xref: /openbmc/linux/net/tipc/link.c (revision 3a83e4e6)
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  */
124 struct tipc_link {
125 	u32 addr;
126 	char name[TIPC_MAX_LINK_NAME];
127 	struct net *net;
128 
129 	/* Management and link supervision data */
130 	u16 peer_session;
131 	u16 session;
132 	u16 snd_nxt_state;
133 	u16 rcv_nxt_state;
134 	u32 peer_bearer_id;
135 	u32 bearer_id;
136 	u32 tolerance;
137 	u32 abort_limit;
138 	u32 state;
139 	u16 peer_caps;
140 	bool in_session;
141 	bool active;
142 	u32 silent_intv_cnt;
143 	char if_name[TIPC_MAX_IF_NAME];
144 	u32 priority;
145 	char net_plane;
146 	struct tipc_mon_state mon_state;
147 	u16 rst_cnt;
148 
149 	/* Failover/synch */
150 	u16 drop_point;
151 	struct sk_buff *failover_reasm_skb;
152 	struct sk_buff_head failover_deferdq;
153 
154 	/* Max packet negotiation */
155 	u16 mtu;
156 	u16 advertised_mtu;
157 
158 	/* Sending */
159 	struct sk_buff_head transmq;
160 	struct sk_buff_head backlogq;
161 	struct {
162 		u16 len;
163 		u16 limit;
164 		struct sk_buff *target_bskb;
165 	} backlog[5];
166 	u16 snd_nxt;
167 
168 	/* Reception */
169 	u16 rcv_nxt;
170 	u32 rcv_unacked;
171 	struct sk_buff_head deferdq;
172 	struct sk_buff_head *inputq;
173 	struct sk_buff_head *namedq;
174 
175 	/* Congestion handling */
176 	struct sk_buff_head wakeupq;
177 	u16 window;
178 	u16 min_win;
179 	u16 ssthresh;
180 	u16 max_win;
181 	u16 cong_acks;
182 	u16 checkpoint;
183 
184 	/* Fragmentation/reassembly */
185 	struct sk_buff *reasm_buf;
186 	struct sk_buff *reasm_tnlmsg;
187 
188 	/* Broadcast */
189 	u16 ackers;
190 	u16 acked;
191 	u16 last_gap;
192 	struct tipc_gap_ack_blks *last_ga;
193 	struct tipc_link *bc_rcvlink;
194 	struct tipc_link *bc_sndlink;
195 	u8 nack_state;
196 	bool bc_peer_is_up;
197 
198 	/* Statistics */
199 	struct tipc_stats stats;
200 };
201 
202 /*
203  * Error message prefixes
204  */
205 static const char *link_co_err = "Link tunneling error, ";
206 static const char *link_rst_msg = "Resetting link ";
207 
208 /* Send states for broadcast NACKs
209  */
210 enum {
211 	BC_NACK_SND_CONDITIONAL,
212 	BC_NACK_SND_UNCONDITIONAL,
213 	BC_NACK_SND_SUPPRESS,
214 };
215 
216 #define TIPC_BC_RETR_LIM  (jiffies + msecs_to_jiffies(10))
217 #define TIPC_UC_RETR_TIME (jiffies + msecs_to_jiffies(1))
218 
219 /*
220  * Interval between NACKs when packets arrive out of order
221  */
222 #define TIPC_NACK_INTV (TIPC_MIN_LINK_WIN * 2)
223 
224 /* Link FSM states:
225  */
226 enum {
227 	LINK_ESTABLISHED     = 0xe,
228 	LINK_ESTABLISHING    = 0xe  << 4,
229 	LINK_RESET           = 0x1  << 8,
230 	LINK_RESETTING       = 0x2  << 12,
231 	LINK_PEER_RESET      = 0xd  << 16,
232 	LINK_FAILINGOVER     = 0xf  << 20,
233 	LINK_SYNCHING        = 0xc  << 24
234 };
235 
236 /* Link FSM state checking routines
237  */
238 static int link_is_up(struct tipc_link *l)
239 {
240 	return l->state & (LINK_ESTABLISHED | LINK_SYNCHING);
241 }
242 
243 static int tipc_link_proto_rcv(struct tipc_link *l, struct sk_buff *skb,
244 			       struct sk_buff_head *xmitq);
245 static void tipc_link_build_proto_msg(struct tipc_link *l, int mtyp, bool probe,
246 				      bool probe_reply, u16 rcvgap,
247 				      int tolerance, int priority,
248 				      struct sk_buff_head *xmitq);
249 static void link_print(struct tipc_link *l, const char *str);
250 static int tipc_link_build_nack_msg(struct tipc_link *l,
251 				    struct sk_buff_head *xmitq);
252 static void tipc_link_build_bc_init_msg(struct tipc_link *l,
253 					struct sk_buff_head *xmitq);
254 static u8 __tipc_build_gap_ack_blks(struct tipc_gap_ack_blks *ga,
255 				    struct tipc_link *l, u8 start_index);
256 static u16 tipc_build_gap_ack_blks(struct tipc_link *l, struct tipc_msg *hdr);
257 static int tipc_link_advance_transmq(struct tipc_link *l, struct tipc_link *r,
258 				     u16 acked, u16 gap,
259 				     struct tipc_gap_ack_blks *ga,
260 				     struct sk_buff_head *xmitq,
261 				     bool *retransmitted, int *rc);
262 static void tipc_link_update_cwin(struct tipc_link *l, int released,
263 				  bool retransmitted);
264 /*
265  *  Simple non-static link routines (i.e. referenced outside this file)
266  */
267 bool tipc_link_is_up(struct tipc_link *l)
268 {
269 	return link_is_up(l);
270 }
271 
272 bool tipc_link_peer_is_down(struct tipc_link *l)
273 {
274 	return l->state == LINK_PEER_RESET;
275 }
276 
277 bool tipc_link_is_reset(struct tipc_link *l)
278 {
279 	return l->state & (LINK_RESET | LINK_FAILINGOVER | LINK_ESTABLISHING);
280 }
281 
282 bool tipc_link_is_establishing(struct tipc_link *l)
283 {
284 	return l->state == LINK_ESTABLISHING;
285 }
286 
287 bool tipc_link_is_synching(struct tipc_link *l)
288 {
289 	return l->state == LINK_SYNCHING;
290 }
291 
292 bool tipc_link_is_failingover(struct tipc_link *l)
293 {
294 	return l->state == LINK_FAILINGOVER;
295 }
296 
297 bool tipc_link_is_blocked(struct tipc_link *l)
298 {
299 	return l->state & (LINK_RESETTING | LINK_PEER_RESET | LINK_FAILINGOVER);
300 }
301 
302 static bool link_is_bc_sndlink(struct tipc_link *l)
303 {
304 	return !l->bc_sndlink;
305 }
306 
307 static bool link_is_bc_rcvlink(struct tipc_link *l)
308 {
309 	return ((l->bc_rcvlink == l) && !link_is_bc_sndlink(l));
310 }
311 
312 void tipc_link_set_active(struct tipc_link *l, bool active)
313 {
314 	l->active = active;
315 }
316 
317 u32 tipc_link_id(struct tipc_link *l)
318 {
319 	return l->peer_bearer_id << 16 | l->bearer_id;
320 }
321 
322 int tipc_link_min_win(struct tipc_link *l)
323 {
324 	return l->min_win;
325 }
326 
327 int tipc_link_max_win(struct tipc_link *l)
328 {
329 	return l->max_win;
330 }
331 
332 int tipc_link_prio(struct tipc_link *l)
333 {
334 	return l->priority;
335 }
336 
337 unsigned long tipc_link_tolerance(struct tipc_link *l)
338 {
339 	return l->tolerance;
340 }
341 
342 struct sk_buff_head *tipc_link_inputq(struct tipc_link *l)
343 {
344 	return l->inputq;
345 }
346 
347 char tipc_link_plane(struct tipc_link *l)
348 {
349 	return l->net_plane;
350 }
351 
352 void tipc_link_update_caps(struct tipc_link *l, u16 capabilities)
353 {
354 	l->peer_caps = capabilities;
355 }
356 
357 void tipc_link_add_bc_peer(struct tipc_link *snd_l,
358 			   struct tipc_link *uc_l,
359 			   struct sk_buff_head *xmitq)
360 {
361 	struct tipc_link *rcv_l = uc_l->bc_rcvlink;
362 
363 	snd_l->ackers++;
364 	rcv_l->acked = snd_l->snd_nxt - 1;
365 	snd_l->state = LINK_ESTABLISHED;
366 	tipc_link_build_bc_init_msg(uc_l, xmitq);
367 }
368 
369 void tipc_link_remove_bc_peer(struct tipc_link *snd_l,
370 			      struct tipc_link *rcv_l,
371 			      struct sk_buff_head *xmitq)
372 {
373 	u16 ack = snd_l->snd_nxt - 1;
374 
375 	snd_l->ackers--;
376 	rcv_l->bc_peer_is_up = true;
377 	rcv_l->state = LINK_ESTABLISHED;
378 	tipc_link_bc_ack_rcv(rcv_l, ack, 0, NULL, xmitq, NULL);
379 	trace_tipc_link_reset(rcv_l, TIPC_DUMP_ALL, "bclink removed!");
380 	tipc_link_reset(rcv_l);
381 	rcv_l->state = LINK_RESET;
382 	if (!snd_l->ackers) {
383 		trace_tipc_link_reset(snd_l, TIPC_DUMP_ALL, "zero ackers!");
384 		tipc_link_reset(snd_l);
385 		snd_l->state = LINK_RESET;
386 		__skb_queue_purge(xmitq);
387 	}
388 }
389 
390 int tipc_link_bc_peers(struct tipc_link *l)
391 {
392 	return l->ackers;
393 }
394 
395 static u16 link_bc_rcv_gap(struct tipc_link *l)
396 {
397 	struct sk_buff *skb = skb_peek(&l->deferdq);
398 	u16 gap = 0;
399 
400 	if (more(l->snd_nxt, l->rcv_nxt))
401 		gap = l->snd_nxt - l->rcv_nxt;
402 	if (skb)
403 		gap = buf_seqno(skb) - l->rcv_nxt;
404 	return gap;
405 }
406 
407 void tipc_link_set_mtu(struct tipc_link *l, int mtu)
408 {
409 	l->mtu = mtu;
410 }
411 
412 int tipc_link_mtu(struct tipc_link *l)
413 {
414 	return l->mtu;
415 }
416 
417 int tipc_link_mss(struct tipc_link *l)
418 {
419 #ifdef CONFIG_TIPC_CRYPTO
420 	return l->mtu - INT_H_SIZE - EMSG_OVERHEAD;
421 #else
422 	return l->mtu - INT_H_SIZE;
423 #endif
424 }
425 
426 u16 tipc_link_rcv_nxt(struct tipc_link *l)
427 {
428 	return l->rcv_nxt;
429 }
430 
431 u16 tipc_link_acked(struct tipc_link *l)
432 {
433 	return l->acked;
434 }
435 
436 char *tipc_link_name(struct tipc_link *l)
437 {
438 	return l->name;
439 }
440 
441 u32 tipc_link_state(struct tipc_link *l)
442 {
443 	return l->state;
444 }
445 
446 /**
447  * tipc_link_create - create a new link
448  * @net: pointer to associated network namespace
449  * @if_name: associated interface name
450  * @bearer_id: id (index) of associated bearer
451  * @tolerance: link tolerance to be used by link
452  * @net_plane: network plane (A,B,c..) this link belongs to
453  * @mtu: mtu to be advertised by link
454  * @priority: priority to be used by link
455  * @min_win: minimal send window to be used by link
456  * @max_win: maximal send window to be used by link
457  * @session: session to be used by link
458  * @ownnode: identity of own node
459  * @peer: node id of peer node
460  * @peer_caps: bitmap describing peer node capabilities
461  * @bc_sndlink: the namespace global link used for broadcast sending
462  * @bc_rcvlink: the peer specific link used for broadcast reception
463  * @inputq: queue to put messages ready for delivery
464  * @namedq: queue to put binding table update messages ready for delivery
465  * @link: return value, pointer to put the created link
466  *
467  * Returns true if link was created, otherwise false
468  */
469 bool tipc_link_create(struct net *net, char *if_name, int bearer_id,
470 		      int tolerance, char net_plane, u32 mtu, int priority,
471 		      u32 min_win, u32 max_win, u32 session, u32 self,
472 		      u32 peer, u8 *peer_id, u16 peer_caps,
473 		      struct tipc_link *bc_sndlink,
474 		      struct tipc_link *bc_rcvlink,
475 		      struct sk_buff_head *inputq,
476 		      struct sk_buff_head *namedq,
477 		      struct tipc_link **link)
478 {
479 	char peer_str[NODE_ID_STR_LEN] = {0,};
480 	char self_str[NODE_ID_STR_LEN] = {0,};
481 	struct tipc_link *l;
482 
483 	l = kzalloc(sizeof(*l), GFP_ATOMIC);
484 	if (!l)
485 		return false;
486 	*link = l;
487 	l->session = session;
488 
489 	/* Set link name for unicast links only */
490 	if (peer_id) {
491 		tipc_nodeid2string(self_str, tipc_own_id(net));
492 		if (strlen(self_str) > 16)
493 			sprintf(self_str, "%x", self);
494 		tipc_nodeid2string(peer_str, peer_id);
495 		if (strlen(peer_str) > 16)
496 			sprintf(peer_str, "%x", peer);
497 	}
498 	/* Peer i/f name will be completed by reset/activate message */
499 	snprintf(l->name, sizeof(l->name), "%s:%s-%s:unknown",
500 		 self_str, if_name, peer_str);
501 
502 	strcpy(l->if_name, if_name);
503 	l->addr = peer;
504 	l->peer_caps = peer_caps;
505 	l->net = net;
506 	l->in_session = false;
507 	l->bearer_id = bearer_id;
508 	l->tolerance = tolerance;
509 	if (bc_rcvlink)
510 		bc_rcvlink->tolerance = tolerance;
511 	l->net_plane = net_plane;
512 	l->advertised_mtu = mtu;
513 	l->mtu = mtu;
514 	l->priority = priority;
515 	tipc_link_set_queue_limits(l, min_win, max_win);
516 	l->ackers = 1;
517 	l->bc_sndlink = bc_sndlink;
518 	l->bc_rcvlink = bc_rcvlink;
519 	l->inputq = inputq;
520 	l->namedq = namedq;
521 	l->state = LINK_RESETTING;
522 	__skb_queue_head_init(&l->transmq);
523 	__skb_queue_head_init(&l->backlogq);
524 	__skb_queue_head_init(&l->deferdq);
525 	__skb_queue_head_init(&l->failover_deferdq);
526 	skb_queue_head_init(&l->wakeupq);
527 	skb_queue_head_init(l->inputq);
528 	return true;
529 }
530 
531 /**
532  * tipc_link_bc_create - create new link to be used for broadcast
533  * @net: pointer to associated network namespace
534  * @mtu: mtu to be used initially if no peers
535  * @window: send window to be used
536  * @inputq: queue to put messages ready for delivery
537  * @namedq: queue to put binding table update messages ready for delivery
538  * @link: return value, pointer to put the created link
539  *
540  * Returns true if link was created, otherwise false
541  */
542 bool tipc_link_bc_create(struct net *net, u32 ownnode, u32 peer, u8 *peer_id,
543 			 int mtu, u32 min_win, u32 max_win, u16 peer_caps,
544 			 struct sk_buff_head *inputq,
545 			 struct sk_buff_head *namedq,
546 			 struct tipc_link *bc_sndlink,
547 			 struct tipc_link **link)
548 {
549 	struct tipc_link *l;
550 
551 	if (!tipc_link_create(net, "", MAX_BEARERS, 0, 'Z', mtu, 0, min_win,
552 			      max_win, 0, ownnode, peer, NULL, peer_caps,
553 			      bc_sndlink, NULL, inputq, namedq, link))
554 		return false;
555 
556 	l = *link;
557 	if (peer_id) {
558 		char peer_str[NODE_ID_STR_LEN] = {0,};
559 
560 		tipc_nodeid2string(peer_str, peer_id);
