SYNCH_END_EVT:
659 		default:
660 			goto illegal_evt;
661 		}
662 		break;
663 	case LINK_PEER_RESET:
664 		switch (evt) {
665 		case LINK_RESET_EVT:
666 			l->state = LINK_ESTABLISHING;
667 			break;
668 		case LINK_PEER_RESET_EVT:
669 		case LINK_ESTABLISH_EVT:
670 		case LINK_FAILURE_EVT:
671 			break;
672 		case LINK_SYNCH_BEGIN_EVT:
673 		case LINK_SYNCH_END_EVT:
674 		case LINK_FAILOVER_BEGIN_EVT:
675 		case LINK_FAILOVER_END_EVT:
676 		default:
677 			goto illegal_evt;
678 		}
679 		break;
680 	case LINK_FAILINGOVER:
681 		switch (evt) {
682 		case LINK_FAILOVER_END_EVT:
683 			l->state = LINK_RESET;
684 			break;
685 		case LINK_PEER_RESET_EVT:
686 		case LINK_RESET_EVT:
687 		case LINK_ESTABLISH_EVT:
688 		case LINK_FAILURE_EVT:
689 			break;
690 		case LINK_FAILOVER_BEGIN_EVT:
691 		case LINK_SYNCH_BEGIN_EVT:
692 		case LINK_SYNCH_END_EVT:
693 		default:
694 			goto illegal_evt;
695 		}
696 		break;
697 	case LINK_ESTABLISHING:
698 		switch (evt) {
699 		case LINK_ESTABLISH_EVT:
700 			l->state = LINK_ESTABLISHED;
701 			break;
702 		case LINK_FAILOVER_BEGIN_EVT:
703 			l->state = LINK_FAILINGOVER;
704 			break;
705 		case LINK_RESET_EVT:
706 			l->state = LINK_RESET;
707 			break;
708 		case LINK_FAILURE_EVT:
709 		case LINK_PEER_RESET_EVT:
710 		case LINK_SYNCH_BEGIN_EVT:
711 		case LINK_FAILOVER_END_EVT:
712 			break;
713 		case LINK_SYNCH_END_EVT:
714 		default:
715 			goto illegal_evt;
716 		}
717 		break;
718 	case LINK_ESTABLISHED:
719 		switch (evt) {
720 		case LINK_PEER_RESET_EVT:
721 			l->state = LINK_PEER_RESET;
722 			rc |= TIPC_LINK_DOWN_EVT;
723 			break;
724 		case LINK_FAILURE_EVT:
725 			l->state = LINK_RESETTING;
726 			rc |= TIPC_LINK_DOWN_EVT;
727 			break;
728 		case LINK_RESET_EVT:
729 			l->state = LINK_RESET;
730 			break;
731 		case LINK_ESTABLISH_EVT:
732 		case LINK_SYNCH_END_EVT:
733 			break;
734 		case LINK_SYNCH_BEGIN_EVT:
735 			l->state = LINK_SYNCHING;
736 			break;
737 		case LINK_FAILOVER_BEGIN_EVT:
738 		case LINK_FAILOVER_END_EVT:
739 		default:
740 			goto illegal_evt;
741 		}
742 		break;
743 	case LINK_SYNCHING:
744 		switch (evt) {
745 		case LINK_PEER_RESET_EVT:
746 			l->state = LINK_PEER_RESET;
747 			rc |= TIPC_LINK_DOWN_EVT;
748 			break;
749 		case LINK_FAILURE_EVT:
750 			l->state = LINK_RESETTING;
751 			rc |= TIPC_LINK_DOWN_EVT;
752 			break;
753 		case LINK_RESET_EVT:
754 			l->state = LINK_RESET;
755 			break;
756 		case LINK_ESTABLISH_EVT:
757 		case LINK_SYNCH_BEGIN_EVT:
758 			break;
759 		case LINK_SYNCH_END_EVT:
760 			l->state = LINK_ESTABLISHED;
761 			break;
762 		case LINK_FAILOVER_BEGIN_EVT:
763 		case LINK_FAILOVER_END_EVT:
764 		default:
765 			goto illegal_evt;
766 		}
767 		break;
768 	default:
769 		pr_err("Unknown FSM state %x in %s\n", l->state, l->name);
770 	}
771 	trace_tipc_link_fsm(l->name, old_state, l->state, evt);
772 	return rc;
773 illegal_evt:
774 	pr_err("Illegal FSM event %x in state %x on link %s\n",
775 	       evt, l->state, l->name);
776 	trace_tipc_link_fsm(l->name, old_state, l->state, evt);
777 	return rc;
778 }
779 
780 /* link_profile_stats - update statistical profiling of traffic
781  */
782 static void link_profile_stats(struct tipc_link *l)
783 {
784 	struct sk_buff *skb;
785 	struct tipc_msg *msg;
786 	int length;
787 
788 	/* Update counters used in statistical profiling of send traffic */
789 	l->stats.accu_queue_sz += skb_queue_len(&l->transmq);
790 	l->stats.queue_sz_counts++;
791 
792 	skb = skb_peek(&l->transmq);
793 	if (!skb)
794 		return;
795 	msg = buf_msg(skb);
796 	length = msg_size(msg);
797 
798 	if (msg_user(msg) == MSG_FRAGMENTER) {
799 		if (msg_type(msg) != FIRST_FRAGMENT)
800 			return;
801 		length = msg_size(msg_inner_hdr(msg));
802 	}
803 	l->stats.msg_lengths_total += length;
804 	l->stats.msg_length_counts++;
805 	if (length <= 64)
806 		l->stats.msg_length_profile[0]++;
807 	else if (length <= 256)
808 		l->stats.msg_length_profile[1]++;
809 	else if (length <= 1024)
810 		l->stats.msg_length_profile[2]++;
811 	else if (length <= 4096)
812 		l->stats.msg_length_profile[3]++;
813 	else if (length <= 16384)
814 		l->stats.msg_length_profile[4]++;
815 	else if (length <= 32768)
816 		l->stats.msg_length_profile[5]++;
817 	else
818 		l->stats.msg_length_profile[6]++;
819 }
820 
821 /**
822  * tipc_link_too_silent - check if link is "too silent"
823  * @l: tipc link to be checked
824  *
825  * Return: true if the link 'silent_intv_cnt' is about to reach the
826  * 'abort_limit' value, otherwise false
827  */
828 bool tipc_link_too_silent(struct tipc_link *l)
829 {
830 	return (l->silent_intv_cnt + 2 > l->abort_limit);
831 }
832 
833 /* tipc_link_timeout - perform periodic task as instructed from node timeout
834  */
835 int tipc_link_timeout(struct tipc_link *l, struct sk_buff_head *xmitq)
836 {
837 	int mtyp = 0;
838 	int rc = 0;
839 	bool state = false;
840 	bool probe = false;
841 	bool setup = false;
842 	u16 bc_snt = l->bc_sndlink->snd_nxt - 1;
843 	u16 bc_acked = l->bc_rcvlink->acked;
844 	struct tipc_mon_state *mstate = &l->mon_state;
845 
846 	trace_tipc_link_timeout(l, TIPC_DUMP_NONE, " ");
847 	trace_tipc_link_too_silent(l, TIPC_DUMP_ALL, " ");
848 	switch (l->state) {
849 	case LINK_ESTABLISHED:
850 	case LINK_SYNCHING:
851 		mtyp = STATE_MSG;
852 		link_profile_stats(l);
853 		tipc_mon_get_state(l->net, l->addr, mstate, l->bearer_id);
854 		if (mstate->reset || (l->silent_intv_cnt > l->abort_limit))
855 			return tipc_link_fsm_evt(l, LINK_FAILURE_EVT);
856 		state = bc_acked != bc_snt;
857 		state |= l->bc_rcvlink->rcv_unacked;
858 		state |= l->rcv_unacked;
859 		state |= !skb_queue_empty(&l->transmq);
860 		probe = mstate->probing;
861 		probe |= l->silent_intv_cnt;
862 		if (probe || mstate->monitoring)
863 			l->silent_intv_cnt++;
864 		probe |= !skb_queue_empty(&l->deferdq);
865 		if (l->snd_nxt == l->checkpoint) {
866 			tipc_link_update_cwin(l, 0, 0);
867 			probe = true;
868 		}
869 		l->checkpoint = l->snd_nxt;
870 		break;
871 	case LINK_RESET:
872 		setup = l->rst_cnt++ <= 4;
873 		setup |= !(l->rst_cnt % 16);
874 		mtyp = RESET_MSG;
875 		break;
876 	case LINK_ESTABLISHING:
877 		setup = true;
878 		mtyp = ACTIVATE_MSG;
879 		break;
880 	case LINK_PEER_RESET:
881 	case LINK_RESETTING:
882 	case LINK_FAILINGOVER:
883 		break;
884 	default:
885 		break;
886 	}
887 
888 	if (state || probe || setup)
889 		tipc_link_build_proto_msg(l, mtyp, probe, 0, 0, 0, 0, xmitq);
890 
891 	return rc;
892 }
893 
894 /**
895  * link_schedule_user - schedule a message sender for wakeup after congestion
896  * @l: congested link
897  * @hdr: header of message that is being sent
898  * Create pseudo msg to send back to user when congestion abates
899  */
900 static int link_schedule_user(struct tipc_link *l, struct tipc_msg *hdr)
901 {
902 	u32 dnode = tipc_own_addr(l->net);
903 	u32 dport = msg_origport(hdr);
904 	struct sk_buff *skb;
905 
906 	/* Create and schedule wakeup pseudo message */
907 	skb = tipc_msg_create(SOCK_WAKEUP, 0, INT_H_SIZE, 0,
908 			      dnode, l->addr, dport, 0, 0);
909 	if (!skb)
910 		return -ENOBUFS;
911 	msg_set_dest_droppable(buf_msg(skb), true);
912 	TIPC_SKB_CB(skb)->chain_imp = msg_importance(hdr);
913 	skb_queue_tail(&l->wakeupq, skb);
914 	l->stats.link_congs++;
915 	trace_tipc_link_conges(l, TIPC_DUMP_ALL, "wakeup scheduled!");
916 	return -ELINKCONG;
917 }
918 
919 /**
920  * link_prepare_wakeup - prepare users for wakeup after congestion
921  * @l: congested link
922  * Wake up a number of waiting users, as permitted by available space
923  * in the send queue
924  */
925 static void link_prepare_wakeup(struct tipc_link *l)
926 {
927 	struct sk_buff_head *wakeupq = &l->wakeupq;
928 	struct sk_buff_head *inputq = l->inputq;
929 	struct sk_buff *skb, *tmp;
930 	struct sk_buff_head tmpq;
931 	int avail[5] = {0,};
932 	int imp = 0;
933 
934 	__skb_queue_head_init(&tmpq);
935 
936 	for (; imp <= TIPC_SYSTEM_IMPORTANCE; imp++)
937 		avail[imp] = l->backlog[imp].limit - l->backlog[imp].len;
938 
939 	skb_queue_walk_safe(wakeupq, skb, tmp) {
940 		imp = TIPC_SKB_CB(skb)->chain_imp;
941 		if (avail[imp] <= 0)
942 			continue;
943 		avail[imp]--;
944 		__skb_unlink(skb, wakeupq);
945 		__skb_queue_tail(&tmpq, skb);
946 	}
947 
948 	spin_lock_bh(&inputq->lock);
949 	skb_queue_splice_tail(&tmpq, inputq);
950 	spin_unlock_bh(&inputq->lock);
951 
952 }
953 
954 /**
955  * tipc_link_set_skb_retransmit_time - set the time at which retransmission of
956  *                                     the given skb should be next attempted
957  * @skb: skb to set a future retransmission time for
958  * @l: link the skb will be transmitted on
959  */
960 static void tipc_link_set_skb_retransmit_time(struct sk_buff *skb,
961 					      struct tipc_link *l)
962 {
963 	if (link_is_bc_sndlink(l))
964 		TIPC_SKB_CB(skb)->nxt_retr = TIPC_BC_RETR_LIM;
965 	else
966 		TIPC_SKB_CB(skb)->nxt_retr = TIPC_UC_RETR_TIME;
967 }
968 
969 void tipc_link_reset(struct tipc_link *l)
970 {
971 	struct sk_buff_head list;
972 	u32 imp;
973 
974 	__skb_queue_head_init(&list);
975 
976 	l->in_session = false;
977 	/* Force re-synch of peer session number before establishing */
978 	l->peer_session--;
979 	l->session++;
980 	l->mtu = l->advertised_mtu;
981 
982 	spin_lock_bh(&l->wakeupq.lock);
983 	skb_queue_splice_init(&l->wakeupq, &list);
984 	spin_unlock_bh(&l->wakeupq.lock);
985 
986 	spin_lock_bh(&l->inputq->lock);
987 	skb_queue_splice_init(&list, l->inputq);
988 	spin_unlock_bh(&l->inputq->lock);
989 
990 	__skb_queue_purge(&l->transmq);
991 	__skb_queue_purge(&l->deferdq);
992 	__skb_queue_purge(&l->backlogq);
993 	__skb_queue_purge(&l->failover_deferdq);
994 	for (imp = 0; imp <= TIPC_SYSTEM_IMPORTANCE; imp++) {
995 		l->backlog[imp].len = 0;
996 		l->backlog[imp].target_bskb = NULL;
997 	}
998 	kfree_skb(l->reasm_buf);
999 	kfree_skb(l->reasm_tnlmsg);
1000 	kfree_skb(l->failover_reasm_skb);
1001 	l->reasm_buf = NULL;
1002 	l->reasm_tnlmsg = NULL;
1003 	l->failover_reasm_skb = NULL;
1004 	l->rcv_unacked = 0;
1005 	l->snd_nxt = 1;
1006 	l->rcv_nxt = 1;
1007 	l->snd_nxt_state = 1;
1008 	l->rcv_nxt_state = 1;
1009 	l->acked = 0;
1010 	l->last_gap = 0;
1011 	kfree(l->last_ga);
1012 	l->last_ga = NULL;
1013 	l->silent_intv_cnt = 0;
1014 	l->rst_cnt = 0;
1015 	l->bc_peer_is_up = false;
1016 	memset(&l->mon_state, 0, sizeof(l->mon_state));
1017 	tipc_link_reset_stats(l);
1018 }
1019 
1020 /**
1021  * tipc_link_xmit(): enqueue buffer list according to queue situation
1022  * @l: link to use
1023  * @list: chain of buffers containing message
1024  * @xmitq: returned list of packets to be sent by caller
1025  *
1026  * Consumes the buffer chain.
