aboutsummaryrefslogtreecommitdiff
path: root/net/tipc/subscr.c
blob: 18813acc6bef0d431f11e18290a9722c489ef2c6 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
/*
 * net/tipc/subscr.c: TIPC network topology service
 *
 * Copyright (c) 2000-2006, Ericsson AB
 * Copyright (c) 2005-2007, Wind River Systems
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. Neither the names of the copyright holders nor the names of its
 *    contributors may be used to endorse or promote products derived from
 *    this software without specific prior written permission.
 *
 * Alternatively, this software may be distributed under the terms of the
 * GNU General Public License ("GPL") version 2 as published by the Free
 * Software Foundation.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 */

#include "core.h"
#include "dbg.h"
#include "name_table.h"
#include "port.h"
#include "ref.h"
#include "subscr.h"

/**
 * struct subscriber - TIPC network topology subscriber
 * @port_ref: object reference to server port connecting to subscriber
 * @lock: pointer to spinlock controlling access to subscriber's server port
 * @subscriber_list: adjacent subscribers in top. server's list of subscribers
 * @subscription_list: list of subscription objects for this subscriber
 */

struct subscriber {
	u32 port_ref;
	spinlock_t *lock;
	struct list_head subscriber_list;
	struct list_head subscription_list;
};

/**
 * struct top_srv - TIPC network topology subscription service
 * @user_ref: TIPC userid of subscription service
 * @setup_port: reference to TIPC port that handles subscription requests
 * @subscription_count: number of active subscriptions (not subscribers!)
 * @subscriber_list: list of ports subscribing to service
 * @lock: spinlock govering access to subscriber list
 */

struct top_srv {
	u32 user_ref;
	u32 setup_port;
	atomic_t subscription_count;
	struct list_head subscriber_list;
	spinlock_t lock;
};

static struct top_srv topsrv = { 0 };

/**
 * subscr_send_event - send a message containing a tipc_event to the subscriber
 *
 * Note: Must not hold subscriber's server port lock, since tipc_send() will
 *       try to take the lock if the message is rejected and returned!
 */

static void subscr_send_event(struct subscription *sub,
			      u32 found_lower,
			      u32 found_upper,
			      u32 event,
			      u32 port_ref,
			      u32 node)
{
	struct iovec msg_sect;

	msg_sect.iov_base = (void *)&sub->evt;
	msg_sect.iov_len = sizeof(struct tipc_event);

	sub->evt.event = htonl(event);
	sub->evt.found_lower = htonl(found_lower);
	sub->evt.found_upper = htonl(found_upper);
	sub->evt.port.ref = htonl(port_ref);
	sub->evt.port.node = htonl(node);
	tipc_send(sub->server_ref, 1, &msg_sect);
}

/**
 * tipc_subscr_overlap - test for subscription overlap with the given values
 *
 * Returns 1 if there is overlap, otherwise 0.
 */

int tipc_subscr_overlap(struct subscription *sub,
			u32 found_lower,
			u32 found_upper)

{
	if (found_lower < sub->seq.lower)
		found_lower = sub->seq.lower;
	if (found_upper > sub->seq.upper)
		found_upper = sub->seq.upper;
	if (found_lower > found_upper)
		return 0;
	return 1;
}

/**
 * tipc_subscr_report_overlap - issue event if there is subscription overlap
 *
 * Protected by nameseq.lock in name_table.c
 */

void tipc_subscr_report_overlap(struct subscription *sub,
				u32 found_lower,
				u32 found_upper,
				u32 event,
				u32 port_ref,
				u32 node,
				int must)
{
	if (!tipc_subscr_overlap(sub, found_lower, found_upper))
		return;
	if (!must && !(sub->filter & TIPC_SUB_PORTS))
		return;

	sub->event_cb(sub, found_lower, found_upper, event, port_ref, node);
}

/**
 * subscr_timeout - subscription timeout has occurred
 */

static void subscr_timeout(struct subscription *sub)
{
	struct port *server_port;

	/* Validate server port reference (in case subscriber is terminating) */

	server_port = tipc_port_lock(sub->server_ref);
	if (server_port == NULL)
		return;

	/* Validate timeout (in case subscription is being cancelled) */

	if (sub->timeout == TIPC_WAIT_FOREVER) {
		tipc_port_unlock(server_port);
		return;
	}

	/* Unlink subscription from name table */

	tipc_nametbl_unsubscribe(sub);

