aboutsummaryrefslogtreecommitdiff
path: root/net/bluetooth/rfcomm/tty.c
blob: bd6fd0f43d2b36f3652127d51f5bdf7e797add58 (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
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
1001
1002
1003
1004
1005
1006
1007
1008
1009
1010
1011
1012
1013
1014
1015
1016
1017
1018
1019
1020
1021
1022
1023
1024
1025
1026
1027
1028
1029
1030
1031
1032
1033
1034
1035
1036
1037
1038
1039
1040
1041
1042
1043
1044
1045
1046
1047
1048
1049
1050
1051
1052
1053
1054
1055
1056
1057
1058
1059
1060
1061
1062
1063
1064
1065
1066
1067
1068
1069
1070
1071
1072
1073
1074
1075
1076
1077
1078
1079
1080
1081
1082
1083
1084
1085
1086
1087
1088
1089
1090
1091
1092
1093
1094
1095
1096
1097
1098
1099
1100
1101
1102
1103
1104
1105
1106
1107
1108
1109
1110
1111
1112
1113
1114
1115
1116
1117
1118
1119
1120
1121
1122
1123
1124
1125
1126
1127
1128
1129
1130
1131
1132
1133
1134
1135
1136
1137
1138
1139
1140
1141
1142
1143
1144
1145
1146
1147
1148
1149
1150
1151
1152
1153
1154
1155
1156
1157
1158
1159
1160
1161
1162
1163
1164
1165
1166
1167
1168
1169
1170
1171
1172
1173
1174
/*
   RFCOMM implementation for Linux Bluetooth stack (BlueZ).
   Copyright (C) 2002 Maxim Krasnyansky <maxk@qualcomm.com>
   Copyright (C) 2002 Marcel Holtmann <marcel@holtmann.org>

   This program is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License version 2 as
   published by the Free Software Foundation;

   THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
   OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
   FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT OF THIRD PARTY RIGHTS.
   IN NO EVENT SHALL THE COPYRIGHT HOLDER(S) AND AUTHOR(S) BE LIABLE FOR ANY
   CLAIM, OR ANY SPECIAL INDIRECT OR CONSEQUENTIAL DAMAGES, OR ANY DAMAGES
   WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
   ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
   OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.

   ALL LIABILITY, INCLUDING LIABILITY FOR INFRINGEMENT OF ANY PATENTS,
   COPYRIGHTS, TRADEMARKS OR OTHER RIGHTS, RELATING TO USE OF THIS
   SOFTWARE IS DISCLAIMED.
*/

/*
 * RFCOMM TTY.
 */

#include <linux/module.h>

#include <linux/tty.h>
#include <linux/tty_driver.h>
#include <linux/tty_flip.h>

#include <net/bluetooth/bluetooth.h>
#include <net/bluetooth/hci_core.h>
#include <net/bluetooth/rfcomm.h>

#define RFCOMM_TTY_MAGIC 0x6d02		/* magic number for rfcomm struct */
#define RFCOMM_TTY_PORTS RFCOMM_MAX_DEV	/* whole lotta rfcomm devices */
#define RFCOMM_TTY_MAJOR 216		/* device node major id of the usb/bluetooth.c driver */
#define RFCOMM_TTY_MINOR 0

static struct tty_driver *rfcomm_tty_driver;

struct rfcomm_dev {
	struct tty_port		port;
	struct list_head	list;

	char			name[12];
	int			id;
	unsigned long		flags;
	int			err;

	bdaddr_t		src;
	bdaddr_t		dst;
	u8			channel;

	uint			modem_status;

	struct rfcomm_dlc	*dlc;
	wait_queue_head_t       wait;

	struct device		*tty_dev;

	atomic_t		wmem_alloc;

	struct sk_buff_head	pending;
};

static LIST_HEAD(rfcomm_dev_list);
static DEFINE_SPINLOCK(rfcomm_dev_lock);

static void rfcomm_dev_data_ready(struct rfcomm_dlc *dlc, struct sk_buff *skb);
static void rfcomm_dev_state_change(struct rfcomm_dlc *dlc, int err);
static void rfcomm_dev_modem_status(struct rfcomm_dlc *dlc, u8 v24_sig);

/* ---- Device functions ---- */

/*
 * The reason this isn't actually a race, as you no doubt have a little voice
 * screaming at you in your head, is that the refcount should never actually
 * reach zero unless the device has already been taken off the list, in
 * rfcomm_dev_del(). And if that's not true, we'll hit the BUG() in
 * rfcomm_dev_destruct() anyway.
 */
static void rfcomm_dev_destruct(struct tty_port *port)
{
	struct rfcomm_dev *dev = container_of(port, struct rfcomm_dev, port);
	struct rfcomm_dlc *dlc = dev->dlc;

	BT_DBG("dev %p dlc %p", dev, dlc);

