summaryrefslogtreecommitdiffstats
path: root/net/rxrpc/ar-connection.c
blob: 6c71ed1caf16727a587c90ff81dcd6a7abd3d10b (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
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
/* RxRPC virtual connection handler
 *
 * Copyright (C) 2007 Red Hat, Inc. All Rights Reserved.
 * Written by David Howells (dhowells@redhat.com)
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version
 * 2 of the License, or (at your option) any later version.
 */

#include <linux/module.h>
#include <linux/slab.h>
#include <linux/net.h>
#include <linux/skbuff.h>
#include <linux/crypto.h>
#include <net/sock.h>
#include <net/af_rxrpc.h>
#include "ar-internal.h"

/*
 * Time till a connection expires after last use (in seconds).
 */
unsigned rxrpc_connection_expiry = 10 * 60;

static void rxrpc_connection_reaper(struct work_struct *work);

LIST_HEAD(rxrpc_connections);
DEFINE_RWLOCK(rxrpc_connection_lock);
static DECLARE_DELAYED_WORK(rxrpc_connection_reap, rxrpc_connection_reaper);

/*
 * allocate a new client connection bundle
 */
static struct rxrpc_conn_bundle *rxrpc_alloc_bundle(gfp_t gfp)
{
	struct rxrpc_conn_bundle *bundle;

	_enter("");

	bundle = kzalloc(sizeof(struct rxrpc_conn_bundle), gfp);
	if (bundle) {
		INIT_LIST_HEAD(&bundle->unused_conns);
		INIT_LIST_HEAD(&bundle->avail_conns);
		INIT_LIST_HEAD(&bundle->busy_conns);
		init_waitqueue_head(&bundle->chanwait);
		atomic_set(&bundle->usage, 1);
	}

	_leave(" = %p", bundle);
	return bundle;
}

/*
 * compare bundle parameters with what we're looking for
 * - return -ve, 0 or +ve
 */
static inline
int rxrpc_cmp_bundle(const struct rxrpc_conn_bundle *bundle,
		     struct key *key, __be16 service_id)
{
	return (bundle->service_id - service_id) ?:
		((unsigned long) bundle->key - (unsigned long) key);
}

/*
 * get bundle of client connections that a client socket can make use of
 */
struct rxrpc_conn_bundle *rxrpc_get_bundle(struct rxrpc_sock *rx,
					   struct rxrpc_transport *trans,
					   struct key *key,
					   __be16 service_id,
					   gfp_t gfp)
{
	struct rxrpc_conn_bundle *bundle, *candidate;
	struct rb_node *p, *parent, **pp;

	_enter("%p{%x},%x,%hx,",
	       rx, key_serial(key), trans->debug_id, ntohs(service_id));

	if (rx->trans == trans && rx->bundle) {
		atomic_inc(&rx->bundle->usage);
		return rx->bundle;
	}

	/* search the extant bundles first for one that matches the specified
	 * user ID */
	spin_lock(&trans->client_lock);

	p = trans->bundles.rb_node;
	while (p) {
		bundle = rb_entry(p, struct rxrpc_conn_bundle, node);

		if (rxrpc_cmp_bundle(bundle, key, service_id) < 0)
			p = p->rb_left;
		else if (rxrpc_cmp_bundle(bundle, key, service_id) > 0)
			p = p->rb_right;
		else
			goto found_extant_bundle;
	}

	spin_unlock(&trans->client_lock);

	/* not yet present - create a candidate for a new record and then
	 * redo the search */
	candidate = rxrpc_alloc_bundle(gfp);
	if (!candidate) {
		_leave(" = -ENOMEM");
		return ERR_PTR(-ENOMEM);
	}

	candidate->key = key_get(key);
	candidate->service_id = service_id;

	spin_lock(&trans->client_lock);

	pp = &trans->bundles.rb_node;
	parent = NULL;
	while (*pp) {
		parent = *pp;
		bundle = rb_entry(parent, struct rxrpc_conn_bundle, node);

		if (rxrpc_cmp_bundle(bundle, key, service_id) < 0)
			pp = &(*pp)->rb_left;
		else if (rxrpc_cmp_bundle(bundle, key, service_id) > 0)
			pp = &(*pp)->rb_right;
		else
			goto found_extant_second;
	}