561 		if (strlen(peer_str) > 16)
562 			sprintf(peer_str, "%x", peer);
563 		/* Broadcast receiver link name: "broadcast-link:<peer>" */
564 		snprintf(l->name, sizeof(l->name), "%s:%s", tipc_bclink_name,
565 			 peer_str);
566 	} else {
567 		strcpy(l->name, tipc_bclink_name);
568 	}
569 	trace_tipc_link_reset(l, TIPC_DUMP_ALL, "bclink created!");
570 	tipc_link_reset(l);
571 	l->state = LINK_RESET;
572 	l->ackers = 0;
573 	l->bc_rcvlink = l;
574 
575 	/* Broadcast send link is always up */
576 	if (link_is_bc_sndlink(l))
577 		l->state = LINK_ESTABLISHED;
578 
579 	/* Disable replicast if even a single peer doesn't support it */
580 	if (link_is_bc_rcvlink(l) && !(peer_caps & TIPC_BCAST_RCAST))
581 		tipc_bcast_toggle_rcast(net, false);
582 
583 	return true;
584 }
585 
586 /**
587  * tipc_link_fsm_evt - link finite state machine
588  * @l: pointer to link
589  * @evt: state machine event to be processed
590  */
591 int tipc_link_fsm_evt(struct tipc_link *l, int evt)
592 {
593 	int rc = 0;
594 	int old_state = l->state;
595 
596 	switch (l->state) {
597 	case LINK_RESETTING:
598 		switch (evt) {
599 		case LINK_PEER_RESET_EVT:
600 			l->state = LINK_PEER_RESET;
601 			break;
602 		case LINK_RESET_EVT:
603 			l->state = LINK_RESET;
604 			break;
605 		case LINK_FAILURE_EVT:
606 		case LINK_FAILOVER_BEGIN_EVT:
607 		case LINK_ESTABLISH_EVT:
608 		case LINK_FAILOVER_END_EVT:
609 		case LINK_SYNCH_BEGIN_EVT:
610 		case LINK_SYNCH_END_EVT:
611 		default:
612 			goto illegal_evt;
613 		}
614 		break;
615 	case LINK_RESET:
616 		switch (evt) {
617 		case LINK_PEER_RESET_EVT:
618 			l->state = LINK_ESTABLISHING;
619 			break;
620 		case LINK_FAILOVER_BEGIN_EVT:
621 			l->state = LINK_FAILINGOVER;
622 		case LINK_FAILURE_EVT:
623 		case LINK_RESET_EVT:
624 		case LINK_ESTABLISH_EVT:
625 		case LINK_FAILOVER_END_EVT:
626 			break;
627 		case LINK_SYNCH_BEGIN_EVT:
628 		case LINK_SYNCH_END_EVT:
629 		default:
630 			goto illegal_evt;
631 		}
632 		break;
633 	case LINK_PEER_RESET:
634 		switch (evt) {
635 		case LINK_RESET_EVT:
636 			l->state = LINK_ESTABLISHING;
637 			break;
638 		case LINK_PEER_RESET_EVT:
639 		case LINK_ESTABLISH_EVT:
640 		case LINK_FAILURE_EVT:
641 			break;
642 		case LINK_SYNCH_BEGIN_EVT:
643 		case LINK_SYNCH_END_EVT:
644 		case LINK_FAILOVER_BEGIN_EVT:
645 		case LINK_FAILOVER_END_EVT:
646 		default:
647 			goto illegal_evt;
648 		}
649 		break;
650 	case LINK_FAILINGOVER:
651 		switch (evt) {
652 		case LINK_FAILOVER_END_EVT:
653 			l->state = LINK_RESET;
654 			break;
655 		case LINK_PEER_RESET_EVT:
656 		case LINK_RESET_EVT:
657 		case LINK_ESTABLISH_EVT:
658 		case LINK_FAILURE_EVT:
659 			break;
660 		case LINK_FAILOVER_BEGIN_EVT:
661 		case LINK_SYNCH_BEGIN_EVT:
662 		case LINK_SYNCH_END_EVT:
663 		default:
664 			goto illegal_evt;
665 		}
666 		break;
667 	case LINK_ESTABLISHING:
668 		switch (evt) {
669 		case LINK_ESTABLISH_EVT:
670 			l->state = LINK_ESTABLISHED;
671 			break;
672 		case LINK_FAILOVER_BEGIN_EVT:
673 			l->state = LINK_FAILINGOVER;
674 			break;
675 		case LINK_RESET_EVT:
676 			l->state = LINK_RESET;
677 			break;
678 		case LINK_FAILURE_EVT:
679 		case LINK_PEER_RESET_EVT:
680 		case LINK_SYNCH_BEGIN_EVT:
681 		case LINK_FAILOVER_END_EVT:
682 			break;
683 		case LINK_SYNCH_END_EVT:
684 		default:
685 			goto illegal_evt;
686 		}
687 		break;
688 	case LINK_ESTABLISHED:
689 		switch (evt) {
690 		case LINK_PEER_RESET_EVT:
691 			l->state = LINK_PEER_RESET;
692 			rc |= TIPC_LINK_DOWN_EVT;
693 			break;
694 		case LINK_FAILURE_EVT:
695 			l->state = LINK_RESETTING;
696 			rc |= TIPC_LINK_DOWN_EVT;
697 			break;
698 		case LINK_RESET_EVT:
699 			l->state = LINK_RESET;
700 			break;
701 		case LINK_ESTABLISH_EVT:
702 		case LINK_SYNCH_END_EVT:
703 			break;
704 		case LINK_SYNCH_BEGIN_EVT:
705 			l->state = LINK_SYNCHING;
706 			break;
707 		case LINK_FAILOVER_BEGIN_EVT:
708 		case LINK_FAILOVER_END_EVT:
709 		default:
710 			goto illegal_evt;
711 		}
712 		break;
713 	case LINK_SYNCHING:
714 		switch (evt) {
715 		case LINK_PEER_RESET_EVT:
716 			l->state = LINK_PEER_RESET;
717 			rc |= TIPC_LINK_DOWN_EVT;
718 			break;
719 		case LINK_FAILURE_EVT:
720 			l->state = LINK_RESETTING;
721 			rc |= TIPC_LINK_DOWN_EVT;
722 			break;
723 		case LINK_RESET_EVT:
724 			l->state = LINK_RESET;
725 			break;
726 		case LINK_ESTABLISH_EVT:
727 		case LINK_SYNCH_BEGIN_EVT:
728 			break;
729 		case LINK_SYNCH_END_EVT:
730 			l->state = LINK_ESTABLISHED;
731 			break;
732 		case LINK_FAILOVER_BEGIN_EVT:
733 		case LINK_FAILOVER_END_EVT:
734 		default:
735 			goto illegal_evt;
736 		}
737 		break;
738 	default:
739 		pr_err("Unknown FSM state %x in %s\n", l->state, l->name);
740 	}
741 	trace_tipc_link_fsm(l->name, old_state, l->state, evt);
742 	return rc;
743 illegal_evt:
744 	pr_err("Illegal FSM event %x in state %x on link %s\n",
745 	       evt, l->state, l->name);
746 	trace_tipc_link_fsm(l->name, old_state, l->state, evt);
747 	return rc;
748 }
749 
750 /* link_profile_stats - update statistical profiling of traffic
751  */
752 static void link_profile_stats(struct tipc_link *l)
753 {
754 	struct sk_buff *skb;
755 	struct tipc_msg *msg;
756 	int length;
757 
758 	/* Update counters used in statistical profiling of send traffic */
759 	l->stats.accu_queue_sz += skb_queue_len(&l->transmq);
760 	l->stats.queue_sz_counts++;
761 
762 	skb = skb_peek(&l->transmq);
763 	if (!skb)
764 		return;
765 	msg = buf_msg(skb);
766 	length = msg_size(msg);
767 
768 	if (msg_user(msg) == MSG_FRAGMENTER) {
769 		if (msg_type(msg) != FIRST_FRAGMENT)
770 			return;
771 		length = msg_size(msg_inner_hdr(msg));
772 	}
773 	l->stats.msg_lengths_total += length;
774 	l->stats.msg_length_counts++;
775 	if (length <= 64)
776 		l->stats.msg_length_profile[0]++;
777 	else if (length <= 256)
778 		l->stats.msg_length_profile[1]++;
779 	else if (length <= 1024)
780 		l->stats.msg_length_profile[2]++;
781 	else if (length <= 4096)
782 		l->stats.msg_length_profile[3]++;
783 	else if (length <= 16384)
784 		l->stats.msg_length_profile[4]++;
785 	else if (length <= 32768)
786 		l->stats.msg_length_profile[5]++;
787 	else
788 		l->stats.msg_length_profile[6]++;
789 }
790 
791 /**
792  * tipc_link_too_silent - check if link is "too silent"
793  * @l: tipc link to be checked
794  *
795  * Returns true if the link 'silent_intv_cnt' is about to reach the
796  * 'abort_limit' value, otherwise false
797  */
798 bool tipc_link_too_silent(struct tipc_link *l)
799 {
800 	return (l->silent_intv_cnt + 2 > l->abort_limit);
801 }
802 
803 /* tipc_link_timeout - perform periodic task as instructed from node timeout
804  */
805 int tipc_link_timeout(struct tipc_link *l, struct sk_buff_head *xmitq)
806 {
807 	int mtyp = 0;
808 	int rc = 0;
809 	bool state = false;
810 	bool probe = false;
811 	bool setup = false;
812 	u16 bc_snt = l->bc_sndlink->snd_nxt - 1;
813 	u16 bc_acked = l->bc_rcvlink->acked;
814 	struct tipc_mon_state *mstate = &l->mon_state;
815 
816 	trace_tipc_link_timeout(l, TIPC_DUMP_NONE, " ");
817 	trace_tipc_link_too_silent(l, TIPC_DUMP_ALL, " ");
818 	switch (l->state) {
819 	case LINK_ESTABLISHED:
820 	case LINK_SYNCHING:
821 		mtyp = STATE_MSG;
822 		link_profile_stats(l);
823 		tipc_mon_get_state(l->net, l->addr, mstate, l->bearer_id);
824 		if (mstate->reset || (l->silent_intv_cnt > l->abort_limit))
825 			return tipc_link_fsm_evt(l, LINK_FAILURE_EVT);
826 		state = bc_acked != bc_snt;
827 		state |= l->bc_rcvlink->rcv_unacked;
828 		state |= l->rcv_unacked;
829 		state |= !skb_queue_empty(&l->transmq);
830 		probe = mstate->probing;
831 		probe |= l->silent_intv_cnt;
832 		if (probe || mstate->monitoring)
833 			l->silent_intv_cnt++;
834 		probe |= !skb_queue_empty(&l->deferdq);
835 		if (l->snd_nxt == l->checkpoint) {
836 			tipc_link_update_cwin(l, 0, 0);
837 			probe = true;
838 		}
839 		l->checkpoint = l->snd_nxt;
840 		break;
841 	case LINK_RESET:
842 		setup = l->rst_cnt++ <= 4;
843 		setup |= !(l->rst_cnt % 16);
844 		mtyp = RESET_MSG;
845 		break;
846 	case LINK_ESTABLISHING:
847 		setup = true;
848 		mtyp = ACTIVATE_MSG;
849 		break;
850 	case LINK_PEER_RESET:
851 	case LINK_RESETTING:
852 	case LINK_FAILINGOVER:
853 		break;
854 	default:
855 		break;
856 	}
857 
858 	if (state || probe || setup)
859 		tipc_link_build_proto_msg(l, mtyp, probe, 0, 0, 0, 0, xmitq);
860 
861 	return rc;
862 }
863 
864 /**
865  * link_schedule_user - schedule a message sender for wakeup after congestion
866  * @l: congested link
867  * @hdr: header of message that is being sent
868  * Create pseudo msg to send back to user when congestion abates
869  */
870 static int link_schedule_user(struct tipc_link *l, struct tipc_msg *hdr)
871 {
872 	u32 dnode = tipc_own_addr(l->net);
873 	u32 dport = msg_origport(hdr);
874 	struct sk_buff *skb;
875 
876 	/* Create and schedule wakeup pseudo message */
877 	skb = tipc_msg_create(SOCK_WAKEUP, 0, INT_H_SIZE, 0,
878 			      dnode, l->addr, dport, 0, 0);
879 	if (!skb)
880 		return -ENOBUFS;
881 	msg_set_dest_droppable(buf_msg(skb), true);
882 	TIPC_SKB_CB(skb)->chain_imp = msg_importance(hdr);
883 	skb_queue_tail(&l->wakeupq, skb);
884 	l->stats.link_congs++;
885 	trace_tipc_link_conges(l, TIPC_DUMP_ALL, "wakeup scheduled!");
886 	return -ELINKCONG;
887 }
888 
889 /**
890  * link_prepare_wakeup - prepare users for wakeup after congestion
891  * @l: congested link
892  * Wake up a number of waiting users, as permitted by available space
893  * in the send queue
894  */
895 static void link_prepare_wakeup(struct tipc_link *l)
896 {
897 	struct sk_buff_head *wakeupq = &l->wakeupq;
898 	struct sk_buff_head *inputq = l->inputq;
899 	struct sk_buff *skb, *tmp;
900 	struct sk_buff_head tmpq;
901 	int avail[5] = {0,};
902 	int imp = 0;
903 
904 	__skb_queue_head_init(&tmpq);
905 
906 	for (; imp <= TIPC_SYSTEM_IMPORTANCE; imp++)
907 		avail[imp] = l->backlog[imp].limit - l->backlog[imp].len;
908 
909 	skb_queue_walk_safe(wakeupq, skb, tmp) {
910 		imp = TIPC_SKB_CB(skb)->chain_imp;
911 		if (avail[imp] <= 0)
912 			continue;
913 		avail[imp]--;
914 		__skb_unlink(skb, wakeupq);
915 		__skb_queue_tail(&tmpq, skb);
916 	}
917 
918 	spin_lock_bh(&inputq->lock);
919 	skb_queue_splice_tail(&tmpq, inputq);
920 	spin_unlock_bh(&inputq->lock);
921 
922 }
923 
924 /**
925  * tipc_link_set_skb_retransmit_time - set the time at which retransmission of
926  *                                     the given skb should be next attempted
927  * @skb: skb to set a future retransmission time for
928  * @l: link the skb will be transmitted on
929  */
930 static void tipc_link_set_skb_retransmit_time(struct sk_buff *skb,
931 					      struct tipc_link *l)
932 {
933 	if (link_is_bc_sndlink(l))
934 		TIPC_SKB_CB(skb)->nxt_retr = TIPC_BC_RETR_LIM;
935 	else
936 		TIPC_SKB_CB(skb)->nxt_retr = TIPC_UC_RETR_TIME;
937 }
938 
939 void tipc_link_reset(struct tipc_link *l)
940 {
941 	struct sk_buff_head list;
942 	u32 imp;
943 
944 	__skb_queue_head_init(&list);
945 
946 	l->in_session = false;
947 	/* Force re-synch of peer session number before establishing */
948 	l->peer_session--;
949 	l->session++;
950 	l->mtu = l->advertised_mtu;
951 
952 	spin_lock_bh(&l->wakeupq.lock);
953 	skb_queue_splice_init(&l->wakeupq, &list);
954 	spin_unlock_bh(&l->wakeupq.lock);
955 
956 	spin_lock_bh(&l->inputq->lock);
957 	skb_queue_splice_init(&list, l->inputq);
958 	spin_unlock_bh(&l->inputq->lock);
959 
960 	__skb_queue_purge(&l->transmq);
961 	__skb_queue_purge(&l->deferdq);
962 	__skb_queue_purge(&l->backlogq);
963 	__skb_queue_purge(&l->failover_deferdq);
964 	for (imp = 0; imp <= TIPC_SYSTEM_IMPORTANCE; imp++) {
965 		l->backlog[imp].len = 0;
966 		l->backlog[imp].target_bskb = NULL;
967 	}
968 	kfree_skb(l->reasm_buf);
969 	kfree_skb(l->reasm_tnlmsg);
970 	kfree_skb(l->failover_reasm_skb);
971 	l->reasm_buf = NULL;
972 	l->reasm_tnlmsg = NULL;
973 	l->failover_reasm_skb = NULL;
974 	l->rcv_unacked = 0;
975 	l->snd_nxt = 1;
976 	l->rcv_nxt = 1;
977 	l->snd_nxt_state = 1;
978 	l->rcv_nxt_state = 1;
979 	l->acked = 0;
980 	l->last_gap = 0;
981 	kfree(l->last_ga);
982 	l->last_ga = NULL;
983 	l->silent_intv_cnt = 0;
984 	l->rst_cnt = 0;
985 	l->bc_peer_is_up = false;
986 	memset(&l->mon_state, 0, sizeof(l->mon_state));
987 	tipc_link_reset_stats(l);
988 }
989 
990 /**
991  * tipc_link_xmit(): enqueue buffer list according to queue situation
992  * @l: link to use
993  * @list: chain of buffers containing message
994  * @xmitq: returned list of packets to be sent by caller
995  *
996  * Consumes the buffer chain.
