aboutsummaryrefslogtreecommitdiff
path: root/net/tipc/topsrv.c
blob: 3a12fc18239b8184526b027ee9b3afce5893f717 (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
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
/*
 * net/tipc/server.c: TIPC server infrastructure
 *
 * Copyright (c) 2012-2013, Wind River Systems
 * Copyright (c) 2017-2018, Ericsson AB
 * 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 "subscr.h"
#include "topsrv.h"
#include "core.h"
#include "socket.h"
#include "addr.h"
#include "msg.h"
#include "bearer.h"
#include <net/sock.h>
#include <linux/module.h>

/* Number of messages to send before rescheduling */
#define MAX_SEND_MSG_COUNT	25
#define MAX_RECV_MSG_COUNT	25
#define CF_CONNECTED		1
#define CF_SERVER		2

#define TIPC_SERVER_NAME_LEN	32

/**
 * struct tipc_topsrv - TIPC server structure
 * @conn_idr: identifier set of connection
 * @idr_lock: protect the connection identifier set
 * @idr_in_use: amount of allocated identifier entry
 * @net: network namspace instance
 * @awork: accept work item
 * @rcv_wq: receive workqueue
 * @send_wq: send workqueue
 * @listener: topsrv listener socket
 * @name: server name
 */
struct tipc_topsrv {
	struct idr conn_idr;
	spinlock_t idr_lock; /* for idr list */
	int idr_in_use;
	struct net *net;
	struct work_struct awork;
	struct workqueue_struct *rcv_wq;
	struct workqueue_struct *send_wq;
	struct socket *listener;
	char name[TIPC_SERVER_NAME_LEN];
};

/**
 * struct tipc_conn - TIPC connection structure
 * @kref: reference counter to connection object
 * @conid: connection identifier
 * @sock: socket handler associated with connection
 * @flags: indicates connection state
 * @server: pointer to connected server
 * @sub_list: lsit to all pertaing subscriptions
 * @sub_lock: lock protecting the subscription list
 * @rwork: receive work item
 * @outqueue: pointer to first outbound message in queue
 * @outqueue_lock: control access to the outqueue
 * @swork: send work item
 */
struct tipc_conn {
	struct kref kref;
	int conid;
	struct socket *sock;
	unsigned long flags;
	struct tipc_topsrv *server;
	struct list_head sub_list;
	spinlock_t sub_lock; /* for subscription list */
	struct work_struct rwork;
	struct list_head outqueue;
	spinlock_t outqueue_lock; /* for outqueue */
	struct work_struct swork;
};

/* An entry waiting to be sent */
struct outqueue_entry {
	bool inactive;
	struct tipc_event evt;
	struct list_head list;
};

static void tipc_conn_recv_work(struct work_struct *work);
static void tipc_conn_send_work(struct work_struct *work);
static void tipc_topsrv_kern_evt(struct net *net, struct tipc_event *evt);
static void tipc_conn_delete_sub(struct tipc_conn *con, struct tipc_subscr *s);

static bool connected(struct tipc_conn *con)
{
	return con && test_bit(CF_CONNECTED, &con->flags);
}

static void tipc_conn_kref_release(struct kref *kref)
{
	struct tipc_conn *con = container_of(kref, struct tipc_conn, kref);
	struct tipc_topsrv *s = con->server;
	struct outqueue_entry *e, *safe;

	spin_lock_bh(&s->idr_lock);
	idr_remove(&s->conn_idr, con->conid);
	s->idr_in_use--;
	spin_unlock_bh(&s->idr_lock);
	if (con->sock)
		sock_release(con->sock);

	spin_lock_bh(&con->outqueue_lock);
	list_for_each_entry_safe(e, safe, &con->outqueue, list) {
		list_del(&e->list);
		kfree(e);
	}
	spin_unlock_bh(&con->outqueue_lock);
	kfree(con);
}

static void conn_put(struct tipc_conn *con)
{
	kref_put(&con->kref, tipc_conn_kref_release);
}

static void conn_get(struct tipc_conn *con)
{
	kref_get(&con->kref);
}

static void tipc_conn_close(struct tipc_conn *con)
{
	struct sock *sk = con->sock->sk;
	bool disconnect = false;

	write_lock_bh(&sk->sk_callback_lock);
	disconnect = test_and_clear_bit(CF_CONNECTED, &con->flags);

	if (disconnect) {
		sk->sk_user_data = NULL;
		tipc_conn_delete_sub(con, NULL);
	}
	write_unlock_bh(&sk->sk_callback_lock);

