[MIPS] Sibyte: CONFIG_SIBYTE_SB1250_DUART -> CONFIG_SERIAL_SB1250_DUART

[linux-2.6] / net / 8021q / vlan_dev.c

/* -*- linux-c -*-
 * INET         802.1Q VLAN
 *              Ethernet-type device handling.
 *
 * Authors:     Ben Greear <greearb@candelatech.com>
 *              Please send support related email to: vlan@scry.wanfear.com
 *              VLAN Home Page: http://www.candelatech.com/~greear/vlan.html
 *
 * Fixes:       Mar 22 2001: Martin Bokaemper <mbokaemper@unispherenetworks.com>
 *                - reset skb->pkt_type on incoming packets when MAC was changed
 *                - see that changed MAC is saddr for outgoing packets
 *              Oct 20, 2001:  Ard van Breeman:
 *                - Fix MC-list, finally.
 *                - Flush MC-list on VLAN destroy.
 *
 *
 *              This program is free software; you can redistribute it and/or
 *              modify it under the terms of the GNU General Public License
 *              as published by the Free Software Foundation; either version
 *              2 of the License, or (at your option) any later version.
 */

#include <linux/module.h>
#include <linux/mm.h>
#include <linux/in.h>
#include <linux/init.h>
#include <asm/uaccess.h> /* for copy_from_user */
#include <linux/skbuff.h>
#include <linux/netdevice.h>
#include <linux/etherdevice.h>
#include <net/datalink.h>
#include <net/p8022.h>
#include <net/arp.h>

#include "vlan.h"
#include "vlanproc.h"
#include <linux/if_vlan.h>
#include <net/ip.h>

/*
 *      Rebuild the Ethernet MAC header. This is called after an ARP
 *      (or in future other address resolution) has completed on this
 *      sk_buff. We now let ARP fill in the other fields.
 *
 *      This routine CANNOT use cached dst->neigh!
 *      Really, it is used only when dst->neigh is wrong.
 *
 * TODO:  This needs a checkup, I'm ignorant here. --BLG
 */
int vlan_dev_rebuild_header(struct sk_buff *skb)
{
        struct net_device *dev = skb->dev;
        struct vlan_ethhdr *veth = (struct vlan_ethhdr *)(skb->data);

        switch (veth->h_vlan_encapsulated_proto) {
#ifdef CONFIG_INET
        case __constant_htons(ETH_P_IP):

                /* TODO:  Confirm this will work with VLAN headers... */
                return arp_find(veth->h_dest, skb);
#endif
        default:
                printk(VLAN_DBG
                       "%s: unable to resolve type %X addresses.\n",
                       dev->name, ntohs(veth->h_vlan_encapsulated_proto));

                memcpy(veth->h_source, dev->dev_addr, ETH_ALEN);
                break;
        }

        return 0;
}

static inline struct sk_buff *vlan_check_reorder_header(struct sk_buff *skb)
{
        if (VLAN_DEV_INFO(skb->dev)->flags & VLAN_FLAG_REORDER_HDR) {
                if (skb_shared(skb) || skb_cloned(skb)) {
                        struct sk_buff *nskb = skb_copy(skb, GFP_ATOMIC);
                        kfree_skb(skb);
                        skb = nskb;
                }
                if (skb) {
                        /* Lifted from Gleb's VLAN code... */
                        memmove(skb->data - ETH_HLEN,
                                skb->data - VLAN_ETH_HLEN, 12);
                        skb->mac_header += VLAN_HLEN;
                }
        }

        return skb;
}

/*
 *      Determine the packet's protocol ID. The rule here is that we
 *      assume 802.3 if the type field is short enough to be a length.
 *      This is normal practice and works for any 'now in use' protocol.
 *
 *  Also, at this point we assume that we ARE dealing exclusively with
 *  VLAN packets, or packets that should be made into VLAN packets based
 *  on a default VLAN ID.
 *
 *  NOTE:  Should be similar to ethernet/eth.c.
 *
 *  SANITY NOTE:  This method is called when a packet is moving up the stack
 *                towards userland.  To get here, it would have already passed
 *                through the ethernet/eth.c eth_type_trans() method.
 *  SANITY NOTE 2: We are referencing to the VLAN_HDR frields, which MAY be
 *                 stored UNALIGNED in the memory.  RISC systems don't like
 *                 such cases very much...
 *  SANITY NOTE 2a:  According to Dave Miller & Alexey, it will always be aligned,
 *                 so there doesn't need to be any of the unaligned stuff.  It has
 *                 been commented out now...  --Ben
 *
 */
int vlan_skb_recv(struct sk_buff *skb, struct net_device *dev,
                  struct packet_type* ptype, struct net_device *orig_dev)
{
        unsigned char *rawp = NULL;
        struct vlan_hdr *vhdr = (struct vlan_hdr *)(skb->data);
        unsigned short vid;
        struct net_device_stats *stats;
        unsigned short vlan_TCI;
        __be16 proto;