	/* Refcount should only hit zero when called from rfcomm_dev_del()
	   which will have taken us off the list. Everything else are
	   refcounting bugs. */
	BUG_ON(!list_empty(&dev->list));

	rfcomm_dlc_lock(dlc);
	/* Detach DLC if it's owned by this dev */
	if (dlc->owner == dev)
		dlc->owner = NULL;
	rfcomm_dlc_unlock(dlc);

	rfcomm_dlc_put(dlc);

	tty_unregister_device(rfcomm_tty_driver, dev->id);

	kfree(dev);

	/* It's safe to call module_put() here because socket still
	   holds reference to this module. */
	module_put(THIS_MODULE);
}

static const struct tty_port_operations rfcomm_port_ops = {
	.destruct = rfcomm_dev_destruct,
};

static struct rfcomm_dev *__rfcomm_dev_get(int id)
{
	struct rfcomm_dev *dev;

	list_for_each_entry(dev, &rfcomm_dev_list, list)
		if (dev->id == id)
			return dev;

	return NULL;
}

static struct rfcomm_dev *rfcomm_dev_get(int id)
{
	struct rfcomm_dev *dev;

	spin_lock(&rfcomm_dev_lock);

	dev = __rfcomm_dev_get(id);

	if (dev) {
		if (test_bit(RFCOMM_TTY_RELEASED, &dev->flags))
			dev = NULL;
		else
			tty_port_get(&dev->port);
	}

	spin_unlock(&rfcomm_dev_lock);

	return dev;
}

static struct device *rfcomm_get_device(struct rfcomm_dev *dev)
{
	struct hci_dev *hdev;
	struct hci_conn *conn;

	hdev = hci_get_route(&dev->dst, &dev->src);
	if (!hdev)
		return NULL;

	conn = hci_conn_hash_lookup_ba(hdev, ACL_LINK, &dev->dst);

	hci_dev_put(hdev);

	return conn ? &conn->dev : NULL;
}

static ssize_t show_address(struct device *tty_dev, struct device_attribute *attr, char *buf)
{
	struct rfcomm_dev *dev = dev_get_drvdata(tty_dev);
	return sprintf(buf, "%pMR\n", &dev->dst);
}

static ssize_t show_channel(struct device *tty_dev, struct device_attribute *attr, char *buf)
{
	struct rfcomm_dev *dev = dev_get_drvdata(tty_dev);
	return sprintf(buf, "%d\n", dev->channel);
}

static DEVICE_ATTR(address, S_IRUGO, show_address, NULL);
static DEVICE_ATTR(channel, S_IRUGO, show_channel, NULL);

static int rfcomm_dev_add(struct rfcomm_dev_req *req, struct rfcomm_dlc *dlc)
{
	struct rfcomm_dev *dev, *entry;
	struct list_head *head = &rfcomm_dev_list;
	int err = 0;

	BT_DBG("id %d channel %d", req->dev_id, req->channel);

	dev = kzalloc(sizeof(struct rfcomm_dev), GFP_KERNEL);
	if (!dev)
		return -ENOMEM;

	spin_lock(&rfcomm_dev_lock);

	if (req->dev_id < 0) {
		dev->id = 0;

		list_for_each_entry(entry, &rfcomm_dev_list, list) {
			if (entry->id != dev->id)
				break;

			dev->id++;
			head = &entry->list;
		}
	} else {
		dev->id = req->dev_id;

		list_for_each_entry(entry, &rfcomm_dev_list, list) {
			if (entry->id == dev->id) {
				err = -EADDRINUSE;
				goto out;
			}

			if (entry->id > dev->id - 1)
				break;

			head = &entry->list;
		}
	}

	if ((dev->id < 0) || (dev->id > RFCOMM_MAX_DEV - 1)) {
		err = -ENFILE;
		goto out;
	}

	sprintf(dev->name, "rfcomm%d", dev->id);

	list_add(&dev->list, head);

	bacpy(&dev->src, &req->src);
	bacpy(&dev->dst, &req->dst);
	dev->channel = req->channel;

	dev->flags = req->flags &
		((1 << RFCOMM_RELEASE_ONHUP) | (1 << RFCOMM_REUSE_DLC));

	tty_port_init(&dev->port);
	dev->port.ops = &rfcomm_port_ops;
	init_waitqueue_head(&dev->wait);

	skb_queue_head_init(&dev->pending);

	rfcomm_dlc_lock(dlc);

	if (req->flags & (1 << RFCOMM_REUSE_DLC)) {
		struct sock *sk = dlc->owner;
		struct sk_buff *skb;

		BUG_ON(!sk);

		rfcomm_dlc_throttle(dlc);

		while ((skb = skb_dequeue(&sk->sk_receive_queue))) {
			skb_orphan(skb);
			skb_queue_tail(&dev->pending, skb);
			atomic_sub(skb->len, &sk->sk_rmem_alloc);
		}
	}

	dlc->data_ready   = rfcomm_dev_data_ready;
	dlc->state_change = rfcomm_dev_state_change;
	dlc->modem_status = rfcomm_dev_modem_status;

	dlc->owner = dev;
	dev->dlc   = dlc;

	rfcomm_dev_modem_status(dlc, dlc->remote_v24_sig);

	rfcomm_dlc_unlock(dlc);

