kernel-ark/net/8021q/vlan_dev.c
Chris Leech e83a2ea850 [VLAN]: set_rx_mode support for unicast address list
Reuse the existing logic for multicast list synchronization for the
unicast address list. The core of dev_mc_sync/unsync are split out as
__dev_addr_sync/unsync and moved from dev_mcast.c to dev.c.  These are
then used to implement dev_unicast_sync/unsync as well.

I'm working on cleaning up Intel's FCoE stack, which generates new MAC
addresses from the fibre channel device id assigned by the fabric as
per the current draft specification in T11.  When using such a
protocol in a VLAN environment it would be nice to not always be
forced into promiscuous mode, assuming the underlying Ethernet driver
supports multiple unicast addresses as well.

Signed-off-by: Chris Leech <christopher.leech@intel.com>
Signed-off-by: Patrick McHardy <kaber@trash.net>
2008-01-31 19:28:24 -08:00

715 lines
20 KiB
C

/* -*- linux-c -*-
* INET 802.1Q VLAN
* Ethernet-type device handling.
*
* Authors: Ben Greear <greearb@candelatech.com>
* Please send support related email to: netdev@vger.kernel.org
* 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
*/
static 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:
pr_debug("%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;
}
static inline void vlan_set_encap_proto(struct sk_buff *skb,
struct vlan_hdr *vhdr)
{
__be16 proto;
unsigned char *rawp;
/*
* Was a VLAN packet, grab the encapsulated protocol, which the layer
* three protocols care about.
*/
proto = vhdr->h_vlan_encapsulated_proto;
if (ntohs(proto) >= 1536) {
skb->protocol = proto;
return;
}
rawp = skb->data;
if (*(unsigned short *)rawp == 0xFFFF)
/*
* 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.
*/
skb->protocol = htons(ETH_P_802_3);
else
/*
* Real 802.2 LLC
*/
skb->protocol = htons(ETH_P_802_2);
}
/*
* 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)
{
struct vlan_hdr *vhdr;
unsigned short vid;
struct net_device_stats *stats;
unsigned short vlan_TCI;
if (dev->nd_net != &init_net)
goto err_free;
skb = skb_share_check(skb, GFP_ATOMIC);
if (skb == NULL)
goto err_free;
if (unlikely(!pskb_may_pull(skb, VLAN_HLEN)))
goto err_free;
vhdr = (struct vlan_hdr *)skb->data;
vlan_TCI = ntohs(vhdr->h_vlan_TCI);
vid = (vlan_TCI & VLAN_VID_MASK);
rcu_read_lock();
skb->dev = __find_vlan_dev(dev, vid);
if (!skb->dev) {
pr_debug("%s: ERROR: No net_device for VID: %u on dev: %s\n",
__FUNCTION__, (unsigned int)vid, dev->name);
goto err_unlock;
}
skb->dev->last_rx = jiffies;
stats = &skb->dev->stats;
stats->rx_packets++;
stats->rx_bytes += skb->len;
skb_pull_rcsum(skb, VLAN_HLEN);
skb->priority = vlan_get_ingress_priority(skb->dev,
ntohs(vhdr->h_vlan_TCI));
pr_debug("%s: priority: %u for TCI: %hu\n",
__FUNCTION__, skb->priority, ntohs(vhdr->h_vlan_TCI));
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))
skb->pkt_type = PACKET_HOST;
break;
default:
break;
}
vlan_set_encap_proto(skb, vhdr);
skb = vlan_check_reorder_header(skb);
if (!skb) {
stats->rx_errors++;
goto err_unlock;
}
netif_rx(skb);
rcu_read_unlock();
return NET_RX_SUCCESS;
err_unlock:
rcu_read_unlock();
err_free:
kfree_skb(skb);
return NET_RX_DROP;
}
static inline unsigned short
vlan_dev_get_egress_qos_mask(struct net_device *dev, struct sk_buff *skb)
{
struct vlan_priority_tci_mapping *mp;
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.
*/
static int vlan_dev_hard_header(struct sk_buff *skb, struct net_device *dev,
unsigned short type,
const void *daddr, const void *saddr,
unsigned int len)
{
struct vlan_hdr *vhdr;
unsigned short veth_TCI = 0;
int rc = 0;
int build_vlan_header = 0;
struct net_device *vdev = dev;
pr_debug("%s: skb: %p type: %hx len: %u vlan_id: %hx, daddr: %p\n",
__FUNCTION__, skb, type, len, vlan_dev_info(dev)->vlan_id,
daddr);
/* 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 = &vdev->stats;
stats->tx_dropped++;
return -ENOMEM;
}
vlan_dev_info(vdev)->cnt_inc_headroom_on_tx++;
pr_debug("%s: %s: had to grow skb\n", __FUNCTION__, vdev->name);
}
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;
}
static int vlan_dev_hard_start_xmit(struct sk_buff *skb, struct net_device *dev)
