aboutsummaryrefslogtreecommitdiff
path: root/net/llc/llc_conn.c
blob: 8ebc2769dfdabc88c288468002148d5c974fd68f (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
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
/*
 * llc_conn.c - Driver routines for connection component.
 *
 * Copyright (c) 1997 by Procom Technology, Inc.
 *		 2001-2003 by Arnaldo Carvalho de Melo <acme@conectiva.com.br>
 *
 * This program can be redistributed or modified under the terms of the
 * GNU General Public License as published by the Free Software Foundation.
 * This program is distributed without any warranty or implied warranty
 * of merchantability or fitness for a particular purpose.
 *
 * See the GNU General Public License for more details.
 */

#include <linux/init.h>
#include <net/llc_sap.h>
#include <net/llc_conn.h>
#include <net/sock.h>
#include <net/tcp_states.h>
#include <net/llc_c_ev.h>
#include <net/llc_c_ac.h>
#include <net/llc_c_st.h>
#include <net/llc_pdu.h>

#if 0
#define dprintk(args...) printk(KERN_DEBUG args)
#else
#define dprintk(args...)
#endif

static int llc_find_offset(int state, int ev_type);
static void llc_conn_send_pdus(struct sock *sk);
static int llc_conn_service(struct sock *sk, struct sk_buff *skb);
static int llc_exec_conn_trans_actions(struct sock *sk,
				       struct llc_conn_state_trans *trans,
				       struct sk_buff *ev);
static struct llc_conn_state_trans *llc_qualify_conn_ev(struct sock *sk,
							struct sk_buff *skb);

/* Offset table on connection states transition diagram */
static int llc_offset_table[NBR_CONN_STATES][NBR_CONN_EV];

int sysctl_llc2_ack_timeout = LLC2_ACK_TIME * HZ;
int sysctl_llc2_p_timeout = LLC2_P_TIME * HZ;
int sysctl_llc2_rej_timeout = LLC2_REJ_TIME * HZ;
int sysctl_llc2_busy_timeout = LLC2_BUSY_TIME * HZ;

/**
 *	llc_conn_state_process - sends event to connection state machine
 *	@sk: connection
 *	@skb: occurred event
 *
 *	Sends an event to connection state machine. After processing event
 *	(executing it's actions and changing state), upper layer will be
 *	indicated or confirmed, if needed. Returns 0 for success, 1 for
 *	failure. The socket lock has to be held before calling this function.
 */
int llc_conn_state_process(struct sock *sk, struct sk_buff *skb)
{
	int rc;
	struct llc_sock *llc = llc_sk(skb->sk);
	struct llc_conn_state_ev *ev = llc_conn_ev(skb);

	/*
	 * We have to hold the skb, because llc_conn_service will kfree it in
	 * the sending path and we need to look at the skb->cb, where we encode
	 * llc_conn_state_ev.
	 */
	skb_get(skb);
	ev->ind_prim = ev->cfm_prim = 0;
	/*
	 * Send event to state machine
	 */
	rc = llc_conn_service(skb->sk, skb);
	if (unlikely(rc != 0)) {
		printk(KERN_ERR "%s: llc_conn_service failed\n", __FUNCTION__);
		goto out_kfree_skb;
	}

	if (unlikely(!ev->ind_prim && !ev->cfm_prim)) {
		/* indicate or confirm not required */
		/* XXX this is not very pretty, perhaps we should store
		 * XXX indicate/confirm-needed state in the llc_conn_state_ev
		 * XXX control block of the SKB instead? -DaveM
		 */
		if (!skb->next)
			goto out_kfree_skb;
		goto out_skb_put;
	}

	if (unlikely(ev->ind_prim && ev->cfm_prim)) /* Paranoia */
		skb_get(skb);