	/* It's safe to call __module_get() here because socket already
	   holds reference to this module. */
	__module_get(THIS_MODULE);

out:
	spin_unlock(&rfcomm_dev_lock);

	if (err < 0)
		goto free;

	dev->tty_dev = tty_port_register_device(&dev->port, rfcomm_tty_driver,
			dev->id, NULL);
	if (IS_ERR(dev->tty_dev)) {
		err = PTR_ERR(dev->tty_dev);
		list_del(&dev->list);
		goto free;
	}

	dev_set_drvdata(dev->tty_dev, dev);

	if (device_create_file(dev->tty_dev, &dev_attr_address) < 0)
		BT_ERR("Failed to create address attribute");

	if (device_create_file(dev->tty_dev, &dev_attr_channel) < 0)
		BT_ERR("Failed to create channel attribute");

	return dev->id;

free:
	kfree(dev);
	return err;
}

static void rfcomm_dev_del(struct rfcomm_dev *dev)
{
	unsigned long flags;
	BT_DBG("dev %p", dev);

	BUG_ON(test_and_set_bit(RFCOMM_TTY_RELEASED, &dev->flags));

	spin_lock_irqsave(&dev->port.lock, flags);
	if (dev->port.count > 0) {
		spin_unlock_irqrestore(&dev->port.lock, flags);
		return;
	}
	spin_unlock_irqrestore(&dev->port.lock, flags);

	spin_lock(&rfcomm_dev_lock);
	list_del_init(&dev->list);
	spin_unlock(&rfcomm_dev_lock);

	tty_port_put(&dev->port);
}

/* ---- Send buffer ---- */
static inline unsigned int rfcomm_room(struct rfcomm_dlc *dlc)
{
	/* We can't let it be zero, because we don't get a callback
	   when tx_credits becomes nonzero, hence we'd never wake up */
	return dlc->mtu * (dlc->tx_credits?:1);
}

static void rfcomm_wfree(struct sk_buff *skb)
{
	struct rfcomm_dev *dev = (void *) skb->sk;
	struct tty_struct *tty = dev->port.tty;
	atomic_sub(skb->truesize, &dev->wmem_alloc);
	if (test_bit(RFCOMM_TTY_ATTACHED, &dev->flags) && tty)
		tty_wakeup(tty);
	tty_port_put(&dev->port);
}

static void rfcomm_set_owner_w(struct sk_buff *skb, struct rfcomm_dev *dev)
{
	tty_port_get(&dev->port);
	atomic_add(skb->truesize, &dev->wmem_alloc);
	skb->sk = (void *) dev;
	skb->destructor = rfcomm_wfree;
}

static struct sk_buff *rfcomm_wmalloc(struct rfcomm_dev *dev, unsigned long size, gfp_t priority)
{
	if (atomic_read(&dev->wmem_alloc) < rfcomm_room(dev->dlc)) {
		struct sk_buff *skb = alloc_skb(size, priority);
		if (skb) {
			rfcomm_set_owner_w(skb, dev);
			return skb;
		}
	}
	return NULL;
}

/* ---- Device IOCTLs ---- */

#define NOCAP_FLAGS ((1 << RFCOMM_REUSE_DLC) | (1 << RFCOMM_RELEASE_ONHUP))

static int rfcomm_create_dev(struct sock *sk, void __user *arg)
{
	struct rfcomm_dev_req req;
	struct rfcomm_dlc *dlc;
	int id;

	if (copy_from_user(&req, arg, sizeof(req)))
		return -EFAULT;

	BT_DBG("sk %p dev_id %d flags 0x%x", sk, req.dev_id, req.flags);

	if (req.flags != NOCAP_FLAGS && !capable(CAP_NET_ADMIN))
		return -EPERM;

	if (req.flags & (1 << RFCOMM_REUSE_DLC)) {
		/* Socket must be connected */
		if (sk->sk_state != BT_CONNECTED)
			return -EBADFD;

		dlc = rfcomm_pi(sk)->dlc;
		rfcomm_dlc_hold(dlc);
	} else {
		dlc = rfcomm_dlc_alloc(GFP_KERNEL);
		if (!dlc)
			return -ENOMEM;
	}

	id = rfcomm_dev_add(&req, dlc);
	if (id < 0) {
		rfcomm_dlc_put(dlc);
		return id;
	}

	if (req.flags & (1 << RFCOMM_REUSE_DLC)) {
		/* DLC is now used by device.
		 * Socket must be disconnected */
		sk->sk_state = BT_CLOSED;
	}

	return id;
}

static int rfcomm_release_dev(void __user *arg)
{
	struct rfcomm_dev_req req;
	struct rfcomm_dev *dev;

	if (copy_from_user(&req, arg, sizeof(req)))
		return -EFAULT;

	BT_DBG("dev_id %d flags 0x%x", req.dev_id, req.flags);

	dev = rfcomm_dev_get(req.dev_id);
	if (!dev)
		return -ENODEV;

	if (dev->flags != NOCAP_FLAGS && !capable(CAP_NET_ADMIN)) {
		tty_port_put(&dev->port);
		return -EPERM;
	}

	if (req.flags & (1 << RFCOMM_HANGUP_NOW))
		rfcomm_dlc_close(dev->dlc, 0);