997  * Returns 0 if success, or errno: -ELINKCONG, -EMSGSIZE or -ENOBUFS
998  * Messages at TIPC_SYSTEM_IMPORTANCE are always accepted
999  */
1000 int tipc_link_xmit(struct tipc_link *l, struct sk_buff_head *list,
1001 		   struct sk_buff_head *xmitq)
1002 {
1003 	struct tipc_msg *hdr = buf_msg(skb_peek(list));
1004 	struct sk_buff_head *backlogq = &l->backlogq;
1005 	struct sk_buff_head *transmq = &l->transmq;
1006 	struct sk_buff *skb, *_skb;
1007 	u16 bc_ack = l->bc_rcvlink->rcv_nxt - 1;
1008 	u16 ack = l->rcv_nxt - 1;
1009 	u16 seqno = l->snd_nxt;
1010 	int pkt_cnt = skb_queue_len(list);
1011 	int imp = msg_importance(hdr);
1012 	unsigned int mss = tipc_link_mss(l);
1013 	unsigned int cwin = l->window;
1014 	unsigned int mtu = l->mtu;
1015 	bool new_bundle;
1016 	int rc = 0;
1017 
1018 	if (unlikely(msg_size(hdr) > mtu)) {
1019 		pr_warn("Too large msg, purging xmit list %d %d %d %d %d!\n",
1020 			skb_queue_len(list), msg_user(hdr),
1021 			msg_type(hdr), msg_size(hdr), mtu);
1022 		__skb_queue_purge(list);
1023 		return -EMSGSIZE;
1024 	}
1025 
1026 	/* Allow oversubscription of one data msg per source at congestion */
1027 	if (unlikely(l->backlog[imp].len >= l->backlog[imp].limit)) {
1028 		if (imp == TIPC_SYSTEM_IMPORTANCE) {
1029 			pr_warn("%s<%s>, link overflow", link_rst_msg, l->name);
1030 			return -ENOBUFS;
1031 		}
1032 		rc = link_schedule_user(l, hdr);
1033 	}
1034 
1035 	if (pkt_cnt > 1) {
1036 		l->stats.sent_fragmented++;
1037 		l->stats.sent_fragments += pkt_cnt;
1038 	}
1039 
1040 	/* Prepare each packet for sending, and add to relevant queue: */
1041 	while ((skb = __skb_dequeue(list))) {
1042 		if (likely(skb_queue_len(transmq) < cwin)) {
1043 			hdr = buf_msg(skb);
1044 			msg_set_seqno(hdr, seqno);
1045 			msg_set_ack(hdr, ack);
1046 			msg_set_bcast_ack(hdr, bc_ack);
1047 			_skb = skb_clone(skb, GFP_ATOMIC);
1048 			if (!_skb) {
1049 				kfree_skb(skb);
1050 				__skb_queue_purge(list);
1051 				return -ENOBUFS;
1052 			}
1053 			__skb_queue_tail(transmq, skb);
1054 			tipc_link_set_skb_retransmit_time(skb, l);
1055 			__skb_queue_tail(xmitq, _skb);
1056 			TIPC_SKB_CB(skb)->ackers = l->ackers;
1057 			l->rcv_unacked = 0;
1058 			l->stats.sent_pkts++;
1059 			seqno++;
1060 			continue;
1061 		}
1062 		if (tipc_msg_try_bundle(l->backlog[imp].target_bskb, &skb,
1063 					mss, l->addr, &new_bundle)) {
1064 			if (skb) {
1065 				/* Keep a ref. to the skb for next try */
1066 				l->backlog[imp].target_bskb = skb;
1067 				l->backlog[imp].len++;
1068 				__skb_queue_tail(backlogq, skb);
1069 			} else {
1070 				if (new_bundle) {
1071 					l->stats.sent_bundles++;
1072 					l->stats.sent_bundled++;
1073 				}
1074 				l->stats.sent_bundled++;
1075 			}
1076 			continue;
1077 		}
1078 		l->backlog[imp].target_bskb = NULL;
1079 		l->backlog[imp].len += (1 + skb_queue_len(list));
1080 		__skb_queue_tail(backlogq, skb);
1081 		skb_queue_splice_tail_init(list, backlogq);
1082 	}
1083 	l->snd_nxt = seqno;
1084 	return rc;
1085 }
1086 
1087 static void tipc_link_update_cwin(struct tipc_link *l, int released,
1088 				  bool retransmitted)
1089 {
1090 	int bklog_len = skb_queue_len(&l->backlogq);
1091 	struct sk_buff_head *txq = &l->transmq;
1092 	int txq_len = skb_queue_len(txq);
1093 	u16 cwin = l->window;
1094 
1095 	/* Enter fast recovery */
1096 	if (unlikely(retransmitted)) {
1097 		l->ssthresh = max_t(u16, l->window / 2, 300);
1098 		l->window = min_t(u16, l->ssthresh, l->window);
1099 		return;
1100 	}
1101 	/* Enter slow start */
1102 	if (unlikely(!released)) {
1103 		l->ssthresh = max_t(u16, l->window / 2, 300);
1104 		l->window = l->min_win;
1105 		return;
1106 	}
1107 	/* Don't increase window if no pressure on the transmit queue */
1108 	if (txq_len + bklog_len < cwin)
1109 		return;
1110 
1111 	/* Don't increase window if there are holes the transmit queue */
1112 	if (txq_len && l->snd_nxt - buf_seqno(skb_peek(txq)) != txq_len)
1113 		return;
1114 
1115 	l->cong_acks += released;
1116 
1117 	/* Slow start  */
1118 	if (cwin <= l->ssthresh) {
1119 		l->window = min_t(u16, cwin + released, l->max_win);
1120 		return;
1121 	}
1122 	/* Congestion avoidance */
1123 	if (l->cong_acks < cwin)
1124 		return;
1125 	l->window = min_t(u16, ++cwin, l->max_win);
1126 	l->cong_acks = 0;
1127 }
1128 
1129 static void tipc_link_advance_backlog(struct tipc_link *l,
1130 				      struct sk_buff_head *xmitq)
1131 {
1132 	u16 bc_ack = l->bc_rcvlink->rcv_nxt - 1;
1133 	struct sk_buff_head *txq = &l->transmq;
1134 	struct sk_buff *skb, *_skb;
1135 	u16 ack = l->rcv_nxt - 1;
1136 	u16 seqno = l->snd_nxt;
1137 	struct tipc_msg *hdr;
1138 	u16 cwin = l->window;
1139 	u32 imp;
1140 
1141 	while (skb_queue_len(txq) < cwin) {
1142 		skb = skb_peek(&l->backlogq);
1143 		if (!skb)
1144 			break;
1145 		_skb = skb_clone(skb, GFP_ATOMIC);
1146 		if (!_skb)
1147 			break;
1148 		__skb_dequeue(&l->backlogq);
1149 		hdr = buf_msg(skb);
1150 		imp = msg_importance(hdr);
1151 		l->backlog[imp].len--;
1152 		if (unlikely(skb == l->backlog[imp].target_bskb))
1153 			l->backlog[imp].target_bskb = NULL;
1154 		__skb_queue_tail(&l->transmq, skb);
1155 		tipc_link_set_skb_retransmit_time(skb, l);
1156 
1157 		__skb_queue_tail(xmitq, _skb);
1158 		TIPC_SKB_CB(skb)->ackers = l->ackers;
1159 		msg_set_seqno(hdr, seqno);
1160 		msg_set_ack(hdr, ack);
1161 		msg_set_bcast_ack(hdr, bc_ack);
1162 		l->rcv_unacked = 0;
1163 		l->stats.sent_pkts++;
1164 		seqno++;
1165 	}
1166 	l->snd_nxt = seqno;
1167 }
1168 
1169 /**
1170  * link_retransmit_failure() - Detect repeated retransmit failures
1171  * @l: tipc link sender
1172  * @r: tipc link receiver (= l in case of unicast)
1173  * @rc: returned code
1174  *
1175  * Return: true if the repeated retransmit failures happens, otherwise
1176  * false
1177  */
1178 static bool link_retransmit_failure(struct tipc_link *l, struct tipc_link *r,
1179 				    int *rc)
1180 {
1181 	struct sk_buff *skb = skb_peek(&l->transmq);
1182 	struct tipc_msg *hdr;
1183 
1184 	if (!skb)
1185 		return false;
1186 
1187 	if (!TIPC_SKB_CB(skb)->retr_cnt)
1188 		return false;
1189 
1190 	if (!time_after(jiffies, TIPC_SKB_CB(skb)->retr_stamp +
1191 			msecs_to_jiffies(r->tolerance * 10)))
1192 		return false;
1193 
1194 	hdr = buf_msg(skb);
1195 	if (link_is_bc_sndlink(l) && !less(r->acked, msg_seqno(hdr)))
1196 		return false;
1197 
1198 	pr_warn("Retransmission failure on link <%s>\n", l->name);
1199 	link_print(l, "State of link ");
1200 	pr_info("Failed msg: usr %u, typ %u, len %u, err %u\n",
1201 		msg_user(hdr), msg_type(hdr), msg_size(hdr), msg_errcode(hdr));
1202 	pr_info("sqno %u, prev: %x, dest: %x\n",
1203 		msg_seqno(hdr), msg_prevnode(hdr), msg_destnode(hdr));
1204 	pr_info("retr_stamp %d, retr_cnt %d\n",
1205 		jiffies_to_msecs(TIPC_SKB_CB(skb)->retr_stamp),
1206 		TIPC_SKB_CB(skb)->retr_cnt);
1207 
1208 	trace_tipc_list_dump(&l->transmq, true, "retrans failure!");
1209 	trace_tipc_link_dump(l, TIPC_DUMP_NONE, "retrans failure!");
1210 	trace_tipc_link_dump(r, TIPC_DUMP_NONE, "retrans failure!");
1211 
1212 	if (link_is_bc_sndlink(l)) {
1213 		r->state = LINK_RESET;
1214 		*rc |= TIPC_LINK_DOWN_EVT;
1215 	} else {
1216 		*rc |= tipc_link_fsm_evt(l, LINK_FAILURE_EVT);
1217 	}
1218 
1219 	return true;
1220 }
1221 
1222 /* tipc_data_input - deliver data and name distr msgs to upper layer
1223  *
1224  * Consumes buffer if message is of right type
1225  * Node lock must be held
1226  */
1227 static bool tipc_data_input(struct tipc_link *l, struct sk_buff *skb,
1228 			    struct sk_buff_head *inputq)
1229 {
1230 	struct sk_buff_head *mc_inputq = l->bc_rcvlink->inputq;
1231 	struct tipc_msg *hdr = buf_msg(skb);
1232 
1233 	switch (msg_user(hdr)) {
1234 	case TIPC_LOW_IMPORTANCE:
1235 	case TIPC_MEDIUM_IMPORTANCE:
1236 	case TIPC_HIGH_IMPORTANCE:
1237 	case TIPC_CRITICAL_IMPORTANCE:
1238 		if (unlikely(msg_in_group(hdr) || msg_mcast(hdr))) {
1239 			skb_queue_tail(mc_inputq, skb);
1240 			return true;
1241 		}
1242 		fallthrough;
1243 	case CONN_MANAGER:
1244 		skb_queue_tail(inputq, skb);
1245 		return true;
1246 	case GROUP_PROTOCOL:
1247 		skb_queue_tail(mc_inputq, skb);
1248 		return true;
1249 	case NAME_DISTRIBUTOR:
1250 		l->bc_rcvlink->state = LINK_ESTABLISHED;
1251 		skb_queue_tail(l->namedq, skb);
1252 		return true;
1253 	case MSG_BUNDLER:
1254 	case TUNNEL_PROTOCOL:
1255 	case MSG_FRAGMENTER:
1256 	case BCAST_PROTOCOL:
1257 		return false;
1258 	default:
1259 		pr_warn("Dropping received illegal msg type\n");
1260 		kfree_skb(skb);
1261 		return true;
1262 	};
1263 }
1264 
1265 /* tipc_link_input - process packet that has passed link protocol check
1266  *
1267  * Consumes buffer
1268  */
1269 static int tipc_link_input(struct tipc_link *l, struct sk_buff *skb,
1270 			   struct sk_buff_head *inputq,
1271 			   struct sk_buff **reasm_skb)
1272 {
1273 	struct tipc_msg *hdr = buf_msg(skb);
1274 	struct sk_buff *iskb;
1275 	struct sk_buff_head tmpq;
1276 	int usr = msg_user(hdr);
1277 	int pos = 0;
1278 
1279 	if (usr == MSG_BUNDLER) {
1280 		skb_queue_head_init(&tmpq);
1281 		l->stats.recv_bundles++;
1282 		l->stats.recv_bundled += msg_msgcnt(hdr);
1283 		while (tipc_msg_extract(skb, &iskb, &pos))
1284 			tipc_data_input(l, iskb, &tmpq);
1285 		tipc_skb_queue_splice_tail(&tmpq, inputq);
1286 		return 0;
1287 	} else if (usr == MSG_FRAGMENTER) {
1288 		l->stats.recv_fragments++;
1289 		if (tipc_buf_append(reasm_skb, &skb)) {
1290 			l->stats.recv_fragmented++;
1291 			tipc_data_input(l, skb, inputq);
1292 		} else if (!*reasm_skb && !link_is_bc_rcvlink(l)) {
1293 			pr_warn_ratelimited("Unable to build fragment list\n");
1294 			return tipc_link_fsm_evt(l, LINK_FAILURE_EVT);
1295 		}
1296 		return 0;
1297 	} else if (usr == BCAST_PROTOCOL) {
1298 		tipc_bcast_lock(l->net);
1299 		tipc_link_bc_init_rcv(l->bc_rcvlink, hdr);
1300 		tipc_bcast_unlock(l->net);
1301 	}
1302 
1303 	kfree_skb(skb);
1304 	return 0;
1305 }
1306 
1307 /* tipc_link_tnl_rcv() - receive TUNNEL_PROTOCOL message, drop or process the
1308  *			 inner message along with the ones in the old link's
1309  *			 deferdq
1310  * @l: tunnel link
1311  * @skb: TUNNEL_PROTOCOL message
1312  * @inputq: queue to put messages ready for delivery
1313  */
1314 static int tipc_link_tnl_rcv(struct tipc_link *l, struct sk_buff *skb,
1315 			     struct sk_buff_head *inputq)
1316 {
1317 	struct sk_buff **reasm_skb = &l->failover_reasm_skb;
1318 	struct sk_buff **reasm_tnlmsg = &l->reasm_tnlmsg;
1319 	struct sk_buff_head *fdefq = &l->failover_deferdq;