	switch (ev->ind_prim) {
	case LLC_DATA_PRIM:
		llc_save_primitive(sk, skb, LLC_DATA_PRIM);
		if (unlikely(sock_queue_rcv_skb(sk, skb))) {
			/*
			 * shouldn't happen
			 */
			printk(KERN_ERR "%s: sock_queue_rcv_skb failed!\n",
			       __FUNCTION__);
			kfree_skb(skb);
		}
		break;
	case LLC_CONN_PRIM:
		/*
		 * Can't be sock_queue_rcv_skb, because we have to leave the
		 * skb->sk pointing to the newly created struct sock in
		 * llc_conn_handler. -acme
		 */
		skb_queue_tail(&sk->sk_receive_queue, skb);
		sk->sk_state_change(sk);
		break;
	case LLC_DISC_PRIM:
		sock_hold(sk);
		if (sk->sk_type == SOCK_STREAM &&
		    sk->sk_state == TCP_ESTABLISHED) {
			sk->sk_shutdown       = SHUTDOWN_MASK;
			sk->sk_socket->state  = SS_UNCONNECTED;
			sk->sk_state          = TCP_CLOSE;
			if (!sock_flag(sk, SOCK_DEAD)) {
				sock_set_flag(sk, SOCK_DEAD);
				sk->sk_state_change(sk);
			}
		}
		kfree_skb(skb);
		sock_put(sk);
		break;
	case LLC_RESET_PRIM:
		/*
		 * FIXME:
		 * RESET is not being notified to upper layers for now
		 */
		printk(KERN_INFO "%s: received a reset ind!\n", __FUNCTION__);
		kfree_skb(skb);
		break;
	default:
		if (ev->ind_prim) {
			printk(KERN_INFO "%s: received unknown %d prim!\n",
				__FUNCTION__, ev->ind_prim);
			kfree_skb(skb);
		}
		/* No indication */
		break;
	}

	switch (ev->cfm_prim) {
	case LLC_DATA_PRIM:
		if (!llc_data_accept_state(llc->state))
			sk->sk_write_space(sk);
		else
			rc = llc->failed_data_req = 1;
		break;
	case LLC_CONN_PRIM:
		if (sk->sk_type == SOCK_STREAM &&
		    sk->sk_state == TCP_SYN_SENT) {
			if (ev->status) {
				sk->sk_socket->state = SS_UNCONNECTED;
				sk->sk_state         = TCP_CLOSE;
			} else {
				sk->sk_socket->state = SS_CONNECTED;
				sk->sk_state         = TCP_ESTABLISHED;
			}
			sk->sk_state_change(sk);
		}
		break;
	case LLC_DISC_PRIM:
		sock_hold(sk);
		if (sk->sk_type == SOCK_STREAM && sk->sk_state == TCP_CLOSING) {
			sk->sk_socket->state = SS_UNCONNECTED;
			sk->sk_state         = TCP_CLOSE;
			sk->sk_state_change(sk);
		}
		sock_put(sk);
		break;
	case LLC_RESET_PRIM:
		/*
		 * FIXME:
		 * RESET is not being notified to upper layers for now
		 */
		printk(KERN_INFO "%s: received a reset conf!\n", __FUNCTION__);
		break;
	default:
		if (ev->cfm_prim) {
			printk(KERN_INFO "%s: received unknown %d prim!\n",
					__FUNCTION__, ev->cfm_prim);
			break;
		}
		goto out_skb_put; /* No confirmation */
	}
out_kfree_skb:
	kfree_skb(skb);
out_skb_put:
	kfree_skb(skb);
	return rc;
}

void llc_conn_send_pdu(struct sock *sk, struct sk_buff *skb)
{
	/* queue PDU to send to MAC layer */
	skb_queue_tail(&sk->sk_write_queue, skb);
	llc_conn_send_pdus(sk);
}

/**
 *	llc_conn_rtn_pdu - sends received data pdu to upper layer
 *	@sk: Active connection
 *	@skb: Received data frame
 *
 *	Sends received data pdu to upper layer (by using indicate function).
 *	Prepares service parameters (prim and prim_data). calling indication
 *	function will be done in llc_conn_state_process.
 */
void llc_conn_rtn_pdu(struct sock *sk, struct sk_buff *skb)
{
	struct llc_conn_state_ev *ev = llc_conn_ev(skb);

	ev->ind_prim = LLC_DATA_PRIM;
}

/**
 *	llc_conn_resend_i_pdu_as_cmd - resend all all unacknowledged I PDUs
 *	@sk: active connection
 *	@nr: NR
 *	@first_p_bit: p_bit value of first pdu
 *
 *	Resend all unacknowledged I PDUs, starting with the NR; send first as
 *	command PDU with P bit equal first_p_bit; if more than one send
 *	subsequent as command PDUs with P bit equal zero (0).
 */
void llc_conn_resend_i_pdu_as_cmd(struct sock *sk, u8 nr, u8 first_p_bit)
{
	struct sk_buff *skb;
	struct llc_pdu_sn *pdu;
	u16 nbr_unack_pdus;
	struct llc_sock *llc;
	u8 howmany_resend = 0;