	/* Shut down TTY synchronously before freeing rfcomm_dev */
	if (dev->port.tty)
		tty_vhangup(dev->port.tty);

	if (!test_bit(RFCOMM_RELEASE_ONHUP, &dev->flags))
		rfcomm_dev_del(dev);
	tty_port_put(&dev->port);
	return 0;
}

static int rfcomm_get_dev_list(void __user *arg)
{
	struct rfcomm_dev *dev;
	struct rfcomm_dev_list_req *dl;
	struct rfcomm_dev_info *di;
	int n = 0, size, err;
	u16 dev_num;

	BT_DBG("");

	if (get_user(dev_num, (u16 __user *) arg))
		return -EFAULT;

	if (!dev_num || dev_num > (PAGE_SIZE * 4) / sizeof(*di))
		return -EINVAL;

	size = sizeof(*dl) + dev_num * sizeof(*di);

	dl = kzalloc(size, GFP_KERNEL);
	if (!dl)
		return -ENOMEM;

	di = dl->dev_info;

	spin_lock(&rfcomm_dev_lock);

	list_for_each_entry(dev, &rfcomm_dev_list, list) {
		if (test_bit(RFCOMM_TTY_RELEASED, &dev->flags))
			continue;
		(di + n)->id      = dev->id;
		(di + n)->flags   = dev->flags;
		(di + n)->state   = dev->dlc->state;
		(di + n)->channel = dev->channel;
		bacpy(&(di + n)->src, &dev->src);
		bacpy(&(di + n)->dst, &dev->dst);
		if (++n >= dev_num)
			break;
	}

	spin_unlock(&rfcomm_dev_lock);

	dl->dev_num = n;
	size = sizeof(*dl) + n * sizeof(*di);

	err = copy_to_user(arg, dl, size);
	kfree(dl);

	return err ? -EFAULT : 0;
}

static int rfcomm_get_dev_info(void __user *arg)
{
	struct rfcomm_dev *dev;
	struct rfcomm_dev_info di;
	int err = 0;

	BT_DBG("");

	if (copy_from_user(&di, arg, sizeof(di)))
		return -EFAULT;

	dev = rfcomm_dev_get(di.id);
	if (!dev)
		return -ENODEV;

	di.flags   = dev->flags;
	di.channel = dev->channel;
	di.state   = dev->dlc->state;
	bacpy(&di.src, &dev->src);
	bacpy(&di.dst, &dev->dst);

	if (copy_to_user(arg, &di, sizeof(di)))
		err = -EFAULT;

	tty_port_put(&dev->port);
	return err;
}

int rfcomm_dev_ioctl(struct sock *sk, unsigned int cmd, void __user *arg)
{
	BT_DBG("cmd %d arg %p", cmd, arg);

	switch (cmd) {
	case RFCOMMCREATEDEV:
		return rfcomm_create_dev(sk, arg);

	case RFCOMMRELEASEDEV:
		return rfcomm_release_dev(arg);

	case RFCOMMGETDEVLIST:
		return rfcomm_get_dev_list(arg);

	case RFCOMMGETDEVINFO:
		return rfcomm_get_dev_info(arg);
	}

	return -EINVAL;
}

/* ---- DLC callbacks ---- */
static void rfcomm_dev_data_ready(struct rfcomm_dlc *dlc, struct sk_buff *skb)
{
	struct rfcomm_dev *dev = dlc->owner;
	struct tty_struct *tty;

	if (!dev) {
		kfree_skb(skb);
		return;
	}

	tty = dev->port.tty;
	if (!tty || !skb_queue_empty(&dev->pending)) {
		skb_queue_tail(&dev->pending, skb);
		return;
	}

	BT_DBG("dlc %p tty %p len %d", dlc, tty, skb->len);

	tty_insert_flip_string(tty, skb->data, skb->len);
	tty_flip_buffer_push(tty);

	kfree_skb(skb);
}

static void rfcomm_dev_state_change(struct rfcomm_dlc *dlc, int err)
{
	struct rfcomm_dev *dev = dlc->owner;
	if (!dev)
		return;

	BT_DBG("dlc %p dev %p err %d", dlc, dev, err);

	dev->err = err;
	wake_up_interruptible(&dev->wait);

	if (dlc->state == BT_CLOSED) {
		if (!dev->port.tty) {
			if (test_bit(RFCOMM_RELEASE_ONHUP, &dev->flags)) {
				/* Drop DLC lock here to avoid deadlock
				 * 1. rfcomm_dev_get will take rfcomm_dev_lock
				 *    but in rfcomm_dev_add there's lock order:
				 *    rfcomm_dev_lock -> dlc lock
				 * 2. tty_port_put will deadlock if it's
				 *    the last reference
				 */
				rfcomm_dlc_unlock(dlc);
				if (rfcomm_dev_get(dev->id) == NULL) {
					rfcomm_dlc_lock(dlc);
					return;
				}

				rfcomm_dev_del(dev);
				tty_port_put(&dev->port);
				rfcomm_dlc_lock(dlc);
			}
		} else
			tty_hangup(dev->port.tty);
	}
}

static void rfcomm_dev_modem_status(struct rfcomm_dlc *dlc, u8 v24_sig)
{
	struct rfcomm_dev *dev = dlc->owner;
	if (!dev)
		return;