        /* vlan_TCI = ntohs(get_unaligned(&vhdr->h_vlan_TCI)); */
        vlan_TCI = ntohs(vhdr->h_vlan_TCI);

        vid = (vlan_TCI & VLAN_VID_MASK);

#ifdef VLAN_DEBUG
        printk(VLAN_DBG "%s: skb: %p vlan_id: %hx\n",
                __FUNCTION__, skb, vid);
#endif

        /* Ok, we will find the correct VLAN device, strip the header,
         * and then go on as usual.
         */

        /* We have 12 bits of vlan ID.
         *
         * We must not drop allow preempt until we hold a
         * reference to the device (netif_rx does that) or we
         * fail.
         */

        rcu_read_lock();
        skb->dev = __find_vlan_dev(dev, vid);
        if (!skb->dev) {
                rcu_read_unlock();

#ifdef VLAN_DEBUG
                printk(VLAN_DBG "%s: ERROR: No net_device for VID: %i on dev: %s [%i]\n",
                        __FUNCTION__, (unsigned int)(vid), dev->name, dev->ifindex);
#endif
                kfree_skb(skb);
                return -1;
        }

        skb->dev->last_rx = jiffies;

        /* Bump the rx counters for the VLAN device. */
        stats = vlan_dev_get_stats(skb->dev);
        stats->rx_packets++;
        stats->rx_bytes += skb->len;

        /* Take off the VLAN header (4 bytes currently) */
        skb_pull_rcsum(skb, VLAN_HLEN);

        /* Ok, lets check to make sure the device (dev) we
         * came in on is what this VLAN is attached to.
         */

        if (dev != VLAN_DEV_INFO(skb->dev)->real_dev) {
                rcu_read_unlock();

#ifdef VLAN_DEBUG
                printk(VLAN_DBG "%s: dropping skb: %p because came in on wrong device, dev: %s  real_dev: %s, skb_dev: %s\n",
                        __FUNCTION__, skb, dev->name,
                        VLAN_DEV_INFO(skb->dev)->real_dev->name,
                        skb->dev->name);
#endif
                kfree_skb(skb);
                stats->rx_errors++;
                return -1;
        }

        /*
         * Deal with ingress priority mapping.
         */
        skb->priority = vlan_get_ingress_priority(skb->dev, ntohs(vhdr->h_vlan_TCI));

#ifdef VLAN_DEBUG
        printk(VLAN_DBG "%s: priority: %lu  for TCI: %hu (hbo)\n",
                __FUNCTION__, (unsigned long)(skb->priority),
                ntohs(vhdr->h_vlan_TCI));
#endif

        /* The ethernet driver already did the pkt_type calculations
         * for us...
         */
        switch (skb->pkt_type) {
        case PACKET_BROADCAST: /* Yeah, stats collect these together.. */
                // stats->broadcast ++; // no such counter :-(
                break;

        case PACKET_MULTICAST:
                stats->multicast++;
                break;

        case PACKET_OTHERHOST:
                /* Our lower layer thinks this is not local, let's make sure.
                 * This allows the VLAN to have a different MAC than the underlying
                 * device, and still route correctly.
                 */
                if (!compare_ether_addr(eth_hdr(skb)->h_dest, skb->dev->dev_addr)) {
                        /* It is for our (changed) MAC-address! */
                        skb->pkt_type = PACKET_HOST;
                }
                break;
        default:
                break;
        }