	/* Handle concurrent calls from sending and receiving threads */
	if (!disconnect)
		return;

	/* Don't flush pending works, -just let them expire */
	kernel_sock_shutdown(con->sock, SHUT_RDWR);

	conn_put(con);
}

static struct tipc_conn *tipc_conn_alloc(struct tipc_topsrv *s)
{
	struct tipc_conn *con;
	int ret;

	con = kzalloc(sizeof(*con), GFP_ATOMIC);
	if (!con)
		return ERR_PTR(-ENOMEM);

	kref_init(&con->kref);
	INIT_LIST_HEAD(&con->outqueue);
	INIT_LIST_HEAD(&con->sub_list);
	spin_lock_init(&con->outqueue_lock);
	spin_lock_init(&con->sub_lock);
	INIT_WORK(&con->swork, tipc_conn_send_work);
	INIT_WORK(&con->rwork, tipc_conn_recv_work);

	spin_lock_bh(&s->idr_lock);
	ret = idr_alloc(&s->conn_idr, con, 0, 0, GFP_ATOMIC);
	if (ret < 0) {
		kfree(con);
		spin_unlock_bh(&s->idr_lock);
		return ERR_PTR(-ENOMEM);
	}
	con->conid = ret;
	s->idr_in_use++;
	spin_unlock_bh(&s->idr_lock);

	set_bit(CF_CONNECTED, &con->flags);
	con->server = s;

	return con;
}

static struct tipc_conn *tipc_conn_lookup(struct tipc_topsrv *s, int conid)
{
	struct tipc_conn *con;

	spin_lock_bh(&s->idr_lock);
	con = idr_find(&s->conn_idr, conid);
	if (!connected(con) || !kref_get_unless_zero(&con->kref))
		con = NULL;
	spin_unlock_bh(&s->idr_lock);
	return con;
}

/* tipc_conn_delete_sub - delete a specific or all subscriptions
 * for a given subscriber
 */
static void tipc_conn_delete_sub(struct tipc_conn *con, struct tipc_subscr *s)
{
	struct tipc_net *tn = tipc_net(con->server->net);
	struct list_head *sub_list = &con->sub_list;
	struct tipc_subscription *sub, *tmp;

	spin_lock_bh(&con->sub_lock);
	list_for_each_entry_safe(sub, tmp, sub_list, sub_list) {
		if (!s || !memcmp(s, &sub->evt.s, sizeof(*s))) {
			tipc_sub_unsubscribe(sub);
			atomic_dec(&tn->subscription_count);
		} else if (s) {
			break;
		}
	}
	spin_unlock_bh(&con->sub_lock);
}

static void tipc_conn_send_to_sock(struct tipc_conn *con)
{
	struct list_head *queue = &con->outqueue;
	struct tipc_topsrv *srv = con->server;
	struct outqueue_entry *e;
	struct tipc_event *evt;
	struct msghdr msg;
	struct kvec iov;
	int count = 0;
	int ret;

	spin_lock_bh(&con->outqueue_lock);

	while (!list_empty(queue)) {
		e = list_first_entry(queue, struct outqueue_entry, list);
		evt = &e->evt;
		spin_unlock_bh(&con->outqueue_lock);

		if (e->inactive)
			tipc_conn_delete_sub(con, &evt->s);

		memset(&msg, 0, sizeof(msg));
		msg.msg_flags = MSG_DONTWAIT;
		iov.iov_base = evt;
		iov.iov_len = sizeof(*evt);
		msg.msg_name = NULL;

		if (con->sock) {
			ret = kernel_sendmsg(con->sock, &msg, &iov,
					     1, sizeof(*evt));
			if (ret == -EWOULDBLOCK || ret == 0) {
				cond_resched();
				return;
			} else if (ret < 0) {
				return tipc_conn_close(con);
			}
		} else {
			tipc_topsrv_kern_evt(srv->net, evt);
		}

