af_can.c 23.2 KB
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
/*
 * 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.
 *
 */

#include <linux/module.h>
#include <linux/stddef.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 <linux/can/skb.h>
#include <linux/ratelimit.h>
#include <net/net_namespace.h>
#include <net/sock.h>

#include "af_can.h"

static __initconst 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 const 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 const struct can_proto *can_get_proto(int protocol)
{
	const 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 inline void can_put_proto(const struct can_proto *cp)
{
	module_put(cp->prot->owner);
}

static int can_create(struct net *net, struct socket *sock, int protocol,
		      int kern)
{
	struct sock *sk;
	const 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_get_proto(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_ratelimited(KERN_ERR "can: request_module "
			       "(can-proto-%d) failed.\n", protocol);

		cp = can_get_proto(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:
	can_put_proto(cp);
	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
 *  -EMSGSIZE CAN frame size is bigger than CAN interface MTU
 *  -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 canfd_frame *cfd = (struct canfd_frame *)skb->data;
	int err = -EINVAL;

	if (skb->len == CAN_MTU) {
		skb->protocol = htons(ETH_P_CAN);
		if (unlikely(cfd->len > CAN_MAX_DLEN))
			goto inval_skb;
	} else if (skb->len == CANFD_MTU) {
		skb->protocol = htons(ETH_P_CANFD);
		if (unlikely(cfd->len > CANFD_MAX_DLEN))
			goto inval_skb;
	} else
		goto inval_skb;

	/*
	 * Make sure the CAN frame can pass the selected CAN netdevice.
	 * As structs can_frame and canfd_frame are similar, we can provide
	 * CAN FD frames to legacy CAN drivers as long as the length is <= 8
	 */
	if (unlikely(skb->len > skb->dev->mtu && cfd->len > CAN_MAX_DLEN)) {
		err = -EMSGSIZE;
		goto inval_skb;
	}

	if (unlikely(skb->dev->type != ARPHRD_CAN)) {
		err = -EPERM;
		goto inval_skb;
	}

	if (unlikely(!(skb->dev->flags & IFF_UP))) {
		err = -ENETDOWN;
		goto inval_skb;
	}

	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;
			}

			can_skb_set_owner(newskb, 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;

inval_skb:
	kfree_skb(skb);
	return err;
}
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 messages (CAN_ERR_FLAG bit set in mask). For error msg
 *  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 message 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 identification
 *
 * 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 message 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 dev_rcv_lists *d;

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

	spin_lock(&can_rcvlists_lock);

	d = find_dev_rcv_lists(dev);
	if (!d) {
		pr_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, 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 using af_can.c:
	 * 'r' will be NULL if no matching list item was found for removal.
	 */

	if (!r) {
		WARN(1, "BUG: receive list entry not found for dev %s, "
		     "id %03X, mask %03X\n", DNAME(dev), can_id, mask);
		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;
	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 message frame entries only */
		hlist_for_each_entry_rcu(r, &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, &d->rx[RX_ALL], list) {
		deliver(skb, r);
		matches++;
	}

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

	return matches;
}

static void can_receive(struct sk_buff *skb, struct net_device *dev)
{
	struct dev_rcv_lists *d;
	int matches;

	/* 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++;
	}
}

static int can_rcv(struct sk_buff *skb, struct net_device *dev,
		   struct packet_type *pt, struct net_device *orig_dev)
{
	struct canfd_frame *cfd = (struct canfd_frame *)skb->data;

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

	if (WARN_ONCE(dev->type != ARPHRD_CAN ||
		      skb->len != CAN_MTU ||
		      cfd->len > CAN_MAX_DLEN,
		      "PF_CAN: dropped non conform CAN skbuf: "
		      "dev type %d, len %d, datalen %d\n",
		      dev->type, skb->len, cfd->len))
		goto drop;

	can_receive(skb, dev);
	return NET_RX_SUCCESS;

drop:
	kfree_skb(skb);
	return NET_RX_DROP;
}

static int canfd_rcv(struct sk_buff *skb, struct net_device *dev,
		   struct packet_type *pt, struct net_device *orig_dev)
{
	struct canfd_frame *cfd = (struct canfd_frame *)skb->data;

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

	if (WARN_ONCE(dev->type != ARPHRD_CAN ||
		      skb->len != CANFD_MTU ||
		      cfd->len > CANFD_MAX_DLEN,
		      "PF_CAN: dropped non conform CAN FD skbuf: "
		      "dev type %d, len %d, datalen %d\n",
		      dev->type, skb->len, cfd->len))
		goto drop;

	can_receive(skb, dev);
	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(const struct can_proto *cp)
{
	int proto = cp->protocol;
	int err = 0;

	if (proto < 0 || proto >= CAN_NPROTO) {
		pr_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]) {
		pr_err("can: protocol %d already registered\n", proto);
		err = -EBUSY;
	} else
		RCU_INIT_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(const struct can_proto *cp)
{
	int proto = cp->protocol;

	mutex_lock(&proto_tab_lock);
	BUG_ON(proto_tab[proto] != cp);
	RCU_INIT_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 *ptr)
{
	struct net_device *dev = netdev_notifier_info_to_dev(ptr);
	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)
			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
			pr_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),
	.func = can_rcv,
};

static struct packet_type canfd_packet __read_mostly = {
	.type = cpu_to_be16(ETH_P_CANFD),
	.func = canfd_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)
{
	/* check for correct padding to be able to use the structs similarly */
	BUILD_BUG_ON(offsetof(struct can_frame, can_dlc) !=
		     offsetof(struct canfd_frame, len) ||
		     offsetof(struct can_frame, data) !=
		     offsetof(struct canfd_frame, data));

	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);
	dev_add_pack(&canfd_packet);

	return 0;
}

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

	if (stats_timer)
		del_timer_sync(&can_stattimer);

	can_remove_proc();

	/* protocol unregister */
	dev_remove_pack(&canfd_packet);
	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);