1 /*
2 * af_can.c - Protocol family CAN core module
3 * (used by different CAN protocol modules)
4 *
5 * Copyright (c) 2002-2007 Volkswagen Group Electronic Research
6 * All rights reserved.
7 *
8 * Redistribution and use in source and binary forms, with or without
9 * modification, are permitted provided that the following conditions
10 * are met:
11 * 1. Redistributions of source code must retain the above copyright
12 * notice, this list of conditions and the following disclaimer.
13 * 2. Redistributions in binary form must reproduce the above copyright
14 * notice, this list of conditions and the following disclaimer in the
15 * documentation and/or other materials provided with the distribution.
16 * 3. Neither the name of Volkswagen nor the names of its contributors
17 * may be used to endorse or promote products derived from this software
18 * without specific prior written permission.
19 *
20 * Alternatively, provided that this notice is retained in full, this
21 * software may be distributed under the terms of the GNU General
22 * Public License ("GPL") version 2, in which case the provisions of the
23 * GPL apply INSTEAD OF those given above.
24 *
25 * The provided data structures and external interfaces from this code
26 * are not restricted to be used by modules with a GPL compatible license.
27 *
28 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
29 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
30 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
31 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
32 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
33 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
34 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
35 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
36 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
37 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
38 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH
39 * DAMAGE.
40 *
41 * Send feedback to <socketcan-users@lists.berlios.de>
42 *
43 */
44
45 #include <linux/module.h>
46 #include <linux/init.h>
47 #include <linux/kmod.h>
48 #include <linux/slab.h>
49 #include <linux/list.h>
50 #include <linux/spinlock.h>
51 #include <linux/rcupdate.h>
52 #include <linux/uaccess.h>
53 #include <linux/net.h>
54 #include <linux/netdevice.h>
55 #include <linux/socket.h>
56 #include <linux/if_ether.h>
57 #include <linux/if_arp.h>
58 #include <linux/skbuff.h>
59 #include <linux/can.h>
60 #include <linux/can/core.h>
61 #include <net/net_namespace.h>
62 #include <net/sock.h>
63
64 #include "af_can.h"
65
66 static __initdata const char banner[] = KERN_INFO
67 "can: controller area network core (" CAN_VERSION_STRING ")\n";
68
69 MODULE_DESCRIPTION("Controller Area Network PF_CAN core");
70 MODULE_LICENSE("Dual BSD/GPL");
71 MODULE_AUTHOR("Urs Thuermann <urs.thuermann@volkswagen.de>, "
72 "Oliver Hartkopp <oliver.hartkopp@volkswagen.de>");
73
74 MODULE_ALIAS_NETPROTO(PF_CAN);
75
76 static int stats_timer __read_mostly = 1;
77 module_param(stats_timer, int, S_IRUGO);
78 MODULE_PARM_DESC(stats_timer, "enable timer for statistics (default:on)");
79
80 HLIST_HEAD(can_rx_dev_list);
81 static struct dev_rcv_lists can_rx_alldev_list;
82 static DEFINE_SPINLOCK(can_rcvlists_lock);
83
84 static struct kmem_cache *rcv_cache __read_mostly;
85
86 /* table of registered CAN protocols */
87 static struct can_proto *proto_tab[CAN_NPROTO] __read_mostly;
88 static DEFINE_SPINLOCK(proto_tab_lock);
89
90 struct timer_list can_stattimer; /* timer for statistics update */
91 struct s_stats can_stats; /* packet statistics */
92 struct s_pstats can_pstats; /* receive list statistics */
93
94 /*
95 * af_can socket functions
96 */
97
can_ioctl(struct socket * sock,unsigned int cmd,unsigned long arg)98 static int can_ioctl(struct socket *sock, unsigned int cmd, unsigned long arg)
