Linux 2.6.19-rc6

[cris-mirror.git] / net / atm / br2684.c

/*
Experimental ethernet netdevice using ATM AAL5 as underlying carrier
(RFC1483 obsoleted by RFC2684) for Linux 2.4
Author: Marcell GAL, 2000, XDSL Ltd, Hungary
*/

#include <linux/module.h>
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/list.h>
#include <linux/netdevice.h>
#include <linux/skbuff.h>
#include <linux/etherdevice.h>
#include <linux/rtnetlink.h>
#include <linux/ip.h>
#include <asm/uaccess.h>
#include <net/arp.h>
#include <linux/atm.h>
#include <linux/atmdev.h>
#include <linux/capability.h>
#include <linux/seq_file.h>

#include <linux/atmbr2684.h>

#include "common.h"
#include "ipcommon.h"

/*
 * Define this to use a version of the code which interacts with the higher
 * layers in a more intellegent way, by always reserving enough space for
 * our header at the begining of the packet.  However, there may still be
 * some problems with programs like tcpdump.  In 2.5 we'll sort out what
 * we need to do to get this perfect.  For now we just will copy the packet
 * if we need space for the header
 */
/* #define FASTER_VERSION */

#ifdef DEBUG
#define DPRINTK(format, args...) printk(KERN_DEBUG "br2684: " format, ##args)
#else
#define DPRINTK(format, args...)
#endif

#ifdef SKB_DEBUG
static void skb_debug(const struct sk_buff *skb)
{
#define NUM2PRINT 50
        char buf[NUM2PRINT * 3 + 1];    /* 3 chars per byte */
        int i = 0;
        for (i = 0; i < skb->len && i < NUM2PRINT; i++) {
                sprintf(buf + i * 3, "%2.2x ", 0xff & skb->data[i]);
        }
        printk(KERN_DEBUG "br2684: skb: %s\n", buf);
}
#else
#define skb_debug(skb)  do {} while (0)
#endif

static unsigned char llc_oui_pid_pad[] =
    { 0xAA, 0xAA, 0x03, 0x00, 0x80, 0xC2, 0x00, 0x07, 0x00, 0x00 };
#define PADLEN  (2)

enum br2684_encaps {
        e_vc  = BR2684_ENCAPS_VC,
        e_llc = BR2684_ENCAPS_LLC,
};

struct br2684_vcc {
        struct atm_vcc  *atmvcc;
        struct net_device *device;
        /* keep old push,pop functions for chaining */
        void (*old_push)(struct atm_vcc *vcc,struct sk_buff *skb);
        /* void (*old_pop)(struct atm_vcc *vcc,struct sk_buff *skb); */
        enum br2684_encaps encaps;
        struct list_head brvccs;
#ifdef CONFIG_ATM_BR2684_IPFILTER
        struct br2684_filter filter;
#endif /* CONFIG_ATM_BR2684_IPFILTER */
#ifndef FASTER_VERSION
        unsigned copies_needed, copies_failed;
#endif /* FASTER_VERSION */
};

struct br2684_dev {
        struct net_device *net_dev;
        struct list_head br2684_devs;
        int number;
        struct list_head brvccs; /* one device <=> one vcc (before xmas) */
        struct net_device_stats stats;
        int mac_was_set;
};

/*
 * This lock should be held for writing any time the list of devices or
 * their attached vcc's could be altered.  It should be held for reading
 * any time these are being queried.  Note that we sometimes need to
 * do read-locking under interrupt context, so write locking must block
 * the current CPU's interrupts
 */
static DEFINE_RWLOCK(devs_lock);

static LIST_HEAD(br2684_devs);

static inline struct br2684_dev *BRPRIV(const struct net_device *net_dev)
{
        return (struct br2684_dev *) net_dev->priv;
}

static inline struct net_device *list_entry_brdev(const struct list_head *le)
{
        return list_entry(le, struct br2684_dev, br2684_devs)->net_dev;
}

static inline struct br2684_vcc *BR2684_VCC(const struct atm_vcc *atmvcc)
{
        return (struct br2684_vcc *) (atmvcc->user_back);
}

static inline struct br2684_vcc *list_entry_brvcc(const struct list_head *le)
{
        return list_entry(le, struct br2684_vcc, brvccs);
}