	llc_conn_remove_acked_pdus(sk, nr, &nbr_unack_pdus);
	if (!nbr_unack_pdus)
		goto out;
	/*
	 * Process unack PDUs only if unack queue is not empty; remove
	 * appropriate PDUs, fix them up, and put them on mac_pdu_q.
	 */
	llc = llc_sk(sk);

	while ((skb = skb_dequeue(&llc->pdu_unack_q)) != NULL) {
		pdu = llc_pdu_sn_hdr(skb);
		llc_pdu_set_cmd_rsp(skb, LLC_PDU_CMD);
		llc_pdu_set_pf_bit(skb, first_p_bit);
		skb_queue_tail(&sk->sk_write_queue, skb);
		first_p_bit = 0;
		llc->vS = LLC_I_GET_NS(pdu);
		howmany_resend++;
	}
	if (howmany_resend > 0)
		llc->vS = (llc->vS + 1) % LLC_2_SEQ_NBR_MODULO;
	/* any PDUs to re-send are queued up; start sending to MAC */
	llc_conn_send_pdus(sk);
out:;
}

/**
 *	llc_conn_resend_i_pdu_as_rsp - Resend all unacknowledged I PDUs
 *	@sk: active connection.
 *	@nr: NR
 *	@first_f_bit: f_bit value of first pdu.
 *
 *	Resend all unacknowledged I PDUs, starting with the NR; send first as
 *	response PDU with F bit equal first_f_bit; if more than one send
 *	subsequent as response PDUs with F bit equal zero (0).
 */
void llc_conn_resend_i_pdu_as_rsp(struct sock *sk, u8 nr, u8 first_f_bit)
{
	struct sk_buff *skb;
	u16 nbr_unack_pdus;
	struct llc_sock *llc = llc_sk(sk);
	u8 howmany_resend = 0;

	llc_conn_remove_acked_pdus(sk, nr, &nbr_unack_pdus);
	if (!nbr_unack_pdus)
		goto out;
	/*
	 * Process unack PDUs only if unack queue is not empty; remove
	 * appropriate PDUs, fix them up, and put them on mac_pdu_q
	 */
	while ((skb = skb_dequeue(&llc->pdu_unack_q)) != NULL) {
		struct llc_pdu_sn *pdu = llc_pdu_sn_hdr(skb);

		llc_pdu_set_cmd_rsp(skb, LLC_PDU_RSP);
		llc_pdu_set_pf_bit(skb, first_f_bit);
		skb_queue_tail(&sk->sk_write_queue, skb);
		first_f_bit = 0;
		llc->vS = LLC_I_GET_NS(pdu);
		howmany_resend++;
	}
	if (howmany_resend > 0)
		llc->vS = (llc->vS + 1) % LLC_2_SEQ_NBR_MODULO;
	/* any PDUs to re-send are queued up; start sending to MAC */
	llc_conn_send_pdus(sk);
out:;
}

/**
 *	llc_conn_remove_acked_pdus - Removes acknowledged pdus from tx queue
 *	@sk: active connection
 *	nr: NR
 *	how_many_unacked: size of pdu_unack_q after removing acked pdus
 *
 *	Removes acknowledged pdus from transmit queue (pdu_unack_q). Returns
 *	the number of pdus that removed from queue.
 */
int llc_conn_remove_acked_pdus(struct sock *sk, u8 nr, u16 *how_many_unacked)
{
	int pdu_pos, i;
	struct sk_buff *skb;
	struct llc_pdu_sn *pdu;
	int nbr_acked = 0;
	struct llc_sock *llc = llc_sk(sk);
	int q_len = skb_queue_len(&llc->pdu_unack_q);

	if (!q_len)
		goto out;
	skb = skb_peek(&llc->pdu_unack_q);
	pdu = llc_pdu_sn_hdr(skb);

	/* finding position of last acked pdu in queue */
	pdu_pos = ((int)LLC_2_SEQ_NBR_MODULO + (int)nr -
			(int)LLC_I_GET_NS(pdu)) % LLC_2_SEQ_NBR_MODULO;

	for (i = 0; i < pdu_pos && i < q_len; i++) {
		skb = skb_dequeue(&llc->pdu_unack_q);
		if (skb)
			kfree_skb(skb);
		nbr_acked++;
	}
out:
	*how_many_unacked = skb_queue_len(&llc->pdu_unack_q);
	return nbr_acked;
}

