dev.c

static int softnet_seq_show(struct seq_file *seq, void *v)
{
	struct netif_rx_stats *s = v;

	seq_printf(seq, "%08x %08x %08x %08x %08x %08x %08x %08x %08x\n",
		   s->total, s->dropped, s->time_squeeze, 0,
		   0, 0, 0, 0, /* was fastroute */
		   s->cpu_collision );
	return 0;
}

static struct seq_operations dev_seq_ops = {
	.start = dev_seq_start,
	.next  = dev_seq_next,
	.stop  = dev_seq_stop,
	.show  = dev_seq_show,
};

static int dev_seq_open(struct inode *inode, struct file *file)
{
	return seq_open(file, &dev_seq_ops);
}

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

static struct seq_operations softnet_seq_ops = {
	.start = softnet_seq_start,
	.next  = softnet_seq_next,
	.stop  = softnet_seq_stop,
	.show  = softnet_seq_show,
};

static int softnet_seq_open(struct inode *inode, struct file *file)
{
	return seq_open(file, &softnet_seq_ops);
}

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

#ifdef CONFIG_WIRELESS_EXT
extern int wireless_proc_init(void);
#else
#define wireless_proc_init() 0
#endif

static int __init dev_proc_init(void)
{
	int rc = -ENOMEM;

	if (!proc_net_fops_create("dev", S_IRUGO, &dev_seq_fops))
		goto out;
	if (!proc_net_fops_create("softnet_stat", S_IRUGO, &softnet_seq_fops))
		goto out_dev;
	if (wireless_proc_init())
		goto out_softnet;
	rc = 0;
out:
	return rc;
out_softnet:
	proc_net_remove("softnet_stat");
out_dev:
	proc_net_remove("dev");
	goto out;
}
#else
#define dev_proc_init() 0
#endif	/* CONFIG_PROC_FS */


/**
 *	netdev_set_master	-	set up master/slave pair
 *	@slave: slave device
 *	@master: new master device
 *
 *	Changes the master device of the slave. Pass %NULL to break the
 *	bonding. The caller must hold the RTNL semaphore. On a failure
 *	a negative errno code is returned. On success the reference counts
 *	are adjusted, %RTM_NEWLINK is sent to the routing socket and the
 *	function returns zero.
 */
int netdev_set_master(struct net_device *slave, struct net_device *master)
{
	struct net_device *old = slave->master;

	ASSERT_RTNL();

	if (master) {
		if (old)
			return -EBUSY;
		dev_hold(master);
	}

	slave->master = master;
	
	synchronize_net();

	if (old)
		dev_put(old);

	if (master)
		slave->flags |= IFF_SLAVE;
	else
		slave->flags &= ~IFF_SLAVE;

	rtmsg_ifinfo(RTM_NEWLINK, slave, IFF_SLAVE);
	return 0;
}

/**
 *	dev_set_promiscuity	- update promiscuity count on a device
 *	@dev: device
 *	@inc: modifier
 *
 *	Add or remove promsicuity from a device. While the count in the device
 *	remains above zero the interface remains promiscuous. Once it hits zero
 *	the device reverts back to normal filtering operation. A negative inc
 *	value is used to drop promiscuity on the device.
 */
void dev_set_promiscuity(struct net_device *dev, int inc)
{
	unsigned short old_flags = dev->flags;

	if ((dev->promiscuity += inc) == 0)
		dev->flags &= ~IFF_PROMISC;
	else
		dev->flags |= IFF_PROMISC;
	if (dev->flags != old_flags) {
		dev_mc_upload(dev);
		printk(KERN_INFO "device %s %s promiscuous mode\n",
		       dev->name, (dev->flags & IFF_PROMISC) ? "entered" :
		       					       "left");
	}
}

