summaryrefslogtreecommitdiff
path: root/net/can/af_can.c
blob: a8dcaa49675ae2fa848a732452673096d17d2803 (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
/*
 * af_can.c - Protocol family CAN core module
 *            (used by different CAN protocol modules)
 *
 * Copyright (c) 2002-2007 Volkswagen Group Electronic Research
 * 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 name of Volkswagen nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * Alternatively, provided that this notice is retained in full, this
 * software may be distributed under the terms of the GNU General
 * Public License ("GPL") version 2, in which case the provisions of the
 * GPL apply INSTEAD OF those given above.
 *
 * The provided data structures and external interfaces from this code
 * are not restricted to be used by modules with a GPL compatible license.
 *
 * 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.
 *
 * Send feedback to <socketcan-users@lists.berlios.de>
 *
 */

#include <linux/module.h>
#include <linux/init.h>
#include <linux/kmod.h>
#include <linux/slab.h>
#include <linux/list.h>
#include <linux/spinlock.h>
#include <linux/rcupdate.h>
#include <linux/uaccess.h>
#include <linux/net.h>
#include <linux/netdevice.h>
#include <linux/socket.h>
#include <linux/if_ether.h>
#include <linux/if_arp.h>
#include <linux/skbuff.h>
#include <linux/can.h>
#include <linux/can/core.h>
#include <net/net_namespace.h>
#include <net/sock.h>

#include "af_can.h"

static __initdata const char banner[] = KERN_INFO
	"can: controller area network core (" CAN_VERSION_STRING ")\n";

MODULE_DESCRIPTION("Controller Area Network PF_CAN core");
MODULE_LICENSE("Dual BSD/GPL");
MODULE_AUTHOR("Urs Thuermann <urs.thuermann@volkswagen.de>, "
	      "Oliver Hartkopp <oliver.hartkopp@volkswagen.de>");

MODULE_ALIAS_NETPROTO(PF_CAN);

static int stats_timer __read_mostly = 1;
module_param(stats_timer, int, S_IRUGO);
MODULE_PARM_DESC(stats_timer, "enable timer for statistics (default:on)");

/* receive filters subscribed for 'all' CAN devices */
struct dev_rcv_lists can_rx_alldev_list;
static DEFINE_SPINLOCK(can_rcvlists_lock);

static struct kmem_cache *rcv_cache __read_mostly;

/* table of registered CAN protocols */
static struct can_proto *proto_tab[CAN_NPROTO] __read_mostly;
static DEFINE_MUTEX(proto_tab_lock);

struct timer_list can_stattimer;   /* timer for statistics update */
struct s_stats    can_stats;       /* packet statistics */
struct s_pstats   can_pstats;      /* receive list statistics */

/*
 * af_can socket functions
 */

int can_ioctl(struct socket *sock, unsigned int cmd, unsigned long arg)
{
	struct sock *sk = sock->sk;

	switch (cmd) {

	case SIOCGSTAMP:
		return sock_get_timestamp(sk, (struct timeval __user *)arg);

	default:
		return -ENOIOCTLCMD;
	}
}
EXPORT_SYMBOL(can_ioctl);

static void can_sock_destruct(struct sock *sk)
{
	skb_queue_purge(&sk->sk_receive_queue);
}

static struct can_proto *can_try_module_get(int protocol)
{
	struct can_proto *cp;

	rcu_read_lock();
	cp = rcu_dereference(proto_tab[protocol]);
	if (cp && !try_module_get(cp->prot->owner))
		cp = NULL;
	rcu_read_unlock();

	return cp;
}

static int can_create(struct net *net, struct socket *sock, int protocol,
		      int kern)
{
	struct sock *sk;
	struct can_proto *cp;
	int err = 0;

	sock->state = SS_UNCONNECTED;

	if (protocol < 0 || protocol >= CAN_NPROTO)
		return -EINVAL;

	if (!net_eq(net, &init_net))
		return -EAFNOSUPPORT;

	cp = can_try_module_get(protocol);

#ifdef CONFIG_MODULES
	if (!cp) {
		/* try to load protocol module if kernel is modular */

		err = request_module("can-proto-%d", protocol);