/**
 *	llc_conn_send_pdus - Sends queued PDUs
 *	@sk: active connection
 *
 *	Sends queued pdus to MAC layer for transmission.
 */
static void llc_conn_send_pdus(struct sock *sk)
{
	struct sk_buff *skb;

	while ((skb = skb_dequeue(&sk->sk_write_queue)) != NULL) {
		struct llc_pdu_sn *pdu = llc_pdu_sn_hdr(skb);

		if (LLC_PDU_TYPE_IS_I(pdu) &&
		    !(skb->dev->flags & IFF_LOOPBACK)) {
			struct sk_buff *skb2 = skb_clone(skb, GFP_ATOMIC);

			skb_queue_tail(&llc_sk(sk)->pdu_unack_q, skb);
			if (!skb2)
				break;
			skb = skb2;
		}
		dev_queue_xmit(skb);
	}
}

/**
 *	llc_conn_service - finds transition and changes state of connection
 *	@sk: connection
 *	@skb: happened event
 *
 *	This function finds transition that matches with happened event, then
 *	executes related actions and finally changes state of connection.
 *	Returns 0 for success, 1 for failure.
 */
static int llc_conn_service(struct sock *sk, struct sk_buff *skb)
{
	int rc = 1;
	struct llc_sock *llc = llc_sk(sk);
	struct llc_conn_state_trans *trans;

	if (llc->state > NBR_CONN_STATES)
		goto out;
	rc = 0;
	trans = llc_qualify_conn_ev(sk, skb);
	if (trans) {
		rc = llc_exec_conn_trans_actions(sk, trans, skb);
		if (!rc && trans->next_state != NO_STATE_CHANGE) {
			llc->state = trans->next_state;
			if (!llc_data_accept_state(llc->state))
				sk->sk_state_change(sk);
		}
	}
out:
	return rc;
}

/**
 *	llc_qualify_conn_ev - finds transition for event
 *	@sk: connection
 *	@skb: happened event
 *
 *	This function finds transition that matches with happened event.
 *	Returns pointer to found transition on success, %NULL otherwise.
 */
static struct llc_conn_state_trans *llc_qualify_conn_ev(struct sock *sk,
							struct sk_buff *skb)
{
	struct llc_conn_state_trans **next_trans;
	llc_conn_ev_qfyr_t *next_qualifier;
	struct llc_conn_state_ev *ev = llc_conn_ev(skb);
	struct llc_sock *llc = llc_sk(sk);
	struct llc_conn_state *curr_state =
					&llc_conn_state_table[llc->state - 1];

	/* search thru events for this state until
	 * list exhausted or until no more
	 */
	for (next_trans = curr_state->transitions +
		llc_find_offset(llc->state - 1, ev->type);
	     (*next_trans)->ev; next_trans++) {
		if (!((*next_trans)->ev)(sk, skb)) {
			/* got POSSIBLE event match; the event may require
			 * qualification based on the values of a number of
			 * state flags; if all qualifications are met (i.e.,
			 * if all qualifying functions return success, or 0,
			 * then this is THE event we're looking for
			 */
			for (next_qualifier = (*next_trans)->ev_qualifiers;
			     next_qualifier && *next_qualifier &&
			     !(*next_qualifier)(sk, skb); next_qualifier++)
				/* nothing */;
			if (!next_qualifier || !*next_qualifier)
				/* all qualifiers executed successfully; this is
				 * our transition; return it so we can perform
				 * the associated actions & change the state
				 */
				return *next_trans;
		}
	}
	return NULL;
}

/**
 *	llc_exec_conn_trans_actions - executes related actions
 *	@sk: connection
 *	@trans: transition that it's actions must be performed
 *	@skb: event
 *
 *	Executes actions that is related to happened event. Returns 0 for
 *	success, 1 to indicate failure of at least one action.
 */
static int llc_exec_conn_trans_actions(struct sock *sk,
				       struct llc_conn_state_trans *trans,
				       struct sk_buff *skb)
{
	int rc = 0;
	llc_conn_action_t *next_action;

	for (next_action = trans->ev_actions;
	     next_action && *next_action; next_action++) {
		int rc2 = (*next_action)(sk, skb);

		if (rc2 == 2) {
			rc = rc2;
			break;
		} else if (rc2)
			rc = 1;
	}
	return rc;
}