        /*  Was a VLAN packet, grab the encapsulated protocol, which the layer
         * three protocols care about.
         */
        /* proto = get_unaligned(&vhdr->h_vlan_encapsulated_proto); */
        proto = vhdr->h_vlan_encapsulated_proto;

        skb->protocol = proto;
        if (ntohs(proto) >= 1536) {
                /* place it back on the queue to be handled by
                 * true layer 3 protocols.
                 */

                /* See if we are configured to re-write the VLAN header
                 * to make it look like ethernet...
                 */
                skb = vlan_check_reorder_header(skb);

                /* Can be null if skb-clone fails when re-ordering */
                if (skb) {
                        netif_rx(skb);
                } else {
                        /* TODO:  Add a more specific counter here. */
                        stats->rx_errors++;
                }
                rcu_read_unlock();
                return 0;
        }

        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) {
                skb->protocol = htons(ETH_P_802_3);
                /* place it back on the queue to be handled by true layer 3 protocols.
                 */

                /* See if we are configured to re-write the VLAN header
                 * to make it look like ethernet...
                 */
                skb = vlan_check_reorder_header(skb);

                /* Can be null if skb-clone fails when re-ordering */
                if (skb) {
                        netif_rx(skb);
                } else {
                        /* TODO:  Add a more specific counter here. */
                        stats->rx_errors++;
                }
                rcu_read_unlock();
                return 0;
        }

        /*
         *      Real 802.2 LLC
         */
        skb->protocol = htons(ETH_P_802_2);
        /* place it back on the queue to be handled by upper layer protocols.
         */

        /* See if we are configured to re-write the VLAN header
         * to make it look like ethernet...
         */
        skb = vlan_check_reorder_header(skb);

        /* Can be null if skb-clone fails when re-ordering */
        if (skb) {
                netif_rx(skb);
        } else {
                /* TODO:  Add a more specific counter here. */
                stats->rx_errors++;
        }
        rcu_read_unlock();
        return 0;
}

static inline unsigned short vlan_dev_get_egress_qos_mask(struct net_device* dev,
                                                          struct sk_buff* skb)
{
        struct vlan_priority_tci_mapping *mp =
                VLAN_DEV_INFO(dev)->egress_priority_map[(skb->priority & 0xF)];

        while (mp) {
                if (mp->priority == skb->priority) {
                        return mp->vlan_qos; /* This should already be shifted to mask
                                              * correctly with the VLAN's TCI
                                              */
                }
                mp = mp->next;
        }
        return 0;
}

/*
 *      Create the VLAN header for an arbitrary protocol layer
 *
 *      saddr=NULL      means use device source address
 *      daddr=NULL      means leave destination address (eg unresolved arp)
 *
 *  This is called when the SKB is moving down the stack towards the
 *  physical devices.
 */
int vlan_dev_hard_header(struct sk_buff *skb, struct net_device *dev,
                         unsigned short type, void *daddr, void *saddr,
                         unsigned len)
{
        struct vlan_hdr *vhdr;
        unsigned short veth_TCI = 0;
        int rc = 0;
        int build_vlan_header = 0;
        struct net_device *vdev = dev; /* save this for the bottom of the method */

#ifdef VLAN_DEBUG
        printk(VLAN_DBG "%s: skb: %p type: %hx len: %x vlan_id: %hx, daddr: %p\n",
                __FUNCTION__, skb, type, len, VLAN_DEV_INFO(dev)->vlan_id, daddr);
#endif

        /* build vlan header only if re_order_header flag is NOT set.  This
         * fixes some programs that get confused when they see a VLAN device
         * sending a frame that is VLAN encoded (the consensus is that the VLAN
         * device should look completely like an Ethernet device when the
         * REORDER_HEADER flag is set)  The drawback to this is some extra
         * header shuffling in the hard_start_xmit.  Users can turn off this
         * REORDER behaviour with the vconfig tool.
         */
        if (!(VLAN_DEV_INFO(dev)->flags & VLAN_FLAG_REORDER_HDR))
                build_vlan_header = 1;

        if (build_vlan_header) {
                vhdr = (struct vlan_hdr *) skb_push(skb, VLAN_HLEN);

                /* build the four bytes that make this a VLAN header. */

                /* Now, construct the second two bytes. This field looks something
                 * like:
                 * usr_priority: 3 bits  (high bits)
                 * CFI           1 bit
                 * VLAN ID       12 bits (low bits)
                 *
                 */
                veth_TCI = VLAN_DEV_INFO(dev)->vlan_id;
                veth_TCI |= vlan_dev_get_egress_qos_mask(dev, skb);

                vhdr->h_vlan_TCI = htons(veth_TCI);