/**
 *	dev_set_allmulti	- update allmulti count on a device
 *	@dev: device
 *	@inc: modifier
 *
 *	Add or remove reception of all multicast frames to a device. While the
 *	count in the device remains above zero the interface remains listening
 *	to all interfaces. Once it hits zero the device reverts back to normal
 *	filtering operation. A negative @inc value is used to drop the counter
 *	when releasing a resource needing all multicasts.
 */

void dev_set_allmulti(struct net_device *dev, int inc)
{
	unsigned short old_flags = dev->flags;

	dev->flags |= IFF_ALLMULTI;
	if ((dev->allmulti += inc) == 0)
		dev->flags &= ~IFF_ALLMULTI;
	if (dev->flags ^ old_flags)
		dev_mc_upload(dev);
}

unsigned dev_get_flags(const struct net_device *dev)
{
	unsigned flags;

	flags = (dev->flags & ~(IFF_PROMISC |
				IFF_ALLMULTI |
				IFF_RUNNING |
				IFF_LOWER_UP |
				IFF_DORMANT)) |
		(dev->gflags & (IFF_PROMISC |
				IFF_ALLMULTI));

	if (netif_running(dev)) {
		if (netif_oper_up(dev))
			flags |= IFF_RUNNING;
		if (netif_carrier_ok(dev))
			flags |= IFF_LOWER_UP;
		if (netif_dormant(dev))
			flags |= IFF_DORMANT;
	}

	return flags;
}

int dev_change_flags(struct net_device *dev, unsigned flags)
{
	int ret;
	int old_flags = dev->flags;

	/*
	 *	Set the flags on our device.
	 */

	dev->flags = (flags & (IFF_DEBUG | IFF_NOTRAILERS | IFF_NOARP |
			       IFF_DYNAMIC | IFF_MULTICAST | IFF_PORTSEL |
			       IFF_AUTOMEDIA)) |
		     (dev->flags & (IFF_UP | IFF_VOLATILE | IFF_PROMISC |
				    IFF_ALLMULTI));

	/*
	 *	Load in the correct multicast list now the flags have changed.
	 */

	dev_mc_upload(dev);

	/*
	 *	Have we downed the interface. We handle IFF_UP ourselves
	 *	according to user attempts to set it, rather than blindly
	 *	setting it.
	 */

	ret = 0;
	if ((old_flags ^ flags) & IFF_UP) {	/* Bit is different  ? */
		ret = ((old_flags & IFF_UP) ? dev_close : dev_open)(dev);

		if (!ret)
			dev_mc_upload(dev);
	}

	if (dev->flags & IFF_UP &&
	    ((old_flags ^ dev->flags) &~ (IFF_UP | IFF_PROMISC | IFF_ALLMULTI |
					  IFF_VOLATILE)))
		notifier_call_chain(&netdev_chain, NETDEV_CHANGE, dev);

	if ((flags ^ dev->gflags) & IFF_PROMISC) {
		int inc = (flags & IFF_PROMISC) ? +1 : -1;
		dev->gflags ^= IFF_PROMISC;
		dev_set_promiscuity(dev, inc);
	}

	/* NOTE: order of synchronization of IFF_PROMISC and IFF_ALLMULTI
	   is important. Some (broken) drivers set IFF_PROMISC, when
	   IFF_ALLMULTI is requested not asking us and not reporting.
	 */
	if ((flags ^ dev->gflags) & IFF_ALLMULTI) {
		int inc = (flags & IFF_ALLMULTI) ? +1 : -1;
		dev->gflags ^= IFF_ALLMULTI;
		dev_set_allmulti(dev, inc);
	}

	if (old_flags ^ dev->flags)
		rtmsg_ifinfo(RTM_NEWLINK, dev, old_flags ^ dev->flags);

	return ret;
}

int dev_set_mtu(struct net_device *dev, int new_mtu)
{
	int err;

	if (new_mtu == dev->mtu)
		return 0;

	/*	MTU must be positive.	 */
	if (new_mtu < 0)
		return -EINVAL;

	if (!netif_device_present(dev))
		return -ENODEV;

	err = 0;
	if (dev->change_mtu)
		err = dev->change_mtu(dev, new_mtu);
	else
		dev->mtu = new_mtu;
	if (!err && dev->flags & IFF_UP)
		notifier_call_chain(&netdev_chain,
				    NETDEV_CHANGEMTU, dev);
	return err;
}

int dev_set_mac_address(struct net_device *dev, struct sockaddr *sa)
{
	int err;

	if (!dev->set_mac_address)
		return -EOPNOTSUPP;
	if (sa->sa_family != dev->type)
		return -EINVAL;
	if (!netif_device_present(dev))
		return -ENODEV;
	err = dev->set_mac_address(dev, sa);
	if (!err)
		notifier_call_chain(&netdev_chain, NETDEV_CHANGEADDR, dev);
	return err;
}