99 {
100 struct sock *sk = sock->sk;
101
102 switch (cmd) {
103
104 case SIOCGSTAMP:
105 return sock_get_timestamp(sk, (struct timeval __user *)arg);
106
107 default:
108 return -ENOIOCTLCMD;
109 }
110 }
111
can_sock_destruct(struct sock * sk)112 static void can_sock_destruct(struct sock *sk)
113 {
114 skb_queue_purge(&sk->sk_receive_queue);
115 }
116
can_create(struct net * net,struct socket * sock,int protocol)117 static int can_create(struct net *net, struct socket *sock, int protocol)
118 {
119 struct sock *sk;
120 struct can_proto *cp;
121 int err = 0;
122
123 sock->state = SS_UNCONNECTED;
124
125 if (protocol < 0 || protocol >= CAN_NPROTO)
126 return -EINVAL;
127
128 if (net != &init_net)
129 return -EAFNOSUPPORT;
130
131 #ifdef CONFIG_MODULES
132 /* try to load protocol module kernel is modular */
133 if (!proto_tab[protocol]) {
134 err = request_module("can-proto-%d", protocol);
135
136 /*
137 * In case of error we only print a message but don't
138 * return the error code immediately. Below we will
139 * return -EPROTONOSUPPORT
140 */
141 if (err && printk_ratelimit())
142 printk(KERN_ERR "can: request_module "
143 "(can-proto-%d) failed.\n", protocol);
144 }
145 #endif
146
147 spin_lock(&proto_tab_lock);
148 cp = proto_tab[protocol];
149 if (cp && !try_module_get(cp->prot->owner))
150 cp = NULL;
151 spin_unlock(&proto_tab_lock);
152
153 /* check for available protocol and correct usage */
154
155 if (!cp)
156 return -EPROTONOSUPPORT;
157
158 if (cp->type != sock->type) {
159 err = -EPROTONOSUPPORT;
160 goto errout;
161 }
162
163 if (cp->capability >= 0 && !capable(cp->capability)) {
164 err = -EPERM;
165 goto errout;
166 }
167
168 sock->ops = cp->ops;
169
170 sk = sk_alloc(net, PF_CAN, GFP_KERNEL, cp->prot);
171 if (!sk) {
172 err = -ENOMEM;
173 goto errout;
174 }
175
176 sock_init_data(sock, sk);
177 sk->sk_destruct = can_sock_destruct;
178
179 if (sk->sk_prot->init)
180 err = sk->sk_prot->init(sk);
181
182 if (err) {
183 /* release sk on errors */
184 sock_orphan(sk);
185 sock_put(sk);
186 }
187
188 errout:
189 module_put(cp->prot->owner);
190 return err;
191 }
192
193 /*
194 * af_can tx path
195 */
196
197 /**
198 * can_send - transmit a CAN frame (optional with local loopback)
199 * @skb: pointer to socket buffer with CAN frame in data section
200 * @loop: loopback for listeners on local CAN sockets (recommended default!)
201 *
202 * Return:
203 * 0 on success
204 * -ENETDOWN when the selected interface is down
205 * -ENOBUFS on full driver queue (see net_xmit_errno())
206 * -ENOMEM when local loopback failed at calling skb_clone()
207 * -EPERM when trying to send on a non-CAN interface
208 * -EINVAL when the skb->data does not contain a valid CAN frame
209 */
can_send(struct sk_buff * skb,int loop)210 int can_send(struct sk_buff *skb, int loop)
211 {
212 struct sk_buff *newskb = NULL;
213 struct can_frame *cf = (struct can_frame *)skb->data;
214 int err;
215
216 if (skb->len != sizeof(struct can_frame) || cf->can_dlc > 8) {
217 kfree_skb(skb);
218 return -EINVAL;
219 }
220
221 if (skb->dev->type != ARPHRD_CAN) {
222 kfree_skb(skb);
223 return -EPERM;
224 }
225
226 if (!(skb->dev->flags & IFF_UP)) {
227 kfree_skb(skb);
228 return -ENETDOWN;
229 }
230
231 skb->protocol = htons(ETH_P_CAN);
232 skb_reset_network_header(skb);
233 skb_reset_transport_header(skb);
234
235 if (loop) {
236 /* local loopback of sent CAN frames */
237
238 /* indication for the CAN driver: do loopback */
239 skb->pkt_type = PACKET_LOOPBACK;
240
241 /*
242 * The reference to the originating sock may be required
243 * by the receiving socket to check whether the frame is
244 * its own. Example: can_raw sockopt CAN_RAW_RECV_OWN_MSGS
245 * Therefore we have to ensure that skb->sk remains the
246 * reference to the originating sock by restoring skb->sk
247 * after each skb_clone() or skb_orphan() usage.