1320 	struct tipc_msg *hdr = buf_msg(skb);
1321 	struct sk_buff *iskb;
1322 	int ipos = 0;
1323 	int rc = 0;
1324 	u16 seqno;
1325 
1326 	if (msg_type(hdr) == SYNCH_MSG) {
1327 		kfree_skb(skb);
1328 		return 0;
1329 	}
1330 
1331 	/* Not a fragment? */
1332 	if (likely(!msg_nof_fragms(hdr))) {
1333 		if (unlikely(!tipc_msg_extract(skb, &iskb, &ipos))) {
1334 			pr_warn_ratelimited("Unable to extract msg, defq: %d\n",
1335 					    skb_queue_len(fdefq));
1336 			return 0;
1337 		}
1338 		kfree_skb(skb);
1339 	} else {
1340 		/* Set fragment type for buf_append */
1341 		if (msg_fragm_no(hdr) == 1)
1342 			msg_set_type(hdr, FIRST_FRAGMENT);
1343 		else if (msg_fragm_no(hdr) < msg_nof_fragms(hdr))
1344 			msg_set_type(hdr, FRAGMENT);
1345 		else
1346 			msg_set_type(hdr, LAST_FRAGMENT);
1347 
1348 		if (!tipc_buf_append(reasm_tnlmsg, &skb)) {
1349 			/* Successful but non-complete reassembly? */
1350 			if (*reasm_tnlmsg || link_is_bc_rcvlink(l))
1351 				return 0;
1352 			pr_warn_ratelimited("Unable to reassemble tunnel msg\n");
1353 			return tipc_link_fsm_evt(l, LINK_FAILURE_EVT);
1354 		}
1355 		iskb = skb;
1356 	}
1357 
1358 	do {
1359 		seqno = buf_seqno(iskb);
1360 		if (unlikely(less(seqno, l->drop_point))) {
1361 			kfree_skb(iskb);
1362 			continue;
1363 		}
1364 		if (unlikely(seqno != l->drop_point)) {
1365 			__tipc_skb_queue_sorted(fdefq, seqno, iskb);
1366 			continue;
1367 		}
1368 
1369 		l->drop_point++;
1370 		if (!tipc_data_input(l, iskb, inputq))
1371 			rc |= tipc_link_input(l, iskb, inputq, reasm_skb);
1372 		if (unlikely(rc))
1373 			break;
1374 	} while ((iskb = __tipc_skb_dequeue(fdefq, l->drop_point)));
1375 
1376 	return rc;
1377 }
1378 
1379 /**
1380  * tipc_get_gap_ack_blks - get Gap ACK blocks from PROTOCOL/STATE_MSG
1381  * @ga: returned pointer to the Gap ACK blocks if any
1382  * @l: the tipc link
1383  * @hdr: the PROTOCOL/STATE_MSG header
1384  * @uc: desired Gap ACK blocks type, i.e. unicast (= 1) or broadcast (= 0)
1385  *
1386  * Return: the total Gap ACK blocks size
1387  */
1388 u16 tipc_get_gap_ack_blks(struct tipc_gap_ack_blks **ga, struct tipc_link *l,
1389 			  struct tipc_msg *hdr, bool uc)
1390 {
1391 	struct tipc_gap_ack_blks *p;
1392 	u16 sz = 0;
1393 
1394 	/* Does peer support the Gap ACK blocks feature? */
1395 	if (l->peer_caps & TIPC_GAP_ACK_BLOCK) {
1396 		p = (struct tipc_gap_ack_blks *)msg_data(hdr);
1397 		sz = ntohs(p->len);
1398 		/* Sanity check */
1399 		if (sz == struct_size(p, gacks, p->ugack_cnt + p->bgack_cnt)) {
1400 			/* Good, check if the desired type exists */
1401 			if ((uc && p->ugack_cnt) || (!uc && p->bgack_cnt))
1402 				goto ok;
1403 		/* Backward compatible: peer might not support bc, but uc? */
1404 		} else if (uc && sz == struct_size(p, gacks, p->ugack_cnt)) {
1405 			if (p->ugack_cnt) {
1406 				p->bgack_cnt = 0;
1407 				goto ok;
1408 			}
1409 		}
1410 	}
1411 	/* Other cases: ignore! */
1412 	p = NULL;
1413 
1414 ok:
1415 	*ga = p;
1416 	return sz;
1417 }
1418 
1419 static u8 __tipc_build_gap_ack_blks(struct tipc_gap_ack_blks *ga,
1420 				    struct tipc_link *l, u8 start_index)
1421 {
1422 	struct tipc_gap_ack *gacks = &ga->gacks[start_index];
1423 	struct sk_buff *skb = skb_peek(&l->deferdq);
1424 	u16 expect, seqno = 0;
1425 	u8 n = 0;
1426 
1427 	if (!skb)
1428 		return 0;
1429 
1430 	expect = buf_seqno(skb);
1431 	skb_queue_walk(&l->deferdq, skb) {
1432 		seqno = buf_seqno(skb);
1433 		if (unlikely(more(seqno, expect))) {
1434 			gacks[n].ack = htons(expect - 1);
1435 			gacks[n].gap = htons(seqno - expect);
1436 			if (++n >= MAX_GAP_ACK_BLKS / 2) {
1437 				pr_info_ratelimited("Gacks on %s: %d, ql: %d!\n",
1438 						    l->name, n,
1439 						    skb_queue_len(&l->deferdq));
1440 				return n;
1441 			}
1442 		} else if (unlikely(less(seqno, expect))) {
1443 			pr_warn("Unexpected skb in deferdq!\n");
1444 			continue;
1445 		}
1446 		expect = seqno + 1;
1447 	}
1448 
1449 	/* last block */
1450 	gacks[n].ack = htons(seqno);
1451 	gacks[n].gap = 0;
1452 	n++;
1453 	return n;
1454 }
1455 
1456 /* tipc_build_gap_ack_blks - build Gap ACK blocks
1457  * @l: tipc unicast link
1458  * @hdr: the tipc message buffer to store the Gap ACK blocks after built
1459  *
1460  * The function builds Gap ACK blocks for both the unicast & broadcast receiver
1461  * links of a certain peer, the buffer after built has the network data format
1462  * as found at the struct tipc_gap_ack_blks definition.
1463  *
1464  * returns the actual allocated memory size
1465  */
1466 static u16 tipc_build_gap_ack_blks(struct tipc_link *l, struct tipc_msg *hdr)
1467 {
1468 	struct tipc_link *bcl = l->bc_rcvlink;
1469 	struct tipc_gap_ack_blks *ga;
1470 	u16 len;
1471 
1472 	ga = (struct tipc_gap_ack_blks *)msg_data(hdr);
1473 
1474 	/* Start with broadcast link first */
1475 	tipc_bcast_lock(bcl->net);
1476 	msg_set_bcast_ack(hdr, bcl->rcv_nxt - 1);
1477 	msg_set_bc_gap(hdr, link_bc_rcv_gap(bcl));
1478 	ga->bgack_cnt = __tipc_build_gap_ack_blks(ga, bcl, 0);
1479 	tipc_bcast_unlock(bcl->net);
1480 
1481 	/* Now for unicast link, but an explicit NACK only (???) */
1482 	ga->ugack_cnt = (msg_seq_gap(hdr)) ?
1483 			__tipc_build_gap_ack_blks(ga, l, ga->bgack_cnt) : 0;
1484 
1485 	/* Total len */
1486 	len = struct_size(ga, gacks, ga->bgack_cnt + ga->ugack_cnt);
1487 	ga->len = htons(len);
1488 	return len;
1489 }
1490 
1491 /* tipc_link_advance_transmq - advance TIPC link transmq queue by releasing
1492  *			       acked packets, also doing retransmissions if
1493  *			       gaps found
1494  * @l: tipc link with transmq queue to be advanced
1495  * @r: tipc link "receiver" i.e. in case of broadcast (= "l" if unicast)
1496  * @acked: seqno of last packet acked by peer without any gaps before
1497  * @gap: # of gap packets
1498  * @ga: buffer pointer to Gap ACK blocks from peer
1499  * @xmitq: queue for accumulating the retransmitted packets if any
1500  * @retransmitted: returned boolean value if a retransmission is really issued
1501  * @rc: returned code e.g. TIPC_LINK_DOWN_EVT if a repeated retransmit failures
1502  *      happens (- unlikely case)
1503  *
1504  * Return: the number of packets released from the link transmq
1505  */
1506 static int tipc_link_advance_transmq(struct tipc_link *l, struct tipc_link *r,
1507 				     u16 acked, u16 gap,
1508 				     struct tipc_gap_ack_blks *ga,
1509 				     struct sk_buff_head *xmitq,
1510 				     bool *retransmitted, int *rc)
1511 {
1512 	struct tipc_gap_ack_blks *last_ga = r->last_ga, *this_ga = NULL;
1513 	struct tipc_gap_ack *gacks = NULL;
1514 	struct sk_buff *skb, *_skb, *tmp;
1515 	struct tipc_msg *hdr;
1516 	u32 qlen = skb_queue_len(&l->transmq);
1517 	u16 nacked = acked, ngap = gap, gack_cnt = 0;
1518 	u16 bc_ack = l->bc_rcvlink->rcv_nxt - 1;
1519 	u16 ack = l->rcv_nxt - 1;
1520 	u16 seqno, n = 0;
1521 	u16 end = r->acked, start = end, offset = r->last_gap;
1522 	u16 si = (last_ga) ? last_ga->start_index : 0;
1523 	bool is_uc = !link_is_bc_sndlink(l);
1524 	bool bc_has_acked = false;
1525 
1526 	trace_tipc_link_retrans(r, acked + 1, acked + gap, &l->transmq);
1527 
1528 	/* Determine Gap ACK blocks if any for the particular link */
1529 	if (ga && is_uc) {
1530 		/* Get the Gap ACKs, uc part */
1531 		gack_cnt = ga->ugack_cnt;
1532 		gacks = &ga->gacks[ga->bgack_cnt];
1533 	} else if (ga) {
1534 		/* Copy the Gap ACKs, bc part, for later renewal if needed */
1535 		this_ga = kmemdup(ga, struct_size(ga, gacks, ga->bgack_cnt),
1536 				  GFP_ATOMIC);
1537 		if (likely(this_ga)) {
1538 			this_ga->start_index = 0;
1539 			/* Start with the bc Gap ACKs */
1540 			gack_cnt = this_ga->bgack_cnt;
1541 			gacks = &this_ga->gacks[0];
1542 		} else {
1543 			/* Hmm, we can get in trouble..., simply ignore it */
1544 			pr_warn_ratelimited("Ignoring bc Gap ACKs, no memory\n");
1545 		}
1546 	}
1547 
1548 	/* Advance the link transmq */
1549 	skb_queue_walk_safe(&l->transmq, skb, tmp) {
1550 		seqno = buf_seqno(skb);
1551 
1552 next_gap_ack:
1553 		if (less_eq(seqno, nacked)) {
1554 			if (is_uc)
1555 				goto release;
1556 			/* Skip packets peer has already acked */
1557 			if (!more(seqno, r->acked))
1558 				continue;
1559 			/* Get the next of last Gap ACK blocks */
1560 			while (more(seqno, end)) {
1561 				if (!last_ga || si >= last_ga->bgack_cnt)
1562 					break;
1563 				start = end + offset + 1;
1564 				end = ntohs(last_ga->gacks[si].ack);
1565 				offset = ntohs(last_ga->gacks[si].gap);
1566 				si++;
1567 				WARN_ONCE(more(start, end) ||
1568 					  (!offset &&
1569 					   si < last_ga->bgack_cnt) ||
1570 					  si > MAX_GAP_ACK_BLKS,
1571 					  "Corrupted Gap ACK: %d %d %d %d %d\n",
1572 					  start, end, offset, si,
1573 					  last_ga->bgack_cnt);
1574 			}
1575 			/* Check against the last Gap ACK block */
1576 			if (in_range(seqno, start, end))
1577 				continue;
1578 			/* Update/release the packet peer is acking */
1579 			bc_has_acked = true;
1580 			if (--TIPC_SKB_CB(skb)->ackers)
1581 				continue;
1582 release:
1583 			/* release skb */
1584 			__skb_unlink(skb, &l->transmq);
1585 			kfree_skb(skb);
1586 		} else if (less_eq(seqno, nacked + ngap)) {
1587 			/* First gap: check if repeated retrans failures? */
1588 			if (unlikely(seqno == acked + 1 &&
1589 				     link_retransmit_failure(l, r, rc))) {
1590 				/* Ignore this bc Gap ACKs if any */
1591 				kfree(this_ga);
1592 				this_ga = NULL;
1593 				break;
1594 			}
1595 			/* retransmit skb if unrestricted*/
1596 			if (time_before(jiffies, TIPC_SKB_CB(skb)->nxt_retr))
1597 				continue;
1598 			tipc_link_set_skb_retransmit_time(skb, l);
1599 			_skb = pskb_copy(skb, GFP_ATOMIC);
1600 			if (!_skb)
1601 				continue;
1602 			hdr = buf_msg(_skb);
1603 			msg_set_ack(hdr, ack);
1604 			msg_set_bcast_ack(hdr, bc_ack);
1605 			_skb->priority = TC_PRIO_CONTROL;
1606 			__skb_queue_tail(xmitq, _skb);
1607 			l->stats.retransmitted++;
1608 			if (!is_uc)
1609 				r->stats.retransmitted++;
1610 			*retransmitted = true;
1611 			/* Increase actual retrans counter & mark first time */
1612 			if (!TIPC_SKB_CB(skb)->retr_cnt++)
1613 				TIPC_SKB_CB(skb)->retr_stamp = jiffies;
1614 		} else {
1615 			/* retry with Gap ACK blocks if any */
1616 			if (n >= gack_cnt)
1617 				break;
1618 			nacked = ntohs(gacks[n].ack);
1619 			ngap = ntohs(gacks[n].gap);
1620 			n++;
1621 			goto next_gap_ack;
1622 		}
1623 	}
1624 
1625 	/* Renew last Gap ACK blocks for bc if needed */
1626 	if (bc_has_acked) {
1627 		if (this_ga) {