	/* second search also failed; add the new bundle */
	bundle = candidate;
	candidate = NULL;

	rb_link_node(&bundle->node, parent, pp);
	rb_insert_color(&bundle->node, &trans->bundles);
	spin_unlock(&trans->client_lock);
	_net("BUNDLE new on trans %d", trans->debug_id);
	if (!rx->bundle && rx->sk.sk_state == RXRPC_CLIENT_CONNECTED) {
		atomic_inc(&bundle->usage);
		rx->bundle = bundle;
	}
	_leave(" = %p [new]", bundle);
	return bundle;

	/* we found the bundle in the list immediately */
found_extant_bundle:
	atomic_inc(&bundle->usage);
	spin_unlock(&trans->client_lock);
	_net("BUNDLE old on trans %d", trans->debug_id);
	if (!rx->bundle && rx->sk.sk_state == RXRPC_CLIENT_CONNECTED) {
		atomic_inc(&bundle->usage);
		rx->bundle = bundle;
	}
	_leave(" = %p [extant %d]", bundle, atomic_read(&bundle->usage));
	return bundle;

	/* we found the bundle on the second time through the list */
found_extant_second:
	atomic_inc(&bundle->usage);
	spin_unlock(&trans->client_lock);
	kfree(candidate);
	_net("BUNDLE old2 on trans %d", trans->debug_id);
	if (!rx->bundle && rx->sk.sk_state == RXRPC_CLIENT_CONNECTED) {
		atomic_inc(&bundle->usage);
		rx->bundle = bundle;
	}
	_leave(" = %p [second %d]", bundle, atomic_read(&bundle->usage));
	return bundle;
}

/*
 * release a bundle
 */
void rxrpc_put_bundle(struct rxrpc_transport *trans,
		      struct rxrpc_conn_bundle *bundle)
{
	_enter("%p,%p{%d}",trans, bundle, atomic_read(&bundle->usage));

	if (atomic_dec_and_lock(&bundle->usage, &trans->client_lock)) {
		_debug("Destroy bundle");
		rb_erase(&bundle->node, &trans->bundles);
		spin_unlock(&trans->client_lock);
		ASSERT(list_empty(&bundle->unused_conns));
		ASSERT(list_empty(&bundle->avail_conns));
		ASSERT(list_empty(&bundle->busy_conns));
		ASSERTCMP(bundle->num_conns, ==, 0);
		key_put(bundle->key);
		kfree(bundle);
	}

	_leave("");
}

/*
 * allocate a new connection
 */
static struct rxrpc_connection *rxrpc_alloc_connection(gfp_t gfp)
{
	struct rxrpc_connection *conn;

	_enter("");

	conn = kzalloc(sizeof(struct rxrpc_connection), gfp);
	if (conn) {
		INIT_WORK(&conn->processor, &rxrpc_process_connection);
		INIT_LIST_HEAD(&conn->bundle_link);
		conn->calls = RB_ROOT;
		skb_queue_head_init(&conn->rx_queue);
		rwlock_init(&conn->lock);
		spin_lock_init(&conn->state_lock);
		atomic_set(&conn->usage, 1);
		conn->debug_id = atomic_inc_return(&rxrpc_debug_id);
		conn->avail_calls = RXRPC_MAXCALLS;
		conn->size_align = 4;
		conn->header_size = sizeof(struct rxrpc_header);
	}

	_leave(" = %p{%d}", conn, conn ? conn->debug_id : 0);
	return conn;
}

/*
 * assign a connection ID to a connection and add it to the transport's
 * connection lookup tree
 * - called with transport client lock held
 */
static void rxrpc_assign_connection_id(struct rxrpc_connection *conn)
{
	struct rxrpc_connection *xconn;
	struct rb_node *parent, **p;
	__be32 epoch;
	u32 real_conn_id;

	_enter("");

	epoch = conn->epoch;

	write_lock_bh(&conn->trans->conn_lock);

	conn->trans->conn_idcounter += RXRPC_CID_INC;
	if (conn->trans->conn_idcounter < RXRPC_CID_INC)
		conn->trans->conn_idcounter = RXRPC_CID_INC;
	real_conn_id = conn->trans->conn_idcounter;

attempt_insertion:
	parent = NULL;
	p = &conn->trans->client_conns.rb_node;

	while (*p) {
		parent = *p;
		xconn = rb_entry(parent, struct rxrpc_connection, node);

		if (epoch < xconn->epoch)
			p = &(*p)->rb_left;
		else if (epoch > xconn->epoch)
			p = &(*p)->rb_right;
		else if (real_conn_id < xconn->real_conn_id)
			p = &(*p)->rb_left;
		else if (real_conn_id > xconn->real_conn_id)
			p = &(*p)->rb_right;
		else
			goto id_exists;
	}