/**
 *	__llc_lookup_established - Finds connection for the remote/local sap/mac
 *	@sap: SAP
 *	@daddr: address of remote LLC (MAC + SAP)
 *	@laddr: address of local LLC (MAC + SAP)
 *
 *	Search connection list of the SAP and finds connection using the remote
 *	mac, remote sap, local mac, and local sap. Returns pointer for
 *	connection found, %NULL otherwise.
 *	Caller has to make sure local_bh is disabled.
 */
static struct sock *__llc_lookup_established(struct llc_sap *sap,
					     struct llc_addr *daddr,
					     struct llc_addr *laddr)
{
	struct sock *rc;
	struct hlist_node *node;

	read_lock(&sap->sk_list.lock);
	sk_for_each(rc, node, &sap->sk_list.list) {
		struct llc_sock *llc = llc_sk(rc);

		if (llc->laddr.lsap == laddr->lsap &&
		    llc->daddr.lsap == daddr->lsap &&
		    llc_mac_match(llc->laddr.mac, laddr->mac) &&
		    llc_mac_match(llc->daddr.mac, daddr->mac)) {
			sock_hold(rc);
			goto found;
		}
	}
	rc = NULL;
found:
	read_unlock(&sap->sk_list.lock);
	return rc;
}

struct sock *llc_lookup_established(struct llc_sap *sap,
				    struct llc_addr *daddr,
				    struct llc_addr *laddr)
{
	struct sock *sk;

	local_bh_disable();
	sk = __llc_lookup_established(sap, daddr, laddr);
	local_bh_enable();
	return sk;
}

/**
 *	llc_lookup_listener - Finds listener for local MAC + SAP
 *	@sap: SAP
 *	@laddr: address of local LLC (MAC + SAP)
 *
 *	Search connection list of the SAP and finds connection listening on
 *	local mac, and local sap. Returns pointer for parent socket found,
 *	%NULL otherwise.
 *	Caller has to make sure local_bh is disabled.
 */
static struct sock *llc_lookup_listener(struct llc_sap *sap,
					struct llc_addr *laddr)
{
	struct sock *rc;
	struct hlist_node *node;

	read_lock(&sap->sk_list.lock);
	sk_for_each(rc, node, &sap->sk_list.list) {
		struct llc_sock *llc = llc_sk(rc);

		if (rc->sk_type == SOCK_STREAM && rc->sk_state == TCP_LISTEN &&
		    llc->laddr.lsap == laddr->lsap &&
		    (llc_mac_match(llc->laddr.mac, laddr->mac) ||
		     llc_mac_null(llc->laddr.mac))) {
			sock_hold(rc);
			goto found;
		}
	}
	rc = NULL;
found:
	read_unlock(&sap->sk_list.lock);
	return rc;
}

static struct sock *__llc_lookup(struct llc_sap *sap,
				 struct llc_addr *daddr,
				 struct llc_addr *laddr)
{
	struct sock *sk = __llc_lookup_established(sap, daddr, laddr);

	return sk ? : llc_lookup_listener(sap, laddr);
}

/**
 *	llc_data_accept_state - designates if in this state data can be sent.
 *	@state: state of connection.
 *
 *	Returns 0 if data can be sent, 1 otherwise.
 */
u8 llc_data_accept_state(u8 state)
{
	return state != LLC_CONN_STATE_NORMAL && state != LLC_CONN_STATE_BUSY &&
	       state != LLC_CONN_STATE_REJ;
}

/**
 *	llc_find_next_offset - finds offset for next category of transitions
 *	@state: state table.
 *	@offset: start offset.
 *
 *	Finds offset of next category of transitions in transition table.
 *	Returns the start index of next category.
 */
static u16 __init llc_find_next_offset(struct llc_conn_state *state, u16 offset)
{
	u16 cnt = 0;
	struct llc_conn_state_trans **next_trans;

	for (next_trans = state->transitions + offset;
	     (*next_trans)->ev; next_trans++)
		++cnt;
	return cnt;
}