/*
 *	Perform the SIOCxIFxxx calls.
 */
static int dev_ifsioc(struct ifreq *ifr, unsigned int cmd)
{
	int err;
	struct net_device *dev = __dev_get_by_name(ifr->ifr_name);

	if (!dev)
		return -ENODEV;

	switch (cmd) {
		case SIOCGIFFLAGS:	/* Get interface flags */
			ifr->ifr_flags = dev_get_flags(dev);
			return 0;

		case SIOCSIFFLAGS:	/* Set interface flags */
			return dev_change_flags(dev, ifr->ifr_flags);

		case SIOCGIFMETRIC:	/* Get the metric on the interface
					   (currently unused) */
			ifr->ifr_metric = 0;
			return 0;

		case SIOCSIFMETRIC:	/* Set the metric on the interface
					   (currently unused) */
			return -EOPNOTSUPP;

		case SIOCGIFMTU:	/* Get the MTU of a device */
			ifr->ifr_mtu = dev->mtu;
			return 0;

		case SIOCSIFMTU:	/* Set the MTU of a device */
			return dev_set_mtu(dev, ifr->ifr_mtu);

		case SIOCGIFHWADDR:
			if (!dev->addr_len)
				memset(ifr->ifr_hwaddr.sa_data, 0, sizeof ifr->ifr_hwaddr.sa_data);
			else
				memcpy(ifr->ifr_hwaddr.sa_data, dev->dev_addr,
				       min(sizeof ifr->ifr_hwaddr.sa_data, (size_t) dev->addr_len));
			ifr->ifr_hwaddr.sa_family = dev->type;
			return 0;

		case SIOCSIFHWADDR:
			return dev_set_mac_address(dev, &ifr->ifr_hwaddr);

		case SIOCSIFHWBROADCAST:
			if (ifr->ifr_hwaddr.sa_family != dev->type)
				return -EINVAL;
			memcpy(dev->broadcast, ifr->ifr_hwaddr.sa_data,
			       min(sizeof ifr->ifr_hwaddr.sa_data, (size_t) dev->addr_len));
			notifier_call_chain(&netdev_chain,
					    NETDEV_CHANGEADDR, dev);
			return 0;

		case SIOCGIFMAP:
			ifr->ifr_map.mem_start = dev->mem_start;
			ifr->ifr_map.mem_end   = dev->mem_end;
			ifr->ifr_map.base_addr = dev->base_addr;
			ifr->ifr_map.irq       = dev->irq;
			ifr->ifr_map.dma       = dev->dma;
			ifr->ifr_map.port      = dev->if_port;
			return 0;

		case SIOCSIFMAP:
			if (dev->set_config) {
				if (!netif_device_present(dev))
					return -ENODEV;
				return dev->set_config(dev, &ifr->ifr_map);
			}
			return -EOPNOTSUPP;

		case SIOCADDMULTI:
			if (!dev->set_multicast_list ||
			    ifr->ifr_hwaddr.sa_family != AF_UNSPEC)
				return -EINVAL;
			if (!netif_device_present(dev))
				return -ENODEV;
			return dev_mc_add(dev, ifr->ifr_hwaddr.sa_data,
					  dev->addr_len, 1);

		case SIOCDELMULTI:
			if (!dev->set_multicast_list ||
			    ifr->ifr_hwaddr.sa_family != AF_UNSPEC)
				return -EINVAL;
			if (!netif_device_present(dev))
				return -ENODEV;
			return dev_mc_delete(dev, ifr->ifr_hwaddr.sa_data,
					     dev->addr_len, 1);

		case SIOCGIFINDEX:
			ifr->ifr_ifindex = dev->ifindex;
			return 0;

		case SIOCGIFTXQLEN:
			ifr->ifr_qlen = dev->tx_queue_len;
			return 0;

		case SIOCSIFTXQLEN:
			if (ifr->ifr_qlen < 0)
				return -EINVAL;
			dev->tx_queue_len = ifr->ifr_qlen;
			return 0;

		case SIOCSIFNAME:
			ifr->ifr_newname[IFNAMSIZ-1] = '\0';
			return dev_change_name(dev, ifr->ifr_newname);