248 */
249
250 if (!(skb->dev->flags & IFF_ECHO)) {
251 /*
252 * If the interface is not capable to do loopback
253 * itself, we do it here.
254 */
255 newskb = skb_clone(skb, GFP_ATOMIC);
256 if (!newskb) {
257 kfree_skb(skb);
258 return -ENOMEM;
259 }
260
261 newskb->sk = skb->sk;
262 newskb->ip_summed = CHECKSUM_UNNECESSARY;
263 newskb->pkt_type = PACKET_BROADCAST;
264 }
265 } else {
266 /* indication for the CAN driver: no loopback required */
267 skb->pkt_type = PACKET_HOST;
268 }
269
270 /* send to netdevice */
271 err = dev_queue_xmit(skb);
272 if (err > 0)
273 err = net_xmit_errno(err);
274
275 if (err) {
276 if (newskb)
277 kfree_skb(newskb);
278 return err;
279 }
280
281 if (newskb)
282 netif_rx(newskb);
283
284 /* update statistics */
285 can_stats.tx_frames++;
286 can_stats.tx_frames_delta++;
287
288 return 0;
289 }
290 EXPORT_SYMBOL(can_send);
291
292 /*
293 * af_can rx path
294 */
295
find_dev_rcv_lists(struct net_device * dev)296 static struct dev_rcv_lists *find_dev_rcv_lists(struct net_device *dev)
297 {
298 struct dev_rcv_lists *d = NULL;
299 struct hlist_node *n;
300
301 /*
302 * find receive list for this device
303 *
304 * The hlist_for_each_entry*() macros curse through the list
305 * using the pointer variable n and set d to the containing
306 * struct in each list iteration. Therefore, after list
307 * iteration, d is unmodified when the list is empty, and it
308 * points to last list element, when the list is non-empty
309 * but no match in the loop body is found. I.e. d is *not*
310 * NULL when no match is found. We can, however, use the
311 * cursor variable n to decide if a match was found.
312 */
313
314 hlist_for_each_entry_rcu(d, n, &can_rx_dev_list, list) {
315 if (d->dev == dev)
316 break;
317 }
318
319 return n ? d : NULL;
320 }
321
322 /**
323 * find_rcv_list - determine optimal filterlist inside device filter struct
324 * @can_id: pointer to CAN identifier of a given can_filter
325 * @mask: pointer to CAN mask of a given can_filter
326 * @d: pointer to the device filter struct
327 *
328 * Description:
329 * Returns the optimal filterlist to reduce the filter handling in the
330 * receive path. This function is called by service functions that need
331 * to register or unregister a can_filter in the filter lists.
332 *
333 * A filter matches in general, when
334 *
335 * <received_can_id> & mask == can_id & mask
336 *
337 * so every bit set in the mask (even CAN_EFF_FLAG, CAN_RTR_FLAG) describe
338 * relevant bits for the filter.
339 *
340 * The filter can be inverted (CAN_INV_FILTER bit set in can_id) or it can
341 * filter for error frames (CAN_ERR_FLAG bit set in mask). For error frames
342 * there is a special filterlist and a special rx path filter handling.
343 *
344 * Return:
345 * Pointer to optimal filterlist for the given can_id/mask pair.
346 * Constistency checked mask.