/* Caller should hold read_lock(&devs_lock) */
static struct net_device *br2684_find_dev(const struct br2684_if_spec *s)
{
        struct list_head *lh;
        struct net_device *net_dev;
        switch (s->method) {
        case BR2684_FIND_BYNUM:
                list_for_each(lh, &br2684_devs) {
                        net_dev = list_entry_brdev(lh);
                        if (BRPRIV(net_dev)->number == s->spec.devnum)
                                return net_dev;
                }
                break;
        case BR2684_FIND_BYIFNAME:
                list_for_each(lh, &br2684_devs) {
                        net_dev = list_entry_brdev(lh);
                        if (!strncmp(net_dev->name, s->spec.ifname, IFNAMSIZ))
                                return net_dev;
                }
                break;
        }
        return NULL;
}

/*
 * Send a packet out a particular vcc.  Not to useful right now, but paves
 * the way for multiple vcc's per itf.  Returns true if we can send,
 * otherwise false
 */
static int br2684_xmit_vcc(struct sk_buff *skb, struct br2684_dev *brdev,
        struct br2684_vcc *brvcc)
{
        struct atm_vcc *atmvcc;
#ifdef FASTER_VERSION
        if (brvcc->encaps == e_llc)
                memcpy(skb_push(skb, 8), llc_oui_pid_pad, 8);
        /* last 2 bytes of llc_oui_pid_pad are managed by header routines;
           yes, you got it: 8 + 2 = sizeof(llc_oui_pid_pad)
         */
#else
        int minheadroom = (brvcc->encaps == e_llc) ? 10 : 2;
        if (skb_headroom(skb) < minheadroom) {
                struct sk_buff *skb2 = skb_realloc_headroom(skb, minheadroom);
                brvcc->copies_needed++;
                dev_kfree_skb(skb);
                if (skb2 == NULL) {
                        brvcc->copies_failed++;
                        return 0;
                }
                skb = skb2;
        }
        skb_push(skb, minheadroom);
        if (brvcc->encaps == e_llc)
                memcpy(skb->data, llc_oui_pid_pad, 10);
        else
                memset(skb->data, 0, 2);
#endif /* FASTER_VERSION */
        skb_debug(skb);

        ATM_SKB(skb)->vcc = atmvcc = brvcc->atmvcc;
        DPRINTK("atm_skb(%p)->vcc(%p)->dev(%p)\n", skb, atmvcc, atmvcc->dev);
        if (!atm_may_send(atmvcc, skb->truesize)) {
                /* we free this here for now, because we cannot know in a higher 
                        layer whether the skb point it supplied wasn't freed yet.
                        now, it always is.
                */
                dev_kfree_skb(skb);
                return 0;
                }
        atomic_add(skb->truesize, &sk_atm(atmvcc)->sk_wmem_alloc);
        ATM_SKB(skb)->atm_options = atmvcc->atm_options;
        brdev->stats.tx_packets++;
        brdev->stats.tx_bytes += skb->len;
        atmvcc->send(atmvcc, skb);
        return 1;
}

static inline struct br2684_vcc *pick_outgoing_vcc(struct sk_buff *skb,
        struct br2684_dev *brdev)
{
        return list_empty(&brdev->brvccs) ? NULL :
            list_entry_brvcc(brdev->brvccs.next); /* 1 vcc/dev right now */
}

static int br2684_start_xmit(struct sk_buff *skb, struct net_device *dev)
{
        struct br2684_dev *brdev = BRPRIV(dev);
        struct br2684_vcc *brvcc;

        DPRINTK("br2684_start_xmit, skb->dst=%p\n", skb->dst);
        read_lock(&devs_lock);
        brvcc = pick_outgoing_vcc(skb, brdev);
        if (brvcc == NULL) {
                DPRINTK("no vcc attached to dev %s\n", dev->name);
                brdev->stats.tx_errors++;
                brdev->stats.tx_carrier_errors++;
                /* netif_stop_queue(dev); */
                dev_kfree_skb(skb);
                read_unlock(&devs_lock);
                return 0;
        }
        if (!br2684_xmit_vcc(skb, brdev, brvcc)) {
                /*
                 * We should probably use netif_*_queue() here, but that
                 * involves added complication.  We need to walk before
                 * we can run
                 */
                /* don't free here! this pointer might be no longer valid!
                dev_kfree_skb(skb);
                */
                brdev->stats.tx_errors++;
                brdev->stats.tx_fifo_errors++;
        }
        read_unlock(&devs_lock);
        return 0;
}

static struct net_device_stats *br2684_get_stats(struct net_device *dev)
{
        DPRINTK("br2684_get_stats\n");
        return &BRPRIV(dev)->stats;
}