	BT_DBG("dlc %p dev %p v24_sig 0x%02x", dlc, dev, v24_sig);

	if ((dev->modem_status & TIOCM_CD) && !(v24_sig & RFCOMM_V24_DV)) {
		if (dev->port.tty && !C_CLOCAL(dev->port.tty))
			tty_hangup(dev->port.tty);
	}

	dev->modem_status =
		((v24_sig & RFCOMM_V24_RTC) ? (TIOCM_DSR | TIOCM_DTR) : 0) |
		((v24_sig & RFCOMM_V24_RTR) ? (TIOCM_RTS | TIOCM_CTS) : 0) |
		((v24_sig & RFCOMM_V24_IC)  ? TIOCM_RI : 0) |
		((v24_sig & RFCOMM_V24_DV)  ? TIOCM_CD : 0);
}

/* ---- TTY functions ---- */
static void rfcomm_tty_copy_pending(struct rfcomm_dev *dev)
{
	struct tty_struct *tty = dev->port.tty;
	struct sk_buff *skb;
	int inserted = 0;

	if (!tty)
		return;

	BT_DBG("dev %p tty %p", dev, tty);

	rfcomm_dlc_lock(dev->dlc);

	while ((skb = skb_dequeue(&dev->pending))) {
		inserted += tty_insert_flip_string(tty, skb->data, skb->len);
		kfree_skb(skb);
	}

	rfcomm_dlc_unlock(dev->dlc);

	if (inserted > 0)
		tty_flip_buffer_push(tty);
}

static int rfcomm_tty_open(struct tty_struct *tty, struct file *filp)
{
	DECLARE_WAITQUEUE(wait, current);
	struct rfcomm_dev *dev;
	struct rfcomm_dlc *dlc;
	unsigned long flags;
	int err, id;

	id = tty->index;

	BT_DBG("tty %p id %d", tty, id);

	/* We don't leak this refcount. For reasons which are not entirely
	   clear, the TTY layer will call our ->close() method even if the
	   open fails. We decrease the refcount there, and decreasing it
	   here too would cause breakage. */
	dev = rfcomm_dev_get(id);
	if (!dev)
		return -ENODEV;

	BT_DBG("dev %p dst %pMR channel %d opened %d", dev, &dev->dst,
	       dev->channel, dev->port.count);

	spin_lock_irqsave(&dev->port.lock, flags);
	if (++dev->port.count > 1) {
		spin_unlock_irqrestore(&dev->port.lock, flags);
		return 0;
	}
	spin_unlock_irqrestore(&dev->port.lock, flags);

	dlc = dev->dlc;

	/* Attach TTY and open DLC */

	rfcomm_dlc_lock(dlc);
	tty->driver_data = dev;
	dev->port.tty = tty;
	rfcomm_dlc_unlock(dlc);
	set_bit(RFCOMM_TTY_ATTACHED, &dev->flags);

	err = rfcomm_dlc_open(dlc, &dev->src, &dev->dst, dev->channel);
	if (err < 0)
		return err;

	/* Wait for DLC to connect */
	add_wait_queue(&dev->wait, &wait);
	while (1) {
		set_current_state(TASK_INTERRUPTIBLE);

		if (dlc->state == BT_CLOSED) {
			err = -dev->err;
			break;
		}

		if (dlc->state == BT_CONNECTED)
			break;

		if (signal_pending(current)) {
			err = -EINTR;
			break;
		}

		tty_unlock(tty);
		schedule();
		tty_lock(tty);
	}
	set_current_state(TASK_RUNNING);
	remove_wait_queue(&dev->wait, &wait);

	if (err == 0)
		device_move(dev->tty_dev, rfcomm_get_device(dev),
			    DPM_ORDER_DEV_AFTER_PARENT);

	rfcomm_tty_copy_pending(dev);

	rfcomm_dlc_unthrottle(dev->dlc);

	return err;
}

static void rfcomm_tty_close(struct tty_struct *tty, struct file *filp)
{
	struct rfcomm_dev *dev = (struct rfcomm_dev *) tty->driver_data;
	unsigned long flags;

	if (!dev)
		return;

	BT_DBG("tty %p dev %p dlc %p opened %d", tty, dev, dev->dlc,
						dev->port.count);

	spin_lock_irqsave(&dev->port.lock, flags);
	if (!--dev->port.count) {
		spin_unlock_irqrestore(&dev->port.lock, flags);
		if (dev->tty_dev->parent)
			device_move(dev->tty_dev, NULL, DPM_ORDER_DEV_LAST);