1027  * Messages at TIPC_SYSTEM_IMPORTANCE are always accepted
1028  * Return: 0 if success, or errno: -ELINKCONG, -EMSGSIZE or -ENOBUFS
1029  */
1030 int tipc_link_xmit(struct tipc_link *l, struct sk_buff_head *list,
1031 		   struct sk_buff_head *xmitq)
1032 {
1033 	struct sk_buff_head *backlogq = &l->backlogq;
1034 	struct sk_buff_head *transmq = &l->transmq;
1035 	struct sk_buff *skb, *_skb;
1036 	u16 bc_ack = l->bc_rcvlink->rcv_nxt - 1;
1037 	u16 ack = l->rcv_nxt - 1;
1038 	u16 seqno = l->snd_nxt;
1039 	int pkt_cnt = skb_queue_len(list);
1040 	unsigned int mss = tipc_link_mss(l);
1041 	unsigned int cwin = l->window;
1042 	unsigned int mtu = l->mtu;
1043 	struct tipc_msg *hdr;
1044 	bool new_bundle;
1045 	int rc = 0;
1046 	int imp;
1047 
1048 	if (pkt_cnt <= 0)
1049 		return 0;
1050 
1051 	hdr = buf_msg(skb_peek(list));
1052 	if (unlikely(msg_size(hdr) > mtu)) {
1053 		pr_warn("Too large msg, purging xmit list %d %d %d %d %d!\n",
1054 			skb_queue_len(list), msg_user(hdr),
1055 			msg_type(hdr), msg_size(hdr), mtu);
1056 		__skb_queue_purge(list);
1057 		return -EMSGSIZE;
1058 	}
1059 
1060 	imp = msg_importance(hdr);
1061 	/* Allow oversubscription of one data msg per source at congestion */
1062 	if (unlikely(l->backlog[imp].len >= l->backlog[imp].limit)) {
1063 		if (imp == TIPC_SYSTEM_IMPORTANCE) {
1064 			pr_warn("%s<%s>, link overflow", link_rst_msg, l->name);
1065 			return -ENOBUFS;
1066 		}
1067 		rc = link_schedule_user(l, hdr);
1068 	}
1069 
1070 	if (pkt_cnt > 1) {
1071 		l->stats.sent_fragmented++;
1072 		l->stats.sent_fragments += pkt_cnt;
1073 	}
1074 
1075 	/* Prepare each packet for sending, and add to relevant queue: */
1076 	while ((skb = __skb_dequeue(list))) {
1077 		if (likely(skb_queue_len(transmq) < cwin)) {
1078 			hdr = buf_msg(skb);
1079 			msg_set_seqno(hdr, seqno);
1080 			msg_set_ack(hdr, ack);
1081 			msg_set_bcast_ack(hdr, bc_ack);
1082 			_skb = skb_clone(skb, GFP_ATOMIC);
1083 			if (!_skb) {
1084 				kfree_skb(skb);
1085 				__skb_queue_purge(list);
1086 				return -ENOBUFS;
1087 			}
1088 			__skb_queue_tail(transmq, skb);
1089 			tipc_link_set_skb_retransmit_time(skb, l);
1090 			__skb_queue_tail(xmitq, _skb);
1091 			TIPC_SKB_CB(skb)->ackers = l->ackers;
1092 			l->rcv_unacked = 0;
1093 			l->stats.sent_pkts++;
1094 			seqno++;
1095 			continue;
1096 		}
1097 		if (tipc_msg_try_bundle(l->backlog[imp].target_bskb, &skb,
1098 					mss, l->addr, &new_bundle)) {
1099 			if (skb) {
1100 				/* Keep a ref. to the skb for next try */
1101 				l->backlog[imp].target_bskb = skb;
1102 				l->backlog[imp].len++;
1103 				__skb_queue_tail(backlogq, skb);
1104 			} else {
1105 				if (new_bundle) {
1106 					l->stats.sent_bundles++;
1107 					l->stats.sent_bundled++;
1108 				}
1109 				l->stats.sent_bundled++;
1110 			}
1111 			continue;
1112 		}
1113 		l->backlog[imp].target_bskb = NULL;
1114 		l->backlog[imp].len += (1 + skb_queue_len(list));
1115 		__skb_queue_tail(backlogq, skb);
1116 		skb_queue_splice_tail_init(list, backlogq);
1117 	}
1118 	l->snd_nxt = seqno;
1119 	return rc;
1120 }
1121 
1122 static void tipc_link_update_cwin(struct tipc_link *l, int released,
1123 				  bool retransmitted)
1124 {
1125 	int bklog_len = skb_queue_len(&l->backlogq);
1126 	struct sk_buff_head *txq = &l->transmq;
1127 	int txq_len = skb_queue_len(txq);
1128 	u16 cwin = l->window;
1129 
1130 	/* Enter fast recovery */
1131 	if (unlikely(retransmitted)) {
1132 		l->ssthresh = max_t(u16, l->window / 2, 300);
1133 		l->window = min_t(u16, l->ssthresh, l->window);
1134 		return;
1135 	}
1136 	/* Enter slow start */
1137 	if (unlikely(!released)) {
1138 		l->ssthresh = max_t(u16, l->window / 2, 300);
1139 		l->window = l->min_win;
1140 		return;
1141 	}
1142 	/* Don't increase window if no pressure on the transmit queue */
1143 	if (txq_len + bklog_len < cwin)
1144 		return;
1145 
1146 	/* Don't increase window if there are holes the transmit queue */
1147 	if (txq_len && l->snd_nxt - buf_seqno(skb_peek(txq)) != txq_len)
1148 		return;
1149 
1150 	l->cong_acks += released;
1151 
1152 	/* Slow start  */
1153 	if (cwin <= l->ssthresh) {
1154 		l->window = min_t(u16, cwin + released, l->max_win);
1155 		return;
1156 	}
1157 	/* Congestion avoidance */
1158 	if (l->cong_acks < cwin)
1159 		return;
1160 	l->window = min_t(u16, ++cwin, l->max_win);
1161 	l->cong_acks = 0;
1162 }
1163 
1164 static void tipc_link_advance_backlog(struct tipc_link *l,
1165 				      struct sk_buff_head *xmitq)
1166 {
1167 	u16 bc_ack = l->bc_rcvlink->rcv_nxt - 1;
1168 	struct sk_buff_head *txq = &l->transmq;
1169 	struct sk_buff *skb, *_skb;
1170 	u16 ack = l->rcv_nxt - 1;
1171 	u16 seqno = l->snd_nxt;
1172 	struct tipc_msg *hdr;
1173 	u16 cwin = l->window;
1174 	u32 imp;
1175 
1176 	while (skb_queue_len(txq) < cwin) {
1177 		skb = skb_peek(&l->backlogq);
1178 		if (!skb)
1179 			break;
1180 		_skb = skb_clone(skb, GFP_ATOMIC);
1181 		if (!_skb)
1182 			break;
1183 		__skb_dequeue(&l->backlogq);
1184 		hdr = buf_msg(skb);
1185 		imp = msg_importance(hdr);
1186 		l->backlog[imp].len--;
1187 		if (unlikely(skb == l->backlog[imp].target_bskb))
1188 			l->backlog[imp].target_bskb = NULL;
1189 		__skb_queue_tail(&l->transmq, skb);
1190 		tipc_link_set_skb_retransmit_time(skb, l);
1191 
1192 		__skb_queue_tail(xmitq, _skb);
1193 		TIPC_SKB_CB(skb)->ackers = l->ackers;
1194 		msg_set_seqno(hdr, seqno);
1195 		msg_set_ack(hdr, ack);
1196 		msg_set_bcast_ack(hdr, bc_ack);
1197 		l->rcv_unacked = 0;
1198 		l->stats.sent_pkts++;
1199 		seqno++;
1200 	}
1201 	l->snd_nxt = seqno;
1202 }
1203 
1204 /**
1205  * link_retransmit_failure() - Detect repeated retransmit failures
1206  * @l: tipc link sender
1207  * @r: tipc link receiver (= l in case of unicast)
1208  * @rc: returned code
1209  *
1210  * Return: true if the repeated retransmit failures happens, otherwise
1211  * false
1212  */
1213 static bool link_retransmit_failure(struct tipc_link *l, struct tipc_link *r,
1214 				    int *rc)
1215 {
1216 	struct sk_buff *skb = skb_peek(&l->transmq);
1217 	struct tipc_msg *hdr;
1218 
1219 	if (!skb)
1220 		return false;
1221 
1222 	if (!TIPC_SKB_CB(skb)->retr_cnt)
1223 		return false;
1224 
1225 	if (!time_after(jiffies, TIPC_SKB_CB(skb)->retr_stamp +
1226 			msecs_to_jiffies(r->tolerance * 10)))
1227 		return false;
1228 
1229 	hdr = buf_msg(skb);
1230 	if (link_is_bc_sndlink(l) && !less(r->acked, msg_seqno(hdr)))
1231 		return false;
1232 
1233 	pr_warn("Retransmission failure on link <%s>\n", l->name);
1234 	link_print(l, "State of link ");
1235 	pr_info("Failed msg: usr %u, typ %u, len %u, err %u\n",
1236 		msg_user(hdr), msg_type(hdr), msg_size(hdr), msg_errcode(hdr));
1237 	pr_info("sqno %u, prev: %x, dest: %x\n",
1238 		msg_seqno(hdr), msg_prevnode(hdr), msg_destnode(hdr));
1239 	pr_info("retr_stamp %d, retr_cnt %d\n",
1240 		jiffies_to_msecs(TIPC_SKB_CB(skb)->retr_stamp),
1241 		TIPC_SKB_CB(skb)->retr_cnt);
1242 
1243 	trace_tipc_list_dump(&l->transmq, true, "retrans failure!");
1244 	trace_tipc_link_dump(l, TIPC_DUMP_NONE, "retrans failure!");
1245 	trace_tipc_link_dump(r, TIPC_DUMP_NONE, "retrans failure!");
1246 
1247 	if (link_is_bc_sndlink(l)) {
1248 		r->state = LINK_RESET;
1249 		*rc |= TIPC_LINK_DOWN_EVT;
1250 	} else {
1251 		*rc |= tipc_link_fsm_evt(l, LINK_FAILURE_EVT);
1252 	}
1253 
1254 	return true;
1255 }
1256 
1257 /* tipc_data_input - deliver data and name distr msgs to upper layer
1258  *
1259  * Consumes buffer if message is of right type
1260  * Node lock must be held
1261  */
1262 static bool tipc_data_input(struct tipc_link *l, struct sk_buff *skb,
1263 			    struct sk_buff_head *inputq)
1264 {
1265 	struct sk_buff_head *mc_inputq = l->bc_rcvlink->inputq;
1266 	struct tipc_msg *hdr = buf_msg(skb);
1267 
1268 	switch (msg_user(hdr)) {
1269 	case TIPC_LOW_IMPORTANCE:
1270 	case TIPC_MEDIUM_IMPORTANCE:
1271 	case TIPC_HIGH_IMPORTANCE:
1272 	case TIPC_CRITICAL_IMPORTANCE:
1273 		if (unlikely(msg_in_group(hdr) || msg_mcast(hdr))) {
1274 			skb_queue_tail(mc_inputq, skb);
1275 			return true;
1276 		}
1277 		fallthrough;
1278 	case CONN_MANAGER:
1279 		skb_queue_tail(inputq, skb);
1280 		return true;
1281 	case GROUP_PROTOCOL:
1282 		skb_queue_tail(mc_inputq, skb);
1283 		return true;
1284 	case NAME_DISTRIBUTOR:
1285 		l->bc_rcvlink->state = LINK_ESTABLISHED;
1286 		skb_queue_tail(l->namedq, skb);
1287 		return true;
1288 	case MSG_BUNDLER:
1289 	case TUNNEL_PROTOCOL:
1290 	case MSG_FRAGMENTER:
1291 	case BCAST_PROTOCOL:
1292 		return false;
1293 #ifdef CONFIG_TIPC_CRYPTO
1294 	case MSG_CRYPTO:
1295 		tipc_crypto_msg_rcv(l->net, skb);
1296 		return true;
1297 #endif
1298 	default:
1299 		pr_warn("Dropping received illegal msg type\n");
1300 		kfree_skb(skb);
1301 		return true;
1302 	}
1303 }
1304 
1305 /* tipc_link_input - process packet that has passed link protocol check
1306  *
1307  * Consumes buffer
1308  */
1309 static int tipc_link_input(struct tipc_link *l, struct sk_buff *skb,
1310 			   struct sk_buff_head *inputq,
1311 			   struct sk_buff **reasm_skb)
1312 {
1313 	struct tipc_msg *hdr = buf_msg(skb);
1314 	struct sk_buff *iskb;
1315 	struct sk_buff_head tmpq;
1316 	int usr = msg_user(hdr);
1317 	int pos = 0;
1318 
1319 	if (usr == MSG_BUNDLER) {
1320 		skb_queue_head_init(&tmpq);
1321 		l->stats.recv_bundles++;
1322 		l->stats.recv_bundled += msg_msgcnt(hdr);
1323 		while (tipc_msg_extract(skb, &iskb, &pos))
1324 			tipc_data_input(l, iskb, &tmpq);
1325 		tipc_skb_queue_splice_tail(&tmpq, inputq);
1326 		return 0;
1327 	} else if (usr == MSG_FRAGMENTER) {
1328 		l->stats.recv_fragments++;
1329 		if (tipc_buf_append(reasm_skb, &skb)) {
1330 			l->stats.recv_fragmented++;
1331 			tipc_data_input(l, skb, inputq);
1332 		} else if (!*reasm_skb && !link_is_bc_rcvlink(l)) {
1333 			pr_warn_ratelimited("Unable to build fragment list\n");
1334 			return tipc_link_fsm_evt(l, LINK_FAILURE_EVT);
1335 		}
1336 		return 0;
1337 	} else if (usr == BCAST_PROTOCOL) {
1338 		tipc_bcast_lock(l->net);
1339 		tipc_link_bc_init_rcv(l->bc_rcvlink, hdr);
1340 		tipc_bcast_unlock(l->net);
1341 	}
1342 
1343 	kfree_skb(skb);
1344 	return 0;
1345 }
1346 
1347 /* tipc_link_tnl_rcv() - receive TUNNEL_PROTOCOL message, drop or process the
1348  *			 inner message along with the ones in the old link's
1349  *			 deferdq
1350  * @l: tunnel link
1351  * @skb: TUNNEL_PROTOCOL message
1352  * @inputq: queue to put messages ready for delivery
1353  */
1354 static int tipc_link_tnl_rcv(struct tipc_link *l, struct sk_buff *skb,
1355 			     struct sk_buff_head *inputq)
1356 {
1357 	struct sk_buff **reasm_skb = &l->failover_reasm_skb;
1358 	struct sk_buff **reasm_tnlmsg = &l->reasm_tnlmsg;
1359 	struct sk_buff_head *fdefq = &l->failover_deferdq;
1360 	struct tipc_msg *hdr = buf_msg(skb);
1361 	struct sk_buff *iskb;
1362 	int ipos = 0;
1363 	int rc = 0;
1364 	u16 seqno;
1365 
1366 	if (msg_type(hdr) == SYNCH_MSG) {
1367 		kfree_skb(skb);
1368 		return 0;
1369 	}
1370 
1371 	/* Not a fragment? */
1372 	if (likely(!msg_nof_fragms(hdr))) {
1373 		if (unlikely(!tipc_msg_extract(skb, &iskb, &ipos))) {
1374 			pr_warn_ratelimited("Unable to extract msg, defq: %d\n",
1375 					    skb_queue_len(fdefq));
1376 			return 0;
1377 		}
1378 		kfree_skb(skb);
1379 	} else {
1380 		/* Set fragment type for buf_append */
1381 		if (msg_fragm_no(hdr) == 1)
1382 			msg_set_type(hdr, FIRST_FRAGMENT);
1383 		else if (msg_fragm_no(hdr) < msg_nof_fragms(hdr))
1384 			msg_set_type(hdr, FRAGMENT);
1385 		else
1386 			msg_set_type(hdr, LAST_FRAGMENT);
1387 
1388 		if (!tipc_buf_append(reasm_tnlmsg, &skb)) {
1389 			/* Successful but non-complete reassembly? */
1390 			if (*reasm_tnlmsg || link_is_bc_rcvlink(l))
1391 				return 0;
1392 			pr_warn_ratelimited("Unable to reassemble tunnel msg\n");
1393 			return tipc_link_fsm_evt(l, LINK_FAILURE_EVT);
1394 		}
1395 		iskb = skb;
1396 	}
1397 
1398 	do {
1399 		seqno = buf_seqno(iskb);
1400 		if (unlikely(less(seqno, l->drop_point))) {
1401 			kfree_skb(iskb);
1402 			continue;
1403 		}
1404 		if (unlikely(seqno != l->drop_point)) {
1405 			__tipc_skb_queue_sorted(fdefq, seqno, iskb);
1406 			continue;
1407 		}
1408 
1409 		l->drop_point++;
1410 		if (!tipc_data_input(l, iskb, inputq))
1411 			rc |= tipc_link_input(l, iskb, inputq, reasm_skb);
1412 		if (unlikely(rc))
1413 			break;
1414 	} while ((iskb = __tipc_skb_dequeue(fdefq, l->drop_point)));
1415 
1416 	return rc;
1417 }
1418 
1419 /**
1420  * tipc_get_gap_ack_blks - get Gap ACK blocks from PROTOCOL/STATE_MSG
1421  * @ga: returned pointer to the Gap ACK blocks if any
1422  * @l: the tipc link
1423  * @hdr: the PROTOCOL/STATE_MSG header
1424  * @uc: desired Gap ACK blocks type, i.e. unicast (= 1) or broadcast (= 0)
1425  *
1426  * Return: the total Gap ACK blocks size
1427  */
1428 u16 tipc_get_gap_ack_blks(struct tipc_gap_ack_blks **ga, struct tipc_link *l,
1429 			  struct tipc_msg *hdr, bool uc)
1430 {
1431 	struct tipc_gap_ack_blks *p;
1432 	u16 sz = 0;
1433 
1434 	/* Does peer support the Gap ACK blocks feature? */
1435 	if (l->peer_caps & TIPC_GAP_ACK_BLOCK) {
1436 		p = (struct tipc_gap_ack_blks *)msg_data(hdr);
1437 		sz = ntohs(p->len);
1438 		/* Sanity check */
1439 		if (sz == struct_size(p, gacks, p->ugack_cnt + p->bgack_cnt)) {
1440 			/* Good, check if the desired type exists */
1441 			if ((uc && p->ugack_cnt) || (!uc && p->bgack_cnt))
1442 				goto ok;
1443 		/* Backward compatible: peer might not support bc, but uc? */
1444 		} else if (uc && sz == struct_size(p, gacks, p->ugack_cnt)) {
1445 			if (p->ugack_cnt) {
1446 				p->bgack_cnt = 0;
1447 				goto ok;
1448 			}
1449 		}
1450 	}
1451 	/* Other cases: ignore! */
1452 	p = NULL;
1453 
1454 ok:
1455 	*ga = p;
1456 	return sz;
1457 }
1458 
1459 static u8 __tipc_build_gap_ack_blks(struct tipc_gap_ack_blks *ga,
1460 				    struct tipc_link *l, u8 start_index)
1461 {
1462 	struct tipc_gap_ack *gacks = &ga->gacks[start_index];
1463 	struct sk_buff *skb = skb_peek(&l->deferdq);
1464 	u16 expect, seqno = 0;
1465 	u8 n = 0;
1466 
1467 	if (!skb)
1468 		return 0;
1469 
1470 	expect = buf_seqno(skb);
1471 	skb_queue_walk(&l->deferdq, skb) {
1472 		seqno = buf_seqno(skb);
1473 		if (unlikely(more(seqno, expect))) {
1474 			gacks[n].ack = htons(expect - 1);
1475 			gacks[n].gap = htons(seqno - expect);
1476 			if (++n >= MAX_GAP_ACK_BLKS / 2) {
1477 				pr_info_ratelimited("Gacks on %s: %d, ql: %d!\n",
1478 						    l->name, n,
1479 						    skb_queue_len(&l->deferdq));
1480 				return n;
1481 			}
1482 		} else if (unlikely(less(seqno, expect))) {
1483 			pr_warn("Unexpected skb in deferdq!\n");
1484 			continue;
1485 		}
1486 		expect = seqno + 1;
1487 	}
1488 
1489 	/* last block */
1490 	gacks[n].ack = htons(seqno);
1491 	gacks[n].gap = 0;
1492 	n++;
1493 	return n;
1494 }
1495 
1496 /* tipc_build_gap_ack_blks - build Gap ACK blocks
1497  * @l: tipc unicast link
1498  * @hdr: the tipc message buffer to store the Gap ACK blocks after built
1499  *
1500  * The function builds Gap ACK blocks for both the unicast & broadcast receiver
1501  * links of a certain peer, the buffer after built has the network data format
1502  * as found at the struct tipc_gap_ack_blks definition.
1503  *
1504  * returns the actual allocated memory size
1505  */
1506 static u16 tipc_build_gap_ack_blks(struct tipc_link *l, struct tipc_msg *hdr)
1507 {
1508 	struct tipc_link *bcl = l->bc_rcvlink;
1509 	struct tipc_gap_ack_blks *ga;
1510 	u16 len;
1511 
1512 	ga = (struct tipc_gap_ack_blks *)msg_data(hdr);
1513 
1514 	/* Start with broadcast link first */
1515 	tipc_bcast_lock(bcl->net);
1516 	msg_set_bcast_ack(hdr, bcl->rcv_nxt - 1);
1517 	msg_set_bc_gap(hdr, link_bc_rcv_gap(bcl));
1518 	ga->bgack_cnt = __tipc_build_gap_ack_blks(ga, bcl, 0);
1519 	tipc_bcast_unlock(bcl->net);
1520 
1521 	/* Now for unicast link, but an explicit NACK only (???) */
1522 	ga->ugack_cnt = (msg_seq_gap(hdr)) ?