347 * Reduced can_id to have a preprocessed filter compare value.
348 */
find_rcv_list(canid_t * can_id,canid_t * mask,struct dev_rcv_lists * d)349 static struct hlist_head *find_rcv_list(canid_t *can_id, canid_t *mask,
350 struct dev_rcv_lists *d)
351 {
352 canid_t inv = *can_id & CAN_INV_FILTER; /* save flag before masking */
353
354 /* filter for error frames in extra filterlist */
355 if (*mask & CAN_ERR_FLAG) {
356 /* clear CAN_ERR_FLAG in filter entry */
357 *mask &= CAN_ERR_MASK;
358 return &d->rx[RX_ERR];
359 }
360
361 /* with cleared CAN_ERR_FLAG we have a simple mask/value filterpair */
362
363 #define CAN_EFF_RTR_FLAGS (CAN_EFF_FLAG | CAN_RTR_FLAG)
364
365 /* ensure valid values in can_mask for 'SFF only' frame filtering */
366 if ((*mask & CAN_EFF_FLAG) && !(*can_id & CAN_EFF_FLAG))
367 *mask &= (CAN_SFF_MASK | CAN_EFF_RTR_FLAGS);
368
369 /* reduce condition testing at receive time */
370 *can_id &= *mask;
371
372 /* inverse can_id/can_mask filter */
373 if (inv)
374 return &d->rx[RX_INV];
375
376 /* mask == 0 => no condition testing at receive time */
377 if (!(*mask))
378 return &d->rx[RX_ALL];
379
380 /* extra filterlists for the subscription of a single non-RTR can_id */
381 if (((*mask & CAN_EFF_RTR_FLAGS) == CAN_EFF_RTR_FLAGS)
382 && !(*can_id & CAN_RTR_FLAG)) {
383
384 if (*can_id & CAN_EFF_FLAG) {
385 if (*mask == (CAN_EFF_MASK | CAN_EFF_RTR_FLAGS)) {
386 /* RFC: a future use-case for hash-tables? */
387 return &d->rx[RX_EFF];
388 }
389 } else {
390 if (*mask == (CAN_SFF_MASK | CAN_EFF_RTR_FLAGS))
391 return &d->rx_sff[*can_id];
392 }
393 }
394
395 /* default: filter via can_id/can_mask */
396 return &d->rx[RX_FIL];
397 }
398
399 /**
400 * can_rx_register - subscribe CAN frames from a specific interface
401 * @dev: pointer to netdevice (NULL => subcribe from 'all' CAN devices list)
402 * @can_id: CAN identifier (see description)
403 * @mask: CAN mask (see description)
404 * @func: callback function on filter match
405 * @data: returned parameter for callback function
406 * @ident: string for calling module indentification
407 *
408 * Description:
409 * Invokes the callback function with the received sk_buff and the given
410 * parameter 'data' on a matching receive filter. A filter matches, when
411 *
412 * <received_can_id> & mask == can_id & mask
413 *
414 * The filter can be inverted (CAN_INV_FILTER bit set in can_id) or it can
415 * filter for error frames (CAN_ERR_FLAG bit set in mask).
416 *
417 * The provided pointer to the sk_buff is guaranteed to be valid as long as
418 * the callback function is running. The callback function must *not* free
419 * the given sk_buff while processing it's task. When the given sk_buff is
420 * needed after the end of the callback function it must be cloned inside
421 * the callback function with skb_clone().