		/* Close DLC and dettach TTY */
		rfcomm_dlc_close(dev->dlc, 0);

		clear_bit(RFCOMM_TTY_ATTACHED, &dev->flags);

		rfcomm_dlc_lock(dev->dlc);
		tty->driver_data = NULL;
		dev->port.tty = NULL;
		rfcomm_dlc_unlock(dev->dlc);

		if (test_bit(RFCOMM_TTY_RELEASED, &dev->flags)) {
			spin_lock(&rfcomm_dev_lock);
			list_del_init(&dev->list);
			spin_unlock(&rfcomm_dev_lock);

			tty_port_put(&dev->port);
		}
	} else
		spin_unlock_irqrestore(&dev->port.lock, flags);

	tty_port_put(&dev->port);
}

static int rfcomm_tty_write(struct tty_struct *tty, const unsigned char *buf, int count)
{
	struct rfcomm_dev *dev = (struct rfcomm_dev *) tty->driver_data;
	struct rfcomm_dlc *dlc = dev->dlc;
	struct sk_buff *skb;
	int err = 0, sent = 0, size;

	BT_DBG("tty %p count %d", tty, count);

	while (count) {
		size = min_t(uint, count, dlc->mtu);

		skb = rfcomm_wmalloc(dev, size + RFCOMM_SKB_RESERVE, GFP_ATOMIC);

		if (!skb)
			break;

		skb_reserve(skb, RFCOMM_SKB_HEAD_RESERVE);

		memcpy(skb_put(skb, size), buf + sent, size);

		err = rfcomm_dlc_send(dlc, skb);
		if (err < 0) {
			kfree_skb(skb);
			break;
		}

		sent  += size;
		count -= size;
	}

	return sent ? sent : err;
}

static int rfcomm_tty_write_room(struct tty_struct *tty)
{
	struct rfcomm_dev *dev = (struct rfcomm_dev *) tty->driver_data;
	int room;

	BT_DBG("tty %p", tty);

	if (!dev || !dev->dlc)
		return 0;

	room = rfcomm_room(dev->dlc) - atomic_read(&dev->wmem_alloc);
	if (room < 0)
		room = 0;

	return room;
}

static int rfcomm_tty_ioctl(struct tty_struct *tty, unsigned int cmd, unsigned long arg)
{
	BT_DBG("tty %p cmd 0x%02x", tty, cmd);

	switch (cmd) {
	case TCGETS:
		BT_DBG("TCGETS is not supported");
		return -ENOIOCTLCMD;

	case TCSETS:
		BT_DBG("TCSETS is not supported");
		return -ENOIOCTLCMD;

	case TIOCMIWAIT:
		BT_DBG("TIOCMIWAIT");
		break;

	case TIOCGSERIAL:
		BT_ERR("TIOCGSERIAL is not supported");
		return -ENOIOCTLCMD;

	case TIOCSSERIAL:
		BT_ERR("TIOCSSERIAL is not supported");
		return -ENOIOCTLCMD;

	case TIOCSERGSTRUCT:
		BT_ERR("TIOCSERGSTRUCT is not supported");
		return -ENOIOCTLCMD;

	case TIOCSERGETLSR:
		BT_ERR("TIOCSERGETLSR is not supported");
		return -ENOIOCTLCMD;

	case TIOCSERCONFIG:
		BT_ERR("TIOCSERCONFIG is not supported");
		return -ENOIOCTLCMD;

	default:
		return -ENOIOCTLCMD;	/* ioctls which we must ignore */

	}

	return -ENOIOCTLCMD;
}

static void rfcomm_tty_set_termios(struct tty_struct *tty, struct ktermios *old)
{
	struct ktermios *new = &tty->termios;
	int old_baud_rate = tty_termios_baud_rate(old);
	int new_baud_rate = tty_termios_baud_rate(new);

	u8 baud, data_bits, stop_bits, parity, x_on, x_off;
	u16 changes = 0;

	struct rfcomm_dev *dev = (struct rfcomm_dev *) tty->driver_data;

	BT_DBG("tty %p termios %p", tty, old);

	if (!dev || !dev->dlc || !dev->dlc->session)
		return;

	/* Handle turning off CRTSCTS */
	if ((old->c_cflag & CRTSCTS) && !(new->c_cflag & CRTSCTS))
		BT_DBG("Turning off CRTSCTS unsupported");

	/* Parity on/off and when on, odd/even */
	if (((old->c_cflag & PARENB) != (new->c_cflag & PARENB)) ||
			((old->c_cflag & PARODD) != (new->c_cflag & PARODD))) {
		changes |= RFCOMM_RPN_PM_PARITY;
		BT_DBG("Parity change detected.");
	}

	/* Mark and space parity are not supported! */
	if (new->c_cflag & PARENB) {
		if (new->c_cflag & PARODD) {
			BT_DBG("Parity is ODD");
			parity = RFCOMM_RPN_PARITY_ODD;
		} else {
			BT_DBG("Parity is EVEN");
			parity = RFCOMM_RPN_PARITY_EVEN;
		}
	} else {
		BT_DBG("Parity is OFF");
		parity = RFCOMM_RPN_PARITY_NONE;
	}