1523 			__tipc_build_gap_ack_blks(ga, l, ga->bgack_cnt) : 0;
1524 
1525 	/* Total len */
1526 	len = struct_size(ga, gacks, ga->bgack_cnt + ga->ugack_cnt);
1527 	ga->len = htons(len);
1528 	return len;
1529 }
1530 
1531 /* tipc_link_advance_transmq - advance TIPC link transmq queue by releasing
1532  *			       acked packets, also doing retransmissions if
1533  *			       gaps found
1534  * @l: tipc link with transmq queue to be advanced
1535  * @r: tipc link "receiver" i.e. in case of broadcast (= "l" if unicast)
1536  * @acked: seqno of last packet acked by peer without any gaps before
1537  * @gap: # of gap packets
1538  * @ga: buffer pointer to Gap ACK blocks from peer
1539  * @xmitq: queue for accumulating the retransmitted packets if any
1540  * @retransmitted: returned boolean value if a retransmission is really issued
1541  * @rc: returned code e.g. TIPC_LINK_DOWN_EVT if a repeated retransmit failures
1542  *      happens (- unlikely case)
1543  *
1544  * Return: the number of packets released from the link transmq
1545  */
1546 static int tipc_link_advance_transmq(struct tipc_link *l, struct tipc_link *r,
1547 				     u16 acked, u16 gap,
1548 				     struct tipc_gap_ack_blks *ga,
1549 				     struct sk_buff_head *xmitq,
1550 				     bool *retransmitted, int *rc)
1551 {
1552 	struct tipc_gap_ack_blks *last_ga = r->last_ga, *this_ga = NULL;
1553 	struct tipc_gap_ack *gacks = NULL;
1554 	struct sk_buff *skb, *_skb, *tmp;
1555 	struct tipc_msg *hdr;
1556 	u32 qlen = skb_queue_len(&l->transmq);
1557 	u16 nacked = acked, ngap = gap, gack_cnt = 0;
1558 	u16 bc_ack = l->bc_rcvlink->rcv_nxt - 1;
1559 	u16 ack = l->rcv_nxt - 1;
1560 	u16 seqno, n = 0;
1561 	u16 end = r->acked, start = end, offset = r->last_gap;
1562 	u16 si = (last_ga) ? last_ga->start_index : 0;
1563 	bool is_uc = !link_is_bc_sndlink(l);
1564 	bool bc_has_acked = false;
1565 
1566 	trace_tipc_link_retrans(r, acked + 1, acked + gap, &l->transmq);
1567 
1568 	/* Determine Gap ACK blocks if any for the particular link */
1569 	if (ga && is_uc) {
1570 		/* Get the Gap ACKs, uc part */
1571 		gack_cnt = ga->ugack_cnt;
1572 		gacks = &ga->gacks[ga->bgack_cnt];
1573 	} else if (ga) {
1574 		/* Copy the Gap ACKs, bc part, for later renewal if needed */
1575 		this_ga = kmemdup(ga, struct_size(ga, gacks, ga->bgack_cnt),
1576 				  GFP_ATOMIC);
1577 		if (likely(this_ga)) {
1578 			this_ga->start_index = 0;
1579 			/* Start with the bc Gap ACKs */
1580 			gack_cnt = this_ga->bgack_cnt;
1581 			gacks = &this_ga->gacks[0];
1582 		} else {
1583 			/* Hmm, we can get in trouble..., simply ignore it */
1584 			pr_warn_ratelimited("Ignoring bc Gap ACKs, no memory\n");
1585 		}
1586 	}
1587 
1588 	/* Advance the link transmq */
1589 	skb_queue_walk_safe(&l->transmq, skb, tmp) {
1590 		seqno = buf_seqno(skb);
1591 
1592 next_gap_ack:
1593 		if (less_eq(seqno, nacked)) {
1594 			if (is_uc)
1595 				goto release;
1596 			/* Skip packets peer has already acked */
1597 			if (!more(seqno, r->acked))
1598 				continue;
1599 			/* Get the next of last Gap ACK blocks */
1600 			while (more(seqno, end)) {
1601 				if (!last_ga || si >= last_ga->bgack_cnt)
1602 					break;
1603 				start = end + offset + 1;
1604 				end = ntohs(last_ga->gacks[si].ack);
1605 				offset = ntohs(last_ga->gacks[si].gap);
1606 				si++;
1607 				WARN_ONCE(more(start, end) ||
1608 					  (!offset &&
1609 					   si < last_ga->bgack_cnt) ||
1610 					  si > MAX_GAP_ACK_BLKS,
1611 					  "Corrupted Gap ACK: %d %d %d %d %d\n",
1612 					  start, end, offset, si,
1613 					  last_ga->bgack_cnt);
1614 			}
1615 			/* Check against the last Gap ACK block */
1616 			if (in_range(seqno, start, end))
1617 				continue;
1618 			/* Update/release the packet peer is acking */
1619 			bc_has_acked = true;
1620 			if (--TIPC_SKB_CB(skb)->ackers)
1621 				continue;
1622 release:
1623 			/* release skb */
1624 			__skb_unlink(skb, &l->transmq);
1625 			kfree_skb(skb);
1626 		} else if (less_eq(seqno, nacked + ngap)) {
1627 			/* First gap: check if repeated retrans failures? */
1628 			if (unlikely(seqno == acked + 1 &&
1629 				     link_retransmit_failure(l, r, rc))) {
1630 				/* Ignore this bc Gap ACKs if any */
1631 				kfree(this_ga);
1632 				this_ga = NULL;
1633 				break;
1634 			}
1635 			/* retransmit skb if unrestricted*/
1636 			if (time_before(jiffies, TIPC_SKB_CB(skb)->nxt_retr))
1637 				continue;
1638 			tipc_link_set_skb_retransmit_time(skb, l);
1639 			_skb = pskb_copy(skb, GFP_ATOMIC);
1640 			if (!_skb)
1641 				continue;
1642 			hdr = buf_msg(_skb);
1643 			msg_set_ack(hdr, ack);
1644 			msg_set_bcast_ack(hdr, bc_ack);
1645 			_skb->priority = TC_PRIO_CONTROL;
1646 			__skb_queue_tail(xmitq, _skb);
1647 			l->stats.retransmitted++;
1648 			if (!is_uc)
1649 				r->stats.retransmitted++;
1650 			*retransmitted = true;
1651 			/* Increase actual retrans counter & mark first time */
1652 			if (!TIPC_SKB_CB(skb)->retr_cnt++)
1653 				TIPC_SKB_CB(skb)->retr_stamp = jiffies;
1654 		} else {
1655 			/* retry with Gap ACK blocks if any */
1656 			if (n >= gack_cnt)
1657 				break;
1658 			nacked = ntohs(gacks[n].ack);
1659 			ngap = ntohs(gacks[n].gap);
1660 			n++;
1661 			goto next_gap_ack;
1662 		}
1663 	}
1664 
1665 	/* Renew last Gap ACK blocks for bc if needed */
1666 	if (bc_has_acked) {
1667 		if (this_ga) {
1668 			kfree(last_ga);
1669 			r->last_ga = this_ga;
1670 			r->last_gap = gap;
1671 		} else if (last_ga) {
1672 			if (less(acked, start)) {
1673 				si--;
1674 				offset = start - acked - 1;
1675 			} else if (less(acked, end)) {
1676 				acked = end;
1677 			}
1678 			if (si < last_ga->bgack_cnt) {
1679 				last_ga->start_index = si;
1680 				r->last_gap = offset;
1681 			} else {
1682 				kfree(last_ga);
1683 				r->last_ga = NULL;
1684 				r->last_gap = 0;
1685 			}
1686 		} else {
1687 			r->last_gap = 0;
1688 		}
1689 		r->acked = acked;
1690 	} else {
1691 		kfree(this_ga);
1692 	}
1693 
1694 	return qlen - skb_queue_len(&l->transmq);
1695 }
1696 
1697 /* tipc_link_build_state_msg: prepare link state message for transmission
1698  *
1699  * Note that sending of broadcast ack is coordinated among nodes, to reduce
1700  * risk of ack storms towards the sender
1701  */
1702 int tipc_link_build_state_msg(struct tipc_link *l, struct sk_buff_head *xmitq)
1703 {
1704 	if (!l)
1705 		return 0;
1706 
1707 	/* Broadcast ACK must be sent via a unicast link => defer to caller */
1708 	if (link_is_bc_rcvlink(l)) {
1709 		if (((l->rcv_nxt ^ tipc_own_addr(l->net)) & 0xf) != 0xf)
1710 			return 0;
1711 		l->rcv_unacked = 0;
1712 
1713 		/* Use snd_nxt to store peer's snd_nxt in broadcast rcv link */
1714 		l->snd_nxt = l->rcv_nxt;
1715 		return TIPC_LINK_SND_STATE;
1716 	}
1717 	/* Unicast ACK */
1718 	l->rcv_unacked = 0;
1719 	l->stats.sent_acks++;
1720 	tipc_link_build_proto_msg(l, STATE_MSG, 0, 0, 0, 0, 0, xmitq);
1721 	return 0;
1722 }
1723 
1724 /* tipc_link_build_reset_msg: prepare link RESET or ACTIVATE message
1725  */
1726 void tipc_link_build_reset_msg(struct tipc_link *l, struct sk_buff_head *xmitq)
1727 {
1728 	int mtyp = RESET_MSG;
1729 	struct sk_buff *skb;
1730 
1731 	if (l->state == LINK_ESTABLISHING)
1732 		mtyp = ACTIVATE_MSG;
1733 
1734 	tipc_link_build_proto_msg(l, mtyp, 0, 0, 0, 0, 0, xmitq);
1735 
1736 	/* Inform peer that this endpoint is going down if applicable */
1737 	skb = skb_peek_tail(xmitq);
1738 	if (skb && (l->state == LINK_RESET))
1739 		msg_set_peer_stopping(buf_msg(skb), 1);
1740 }
1741 
1742 /* tipc_link_build_nack_msg: prepare link nack message for transmission
1743  * Note that sending of broadcast NACK is coordinated among nodes, to
1744  * reduce the risk of NACK storms towards the sender
1745  */
1746 static int tipc_link_build_nack_msg(struct tipc_link *l,
1747 				    struct sk_buff_head *xmitq)
1748 {
1749 	u32 def_cnt = ++l->stats.deferred_recv;
1750 	struct sk_buff_head *dfq = &l->deferdq;
1751 	u32 defq_len = skb_queue_len(dfq);
1752 	int match1, match2;
1753 
1754 	if (link_is_bc_rcvlink(l)) {
1755 		match1 = def_cnt & 0xf;
1756 		match2 = tipc_own_addr(l->net) & 0xf;
1757 		if (match1 == match2)
1758 			return TIPC_LINK_SND_STATE;
1759 		return 0;
1760 	}
1761 
1762 	if (defq_len >= 3 && !((defq_len - 3) % 16)) {
1763 		u16 rcvgap = buf_seqno(skb_peek(dfq)) - l->rcv_nxt;
1764 
1765 		tipc_link_build_proto_msg(l, STATE_MSG, 0, 0,
1766 					  rcvgap, 0, 0, xmitq);
1767 	}
1768 	return 0;
1769 }
1770 
1771 /* tipc_link_rcv - process TIPC packets/messages arriving from off-node
1772  * @l: the link that should handle the message
1773  * @skb: TIPC packet
1774  * @xmitq: queue to place packets to be sent after this call
1775  */
1776 int tipc_link_rcv(struct tipc_link *l, struct sk_buff *skb,
1777 		  struct sk_buff_head *xmitq)
1778 {
1779 	struct sk_buff_head *defq = &l->deferdq;
1780 	struct tipc_msg *hdr = buf_msg(skb);
1781 	u16 seqno, rcv_nxt, win_lim;
1782 	int released = 0;
1783 	int rc = 0;
1784 
1785 	/* Verify and update link state */
1786 	if (unlikely(msg_user(hdr) == LINK_PROTOCOL))
1787 		return tipc_link_proto_rcv(l, skb, xmitq);
1788 
1789 	/* Don't send probe at next timeout expiration */
1790 	l->silent_intv_cnt = 0;
1791 
1792 	do {
1793 		hdr = buf_msg(skb);
1794 		seqno = msg_seqno(hdr);
1795 		rcv_nxt = l->rcv_nxt;
1796 		win_lim = rcv_nxt + TIPC_MAX_LINK_WIN;
1797 
1798 		if (unlikely(!link_is_up(l))) {
1799 			if (l->state == LINK_ESTABLISHING)
1800 				rc = TIPC_LINK_UP_EVT;
1801 			kfree_skb(skb);
1802 			break;
1803 		}
1804 
1805 		/* Drop if outside receive window */
1806 		if (unlikely(less(seqno, rcv_nxt) || more(seqno, win_lim))) {
1807 			l->stats.duplicates++;
1808 			kfree_skb(skb);
1809 			break;
1810 		}
1811 		released += tipc_link_advance_transmq(l, l, msg_ack(hdr), 0,
1812 						      NULL, NULL, NULL, NULL);
1813 
1814 		/* Defer delivery if sequence gap */
1815 		if (unlikely(seqno != rcv_nxt)) {
1816 			if (!__tipc_skb_queue_sorted(defq, seqno, skb))
1817 				l->stats.duplicates++;
1818 			rc |= tipc_link_build_nack_msg(l, xmitq);
1819 			break;
1820 		}
1821 
1822 		/* Deliver packet */
1823 		l->rcv_nxt++;
1824 		l->stats.recv_pkts++;
1825 
1826 		if (unlikely(msg_user(hdr) == TUNNEL_PROTOCOL))
1827 			rc |= tipc_link_tnl_rcv(l, skb, l->inputq);
1828 		else if (!tipc_data_input(l, skb, l->inputq))
1829 			rc |= tipc_link_input(l, skb, l->inputq, &l->reasm_buf);
1830 		if (unlikely(++l->rcv_unacked >= TIPC_MIN_LINK_WIN))
1831 			rc |= tipc_link_build_state_msg(l, xmitq);
1832 		if (unlikely(rc & ~TIPC_LINK_SND_STATE))
1833 			break;
1834 	} while ((skb = __tipc_skb_dequeue(defq, l->rcv_nxt)));
1835 
1836 	/* Forward queues and wake up waiting users */
1837 	if (released) {
1838 		tipc_link_update_cwin(l, released, 0);
1839 		tipc_link_advance_backlog(l, xmitq);
1840 		if (unlikely(!skb_queue_empty(&l->wakeupq)))
1841 			link_prepare_wakeup(l);
1842 	}
1843 	return rc;
1844 }
1845 
1846 static void tipc_link_build_proto_msg(struct tipc_link *l, int mtyp, bool probe,
1847 				      bool probe_reply, u16 rcvgap,
1848 				      int tolerance, int priority,
1849 				      struct sk_buff_head *xmitq)
1850 {
1851 	struct tipc_mon_state *mstate = &l->mon_state;
1852 	struct sk_buff_head *dfq = &l->deferdq;
1853 	struct tipc_link *bcl = l->bc_rcvlink;
1854 	struct tipc_msg *hdr;
1855 	struct sk_buff *skb;
1856 	bool node_up = link_is_up(bcl);
1857 	u16 glen = 0, bc_rcvgap = 0;
1858 	int dlen = 0;
1859 	void *data;
1860 
1861 	/* Don't send protocol message during reset or link failover */
1862 	if (tipc_link_is_blocked(l))
1863 		return;
1864 
1865 	if (!tipc_link_is_up(l) && (mtyp == STATE_MSG))
1866 		return;
1867 
1868 	if ((probe || probe_reply) && !skb_queue_empty(dfq))
1869 		rcvgap = buf_seqno(skb_peek(dfq)) - l->rcv_nxt;
1870 
1871 	skb = tipc_msg_create(LINK_PROTOCOL, mtyp, INT_H_SIZE,
1872 			      tipc_max_domain_size + MAX_GAP_ACK_BLKS_SZ,
1873 			      l->addr, tipc_own_addr(l->net), 0, 0, 0);
1874 	if (!skb)
1875 		return;
1876 
1877 	hdr = buf_msg(skb);
1878 	data = msg_data(hdr);
1879 	msg_set_session(hdr, l->session);
1880 	msg_set_bearer_id(hdr, l->bearer_id);
1881 	msg_set_net_plane(hdr, l->net_plane);
1882 	msg_set_next_sent(hdr, l->snd_nxt);
1883 	msg_set_ack(hdr, l->rcv_nxt - 1);
1884 	msg_set_bcast_ack(hdr, bcl->rcv_nxt - 1);
1885 	msg_set_bc_ack_invalid(hdr, !node_up);
1886 	msg_set_last_bcast(hdr, l->bc_sndlink->snd_nxt - 1);
1887 	msg_set_link_tolerance(hdr, tolerance);
1888 	msg_set_linkprio(hdr, priority);
1889 	msg_set_redundant_link(hdr, node_up);
1890 	msg_set_seq_gap(hdr, 0);
1891 	msg_set_seqno(hdr, l->snd_nxt + U16_MAX / 2);
1892 
1893 	if (mtyp == STATE_MSG) {
1894 		if (l->peer_caps & TIPC_LINK_PROTO_SEQNO)
1895 			msg_set_seqno(hdr, l->snd_nxt_state++);
1896 		msg_set_seq_gap(hdr, rcvgap);
1897 		bc_rcvgap = link_bc_rcv_gap(bcl);
1898 		msg_set_bc_gap(hdr, bc_rcvgap);
1899 		msg_set_probe(hdr, probe);
1900 		msg_set_is_keepalive(hdr, probe || probe_reply);
1901 		if (l->peer_caps & TIPC_GAP_ACK_BLOCK)
1902 			glen = tipc_build_gap_ack_blks(l, hdr);
1903 		tipc_mon_prep(l->net, data + glen, &dlen, mstate, l->bearer_id);
1904 		msg_set_size(hdr, INT_H_SIZE + glen + dlen);
1905 		skb_trim(skb, INT_H_SIZE + glen + dlen);
1906 		l->stats.sent_states++;
1907 		l->rcv_unacked = 0;
1908 	} else {
1909 		/* RESET_MSG or ACTIVATE_MSG */
1910 		if (mtyp == ACTIVATE_MSG) {
1911 			msg_set_dest_session_valid(hdr, 1);
1912 			msg_set_dest_session(hdr, l->peer_session);
1913 		}
1914 		msg_set_max_pkt(hdr, l->advertised_mtu);
1915 		strcpy(data, l->if_name);
1916 		msg_set_size(hdr, INT_H_SIZE + TIPC_MAX_IF_NAME);
1917 		skb_trim(skb, INT_H_SIZE + TIPC_MAX_IF_NAME);
1918 	}
1919 	if (probe)
1920 		l->stats.sent_probes++;
1921 	if (rcvgap)
1922 		l->stats.sent_nacks++;
1923 	if (bc_rcvgap)
1924 		bcl->stats.sent_nacks++;
1925 	skb->priority = TC_PRIO_CONTROL;
1926 	__skb_queue_tail(xmitq, skb);
1927 	trace_tipc_proto_build(skb, false, l->name);
1928 }
1929 
1930 void tipc_link_create_dummy_tnl_msg(struct tipc_link *l,
1931 				    struct sk_buff_head *xmitq)
1932 {
1933 	u32 onode = tipc_own_addr(l->net);
1934 	struct tipc_msg *hdr, *ihdr;
1935 	struct sk_buff_head tnlq;
1936 	struct sk_buff *skb;
1937 	u32 dnode = l->addr;
1938 
1939 	__skb_queue_head_init(&tnlq);
1940 	skb = tipc_msg_create(TUNNEL_PROTOCOL, FAILOVER_MSG,
1941 			      INT_H_SIZE, BASIC_H_SIZE,
1942 			      dnode, onode, 0, 0, 0);
1943 	if (!skb) {
1944 		pr_warn("%sunable to create tunnel packet\n", link_co_err);
1945 		return;
1946 	}
1947 
1948 	hdr = buf_msg(skb);
1949 	msg_set_msgcnt(hdr, 1);
1950 	msg_set_bearer_id(hdr, l->peer_bearer_id);
1951 
1952 	ihdr = (struct tipc_msg *)msg_data(hdr);
1953 	tipc_msg_init(onode, ihdr, TIPC_LOW_IMPORTANCE, TIPC_DIRECT_MSG,
1954 		      BASIC_H_SIZE, dnode);
1955 	msg_set_errcode(ihdr, TIPC_ERR_NO_PORT);
1956 	__skb_queue_tail(&tnlq, skb);
1957 	tipc_link_xmit(l, &tnlq, xmitq);
1958 }
1959 
1960 /* tipc_link_tnl_prepare(): prepare and return a list of tunnel packets
1961  * with contents of the link's transmit and backlog queues.