{
struct net_device_stats *stats = &dev->stats;
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) ||
vlan_dev_info(dev)->flags & VLAN_FLAG_REORDER_HDR) {
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++;
pr_debug("%s: proto to encap: 0x%hx\n",
__FUNCTION__, htons(veth->h_vlan_proto));
/* 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++;
}
pr_debug("%s: about to send skb: %p to dev: %s\n",
__FUNCTION__, skb, skb->dev->name);
pr_debug(" " MAC_FMT " " MAC_FMT " %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);
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;
}
static int vlan_dev_hwaccel_hard_start_xmit(struct sk_buff *skb,
struct net_device *dev)
{
struct net_device_stats *stats = &dev->stats;
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;
}
static 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;
}
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;
}
static 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;
}
static 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);
dev_unicast_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;
}
static int vlan_dev_set_mac_address(struct net_device *dev, void *p)
{
struct net_device *real_dev = vlan_dev_info(dev)->real_dev;
struct sockaddr *addr = p;
int err;
if (!is_valid_ether_addr(addr->sa_data))
return -EADDRNOTAVAIL;
if (!(dev->flags & IFF_UP))
goto out;
if (compare_ether_addr(addr->sa_data, real_dev->dev_addr)) {
err = dev_unicast_add(real_dev, addr->sa_data, ETH_ALEN);
if (err < 0)
return err;
}
if (compare_ether_addr(dev->dev_addr, real_dev->dev_addr))
dev_unicast_delete(real_dev, dev->dev_addr, ETH_ALEN);
out:
memcpy(dev->dev_addr, addr->sa_data, ETH_ALEN);
return 0;
}
static 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;
}
static void vlan_dev_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);
}
static void vlan_dev_set_rx_mode(struct net_device *vlan_dev)
{
dev_mc_sync(vlan_dev_info(vlan_dev)->real_dev, vlan_dev);
dev_unicast_sync(vlan_dev_info(vlan_dev)->real_dev, vlan_dev);
}
/*
* vlan network devices have devices nesting below it, and are a special
* "super class" of normal network devices; split their locks off into a
* separate class since they always nest.
*/
static struct lock_class_key vlan_netdev_xmit_lock_key;
static const struct header_ops vlan_header_ops = {
.create = vlan_dev_hard_header,
.rebuild = vlan_dev_rebuild_header,
.parse = eth_header_parse,
};
static int vlan_dev_init(struct net_device *dev)
{
struct net_device *real_dev = vlan_dev_info(dev)->real_dev;
int subclass = 0;
/* IFF_BROADCAST|IFF_MULTICAST; ??? */
dev->flags = real_dev->flags & ~IFF_UP;
dev->iflink = real_dev->ifindex;
dev->state = (real_dev->state & ((1<<__LINK_STATE_NOCARRIER) |
(1<<__LINK_STATE_DORMANT))) |
(1<<__LINK_STATE_PRESENT);
/* ipv6 shared card related stuff */
dev->dev_id = real_dev->dev_id;
if (is_zero_ether_addr(dev->dev_addr))
memcpy(dev->dev_addr, real_dev->dev_addr, dev->addr_len);
if (is_zero_ether_addr(dev->broadcast))
memcpy(dev->broadcast, real_dev->broadcast, dev->addr_len);
if (real_dev->features & NETIF_F_HW_VLAN_TX) {
dev->header_ops = real_dev->header_ops;
dev->hard_header_len = real_dev->hard_header_len;
dev->hard_start_xmit = vlan_dev_hwaccel_hard_start_xmit;
} else {
dev->header_ops = &vlan_header_ops;
dev->hard_header_len = real_dev->hard_header_len + VLAN_HLEN;
dev->hard_start_xmit = vlan_dev_hard_start_xmit;
}
if (real_dev->priv_flags & IFF_802_1Q_VLAN)
subclass = 1;
lockdep_set_class_and_subclass(&dev->_xmit_lock,
&vlan_netdev_xmit_lock_key, subclass);
return 0;
}
void vlan_setup(struct net_device *dev)
{
ether_setup(dev);
dev->priv_flags |= IFF_802_1Q_VLAN;
dev->tx_queue_len = 0;
dev->change_mtu = vlan_dev_change_mtu;
dev->init = vlan_dev_init;
dev->open = vlan_dev_open;
dev->stop = vlan_dev_stop;
dev->set_mac_address = vlan_dev_set_mac_address;
dev->set_rx_mode = vlan_dev_set_rx_mode;
dev->set_multicast_list = vlan_dev_set_rx_mode;
dev->change_rx_flags = vlan_dev_change_rx_flags;
dev->do_ioctl = vlan_dev_ioctl;
dev->destructor = free_netdev;
memset(dev->broadcast, 0, ETH_ALEN);
}