	/* Setting the x_on / x_off characters */
	if (old->c_cc[VSTOP] != new->c_cc[VSTOP]) {
		BT_DBG("XOFF custom");
		x_on = new->c_cc[VSTOP];
		changes |= RFCOMM_RPN_PM_XON;
	} else {
		BT_DBG("XOFF default");
		x_on = RFCOMM_RPN_XON_CHAR;
	}

	if (old->c_cc[VSTART] != new->c_cc[VSTART]) {
		BT_DBG("XON custom");
		x_off = new->c_cc[VSTART];
		changes |= RFCOMM_RPN_PM_XOFF;
	} else {
		BT_DBG("XON default");
		x_off = RFCOMM_RPN_XOFF_CHAR;
	}

	/* Handle setting of stop bits */
	if ((old->c_cflag & CSTOPB) != (new->c_cflag & CSTOPB))
		changes |= RFCOMM_RPN_PM_STOP;

	/* POSIX does not support 1.5 stop bits and RFCOMM does not
	 * support 2 stop bits. So a request for 2 stop bits gets
	 * translated to 1.5 stop bits */
	if (new->c_cflag & CSTOPB)
		stop_bits = RFCOMM_RPN_STOP_15;
	else
		stop_bits = RFCOMM_RPN_STOP_1;

	/* Handle number of data bits [5-8] */
	if ((old->c_cflag & CSIZE) != (new->c_cflag & CSIZE))
		changes |= RFCOMM_RPN_PM_DATA;

	switch (new->c_cflag & CSIZE) {
	case CS5:
		data_bits = RFCOMM_RPN_DATA_5;
		break;
	case CS6:
		data_bits = RFCOMM_RPN_DATA_6;
		break;
	case CS7:
		data_bits = RFCOMM_RPN_DATA_7;
		break;
	case CS8:
		data_bits = RFCOMM_RPN_DATA_8;
		break;
	default:
		data_bits = RFCOMM_RPN_DATA_8;
		break;
	}

	/* Handle baudrate settings */
	if (old_baud_rate != new_baud_rate)
		changes |= RFCOMM_RPN_PM_BITRATE;

	switch (new_baud_rate) {
	case 2400:
		baud = RFCOMM_RPN_BR_2400;
		break;
	case 4800:
		baud = RFCOMM_RPN_BR_4800;
		break;
	case 7200:
		baud = RFCOMM_RPN_BR_7200;
		break;
	case 9600:
		baud = RFCOMM_RPN_BR_9600;
		break;
	case 19200:
		baud = RFCOMM_RPN_BR_19200;
		break;
	case 38400:
		baud = RFCOMM_RPN_BR_38400;
		break;
	case 57600:
		baud = RFCOMM_RPN_BR_57600;
		break;
	case 115200:
		baud = RFCOMM_RPN_BR_115200;
		break;
	case 230400:
		baud = RFCOMM_RPN_BR_230400;
		break;
	default:
		/* 9600 is standard accordinag to the RFCOMM specification */
		baud = RFCOMM_RPN_BR_9600;
		break;

	}

	if (changes)
		rfcomm_send_rpn(dev->dlc->session, 1, dev->dlc->dlci, baud,
				data_bits, stop_bits, parity,
				RFCOMM_RPN_FLOW_NONE, x_on, x_off, changes);
}

static void rfcomm_tty_throttle(struct tty_struct *tty)
{
	struct rfcomm_dev *dev = (struct rfcomm_dev *) tty->driver_data;

	BT_DBG("tty %p dev %p", tty, dev);

	rfcomm_dlc_throttle(dev->dlc);
}

static void rfcomm_tty_unthrottle(struct tty_struct *tty)
{
	struct rfcomm_dev *dev = (struct rfcomm_dev *) tty->driver_data;

	BT_DBG("tty %p dev %p", tty, dev);

	rfcomm_dlc_unthrottle(dev->dlc);
}

static int rfcomm_tty_chars_in_buffer(struct tty_struct *tty)
{
	struct rfcomm_dev *dev = (struct rfcomm_dev *) tty->driver_data;

	BT_DBG("tty %p dev %p", tty, dev);

	if (!dev || !dev->dlc)
		return 0;

	if (!skb_queue_empty(&dev->dlc->tx_queue))
		return dev->dlc->mtu;

	return 0;
}

static void rfcomm_tty_flush_buffer(struct tty_struct *tty)
{
	struct rfcomm_dev *dev = (struct rfcomm_dev *) tty->driver_data;

	BT_DBG("tty %p dev %p", tty, dev);

	if (!dev || !dev->dlc)
		return;

	skb_queue_purge(&dev->dlc->tx_queue);
	tty_wakeup(tty);
}

static void rfcomm_tty_send_xchar(struct tty_struct *tty, char ch)
{
	BT_DBG("tty %p ch %c", tty, ch);
}

static void rfcomm_tty_wait_until_sent(struct tty_struct *tty, int timeout)
{
	BT_DBG("tty %p timeout %d", tty, timeout);
}

static void rfcomm_tty_hangup(struct tty_struct *tty)
{
	struct rfcomm_dev *dev = (struct rfcomm_dev *) tty->driver_data;