	/* Unlink subscription from subscriber */

	list_del(&sub->subscription_list);

	/* Release subscriber's server port */

	tipc_port_unlock(server_port);

	/* Notify subscriber of timeout */

	subscr_send_event(sub, sub->evt.s.seq.lower, sub->evt.s.seq.upper,
			  TIPC_SUBSCR_TIMEOUT, 0, 0);

	/* Now destroy subscription */

	k_term_timer(&sub->timer);
	kfree(sub);
	atomic_dec(&topsrv.subscription_count);
}

/**
 * subscr_del - delete a subscription within a subscription list
 *
 * Called with subscriber port locked.
 */

static void subscr_del(struct subscription *sub)
{
	tipc_nametbl_unsubscribe(sub);
	list_del(&sub->subscription_list);
	kfree(sub);
	atomic_dec(&topsrv.subscription_count);
}

/**
 * subscr_terminate - terminate communication with a subscriber
 *
 * Called with subscriber port locked.  Routine must temporarily release lock
 * to enable subscription timeout routine(s) to finish without deadlocking;
 * the lock is then reclaimed to allow caller to release it upon return.
 * (This should work even in the unlikely event some other thread creates
 * a new object reference in the interim that uses this lock; this routine will
 * simply wait for it to be released, then claim it.)
 */

static void subscr_terminate(struct subscriber *subscriber)
{
	u32 port_ref;
	struct subscription *sub;
	struct subscription *sub_temp;

	/* Invalidate subscriber reference */

	port_ref = subscriber->port_ref;
	subscriber->port_ref = 0;
	spin_unlock_bh(subscriber->lock);

	/* Sever connection to subscriber */

	tipc_shutdown(port_ref);
	tipc_deleteport(port_ref);

	/* Destroy any existing subscriptions for subscriber */

	list_for_each_entry_safe(sub, sub_temp, &subscriber->subscription_list,
				 subscription_list) {
		if (sub->timeout != TIPC_WAIT_FOREVER) {
			k_cancel_timer(&sub->timer);
			k_term_timer(&sub->timer);
		}
		dbg("Term: Removing sub %u,%u,%u from subscriber %x list\n",
		    sub->seq.type, sub->seq.lower, sub->seq.upper, subscriber);
		subscr_del(sub);
	}

	/* Remove subscriber from topology server's subscriber list */

	spin_lock_bh(&topsrv.lock);
	list_del(&subscriber->subscriber_list);
	spin_unlock_bh(&topsrv.lock);

	/* Reclaim subscriber lock */

	spin_lock_bh(subscriber->lock);

	/* Now destroy subscriber */

	kfree(subscriber);
}

/**
 * subscr_cancel - handle subscription cancellation request
 *
 * Called with subscriber port locked.  Routine must temporarily release lock
 * to enable the subscription timeout routine to finish without deadlocking;
 * the lock is then reclaimed to allow caller to release it upon return.
 *
 * Note that fields of 's' use subscriber's endianness!
 */

static void subscr_cancel(struct tipc_subscr *s,
			  struct subscriber *subscriber)
{
	struct subscription *sub;
	struct subscription *sub_temp;
	__u32 type, lower, upper, timeout, filter;
	int found = 0;

	/* Find first matching subscription, exit if not found */

	type = ntohl(s->seq.type);
	lower = ntohl(s->seq.lower);
	upper = ntohl(s->seq.upper);
	timeout = ntohl(s->timeout);
	filter = ntohl(s->filter) & ~TIPC_SUB_CANCEL;

	list_for_each_entry_safe(sub, sub_temp, &subscriber->subscription_list,
				 subscription_list) {
			if ((type == sub->seq.type) &&
			    (lower == sub->seq.lower) &&
			    (upper == sub->seq.upper) &&
			    (timeout == sub->timeout) &&
                            (filter == sub->filter) &&
                             !memcmp(s->usr_handle,sub->evt.s.usr_handle,
				     sizeof(s->usr_handle)) ){
				found = 1;
				break;
			}
	}
	if (!found)
		return;

	/* Cancel subscription timer (if used), then delete subscription */

	if (sub->timeout != TIPC_WAIT_FOREVER) {
		sub->timeout = TIPC_WAIT_FOREVER;
		spin_unlock_bh(subscriber->lock);
		k_cancel_timer(&sub->timer);
		k_term_timer(&sub->timer);
		spin_lock_bh(subscriber->lock);
	}
	dbg("Cancel: removing sub %u,%u,%u from subscriber %p list\n",
	    sub->seq.type, sub->seq.lower, sub->seq.upper, subscriber);
	subscr_del(sub);
}