		/*
		 * In case of error we only print a message but don't
		 * return the error code immediately.  Below we will
		 * return -EPROTONOSUPPORT
		 */
		if (err && printk_ratelimit())
			printk(KERN_ERR "can: request_module "
			       "(can-proto-%d) failed.\n", protocol);

		cp = can_try_module_get(protocol);
	}
#endif

	/* check for available protocol and correct usage */

	if (!cp)
		return -EPROTONOSUPPORT;

	if (cp->type != sock->type) {
		err = -EPROTOTYPE;
		goto errout;
	}

	sock->ops = cp->ops;

	sk = sk_alloc(net, PF_CAN, GFP_KERNEL, cp->prot);
	if (!sk) {
		err = -ENOMEM;
		goto errout;
	}

	sock_init_data(sock, sk);
	sk->sk_destruct = can_sock_destruct;

	if (sk->sk_prot->init)
		err = sk->sk_prot->init(sk);

	if (err) {
		/* release sk on errors */
		sock_orphan(sk);
		sock_put(sk);
	}

 errout:
	module_put(cp->prot->owner);
	return err;
}

/*
 * af_can tx path
 */

/**
 * can_send - transmit a CAN frame (optional with local loopback)
 * @skb: pointer to socket buffer with CAN frame in data section
 * @loop: loopback for listeners on local CAN sockets (recommended default!)
 *
 * Due to the loopback this routine must not be called from hardirq context.
 *
 * Return:
 *  0 on success
 *  -ENETDOWN when the selected interface is down
 *  -ENOBUFS on full driver queue (see net_xmit_errno())
 *  -ENOMEM when local loopback failed at calling skb_clone()
 *  -EPERM when trying to send on a non-CAN interface
 *  -EINVAL when the skb->data does not contain a valid CAN frame
 */
int can_send(struct sk_buff *skb, int loop)
{
	struct sk_buff *newskb = NULL;
	struct can_frame *cf = (struct can_frame *)skb->data;
	int err;

	if (skb->len != sizeof(struct can_frame) || cf->can_dlc > 8) {
		kfree_skb(skb);
		return -EINVAL;
	}

	if (skb->dev->type != ARPHRD_CAN) {
		kfree_skb(skb);
		return -EPERM;
	}

	if (!(skb->dev->flags & IFF_UP)) {
		kfree_skb(skb);
		return -ENETDOWN;
	}

	skb->protocol = htons(ETH_P_CAN);
	skb_reset_network_header(skb);
	skb_reset_transport_header(skb);

	if (loop) {
		/* local loopback of sent CAN frames */

		/* indication for the CAN driver: do loopback */
		skb->pkt_type = PACKET_LOOPBACK;

		/*
		 * The reference to the originating sock may be required
		 * by the receiving socket to check whether the frame is
		 * its own. Example: can_raw sockopt CAN_RAW_RECV_OWN_MSGS
		 * Therefore we have to ensure that skb->sk remains the
		 * reference to the originating sock by restoring skb->sk
		 * after each skb_clone() or skb_orphan() usage.
		 */

		if (!(skb->dev->flags & IFF_ECHO)) {
			/*
			 * If the interface is not capable to do loopback
			 * itself, we do it here.
			 */
			newskb = skb_clone(skb, GFP_ATOMIC);
			if (!newskb) {
				kfree_skb(skb);
				return -ENOMEM;
			}

			newskb->sk = skb->sk;
			newskb->ip_summed = CHECKSUM_UNNECESSARY;
			newskb->pkt_type = PACKET_BROADCAST;
		}
	} else {
		/* indication for the CAN driver: no loopback required */
		skb->pkt_type = PACKET_HOST;
	}

	/* send to netdevice */
	err = dev_queue_xmit(skb);
	if (err > 0)
		err = net_xmit_errno(err);

	if (err) {
		kfree_skb(newskb);
		return err;
	}

	if (newskb)
		netif_rx_ni(newskb);

	/* update statistics */
	can_stats.tx_frames++;
	can_stats.tx_frames_delta++;

	return 0;
}
EXPORT_SYMBOL(can_send);

/*
 * af_can rx path
 */

static struct dev_rcv_lists *find_dev_rcv_lists(struct net_device *dev)
{
	if (!dev)
		return &can_rx_alldev_list;
	else
		return (struct dev_rcv_lists *)dev->ml_priv;
}