1628 			kfree(last_ga);
1629 			r->last_ga = this_ga;
1630 			r->last_gap = gap;
1631 		} else if (last_ga) {
1632 			if (less(acked, start)) {
1633 				si--;
1634 				offset = start - acked - 1;
1635 			} else if (less(acked, end)) {
1636 				acked = end;
1637 			}
1638 			if (si < last_ga->bgack_cnt) {
1639 				last_ga->start_index = si;
1640 				r->last_gap = offset;
1641 			} else {
1642 				kfree(last_ga);
1643 				r->last_ga = NULL;
1644 				r->last_gap = 0;
1645 			}
1646 		} else {
1647 			r->last_gap = 0;
1648 		}
1649 		r->acked = acked;
1650 	} else {
1651 		kfree(this_ga);
1652 	}
1653 
1654 	return qlen - skb_queue_len(&l->transmq);
1655 }
1656 
1657 /* tipc_link_build_state_msg: prepare link state message for transmission
1658  *
1659  * Note that sending of broadcast ack is coordinated among nodes, to reduce
1660  * risk of ack storms towards the sender
1661  */
1662 int tipc_link_build_state_msg(struct tipc_link *l, struct sk_buff_head *xmitq)
1663 {
1664 	if (!l)
1665 		return 0;
1666 
1667 	/* Broadcast ACK must be sent via a unicast link => defer to caller */
1668 	if (link_is_bc_rcvlink(l)) {
1669 		if (((l->rcv_nxt ^ tipc_own_addr(l->net)) & 0xf) != 0xf)
1670 			return 0;
1671 		l->rcv_unacked = 0;
1672 
1673 		/* Use snd_nxt to store peer's snd_nxt in broadcast rcv link */
1674 		l->snd_nxt = l->rcv_nxt;
1675 		return TIPC_LINK_SND_STATE;
1676 	}
1677 	/* Unicast ACK */
1678 	l->rcv_unacked = 0;
1679 	l->stats.sent_acks++;
1680 	tipc_link_build_proto_msg(l, STATE_MSG, 0, 0, 0, 0, 0, xmitq);
1681 	return 0;
1682 }
1683 
1684 /* tipc_link_build_reset_msg: prepare link RESET or ACTIVATE message
1685  */
1686 void tipc_link_build_reset_msg(struct tipc_link *l, struct sk_buff_head *xmitq)
1687 {
1688 	int mtyp = RESET_MSG;
1689 	struct sk_buff *skb;
1690 
1691 	if (l->state == LINK_ESTABLISHING)
1692 		mtyp = ACTIVATE_MSG;
1693 
1694 	tipc_link_build_proto_msg(l, mtyp, 0, 0, 0, 0, 0, xmitq);
1695 
1696 	/* Inform peer that this endpoint is going down if applicable */
1697 	skb = skb_peek_tail(xmitq);
1698 	if (skb && (l->state == LINK_RESET))
1699 		msg_set_peer_stopping(buf_msg(skb), 1);
1700 }
1701 
1702 /* tipc_link_build_nack_msg: prepare link nack message for transmission
1703  * Note that sending of broadcast NACK is coordinated among nodes, to
1704  * reduce the risk of NACK storms towards the sender
1705  */
1706 static int tipc_link_build_nack_msg(struct tipc_link *l,
1707 				    struct sk_buff_head *xmitq)
1708 {
1709 	u32 def_cnt = ++l->stats.deferred_recv;
1710 	struct sk_buff_head *dfq = &l->deferdq;
1711 	u32 defq_len = skb_queue_len(dfq);
1712 	int match1, match2;
1713 
1714 	if (link_is_bc_rcvlink(l)) {
1715 		match1 = def_cnt & 0xf;
1716 		match2 = tipc_own_addr(l->net) & 0xf;
1717 		if (match1 == match2)
1718 			return TIPC_LINK_SND_STATE;
1719 		return 0;
1720 	}
1721 
1722 	if (defq_len >= 3 && !((defq_len - 3) % 16)) {
1723 		u16 rcvgap = buf_seqno(skb_peek(dfq)) - l->rcv_nxt;
1724 
1725 		tipc_link_build_proto_msg(l, STATE_MSG, 0, 0,
1726 					  rcvgap, 0, 0, xmitq);
1727 	}
1728 	return 0;
1729 }
1730 
1731 /* tipc_link_rcv - process TIPC packets/messages arriving from off-node
1732  * @l: the link that should handle the message
1733  * @skb: TIPC packet
1734  * @xmitq: queue to place packets to be sent after this call
1735  */
1736 int tipc_link_rcv(struct tipc_link *l, struct sk_buff *skb,
1737 		  struct sk_buff_head *xmitq)
1738 {
1739 	struct sk_buff_head *defq = &l->deferdq;
1740 	struct tipc_msg *hdr = buf_msg(skb);
1741 	u16 seqno, rcv_nxt, win_lim;
1742 	int released = 0;
1743 	int rc = 0;
1744 
1745 	/* Verify and update link state */
1746 	if (unlikely(msg_user(hdr) == LINK_PROTOCOL))
1747 		return tipc_link_proto_rcv(l, skb, xmitq);
1748 
1749 	/* Don't send probe at next timeout expiration */
1750 	l->silent_intv_cnt = 0;
1751 
1752 	do {
1753 		hdr = buf_msg(skb);
1754 		seqno = msg_seqno(hdr);
1755 		rcv_nxt = l->rcv_nxt;
1756 		win_lim = rcv_nxt + TIPC_MAX_LINK_WIN;
1757 
1758 		if (unlikely(!link_is_up(l))) {
1759 			if (l->state == LINK_ESTABLISHING)
1760 				rc = TIPC_LINK_UP_EVT;
1761 			kfree_skb(skb);
1762 			break;
1763 		}
1764 
1765 		/* Drop if outside receive window */
1766 		if (unlikely(less(seqno, rcv_nxt) || more(seqno, win_lim))) {
1767 			l->stats.duplicates++;
1768 			kfree_skb(skb);
1769 			break;
1770 		}
1771 		released += tipc_link_advance_transmq(l, l, msg_ack(hdr), 0,
1772 						      NULL, NULL, NULL, NULL);
1773 
1774 		/* Defer delivery if sequence gap */
1775 		if (unlikely(seqno != rcv_nxt)) {
1776 			if (!__tipc_skb_queue_sorted(defq, seqno, skb))
1777 				l->stats.duplicates++;
1778 			rc |= tipc_link_build_nack_msg(l, xmitq);
1779 			break;
1780 		}
1781 
1782 		/* Deliver packet */
1783 		l->rcv_nxt++;
1784 		l->stats.recv_pkts++;
1785 
1786 		if (unlikely(msg_user(hdr) == TUNNEL_PROTOCOL))
1787 			rc |= tipc_link_tnl_rcv(l, skb, l->inputq);
1788 		else if (!tipc_data_input(l, skb, l->inputq))
1789 			rc |= tipc_link_input(l, skb, l->inputq, &l->reasm_buf);
1790 		if (unlikely(++l->rcv_unacked >= TIPC_MIN_LINK_WIN))
1791 			rc |= tipc_link_build_state_msg(l, xmitq);
1792 		if (unlikely(rc & ~TIPC_LINK_SND_STATE))
1793 			break;
1794 	} while ((skb = __tipc_skb_dequeue(defq, l->rcv_nxt)));
1795 
1796 	/* Forward queues and wake up waiting users */
1797 	if (released) {
1798 		tipc_link_update_cwin(l, released, 0);
1799 		tipc_link_advance_backlog(l, xmitq);
1800 		if (unlikely(!skb_queue_empty(&l->wakeupq)))
1801 			link_prepare_wakeup(l);
1802 	}
1803 	return rc;
1804 }
1805 
1806 static void tipc_link_build_proto_msg(struct tipc_link *l, int mtyp, bool probe,
1807 				      bool probe_reply, u16 rcvgap,
1808 				      int tolerance, int priority,
1809 				      struct sk_buff_head *xmitq)
1810 {
1811 	struct tipc_mon_state *mstate = &l->mon_state;
1812 	struct sk_buff_head *dfq = &l->deferdq;
1813 	struct tipc_link *bcl = l->bc_rcvlink;
1814 	struct tipc_msg *hdr;
1815 	struct sk_buff *skb;
1816 	bool node_up = link_is_up(bcl);
1817 	u16 glen = 0, bc_rcvgap = 0;
1818 	int dlen = 0;
1819 	void *data;
1820 
1821 	/* Don't send protocol message during reset or link failover */
1822 	if (tipc_link_is_blocked(l))
1823 		return;
1824 
1825 	if (!tipc_link_is_up(l) && (mtyp == STATE_MSG))
1826 		return;
1827 
1828 	if ((probe || probe_reply) && !skb_queue_empty(dfq))
1829 		rcvgap = buf_seqno(skb_peek(dfq)) - l->rcv_nxt;
1830 
1831 	skb = tipc_msg_create(LINK_PROTOCOL, mtyp, INT_H_SIZE,
1832 			      tipc_max_domain_size + MAX_GAP_ACK_BLKS_SZ,
1833 			      l->addr, tipc_own_addr(l->net), 0, 0, 0);
1834 	if (!skb)
1835 		return;
1836 
1837 	hdr = buf_msg(skb);
1838 	data = msg_data(hdr);
1839 	msg_set_session(hdr, l->session);
1840 	msg_set_bearer_id(hdr, l->bearer_id);
1841 	msg_set_net_plane(hdr, l->net_plane);
1842 	msg_set_next_sent(hdr, l->snd_nxt);
1843 	msg_set_ack(hdr, l->rcv_nxt - 1);
1844 	msg_set_bcast_ack(hdr, bcl->rcv_nxt - 1);
1845 	msg_set_bc_ack_invalid(hdr, !node_up);
1846 	msg_set_last_bcast(hdr, l->bc_sndlink->snd_nxt - 1);
1847 	msg_set_link_tolerance(hdr, tolerance);
1848 	msg_set_linkprio(hdr, priority);
1849 	msg_set_redundant_link(hdr, node_up);
1850 	msg_set_seq_gap(hdr, 0);
1851 	msg_set_seqno(hdr, l->snd_nxt + U16_MAX / 2);
1852 
1853 	if (mtyp == STATE_MSG) {
1854 		if (l->peer_caps & TIPC_LINK_PROTO_SEQNO)
1855 			msg_set_seqno(hdr, l->snd_nxt_state++);
1856 		msg_set_seq_gap(hdr, rcvgap);
1857 		bc_rcvgap = link_bc_rcv_gap(bcl);
1858 		msg_set_bc_gap(hdr, bc_rcvgap);
1859 		msg_set_probe(hdr, probe);
1860 		msg_set_is_keepalive(hdr, probe || probe_reply);
1861 		if (l->peer_caps & TIPC_GAP_ACK_BLOCK)
1862 			glen = tipc_build_gap_ack_blks(l, hdr);
1863 		tipc_mon_prep(l->net, data + glen, &dlen, mstate, l->bearer_id);
1864 		msg_set_size(hdr, INT_H_SIZE + glen + dlen);
1865 		skb_trim(skb, INT_H_SIZE + glen + dlen);
1866 		l->stats.sent_states++;
1867 		l->rcv_unacked = 0;
1868 	} else {
1869 		/* RESET_MSG or ACTIVATE_MSG */
1870 		if (mtyp == ACTIVATE_MSG) {
1871 			msg_set_dest_session_valid(hdr, 1);
1872 			msg_set_dest_session(hdr, l->peer_session);
1873 		}
1874 		msg_set_max_pkt(hdr, l->advertised_mtu);
1875 		strcpy(data, l->if_name);
1876 		msg_set_size(hdr, INT_H_SIZE + TIPC_MAX_IF_NAME);
1877 		skb_trim(skb, INT_H_SIZE + TIPC_MAX_IF_NAME);
1878 	}
1879 	if (probe)
1880 		l->stats.sent_probes++;
1881 	if (rcvgap)
1882 		l->stats.sent_nacks++;
1883 	if (bc_rcvgap)
1884 		bcl->stats.sent_nacks++;
1885 	skb->priority = TC_PRIO_CONTROL;
1886 	__skb_queue_tail(xmitq, skb);
1887 	trace_tipc_proto_build(skb, false, l->name);
1888 }
1889 
1890 void tipc_link_create_dummy_tnl_msg(struct tipc_link *l,
1891 				    struct sk_buff_head *xmitq)
1892 {
1893 	u32 onode = tipc_own_addr(l->net);
1894 	struct tipc_msg *hdr, *ihdr;
1895 	struct sk_buff_head tnlq;
1896 	struct sk_buff *skb;
1897 	u32 dnode = l->addr;
1898 
1899 	__skb_queue_head_init(&tnlq);
1900 	skb = tipc_msg_create(TUNNEL_PROTOCOL, FAILOVER_MSG,
1901 			      INT_H_SIZE, BASIC_H_SIZE,
1902 			      dnode, onode, 0, 0, 0);
1903 	if (!skb) {
1904 		pr_warn("%sunable to create tunnel packet\n", link_co_err);
1905 		return;
1906 	}
1907 
1908 	hdr = buf_msg(skb);
1909 	msg_set_msgcnt(hdr, 1);
1910 	msg_set_bearer_id(hdr, l->peer_bearer_id);
1911 
1912 	ihdr = (struct tipc_msg *)msg_data(hdr);
1913 	tipc_msg_init(onode, ihdr, TIPC_LOW_IMPORTANCE, TIPC_DIRECT_MSG,
1914 		      BASIC_H_SIZE, dnode);
1915 	msg_set_errcode(ihdr, TIPC_ERR_NO_PORT);
1916 	__skb_queue_tail(&tnlq, skb);
1917 	tipc_link_xmit(l, &tnlq, xmitq);
1918 }
1919 
1920 /* tipc_link_tnl_prepare(): prepare and return a list of tunnel packets
1921  * with contents of the link's transmit and backlog queues.
1922  */
1923 void tipc_link_tnl_prepare(struct tipc_link *l, struct tipc_link *tnl,
1924 			   int mtyp, struct sk_buff_head *xmitq)
1925 {
1926 	struct sk_buff_head *fdefq = &tnl->failover_deferdq;
1927 	struct sk_buff *skb, *tnlskb;
1928 	struct tipc_msg *hdr, tnlhdr;
1929 	struct sk_buff_head *queue = &l->transmq;
1930 	struct sk_buff_head tmpxq, tnlq, frags;
1931 	u16 pktlen, pktcnt, seqno = l->snd_nxt;
1932 	bool pktcnt_need_update = false;
1933 	u16 syncpt;
1934 	int rc;
1935 
1936 	if (!tnl)
1937 		return;
1938 
1939 	__skb_queue_head_init(&tnlq);
1940 	/* Link Synching:
1941 	 * From now on, send only one single ("dummy") SYNCH message
1942 	 * to peer. The SYNCH message does not contain any data, just
1943 	 * a header conveying the synch point to the peer.