/**
 * subscr_subscribe - create subscription for subscriber
 *
 * Called with subscriber port locked.
 */

static struct subscription *subscr_subscribe(struct tipc_subscr *s,
					     struct subscriber *subscriber)
{
	struct subscription *sub;

	/* Detect & process a subscription cancellation request */

	if (ntohl(s->filter) & TIPC_SUB_CANCEL) {
		subscr_cancel(s, subscriber);
		return NULL;
	}

	/* Refuse subscription if global limit exceeded */

	if (atomic_read(&topsrv.subscription_count) >= tipc_max_subscriptions) {
		warn("Subscription rejected, subscription limit reached (%u)\n",
		     tipc_max_subscriptions);
		subscr_terminate(subscriber);
		return NULL;
	}

	/* Allocate subscription object */

	sub = kmalloc(sizeof(*sub), GFP_ATOMIC);
	if (!sub) {
		warn("Subscription rejected, no memory\n");
		subscr_terminate(subscriber);
		return NULL;
	}

	/* Initialize subscription object */

	sub->seq.type = ntohl(s->seq.type);
	sub->seq.lower = ntohl(s->seq.lower);
	sub->seq.upper = ntohl(s->seq.upper);
	sub->timeout = ntohl(s->timeout);
	sub->filter = ntohl(s->filter);
	if ((sub->filter && (sub->filter != TIPC_SUB_PORTS)) ||
	    (sub->seq.lower > sub->seq.upper)) {
		warn("Subscription rejected, illegal request\n");
		kfree(sub);
		subscr_terminate(subscriber);
		return NULL;
	}
	sub->event_cb = subscr_send_event;
	INIT_LIST_HEAD(&sub->nameseq_list);
	list_add(&sub->subscription_list, &subscriber->subscription_list);
	sub->server_ref = subscriber->port_ref;
	memcpy(&sub->evt.s, s, sizeof(struct tipc_subscr));
	atomic_inc(&topsrv.subscription_count);
	if (sub->timeout != TIPC_WAIT_FOREVER) {
		k_init_timer(&sub->timer,
			     (Handler)subscr_timeout, (unsigned long)sub);
		k_start_timer(&sub->timer, sub->timeout);
	}

	return sub;
}

/**
 * subscr_conn_shutdown_event - handle termination request from subscriber
 *
 * Called with subscriber's server port unlocked.
 */

static void subscr_conn_shutdown_event(void *usr_handle,
				       u32 port_ref,
				       struct sk_buff **buf,
				       unsigned char const *data,
				       unsigned int size,
				       int reason)
{
	struct subscriber *subscriber = usr_handle;
	spinlock_t *subscriber_lock;

	if (tipc_port_lock(port_ref) == NULL)
		return;

	subscriber_lock = subscriber->lock;
	subscr_terminate(subscriber);
	spin_unlock_bh(subscriber_lock);
}

/**
 * subscr_conn_msg_event - handle new subscription request from subscriber
 *
 * Called with subscriber's server port unlocked.
 */

static void subscr_conn_msg_event(void *usr_handle,
				  u32 port_ref,
				  struct sk_buff **buf,
				  const unchar *data,
				  u32 size)
{
	struct subscriber *subscriber = usr_handle;
	spinlock_t *subscriber_lock;
	struct subscription *sub;

	/*
	 * Lock subscriber's server port (& make a local copy of lock pointer,
	 * in case subscriber is deleted while processing subscription request)
	 */

	if (tipc_port_lock(port_ref) == NULL)
		return;

	subscriber_lock = subscriber->lock;

	if (size != sizeof(struct tipc_subscr)) {
		subscr_terminate(subscriber);
		spin_unlock_bh(subscriber_lock);
	} else {
		sub = subscr_subscribe((struct tipc_subscr *)data, subscriber);
		spin_unlock_bh(subscriber_lock);
		if (sub != NULL) {

