/*
 * 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)");

HLIST_HEAD(can_rx_dev_list);
static 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_SPINLOCK(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
 */

static 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;
        }
}

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

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

        sock->state = SS_UNCONNECTED;

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

        if (net != &init_net)
                return -EAFNOSUPPORT;

#ifdef CONFIG_KMOD
        /* try to load protocol module, when CONFIG_KMOD is defined */
        if (!proto_tab[protocol]) {
                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);
        }
#endif

        spin_lock(&proto_tab_lock);
        cp = proto_tab[protocol];
        if (cp && !try_module_get(cp->prot->owner))
                cp = NULL;
        spin_unlock(&proto_tab_lock);

        /* check for available protocol and correct usage */

        if (!cp)
                return -EPROTONOSUPPORT;

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

        if (cp->capability >= 0 && !capable(cp->capability)) {
                err = -EPERM;
                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!)
 *
 * 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) {
                if (newskb)
                        kfree_skb(newskb);
                return err;
        }

        if (newskb)
                netif_rx(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)
{
        struct dev_rcv_lists *d = NULL;
        struct hlist_node *n;

        /*
         * find receive list for this device
         *
         * The hlist_for_each_entry*() macros curse through the list
         * using the pointer variable n and set d to the containing
         * struct in each list iteration.  Therefore, after list
         * iteration, d is unmodified when the list is empty, and it
         * points to last list element, when the list is non-empty
         * but no match in the loop body is found.  I.e. d is *not*
         * NULL when no match is found.  We can, however, use the
         * cursor variable n to decide if a match was found.
         */

        hlist_for_each_entry_rcu(d, n, &can_rx_dev_list, list) {
                if (d->dev == dev)
                        break;
        }

        return n ? d : NULL;
}

/**
 * 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).
 *
 * 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) */

        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_device - rcu callback for dev_rcv_lists structure removal
 */
static void can_rx_delete_device(struct rcu_head *rp)
{
        struct dev_rcv_lists *d = container_of(rp, struct dev_rcv_lists, rcu);

        kfree(d);
}

/*
 * 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;

        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;
                d = 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)
                hlist_del_rcu(&d->list);
        else
                d = NULL;

 out:
        spin_unlock(&can_rcvlists_lock);

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

        /* schedule the device structure for deletion */
        if (d)
                call_rcu(&d->rcu, can_rx_delete_device);
}
EXPORT_SYMBOL(can_rx_unregister);

static inline void deliver(struct sk_buff *skb, struct receiver *r)
{
        struct sk_buff *clone = skb_clone(skb, GFP_ATOMIC);

        if (clone) {
                clone->sk = skb->sk;
                r->func(clone, 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 (dev->type != ARPHRD_CAN || !net_eq(dev_net(dev), &init_net)) {
                kfree_skb(skb);
                return 0;
        }

        BUG_ON(skb->len != sizeof(struct can_frame) || cf->can_dlc > 8);

        /* 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();

        /* free the skbuff allocated by the netdevice driver */
        kfree_skb(skb);

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

        return 0;
}

/*
 * 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;

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

                /* use generic ioctl function if not defined by module */
                if (!cp->ops->ioctl)
                        cp->ops->ioctl = can_ioctl;
        }
        spin_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;

        spin_lock(&proto_tab_lock);
        if (!proto_tab[proto]) {
                printk(KERN_ERR "BUG: can: protocol %d is not registered\n",
                       proto);
        }
        proto_tab[proto] = NULL;
        spin_unlock(&proto_tab_lock);

        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
                 *
                 * N.B. zeroing the struct is the correct initialization
                 * for the embedded hlist_head structs.
                 * Another list type, e.g. list_head, would require
                 * explicit initialization.
                 */

                d = kzalloc(sizeof(*d), GFP_KERNEL);
                if (!d) {
                        printk(KERN_ERR
                               "can: allocation of receive list failed\n");
                        return NOTIFY_DONE;
                }
                d->dev = dev;

                spin_lock(&can_rcvlists_lock);
                hlist_add_head_rcu(&d->list, &can_rx_dev_list);
                spin_unlock(&can_rcvlists_lock);

                break;

        case NETDEV_UNREGISTER:
                spin_lock(&can_rcvlists_lock);

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

                spin_unlock(&can_rcvlists_lock);

                if (d)
                        call_rcu(&d->rcu, can_rx_delete_device);

                break;
        }

        return NOTIFY_DONE;
}

/*
 * af_can module init/exit functions
 */

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

static struct net_proto_family can_family_ops __read_mostly = {
        .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);

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

        /*
         * Insert can_rx_alldev_list for reception on all devices.
         * This struct is zero initialized which is correct for the
         * embedded hlist heads, the dev pointer, and the entries counter.
         */

        spin_lock(&can_rcvlists_lock);
        hlist_add_head_rcu(&can_rx_alldev_list.list, &can_rx_dev_list);
        spin_unlock(&can_rcvlists_lock);

        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 dev_rcv_lists *d;
        struct hlist_node *n, *next;

        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 can_rx_dev_list */
        spin_lock(&can_rcvlists_lock);
        hlist_del(&can_rx_alldev_list.list);
        hlist_for_each_entry_safe(d, n, next, &can_rx_dev_list, list) {
                hlist_del(&d->list);
                kfree(d);
        }
        spin_unlock(&can_rcvlists_lock);

        kmem_cache_destroy(rcv_cache);
}

module_init(can_init);
module_exit(can_exit);