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33 results

br2684.c

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  • br2684.c 22.03 KiB
    /*
    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"
    
    /*
     * 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(__be16 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 *skb;
    	struct sk_buff_head *rq;
    	struct br2684_dev *brdev;
    	struct net_device *net_dev;
    	struct atm_backend_br2684 be;
    	unsigned long flags;
    
    	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;
    
    	rq = &sk_atm(atmvcc)->sk_receive_queue;
    
    	spin_lock_irqsave(&rq->lock, flags);
    	if (skb_queue_empty(rq)) {
    		skb = NULL;
    	} else {
    		/* NULL terminate the list.  */
    		rq->prev->next = NULL;
    		skb = rq->next;
    	}
    	rq->prev = rq->next = (struct sk_buff *)rq;
    	rq->qlen = 0;
    	spin_unlock_irqrestore(&rq->lock, flags);
    
    	while (skb) {
    		struct sk_buff *next = skb->next;
    
    		skb->next = skb->prev = NULL;
    		BRPRIV(skb->dev)->stats.rx_bytes -= skb->len;
    		BRPRIV(skb->dev)->stats.rx_packets--;
    		br2684_push(atmvcc, skb);
    
    		skb = next;
    	}
    	__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");