	/* we've found a suitable hole - arrange for this connection to occupy
	 * it */
	rb_link_node(&conn->node, parent, p);
	rb_insert_color(&conn->node, &conn->trans->client_conns);

	conn->real_conn_id = real_conn_id;
	conn->cid = htonl(real_conn_id);
	write_unlock_bh(&conn->trans->conn_lock);
	_leave(" [CONNID %x CID %x]", real_conn_id, ntohl(conn->cid));
	return;

	/* we found a connection with the proposed ID - walk the tree from that
	 * point looking for the next unused ID */
id_exists:
	for (;;) {
		real_conn_id += RXRPC_CID_INC;
		if (real_conn_id < RXRPC_CID_INC) {
			real_conn_id = RXRPC_CID_INC;
			conn->trans->conn_idcounter = real_conn_id;
			goto attempt_insertion;
		}

		parent = rb_next(parent);
		if (!parent)
			goto attempt_insertion;

		xconn = rb_entry(parent, struct rxrpc_connection, node);
		if (epoch < xconn->epoch ||
		    real_conn_id < xconn->real_conn_id)
			goto attempt_insertion;
	}
}

/*
 * add a call to a connection's call-by-ID tree
 */
static void rxrpc_add_call_ID_to_conn(struct rxrpc_connection *conn,
				      struct rxrpc_call *call)
{
	struct rxrpc_call *xcall;
	struct rb_node *parent, **p;
	__be32 call_id;

	write_lock_bh(&conn->lock);

	call_id = call->call_id;
	p = &conn->calls.rb_node;
	parent = NULL;
	while (*p) {
		parent = *p;
		xcall = rb_entry(parent, struct rxrpc_call, conn_node);

		if (call_id < xcall->call_id)
			p = &(*p)->rb_left;
		else if (call_id > xcall->call_id)
			p = &(*p)->rb_right;
		else
			BUG();
	}

	rb_link_node(&call->conn_node, parent, p);
	rb_insert_color(&call->conn_node, &conn->calls);

	write_unlock_bh(&conn->lock);
}

/*
 * connect a call on an exclusive connection
 */
static int rxrpc_connect_exclusive(struct rxrpc_sock *rx,
				   struct rxrpc_transport *trans,
				   __be16 service_id,
				   struct rxrpc_call *call,
				   gfp_t gfp)
{
	struct rxrpc_connection *conn;
	int chan, ret;

	_enter("");

	conn = rx->conn;
	if (!conn) {
		/* not yet present - create a candidate for a new connection
		 * and then redo the check */
		conn = rxrpc_alloc_connection(gfp);
		if (!conn) {
			_leave(" = -ENOMEM");
			return -ENOMEM;
		}

		conn->trans = trans;
		conn->bundle = NULL;
		conn->service_id = service_id;
		conn->epoch = rxrpc_epoch;
		conn->in_clientflag = 0;
		conn->out_clientflag = RXRPC_CLIENT_INITIATED;
		conn->cid = 0;
		conn->state = RXRPC_CONN_CLIENT;
		conn->avail_calls = RXRPC_MAXCALLS - 1;
		conn->security_level = rx->min_sec_level;
		conn->key = key_get(rx->key);

		ret = rxrpc_init_client_conn_security(conn);
		if (ret < 0) {
			key_put(conn->key);
			kfree(conn);
			_leave(" = %d [key]", ret);
			return ret;
		}

		write_lock_bh(&rxrpc_connection_lock);
		list_add_tail(&conn->link, &rxrpc_connections);
		write_unlock_bh(&rxrpc_connection_lock);

		spin_lock(&trans->client_lock);
		atomic_inc(&trans->usage);

		_net("CONNECT EXCL new %d on TRANS %d",
		     conn->debug_id, conn->trans->debug_id);

		rxrpc_assign_connection_id(conn);
		rx->conn = conn;
	} else {
		spin_lock(&trans->client_lock);
	}