			/*
			 * We must release the server port lock before adding a
			 * subscription to the name table since TIPC needs to be
			 * able to (re)acquire the port lock if an event message
			 * issued by the subscription process is rejected and
			 * returned.  The subscription cannot be deleted while
			 * it is being added to the name table because:
			 * a) the single-threading of the native API port code
			 *    ensures the subscription cannot be cancelled and
			 *    the subscriber connection cannot be broken, and
			 * b) the name table lock ensures the subscription
			 *    timeout code cannot delete the subscription,
			 * so the subscription object is still protected.
			 */

			tipc_nametbl_subscribe(sub);
		}
	}
}

/**
 * subscr_named_msg_event - handle request to establish a new subscriber
 */

static void subscr_named_msg_event(void *usr_handle,
				   u32 port_ref,
				   struct sk_buff **buf,
				   const unchar *data,
				   u32 size,
				   u32 importance,
				   struct tipc_portid const *orig,
				   struct tipc_name_seq const *dest)
{
	static struct iovec msg_sect = {NULL, 0};

	struct subscriber *subscriber;
	u32 server_port_ref;

	/* Create subscriber object */

	subscriber = kzalloc(sizeof(struct subscriber), GFP_ATOMIC);
	if (subscriber == NULL) {
		warn("Subscriber rejected, no memory\n");
		return;
	}
	INIT_LIST_HEAD(&subscriber->subscription_list);
	INIT_LIST_HEAD(&subscriber->subscriber_list);

	/* Create server port & establish connection to subscriber */

	tipc_createport(topsrv.user_ref,
			subscriber,
			importance,
			NULL,
			NULL,
			subscr_conn_shutdown_event,
			NULL,
			NULL,
			subscr_conn_msg_event,
			NULL,
			&subscriber->port_ref);
	if (subscriber->port_ref == 0) {
		warn("Subscriber rejected, unable to create port\n");
		kfree(subscriber);
		return;
	}
	tipc_connect2port(subscriber->port_ref, orig);

	/* Lock server port (& save lock address for future use) */

	subscriber->lock = tipc_port_lock(subscriber->port_ref)->publ.lock;

	/* Add subscriber to topology server's subscriber list */

	spin_lock_bh(&topsrv.lock);
	list_add(&subscriber->subscriber_list, &topsrv.subscriber_list);
	spin_unlock_bh(&topsrv.lock);

	/* Unlock server port */

	server_port_ref = subscriber->port_ref;
	spin_unlock_bh(subscriber->lock);

	/* Send an ACK- to complete connection handshaking */

	tipc_send(server_port_ref, 1, &msg_sect);

	/* Handle optional subscription request */

	if (size != 0) {
		subscr_conn_msg_event(subscriber, server_port_ref,
				      buf, data, size);
	}
}

int tipc_subscr_start(void)
{
	struct tipc_name_seq seq = {TIPC_TOP_SRV, TIPC_TOP_SRV, TIPC_TOP_SRV};
	int res = -1;

	memset(&topsrv, 0, sizeof (topsrv));
	spin_lock_init(&topsrv.lock);
	INIT_LIST_HEAD(&topsrv.subscriber_list);

	spin_lock_bh(&topsrv.lock);
	res = tipc_attach(&topsrv.user_ref, NULL, NULL);
	if (res) {
		spin_unlock_bh(&topsrv.lock);
		return res;
	}

	res = tipc_createport(topsrv.user_ref,
			      NULL,
			      TIPC_CRITICAL_IMPORTANCE,
			      NULL,
			      NULL,
			      NULL,
			      NULL,
			      subscr_named_msg_event,
			      NULL,
			      NULL,
			      &topsrv.setup_port);
	if (res)
		goto failed;

	res = tipc_nametbl_publish_rsv(topsrv.setup_port, TIPC_NODE_SCOPE, &seq);
	if (res)
		goto failed;

	spin_unlock_bh(&topsrv.lock);
	return 0;

failed:
	err("Failed to create subscription service\n");
	tipc_detach(topsrv.user_ref);
	topsrv.user_ref = 0;
	spin_unlock_bh(&topsrv.lock);
	return res;
}

void tipc_subscr_stop(void)
{
	struct subscriber *subscriber;
	struct subscriber *subscriber_temp;
	spinlock_t *subscriber_lock;

	if (topsrv.user_ref) {
		tipc_deleteport(topsrv.setup_port);
		list_for_each_entry_safe(subscriber, subscriber_temp,
					 &topsrv.subscriber_list,
					 subscriber_list) {
			subscriber_lock = subscriber->lock;
			spin_lock_bh(subscriber_lock);
			subscr_terminate(subscriber);
			spin_unlock_bh(subscriber_lock);
		}
		tipc_detach(topsrv.user_ref);
		topsrv.user_ref = 0;
	}
}