/**
 * find_rcv_list - determine optimal filterlist inside device filter struct
 * @can_id: pointer to CAN identifier of a given can_filter
 * @mask: pointer to CAN mask of a given can_filter
 * @d: pointer to the device filter struct
 *
 * Description:
 *  Returns the optimal filterlist to reduce the filter handling in the
 *  receive path. This function is called by service functions that need
 *  to register or unregister a can_filter in the filter lists.
 *
 *  A filter matches in general, when
 *
 *          <received_can_id> & mask == can_id & mask
 *
 *  so every bit set in the mask (even CAN_EFF_FLAG, CAN_RTR_FLAG) describe
 *  relevant bits for the filter.
 *
 *  The filter can be inverted (CAN_INV_FILTER bit set in can_id) or it can
 *  filter for error frames (CAN_ERR_FLAG bit set in mask). For error frames
 *  there is a special filterlist and a special rx path filter handling.
 *
 * Return:
 *  Pointer to optimal filterlist for the given can_id/mask pair.
 *  Constistency checked mask.
 *  Reduced can_id to have a preprocessed filter compare value.
 */
static struct hlist_head *find_rcv_list(canid_t *can_id, canid_t *mask,
					struct dev_rcv_lists *d)
{
	canid_t inv = *can_id & CAN_INV_FILTER; /* save flag before masking */

	/* filter for error frames in extra filterlist */
	if (*mask & CAN_ERR_FLAG) {
		/* clear CAN_ERR_FLAG in filter entry */
		*mask &= CAN_ERR_MASK;
		return &d->rx[RX_ERR];
	}

	/* with cleared CAN_ERR_FLAG we have a simple mask/value filterpair */

#define CAN_EFF_RTR_FLAGS (CAN_EFF_FLAG | CAN_RTR_FLAG)

	/* ensure valid values in can_mask for 'SFF only' frame filtering */
	if ((*mask & CAN_EFF_FLAG) && !(*can_id & CAN_EFF_FLAG))
		*mask &= (CAN_SFF_MASK | CAN_EFF_RTR_FLAGS);

	/* reduce condition testing at receive time */
	*can_id &= *mask;

	/* inverse can_id/can_mask filter */
	if (inv)
		return &d->rx[RX_INV];

	/* mask == 0 => no condition testing at receive time */
	if (!(*mask))
		return &d->rx[RX_ALL];

	/* extra filterlists for the subscription of a single non-RTR can_id */
	if (((*mask & CAN_EFF_RTR_FLAGS) == CAN_EFF_RTR_FLAGS) &&
	    !(*can_id & CAN_RTR_FLAG)) {

		if (*can_id & CAN_EFF_FLAG) {
			if (*mask == (CAN_EFF_MASK | CAN_EFF_RTR_FLAGS)) {
				/* RFC: a future use-case for hash-tables? */
				return &d->rx[RX_EFF];
			}
		} else {
			if (*mask == (CAN_SFF_MASK | CAN_EFF_RTR_FLAGS))
				return &d->rx_sff[*can_id];
		}
	}

	/* default: filter via can_id/can_mask */
	return &d->rx[RX_FIL];
}

/**
 * can_rx_register - subscribe CAN frames from a specific interface
 * @dev: pointer to netdevice (NULL => subcribe from 'all' CAN devices list)
 * @can_id: CAN identifier (see description)
 * @mask: CAN mask (see description)
 * @func: callback function on filter match
 * @data: returned parameter for callback function
 * @ident: string for calling module indentification
 *
 * Description:
 *  Invokes the callback function with the received sk_buff and the given
 *  parameter 'data' on a matching receive filter. A filter matches, when
 *
 *          <received_can_id> & mask == can_id & mask
 *
 *  The filter can be inverted (CAN_INV_FILTER bit set in can_id) or it can
 *  filter for error frames (CAN_ERR_FLAG bit set in mask).
 *
 *  The provided pointer to the sk_buff is guaranteed to be valid as long as
 *  the callback function is running. The callback function must *not* free
 *  the given sk_buff while processing it's task. When the given sk_buff is
 *  needed after the end of the callback function it must be cloned inside
 *  the callback function with skb_clone().
 *
 * Return:
 *  0 on success
 *  -ENOMEM on missing cache mem to create subscription entry
 *  -ENODEV unknown device
 */
int can_rx_register(struct net_device *dev, canid_t can_id, canid_t mask,
		    void (*func)(struct sk_buff *, void *), void *data,
		    char *ident)
{
	struct receiver *r;
	struct hlist_head *rl;
	struct dev_rcv_lists *d;
	int err = 0;