/**
 *	llc_build_offset_table - builds offset table of connection
 *
 *	Fills offset table of connection state transition table
 *	(llc_offset_table).
 */
void __init llc_build_offset_table(void)
{
	struct llc_conn_state *curr_state;
	int state, ev_type, next_offset;

	for (state = 0; state < NBR_CONN_STATES; state++) {
		curr_state = &llc_conn_state_table[state];
		next_offset = 0;
		for (ev_type = 0; ev_type < NBR_CONN_EV; ev_type++) {
			llc_offset_table[state][ev_type] = next_offset;
			next_offset += llc_find_next_offset(curr_state,
							    next_offset) + 1;
		}
	}
}

/**
 *	llc_find_offset - finds start offset of category of transitions
 *	@state: state of connection
 *	@ev_type: type of happened event
 *
 *	Finds start offset of desired category of transitions. Returns the
 *	desired start offset.
 */
static int llc_find_offset(int state, int ev_type)
{
	int rc = 0;
	/* at this stage, llc_offset_table[..][2] is not important. it is for
	 * init_pf_cycle and I don't know what is it.
	 */
	switch (ev_type) {
	case LLC_CONN_EV_TYPE_PRIM:
		rc = llc_offset_table[state][0]; break;
	case LLC_CONN_EV_TYPE_PDU:
		rc = llc_offset_table[state][4]; break;
	case LLC_CONN_EV_TYPE_SIMPLE:
		rc = llc_offset_table[state][1]; break;
	case LLC_CONN_EV_TYPE_P_TMR:
	case LLC_CONN_EV_TYPE_ACK_TMR:
	case LLC_CONN_EV_TYPE_REJ_TMR:
	case LLC_CONN_EV_TYPE_BUSY_TMR:
		rc = llc_offset_table[state][3]; break;
	}
	return rc;
}

/**
 *	llc_sap_add_socket - adds a socket to a SAP
 *	@sap: SAP
 *	@sk: socket
 *
 *	This function adds a socket to sk_list of a SAP.
 */
void llc_sap_add_socket(struct llc_sap *sap, struct sock *sk)
{
	llc_sap_hold(sap);
	write_lock_bh(&sap->sk_list.lock);
	llc_sk(sk)->sap = sap;
	sk_add_node(sk, &sap->sk_list.list);
	write_unlock_bh(&sap->sk_list.lock);
}

/**
 *	llc_sap_remove_socket - removes a socket from SAP
 *	@sap: SAP
 *	@sk: socket
 *
 *	This function removes a connection from sk_list.list of a SAP if
 *	the connection was in this list.
 */
void llc_sap_remove_socket(struct llc_sap *sap, struct sock *sk)
{
	write_lock_bh(&sap->sk_list.lock);
	sk_del_node_init(sk);
	write_unlock_bh(&sap->sk_list.lock);
	llc_sap_put(sap);
}

/**
 *	llc_conn_rcv - sends received pdus to the connection state machine
 *	@sk: current connection structure.
 *	@skb: received frame.
 *
 *	Sends received pdus to the connection state machine.
 */
static int llc_conn_rcv(struct sock* sk, struct sk_buff *skb)
{
	struct llc_conn_state_ev *ev = llc_conn_ev(skb);

	ev->type   = LLC_CONN_EV_TYPE_PDU;
	ev->reason = 0;
	return llc_conn_state_process(sk, skb);
}

static struct sock *llc_create_incoming_sock(struct sock *sk,
					     struct net_device *dev,
					     struct llc_addr *saddr,
					     struct llc_addr *daddr)
{
	struct sock *newsk = llc_sk_alloc(sk->sk_net, sk->sk_family, GFP_ATOMIC,
					  sk->sk_prot);
	struct llc_sock *newllc, *llc = llc_sk(sk);

	if (!newsk)
		goto out;
	newllc = llc_sk(newsk);
	memcpy(&newllc->laddr, daddr, sizeof(newllc->laddr));
	memcpy(&newllc->daddr, saddr, sizeof(newllc->daddr));
	newllc->dev = dev;
	dev_hold(dev);
	llc_sap_add_socket(llc->sap, newsk);
	llc_sap_hold(llc->sap);
out:
	return newsk;
}

void llc_conn_handler(struct llc_sap *sap, struct sk_buff *skb)
{
	struct llc_addr saddr, daddr;
	struct sock *sk;

	llc_pdu_decode_sa(skb, saddr.mac);
	llc_pdu_decode_ssap(skb, &saddr.lsap);
	llc_pdu_decode_da(skb, daddr.mac);
	llc_pdu_decode_dsap(skb, &daddr.lsap);