		/* Don't starve users filling buffers */
		if (++count >= MAX_SEND_MSG_COUNT) {
			cond_resched();
			count = 0;
		}
		spin_lock_bh(&con->outqueue_lock);
		list_del(&e->list);
		kfree(e);
	}
	spin_unlock_bh(&con->outqueue_lock);
}

static void tipc_conn_send_work(struct work_struct *work)
{
	struct tipc_conn *con = container_of(work, struct tipc_conn, swork);

	if (connected(con))
		tipc_conn_send_to_sock(con);

	conn_put(con);
}

/* tipc_topsrv_queue_evt() - interrupt level call from a subscription instance
 * The queued work is launched into tipc_conn_send_work()->tipc_conn_send_to_sock()
 */
void tipc_topsrv_queue_evt(struct net *net, int conid,
			   u32 event, struct tipc_event *evt)
{
	struct tipc_topsrv *srv = tipc_topsrv(net);
	struct outqueue_entry *e;
	struct tipc_conn *con;

	con = tipc_conn_lookup(srv, conid);
	if (!con)
		return;

	if (!connected(con))
		goto err;

	e = kmalloc(sizeof(*e), GFP_ATOMIC);
	if (!e)
		goto err;
	e->inactive = (event == TIPC_SUBSCR_TIMEOUT);
	memcpy(&e->evt, evt, sizeof(*evt));
	spin_lock_bh(&con->outqueue_lock);
	list_add_tail(&e->list, &con->outqueue);
	spin_unlock_bh(&con->outqueue_lock);

	if (queue_work(srv->send_wq, &con->swork))
		return;
err:
	conn_put(con);
}

/* tipc_conn_write_space - interrupt callback after a sendmsg EAGAIN
 * Indicates that there now is more space in the send buffer
 * The queued work is launched into tipc_send_work()->tipc_conn_send_to_sock()
 */
static void tipc_conn_write_space(struct sock *sk)
{
	struct tipc_conn *con;

	read_lock_bh(&sk->sk_callback_lock);
	con = sk->sk_user_data;
	if (connected(con)) {
		conn_get(con);
		if (!queue_work(con->server->send_wq, &con->swork))
			conn_put(con);
	}
	read_unlock_bh(&sk->sk_callback_lock);
}

static int tipc_conn_rcv_sub(struct tipc_topsrv *srv,
			     struct tipc_conn *con,
			     struct tipc_subscr *s)
{
	struct tipc_net *tn = tipc_net(srv->net);
	struct tipc_subscription *sub;

	if (tipc_sub_read(s, filter) & TIPC_SUB_CANCEL) {
		s->filter &= __constant_ntohl(~TIPC_SUB_CANCEL);
		tipc_conn_delete_sub(con, s);
		return 0;
	}
	if (atomic_read(&tn->subscription_count) >= TIPC_MAX_SUBSCR) {
		pr_warn("Subscription rejected, max (%u)\n", TIPC_MAX_SUBSCR);
		return -1;
	}
	sub = tipc_sub_subscribe(srv->net, s, con->conid);
	if (!sub)
		return -1;
	atomic_inc(&tn->subscription_count);
	spin_lock_bh(&con->sub_lock);
	list_add(&sub->sub_list, &con->sub_list);
	spin_unlock_bh(&con->sub_lock);
	return 0;
}

static int tipc_conn_rcv_from_sock(struct tipc_conn *con)
{
	struct tipc_topsrv *srv = con->server;
	struct sock *sk = con->sock->sk;
	struct msghdr msg = {};
	struct tipc_subscr s;
	struct kvec iov;
	int ret;

	iov.iov_base = &s;
	iov.iov_len = sizeof(s);
	msg.msg_name = NULL;
	iov_iter_kvec(&msg.msg_iter, READ, &iov, 1, iov.iov_len);
	ret = sock_recvmsg(con->sock, &msg, MSG_DONTWAIT);
	if (ret == -EWOULDBLOCK)
		return -EWOULDBLOCK;
	if (ret == sizeof(s)) {
		read_lock_bh(&sk->sk_callback_lock);
		ret = tipc_conn_rcv_sub(srv, con, &s);
		read_unlock_bh(&sk->sk_callback_lock);
	}
	if (ret < 0)
		tipc_conn_close(con);

	return ret;
}

static void tipc_conn_recv_work(struct work_struct *work)
{
	struct tipc_conn *con = container_of(work, struct tipc_conn, rwork);
	int count = 0;

	while (connected(con)) {
		if (tipc_conn_rcv_from_sock(con))
			break;

		/* Don't flood Rx machine */
		if (++count >= MAX_RECV_MSG_COUNT) {
			cond_resched();
			count = 0;
		}
	}
	conn_put(con);
}