                /*
                 *  Set the protocol type.
                 *  For a packet of type ETH_P_802_3 we put the length in here instead.
                 *  It is up to the 802.2 layer to carry protocol information.
                 */

                if (type != ETH_P_802_3) {
                        vhdr->h_vlan_encapsulated_proto = htons(type);
                } else {
                        vhdr->h_vlan_encapsulated_proto = htons(len);
                }

                skb->protocol = htons(ETH_P_8021Q);
                skb_reset_network_header(skb);
        }

        /* Before delegating work to the lower layer, enter our MAC-address */
        if (saddr == NULL)
                saddr = dev->dev_addr;

        dev = VLAN_DEV_INFO(dev)->real_dev;

        /* MPLS can send us skbuffs w/out enough space.  This check will grow the
         * skb if it doesn't have enough headroom.  Not a beautiful solution, so
         * I'll tick a counter so that users can know it's happening...  If they
         * care...
         */

        /* NOTE:  This may still break if the underlying device is not the final
         * device (and thus there are more headers to add...)  It should work for
         * good-ole-ethernet though.
         */
        if (skb_headroom(skb) < dev->hard_header_len) {
                struct sk_buff *sk_tmp = skb;
                skb = skb_realloc_headroom(sk_tmp, dev->hard_header_len);
                kfree_skb(sk_tmp);
                if (skb == NULL) {
                        struct net_device_stats *stats = vlan_dev_get_stats(vdev);
                        stats->tx_dropped++;
                        return -ENOMEM;
                }
                VLAN_DEV_INFO(vdev)->cnt_inc_headroom_on_tx++;
#ifdef VLAN_DEBUG
                printk(VLAN_DBG "%s: %s: had to grow skb.\n", __FUNCTION__, vdev->name);
#endif
        }

        if (build_vlan_header) {
                /* Now make the underlying real hard header */
                rc = dev->hard_header(skb, dev, ETH_P_8021Q, daddr, saddr, len + VLAN_HLEN);

                if (rc > 0) {
                        rc += VLAN_HLEN;
                } else if (rc < 0) {
                        rc -= VLAN_HLEN;
                }
        } else {
                /* If here, then we'll just make a normal looking ethernet frame,
                 * but, the hard_start_xmit method will insert the tag (it has to
                 * be able to do this for bridged and other skbs that don't come
                 * down the protocol stack in an orderly manner.
                 */
                rc = dev->hard_header(skb, dev, type, daddr, saddr, len);
        }

        return rc;
}

int vlan_dev_hard_start_xmit(struct sk_buff *skb, struct net_device *dev)
{
        struct net_device_stats *stats = vlan_dev_get_stats(dev);
        struct vlan_ethhdr *veth = (struct vlan_ethhdr *)(skb->data);

        /* Handle non-VLAN frames if they are sent to us, for example by DHCP.
         *
         * NOTE: THIS ASSUMES DIX ETHERNET, SPECIFICALLY NOT SUPPORTING
         * OTHER THINGS LIKE FDDI/TokenRing/802.3 SNAPs...
         */

        if (veth->h_vlan_proto != htons(ETH_P_8021Q)) {
                int orig_headroom = skb_headroom(skb);
                unsigned short veth_TCI;

                /* This is not a VLAN frame...but we can fix that! */
                VLAN_DEV_INFO(dev)->cnt_encap_on_xmit++;

#ifdef VLAN_DEBUG
                printk(VLAN_DBG "%s: proto to encap: 0x%hx (hbo)\n",
                        __FUNCTION__, htons(veth->h_vlan_proto));
#endif
                /* Construct the second two bytes. This field looks something
                 * like:
                 * usr_priority: 3 bits  (high bits)
                 * CFI           1 bit
                 * VLAN ID       12 bits (low bits)
                 */
                veth_TCI = VLAN_DEV_INFO(dev)->vlan_id;
                veth_TCI |= vlan_dev_get_egress_qos_mask(dev, skb);

                skb = __vlan_put_tag(skb, veth_TCI);
                if (!skb) {
                        stats->tx_dropped++;
                        return 0;
                }

                if (orig_headroom < VLAN_HLEN) {
                        VLAN_DEV_INFO(dev)->cnt_inc_headroom_on_tx++;
                }
        }