	/* insert new receiver  (dev,canid,mask) -> (func,data) */

	if (dev && dev->type != ARPHRD_CAN)
		return -ENODEV;

	r = kmem_cache_alloc(rcv_cache, GFP_KERNEL);
	if (!r)
		return -ENOMEM;

	spin_lock(&can_rcvlists_lock);

	d = find_dev_rcv_lists(dev);
	if (d) {
		rl = find_rcv_list(&can_id, &mask, d);

		r->can_id  = can_id;
		r->mask    = mask;
		r->matches = 0;
		r->func    = func;
		r->data    = data;
		r->ident   = ident;

		hlist_add_head_rcu(&r->list, rl);
		d->entries++;

		can_pstats.rcv_entries++;
		if (can_pstats.rcv_entries_max < can_pstats.rcv_entries)
			can_pstats.rcv_entries_max = can_pstats.rcv_entries;
	} else {
		kmem_cache_free(rcv_cache, r);
		err = -ENODEV;
	}

	spin_unlock(&can_rcvlists_lock);

	return err;
}
EXPORT_SYMBOL(can_rx_register);

/*
 * can_rx_delete_receiver - rcu callback for single receiver entry removal
 */
static void can_rx_delete_receiver(struct rcu_head *rp)
{
	struct receiver *r = container_of(rp, struct receiver, rcu);

	kmem_cache_free(rcv_cache, r);
}

/**
 * can_rx_unregister - unsubscribe CAN frames from a specific interface
 * @dev: pointer to netdevice (NULL => unsubcribe from 'all' CAN devices list)
 * @can_id: CAN identifier
 * @mask: CAN mask
 * @func: callback function on filter match
 * @data: returned parameter for callback function
 *
 * Description:
 *  Removes subscription entry depending on given (subscription) values.
 */
void can_rx_unregister(struct net_device *dev, canid_t can_id, canid_t mask,
		       void (*func)(struct sk_buff *, void *), void *data)
{
	struct receiver *r = NULL;
	struct hlist_head *rl;
	struct hlist_node *next;
	struct dev_rcv_lists *d;

	if (dev && dev->type != ARPHRD_CAN)
		return;

	spin_lock(&can_rcvlists_lock);

	d = find_dev_rcv_lists(dev);
	if (!d) {
		printk(KERN_ERR "BUG: receive list not found for "
		       "dev %s, id %03X, mask %03X\n",
		       DNAME(dev), can_id, mask);
		goto out;
	}

	rl = find_rcv_list(&can_id, &mask, d);

	/*
	 * Search the receiver list for the item to delete.  This should
	 * exist, since no receiver may be unregistered that hasn't
	 * been registered before.
	 */

	hlist_for_each_entry_rcu(r, next, rl, list) {
		if (r->can_id == can_id && r->mask == mask &&
		    r->func == func && r->data == data)
			break;
	}

	/*
	 * Check for bugs in CAN protocol implementations:
	 * If no matching list item was found, the list cursor variable next
	 * will be NULL, while r will point to the last item of the list.
	 */

	if (!next) {
		printk(KERN_ERR "BUG: receive list entry not found for "
		       "dev %s, id %03X, mask %03X\n",
		       DNAME(dev), can_id, mask);
		r = NULL;
		goto out;
	}

	hlist_del_rcu(&r->list);
	d->entries--;

	if (can_pstats.rcv_entries > 0)
		can_pstats.rcv_entries--;

	/* remove device structure requested by NETDEV_UNREGISTER */
	if (d->remove_on_zero_entries && !d->entries) {
		kfree(d);
		dev->ml_priv = NULL;
	}

 out:
	spin_unlock(&can_rcvlists_lock);