/* tipc_conn_data_ready - interrupt callback indicating the socket has data
 * The queued work is launched into tipc_recv_work()->tipc_conn_rcv_from_sock()
 */
static void tipc_conn_data_ready(struct sock *sk)
{
	struct tipc_conn *con;

	read_lock_bh(&sk->sk_callback_lock);
	con = sk->sk_user_data;
	if (connected(con)) {
		conn_get(con);
		if (!queue_work(con->server->rcv_wq, &con->rwork))
			conn_put(con);
	}
	read_unlock_bh(&sk->sk_callback_lock);
}

static void tipc_topsrv_accept(struct work_struct *work)
{
	struct tipc_topsrv *srv = container_of(work, struct tipc_topsrv, awork);
	struct socket *lsock = srv->listener;
	struct socket *newsock;
	struct tipc_conn *con;
	struct sock *newsk;
	int ret;

	while (1) {
		ret = kernel_accept(lsock, &newsock, O_NONBLOCK);
		if (ret < 0)
			return;
		con = tipc_conn_alloc(srv);
		if (IS_ERR(con)) {
			ret = PTR_ERR(con);
			sock_release(newsock);
			return;
		}
		/* Register callbacks */
		newsk = newsock->sk;
		write_lock_bh(&newsk->sk_callback_lock);
		newsk->sk_data_ready = tipc_conn_data_ready;
		newsk->sk_write_space = tipc_conn_write_space;
		newsk->sk_user_data = con;
		con->sock = newsock;
		write_unlock_bh(&newsk->sk_callback_lock);

		/* Wake up receive process in case of 'SYN+' message */
		newsk->sk_data_ready(newsk);
	}
}

/* tipc_topsrv_listener_data_ready - interrupt callback with connection request
 * The queued job is launched into tipc_topsrv_accept()
 */
static void tipc_topsrv_listener_data_ready(struct sock *sk)
{
	struct tipc_topsrv *srv;

	read_lock_bh(&sk->sk_callback_lock);
	srv = sk->sk_user_data;
	if (srv->listener)
		queue_work(srv->rcv_wq, &srv->awork);
	read_unlock_bh(&sk->sk_callback_lock);
}

static int tipc_topsrv_create_listener(struct tipc_topsrv *srv)
{
	int imp = TIPC_CRITICAL_IMPORTANCE;
	struct socket *lsock = NULL;
	struct sockaddr_tipc saddr;
	struct sock *sk;
	int rc;

	rc = sock_create_kern(srv->net, AF_TIPC, SOCK_SEQPACKET, 0, &lsock);
	if (rc < 0)
		return rc;

	srv->listener = lsock;
	sk = lsock->sk;
	write_lock_bh(&sk->sk_callback_lock);
	sk->sk_data_ready = tipc_topsrv_listener_data_ready;
	sk->sk_user_data = srv;
	write_unlock_bh(&sk->sk_callback_lock);

	rc = kernel_setsockopt(lsock, SOL_TIPC, TIPC_IMPORTANCE,
			       (char *)&imp, sizeof(imp));
	if (rc < 0)
		goto err;

	saddr.family	                = AF_TIPC;
	saddr.addrtype		        = TIPC_ADDR_NAMESEQ;
	saddr.addr.nameseq.type	        = TIPC_TOP_SRV;
	saddr.addr.nameseq.lower	= TIPC_TOP_SRV;
	saddr.addr.nameseq.upper	= TIPC_TOP_SRV;
	saddr.scope			= TIPC_NODE_SCOPE;

	rc = kernel_bind(lsock, (struct sockaddr *)&saddr, sizeof(saddr));
	if (rc < 0)
		goto err;
	rc = kernel_listen(lsock, 0);
	if (rc < 0)
		goto err;

	/* As server's listening socket owner and creator is the same module,
	 * we have to decrease TIPC module reference count to guarantee that
	 * it remains zero after the server socket is created, otherwise,
	 * executing "rmmod" command is unable to make TIPC module deleted
	 * after TIPC module is inserted successfully.
	 *
	 * However, the reference count is ever increased twice in
	 * sock_create_kern(): one is to increase the reference count of owner
	 * of TIPC socket's proto_ops struct; another is to increment the
	 * reference count of owner of TIPC proto struct. Therefore, we must
	 * decrement the module reference count twice to ensure that it keeps
	 * zero after server's listening socket is created. Of course, we
	 * must bump the module reference count twice as well before the socket
	 * is closed.
	 */
	module_put(lsock->ops->owner);
	module_put(sk->sk_prot_creator->owner);

	return 0;
err:
	sock_release(lsock);
	return -EINVAL;
}

bool tipc_topsrv_kern_subscr(struct net *net, u32 port, u32 type, u32 lower,
			     u32 upper, u32 filter, int *conid)
{
	struct tipc_subscr sub;
	struct tipc_conn *con;
	int rc;

	sub.seq.type = type;
	sub.seq.lower = lower;
	sub.seq.upper = upper;
	sub.timeout = TIPC_WAIT_FOREVER;
	sub.filter = filter;
	*(u32 *)&sub.usr_handle = port;

	con = tipc_conn_alloc(tipc_topsrv(net));
	if (IS_ERR(con))
		return false;