#ifdef FASTER_VERSION
/*
 * These mirror eth_header and eth_header_cache.  They are not usually
 * exported for use in modules, so we grab them from net_device
 * after ether_setup() is done with it.  Bit of a hack.
 */
static int (*my_eth_header)(struct sk_buff *, struct net_device *,
        unsigned short, void *, void *, unsigned);
static int (*my_eth_header_cache)(struct neighbour *, struct hh_cache *);

static int
br2684_header(struct sk_buff *skb, struct net_device *dev,
              unsigned short type, void *daddr, void *saddr, unsigned len)
{
        u16 *pad_before_eth;
        int t = my_eth_header(skb, dev, type, daddr, saddr, len);
        if (t > 0) {
                pad_before_eth = (u16 *) skb_push(skb, 2);
                *pad_before_eth = 0;
                return dev->hard_header_len;    /* or return 16; ? */
        } else
                return t;
}

static int
br2684_header_cache(struct neighbour *neigh, struct hh_cache *hh)
{
/* hh_data is 16 bytes long. if encaps is ether-llc we need 24, so
xmit will add the additional header part in that case */
        u16 *pad_before_eth = (u16 *)(hh->hh_data);
        int t = my_eth_header_cache(neigh, hh);
        DPRINTK("br2684_header_cache, neigh=%p, hh_cache=%p\n", neigh, hh);
        if (t < 0)
                return t;
        else {
                *pad_before_eth = 0;
                hh->hh_len = PADLEN + ETH_HLEN;
        }
        return 0;
}

/*
 * This is similar to eth_type_trans, which cannot be used because of
 * our dev->hard_header_len
 */
static inline __be16 br_type_trans(struct sk_buff *skb, struct net_device *dev)
{
        struct ethhdr *eth;
        unsigned char *rawp;
        eth = eth_hdr(skb);

        if (is_multicast_ether_addr(eth->h_dest)) {
                if (!compare_ether_addr(eth->h_dest, dev->broadcast))
                        skb->pkt_type = PACKET_BROADCAST;
                else
                        skb->pkt_type = PACKET_MULTICAST;
        }

        else if (compare_ether_addr(eth->h_dest, dev->dev_addr))
                skb->pkt_type = PACKET_OTHERHOST;

        if (ntohs(eth->h_proto) >= 1536)
                return eth->h_proto;

        rawp = skb->data;

        /*
         * This is a magic hack to spot IPX packets. Older Novell breaks
         * the protocol design and runs IPX over 802.3 without an 802.2 LLC
         * layer. We look for FFFF which isn't a used 802.2 SSAP/DSAP. This
         * won't work for fault tolerant netware but does for the rest.
         */
        if (*(unsigned short *) rawp == 0xFFFF)
                return htons(ETH_P_802_3);

        /*
         * Real 802.2 LLC
         */
        return htons(ETH_P_802_2);
}
#endif /* FASTER_VERSION */

/*
 * We remember when the MAC gets set, so we don't override it later with
 * the ESI of the ATM card of the first VC
 */
static int (*my_eth_mac_addr)(struct net_device *, void *);
static int br2684_mac_addr(struct net_device *dev, void *p)
{
        int err = my_eth_mac_addr(dev, p);
        if (!err)
                BRPRIV(dev)->mac_was_set = 1;
        return err;
}

#ifdef CONFIG_ATM_BR2684_IPFILTER
/* this IOCTL is experimental. */
static int br2684_setfilt(struct atm_vcc *atmvcc, void __user *arg)
{
        struct br2684_vcc *brvcc;
        struct br2684_filter_set fs;

        if (copy_from_user(&fs, arg, sizeof fs))
                return -EFAULT;
        if (fs.ifspec.method != BR2684_FIND_BYNOTHING) {
                /*
                 * This is really a per-vcc thing, but we can also search
                 * by device
                 */
                struct br2684_dev *brdev;
                read_lock(&devs_lock);
                brdev = BRPRIV(br2684_find_dev(&fs.ifspec));
                if (brdev == NULL || list_empty(&brdev->brvccs) ||
                    brdev->brvccs.next != brdev->brvccs.prev)  /* >1 VCC */
                        brvcc = NULL;
                else
                        brvcc = list_entry_brvcc(brdev->brvccs.next);
                read_unlock(&devs_lock);
                if (brvcc == NULL)
                        return -ESRCH;
        } else
                brvcc = BR2684_VCC(atmvcc);
        memcpy(&brvcc->filter, &fs.filter, sizeof(brvcc->filter));
        return 0;
}