1944 	 */
1945 	if (mtyp == SYNCH_MSG && (tnl->peer_caps & TIPC_TUNNEL_ENHANCED)) {
1946 		tnlskb = tipc_msg_create(TUNNEL_PROTOCOL, SYNCH_MSG,
1947 					 INT_H_SIZE, 0, l->addr,
1948 					 tipc_own_addr(l->net),
1949 					 0, 0, 0);
1950 		if (!tnlskb) {
1951 			pr_warn("%sunable to create dummy SYNCH_MSG\n",
1952 				link_co_err);
1953 			return;
1954 		}
1955 
1956 		hdr = buf_msg(tnlskb);
1957 		syncpt = l->snd_nxt + skb_queue_len(&l->backlogq) - 1;
1958 		msg_set_syncpt(hdr, syncpt);
1959 		msg_set_bearer_id(hdr, l->peer_bearer_id);
1960 		__skb_queue_tail(&tnlq, tnlskb);
1961 		tipc_link_xmit(tnl, &tnlq, xmitq);
1962 		return;
1963 	}
1964 
1965 	__skb_queue_head_init(&tmpxq);
1966 	__skb_queue_head_init(&frags);
1967 	/* At least one packet required for safe algorithm => add dummy */
1968 	skb = tipc_msg_create(TIPC_LOW_IMPORTANCE, TIPC_DIRECT_MSG,
1969 			      BASIC_H_SIZE, 0, l->addr, tipc_own_addr(l->net),
1970 			      0, 0, TIPC_ERR_NO_PORT);
1971 	if (!skb) {
1972 		pr_warn("%sunable to create tunnel packet\n", link_co_err);
1973 		return;
1974 	}
1975 	__skb_queue_tail(&tnlq, skb);
1976 	tipc_link_xmit(l, &tnlq, &tmpxq);
1977 	__skb_queue_purge(&tmpxq);
1978 
1979 	/* Initialize reusable tunnel packet header */
1980 	tipc_msg_init(tipc_own_addr(l->net), &tnlhdr, TUNNEL_PROTOCOL,
1981 		      mtyp, INT_H_SIZE, l->addr);
1982 	if (mtyp == SYNCH_MSG)
1983 		pktcnt = l->snd_nxt - buf_seqno(skb_peek(&l->transmq));
1984 	else
1985 		pktcnt = skb_queue_len(&l->transmq);
1986 	pktcnt += skb_queue_len(&l->backlogq);
1987 	msg_set_msgcnt(&tnlhdr, pktcnt);
1988 	msg_set_bearer_id(&tnlhdr, l->peer_bearer_id);
1989 tnl:
1990 	/* Wrap each packet into a tunnel packet */
1991 	skb_queue_walk(queue, skb) {
1992 		hdr = buf_msg(skb);
1993 		if (queue == &l->backlogq)
1994 			msg_set_seqno(hdr, seqno++);
1995 		pktlen = msg_size(hdr);
1996 
1997 		/* Tunnel link MTU is not large enough? This could be
1998 		 * due to:
1999 		 * 1) Link MTU has just changed or set differently;
2000 		 * 2) Or FAILOVER on the top of a SYNCH message
2001 		 *
2002 		 * The 2nd case should not happen if peer supports
2003 		 * TIPC_TUNNEL_ENHANCED
2004 		 */
2005 		if (pktlen > tnl->mtu - INT_H_SIZE) {
2006 			if (mtyp == FAILOVER_MSG &&
2007 			    (tnl->peer_caps & TIPC_TUNNEL_ENHANCED)) {
2008 				rc = tipc_msg_fragment(skb, &tnlhdr, tnl->mtu,
2009 						       &frags);
2010 				if (rc) {
2011 					pr_warn("%sunable to frag msg: rc %d\n",
2012 						link_co_err, rc);
2013 					return;
2014 				}
2015 				pktcnt += skb_queue_len(&frags) - 1;
2016 				pktcnt_need_update = true;
2017 				skb_queue_splice_tail_init(&frags, &tnlq);
2018 				continue;
2019 			}
2020 			/* Unluckily, peer doesn't have TIPC_TUNNEL_ENHANCED
2021 			 * => Just warn it and return!
2022 			 */
2023 			pr_warn_ratelimited("%stoo large msg <%d, %d>: %d!\n",
2024 					    link_co_err, msg_user(hdr),
2025 					    msg_type(hdr), msg_size(hdr));
2026 			return;
2027 		}
2028 
2029 		msg_set_size(&tnlhdr, pktlen + INT_H_SIZE);
2030 		tnlskb = tipc_buf_acquire(pktlen + INT_H_SIZE, GFP_ATOMIC);
2031 		if (!tnlskb) {
2032 			pr_warn("%sunable to send packet\n", link_co_err);
2033 			return;
2034 		}
2035 		skb_copy_to_linear_data(tnlskb, &tnlhdr, INT_H_SIZE);
2036 		skb_copy_to_linear_data_offset(tnlskb, INT_H_SIZE, hdr, pktlen);
2037 		__skb_queue_tail(&tnlq, tnlskb);
2038 	}
2039 	if (queue != &l->backlogq) {
2040 		queue = &l->backlogq;
2041 		goto tnl;
2042 	}
2043 
2044 	if (pktcnt_need_update)
2045 		skb_queue_walk(&tnlq, skb) {
2046 			hdr = buf_msg(skb);
2047 			msg_set_msgcnt(hdr, pktcnt);
2048 		}
2049 
2050 	tipc_link_xmit(tnl, &tnlq, xmitq);
2051 
2052 	if (mtyp == FAILOVER_MSG) {
2053 		tnl->drop_point = l->rcv_nxt;
2054 		tnl->failover_reasm_skb = l->reasm_buf;
2055 		l->reasm_buf = NULL;
2056 
2057 		/* Failover the link's deferdq */
2058 		if (unlikely(!skb_queue_empty(fdefq))) {
2059 			pr_warn("Link failover deferdq not empty: %d!\n",
2060 				skb_queue_len(fdefq));
2061 			__skb_queue_purge(fdefq);
2062 		}
2063 		skb_queue_splice_init(&l->deferdq, fdefq);
2064 	}
2065 }
2066 
2067 /**
2068  * tipc_link_failover_prepare() - prepare tnl for link failover
2069  *
2070  * This is a special version of the precursor - tipc_link_tnl_prepare(),
2071  * see the tipc_node_link_failover() for details
2072  *
2073  * @l: failover link
2074  * @tnl: tunnel link
2075  * @xmitq: queue for messages to be xmited
2076  */
2077 void tipc_link_failover_prepare(struct tipc_link *l, struct tipc_link *tnl,
2078 				struct sk_buff_head *xmitq)
2079 {
2080 	struct sk_buff_head *fdefq = &tnl->failover_deferdq;
2081 
2082 	tipc_link_create_dummy_tnl_msg(tnl, xmitq);
2083 
2084 	/* This failover link endpoint was never established before,
2085 	 * so it has not received anything from peer.
2086 	 * Otherwise, it must be a normal failover situation or the
2087 	 * node has entered SELF_DOWN_PEER_LEAVING and both peer nodes
2088 	 * would have to start over from scratch instead.
2089 	 */
2090 	tnl->drop_point = 1;
2091 	tnl->failover_reasm_skb = NULL;
2092 
2093 	/* Initiate the link's failover deferdq */
2094 	if (unlikely(!skb_queue_empty(fdefq))) {
2095 		pr_warn("Link failover deferdq not empty: %d!\n",
2096 			skb_queue_len(fdefq));
2097 		__skb_queue_purge(fdefq);
2098 	}
2099 }
2100 
2101 /* tipc_link_validate_msg(): validate message against current link state
2102  * Returns true if message should be accepted, otherwise false
2103  */
2104 bool tipc_link_validate_msg(struct tipc_link *l, struct tipc_msg *hdr)
2105 {
2106 	u16 curr_session = l->peer_session;
2107 	u16 session = msg_session(hdr);
2108 	int mtyp = msg_type(hdr);
2109 
2110 	if (msg_user(hdr) != LINK_PROTOCOL)
2111 		return true;
2112 
2113 	switch (mtyp) {
2114 	case RESET_MSG:
2115 		if (!l->in_session)
2116 			return true;
2117 		/* Accept only RESET with new session number */
2118 		return more(session, curr_session);
2119 	case ACTIVATE_MSG:
2120 		if (!l->in_session)
2121 			return true;
2122 		/* Accept only ACTIVATE with new or current session number */
2123 		return !less(session, curr_session);
2124 	case STATE_MSG:
2125 		/* Accept only STATE with current session number */
2126 		if (!l->in_session)
2127 			return false;
2128 		if (session != curr_session)
2129 			return false;
2130 		/* Extra sanity check */
2131 		if (!link_is_up(l) && msg_ack(hdr))
2132 			return false;
2133 		if (!(l->peer_caps & TIPC_LINK_PROTO_SEQNO))
2134 			return true;
2135 		/* Accept only STATE with new sequence number */
2136 		return !less(msg_seqno(hdr), l->rcv_nxt_state);
2137 	default:
2138 		return false;
2139 	}
2140 }
2141 
2142 /* tipc_link_proto_rcv(): receive link level protocol message :
2143  * Note that network plane id propagates through the network, and may
2144  * change at any time. The node with lowest numerical id determines
2145  * network plane
2146  */
2147 static int tipc_link_proto_rcv(struct tipc_link *l, struct sk_buff *skb,
2148 			       struct sk_buff_head *xmitq)
2149 {
2150 	struct tipc_msg *hdr = buf_msg(skb);
2151 	struct tipc_gap_ack_blks *ga = NULL;
2152 	bool reply = msg_probe(hdr), retransmitted = false;
2153 	u16 dlen = msg_data_sz(hdr), glen = 0;
2154 	u16 peers_snd_nxt =  msg_next_sent(hdr);
2155 	u16 peers_tol = msg_link_tolerance(hdr);
2156 	u16 peers_prio = msg_linkprio(hdr);
2157 	u16 gap = msg_seq_gap(hdr);
2158 	u16 ack = msg_ack(hdr);
2159 	u16 rcv_nxt = l->rcv_nxt;
2160 	u16 rcvgap = 0;
2161 	int mtyp = msg_type(hdr);
2162 	int rc = 0, released;
2163 	char *if_name;
2164 	void *data;
2165 
2166 	trace_tipc_proto_rcv(skb, false, l->name);
2167 	if (tipc_link_is_blocked(l) || !xmitq)
2168 		goto exit;
2169 
2170 	if (tipc_own_addr(l->net) > msg_prevnode(hdr))
2171 		l->net_plane = msg_net_plane(hdr);
2172 
2173 	skb_linearize(skb);
2174 	hdr = buf_msg(skb);
2175 	data = msg_data(hdr);
2176 
2177 	if (!tipc_link_validate_msg(l, hdr)) {
2178 		trace_tipc_skb_dump(skb, false, "PROTO invalid (1)!");
2179 		trace_tipc_link_dump(l, TIPC_DUMP_NONE, "PROTO invalid (1)!");
2180 		goto exit;
2181 	}
2182 
2183 	switch (mtyp) {
2184 	case RESET_MSG:
2185 	case ACTIVATE_MSG:
2186 		/* Complete own link name with peer's interface name */
2187 		if_name =  strrchr(l->name, ':') + 1;
2188 		if (sizeof(l->name) - (if_name - l->name) <= TIPC_MAX_IF_NAME)
2189 			break;
2190 		if (msg_data_sz(hdr) < TIPC_MAX_IF_NAME)
2191 			break;
2192 		strncpy(if_name, data, TIPC_MAX_IF_NAME);
2193 
2194 		/* Update own tolerance if peer indicates a non-zero value */
2195 		if (in_range(peers_tol, TIPC_MIN_LINK_TOL, TIPC_MAX_LINK_TOL)) {
2196 			l->tolerance = peers_tol;
2197 			l->bc_rcvlink->tolerance = peers_tol;
2198 		}
2199 		/* Update own priority if peer's priority is higher */
2200 		if (in_range(peers_prio, l->priority + 1, TIPC_MAX_LINK_PRI))
2201 			l->priority = peers_prio;
2202 
2203 		/* If peer is going down we want full re-establish cycle */
2204 		if (msg_peer_stopping(hdr)) {
2205 			rc = tipc_link_fsm_evt(l, LINK_FAILURE_EVT);
2206 			break;
2207 		}
2208 
2209 		/* If this endpoint was re-created while peer was ESTABLISHING
2210 		 * it doesn't know current session number. Force re-synch.
2211 		 */
2212 		if (mtyp == ACTIVATE_MSG && msg_dest_session_valid(hdr) &&
2213 		    l->session != msg_dest_session(hdr)) {
2214 			if (less(l->session, msg_dest_session(hdr)))
2215 				l->session = msg_dest_session(hdr) + 1;
2216 			break;
2217 		}
2218 
2219 		/* ACTIVATE_MSG serves as PEER_RESET if link is already down */
2220 		if (mtyp == RESET_MSG || !link_is_up(l))
2221 			rc = tipc_link_fsm_evt(l, LINK_PEER_RESET_EVT);
2222 
2223 		/* ACTIVATE_MSG takes up link if it was already locally reset */
2224 		if (mtyp == ACTIVATE_MSG && l->state == LINK_ESTABLISHING)
2225 			rc = TIPC_LINK_UP_EVT;
2226 
2227 		l->peer_session = msg_session(hdr);
2228 		l->in_session = true;
2229 		l->peer_bearer_id = msg_bearer_id(hdr);
2230 		if (l->mtu > msg_max_pkt(hdr))
2231 			l->mtu = msg_max_pkt(hdr);
2232 		break;
2233 
2234 	case STATE_MSG:
2235 		l->rcv_nxt_state = msg_seqno(hdr) + 1;
2236 
2237 		/* Update own tolerance if peer indicates a non-zero value */
2238 		if (in_range(peers_tol, TIPC_MIN_LINK_TOL, TIPC_MAX_LINK_TOL)) {
2239 			l->tolerance = peers_tol;
2240 			l->bc_rcvlink->tolerance = peers_tol;
2241 		}
2242 		/* Update own prio if peer indicates a different value */
2243 		if ((peers_prio != l->priority) &&
2244 		    in_range(peers_prio, 1, TIPC_MAX_LINK_PRI)) {
2245 			l->priority = peers_prio;
2246 			rc = tipc_link_fsm_evt(l, LINK_FAILURE_EVT);
2247 		}
2248 
2249 		l->silent_intv_cnt = 0;
2250 		l->stats.recv_states++;
2251 		if (msg_probe(hdr))
2252 			l->stats.recv_probes++;
2253 
2254 		if (!link_is_up(l)) {
2255 			if (l->state == LINK_ESTABLISHING)
2256 				rc = TIPC_LINK_UP_EVT;
2257 			break;
2258 		}
2259 
2260 		/* Receive Gap ACK blocks from peer if any */
2261 		glen = tipc_get_gap_ack_blks(&ga, l, hdr, true);
2262 
2263 		tipc_mon_rcv(l->net, data + glen, dlen - glen, l->addr,
2264 			     &l->mon_state, l->bearer_id);
2265 
2266 		/* Send NACK if peer has sent pkts we haven't received yet */
2267 		if ((reply || msg_is_keepalive(hdr)) &&
2268 		    more(peers_snd_nxt, rcv_nxt) &&
2269 		    !tipc_link_is_synching(l) &&
2270 		    skb_queue_empty(&l->deferdq))
2271 			rcvgap = peers_snd_nxt - l->rcv_nxt;
2272 		if (rcvgap || reply)
2273 			tipc_link_build_proto_msg(l, STATE_MSG, 0, reply,
2274 						  rcvgap, 0, 0, xmitq);
2275 
2276 		released = tipc_link_advance_transmq(l, l, ack, gap, ga, xmitq,
2277 						     &retransmitted, &rc);
2278 		if (gap)
2279 			l->stats.recv_nacks++;
2280 		if (released || retransmitted)
2281 			tipc_link_update_cwin(l, released, retransmitted);
2282 		if (released)
2283 			tipc_link_advance_backlog(l, xmitq);
2284 		if (unlikely(!skb_queue_empty(&l->wakeupq)))
2285 			link_prepare_wakeup(l);
2286 	}
2287 exit:
2288 	kfree_skb(skb);
2289 	return rc;
2290 }
2291 
2292 /* tipc_link_build_bc_proto_msg() - create broadcast protocol message
2293  */
2294 static bool tipc_link_build_bc_proto_msg(struct tipc_link *l, bool bcast,
2295 					 u16 peers_snd_nxt,
2296 					 struct sk_buff_head *xmitq)
2297 {
2298 	struct sk_buff *skb;
2299 	struct tipc_msg *hdr;
2300 	struct sk_buff *dfrd_skb = skb_peek(&l->deferdq);
2301 	u16 ack = l->rcv_nxt - 1;
2302 	u16 gap_to = peers_snd_nxt - 1;
2303 
2304 	skb = tipc_msg_create(BCAST_PROTOCOL, STATE_MSG, INT_H_SIZE,
2305 			      0, l->addr, tipc_own_addr(l->net), 0, 0, 0);
2306 	if (!skb)
2307 		return false;
2308 	hdr = buf_msg(skb);
2309 	msg_set_last_bcast(hdr, l->bc_sndlink->snd_nxt - 1);
2310 	msg_set_bcast_ack(hdr, ack);
2311 	msg_set_bcgap_after(hdr, ack);
2312 	if (dfrd_skb)
2313 		gap_to = buf_seqno(dfrd_skb) - 1;
2314 	msg_set_bcgap_to(hdr, gap_to);
2315 	msg_set_non_seq(hdr, bcast);
2316 	__skb_queue_tail(xmitq, skb);
2317 	return true;
2318 }
2319 
2320 /* tipc_link_build_bc_init_msg() - synchronize broadcast link endpoints.