1962  */
1963 void tipc_link_tnl_prepare(struct tipc_link *l, struct tipc_link *tnl,
1964 			   int mtyp, struct sk_buff_head *xmitq)
1965 {
1966 	struct sk_buff_head *fdefq = &tnl->failover_deferdq;
1967 	struct sk_buff *skb, *tnlskb;
1968 	struct tipc_msg *hdr, tnlhdr;
1969 	struct sk_buff_head *queue = &l->transmq;
1970 	struct sk_buff_head tmpxq, tnlq, frags;
1971 	u16 pktlen, pktcnt, seqno = l->snd_nxt;
1972 	bool pktcnt_need_update = false;
1973 	u16 syncpt;
1974 	int rc;
1975 
1976 	if (!tnl)
1977 		return;
1978 
1979 	__skb_queue_head_init(&tnlq);
1980 	/* Link Synching:
1981 	 * From now on, send only one single ("dummy") SYNCH message
1982 	 * to peer. The SYNCH message does not contain any data, just
1983 	 * a header conveying the synch point to the peer.
1984 	 */
1985 	if (mtyp == SYNCH_MSG && (tnl->peer_caps & TIPC_TUNNEL_ENHANCED)) {
1986 		tnlskb = tipc_msg_create(TUNNEL_PROTOCOL, SYNCH_MSG,
1987 					 INT_H_SIZE, 0, l->addr,
1988 					 tipc_own_addr(l->net),
1989 					 0, 0, 0);
1990 		if (!tnlskb) {
1991 			pr_warn("%sunable to create dummy SYNCH_MSG\n",
1992 				link_co_err);
1993 			return;
1994 		}
1995 
1996 		hdr = buf_msg(tnlskb);
1997 		syncpt = l->snd_nxt + skb_queue_len(&l->backlogq) - 1;
1998 		msg_set_syncpt(hdr, syncpt);
1999 		msg_set_bearer_id(hdr, l->peer_bearer_id);
2000 		__skb_queue_tail(&tnlq, tnlskb);
2001 		tipc_link_xmit(tnl, &tnlq, xmitq);
2002 		return;
2003 	}
2004 
2005 	__skb_queue_head_init(&tmpxq);
2006 	__skb_queue_head_init(&frags);
2007 	/* At least one packet required for safe algorithm => add dummy */
2008 	skb = tipc_msg_create(TIPC_LOW_IMPORTANCE, TIPC_DIRECT_MSG,
2009 			      BASIC_H_SIZE, 0, l->addr, tipc_own_addr(l->net),
2010 			      0, 0, TIPC_ERR_NO_PORT);
2011 	if (!skb) {
2012 		pr_warn("%sunable to create tunnel packet\n", link_co_err);
2013 		return;
2014 	}
2015 	__skb_queue_tail(&tnlq, skb);
2016 	tipc_link_xmit(l, &tnlq, &tmpxq);
2017 	__skb_queue_purge(&tmpxq);
2018 
2019 	/* Initialize reusable tunnel packet header */
2020 	tipc_msg_init(tipc_own_addr(l->net), &tnlhdr, TUNNEL_PROTOCOL,
2021 		      mtyp, INT_H_SIZE, l->addr);
2022 	if (mtyp == SYNCH_MSG)
2023 		pktcnt = l->snd_nxt - buf_seqno(skb_peek(&l->transmq));
2024 	else
2025 		pktcnt = skb_queue_len(&l->transmq);
2026 	pktcnt += skb_queue_len(&l->backlogq);
2027 	msg_set_msgcnt(&tnlhdr, pktcnt);
2028 	msg_set_bearer_id(&tnlhdr, l->peer_bearer_id);
2029 tnl:
2030 	/* Wrap each packet into a tunnel packet */
2031 	skb_queue_walk(queue, skb) {
2032 		hdr = buf_msg(skb);
2033 		if (queue == &l->backlogq)
2034 			msg_set_seqno(hdr, seqno++);
2035 		pktlen = msg_size(hdr);
2036 
2037 		/* Tunnel link MTU is not large enough? This could be
2038 		 * due to:
2039 		 * 1) Link MTU has just changed or set differently;
2040 		 * 2) Or FAILOVER on the top of a SYNCH message
2041 		 *
2042 		 * The 2nd case should not happen if peer supports
2043 		 * TIPC_TUNNEL_ENHANCED
2044 		 */
2045 		if (pktlen > tnl->mtu - INT_H_SIZE) {
2046 			if (mtyp == FAILOVER_MSG &&
2047 			    (tnl->peer_caps & TIPC_TUNNEL_ENHANCED)) {
2048 				rc = tipc_msg_fragment(skb, &tnlhdr, tnl->mtu,
2049 						       &frags);
2050 				if (rc) {
2051 					pr_warn("%sunable to frag msg: rc %d\n",
2052 						link_co_err, rc);
2053 					return;
2054 				}
2055 				pktcnt += skb_queue_len(&frags) - 1;
2056 				pktcnt_need_update = true;
2057 				skb_queue_splice_tail_init(&frags, &tnlq);
2058 				continue;
2059 			}
2060 			/* Unluckily, peer doesn't have TIPC_TUNNEL_ENHANCED
2061 			 * => Just warn it and return!
2062 			 */
2063 			pr_warn_ratelimited("%stoo large msg <%d, %d>: %d!\n",
2064 					    link_co_err, msg_user(hdr),
2065 					    msg_type(hdr), msg_size(hdr));
2066 			return;
2067 		}
2068 
2069 		msg_set_size(&tnlhdr, pktlen + INT_H_SIZE);
2070 		tnlskb = tipc_buf_acquire(pktlen + INT_H_SIZE, GFP_ATOMIC);
2071 		if (!tnlskb) {
2072 			pr_warn("%sunable to send packet\n", link_co_err);
2073 			return;
2074 		}
2075 		skb_copy_to_linear_data(tnlskb, &tnlhdr, INT_H_SIZE);
2076 		skb_copy_to_linear_data_offset(tnlskb, INT_H_SIZE, hdr, pktlen);
2077 		__skb_queue_tail(&tnlq, tnlskb);
2078 	}
2079 	if (queue != &l->backlogq) {
2080 		queue = &l->backlogq;
2081 		goto tnl;
2082 	}
2083 
2084 	if (pktcnt_need_update)
2085 		skb_queue_walk(&tnlq, skb) {
2086 			hdr = buf_msg(skb);
2087 			msg_set_msgcnt(hdr, pktcnt);
2088 		}
2089 
2090 	tipc_link_xmit(tnl, &tnlq, xmitq);
2091 
2092 	if (mtyp == FAILOVER_MSG) {
2093 		tnl->drop_point = l->rcv_nxt;
2094 		tnl->failover_reasm_skb = l->reasm_buf;
2095 		l->reasm_buf = NULL;
2096 
2097 		/* Failover the link's deferdq */
2098 		if (unlikely(!skb_queue_empty(fdefq))) {
2099 			pr_warn("Link failover deferdq not empty: %d!\n",
2100 				skb_queue_len(fdefq));
2101 			__skb_queue_purge(fdefq);
2102 		}
2103 		skb_queue_splice_init(&l->deferdq, fdefq);
2104 	}
2105 }
2106 
2107 /**
2108  * tipc_link_failover_prepare() - prepare tnl for link failover
2109  *
2110  * This is a special version of the precursor - tipc_link_tnl_prepare(),
2111  * see the tipc_node_link_failover() for details
2112  *
2113  * @l: failover link
2114  * @tnl: tunnel link
2115  * @xmitq: queue for messages to be xmited
2116  */
2117 void tipc_link_failover_prepare(struct tipc_link *l, struct tipc_link *tnl,
2118 				struct sk_buff_head *xmitq)
2119 {
2120 	struct sk_buff_head *fdefq = &tnl->failover_deferdq;
2121 
2122 	tipc_link_create_dummy_tnl_msg(tnl, xmitq);
2123 
2124 	/* This failover link endpoint was never established before,
2125 	 * so it has not received anything from peer.
2126 	 * Otherwise, it must be a normal failover situation or the
2127 	 * node has entered SELF_DOWN_PEER_LEAVING and both peer nodes
2128 	 * would have to start over from scratch instead.