/* Returns 1 if packet should be dropped */
static inline int
packet_fails_filter(u16 type, struct br2684_vcc *brvcc, struct sk_buff *skb)
{
        if (brvcc->filter.netmask == 0)
                return 0;                       /* no filter in place */
        if (type == __constant_htons(ETH_P_IP) &&
            (((struct iphdr *) (skb->data))->daddr & brvcc->filter.
             netmask) == brvcc->filter.prefix)
                return 0;
        if (type == __constant_htons(ETH_P_ARP))
                return 0;
        /* TODO: we should probably filter ARPs too.. don't want to have
         *   them returning values that don't make sense, or is that ok?
         */
        return 1;               /* drop */
}
#endif /* CONFIG_ATM_BR2684_IPFILTER */

static void br2684_close_vcc(struct br2684_vcc *brvcc)
{
        DPRINTK("removing VCC %p from dev %p\n", brvcc, brvcc->device);
        write_lock_irq(&devs_lock);
        list_del(&brvcc->brvccs);
        write_unlock_irq(&devs_lock);
        brvcc->atmvcc->user_back = NULL;        /* what about vcc->recvq ??? */
        brvcc->old_push(brvcc->atmvcc, NULL);   /* pass on the bad news */
        kfree(brvcc);
        module_put(THIS_MODULE);
}

/* when AAL5 PDU comes in: */
static void br2684_push(struct atm_vcc *atmvcc, struct sk_buff *skb)
{
        struct br2684_vcc *brvcc = BR2684_VCC(atmvcc);
        struct net_device *net_dev = brvcc->device;
        struct br2684_dev *brdev = BRPRIV(net_dev);
        int plen = sizeof(llc_oui_pid_pad) + ETH_HLEN;

        DPRINTK("br2684_push\n");

        if (unlikely(skb == NULL)) {
                /* skb==NULL means VCC is being destroyed */
                br2684_close_vcc(brvcc);
                if (list_empty(&brdev->brvccs)) {
                        read_lock(&devs_lock);
                        list_del(&brdev->br2684_devs);
                        read_unlock(&devs_lock);
                        unregister_netdev(net_dev);
                        free_netdev(net_dev);
                }
                return;
        }

        skb_debug(skb);
        atm_return(atmvcc, skb->truesize);
        DPRINTK("skb from brdev %p\n", brdev);
        if (brvcc->encaps == e_llc) {
                /* let us waste some time for checking the encapsulation.
                   Note, that only 7 char is checked so frames with a valid FCS
                   are also accepted (but FCS is not checked of course) */
                if (memcmp(skb->data, llc_oui_pid_pad, 7)) {
                        brdev->stats.rx_errors++;
                        dev_kfree_skb(skb);
                        return;
                }

                /* Strip FCS if present */
                if (skb->len > 7 && skb->data[7] == 0x01)
                        __skb_trim(skb, skb->len - 4);
        } else {
                plen = PADLEN + ETH_HLEN;       /* pad, dstmac,srcmac, ethtype */
                /* first 2 chars should be 0 */
                if (*((u16 *) (skb->data)) != 0) {
                        brdev->stats.rx_errors++;
                        dev_kfree_skb(skb);
                        return;
                }
        }
        if (skb->len < plen) {
                brdev->stats.rx_errors++;
                dev_kfree_skb(skb);     /* dev_ not needed? */
                return;
        }