422 *
423 * Return:
424 * 0 on success
425 * -ENOMEM on missing cache mem to create subscription entry
426 * -ENODEV unknown device
427 */
can_rx_register(struct net_device * dev,canid_t can_id,canid_t mask,void (* func)(struct sk_buff *,void *),void * data,char * ident)428 int can_rx_register(struct net_device *dev, canid_t can_id, canid_t mask,
429 void (*func)(struct sk_buff *, void *), void *data,
430 char *ident)
431 {
432 struct receiver *r;
433 struct hlist_head *rl;
434 struct dev_rcv_lists *d;
435 int err = 0;
436
437 /* insert new receiver (dev,canid,mask) -> (func,data) */
438
439 r = kmem_cache_alloc(rcv_cache, GFP_KERNEL);
440 if (!r)
441 return -ENOMEM;
442
443 spin_lock(&can_rcvlists_lock);
444
445 d = find_dev_rcv_lists(dev);
446 if (d) {
447 rl = find_rcv_list(&can_id, &mask, d);
448
449 r->can_id = can_id;
450 r->mask = mask;
451 r->matches = 0;
452 r->func = func;
453 r->data = data;
454 r->ident = ident;
455
456 hlist_add_head_rcu(&r->list, rl);
457 d->entries++;
458
459 can_pstats.rcv_entries++;
460 if (can_pstats.rcv_entries_max < can_pstats.rcv_entries)
461 can_pstats.rcv_entries_max = can_pstats.rcv_entries;
462 } else {
463 kmem_cache_free(rcv_cache, r);
464 err = -ENODEV;
465 }
466
467 spin_unlock(&can_rcvlists_lock);
468
469 return err;
470 }
471 EXPORT_SYMBOL(can_rx_register);
472
473 /*
474 * can_rx_delete_device - rcu callback for dev_rcv_lists structure removal
475 */
can_rx_delete_device(struct rcu_head * rp)476 static void can_rx_delete_device(struct rcu_head *rp)
477 {
478 struct dev_rcv_lists *d = container_of(rp, struct dev_rcv_lists, rcu);
479
480 kfree(d);
481 }
482
483 /*
484 * can_rx_delete_receiver - rcu callback for single receiver entry removal
485 */
can_rx_delete_receiver(struct rcu_head * rp)486 static void can_rx_delete_receiver(struct rcu_head *rp)
487 {
488 struct receiver *r = container_of(rp, struct receiver, rcu);
489
490 kmem_cache_free(rcv_cache, r);
491 }
492
493 /**
494 * can_rx_unregister - unsubscribe CAN frames from a specific interface
495 * @dev: pointer to netdevice (NULL => unsubcribe from 'all' CAN devices list)
496 * @can_id: CAN identifier
497 * @mask: CAN mask
498 * @func: callback function on filter match
499 * @data: returned parameter for callback function
500 *
501 * Description:
502 * Removes subscription entry depending on given (subscription) values.
503 */
can_rx_unregister(struct net_device * dev,canid_t can_id,canid_t mask,void (* func)(struct sk_buff *,void *),void * data)504 void can_rx_unregister(struct net_device *dev, canid_t can_id, canid_t mask,
505 void (*func)(struct sk_buff *, void *), void *data)
506 {
507 struct receiver *r = NULL;
508 struct hlist_head *rl;
509 struct hlist_node *next;
510 struct dev_rcv_lists *d;
511
512 spin_lock(&can_rcvlists_lock);
513
514 d = find_dev_rcv_lists(dev);
515 if (!d) {
516 printk(KERN_ERR "BUG: receive list not found for "
517 "dev %s, id %03X, mask %03X\n",
518 DNAME(dev), can_id, mask);
519 goto out;
520 }
521
522 rl = find_rcv_list(&can_id, &mask, d);
523
524 /*
525 * Search the receiver list for the item to delete. This should
526 * exist, since no receiver may be unregistered that hasn't
527 * been registered before.
528 */
529
530 hlist_for_each_entry_rcu(r, next, rl, list) {
531 if (r->can_id == can_id && r->mask == mask
532 && r->func == func && r->data == data)
533 break;
534 }
535
536 /*
537 * Check for bugs in CAN protocol implementations:
538 * If no matching list item was found, the list cursor variable next
539 * will be NULL, while r will point to the last item of the list.