	/* we've got a connection with a free channel and we can now attach the
	 * call to it
	 * - we're holding the transport's client lock
	 * - we're holding a reference on the connection
	 */
	for (chan = 0; chan < RXRPC_MAXCALLS; chan++)
		if (!conn->channels[chan])
			goto found_channel;
	goto no_free_channels;

found_channel:
	atomic_inc(&conn->usage);
	conn->channels[chan] = call;
	call->conn = conn;
	call->channel = chan;
	call->cid = conn->cid | htonl(chan);
	call->call_id = htonl(++conn->call_counter);

	_net("CONNECT client on conn %d chan %d as call %x",
	     conn->debug_id, chan, ntohl(call->call_id));

	spin_unlock(&trans->client_lock);

	rxrpc_add_call_ID_to_conn(conn, call);
	_leave(" = 0");
	return 0;

no_free_channels:
	spin_unlock(&trans->client_lock);
	_leave(" = -ENOSR");
	return -ENOSR;
}

/*
 * find a connection for a call
 * - called in process context with IRQs enabled
 */
int rxrpc_connect_call(struct rxrpc_sock *rx,
		       struct rxrpc_transport *trans,
		       struct rxrpc_conn_bundle *bundle,
		       struct rxrpc_call *call,
		       gfp_t gfp)
{
	struct rxrpc_connection *conn, *candidate;
	int chan, ret;

	DECLARE_WAITQUEUE(myself, current);

	_enter("%p,%lx,", rx, call->user_call_ID);

	if (test_bit(RXRPC_SOCK_EXCLUSIVE_CONN, &rx->flags))
		return rxrpc_connect_exclusive(rx, trans, bundle->service_id,
					       call, gfp);

	spin_lock(&trans->client_lock);
	for (;;) {
		/* see if the bundle has a call slot available */
		if (!list_empty(&bundle->avail_conns)) {
			_debug("avail");
			conn = list_entry(bundle->avail_conns.next,
					  struct rxrpc_connection,
					  bundle_link);
			if (conn->state >= RXRPC_CONN_REMOTELY_ABORTED) {
				list_del_init(&conn->bundle_link);
				bundle->num_conns--;
				continue;
			}
			if (--conn->avail_calls == 0)
				list_move(&conn->bundle_link,
					  &bundle->busy_conns);
			ASSERTCMP(conn->avail_calls, <, RXRPC_MAXCALLS);
			ASSERT(conn->channels[0] == NULL ||
			       conn->channels[1] == NULL ||
			       conn->channels[2] == NULL ||
			       conn->channels[3] == NULL);
			atomic_inc(&conn->usage);
			break;
		}

		if (!list_empty(&bundle->unused_conns)) {
			_debug("unused");
			conn = list_entry(bundle->unused_conns.next,
					  struct rxrpc_connection,
					  bundle_link);
			if (conn->state >= RXRPC_CONN_REMOTELY_ABORTED) {
				list_del_init(&conn->bundle_link);
				bundle->num_conns--;
				continue;
			}
			ASSERTCMP(conn->avail_calls, ==, RXRPC_MAXCALLS);
			conn->avail_calls = RXRPC_MAXCALLS - 1;
			ASSERT(conn->channels[0] == NULL &&
			       conn->channels[1] == NULL &&
			       conn->channels[2] == NULL &&
			       conn->channels[3] == NULL);
			atomic_inc(&conn->usage);
			list_move(&conn->bundle_link, &bundle->avail_conns);
			break;
		}

		/* need to allocate a new connection */
		_debug("get new conn [%d]", bundle->num_conns);

		spin_unlock(&trans->client_lock);

		if (signal_pending(current))
			goto interrupted;

		if (bundle->num_conns >= 20) {
			_debug("too many conns");

			if (!gfpflags_allow_blocking(gfp)) {
				_leave(" = -EAGAIN");
				return -EAGAIN;
			}

			add_wait_queue(&bundle->chanwait, &myself);
			for (;;) {
				set_current_state(TASK_INTERRUPTIBLE);
				if (bundle->num_conns < 20 ||
				    !list_empty(&bundle->unused_conns) ||
				    !list_empty(&bundle->avail_conns))
					break;
				if (signal_pending(current))
					goto interrupted_dequeue;
				schedule();
			}
			remove_wait_queue(&bundle->chanwait, &myself);
			__set_current_state(TASK_RUNNING);
			spin_lock(&trans->client_lock);
			continue;
		}