	/* schedule the receiver item for deletion */
	if (r)
		call_rcu(&r->rcu, can_rx_delete_receiver);
}
EXPORT_SYMBOL(can_rx_unregister);

static inline void deliver(struct sk_buff *skb, struct receiver *r)
{
	r->func(skb, r->data);
	r->matches++;
}

static int can_rcv_filter(struct dev_rcv_lists *d, struct sk_buff *skb)
{
	struct receiver *r;
	struct hlist_node *n;
	int matches = 0;
	struct can_frame *cf = (struct can_frame *)skb->data;
	canid_t can_id = cf->can_id;

	if (d->entries == 0)
		return 0;

	if (can_id & CAN_ERR_FLAG) {
		/* check for error frame entries only */
		hlist_for_each_entry_rcu(r, n, &d->rx[RX_ERR], list) {
			if (can_id & r->mask) {
				deliver(skb, r);
				matches++;
			}
		}
		return matches;
	}

	/* check for unfiltered entries */
	hlist_for_each_entry_rcu(r, n, &d->rx[RX_ALL], list) {
		deliver(skb, r);
		matches++;
	}

	/* check for can_id/mask entries */
	hlist_for_each_entry_rcu(r, n, &d->rx[RX_FIL], list) {
		if ((can_id & r->mask) == r->can_id) {
			deliver(skb, r);
			matches++;
		}
	}

	/* check for inverted can_id/mask entries */
	hlist_for_each_entry_rcu(r, n, &d->rx[RX_INV], list) {
		if ((can_id & r->mask) != r->can_id) {
			deliver(skb, r);
			matches++;
		}
	}

	/* check filterlists for single non-RTR can_ids */
	if (can_id & CAN_RTR_FLAG)
		return matches;

	if (can_id & CAN_EFF_FLAG) {
		hlist_for_each_entry_rcu(r, n, &d->rx[RX_EFF], list) {
			if (r->can_id == can_id) {
				deliver(skb, r);
				matches++;
			}
		}
	} else {
		can_id &= CAN_SFF_MASK;
		hlist_for_each_entry_rcu(r, n, &d->rx_sff[can_id], list) {
			deliver(skb, r);
			matches++;
		}
	}

	return matches;
}

static int can_rcv(struct sk_buff *skb, struct net_device *dev,
		   struct packet_type *pt, struct net_device *orig_dev)
{
	struct dev_rcv_lists *d;
	struct can_frame *cf = (struct can_frame *)skb->data;
	int matches;

	if (!net_eq(dev_net(dev), &init_net))
		goto drop;

	if (WARN_ONCE(dev->type != ARPHRD_CAN ||
		      skb->len != sizeof(struct can_frame) ||
		      cf->can_dlc > 8,
		      "PF_CAN: dropped non conform skbuf: "
		      "dev type %d, len %d, can_dlc %d\n",
		      dev->type, skb->len, cf->can_dlc))
		goto drop;

	/* update statistics */
	can_stats.rx_frames++;
	can_stats.rx_frames_delta++;

	rcu_read_lock();

	/* deliver the packet to sockets listening on all devices */
	matches = can_rcv_filter(&can_rx_alldev_list, skb);

	/* find receive list for this device */
	d = find_dev_rcv_lists(dev);
	if (d)
		matches += can_rcv_filter(d, skb);

	rcu_read_unlock();

	/* consume the skbuff allocated by the netdevice driver */
	consume_skb(skb);

	if (matches > 0) {
		can_stats.matches++;
		can_stats.matches_delta++;
	}

	return NET_RX_SUCCESS;

drop:
	kfree_skb(skb);
	return NET_RX_DROP;
}

/*
 * af_can protocol functions
 */

/**
 * can_proto_register - register CAN transport protocol
 * @cp: pointer to CAN protocol structure
 *
 * Return:
 *  0 on success
 *  -EINVAL invalid (out of range) protocol number
 *  -EBUSY  protocol already in use
 *  -ENOBUF if proto_register() fails
 */
int can_proto_register(struct can_proto *cp)
{
	int proto = cp->protocol;
	int err = 0;

	if (proto < 0 || proto >= CAN_NPROTO) {
		printk(KERN_ERR "can: protocol number %d out of range\n",
		       proto);
		return -EINVAL;
	}

	err = proto_register(cp->prot, 0);
	if (err < 0)
		return err;

	mutex_lock(&proto_tab_lock);

	if (proto_tab[proto]) {
		printk(KERN_ERR "can: protocol %d already registered\n",
		       proto);
		err = -EBUSY;
	} else
		rcu_assign_pointer(proto_tab[proto], cp);

	mutex_unlock(&proto_tab_lock);

	if (err < 0)
		proto_unregister(cp->prot);

	return err;
}
EXPORT_SYMBOL(can_proto_register);