540 */
541
542 if (!next) {
543 printk(KERN_ERR "BUG: receive list entry not found for "
544 "dev %s, id %03X, mask %03X\n",
545 DNAME(dev), can_id, mask);
546 r = NULL;
547 d = NULL;
548 goto out;
549 }
550
551 hlist_del_rcu(&r->list);
552 d->entries--;
553
554 if (can_pstats.rcv_entries > 0)
555 can_pstats.rcv_entries--;
556
557 /* remove device structure requested by NETDEV_UNREGISTER */
558 if (d->remove_on_zero_entries && !d->entries)
559 hlist_del_rcu(&d->list);
560 else
561 d = NULL;
562
563 out:
564 spin_unlock(&can_rcvlists_lock);
565
566 /* schedule the receiver item for deletion */
567 if (r)
568 call_rcu(&r->rcu, can_rx_delete_receiver);
569
570 /* schedule the device structure for deletion */
571 if (d)
572 call_rcu(&d->rcu, can_rx_delete_device);
573 }
574 EXPORT_SYMBOL(can_rx_unregister);
575
deliver(struct sk_buff * skb,struct receiver * r)576 static inline void deliver(struct sk_buff *skb, struct receiver *r)
577 {
578 r->func(skb, r->data);
579 r->matches++;
580 }
581
can_rcv_filter(struct dev_rcv_lists * d,struct sk_buff * skb)582 static int can_rcv_filter(struct dev_rcv_lists *d, struct sk_buff *skb)
583 {
584 struct receiver *r;
585 struct hlist_node *n;
586 int matches = 0;
587 struct can_frame *cf = (struct can_frame *)skb->data;
588 canid_t can_id = cf->can_id;
589
590 if (d->entries == 0)
591 return 0;
592
593 if (can_id & CAN_ERR_FLAG) {
594 /* check for error frame entries only */
595 hlist_for_each_entry_rcu(r, n, &d->rx[RX_ERR], list) {
596 if (can_id & r->mask) {
597 deliver(skb, r);
598 matches++;
599 }
600 }
601 return matches;
602 }
603
604 /* check for unfiltered entries */
605 hlist_for_each_entry_rcu(r, n, &d->rx[RX_ALL], list) {
606 deliver(skb, r);
607 matches++;
608 }
609
610 /* check for can_id/mask entries */
611 hlist_for_each_entry_rcu(r, n, &d->rx[RX_FIL], list) {
612 if ((can_id & r->mask) == r->can_id) {
613 deliver(skb, r);
614 matches++;
615 }
616 }
617
618 /* check for inverted can_id/mask entries */
619 hlist_for_each_entry_rcu(r, n, &d->rx[RX_INV], list) {
620 if ((can_id & r->mask) != r->can_id) {
621 deliver(skb, r);
622 matches++;
623 }
624 }
625
626 /* check filterlists for single non-RTR can_ids */
627 if (can_id & CAN_RTR_FLAG)
628 return matches;
629
630 if (can_id & CAN_EFF_FLAG) {
631 hlist_for_each_entry_rcu(r, n, &d->rx[RX_EFF], list) {
632 if (r->can_id == can_id) {
633 deliver(skb, r);
634 matches++;
635 }
636 }
637 } else {
638 can_id &= CAN_SFF_MASK;
639 hlist_for_each_entry_rcu(r, n, &d->rx_sff[can_id], list) {
640 deliver(skb, r);
641 matches++;
642 }
643 }
644
645 return matches;
646 }
647
can_rcv(struct sk_buff * skb,struct net_device * dev,struct packet_type * pt,struct net_device * orig_dev)648 static int can_rcv(struct sk_buff *skb, struct net_device *dev,
649 struct packet_type *pt, struct net_device *orig_dev)
650 {
651 struct dev_rcv_lists *d;
652 struct can_frame *cf = (struct can_frame *)skb->data;
653 int matches;
654
655 if (dev->type != ARPHRD_CAN || !net_eq(dev_net(dev), &init_net)) {
656 kfree_skb(skb);
657 return 0;
658 }
659
660 BUG_ON(skb->len != sizeof(struct can_frame) || cf->can_dlc > 8);