2129 	 */
2130 	tnl->drop_point = 1;
2131 	tnl->failover_reasm_skb = NULL;
2132 
2133 	/* Initiate the link's failover deferdq */
2134 	if (unlikely(!skb_queue_empty(fdefq))) {
2135 		pr_warn("Link failover deferdq not empty: %d!\n",
2136 			skb_queue_len(fdefq));
2137 		__skb_queue_purge(fdefq);
2138 	}
2139 }
2140 
2141 /* tipc_link_validate_msg(): validate message against current link state
2142  * Returns true if message should be accepted, otherwise false
2143  */
2144 bool tipc_link_validate_msg(struct tipc_link *l, struct tipc_msg *hdr)
2145 {
2146 	u16 curr_session = l->peer_session;
2147 	u16 session = msg_session(hdr);
2148 	int mtyp = msg_type(hdr);
2149 
2150 	if (msg_user(hdr) != LINK_PROTOCOL)
2151 		return true;
2152 
2153 	switch (mtyp) {
2154 	case RESET_MSG:
2155 		if (!l->in_session)
2156 			return true;
2157 		/* Accept only RESET with new session number */
2158 		return more(session, curr_session);
2159 	case ACTIVATE_MSG:
2160 		if (!l->in_session)
2161 			return true;
2162 		/* Accept only ACTIVATE with new or current session number */
2163 		return !less(session, curr_session);
2164 	case STATE_MSG:
2165 		/* Accept only STATE with current session number */
2166 		if (!l->in_session)
2167 			return false;
2168 		if (session != curr_session)
2169 			return false;
2170 		/* Extra sanity check */
2171 		if (!link_is_up(l) && msg_ack(hdr))
2172 			return false;
2173 		if (!(l->peer_caps & TIPC_LINK_PROTO_SEQNO))
2174 			return true;
2175 		/* Accept only STATE with new sequence number */
2176 		return !less(msg_seqno(hdr), l->rcv_nxt_state);
2177 	default:
2178 		return false;
2179 	}
2180 }
2181 
2182 /* tipc_link_proto_rcv(): receive link level protocol message :
2183  * Note that network plane id propagates through the network, and may
2184  * change at any time. The node with lowest numerical id determines
2185  * network plane
2186  */
2187 static int tipc_link_proto_rcv(struct tipc_link *l, struct sk_buff *skb,
2188 			       struct sk_buff_head *xmitq)
2189 {
2190 	struct tipc_msg *hdr = buf_msg(skb);
2191 	struct tipc_gap_ack_blks *ga = NULL;
2192 	bool reply = msg_probe(hdr), retransmitted = false;
2193 	u16 dlen = msg_data_sz(hdr), glen = 0;
2194 	u16 peers_snd_nxt =  msg_next_sent(hdr);
2195 	u16 peers_tol = msg_link_tolerance(hdr);
2196 	u16 peers_prio = msg_linkprio(hdr);
2197 	u16 gap = msg_seq_gap(hdr);
2198 	u16 ack = msg_ack(hdr);
2199 	u16 rcv_nxt = l->rcv_nxt;
2200 	u16 rcvgap = 0;
2201 	int mtyp = msg_type(hdr);
2202 	int rc = 0, released;
2203 	char *if_name;
2204 	void *data;
2205 
2206 	trace_tipc_proto_rcv(skb, false, l->name);
2207 	if (tipc_link_is_blocked(l) || !xmitq)
2208 		goto exit;
2209 
2210 	if (tipc_own_addr(l->net) > msg_prevnode(hdr))
2211 		l->net_plane = msg_net_plane(hdr);
2212 
2213 	skb_linearize(skb);
2214 	hdr = buf_msg(skb);
2215 	data = msg_data(hdr);
2216 
2217 	if (!tipc_link_validate_msg(l, hdr)) {
2218 		trace_tipc_skb_dump(skb, false, "PROTO invalid (1)!");
2219 		trace_tipc_link_dump(l, TIPC_DUMP_NONE, "PROTO invalid (1)!");
2220 		goto exit;
2221 	}
2222 
2223 	switch (mtyp) {
2224 	case RESET_MSG:
2225 	case ACTIVATE_MSG:
2226 		/* Complete own link name with peer's interface name */
2227 		if_name =  strrchr(l->name, ':') + 1;
2228 		if (sizeof(l->name) - (if_name - l->name) <= TIPC_MAX_IF_NAME)
2229 			break;
2230 		if (msg_data_sz(hdr) < TIPC_MAX_IF_NAME)
2231 			break;
2232 		strncpy(if_name, data, TIPC_MAX_IF_NAME);
2233 
2234 		/* Update own tolerance if peer indicates a non-zero value */
2235 		if (in_range(peers_tol, TIPC_MIN_LINK_TOL, TIPC_MAX_LINK_TOL)) {
2236 			l->tolerance = peers_tol;
2237 			l->bc_rcvlink->tolerance = peers_tol;
2238 		}
2239 		/* Update own priority if peer's priority is higher */
2240 		if (in_range(peers_prio, l->priority + 1, TIPC_MAX_LINK_PRI))
2241 			l->priority = peers_prio;
2242 
2243 		/* If peer is going down we want full re-establish cycle */
2244 		if (msg_peer_stopping(hdr)) {
2245 			rc = tipc_link_fsm_evt(l, LINK_FAILURE_EVT);
2246 			break;
2247 		}
2248 
2249 		/* If this endpoint was re-created while peer was ESTABLISHING
2250 		 * it doesn't know current session number. Force re-synch.
2251 		 */
2252 		if (mtyp == ACTIVATE_MSG && msg_dest_session_valid(hdr) &&
2253 		    l->session != msg_dest_session(hdr)) {
2254 			if (less(l->session, msg_dest_session(hdr)))
2255 				l->session = msg_dest_session(hdr) + 1;
2256 			break;
2257 		}
2258 
2259 		/* ACTIVATE_MSG serves as PEER_RESET if link is already down */
2260 		if (mtyp == RESET_MSG || !link_is_up(l))
2261 			rc = tipc_link_fsm_evt(l, LINK_PEER_RESET_EVT);
2262 
2263 		/* ACTIVATE_MSG takes up link if it was already locally reset */
2264 		if (mtyp == ACTIVATE_MSG && l->state == LINK_ESTABLISHING)
2265 			rc = TIPC_LINK_UP_EVT;
2266 
2267 		l->peer_session = msg_session(hdr);
2268 		l->in_session = true;
2269 		l->peer_bearer_id = msg_bearer_id(hdr);
2270 		if (l->mtu > msg_max_pkt(hdr))
2271 			l->mtu = msg_max_pkt(hdr);
2272 		break;
2273 
2274 	case STATE_MSG:
2275 		l->rcv_nxt_state = msg_seqno(hdr) + 1;
2276 
2277 		/* Update own tolerance if peer indicates a non-zero value */
2278 		if (in_range(peers_tol, TIPC_MIN_LINK_TOL, TIPC_MAX_LINK_TOL)) {
2279 			l->tolerance = peers_tol;
2280 			l->bc_rcvlink->tolerance = peers_tol;
2281 		}
2282 		/* Update own prio if peer indicates a different value */
2283 		if ((peers_prio != l->priority) &&
2284 		    in_range(peers_prio, 1, TIPC_MAX_LINK_PRI)) {
2285 			l->priority = peers_prio;
2286 			rc = tipc_link_fsm_evt(l, LINK_FAILURE_EVT);
2287 		}
2288 
2289 		l->silent_intv_cnt = 0;
2290 		l->stats.recv_states++;
2291 		if (msg_probe(hdr))
2292 			l->stats.recv_probes++;
2293 
2294 		if (!link_is_up(l)) {
2295 			if (l->state == LINK_ESTABLISHING)
2296 				rc = TIPC_LINK_UP_EVT;
2297 			break;
2298 		}
2299 
2300 		/* Receive Gap ACK blocks from peer if any */
2301 		glen = tipc_get_gap_ack_blks(&ga, l, hdr, true);
2302 
2303 		tipc_mon_rcv(l->net, data + glen, dlen - glen, l->addr,
2304 			     &l->mon_state, l->bearer_id);
2305 
2306 		/* Send NACK if peer has sent pkts we haven't received yet */
2307 		if ((reply || msg_is_keepalive(hdr)) &&
2308 		    more(peers_snd_nxt, rcv_nxt) &&
2309 		    !tipc_link_is_synching(l) &&
2310 		    skb_queue_empty(&l->deferdq))
2311 			rcvgap = peers_snd_nxt - l->rcv_nxt;
2312 		if (rcvgap || reply)
2313 			tipc_link_build_proto_msg(l, STATE_MSG, 0, reply,
2314 						  rcvgap, 0, 0, xmitq);
2315 
2316 		released = tipc_link_advance_transmq(l, l, ack, gap, ga, xmitq,
2317 						     &retransmitted, &rc);
2318 		if (gap)
2319 			l->stats.recv_nacks++;
2320 		if (released || retransmitted)
2321 			tipc_link_update_cwin(l, released, retransmitted);
2322 		if (released)
2323 			tipc_link_advance_backlog(l, xmitq);
2324 		if (unlikely(!skb_queue_empty(&l->wakeupq)))
2325 			link_prepare_wakeup(l);
2326 	}
2327 exit:
2328 	kfree_skb(skb);
2329 	return rc;
2330 }
2331 
2332 /* tipc_link_build_bc_proto_msg() - create broadcast protocol message
2333  */
2334 static bool tipc_link_build_bc_proto_msg(struct tipc_link *l, bool bcast,
2335 					 u16 peers_snd_nxt,
2336 					 struct sk_buff_head *xmitq)
2337 {
2338 	struct sk_buff *skb;
2339 	struct tipc_msg *hdr;
2340 	struct sk_buff *dfrd_skb = skb_peek(&l->deferdq);
2341 	u16 ack = l->rcv_nxt - 1;
2342 	u16 gap_to = peers_snd_nxt - 1;
2343 
2344 	skb = tipc_msg_create(BCAST_PROTOCOL, STATE_MSG, INT_H_SIZE,
2345 			      0, l->addr, tipc_own_addr(l->net), 0, 0, 0);
2346 	if (!skb)
2347 		return false;
2348 	hdr = buf_msg(skb);
2349 	msg_set_last_bcast(hdr, l->bc_sndlink->snd_nxt - 1);
2350 	msg_set_bcast_ack(hdr, ack);
2351 	msg_set_bcgap_after(hdr, ack);
2352 	if (dfrd_skb)
2353 		gap_to = buf_seqno(dfrd_skb) - 1;
2354 	msg_set_bcgap_to(hdr, gap_to);
2355 	msg_set_non_seq(hdr, bcast);
2356 	__skb_queue_tail(xmitq, skb);
2357 	return true;
2358 }
2359 
2360 /* tipc_link_build_bc_init_msg() - synchronize broadcast link endpoints.
2361  *
2362  * Give a newly added peer node the sequence number where it should
2363  * start receiving and acking broadcast packets.
2364  */
2365 static void tipc_link_build_bc_init_msg(struct tipc_link *l,
2366 					struct sk_buff_head *xmitq)
2367 {
2368 	struct sk_buff_head list;
2369 
2370 	__skb_queue_head_init(&list);
2371 	if (!tipc_link_build_bc_proto_msg(l->bc_rcvlink, false, 0, &list))
2372 		return;
2373 	msg_set_bc_ack_invalid(buf_msg(skb_peek(&list)), true);
2374 	tipc_link_xmit(l, &list, xmitq);
2375 }
2376 
2377 /* tipc_link_bc_init_rcv - receive initial broadcast synch data from peer
2378  */
2379 void tipc_link_bc_init_rcv(struct tipc_link *l, struct tipc_msg *hdr)
2380 {
2381 	int mtyp = msg_type(hdr);
2382 	u16 peers_snd_nxt = msg_bc_snd_nxt(hdr);
2383 
2384 	if (link_is_up(l))
2385 		return;
2386 
2387 	if (msg_user(hdr) == BCAST_PROTOCOL) {
2388 		l->rcv_nxt = peers_snd_nxt;
2389 		l->state = LINK_ESTABLISHED;
2390 		return;
2391 	}
2392 
2393 	if (l->peer_caps & TIPC_BCAST_SYNCH)
2394 		return;
2395 
2396 	if (msg_peer_node_is_up(hdr))
2397 		return;
2398 
2399 	/* Compatibility: accept older, less safe initial synch data */
2400 	if ((mtyp == RESET_MSG) || (mtyp == ACTIVATE_MSG))
2401 		l->rcv_nxt = peers_snd_nxt;
2402 }
2403 
2404 /* tipc_link_bc_sync_rcv - update rcv link according to peer's send state
2405  */
2406 int tipc_link_bc_sync_rcv(struct tipc_link *l, struct tipc_msg *hdr,
2407 			  struct sk_buff_head *xmitq)
2408 {
2409 	u16 peers_snd_nxt = msg_bc_snd_nxt(hdr);
2410 	int rc = 0;
2411 
2412 	if (!link_is_up(l))
2413 		return rc;
2414 
2415 	if (!msg_peer_node_is_up(hdr))
2416 		return rc;
2417 
2418 	/* Open when peer acknowledges our bcast init msg (pkt #1) */
2419 	if (msg_ack(hdr))
2420 		l->bc_peer_is_up = true;
2421 
2422 	if (!l->bc_peer_is_up)
2423 		return rc;
2424 
2425 	/* Ignore if peers_snd_nxt goes beyond receive window */
2426 	if (more(peers_snd_nxt, l->rcv_nxt + l->window))
2427 		return rc;
2428 
2429 	l->snd_nxt = peers_snd_nxt;
2430 	if (link_bc_rcv_gap(l))
2431 		rc |= TIPC_LINK_SND_STATE;
2432 
2433 	/* Return now if sender supports nack via STATE messages */
2434 	if (l->peer_caps & TIPC_BCAST_STATE_NACK)
2435 		return rc;
2436 
2437 	/* Otherwise, be backwards compatible */
2438 
2439 	if (!more(peers_snd_nxt, l->rcv_nxt)) {
2440 		l->nack_state = BC_NACK_SND_CONDITIONAL;
2441 		return 0;
2442 	}
2443 
2444 	/* Don't NACK if one was recently sent or peeked */
2445 	if (l->nack_state == BC_NACK_SND_SUPPRESS) {
2446 		l->nack_state = BC_NACK_SND_UNCONDITIONAL;
2447 		return 0;
2448 	}
2449 
2450 	/* Conditionally delay NACK sending until next synch rcv */
2451 	if (l->nack_state == BC_NACK_SND_CONDITIONAL) {
2452 		l->nack_state = BC_NACK_SND_UNCONDITIONAL;
2453 		if ((peers_snd_nxt - l->rcv_nxt) < TIPC_MIN_LINK_WIN)
2454 			return 0;
2455 	}
2456 
2457 	/* Send NACK now but suppress next one */
2458 	tipc_link_build_bc_proto_msg(l, true, peers_snd_nxt, xmitq);
2459 	l->nack_state = BC_NACK_SND_SUPPRESS;
2460 	return 0;
2461 }
2462 
2463 int tipc_link_bc_ack_rcv(struct tipc_link *r, u16 acked, u16 gap,
2464 			 struct tipc_gap_ack_blks *ga,
2465 			 struct sk_buff_head *xmitq,
2466 			 struct sk_buff_head *retrq)
2467 {
2468 	struct tipc_link *l = r->bc_sndlink;
2469 	bool unused = false;
2470 	int rc = 0;
2471 
2472 	if (!link_is_up(r) || !r->bc_peer_is_up)
2473 		return 0;
2474 
2475 	if (gap) {
2476 		l->stats.recv_nacks++;
2477 		r->stats.recv_nacks++;
2478 	}
2479 
2480 	if (less(acked, r->acked) || (acked == r->acked && !gap && !ga))
2481 		return 0;
2482 
2483 	trace_tipc_link_bc_ack(r, acked, gap, &l->transmq);
2484 	tipc_link_advance_transmq(l, r, acked, gap, ga, retrq, &unused, &rc);
2485 
2486 	tipc_link_advance_backlog(l, xmitq);
2487 	if (unlikely(!skb_queue_empty(&l->wakeupq)))
2488 		link_prepare_wakeup(l);
2489 
2490 	return rc;
2491 }
2492 
2493 /* tipc_link_bc_nack_rcv(): receive broadcast nack message
2494  * This function is here for backwards compatibility, since
2495  * no BCAST_PROTOCOL/STATE messages occur from TIPC v2.5.