	*conid = con->conid;
	con->sock = NULL;
	rc = tipc_conn_rcv_sub(tipc_topsrv(net), con, &sub);
	if (rc >= 0)
		return true;
	conn_put(con);
	return false;
}

void tipc_topsrv_kern_unsubscr(struct net *net, int conid)
{
	struct tipc_conn *con;

	con = tipc_conn_lookup(tipc_topsrv(net), conid);
	if (!con)
		return;

	test_and_clear_bit(CF_CONNECTED, &con->flags);
	tipc_conn_delete_sub(con, NULL);
	conn_put(con);
	conn_put(con);
}

static void tipc_topsrv_kern_evt(struct net *net, struct tipc_event *evt)
{
	u32 port = *(u32 *)&evt->s.usr_handle;
	u32 self = tipc_own_addr(net);
	struct sk_buff_head evtq;
	struct sk_buff *skb;

	skb = tipc_msg_create(TOP_SRV, 0, INT_H_SIZE, sizeof(*evt),
			      self, self, port, port, 0);
	if (!skb)
		return;
	msg_set_dest_droppable(buf_msg(skb), true);
	memcpy(msg_data(buf_msg(skb)), evt, sizeof(*evt));
	skb_queue_head_init(&evtq);
	__skb_queue_tail(&evtq, skb);
	tipc_loopback_trace(net, &evtq);
	tipc_sk_rcv(net, &evtq);
}

static int tipc_topsrv_work_start(struct tipc_topsrv *s)
{
	s->rcv_wq = alloc_ordered_workqueue("tipc_rcv", 0);
	if (!s->rcv_wq) {
		pr_err("can't start tipc receive workqueue\n");
		return -ENOMEM;
	}

	s->send_wq = alloc_ordered_workqueue("tipc_send", 0);
	if (!s->send_wq) {
		pr_err("can't start tipc send workqueue\n");
		destroy_workqueue(s->rcv_wq);
		return -ENOMEM;
	}

	return 0;
}

static void tipc_topsrv_work_stop(struct tipc_topsrv *s)
{
	destroy_workqueue(s->rcv_wq);
	destroy_workqueue(s->send_wq);
}

static int tipc_topsrv_start(struct net *net)
{
	struct tipc_net *tn = tipc_net(net);
	const char name[] = "topology_server";
	struct tipc_topsrv *srv;
	int ret;

	srv = kzalloc(sizeof(*srv), GFP_ATOMIC);
	if (!srv)
		return -ENOMEM;

	srv->net = net;
	INIT_WORK(&srv->awork, tipc_topsrv_accept);

	strscpy(srv->name, name, sizeof(srv->name));
	tn->topsrv = srv;
	atomic_set(&tn->subscription_count, 0);

	spin_lock_init(&srv->idr_lock);
	idr_init(&srv->conn_idr);
	srv->idr_in_use = 0;

	ret = tipc_topsrv_work_start(srv);
	if (ret < 0)
		return ret;

	ret = tipc_topsrv_create_listener(srv);
	if (ret < 0)
		tipc_topsrv_work_stop(srv);

	return ret;
}

static void tipc_topsrv_stop(struct net *net)
{
	struct tipc_topsrv *srv = tipc_topsrv(net);
	struct socket *lsock = srv->listener;
	struct tipc_conn *con;
	int id;

	spin_lock_bh(&srv->idr_lock);
	for (id = 0; srv->idr_in_use; id++) {
		con = idr_find(&srv->conn_idr, id);
		if (con) {
			spin_unlock_bh(&srv->idr_lock);
			tipc_conn_close(con);
			spin_lock_bh(&srv->idr_lock);
		}
	}
	__module_get(lsock->ops->owner);
	__module_get(lsock->sk->sk_prot_creator->owner);
	srv->listener = NULL;
	spin_unlock_bh(&srv->idr_lock);
	sock_release(lsock);
	tipc_topsrv_work_stop(srv);
	idr_destroy(&srv->conn_idr);
	kfree(srv);
}

int __net_init tipc_topsrv_init_net(struct net *net)
{
	return tipc_topsrv_start(net);
}

void __net_exit tipc_topsrv_exit_net(struct net *net)
{
	tipc_topsrv_stop(net);
}