661
662 /* update statistics */
663 can_stats.rx_frames++;
664 can_stats.rx_frames_delta++;
665
666 rcu_read_lock();
667
668 /* deliver the packet to sockets listening on all devices */
669 matches = can_rcv_filter(&can_rx_alldev_list, skb);
670
671 /* find receive list for this device */
672 d = find_dev_rcv_lists(dev);
673 if (d)
674 matches += can_rcv_filter(d, skb);
675
676 rcu_read_unlock();
677
678 /* free the skbuff allocated by the netdevice driver */
679 kfree_skb(skb);
680
681 if (matches > 0) {
682 can_stats.matches++;
683 can_stats.matches_delta++;
684 }
685
686 return 0;
687 }
688
689 /*
690 * af_can protocol functions
691 */
692
693 /**
694 * can_proto_register - register CAN transport protocol
695 * @cp: pointer to CAN protocol structure
696 *
697 * Return:
698 * 0 on success
699 * -EINVAL invalid (out of range) protocol number
700 * -EBUSY protocol already in use
701 * -ENOBUF if proto_register() fails
702 */
can_proto_register(struct can_proto * cp)703 int can_proto_register(struct can_proto *cp)
704 {
705 int proto = cp->protocol;
706 int err = 0;
707
708 if (proto < 0 || proto >= CAN_NPROTO) {
709 printk(KERN_ERR "can: protocol number %d out of range\n",
710 proto);
711 return -EINVAL;
712 }
713
714 err = proto_register(cp->prot, 0);
715 if (err < 0)
716 return err;
717
718 spin_lock(&proto_tab_lock);
719 if (proto_tab[proto]) {
720 printk(KERN_ERR "can: protocol %d already registered\n",
721 proto);
722 err = -EBUSY;
723 } else {
724 proto_tab[proto] = cp;
725
726 /* use generic ioctl function if not defined by module */
727 if (!cp->ops->ioctl)
728 cp->ops->ioctl = can_ioctl;
729 }
730 spin_unlock(&proto_tab_lock);
731
732 if (err < 0)
733 proto_unregister(cp->prot);
734
735 return err;
736 }
737 EXPORT_SYMBOL(can_proto_register);
738
739 /**
740 * can_proto_unregister - unregister CAN transport protocol
741 * @cp: pointer to CAN protocol structure
742 */
can_proto_unregister(struct can_proto * cp)743 void can_proto_unregister(struct can_proto *cp)
744 {
745 int proto = cp->protocol;
746
747 spin_lock(&proto_tab_lock);
748 if (!proto_tab[proto]) {
749 printk(KERN_ERR "BUG: can: protocol %d is not registered\n",
750 proto);
751 }
752 proto_tab[proto] = NULL;
753 spin_unlock(&proto_tab_lock);
754
755 proto_unregister(cp->prot);
756 }
757 EXPORT_SYMBOL(can_proto_unregister);
758
759 /*
760 * af_can notifier to create/remove CAN netdevice specific structs
761 */
can_notifier(struct notifier_block * nb,unsigned long msg,void * data)762 static int can_notifier(struct notifier_block *nb, unsigned long msg,
763 void *data)
764 {
765 struct net_device *dev = (struct net_device *)data;
766 struct dev_rcv_lists *d;
767
768 if (!net_eq(dev_net(dev), &init_net))
769 return NOTIFY_DONE;
770
771 if (dev->type != ARPHRD_CAN)
772 return NOTIFY_DONE;
773
774 switch (msg) {
775
776 case NETDEV_REGISTER:
777
778 /*
779 * create new dev_rcv_lists for this device
780 *
781 * N.B. zeroing the struct is the correct initialization
782 * for the embedded hlist_head structs.
783 * Another list type, e.g. list_head, would require
784 * explicit initialization.