2496  */
2497 int tipc_link_bc_nack_rcv(struct tipc_link *l, struct sk_buff *skb,
2498 			  struct sk_buff_head *xmitq)
2499 {
2500 	struct tipc_msg *hdr = buf_msg(skb);
2501 	u32 dnode = msg_destnode(hdr);
2502 	int mtyp = msg_type(hdr);
2503 	u16 acked = msg_bcast_ack(hdr);
2504 	u16 from = acked + 1;
2505 	u16 to = msg_bcgap_to(hdr);
2506 	u16 peers_snd_nxt = to + 1;
2507 	int rc = 0;
2508 
2509 	kfree_skb(skb);
2510 
2511 	if (!tipc_link_is_up(l) || !l->bc_peer_is_up)
2512 		return 0;
2513 
2514 	if (mtyp != STATE_MSG)
2515 		return 0;
2516 
2517 	if (dnode == tipc_own_addr(l->net)) {
2518 		rc = tipc_link_bc_ack_rcv(l, acked, to - acked, NULL, xmitq,
2519 					  xmitq);
2520 		l->stats.recv_nacks++;
2521 		return rc;
2522 	}
2523 
2524 	/* Msg for other node => suppress own NACK at next sync if applicable */
2525 	if (more(peers_snd_nxt, l->rcv_nxt) && !less(l->rcv_nxt, from))
2526 		l->nack_state = BC_NACK_SND_SUPPRESS;
2527 
2528 	return 0;
2529 }
2530 
2531 void tipc_link_set_queue_limits(struct tipc_link *l, u32 min_win, u32 max_win)
2532 {
2533 	int max_bulk = TIPC_MAX_PUBL / (l->mtu / ITEM_SIZE);
2534 
2535 	l->min_win = min_win;
2536 	l->ssthresh = max_win;
2537 	l->max_win = max_win;
2538 	l->window = min_win;
2539 	l->backlog[TIPC_LOW_IMPORTANCE].limit      = min_win * 2;
2540 	l->backlog[TIPC_MEDIUM_IMPORTANCE].limit   = min_win * 4;
2541 	l->backlog[TIPC_HIGH_IMPORTANCE].limit     = min_win * 6;
2542 	l->backlog[TIPC_CRITICAL_IMPORTANCE].limit = min_win * 8;
2543 	l->backlog[TIPC_SYSTEM_IMPORTANCE].limit   = max_bulk;
2544 }
2545 
2546 /**
2547  * tipc_link_reset_stats - reset link statistics
2548  * @l: pointer to link
2549  */
2550 void tipc_link_reset_stats(struct tipc_link *l)
2551 {
2552 	memset(&l->stats, 0, sizeof(l->stats));
2553 }
2554 
2555 static void link_print(struct tipc_link *l, const char *str)
2556 {
2557 	struct sk_buff *hskb = skb_peek(&l->transmq);
2558 	u16 head = hskb ? msg_seqno(buf_msg(hskb)) : l->snd_nxt - 1;
2559 	u16 tail = l->snd_nxt - 1;
2560 
2561 	pr_info("%s Link <%s> state %x\n", str, l->name, l->state);
2562 	pr_info("XMTQ: %u [%u-%u], BKLGQ: %u, SNDNX: %u, RCVNX: %u\n",
2563 		skb_queue_len(&l->transmq), head, tail,
2564 		skb_queue_len(&l->backlogq), l->snd_nxt, l->rcv_nxt);
2565 }
2566 
2567 /* Parse and validate nested (link) properties valid for media, bearer and link
2568  */
2569 int tipc_nl_parse_link_prop(struct nlattr *prop, struct nlattr *props[])
2570 {
2571 	int err;
2572 
2573 	err = nla_parse_nested_deprecated(props, TIPC_NLA_PROP_MAX, prop,
2574 					  tipc_nl_prop_policy, NULL);
2575 	if (err)
2576 		return err;
2577 
2578 	if (props[TIPC_NLA_PROP_PRIO]) {
2579 		u32 prio;
2580 
2581 		prio = nla_get_u32(props[TIPC_NLA_PROP_PRIO]);
2582 		if (prio > TIPC_MAX_LINK_PRI)
2583 			return -EINVAL;
2584 	}
2585 
2586 	if (props[TIPC_NLA_PROP_TOL]) {
2587 		u32 tol;
2588 
2589 		tol = nla_get_u32(props[TIPC_NLA_PROP_TOL]);
2590 		if ((tol < TIPC_MIN_LINK_TOL) || (tol > TIPC_MAX_LINK_TOL))
2591 			return -EINVAL;
2592 	}
2593 
2594 	if (props[TIPC_NLA_PROP_WIN]) {
2595 		u32 max_win;
2596 
2597 		max_win = nla_get_u32(props[TIPC_NLA_PROP_WIN]);
2598 		if (max_win < TIPC_DEF_LINK_WIN || max_win > TIPC_MAX_LINK_WIN)
2599 			return -EINVAL;
2600 	}
2601 
2602 	return 0;
2603 }
2604 
2605 static int __tipc_nl_add_stats(struct sk_buff *skb, struct tipc_stats *s)
2606 {
2607 	int i;
2608 	struct nlattr *stats;
2609 
2610 	struct nla_map {
2611 		u32 key;
2612 		u32 val;
2613 	};
2614 
2615 	struct nla_map map[] = {
2616 		{TIPC_NLA_STATS_RX_INFO, 0},
2617 		{TIPC_NLA_STATS_RX_FRAGMENTS, s->recv_fragments},
2618 		{TIPC_NLA_STATS_RX_FRAGMENTED, s->recv_fragmented},
2619 		{TIPC_NLA_STATS_RX_BUNDLES, s->recv_bundles},
2620 		{TIPC_NLA_STATS_RX_BUNDLED, s->recv_bundled},
2621 		{TIPC_NLA_STATS_TX_INFO, 0},
2622 		{TIPC_NLA_STATS_TX_FRAGMENTS, s->sent_fragments},
2623 		{TIPC_NLA_STATS_TX_FRAGMENTED, s->sent_fragmented},
2624 		{TIPC_NLA_STATS_TX_BUNDLES, s->sent_bundles},
2625 		{TIPC_NLA_STATS_TX_BUNDLED, s->sent_bundled},
2626 		{TIPC_NLA_STATS_MSG_PROF_TOT, (s->msg_length_counts) ?
2627 			s->msg_length_counts : 1},
2628 		{TIPC_NLA_STATS_MSG_LEN_CNT, s->msg_length_counts},
2629 		{TIPC_NLA_STATS_MSG_LEN_TOT, s->msg_lengths_total},
2630 		{TIPC_NLA_STATS_MSG_LEN_P0, s->msg_length_profile[0]},
2631 		{TIPC_NLA_STATS_MSG_LEN_P1, s->msg_length_profile[1]},
2632 		{TIPC_NLA_STATS_MSG_LEN_P2, s->msg_length_profile[2]},
2633 		{TIPC_NLA_STATS_MSG_LEN_P3, s->msg_length_profile[3]},
2634 		{TIPC_NLA_STATS_MSG_LEN_P4, s->msg_length_profile[4]},
2635 		{TIPC_NLA_STATS_MSG_LEN_P5, s->msg_length_profile[5]},
2636 		{TIPC_NLA_STATS_MSG_LEN_P6, s->msg_length_profile[6]},
2637 		{TIPC_NLA_STATS_RX_STATES, s->recv_states},
2638 		{TIPC_NLA_STATS_RX_PROBES, s->recv_probes},
2639 		{TIPC_NLA_STATS_RX_NACKS, s->recv_nacks},
2640 		{TIPC_NLA_STATS_RX_DEFERRED, s->deferred_recv},
2641 		{TIPC_NLA_STATS_TX_STATES, s->sent_states},
2642 		{TIPC_NLA_STATS_TX_PROBES, s->sent_probes},
2643 		{TIPC_NLA_STATS_TX_NACKS, s->sent_nacks},
2644 		{TIPC_NLA_STATS_TX_ACKS, s->sent_acks},
2645 		{TIPC_NLA_STATS_RETRANSMITTED, s->retransmitted},
2646 		{TIPC_NLA_STATS_DUPLICATES, s->duplicates},
2647 		{TIPC_NLA_STATS_LINK_CONGS, s->link_congs},
2648 		{TIPC_NLA_STATS_MAX_QUEUE, s->max_queue_sz},
2649 		{TIPC_NLA_STATS_AVG_QUEUE, s->queue_sz_counts ?
2650 			(s->accu_queue_sz / s->queue_sz_counts) : 0}
2651 	};
2652 
2653 	stats = nla_nest_start_noflag(skb, TIPC_NLA_LINK_STATS);
2654 	if (!stats)
2655 		return -EMSGSIZE;
2656 
2657 	for (i = 0; i <  ARRAY_SIZE(map); i++)
2658 		if (nla_put_u32(skb, map[i].key, map[i].val))
2659 			goto msg_full;
2660 
2661 	nla_nest_end(skb, stats);
2662 
2663 	return 0;
2664 msg_full:
2665 	nla_nest_cancel(skb, stats);
2666 
2667 	return -EMSGSIZE;
2668 }
2669 
2670 /* Caller should hold appropriate locks to protect the link */
2671 int __tipc_nl_add_link(struct net *net, struct tipc_nl_msg *msg,
2672 		       struct tipc_link *link, int nlflags)
2673 {
2674 	u32 self = tipc_own_addr(net);
2675 	struct nlattr *attrs;
2676 	struct nlattr *prop;
2677 	void *hdr;
2678 	int err;
2679 
2680 	hdr = genlmsg_put(msg->skb, msg->portid, msg->seq, &tipc_genl_family,
2681 			  nlflags, TIPC_NL_LINK_GET);
2682 	if (!hdr)
2683 		return -EMSGSIZE;
2684 
2685 	attrs = nla_nest_start_noflag(msg->skb, TIPC_NLA_LINK);
2686 	if (!attrs)
2687 		goto msg_full;
2688 
2689 	if (nla_put_string(msg->skb, TIPC_NLA_LINK_NAME, link->name))
2690 		goto attr_msg_full;
2691 	if (nla_put_u32(msg->skb, TIPC_NLA_LINK_DEST, tipc_cluster_mask(self)))
2692 		goto attr_msg_full;
2693 	if (nla_put_u32(msg->skb, TIPC_NLA_LINK_MTU, link->mtu))
2694 		goto attr_msg_full;
2695 	if (nla_put_u32(msg->skb, TIPC_NLA_LINK_RX, link->stats.recv_pkts))
2696 		goto attr_msg_full;
2697 	if (nla_put_u32(msg->skb, TIPC_NLA_LINK_TX, link->stats.sent_pkts))
2698 		goto attr_msg_full;
2699 
2700 	if (tipc_link_is_up(link))
2701 		if (nla_put_flag(msg->skb, TIPC_NLA_LINK_UP))
2702 			goto attr_msg_full;
2703 	if (link->active)
2704 		if (nla_put_flag(msg->skb, TIPC_NLA_LINK_ACTIVE))
2705 			goto attr_msg_full;
2706 
2707 	prop = nla_nest_start_noflag(msg->skb, TIPC_NLA_LINK_PROP);
2708 	if (!prop)
2709 		goto attr_msg_full;
2710 	if (nla_put_u32(msg->skb, TIPC_NLA_PROP_PRIO, link->priority))
2711 		goto prop_msg_full;
2712 	if (nla_put_u32(msg->skb, TIPC_NLA_PROP_TOL, link->tolerance))
2713 		goto prop_msg_full;
2714 	if (nla_put_u32(msg->skb, TIPC_NLA_PROP_WIN,
2715 			link->window))
2716 		goto prop_msg_full;
2717 	if (nla_put_u32(msg->skb, TIPC_NLA_PROP_PRIO, link->priority))
2718 		goto prop_msg_full;
2719 	nla_nest_end(msg->skb, prop);
2720 
2721 	err = __tipc_nl_add_stats(msg->skb, &link->stats);
2722 	if (err)
2723 		goto attr_msg_full;
2724 
2725 	nla_nest_end(msg->skb, attrs);
2726 	genlmsg_end(msg->skb, hdr);
2727 
2728 	return 0;
2729 
2730 prop_msg_full:
2731 	nla_nest_cancel(msg->skb, prop);
2732 attr_msg_full:
2733 	nla_nest_cancel(msg->skb, attrs);
2734 msg_full:
2735 	genlmsg_cancel(msg->skb, hdr);
2736 
2737 	return -EMSGSIZE;
2738 }
2739 
2740 static int __tipc_nl_add_bc_link_stat(struct sk_buff *skb,
2741 				      struct tipc_stats *stats)
2742 {
2743 	int i;
2744 	struct nlattr *nest;
2745 
2746 	struct nla_map {
2747 		__u32 key;
2748 		__u32 val;
2749 	};
2750 
2751 	struct nla_map map[] = {
2752 		{TIPC_NLA_STATS_RX_INFO, stats->recv_pkts},
2753 		{TIPC_NLA_STATS_RX_FRAGMENTS, stats->recv_fragments},
2754 		{TIPC_NLA_STATS_RX_FRAGMENTED, stats->recv_fragmented},
2755 		{TIPC_NLA_STATS_RX_BUNDLES, stats->recv_bundles},
2756 		{TIPC_NLA_STATS_RX_BUNDLED, stats->recv_bundled},
2757 		{TIPC_NLA_STATS_TX_INFO, stats->sent_pkts},
2758 		{TIPC_NLA_STATS_TX_FRAGMENTS, stats->sent_fragments},
2759 		{TIPC_NLA_STATS_TX_FRAGMENTED, stats->sent_fragmented},
2760 		{TIPC_NLA_STATS_TX_BUNDLES, stats->sent_bundles},
2761 		{TIPC_NLA_STATS_TX_BUNDLED, stats->sent_bundled},
2762 		{TIPC_NLA_STATS_RX_NACKS, stats->recv_nacks},
2763 		{TIPC_NLA_STATS_RX_DEFERRED, stats->deferred_recv},
2764 		{TIPC_NLA_STATS_TX_NACKS, stats->sent_nacks},
2765 		{TIPC_NLA_STATS_TX_ACKS, stats->sent_acks},
2766 		{TIPC_NLA_STATS_RETRANSMITTED, stats->retransmitted},
2767 		{TIPC_NLA_STATS_DUPLICATES, stats->duplicates},
2768 		{TIPC_NLA_STATS_LINK_CONGS, stats->link_congs},
2769 		{TIPC_NLA_STATS_MAX_QUEUE, stats->max_queue_sz},
2770 		{TIPC_NLA_STATS_AVG_QUEUE, stats->queue_sz_counts ?