		/* not yet present - create a candidate for a new connection and then
		 * redo the check */
		candidate = rxrpc_alloc_connection(gfp);
		if (!candidate) {
			_leave(" = -ENOMEM");
			return -ENOMEM;
		}

		candidate->trans = trans;
		candidate->bundle = bundle;
		candidate->service_id = bundle->service_id;
		candidate->epoch = rxrpc_epoch;
		candidate->in_clientflag = 0;
		candidate->out_clientflag = RXRPC_CLIENT_INITIATED;
		candidate->cid = 0;
		candidate->state = RXRPC_CONN_CLIENT;
		candidate->avail_calls = RXRPC_MAXCALLS;
		candidate->security_level = rx->min_sec_level;
		candidate->key = key_get(bundle->key);

		ret = rxrpc_init_client_conn_security(candidate);
		if (ret < 0) {
			key_put(candidate->key);
			kfree(candidate);
			_leave(" = %d [key]", ret);
			return ret;
		}

		write_lock_bh(&rxrpc_connection_lock);
		list_add_tail(&candidate->link, &rxrpc_connections);
		write_unlock_bh(&rxrpc_connection_lock);

		spin_lock(&trans->client_lock);

		list_add(&candidate->bundle_link, &bundle->unused_conns);
		bundle->num_conns++;
		atomic_inc(&bundle->usage);
		atomic_inc(&trans->usage);

		_net("CONNECT new %d on TRANS %d",
		     candidate->debug_id, candidate->trans->debug_id);

		rxrpc_assign_connection_id(candidate);
		if (candidate->security)
			candidate->security->prime_packet_security(candidate);

		/* leave the candidate lurking in zombie mode attached to the
		 * bundle until we're ready for it */
		rxrpc_put_connection(candidate);
		candidate = NULL;
	}

	/* we've got a connection with a free channel and we can now attach the
	 * call to it
	 * - we're holding the transport's client lock
	 * - we're holding a reference on the connection
	 * - we're holding a reference on the bundle
	 */
	for (chan = 0; chan < RXRPC_MAXCALLS; chan++)
		if (!conn->channels[chan])
			goto found_channel;
	ASSERT(conn->channels[0] == NULL ||
	       conn->channels[1] == NULL ||
	       conn->channels[2] == NULL ||
	       conn->channels[3] == NULL);
	BUG();

found_channel:
	conn->channels[chan] = call;
	call->conn = conn;
	call->channel = chan;
	call->cid = conn->cid | htonl(chan);
	call->call_id = htonl(++conn->call_counter);

	_net("CONNECT client on conn %d chan %d as call %x",
	     conn->debug_id, chan, ntohl(call->call_id));

	ASSERTCMP(conn->avail_calls, <, RXRPC_MAXCALLS);
	spin_unlock(&trans->client_lock);

	rxrpc_add_call_ID_to_conn(conn, call);

	_leave(" = 0");
	return 0;

interrupted_dequeue:
	remove_wait_queue(&bundle->chanwait, &myself);
	__set_current_state(TASK_RUNNING);
interrupted:
	_leave(" = -ERESTARTSYS");
	return -ERESTARTSYS;
}

/*
 * get a record of an incoming connection
 */
struct rxrpc_connection *
rxrpc_incoming_connection(struct rxrpc_transport *trans,
			  struct rxrpc_header *hdr,
			  gfp_t gfp)
{
	struct rxrpc_connection *conn, *candidate = NULL;
	struct rb_node *p, **pp;
	const char *new = "old";
	__be32 epoch;
	u32 conn_id;

	_enter("");

	ASSERT(hdr->flags & RXRPC_CLIENT_INITIATED);

	epoch = hdr->epoch;
	conn_id = ntohl(hdr->cid) & RXRPC_CIDMASK;

	/* search the connection list first */
	read_lock_bh(&trans->conn_lock);

	p = trans->server_conns.rb_node;
	while (p) {
		conn = rb_entry(p, struct rxrpc_connection, node);