785 */
786
787 d = kzalloc(sizeof(*d), GFP_KERNEL);
788 if (!d) {
789 printk(KERN_ERR
790 "can: allocation of receive list failed\n");
791 return NOTIFY_DONE;
792 }
793 d->dev = dev;
794
795 spin_lock(&can_rcvlists_lock);
796 hlist_add_head_rcu(&d->list, &can_rx_dev_list);
797 spin_unlock(&can_rcvlists_lock);
798
799 break;
800
801 case NETDEV_UNREGISTER:
802 spin_lock(&can_rcvlists_lock);
803
804 d = find_dev_rcv_lists(dev);
805 if (d) {
806 if (d->entries) {
807 d->remove_on_zero_entries = 1;
808 d = NULL;
809 } else
810 hlist_del_rcu(&d->list);
811 } else
812 printk(KERN_ERR "can: notifier: receive list not "
813 "found for dev %s\n", dev->name);
814
815 spin_unlock(&can_rcvlists_lock);
816
817 if (d)
818 call_rcu(&d->rcu, can_rx_delete_device);
819
820 break;
821 }
822
823 return NOTIFY_DONE;
824 }
825
826 /*
827 * af_can module init/exit functions
828 */
829
830 static struct packet_type can_packet __read_mostly = {
831 .type = __constant_htons(ETH_P_CAN),
832 .dev = NULL,
833 .func = can_rcv,
834 };
835
836 static struct net_proto_family can_family_ops __read_mostly = {
837 .family = PF_CAN,
838 .create = can_create,
839 .owner = THIS_MODULE,
840 };
841
842 /* notifier block for netdevice event */
843 static struct notifier_block can_netdev_notifier __read_mostly = {
844 .notifier_call = can_notifier,
845 };
846
can_init(void)847 static __init int can_init(void)
848 {
849 printk(banner);
850
851 rcv_cache = kmem_cache_create("can_receiver", sizeof(struct receiver),
852 0, 0, NULL);
853 if (!rcv_cache)
854 return -ENOMEM;
855
856 /*
857 * Insert can_rx_alldev_list for reception on all devices.
858 * This struct is zero initialized which is correct for the
859 * embedded hlist heads, the dev pointer, and the entries counter.
860 */
861
862 spin_lock(&can_rcvlists_lock);
863 hlist_add_head_rcu(&can_rx_alldev_list.list, &can_rx_dev_list);
864 spin_unlock(&can_rcvlists_lock);
865
866 if (stats_timer) {
867 /* the statistics are updated every second (timer triggered) */
868 setup_timer(&can_stattimer, can_stat_update, 0);
869 mod_timer(&can_stattimer, round_jiffies(jiffies + HZ));
870 } else
871 can_stattimer.function = NULL;
872
873 can_init_proc();
874
875 /* protocol register */
876 sock_register(&can_family_ops);
877 register_netdevice_notifier(&can_netdev_notifier);
878 dev_add_pack(&can_packet);
879
880 return 0;
881 }
882
can_exit(void)883 static __exit void can_exit(void)
884 {
885 struct dev_rcv_lists *d;
886 struct hlist_node *n, *next;
887
888 if (stats_timer)
889 del_timer(&can_stattimer);
890
891 can_remove_proc();
892
893 /* protocol unregister */
894 dev_remove_pack(&can_packet);
895 unregister_netdevice_notifier(&can_netdev_notifier);
896 sock_unregister(PF_CAN);
897
898 /* remove can_rx_dev_list */
899 spin_lock(&can_rcvlists_lock);
900 hlist_del(&can_rx_alldev_list.list);
901 hlist_for_each_entry_safe(d, n, next, &can_rx_dev_list, list) {
902 hlist_del(&d->list);
903 kfree(d);
904 }
905 spin_unlock(&can_rcvlists_lock);
906
907 kmem_cache_destroy(rcv_cache);
908 }
909
910 module_init(can_init);
911 module_exit(can_exit);
912