2771 			(stats->accu_queue_sz / stats->queue_sz_counts) : 0}
2772 	};
2773 
2774 	nest = nla_nest_start_noflag(skb, TIPC_NLA_LINK_STATS);
2775 	if (!nest)
2776 		return -EMSGSIZE;
2777 
2778 	for (i = 0; i <  ARRAY_SIZE(map); i++)
2779 		if (nla_put_u32(skb, map[i].key, map[i].val))
2780 			goto msg_full;
2781 
2782 	nla_nest_end(skb, nest);
2783 
2784 	return 0;
2785 msg_full:
2786 	nla_nest_cancel(skb, nest);
2787 
2788 	return -EMSGSIZE;
2789 }
2790 
2791 int tipc_nl_add_bc_link(struct net *net, struct tipc_nl_msg *msg,
2792 			struct tipc_link *bcl)
2793 {
2794 	int err;
2795 	void *hdr;
2796 	struct nlattr *attrs;
2797 	struct nlattr *prop;
2798 	u32 bc_mode = tipc_bcast_get_mode(net);
2799 	u32 bc_ratio = tipc_bcast_get_broadcast_ratio(net);
2800 
2801 	if (!bcl)
2802 		return 0;
2803 
2804 	tipc_bcast_lock(net);
2805 
2806 	hdr = genlmsg_put(msg->skb, msg->portid, msg->seq, &tipc_genl_family,
2807 			  NLM_F_MULTI, TIPC_NL_LINK_GET);
2808 	if (!hdr) {
2809 		tipc_bcast_unlock(net);
2810 		return -EMSGSIZE;
2811 	}
2812 
2813 	attrs = nla_nest_start_noflag(msg->skb, TIPC_NLA_LINK);
2814 	if (!attrs)
2815 		goto msg_full;
2816 
2817 	/* The broadcast link is always up */
2818 	if (nla_put_flag(msg->skb, TIPC_NLA_LINK_UP))
2819 		goto attr_msg_full;
2820 
2821 	if (nla_put_flag(msg->skb, TIPC_NLA_LINK_BROADCAST))
2822 		goto attr_msg_full;
2823 	if (nla_put_string(msg->skb, TIPC_NLA_LINK_NAME, bcl->name))
2824 		goto attr_msg_full;
2825 	if (nla_put_u32(msg->skb, TIPC_NLA_LINK_RX, 0))
2826 		goto attr_msg_full;
2827 	if (nla_put_u32(msg->skb, TIPC_NLA_LINK_TX, 0))
2828 		goto attr_msg_full;
2829 
2830 	prop = nla_nest_start_noflag(msg->skb, TIPC_NLA_LINK_PROP);
2831 	if (!prop)
2832 		goto attr_msg_full;
2833 	if (nla_put_u32(msg->skb, TIPC_NLA_PROP_WIN, bcl->max_win))
2834 		goto prop_msg_full;
2835 	if (nla_put_u32(msg->skb, TIPC_NLA_PROP_BROADCAST, bc_mode))
2836 		goto prop_msg_full;
2837 	if (bc_mode & BCLINK_MODE_SEL)
2838 		if (nla_put_u32(msg->skb, TIPC_NLA_PROP_BROADCAST_RATIO,
2839 				bc_ratio))
2840 			goto prop_msg_full;
2841 	nla_nest_end(msg->skb, prop);
2842 
2843 	err = __tipc_nl_add_bc_link_stat(msg->skb, &bcl->stats);
2844 	if (err)
2845 		goto attr_msg_full;
2846 
2847 	tipc_bcast_unlock(net);
2848 	nla_nest_end(msg->skb, attrs);
2849 	genlmsg_end(msg->skb, hdr);
2850 
2851 	return 0;
2852 
2853 prop_msg_full:
2854 	nla_nest_cancel(msg->skb, prop);
2855 attr_msg_full:
2856 	nla_nest_cancel(msg->skb, attrs);
2857 msg_full:
2858 	tipc_bcast_unlock(net);
2859 	genlmsg_cancel(msg->skb, hdr);
2860 
2861 	return -EMSGSIZE;
2862 }
2863 
2864 void tipc_link_set_tolerance(struct tipc_link *l, u32 tol,
2865 			     struct sk_buff_head *xmitq)
2866 {
2867 	l->tolerance = tol;
2868 	if (l->bc_rcvlink)
2869 		l->bc_rcvlink->tolerance = tol;
2870 	if (link_is_up(l))
2871 		tipc_link_build_proto_msg(l, STATE_MSG, 0, 0, 0, tol, 0, xmitq);
2872 }
2873 
2874 void tipc_link_set_prio(struct tipc_link *l, u32 prio,
2875 			struct sk_buff_head *xmitq)
2876 {
2877 	l->priority = prio;
2878 	tipc_link_build_proto_msg(l, STATE_MSG, 0, 0, 0, 0, prio, xmitq);
2879 }
2880 
2881 void tipc_link_set_abort_limit(struct tipc_link *l, u32 limit)
2882 {
2883 	l->abort_limit = limit;
2884 }
2885 
2886 /**
2887  * tipc_link_dump - dump TIPC link data
2888  * @l: tipc link to be dumped
2889  * @dqueues: bitmask to decide if any link queue to be dumped?
2890  *           - TIPC_DUMP_NONE: don't dump link queues
2891  *           - TIPC_DUMP_TRANSMQ: dump link transmq queue
2892  *           - TIPC_DUMP_BACKLOGQ: dump link backlog queue
2893  *           - TIPC_DUMP_DEFERDQ: dump link deferd queue
2894  *           - TIPC_DUMP_INPUTQ: dump link input queue
2895  *           - TIPC_DUMP_WAKEUP: dump link wakeup queue
2896  *           - TIPC_DUMP_ALL: dump all the link queues above
2897  * @buf: returned buffer of dump data in format
2898  */
2899 int tipc_link_dump(struct tipc_link *l, u16 dqueues, char *buf)
2900 {
2901 	int i = 0;
2902 	size_t sz = (dqueues) ? LINK_LMAX : LINK_LMIN;
2903 	struct sk_buff_head *list;
2904 	struct sk_buff *hskb, *tskb;
2905 	u32 len;
2906 
2907 	if (!l) {
2908 		i += scnprintf(buf, sz, "link data: (null)\n");
2909 		return i;
2910 	}
2911 
2912 	i += scnprintf(buf, sz, "link data: %x", l->addr);
2913 	i += scnprintf(buf + i, sz - i, " %x", l->state);
2914 	i += scnprintf(buf + i, sz - i, " %u", l->in_session);
2915 	i += scnprintf(buf + i, sz - i, " %u", l->session);
2916 	i += scnprintf(buf + i, sz - i, " %u", l->peer_session);
2917 	i += scnprintf(buf + i, sz - i, " %u", l->snd_nxt);
2918 	i += scnprintf(buf + i, sz - i, " %u", l->rcv_nxt);
2919 	i += scnprintf(buf + i, sz - i, " %u", l->snd_nxt_state);
2920 	i += scnprintf(buf + i, sz - i, " %u", l->rcv_nxt_state);
2921 	i += scnprintf(buf + i, sz - i, " %x", l->peer_caps);
2922 	i += scnprintf(buf + i, sz - i, " %u", l->silent_intv_cnt);
2923 	i += scnprintf(buf + i, sz - i, " %u", l->rst_cnt);
2924 	i += scnprintf(buf + i, sz - i, " %u", 0);
2925 	i += scnprintf(buf + i, sz - i, " %u", 0);
2926 	i += scnprintf(buf + i, sz - i, " %u", l->acked);
2927 
2928 	list = &l->transmq;
2929 	len = skb_queue_len(list);
2930 	hskb = skb_peek(list);
2931 	tskb = skb_peek_tail(list);
2932 	i += scnprintf(buf + i, sz - i, " | %u %u %u", len,
2933 		       (hskb) ? msg_seqno(buf_msg(hskb)) : 0,
2934 		       (tskb) ? msg_seqno(buf_msg(tskb)) : 0);
2935 
2936 	list = &l->deferdq;
2937 	len = skb_queue_len(list);
2938 	hskb = skb_peek(list);
2939 	tskb = skb_peek_tail(list);
2940 	i += scnprintf(buf + i, sz - i, " | %u %u %u", len,
2941 		       (hskb) ? msg_seqno(buf_msg(hskb)) : 0,
2942 		       (tskb) ? msg_seqno(buf_msg(tskb)) : 0);
2943 
2944 	list = &l->backlogq;
2945 	len = skb_queue_len(list);
2946 	hskb = skb_peek(list);
2947 	tskb = skb_peek_tail(list);
2948 	i += scnprintf(buf + i, sz - i, " | %u %u %u", len,
2949 		       (hskb) ? msg_seqno(buf_msg(hskb)) : 0,
2950 		       (tskb) ? msg_seqno(buf_msg(tskb)) : 0);
2951 
2952 	list = l->inputq;
2953 	len = skb_queue_len(list);
2954 	hskb = skb_peek(list);
2955 	tskb = skb_peek_tail(list);
2956 	i += scnprintf(buf + i, sz - i, " | %u %u %u\n", len,
2957 		       (hskb) ? msg_seqno(buf_msg(hskb)) : 0,
2958 		       (tskb) ? msg_seqno(buf_msg(tskb)) : 0);
2959 
2960 	if (dqueues & TIPC_DUMP_TRANSMQ) {
2961 		i += scnprintf(buf + i, sz - i, "transmq: ");
2962 		i += tipc_list_dump(&l->transmq, false, buf + i);
2963 	}
2964 	if (dqueues & TIPC_DUMP_BACKLOGQ) {
2965 		i += scnprintf(buf + i, sz - i,
2966 			       "backlogq: <%u %u %u %u %u>, ",
2967 			       l->backlog[TIPC_LOW_IMPORTANCE].len,
2968 			       l->backlog[TIPC_MEDIUM_IMPORTANCE].len,
2969 			       l->backlog[TIPC_HIGH_IMPORTANCE].len,
2970 			       l->backlog[TIPC_CRITICAL_IMPORTANCE].len,
2971 			       l->backlog[TIPC_SYSTEM_IMPORTANCE].len);
2972 		i += tipc_list_dump(&l->backlogq, false, buf + i);
2973 	}
2974 	if (dqueues & TIPC_DUMP_DEFERDQ) {
2975 		i += scnprintf(buf + i, sz - i, "deferdq: ");
2976 		i += tipc_list_dump(&l->deferdq, false, buf + i);
2977 	}
2978 	if (dqueues & TIPC_DUMP_INPUTQ) {
2979 		i += scnprintf(buf + i, sz - i, "inputq: ");
2980 		i += tipc_list_dump(l->inputq, false, buf + i);
2981 	}
2982 	if (dqueues & TIPC_DUMP_WAKEUP) {
2983 		i += scnprintf(buf + i, sz - i, "wakeup: ");
2984 		i += tipc_list_dump(&l->wakeupq, false, buf + i);
2985 	}
2986 
2987 	return i;
2988 }
2989