/**
 * can_proto_unregister - unregister CAN transport protocol
 * @cp: pointer to CAN protocol structure
 */
void can_proto_unregister(struct can_proto *cp)
{
	int proto = cp->protocol;

	mutex_lock(&proto_tab_lock);
	BUG_ON(proto_tab[proto] != cp);
	rcu_assign_pointer(proto_tab[proto], NULL);
	mutex_unlock(&proto_tab_lock);

	synchronize_rcu();

	proto_unregister(cp->prot);
}
EXPORT_SYMBOL(can_proto_unregister);

/*
 * af_can notifier to create/remove CAN netdevice specific structs
 */
static int can_notifier(struct notifier_block *nb, unsigned long msg,
			void *data)
{
	struct net_device *dev = (struct net_device *)data;
	struct dev_rcv_lists *d;

	if (!net_eq(dev_net(dev), &init_net))
		return NOTIFY_DONE;

	if (dev->type != ARPHRD_CAN)
		return NOTIFY_DONE;

	switch (msg) {

	case NETDEV_REGISTER:

		/* create new dev_rcv_lists for this device */
		d = kzalloc(sizeof(*d), GFP_KERNEL);
		if (!d) {
			printk(KERN_ERR
			       "can: allocation of receive list failed\n");
			return NOTIFY_DONE;
		}
		BUG_ON(dev->ml_priv);
		dev->ml_priv = d;

		break;

	case NETDEV_UNREGISTER:
		spin_lock(&can_rcvlists_lock);

		d = dev->ml_priv;
		if (d) {
			if (d->entries)
				d->remove_on_zero_entries = 1;
			else {
				kfree(d);
				dev->ml_priv = NULL;
			}
		} else
			printk(KERN_ERR "can: notifier: receive list not "
			       "found for dev %s\n", dev->name);

		spin_unlock(&can_rcvlists_lock);

		break;
	}

	return NOTIFY_DONE;
}

/*
 * af_can module init/exit functions
 */

static struct packet_type can_packet __read_mostly = {
	.type = cpu_to_be16(ETH_P_CAN),
	.dev  = NULL,
	.func = can_rcv,
};

static const struct net_proto_family can_family_ops = {
	.family = PF_CAN,
	.create = can_create,
	.owner  = THIS_MODULE,
};

/* notifier block for netdevice event */
static struct notifier_block can_netdev_notifier __read_mostly = {
	.notifier_call = can_notifier,
};

static __init int can_init(void)
{
	printk(banner);

	memset(&can_rx_alldev_list, 0, sizeof(can_rx_alldev_list));

	rcv_cache = kmem_cache_create("can_receiver", sizeof(struct receiver),
				      0, 0, NULL);
	if (!rcv_cache)
		return -ENOMEM;

	if (stats_timer) {
		/* the statistics are updated every second (timer triggered) */
		setup_timer(&can_stattimer, can_stat_update, 0);
		mod_timer(&can_stattimer, round_jiffies(jiffies + HZ));
	} else
		can_stattimer.function = NULL;

	can_init_proc();

	/* protocol register */
	sock_register(&can_family_ops);
	register_netdevice_notifier(&can_netdev_notifier);
	dev_add_pack(&can_packet);

	return 0;
}

static __exit void can_exit(void)
{
	struct net_device *dev;

	if (stats_timer)
		del_timer(&can_stattimer);

	can_remove_proc();

	/* protocol unregister */
	dev_remove_pack(&can_packet);
	unregister_netdevice_notifier(&can_netdev_notifier);
	sock_unregister(PF_CAN);

	/* remove created dev_rcv_lists from still registered CAN devices */
	rcu_read_lock();
	for_each_netdev_rcu(&init_net, dev) {
		if (dev->type == ARPHRD_CAN && dev->ml_priv){

			struct dev_rcv_lists *d = dev->ml_priv;

			BUG_ON(d->entries);
			kfree(d);
			dev->ml_priv = NULL;
		}
	}
	rcu_read_unlock();

	rcu_barrier(); /* Wait for completion of call_rcu()'s */

	kmem_cache_destroy(rcv_cache);
}

module_init(can_init);
module_exit(can_exit);