#ifdef VLAN_DEBUG
        printk(VLAN_DBG "%s: about to send skb: %p to dev: %s\n",
                __FUNCTION__, skb, skb->dev->name);
        printk(VLAN_DBG "  %2hx.%2hx.%2hx.%2xh.%2hx.%2hx %2hx.%2hx.%2hx.%2hx.%2hx.%2hx %4hx %4hx %4hx\n",
               veth->h_dest[0], veth->h_dest[1], veth->h_dest[2], veth->h_dest[3], veth->h_dest[4], veth->h_dest[5],
               veth->h_source[0], veth->h_source[1], veth->h_source[2], veth->h_source[3], veth->h_source[4], veth->h_source[5],
               veth->h_vlan_proto, veth->h_vlan_TCI, veth->h_vlan_encapsulated_proto);
#endif

        stats->tx_packets++; /* for statics only */
        stats->tx_bytes += skb->len;

        skb->dev = VLAN_DEV_INFO(dev)->real_dev;
        dev_queue_xmit(skb);

        return 0;
}

int vlan_dev_hwaccel_hard_start_xmit(struct sk_buff *skb, struct net_device *dev)
{
        struct net_device_stats *stats = vlan_dev_get_stats(dev);
        unsigned short veth_TCI;

        /* Construct the second two bytes. This field looks something
         * like:
         * usr_priority: 3 bits  (high bits)
         * CFI           1 bit
         * VLAN ID       12 bits (low bits)
         */
        veth_TCI = VLAN_DEV_INFO(dev)->vlan_id;
        veth_TCI |= vlan_dev_get_egress_qos_mask(dev, skb);
        skb = __vlan_hwaccel_put_tag(skb, veth_TCI);

        stats->tx_packets++;
        stats->tx_bytes += skb->len;

        skb->dev = VLAN_DEV_INFO(dev)->real_dev;
        dev_queue_xmit(skb);

        return 0;
}

int vlan_dev_change_mtu(struct net_device *dev, int new_mtu)
{
        /* TODO: gotta make sure the underlying layer can handle it,
         * maybe an IFF_VLAN_CAPABLE flag for devices?
         */
        if (VLAN_DEV_INFO(dev)->real_dev->mtu < new_mtu)
                return -ERANGE;

        dev->mtu = new_mtu;

        return 0;
}

void vlan_dev_set_ingress_priority(const struct net_device *dev,
                                   u32 skb_prio, short vlan_prio)
{
        struct vlan_dev_info *vlan = VLAN_DEV_INFO(dev);

        if (vlan->ingress_priority_map[vlan_prio & 0x7] && !skb_prio)
                vlan->nr_ingress_mappings--;
        else if (!vlan->ingress_priority_map[vlan_prio & 0x7] && skb_prio)
                vlan->nr_ingress_mappings++;

        vlan->ingress_priority_map[vlan_prio & 0x7] = skb_prio;
}

int vlan_dev_set_egress_priority(const struct net_device *dev,
                                 u32 skb_prio, short vlan_prio)
{
        struct vlan_dev_info *vlan = VLAN_DEV_INFO(dev);
        struct vlan_priority_tci_mapping *mp = NULL;
        struct vlan_priority_tci_mapping *np;
        u32 vlan_qos = (vlan_prio << 13) & 0xE000;

        /* See if a priority mapping exists.. */
        mp = vlan->egress_priority_map[skb_prio & 0xF];
        while (mp) {
                if (mp->priority == skb_prio) {
                        if (mp->vlan_qos && !vlan_qos)
                                vlan->nr_egress_mappings--;
                        else if (!mp->vlan_qos && vlan_qos)
                                vlan->nr_egress_mappings++;
                        mp->vlan_qos = vlan_qos;
                        return 0;
                }
                mp = mp->next;
        }

        /* Create a new mapping then. */
        mp = vlan->egress_priority_map[skb_prio & 0xF];
        np = kmalloc(sizeof(struct vlan_priority_tci_mapping), GFP_KERNEL);
        if (!np)
                return -ENOBUFS;

        np->next = mp;
        np->priority = skb_prio;
        np->vlan_qos = vlan_qos;
        vlan->egress_priority_map[skb_prio & 0xF] = np;
        if (vlan_qos)
                vlan->nr_egress_mappings++;
        return 0;
}