#ifdef FASTER_VERSION
        /* FIXME: tcpdump shows that pointer to mac header is 2 bytes earlier,
           than should be. What else should I set? */
        skb_pull(skb, plen);
        skb->mac.raw = ((char *) (skb->data)) - ETH_HLEN;
        skb->pkt_type = PACKET_HOST;
#ifdef CONFIG_BR2684_FAST_TRANS
        skb->protocol = ((u16 *) skb->data)[-1];
#else                           /* some protocols might require this: */
        skb->protocol = br_type_trans(skb, net_dev);
#endif /* CONFIG_BR2684_FAST_TRANS */
#else
        skb_pull(skb, plen - ETH_HLEN);
        skb->protocol = eth_type_trans(skb, net_dev);
#endif /* FASTER_VERSION */
#ifdef CONFIG_ATM_BR2684_IPFILTER
        if (unlikely(packet_fails_filter(skb->protocol, brvcc, skb))) {
                brdev->stats.rx_dropped++;
                dev_kfree_skb(skb);
                return;
        }
#endif /* CONFIG_ATM_BR2684_IPFILTER */
        skb->dev = net_dev;
        ATM_SKB(skb)->vcc = atmvcc;     /* needed ? */
        DPRINTK("received packet's protocol: %x\n", ntohs(skb->protocol));
        skb_debug(skb);
        if (unlikely(!(net_dev->flags & IFF_UP))) {
                /* sigh, interface is down */
                brdev->stats.rx_dropped++;
                dev_kfree_skb(skb);
                return;
        }
        brdev->stats.rx_packets++;
        brdev->stats.rx_bytes += skb->len;
        memset(ATM_SKB(skb), 0, sizeof(struct atm_skb_data));
        netif_rx(skb);
}

static int br2684_regvcc(struct atm_vcc *atmvcc, void __user *arg)
{
/* assign a vcc to a dev
Note: we do not have explicit unassign, but look at _push()
*/
        int err;
        struct br2684_vcc *brvcc;
        struct sk_buff_head copy;
        struct sk_buff *skb;
        struct br2684_dev *brdev;
        struct net_device *net_dev;
        struct atm_backend_br2684 be;

        if (copy_from_user(&be, arg, sizeof be))
                return -EFAULT;
        brvcc = kzalloc(sizeof(struct br2684_vcc), GFP_KERNEL);
        if (!brvcc)
                return -ENOMEM;
        write_lock_irq(&devs_lock);
        net_dev = br2684_find_dev(&be.ifspec);
        if (net_dev == NULL) {
                printk(KERN_ERR
                    "br2684: tried to attach to non-existant device\n");
                err = -ENXIO;
                goto error;
        }
        brdev = BRPRIV(net_dev);
        if (atmvcc->push == NULL) {
                err = -EBADFD;
                goto error;
        }
        if (!list_empty(&brdev->brvccs)) {
                /* Only 1 VCC/dev right now */
                err = -EEXIST;
                goto error;
        }
        if (be.fcs_in != BR2684_FCSIN_NO || be.fcs_out != BR2684_FCSOUT_NO ||
            be.fcs_auto || be.has_vpiid || be.send_padding || (be.encaps !=
            BR2684_ENCAPS_VC && be.encaps != BR2684_ENCAPS_LLC) ||
            be.min_size != 0) {
                err = -EINVAL;
                goto error;
        }
        DPRINTK("br2684_regvcc vcc=%p, encaps=%d, brvcc=%p\n", atmvcc, be.encaps,
                brvcc);
        if (list_empty(&brdev->brvccs) && !brdev->mac_was_set) {
                unsigned char *esi = atmvcc->dev->esi;
                if (esi[0] | esi[1] | esi[2] | esi[3] | esi[4] | esi[5])
                        memcpy(net_dev->dev_addr, esi, net_dev->addr_len);
                else
                        net_dev->dev_addr[2] = 1;
        }
        list_add(&brvcc->brvccs, &brdev->brvccs);
        write_unlock_irq(&devs_lock);
        brvcc->device = net_dev;
        brvcc->atmvcc = atmvcc;
        atmvcc->user_back = brvcc;
        brvcc->encaps = (enum br2684_encaps) be.encaps;
        brvcc->old_push = atmvcc->push;
        barrier();
        atmvcc->push = br2684_push;
        skb_queue_head_init(&copy);
        skb_migrate(&sk_atm(atmvcc)->sk_receive_queue, &copy);
        while ((skb = skb_dequeue(&copy)) != NULL) {
                BRPRIV(skb->dev)->stats.rx_bytes -= skb->len;
                BRPRIV(skb->dev)->stats.rx_packets--;
                br2684_push(atmvcc, skb);
        }
        __module_get(THIS_MODULE);
        return 0;
    error:
        write_unlock_irq(&devs_lock);
        kfree(brvcc);
        return err;
}

static void br2684_setup(struct net_device *netdev)
{
        struct br2684_dev *brdev = BRPRIV(netdev);

        ether_setup(netdev);
        brdev->net_dev = netdev;