2321  *
2322  * Give a newly added peer node the sequence number where it should
2323  * start receiving and acking broadcast packets.
2324  */
2325 static void tipc_link_build_bc_init_msg(struct tipc_link *l,
2326 					struct sk_buff_head *xmitq)
2327 {
2328 	struct sk_buff_head list;
2329 
2330 	__skb_queue_head_init(&list);
2331 	if (!tipc_link_build_bc_proto_msg(l->bc_rcvlink, false, 0, &list))
2332 		return;
2333 	msg_set_bc_ack_invalid(buf_msg(skb_peek(&list)), true);
2334 	tipc_link_xmit(l, &list, xmitq);
2335 }
2336 
2337 /* tipc_link_bc_init_rcv - receive initial broadcast synch data from peer
2338  */
2339 void tipc_link_bc_init_rcv(struct tipc_link *l, struct tipc_msg *hdr)
2340 {
2341 	int mtyp = msg_type(hdr);
2342 	u16 peers_snd_nxt = msg_bc_snd_nxt(hdr);
2343 
2344 	if (link_is_up(l))
2345 		return;
2346 
2347 	if (msg_user(hdr) == BCAST_PROTOCOL) {
2348 		l->rcv_nxt = peers_snd_nxt;
2349 		l->state = LINK_ESTABLISHED;
2350 		return;
2351 	}
2352 
2353 	if (l->peer_caps & TIPC_BCAST_SYNCH)
2354 		return;
2355 
2356 	if (msg_peer_node_is_up(hdr))
2357 		return;
2358 
2359 	/* Compatibility: accept older, less safe initial synch data */
2360 	if ((mtyp == RESET_MSG) || (mtyp == ACTIVATE_MSG))
2361 		l->rcv_nxt = peers_snd_nxt;
2362 }
2363 
2364 /* tipc_link_bc_sync_rcv - update rcv link according to peer's send state
2365  */
2366 int tipc_link_bc_sync_rcv(struct tipc_link *l, struct tipc_msg *hdr,
2367 			  struct sk_buff_head *xmitq)
2368 {
2369 	u16 peers_snd_nxt = msg_bc_snd_nxt(hdr);
2370 	int rc = 0;
2371 
2372 	if (!link_is_up(l))
2373 		return rc;
2374 
2375 	if (!msg_peer_node_is_up(hdr))
2376 		return rc;
2377 
2378 	/* Open when peer ackowledges our bcast init msg (pkt #1) */
2379 	if (msg_ack(hdr))
2380 		l->bc_peer_is_up = true;
2381 
2382 	if (!l->bc_peer_is_up)
2383 		return rc;
2384 
2385 	/* Ignore if peers_snd_nxt goes beyond receive window */
2386 	if (more(peers_snd_nxt, l->rcv_nxt + l->window))
2387 		return rc;
2388 
2389 	l->snd_nxt = peers_snd_nxt;
2390 	if (link_bc_rcv_gap(l))
2391 		rc |= TIPC_LINK_SND_STATE;
2392 
2393 	/* Return now if sender supports nack via STATE messages */
2394 	if (l->peer_caps & TIPC_BCAST_STATE_NACK)
2395 		return rc;
2396 
2397 	/* Otherwise, be backwards compatible */
2398 
2399 	if (!more(peers_snd_nxt, l->rcv_nxt)) {
2400 		l->nack_state = BC_NACK_SND_CONDITIONAL;
2401 		return 0;
2402 	}
2403 
2404 	/* Don't NACK if one was recently sent or peeked */
2405 	if (l->nack_state == BC_NACK_SND_SUPPRESS) {
2406 		l->nack_state = BC_NACK_SND_UNCONDITIONAL;
2407 		return 0;
2408 	}
2409 
2410 	/* Conditionally delay NACK sending until next synch rcv */
2411 	if (l->nack_state == BC_NACK_SND_CONDITIONAL) {
2412 		l->nack_state = BC_NACK_SND_UNCONDITIONAL;
2413 		if ((peers_snd_nxt - l->rcv_nxt) < TIPC_MIN_LINK_WIN)
2414 			return 0;
2415 	}
2416 
2417 	/* Send NACK now but suppress next one */
2418 	tipc_link_build_bc_proto_msg(l, true, peers_snd_nxt, xmitq);
2419 	l->nack_state = BC_NACK_SND_SUPPRESS;
2420 	return 0;
2421 }
2422 
2423 int tipc_link_bc_ack_rcv(struct tipc_link *r, u16 acked, u16 gap,
2424 			 struct tipc_gap_ack_blks *ga,
2425 			 struct sk_buff_head *xmitq,
2426 			 struct sk_buff_head *retrq)
2427 {
2428 	struct tipc_link *l = r->bc_sndlink;
2429 	bool unused = false;
2430 	int rc = 0;
2431 
2432 	if (!link_is_up(r) || !r->bc_peer_is_up)
2433 		return 0;
2434 
2435 	if (gap) {
2436 		l->stats.recv_nacks++;
2437 		r->stats.recv_nacks++;
2438 	}
2439 
2440 	if (less(acked, r->acked) || (acked == r->acked && !gap && !ga))
2441 		return 0;
2442 
2443 	trace_tipc_link_bc_ack(r, acked, gap, &l->transmq);
2444 	tipc_link_advance_transmq(l, r, acked, gap, ga, retrq, &unused, &rc);
2445 
2446 	tipc_link_advance_backlog(l, xmitq);
2447 	if (unlikely(!skb_queue_empty(&l->wakeupq)))
2448 		link_prepare_wakeup(l);
2449 
2450 	return rc;
2451 }
2452 
2453 /* tipc_link_bc_nack_rcv(): receive broadcast nack message
2454  * This function is here for backwards compatibility, since
2455  * no BCAST_PROTOCOL/STATE messages occur from TIPC v2.5.
2456  */
2457 int tipc_link_bc_nack_rcv(struct tipc_link *l, struct sk_buff *skb,
2458 			  struct sk_buff_head *xmitq)
2459 {
2460 	struct tipc_msg *hdr = buf_msg(skb);
2461 	u32 dnode = msg_destnode(hdr);
2462 	int mtyp = msg_type(hdr);
2463 	u16 acked = msg_bcast_ack(hdr);
2464 	u16 from = acked + 1;
2465 	u16 to = msg_bcgap_to(hdr);
2466 	u16 peers_snd_nxt = to + 1;
2467 	int rc = 0;
2468 
2469 	kfree_skb(skb);
2470 
2471 	if (!tipc_link_is_up(l) || !l->bc_peer_is_up)
2472 		return 0;
2473 
2474 	if (mtyp != STATE_MSG)
2475 		return 0;
2476 
2477 	if (dnode == tipc_own_addr(l->net)) {
2478 		rc = tipc_link_bc_ack_rcv(l, acked, to - acked, NULL, xmitq,
2479 					  xmitq);
2480 		l->stats.recv_nacks++;
2481 		return rc;
2482 	}
2483 
2484 	/* Msg for other node => suppress own NACK at next sync if applicable */
2485 	if (more(peers_snd_nxt, l->rcv_nxt) && !less(l->rcv_nxt, from))
2486 		l->nack_state = BC_NACK_SND_SUPPRESS;
2487 
2488 	return 0;
2489 }
2490 
2491 void tipc_link_set_queue_limits(struct tipc_link *l, u32 min_win, u32 max_win)
2492 {
2493 	int max_bulk = TIPC_MAX_PUBL / (l->mtu / ITEM_SIZE);
2494 
2495 	l->min_win = min_win;
2496 	l->ssthresh = max_win;
2497 	l->max_win = max_win;
2498 	l->window = min_win;
2499 	l->backlog[TIPC_LOW_IMPORTANCE].limit      = min_win * 2;
2500 	l->backlog[TIPC_MEDIUM_IMPORTANCE].limit   = min_win * 4;
2501 	l->backlog[TIPC_HIGH_IMPORTANCE].limit     = min_win * 6;
2502 	l->backlog[TIPC_CRITICAL_IMPORTANCE].limit = min_win * 8;
2503 	l->backlog[TIPC_SYSTEM_IMPORTANCE].limit   = max_bulk;
2504 }
2505 
2506 /**
2507  * link_reset_stats - reset link statistics
2508  * @l: pointer to link
2509  */
2510 void tipc_link_reset_stats(struct tipc_link *l)
2511 {
2512 	memset(&l->stats, 0, sizeof(l->stats));
2513 }
2514 
2515 static void link_print(struct tipc_link *l, const char *str)
2516 {
2517 	struct sk_buff *hskb = skb_peek(&l->transmq);
2518 	u16 head = hskb ? msg_seqno(buf_msg(hskb)) : l->snd_nxt - 1;
2519 	u16 tail = l->snd_nxt - 1;
2520 
2521 	pr_info("%s Link <%s> state %x\n", str, l->name, l->state);
2522 	pr_info("XMTQ: %u [%u-%u], BKLGQ: %u, SNDNX: %u, RCVNX: %u\n",
2523 		skb_queue_len(&l->transmq), head, tail,
2524 		skb_queue_len(&l->backlogq), l->snd_nxt, l->rcv_nxt);
2525 }
2526 
2527 /* Parse and validate nested (link) properties valid for media, bearer and link
2528  */
2529 int tipc_nl_parse_link_prop(struct nlattr *prop, struct nlattr *props[])
2530 {
2531 	int err;
2532 
2533 	err = nla_parse_nested_deprecated(props, TIPC_NLA_PROP_MAX, prop,
2534 					  tipc_nl_prop_policy, NULL);
2535 	if (err)
2536 		return err;
2537 
2538 	if (props[TIPC_NLA_PROP_PRIO]) {
2539 		u32 prio;
2540 
2541 		prio = nla_get_u32(props[TIPC_NLA_PROP_PRIO]);
2542 		if (prio > TIPC_MAX_LINK_PRI)
2543 			return -EINVAL;
2544 	}
2545 
2546 	if (props[TIPC_NLA_PROP_TOL]) {
2547 		u32 tol;
2548 
2549 		tol = nla_get_u32(props[TIPC_NLA_PROP_TOL]);
2550 		if ((tol < TIPC_MIN_LINK_TOL) || (tol > TIPC_MAX_LINK_TOL))
2551 			return -EINVAL;
2552 	}
2553 
2554 	if (props[TIPC_NLA_PROP_WIN]) {
2555 		u32 max_win;
2556 
2557 		max_win = nla_get_u32(props[TIPC_NLA_PROP_WIN]);
2558 		if (max_win < TIPC_DEF_LINK_WIN || max_win > TIPC_MAX_LINK_WIN)
2559 			return -EINVAL;
2560 	}
2561 
2562 	return 0;
2563 }
2564 
2565 static int __tipc_nl_add_stats(struct sk_buff *skb, struct tipc_stats *s)
2566 {
2567 	int i;
2568 	struct nlattr *stats;
2569 
2570 	struct nla_map {
2571 		u32 key;
2572 		u32 val;
2573 	};
2574 
2575 	struct nla_map map[] = {
2576 		{TIPC_NLA_STATS_RX_INFO, 0},
2577 		{TIPC_NLA_STATS_RX_FRAGMENTS, s->recv_fragments},
2578 		{TIPC_NLA_STATS_RX_FRAGMENTED, s->recv_fragmented},
2579 		{TIPC_NLA_STATS_RX_BUNDLES, s->recv_bundles},
2580 		{TIPC_NLA_STATS_RX_BUNDLED, s->recv_bundled},
2581 		{TIPC_NLA_STATS_TX_INFO, 0},
2582 		{TIPC_NLA_STATS_TX_FRAGMENTS, s->sent_fragments},
2583 		{TIPC_NLA_STATS_TX_FRAGMENTED, s->sent_fragmented},
2584 		{TIPC_NLA_STATS_TX_BUNDLES, s->sent_bundles},
2585 		{TIPC_NLA_STATS_TX_BUNDLED, s->sent_bundled},
2586 		{TIPC_NLA_STATS_MSG_PROF_TOT, (s->msg_length_counts) ?
2587 			s->msg_length_counts : 1},
2588 		{TIPC_NLA_STATS_MSG_LEN_CNT, s->msg_length_counts},
2589 		{TIPC_NLA_STATS_MSG_LEN_TOT, s->msg_lengths_total},
2590 		{TIPC_NLA_STATS_MSG_LEN_P0, s->msg_length_profile[0]},
2591 		{TIPC_NLA_STATS_MSG_LEN_P1, s->msg_length_profile[1]},
2592 		{TIPC_NLA_STATS_MSG_LEN_P2, s->msg_length_profile[2]},
2593 		{TIPC_NLA_STATS_MSG_LEN_P3, s->msg_length_profile[3]},
2594 		{TIPC_NLA_STATS_MSG_LEN_P4, s->msg_length_profile[4]},
2595 		{TIPC_NLA_STATS_MSG_LEN_P5, s->msg_length_profile[5]},
2596 		{TIPC_NLA_STATS_MSG_LEN_P6, s->msg_length_profile[6]},
2597 		{TIPC_NLA_STATS_RX_STATES, s->recv_states},
2598 		{TIPC_NLA_STATS_RX_PROBES, s->recv_probes},
2599 		{TIPC_NLA_STATS_RX_NACKS, s->recv_nacks},
2600 		{TIPC_NLA_STATS_RX_DEFERRED, s->deferred_recv},
2601 		{TIPC_NLA_STATS_TX_STATES, s->sent_states},
2602 		{TIPC_NLA_STATS_TX_PROBES, s->sent_probes},
2603 		{TIPC_NLA_STATS_TX_NACKS, s->sent_nacks},
2604 		{TIPC_NLA_STATS_TX_ACKS, s->sent_acks},
2605 		{TIPC_NLA_STATS_RETRANSMITTED, s->retransmitted},
2606 		{TIPC_NLA_STATS_DUPLICATES, s->duplicates},
2607 		{TIPC_NLA_STATS_LINK_CONGS, s->link_congs},
2608 		{TIPC_NLA_STATS_MAX_QUEUE, s->max_queue_sz},
2609 		{TIPC_NLA_STATS_AVG_QUEUE, s->queue_sz_counts ?