	sk = __llc_lookup(sap, &saddr, &daddr);
	if (!sk)
		goto drop;

	bh_lock_sock(sk);
	/*
	 * This has to be done here and not at the upper layer ->accept
	 * method because of the way the PROCOM state machine works:
	 * it needs to set several state variables (see, for instance,
	 * llc_adm_actions_2 in net/llc/llc_c_st.c) and send a packet to
	 * the originator of the new connection, and this state has to be
	 * in the newly created struct sock private area. -acme
	 */
	if (unlikely(sk->sk_state == TCP_LISTEN)) {
		struct sock *newsk = llc_create_incoming_sock(sk, skb->dev,
							      &saddr, &daddr);
		if (!newsk)
			goto drop_unlock;
		skb_set_owner_r(skb, newsk);
	} else {
		/*
		 * Can't be skb_set_owner_r, this will be done at the
		 * llc_conn_state_process function, later on, when we will use
		 * skb_queue_rcv_skb to send it to upper layers, this is
		 * another trick required to cope with how the PROCOM state
		 * machine works. -acme
		 */
		skb->sk = sk;
	}
	if (!sock_owned_by_user(sk))
		llc_conn_rcv(sk, skb);
	else {
		dprintk("%s: adding to backlog...\n", __FUNCTION__);
		llc_set_backlog_type(skb, LLC_PACKET);
		sk_add_backlog(sk, skb);
	}
out:
	bh_unlock_sock(sk);
	sock_put(sk);
	return;
drop:
	kfree_skb(skb);
	return;
drop_unlock:
	kfree_skb(skb);
	goto out;
}

#undef LLC_REFCNT_DEBUG
#ifdef LLC_REFCNT_DEBUG
static atomic_t llc_sock_nr;
#endif

/**
 *	llc_backlog_rcv - Processes rx frames and expired timers.
 *	@sk: LLC sock (p8022 connection)
 *	@skb: queued rx frame or event
 *
 *	This function processes frames that has received and timers that has
 *	expired during sending an I pdu (refer to data_req_handler).  frames
 *	queue by llc_rcv function (llc_mac.c) and timers queue by timer
 *	callback functions(llc_c_ac.c).
 */
static int llc_backlog_rcv(struct sock *sk, struct sk_buff *skb)
{
	int rc = 0;
	struct llc_sock *llc = llc_sk(sk);

	if (likely(llc_backlog_type(skb) == LLC_PACKET)) {
		if (likely(llc->state > 1)) /* not closed */
			rc = llc_conn_rcv(sk, skb);
		else
			goto out_kfree_skb;
	} else if (llc_backlog_type(skb) == LLC_EVENT) {
		/* timer expiration event */
		if (likely(llc->state > 1))  /* not closed */
			rc = llc_conn_state_process(sk, skb);
		else
			goto out_kfree_skb;
	} else {
		printk(KERN_ERR "%s: invalid skb in backlog\n", __FUNCTION__);
		goto out_kfree_skb;
	}
out:
	return rc;
out_kfree_skb:
	kfree_skb(skb);
	goto out;
}

/**
 *     llc_sk_init - Initializes a socket with default llc values.
 *     @sk: socket to initialize.
 *
 *     Initializes a socket with default llc values.
 */
static void llc_sk_init(struct sock* sk)
{
	struct llc_sock *llc = llc_sk(sk);

	llc->state    = LLC_CONN_STATE_ADM;
	llc->inc_cntr = llc->dec_cntr = 2;
	llc->dec_step = llc->connect_step = 1;

	init_timer(&llc->ack_timer.timer);
	llc->ack_timer.expire	      = sysctl_llc2_ack_timeout;
	llc->ack_timer.timer.data     = (unsigned long)sk;
	llc->ack_timer.timer.function = llc_conn_ack_tmr_cb;

	init_timer(&llc->pf_cycle_timer.timer);
	llc->pf_cycle_timer.expire	   = sysctl_llc2_p_timeout;
	llc->pf_cycle_timer.timer.data     = (unsigned long)sk;
	llc->pf_cycle_timer.timer.function = llc_conn_pf_cycle_tmr_cb;

	init_timer(&llc->rej_sent_timer.timer);
	llc->rej_sent_timer.expire	   = sysctl_llc2_rej_timeout;
	llc->rej_sent_timer.timer.data     = (unsigned long)sk;
	llc->rej_sent_timer.timer.function = llc_conn_rej_tmr_cb;