#ifdef FASTER_VERSION
        my_eth_header = netdev->hard_header;
        netdev->hard_header = br2684_header;
        my_eth_header_cache = netdev->hard_header_cache;
        netdev->hard_header_cache = br2684_header_cache;
        netdev->hard_header_len = sizeof(llc_oui_pid_pad) + ETH_HLEN;   /* 10 + 14 */
#endif
        my_eth_mac_addr = netdev->set_mac_address;
        netdev->set_mac_address = br2684_mac_addr;
        netdev->hard_start_xmit = br2684_start_xmit;
        netdev->get_stats = br2684_get_stats;

        INIT_LIST_HEAD(&brdev->brvccs);
}

static int br2684_create(void __user *arg)
{
        int err;
        struct net_device *netdev;
        struct br2684_dev *brdev;
        struct atm_newif_br2684 ni;

        DPRINTK("br2684_create\n");

        if (copy_from_user(&ni, arg, sizeof ni)) {
                return -EFAULT;
        }
        if (ni.media != BR2684_MEDIA_ETHERNET || ni.mtu != 1500) {
                return -EINVAL;
        }

        netdev = alloc_netdev(sizeof(struct br2684_dev),
                              ni.ifname[0] ? ni.ifname : "nas%d",
                              br2684_setup);
        if (!netdev)
                return -ENOMEM;

        brdev = BRPRIV(netdev);

        DPRINTK("registered netdev %s\n", netdev->name);
        /* open, stop, do_ioctl ? */
        err = register_netdev(netdev);
        if (err < 0) {
                printk(KERN_ERR "br2684_create: register_netdev failed\n");
                free_netdev(netdev);
                return err;
        }

        write_lock_irq(&devs_lock);
        brdev->number = list_empty(&br2684_devs) ? 1 :
            BRPRIV(list_entry_brdev(br2684_devs.prev))->number + 1;
        list_add_tail(&brdev->br2684_devs, &br2684_devs);
        write_unlock_irq(&devs_lock);
        return 0;
}

/*
 * This handles ioctls actually performed on our vcc - we must return
 * -ENOIOCTLCMD for any unrecognized ioctl
 */
static int br2684_ioctl(struct socket *sock, unsigned int cmd,
        unsigned long arg)
{
        struct atm_vcc *atmvcc = ATM_SD(sock);
        void __user *argp = (void __user *)arg;

        int err;
        switch(cmd) {
        case ATM_SETBACKEND:
        case ATM_NEWBACKENDIF: {
                atm_backend_t b;
                err = get_user(b, (atm_backend_t __user *) argp);
                if (err)
                        return -EFAULT;
                if (b != ATM_BACKEND_BR2684)
                        return -ENOIOCTLCMD;
                if (!capable(CAP_NET_ADMIN))
                        return -EPERM;
                if (cmd == ATM_SETBACKEND)
                        return br2684_regvcc(atmvcc, argp);
                else
                        return br2684_create(argp);
                }
#ifdef CONFIG_ATM_BR2684_IPFILTER
        case BR2684_SETFILT:
                if (atmvcc->push != br2684_push)
                        return -ENOIOCTLCMD;
                if (!capable(CAP_NET_ADMIN))
                        return -EPERM;
                err = br2684_setfilt(atmvcc, argp);
                return err;
#endif /* CONFIG_ATM_BR2684_IPFILTER */
        }
        return -ENOIOCTLCMD;
}

static struct atm_ioctl br2684_ioctl_ops = {
        .owner  = THIS_MODULE,
        .ioctl  = br2684_ioctl,
};


#ifdef CONFIG_PROC_FS
static void *br2684_seq_start(struct seq_file *seq, loff_t *pos)
{
        loff_t offs = 0;
        struct br2684_dev *brd;

        read_lock(&devs_lock);

        list_for_each_entry(brd, &br2684_devs, br2684_devs) {
                if (offs == *pos)
                        return brd;
                ++offs;
        }
        return NULL;
}

static void *br2684_seq_next(struct seq_file *seq, void *v, loff_t *pos)
{
        struct br2684_dev *brd = v;