2610 			(s->accu_queue_sz / s->queue_sz_counts) : 0}
2611 	};
2612 
2613 	stats = nla_nest_start_noflag(skb, TIPC_NLA_LINK_STATS);
2614 	if (!stats)
2615 		return -EMSGSIZE;
2616 
2617 	for (i = 0; i <  ARRAY_SIZE(map); i++)
2618 		if (nla_put_u32(skb, map[i].key, map[i].val))
2619 			goto msg_full;
2620 
2621 	nla_nest_end(skb, stats);
2622 
2623 	return 0;
2624 msg_full:
2625 	nla_nest_cancel(skb, stats);
2626 
2627 	return -EMSGSIZE;
2628 }
2629 
2630 /* Caller should hold appropriate locks to protect the link */
2631 int __tipc_nl_add_link(struct net *net, struct tipc_nl_msg *msg,
2632 		       struct tipc_link *link, int nlflags)
2633 {
2634 	u32 self = tipc_own_addr(net);
2635 	struct nlattr *attrs;
2636 	struct nlattr *prop;
2637 	void *hdr;
2638 	int err;
2639 
2640 	hdr = genlmsg_put(msg->skb, msg->portid, msg->seq, &tipc_genl_family,
2641 			  nlflags, TIPC_NL_LINK_GET);
2642 	if (!hdr)
2643 		return -EMSGSIZE;
2644 
2645 	attrs = nla_nest_start_noflag(msg->skb, TIPC_NLA_LINK);
2646 	if (!attrs)
2647 		goto msg_full;
2648 
2649 	if (nla_put_string(msg->skb, TIPC_NLA_LINK_NAME, link->name))
2650 		goto attr_msg_full;
2651 	if (nla_put_u32(msg->skb, TIPC_NLA_LINK_DEST, tipc_cluster_mask(self)))
2652 		goto attr_msg_full;
2653 	if (nla_put_u32(msg->skb, TIPC_NLA_LINK_MTU, link->mtu))
2654 		goto attr_msg_full;
2655 	if (nla_put_u32(msg->skb, TIPC_NLA_LINK_RX, link->stats.recv_pkts))
2656 		goto attr_msg_full;
2657 	if (nla_put_u32(msg->skb, TIPC_NLA_LINK_TX, link->stats.sent_pkts))
2658 		goto attr_msg_full;
2659 
2660 	if (tipc_link_is_up(link))
2661 		if (nla_put_flag(msg->skb, TIPC_NLA_LINK_UP))
2662 			goto attr_msg_full;
2663 	if (link->active)
2664 		if (nla_put_flag(msg->skb, TIPC_NLA_LINK_ACTIVE))
2665 			goto attr_msg_full;
2666 
2667 	prop = nla_nest_start_noflag(msg->skb, TIPC_NLA_LINK_PROP);
2668 	if (!prop)
2669 		goto attr_msg_full;
2670 	if (nla_put_u32(msg->skb, TIPC_NLA_PROP_PRIO, link->priority))
2671 		goto prop_msg_full;
2672 	if (nla_put_u32(msg->skb, TIPC_NLA_PROP_TOL, link->tolerance))
2673 		goto prop_msg_full;
2674 	if (nla_put_u32(msg->skb, TIPC_NLA_PROP_WIN,
2675 			link->window))
2676 		goto prop_msg_full;
2677 	if (nla_put_u32(msg->skb, TIPC_NLA_PROP_PRIO, link->priority))
2678 		goto prop_msg_full;
2679 	nla_nest_end(msg->skb, prop);
2680 
2681 	err = __tipc_nl_add_stats(msg->skb, &link->stats);
2682 	if (err)
2683 		goto attr_msg_full;
2684 
2685 	nla_nest_end(msg->skb, attrs);
2686 	genlmsg_end(msg->skb, hdr);
2687 
2688 	return 0;
2689 
2690 prop_msg_full:
2691 	nla_nest_cancel(msg->skb, prop);
2692 attr_msg_full:
2693 	nla_nest_cancel(msg->skb, attrs);
2694 msg_full:
2695 	genlmsg_cancel(msg->skb, hdr);
2696 
2697 	return -EMSGSIZE;
2698 }
2699 
2700 static int __tipc_nl_add_bc_link_stat(struct sk_buff *skb,
2701 				      struct tipc_stats *stats)
2702 {
2703 	int i;
2704 	struct nlattr *nest;
2705 
2706 	struct nla_map {
2707 		__u32 key;
2708 		__u32 val;
2709 	};
2710 
2711 	struct nla_map map[] = {
2712 		{TIPC_NLA_STATS_RX_INFO, stats->recv_pkts},
2713 		{TIPC_NLA_STATS_RX_FRAGMENTS, stats->recv_fragments},
2714 		{TIPC_NLA_STATS_RX_FRAGMENTED, stats->recv_fragmented},
2715 		{TIPC_NLA_STATS_RX_BUNDLES, stats->recv_bundles},
2716 		{TIPC_NLA_STATS_RX_BUNDLED, stats->recv_bundled},
2717 		{TIPC_NLA_STATS_TX_INFO, stats->sent_pkts},
2718 		{TIPC_NLA_STATS_TX_FRAGMENTS, stats->sent_fragments},
2719 		{TIPC_NLA_STATS_TX_FRAGMENTED, stats->sent_fragmented},
2720 		{TIPC_NLA_STATS_TX_BUNDLES, stats->sent_bundles},
2721 		{TIPC_NLA_STATS_TX_BUNDLED, stats->sent_bundled},
2722 		{TIPC_NLA_STATS_RX_NACKS, stats->recv_nacks},
2723 		{TIPC_NLA_STATS_RX_DEFERRED, stats->deferred_recv},
2724 		{TIPC_NLA_STATS_TX_NACKS, stats->sent_nacks},
2725 		{TIPC_NLA_STATS_TX_ACKS, stats->sent_acks},
2726 		{TIPC_NLA_STATS_RETRANSMITTED, stats->retransmitted},
2727 		{TIPC_NLA_STATS_DUPLICATES, stats->duplicates},
2728 		{TIPC_NLA_STATS_LINK_CONGS, stats->link_congs},
2729 		{TIPC_NLA_STATS_MAX_QUEUE, stats->max_queue_sz},
2730 		{TIPC_NLA_STATS_AVG_QUEUE, stats->queue_sz_counts ?
2731 			(stats->accu_queue_sz / stats->queue_sz_counts) : 0}
2732 	};
2733 
2734 	nest = nla_nest_start_noflag(skb, TIPC_NLA_LINK_STATS);
2735 	if (!nest)
2736 		return -EMSGSIZE;
2737 
2738 	for (i = 0; i <  ARRAY_SIZE(map); i++)
2739 		if (nla_put_u32(skb, map[i].key, map[i].val))
2740 			goto msg_full;
2741 
2742 	nla_nest_end(skb, nest);
2743 
2744 	return 0;
2745 msg_full:
2746 	nla_nest_cancel(skb, nest);
2747 
2748 	return -EMSGSIZE;
2749 }
2750 
2751 int tipc_nl_add_bc_link(struct net *net, struct tipc_nl_msg *msg,
2752 			struct tipc_link *bcl)
2753 {
2754 	int err;
2755 	void *hdr;
2756 	struct nlattr *attrs;
2757 	struct nlattr *prop;
2758 	u32 bc_mode = tipc_bcast_get_mode(net);
2759 	u32 bc_ratio = tipc_bcast_get_broadcast_ratio(net);
2760 
2761 	if (!bcl)
2762 		return 0;
2763 
2764 	tipc_bcast_lock(net);
2765 
2766 	hdr = genlmsg_put(msg->skb, msg->portid, msg->seq, &tipc_genl_family,
2767 			  NLM_F_MULTI, TIPC_NL_LINK_GET);
2768 	if (!hdr) {
2769 		tipc_bcast_unlock(net);
2770 		return -EMSGSIZE;
2771 	}
2772 
2773 	attrs = nla_nest_start_noflag(msg->skb, TIPC_NLA_LINK);
2774 	if (!attrs)
2775 		goto msg_full;
2776 
2777 	/* The broadcast link is always up */
2778 	if (nla_put_flag(msg->skb, TIPC_NLA_LINK_UP))
2779 		goto attr_msg_full;
2780 
2781 	if (nla_put_flag(msg->skb, TIPC_NLA_LINK_BROADCAST))
2782 		goto attr_msg_full;
2783 	if (nla_put_string(msg->skb, TIPC_NLA_LINK_NAME, bcl->name))
2784 		goto attr_msg_full;
2785 	if (nla_put_u32(msg->skb, TIPC_NLA_LINK_RX, 0))
2786 		goto attr_msg_full;
2787 	if (nla_put_u32(msg->skb, TIPC_NLA_LINK_TX, 0))
2788 		goto attr_msg_full;
2789 
2790 	prop = nla_nest_start_noflag(msg->skb, TIPC_NLA_LINK_PROP);
2791 	if (!prop)
2792 		goto attr_msg_full;
2793 	if (nla_put_u32(msg->skb, TIPC_NLA_PROP_WIN, bcl->max_win))
2794 		goto prop_msg_full;
2795 	if (nla_put_u32(msg->skb, TIPC_NLA_PROP_BROADCAST, bc_mode))
2796 		goto prop_msg_full;
2797 	if (bc_mode & BCLINK_MODE_SEL)
2798 		if (nla_put_u32(msg->skb, TIPC_NLA_PROP_BROADCAST_RATIO,
2799 				bc_ratio))
2800 			goto prop_msg_full;
2801 	nla_nest_end(msg->skb, prop);
2802 
2803 	err = __tipc_nl_add_bc_link_stat(msg->skb, &bcl->stats);
2804 	if (err)
2805 		goto attr_msg_full;
2806 
2807 	tipc_bcast_unlock(net);
2808 	nla_nest_end(msg->skb, attrs);
2809 	genlmsg_end(msg->skb, hdr);
2810 
2811 	return 0;
2812 
2813 prop_msg_full:
2814 	nla_nest_cancel(msg->skb, prop);
2815 attr_msg_full:
2816 	nla_nest_cancel(msg->skb, attrs);
2817 msg_full:
2818 	tipc_bcast_unlock(net);
2819 	genlmsg_cancel(msg->skb, hdr);
2820 
2821 	return -EMSGSIZE;
2822 }
2823 
2824 void tipc_link_set_tolerance(struct tipc_link *l, u32 tol,
2825 			     struct sk_buff_head *xmitq)
2826 {
2827 	l->tolerance = tol;
2828 	if (l->bc_rcvlink)
2829 		l->bc_rcvlink->tolerance = tol;
2830 	if (link_is_up(l))
2831 		tipc_link_build_proto_msg(l, STATE_MSG, 0, 0, 0, tol, 0, xmitq);
2832 }
2833 
2834 void tipc_link_set_prio(struct tipc_link *l, u32 prio,
2835 			struct sk_buff_head *xmitq)
2836 {
2837 	l->priority = prio;
2838 	tipc_link_build_proto_msg(l, STATE_MSG, 0, 0, 0, 0, prio, xmitq);
2839 }
2840 
2841 void tipc_link_set_abort_limit(struct tipc_link *l, u32 limit)
2842 {
2843 	l->abort_limit = limit;
2844 }
2845 
2846 /**
2847  * tipc_link_dump - dump TIPC link data
2848  * @l: tipc link to be dumped
2849  * @dqueues: bitmask to decide if any link queue to be dumped?
2850  *           - TIPC_DUMP_NONE: don't dump link queues
2851  *           - TIPC_DUMP_TRANSMQ: dump link transmq queue
2852  *           - TIPC_DUMP_BACKLOGQ: dump link backlog queue
2853  *           - TIPC_DUMP_DEFERDQ: dump link deferd queue
2854  *           - TIPC_DUMP_INPUTQ: dump link input queue
2855  *           - TIPC_DUMP_WAKEUP: dump link wakeup queue
2856  *           - TIPC_DUMP_ALL: dump all the link queues above
2857  * @buf: returned buffer of dump data in format
2858  */
2859 int tipc_link_dump(struct tipc_link *l, u16 dqueues, char *buf)
2860 {
2861 	int i = 0;
2862 	size_t sz = (dqueues) ? LINK_LMAX : LINK_LMIN;
2863 	struct sk_buff_head *list;
2864 	struct sk_buff *hskb, *tskb;
2865 	u32 len;
2866 
2867 	if (!l) {
2868 		i += scnprintf(buf, sz, "link data: (null)\n");
2869 		return i;
2870 	}
2871 
2872 	i += scnprintf(buf, sz, "link data: %x", l->addr);
2873 	i += scnprintf(buf + i, sz - i, " %x", l->state);
2874 	i += scnprintf(buf + i, sz - i, " %u", l->in_session);
2875 	i += scnprintf(buf + i, sz - i, " %u", l->session);
2876 	i += scnprintf(buf + i, sz - i, " %u", l->peer_session);
2877 	i += scnprintf(buf + i, sz - i, " %u", l->snd_nxt);
2878 	i += scnprintf(buf + i, sz - i, " %u", l->rcv_nxt);
2879 	i += scnprintf(buf + i, sz - i, " %u", l->snd_nxt_state);
2880 	i += scnprintf(buf + i, sz - i, " %u", l->rcv_nxt_state);
2881 	i += scnprintf(buf + i, sz - i, " %x", l->peer_caps);
2882 	i += scnprintf(buf + i, sz - i, " %u", l->silent_intv_cnt);
2883 	i += scnprintf(buf + i, sz - i, " %u", l->rst_cnt);
2884 	i += scnprintf(buf + i, sz - i, " %u", 0);
2885 	i += scnprintf(buf + i, sz - i, " %u", 0);
2886 	i += scnprintf(buf + i, sz - i, " %u", l->acked);
2887 
2888 	list = &l->transmq;
2889 	len = skb_queue_len(list);
2890 	hskb = skb_peek(list);
2891 	tskb = skb_peek_tail(list);
2892 	i += scnprintf(buf + i, sz - i, " | %u %u %u", len,
2893 		       (hskb) ? msg_seqno(buf_msg(hskb)) : 0,
2894 		       (tskb) ? msg_seqno(buf_msg(tskb)) : 0);
2895 
2896 	list = &l->deferdq;
2897 	len = skb_queue_len(list);
2898 	hskb = skb_peek(list);
2899 	tskb = skb_peek_tail(list);
2900 	i += scnprintf(buf + i, sz - i, " | %u %u %u", len,
2901 		       (hskb) ? msg_seqno(buf_msg(hskb)) : 0,
2902 		       (tskb) ? msg_seqno(buf_msg(tskb)) : 0);
2903 
2904 	list = &l->backlogq;
2905 	len = skb_queue_len(list);
2906 	hskb = skb_peek(list);
2907 	tskb = skb_peek_tail(list);
2908 	i += scnprintf(buf + i, sz - i, " | %u %u %u", len,
2909 		       (hskb) ? msg_seqno(buf_msg(hskb)) : 0,
2910 		       (tskb) ? msg_seqno(buf_msg(tskb)) : 0);
2911 
2912 	list = l->inputq;
2913 	len = skb_queue_len(list);
2914 	hskb = skb_peek(list);
2915 	tskb = skb_peek_tail(list);
2916 	i += scnprintf(buf + i, sz - i, " | %u %u %u\n", len,
2917 		       (hskb) ? msg_seqno(buf_msg(hskb)) : 0,
2918 		       (tskb) ? msg_seqno(buf_msg(tskb)) : 0);
2919 
2920 	if (dqueues & TIPC_DUMP_TRANSMQ) {
2921 		i += scnprintf(buf + i, sz - i, "transmq: ");
2922 		i += tipc_list_dump(&l->transmq, false, buf + i);
2923 	}
2924 	if (dqueues & TIPC_DUMP_BACKLOGQ) {
2925 		i += scnprintf(buf + i, sz - i,
2926 			       "backlogq: <%u %u %u %u %u>, ",
2927 			       l->backlog[TIPC_LOW_IMPORTANCE].len,
2928 			       l->backlog[TIPC_MEDIUM_IMPORTANCE].len,
2929 			       l->backlog[TIPC_HIGH_IMPORTANCE].len,
2930 			       l->backlog[TIPC_CRITICAL_IMPORTANCE].len,
2931 			       l->backlog[TIPC_SYSTEM_IMPORTANCE].len);
2932 		i += tipc_list_dump(&l->backlogq, false, buf + i);
2933 	}
2934 	if (dqueues & TIPC_DUMP_DEFERDQ) {
2935 		i += scnprintf(buf + i, sz - i, "deferdq: ");
2936 		i += tipc_list_dump(&l->deferdq, false, buf + i);
2937 	}
2938 	if (dqueues & TIPC_DUMP_INPUTQ) {
2939 		i += scnprintf(buf + i, sz - i, "inputq: ");
2940 		i += tipc_list_dump(l->inputq, false, buf + i);
2941 	}
2942 	if (dqueues & TIPC_DUMP_WAKEUP) {
2943 		i += scnprintf(buf + i, sz - i, "wakeup: ");
2944 		i += tipc_list_dump(&l->wakeupq, false, buf + i);
2945 	}
2946 
2947 	return i;
2948 }
2949