/*
   * 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/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/ratelimit.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 ")
  ";
  
  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.
  ", 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

   *  -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
  ",
  		       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
  ",
  		       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
  ",
  		      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(const 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
  ",
  		       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
  ",
  		       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 *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
  ");
  			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
  ", 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_sync(&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);