        ++*pos;

        brd = list_entry(brd->br2684_devs.next, 
                         struct br2684_dev, br2684_devs);
        return (&brd->br2684_devs != &br2684_devs) ? brd : NULL;
}

static void br2684_seq_stop(struct seq_file *seq, void *v)
{
        read_unlock(&devs_lock);
}

static int br2684_seq_show(struct seq_file *seq, void *v)
{
        const struct br2684_dev *brdev = v;
        const struct net_device *net_dev = brdev->net_dev;
        const struct br2684_vcc *brvcc;

        seq_printf(seq, "dev %.16s: num=%d, mac=%02X:%02X:"
                       "%02X:%02X:%02X:%02X (%s)\n", net_dev->name,
                       brdev->number,
                       net_dev->dev_addr[0],
                       net_dev->dev_addr[1],
                       net_dev->dev_addr[2],
                       net_dev->dev_addr[3],
                       net_dev->dev_addr[4],
                       net_dev->dev_addr[5],
                       brdev->mac_was_set ? "set" : "auto");

        list_for_each_entry(brvcc, &brdev->brvccs, brvccs) {
                seq_printf(seq, "  vcc %d.%d.%d: encaps=%s"
#ifndef FASTER_VERSION
                                    ", failed copies %u/%u"
#endif /* FASTER_VERSION */
                                    "\n", brvcc->atmvcc->dev->number,
                                    brvcc->atmvcc->vpi, brvcc->atmvcc->vci,
                                    (brvcc->encaps == e_llc) ? "LLC" : "VC"
#ifndef FASTER_VERSION
                                    , brvcc->copies_failed
                                    , brvcc->copies_needed
#endif /* FASTER_VERSION */
                                    );
#ifdef CONFIG_ATM_BR2684_IPFILTER
#define b1(var, byte)   ((u8 *) &brvcc->filter.var)[byte]
#define bs(var)         b1(var, 0), b1(var, 1), b1(var, 2), b1(var, 3)
                        if (brvcc->filter.netmask != 0)
                                seq_printf(seq, "    filter=%d.%d.%d.%d/"
                                                "%d.%d.%d.%d\n",
                                                bs(prefix), bs(netmask));
#undef bs
#undef b1
#endif /* CONFIG_ATM_BR2684_IPFILTER */
        }
        return 0;
}

static struct seq_operations br2684_seq_ops = {
        .start = br2684_seq_start,
        .next  = br2684_seq_next,
        .stop  = br2684_seq_stop,
        .show  = br2684_seq_show,
};

static int br2684_proc_open(struct inode *inode, struct file *file)
{
        return seq_open(file, &br2684_seq_ops);
}

static struct file_operations br2684_proc_ops = {
        .owner   = THIS_MODULE,
        .open    = br2684_proc_open,
        .read    = seq_read,
        .llseek  = seq_lseek,
        .release = seq_release,
};

extern struct proc_dir_entry *atm_proc_root;    /* from proc.c */
#endif

static int __init br2684_init(void)
{
#ifdef CONFIG_PROC_FS
        struct proc_dir_entry *p;
        if ((p = create_proc_entry("br2684", 0, atm_proc_root)) == NULL)
                return -ENOMEM;
        p->proc_fops = &br2684_proc_ops;
#endif
        register_atm_ioctl(&br2684_ioctl_ops);
        return 0;
}

static void __exit br2684_exit(void)
{
        struct net_device *net_dev;
        struct br2684_dev *brdev;
        struct br2684_vcc *brvcc;
        deregister_atm_ioctl(&br2684_ioctl_ops);

#ifdef CONFIG_PROC_FS
        remove_proc_entry("br2684", atm_proc_root);
#endif

        while (!list_empty(&br2684_devs)) {
                net_dev = list_entry_brdev(br2684_devs.next);
                brdev = BRPRIV(net_dev);
                while (!list_empty(&brdev->brvccs)) {
                        brvcc = list_entry_brvcc(brdev->brvccs.next);
                        br2684_close_vcc(brvcc);
                }

                list_del(&brdev->br2684_devs);
                unregister_netdev(net_dev);
                free_netdev(net_dev);
        }
}

module_init(br2684_init);
module_exit(br2684_exit);

MODULE_AUTHOR("Marcell GAL");
MODULE_DESCRIPTION("RFC2684 bridged protocols over ATM/AAL5");
MODULE_LICENSE("GPL");