	init_timer(&llc->busy_state_timer.timer);
	llc->busy_state_timer.expire	     = sysctl_llc2_busy_timeout;
	llc->busy_state_timer.timer.data     = (unsigned long)sk;
	llc->busy_state_timer.timer.function = llc_conn_busy_tmr_cb;

	llc->n2 = 2;   /* max retransmit */
	llc->k  = 2;   /* tx win size, will adjust dynam */
	llc->rw = 128; /* rx win size (opt and equal to
			* tx_win of remote LLC) */
	skb_queue_head_init(&llc->pdu_unack_q);
	sk->sk_backlog_rcv = llc_backlog_rcv;
}

/**
 *	llc_sk_alloc - Allocates LLC sock
 *	@family: upper layer protocol family
 *	@priority: for allocation (%GFP_KERNEL, %GFP_ATOMIC, etc)
 *
 *	Allocates a LLC sock and initializes it. Returns the new LLC sock
 *	or %NULL if there's no memory available for one
 */
struct sock *llc_sk_alloc(struct net *net, int family, gfp_t priority, struct proto *prot)
{
	struct sock *sk = sk_alloc(net, family, priority, prot, 1);

	if (!sk)
		goto out;
	llc_sk_init(sk);
	sock_init_data(NULL, sk);
#ifdef LLC_REFCNT_DEBUG
	atomic_inc(&llc_sock_nr);
	printk(KERN_DEBUG "LLC socket %p created in %s, now we have %d alive\n", sk,
		__FUNCTION__, atomic_read(&llc_sock_nr));
#endif
out:
	return sk;
}

/**
 *	llc_sk_free - Frees a LLC socket
 *	@sk - socket to free
 *
 *	Frees a LLC socket
 */
void llc_sk_free(struct sock *sk)
{
	struct llc_sock *llc = llc_sk(sk);

	llc->state = LLC_CONN_OUT_OF_SVC;
	/* Stop all (possibly) running timers */
	llc_conn_ac_stop_all_timers(sk, NULL);
#ifdef DEBUG_LLC_CONN_ALLOC
	printk(KERN_INFO "%s: unackq=%d, txq=%d\n", __FUNCTION__,
		skb_queue_len(&llc->pdu_unack_q),
		skb_queue_len(&sk->sk_write_queue));
#endif
	skb_queue_purge(&sk->sk_receive_queue);
	skb_queue_purge(&sk->sk_write_queue);
	skb_queue_purge(&llc->pdu_unack_q);
#ifdef LLC_REFCNT_DEBUG
	if (atomic_read(&sk->sk_refcnt) != 1) {
		printk(KERN_DEBUG "Destruction of LLC sock %p delayed in %s, cnt=%d\n",
			sk, __FUNCTION__, atomic_read(&sk->sk_refcnt));
		printk(KERN_DEBUG "%d LLC sockets are still alive\n",
			atomic_read(&llc_sock_nr));
	} else {
		atomic_dec(&llc_sock_nr);
		printk(KERN_DEBUG "LLC socket %p released in %s, %d are still alive\n", sk,
			__FUNCTION__, atomic_read(&llc_sock_nr));
	}
#endif
	sock_put(sk);
}

/**
 *	llc_sk_reset - resets a connection
 *	@sk: LLC socket to reset
 *
 *	Resets a connection to the out of service state. Stops its timers
 *	and frees any frames in the queues of the connection.
 */
void llc_sk_reset(struct sock *sk)
{
	struct llc_sock *llc = llc_sk(sk);

	llc_conn_ac_stop_all_timers(sk, NULL);
	skb_queue_purge(&sk->sk_write_queue);
	skb_queue_purge(&llc->pdu_unack_q);
	llc->remote_busy_flag	= 0;
	llc->cause_flag		= 0;
	llc->retry_count	= 0;
	llc_conn_set_p_flag(sk, 0);
	llc->f_flag		= 0;
	llc->s_flag		= 0;
	llc->ack_pf		= 0;
	llc->first_pdu_Ns	= 0;
	llc->ack_must_be_send	= 0;
	llc->dec_step		= 1;
	llc->inc_cntr		= 2;
	llc->dec_cntr		= 2;
	llc->X			= 0;
	llc->failed_data_req	= 0 ;
	llc->last_nr		= 0;
}