		_debug("maybe %x", conn->real_conn_id);

		if (epoch < conn->epoch)
			p = p->rb_left;
		else if (epoch > conn->epoch)
			p = p->rb_right;
		else if (conn_id < conn->real_conn_id)
			p = p->rb_left;
		else if (conn_id > conn->real_conn_id)
			p = p->rb_right;
		else
			goto found_extant_connection;
	}
	read_unlock_bh(&trans->conn_lock);

	/* not yet present - create a candidate for a new record and then
	 * redo the search */
	candidate = rxrpc_alloc_connection(gfp);
	if (!candidate) {
		_leave(" = -ENOMEM");
		return ERR_PTR(-ENOMEM);
	}

	candidate->trans = trans;
	candidate->epoch = hdr->epoch;
	candidate->cid = hdr->cid & cpu_to_be32(RXRPC_CIDMASK);
	candidate->service_id = hdr->serviceId;
	candidate->security_ix = hdr->securityIndex;
	candidate->in_clientflag = RXRPC_CLIENT_INITIATED;
	candidate->out_clientflag = 0;
	candidate->real_conn_id = conn_id;
	candidate->state = RXRPC_CONN_SERVER;
	if (candidate->service_id)
		candidate->state = RXRPC_CONN_SERVER_UNSECURED;

	write_lock_bh(&trans->conn_lock);

	pp = &trans->server_conns.rb_node;
	p = NULL;
	while (*pp) {
		p = *pp;
		conn = rb_entry(p, struct rxrpc_connection, node);

		if (epoch < conn->epoch)
			pp = &(*pp)->rb_left;
		else if (epoch > conn->epoch)
			pp = &(*pp)->rb_right;
		else if (conn_id < conn->real_conn_id)
			pp = &(*pp)->rb_left;
		else if (conn_id > conn->real_conn_id)
			pp = &(*pp)->rb_right;
		else
			goto found_extant_second;
	}

	/* we can now add the new candidate to the list */
	conn = candidate;
	candidate = NULL;
	rb_link_node(&conn->node, p, pp);
	rb_insert_color(&conn->node, &trans->server_conns);
	atomic_inc(&conn->trans->usage);

	write_unlock_bh(&trans->conn_lock);

	write_lock_bh(&rxrpc_connection_lock);
	list_add_tail(&conn->link, &rxrpc_connections);
	write_unlock_bh(&rxrpc_connection_lock);

	new = "new";

success:
	_net("CONNECTION %s %d {%x}", new, conn->debug_id, conn->real_conn_id);

	_leave(" = %p {u=%d}", conn, atomic_read(&conn->usage));
	return conn;

	/* we found the connection in the list immediately */
found_extant_connection:
	if (hdr->securityIndex != conn->security_ix) {
		read_unlock_bh(&trans->conn_lock);
		goto security_mismatch;
	}
	atomic_inc(&conn->usage);
	read_unlock_bh(&trans->conn_lock);
	goto success;

	/* we found the connection on the second time through the list */
found_extant_second:
	if (hdr->securityIndex != conn->security_ix) {
		write_unlock_bh(&trans->conn_lock);
		goto security_mismatch;
	}
	atomic_inc(&conn->usage);
	write_unlock_bh(&trans->conn_lock);
	kfree(candidate);
	goto success;

security_mismatch:
	kfree(candidate);
	_leave(" = -EKEYREJECTED");
	return ERR_PTR(-EKEYREJECTED);
}

/*
 * find a connection based on transport and RxRPC connection ID for an incoming
 * packet
 */
struct rxrpc_connection *rxrpc_find_connection(struct rxrpc_transport *trans,
					       struct rxrpc_header *hdr)
{
	struct rxrpc_connection *conn;
	struct rb_node *p;
	__be32 epoch;
	u32 conn_id;

	_enter(",{%x,%x}", ntohl(hdr->cid), hdr->flags);

	read_lock_bh(&trans->conn_lock);

	conn_id = ntohl(hdr->cid) & RXRPC_CIDMASK;
	epoch = hdr->epoch;

	if (hdr->flags & RXRPC_CLIENT_INITIATED)
		p = trans->server_conns.rb_node;
	else
		p = trans->client_conns.rb_node;

	while (p) {
		conn = rb_entry(p, struct rxrpc_connection, node);