/* Flags are defined in the vlan_flags enum in include/linux/if_vlan.h file. */
int vlan_dev_set_vlan_flag(const struct net_device *dev,
                           u32 flag, short flag_val)
{
        /* verify flag is supported */
        if (flag == VLAN_FLAG_REORDER_HDR) {
                if (flag_val) {
                        VLAN_DEV_INFO(dev)->flags |= VLAN_FLAG_REORDER_HDR;
                } else {
                        VLAN_DEV_INFO(dev)->flags &= ~VLAN_FLAG_REORDER_HDR;
                }
                return 0;
        }
        printk(KERN_ERR "%s: flag %i is not valid.\n", __FUNCTION__, flag);
        return -EINVAL;
}

void vlan_dev_get_realdev_name(const struct net_device *dev, char *result)
{
        strncpy(result, VLAN_DEV_INFO(dev)->real_dev->name, 23);
}

void vlan_dev_get_vid(const struct net_device *dev, unsigned short *result)
{
        *result = VLAN_DEV_INFO(dev)->vlan_id;
}

int vlan_dev_open(struct net_device *dev)
{
        struct vlan_dev_info *vlan = VLAN_DEV_INFO(dev);
        struct net_device *real_dev = vlan->real_dev;
        int err;

        if (!(real_dev->flags & IFF_UP))
                return -ENETDOWN;

        if (compare_ether_addr(dev->dev_addr, real_dev->dev_addr)) {
                err = dev_unicast_add(real_dev, dev->dev_addr, ETH_ALEN);
                if (err < 0)
                        return err;
        }
        memcpy(vlan->real_dev_addr, real_dev->dev_addr, ETH_ALEN);

        if (dev->flags & IFF_ALLMULTI)
                dev_set_allmulti(real_dev, 1);
        if (dev->flags & IFF_PROMISC)
                dev_set_promiscuity(real_dev, 1);

        return 0;
}

int vlan_dev_stop(struct net_device *dev)
{
        struct net_device *real_dev = VLAN_DEV_INFO(dev)->real_dev;

        dev_mc_unsync(real_dev, dev);
        if (dev->flags & IFF_ALLMULTI)
                dev_set_allmulti(real_dev, -1);
        if (dev->flags & IFF_PROMISC)
                dev_set_promiscuity(real_dev, -1);

        if (compare_ether_addr(dev->dev_addr, real_dev->dev_addr))
                dev_unicast_delete(real_dev, dev->dev_addr, dev->addr_len);

        return 0;
}

int vlan_dev_ioctl(struct net_device *dev, struct ifreq *ifr, int cmd)
{
        struct net_device *real_dev = VLAN_DEV_INFO(dev)->real_dev;
        struct ifreq ifrr;
        int err = -EOPNOTSUPP;

        strncpy(ifrr.ifr_name, real_dev->name, IFNAMSIZ);
        ifrr.ifr_ifru = ifr->ifr_ifru;

        switch(cmd) {
        case SIOCGMIIPHY:
        case SIOCGMIIREG:
        case SIOCSMIIREG:
                if (real_dev->do_ioctl && netif_device_present(real_dev))
                        err = real_dev->do_ioctl(real_dev, &ifrr, cmd);
                break;
        }

        if (!err)
                ifr->ifr_ifru = ifrr.ifr_ifru;

        return err;
}

void vlan_change_rx_flags(struct net_device *dev, int change)
{
        struct net_device *real_dev = VLAN_DEV_INFO(dev)->real_dev;

        if (change & IFF_ALLMULTI)
                dev_set_allmulti(real_dev, dev->flags & IFF_ALLMULTI ? 1 : -1);
        if (change & IFF_PROMISC)
                dev_set_promiscuity(real_dev, dev->flags & IFF_PROMISC ? 1 : -1);
}

/** Taken from Gleb + Lennert's VLAN code, and modified... */
void vlan_dev_set_multicast_list(struct net_device *vlan_dev)
{
        dev_mc_sync(VLAN_DEV_INFO(vlan_dev)->real_dev, vlan_dev);
}