	BT_DBG("tty %p dev %p", tty, dev);

	if (!dev)
		return;

	rfcomm_tty_flush_buffer(tty);

	if (test_bit(RFCOMM_RELEASE_ONHUP, &dev->flags)) {
		if (rfcomm_dev_get(dev->id) == NULL)
			return;
		rfcomm_dev_del(dev);
		tty_port_put(&dev->port);
	}
}

static int rfcomm_tty_tiocmget(struct tty_struct *tty)
{
	struct rfcomm_dev *dev = (struct rfcomm_dev *) tty->driver_data;

	BT_DBG("tty %p dev %p", tty, dev);

	return dev->modem_status;
}

static int rfcomm_tty_tiocmset(struct tty_struct *tty, unsigned int set, unsigned int clear)
{
	struct rfcomm_dev *dev = (struct rfcomm_dev *) tty->driver_data;
	struct rfcomm_dlc *dlc = dev->dlc;
	u8 v24_sig;

	BT_DBG("tty %p dev %p set 0x%02x clear 0x%02x", tty, dev, set, clear);

	rfcomm_dlc_get_modem_status(dlc, &v24_sig);

	if (set & TIOCM_DSR || set & TIOCM_DTR)
		v24_sig |= RFCOMM_V24_RTC;
	if (set & TIOCM_RTS || set & TIOCM_CTS)
		v24_sig |= RFCOMM_V24_RTR;
	if (set & TIOCM_RI)
		v24_sig |= RFCOMM_V24_IC;
	if (set & TIOCM_CD)
		v24_sig |= RFCOMM_V24_DV;

	if (clear & TIOCM_DSR || clear & TIOCM_DTR)
		v24_sig &= ~RFCOMM_V24_RTC;
	if (clear & TIOCM_RTS || clear & TIOCM_CTS)
		v24_sig &= ~RFCOMM_V24_RTR;
	if (clear & TIOCM_RI)
		v24_sig &= ~RFCOMM_V24_IC;
	if (clear & TIOCM_CD)
		v24_sig &= ~RFCOMM_V24_DV;

	rfcomm_dlc_set_modem_status(dlc, v24_sig);

	return 0;
}

/* ---- TTY structure ---- */

static const struct tty_operations rfcomm_ops = {
	.open			= rfcomm_tty_open,
	.close			= rfcomm_tty_close,
	.write			= rfcomm_tty_write,
	.write_room		= rfcomm_tty_write_room,
	.chars_in_buffer	= rfcomm_tty_chars_in_buffer,
	.flush_buffer		= rfcomm_tty_flush_buffer,
	.ioctl			= rfcomm_tty_ioctl,
	.throttle		= rfcomm_tty_throttle,
	.unthrottle		= rfcomm_tty_unthrottle,
	.set_termios		= rfcomm_tty_set_termios,
	.send_xchar		= rfcomm_tty_send_xchar,
	.hangup			= rfcomm_tty_hangup,
	.wait_until_sent	= rfcomm_tty_wait_until_sent,
	.tiocmget		= rfcomm_tty_tiocmget,
	.tiocmset		= rfcomm_tty_tiocmset,
};

int __init rfcomm_init_ttys(void)
{
	int error;

	rfcomm_tty_driver = alloc_tty_driver(RFCOMM_TTY_PORTS);
	if (!rfcomm_tty_driver)
		return -ENOMEM;

	rfcomm_tty_driver->driver_name	= "rfcomm";
	rfcomm_tty_driver->name		= "rfcomm";
	rfcomm_tty_driver->major	= RFCOMM_TTY_MAJOR;
	rfcomm_tty_driver->minor_start	= RFCOMM_TTY_MINOR;
	rfcomm_tty_driver->type		= TTY_DRIVER_TYPE_SERIAL;
	rfcomm_tty_driver->subtype	= SERIAL_TYPE_NORMAL;
	rfcomm_tty_driver->flags	= TTY_DRIVER_REAL_RAW | TTY_DRIVER_DYNAMIC_DEV;
	rfcomm_tty_driver->init_termios	= tty_std_termios;
	rfcomm_tty_driver->init_termios.c_cflag	= B9600 | CS8 | CREAD | HUPCL | CLOCAL;
	rfcomm_tty_driver->init_termios.c_lflag &= ~ICANON;
	tty_set_operations(rfcomm_tty_driver, &rfcomm_ops);

	error = tty_register_driver(rfcomm_tty_driver);
	if (error) {
		BT_ERR("Can't register RFCOMM TTY driver");
		put_tty_driver(rfcomm_tty_driver);
		return error;
	}

	BT_INFO("RFCOMM TTY layer initialized");

	return 0;
}

void rfcomm_cleanup_ttys(void)
{
	tty_unregister_driver(rfcomm_tty_driver);
	put_tty_driver(rfcomm_tty_driver);
}