		_debug("maybe %x", conn->real_conn_id);

		if (epoch < conn->epoch)
			p = p->rb_left;
		else if (epoch > conn->epoch)
			p = p->rb_right;
		else if (conn_id < conn->real_conn_id)
			p = p->rb_left;
		else if (conn_id > conn->real_conn_id)
			p = p->rb_right;
		else
			goto found;
	}

	read_unlock_bh(&trans->conn_lock);
	_leave(" = NULL");
	return NULL;

found:
	atomic_inc(&conn->usage);
	read_unlock_bh(&trans->conn_lock);
	_leave(" = %p", conn);
	return conn;
}

/*
 * release a virtual connection
 */
void rxrpc_put_connection(struct rxrpc_connection *conn)
{
	_enter("%p{u=%d,d=%d}",
	       conn, atomic_read(&conn->usage), conn->debug_id);

	ASSERTCMP(atomic_read(&conn->usage), >, 0);

	conn->put_time = ktime_get_seconds();
	if (atomic_dec_and_test(&conn->usage)) {
		_debug("zombie");
		rxrpc_queue_delayed_work(&rxrpc_connection_reap, 0);
	}

	_leave("");
}

/*
 * destroy a virtual connection
 */
static void rxrpc_destroy_connection(struct rxrpc_connection *conn)
{
	_enter("%p{%d}", conn, atomic_read(&conn->usage));

	ASSERTCMP(atomic_read(&conn->usage), ==, 0);

	_net("DESTROY CONN %d", conn->debug_id);

	if (conn->bundle)
		rxrpc_put_bundle(conn->trans, conn->bundle);

	ASSERT(RB_EMPTY_ROOT(&conn->calls));
	rxrpc_purge_queue(&conn->rx_queue);

	rxrpc_clear_conn_security(conn);
	rxrpc_put_transport(conn->trans);
	kfree(conn);
	_leave("");
}

/*
 * reap dead connections
 */
static void rxrpc_connection_reaper(struct work_struct *work)
{
	struct rxrpc_connection *conn, *_p;
	unsigned long now, earliest, reap_time;

	LIST_HEAD(graveyard);

	_enter("");

	now = ktime_get_seconds();
	earliest = ULONG_MAX;

	write_lock_bh(&rxrpc_connection_lock);
	list_for_each_entry_safe(conn, _p, &rxrpc_connections, link) {
		_debug("reap CONN %d { u=%d,t=%ld }",
		       conn->debug_id, atomic_read(&conn->usage),
		       (long) now - (long) conn->put_time);

		if (likely(atomic_read(&conn->usage) > 0))
			continue;

		spin_lock(&conn->trans->client_lock);
		write_lock(&conn->trans->conn_lock);
		reap_time = conn->put_time + rxrpc_connection_expiry;

		if (atomic_read(&conn->usage) > 0) {
			;
		} else if (reap_time <= now) {
			list_move_tail(&conn->link, &graveyard);
			if (conn->out_clientflag)
				rb_erase(&conn->node,
					 &conn->trans->client_conns);
			else
				rb_erase(&conn->node,
					 &conn->trans->server_conns);
			if (conn->bundle) {
				list_del_init(&conn->bundle_link);
				conn->bundle->num_conns--;
			}

		} else if (reap_time < earliest) {
			earliest = reap_time;
		}

		write_unlock(&conn->trans->conn_lock);
		spin_unlock(&conn->trans->client_lock);
	}
	write_unlock_bh(&rxrpc_connection_lock);

	if (earliest != ULONG_MAX) {
		_debug("reschedule reaper %ld", (long) earliest - now);
		ASSERTCMP(earliest, >, now);
		rxrpc_queue_delayed_work(&rxrpc_connection_reap,
					 (earliest - now) * HZ);
	}

	/* then destroy all those pulled out */
	while (!list_empty(&graveyard)) {
		conn = list_entry(graveyard.next, struct rxrpc_connection,
				  link);
		list_del_init(&conn->link);

		ASSERTCMP(atomic_read(&conn->usage), ==, 0);
		rxrpc_destroy_connection(conn);
	}

	_leave("");
}

/*
 * preemptively destroy all the connection records rather than waiting for them
 * to time out
 */
void __exit rxrpc_destroy_all_connections(void)
{
	_enter("");

	rxrpc_connection_expiry = 0;
	cancel_delayed_work(&rxrpc_connection_reap);
	rxrpc_queue_delayed_work(&rxrpc_connection_reap, 0);

	_leave("");
}