		/*
		 *	Unknown or private ioctl
		 */

		default:
			if ((cmd >= SIOCDEVPRIVATE &&
			    cmd <= SIOCDEVPRIVATE + 15) ||
			    cmd == SIOCBONDENSLAVE ||
			    cmd == SIOCBONDRELEASE ||
			    cmd == SIOCBONDSETHWADDR ||
			    cmd == SIOCBONDSLAVEINFOQUERY ||
			    cmd == SIOCBONDINFOQUERY ||
			    cmd == SIOCBONDCHANGEACTIVE ||
			    cmd == SIOCGMIIPHY ||
			    cmd == SIOCGMIIREG ||
			    cmd == SIOCSMIIREG ||
			    cmd == SIOCBRADDIF ||
			    cmd == SIOCBRDELIF ||
			    cmd == SIOCWANDEV) {
				err = -EOPNOTSUPP;
				if (dev->do_ioctl) {
					if (netif_device_present(dev))
						err = dev->do_ioctl(dev, ifr,
								    cmd);
					else
						err = -ENODEV;
				}
			} else
				err = -EINVAL;

	}
	return err;
}

/*
 *	This function handles all "interface"-type I/O control requests. The actual
 *	'doing' part of this is dev_ifsioc above.
 */

/**
 *	dev_ioctl	-	network device ioctl
 *	@cmd: command to issue
 *	@arg: pointer to a struct ifreq in user space
 *
 *	Issue ioctl functions to devices. This is normally called by the
 *	user space syscall interfaces but can sometimes be useful for
 *	other purposes. The return value is the return from the syscall if
 *	positive or a negative errno code on error.
 */

int dev_ioctl(unsigned int cmd, void __user *arg)
{
	struct ifreq ifr;
	int ret;
	char *colon;

	/* One special case: SIOCGIFCONF takes ifconf argument
	   and requires shared lock, because it sleeps writing
	   to user space.
	 */

	if (cmd == SIOCGIFCONF) {
		rtnl_lock();
		ret = dev_ifconf((char __user *) arg);
		rtnl_unlock();
		return ret;
	}
	if (cmd == SIOCGIFNAME)
		return dev_ifname((struct ifreq __user *)arg);

	if (copy_from_user(&ifr, arg, sizeof(struct ifreq)))
		return -EFAULT;

	ifr.ifr_name[IFNAMSIZ-1] = 0;

	colon = strchr(ifr.ifr_name, ':');
	if (colon)
		*colon = 0;

	/*
	 *	See which interface the caller is talking about.
	 */

	switch (cmd) {
		/*
		 *	These ioctl calls:
		 *	- can be done by all.
		 *	- atomic and do not require locking.
		 *	- return a value
		 */
		case SIOCGIFFLAGS:
		case SIOCGIFMETRIC:
		case SIOCGIFMTU:
		case SIOCGIFHWADDR:
		case SIOCGIFSLAVE:
		case SIOCGIFMAP:
		case SIOCGIFINDEX:
		case SIOCGIFTXQLEN:
			dev_load(ifr.ifr_name);
			read_lock(&dev_base_lock);
			ret = dev_ifsioc(&ifr, cmd);
			read_unlock(&dev_base_lock);
			if (!ret) {
				if (colon)
					*colon = ':';
				if (copy_to_user(arg, &ifr,
						 sizeof(struct ifreq)))
					ret = -EFAULT;
			}
			return ret;

		case SIOCETHTOOL:
			dev_load(ifr.ifr_name);
			rtnl_lock();
			ret = dev_ethtool(&ifr);
			rtnl_unlock();
			if (!ret) {
				if (colon)
					*colon = ':';
				if (copy_to_user(arg, &ifr,
						 sizeof(struct ifreq)))
					ret = -EFAULT;
			}
			return ret;

		/*
		 *	These ioctl calls:
		 *	- require superuser power.
		 *	- require strict serialization.
		 *	- return a value
		 */
		case SIOCGMIIPHY:
		case SIOCGMIIREG:
		case SIOCSIFNAME:
			if (!capable(CAP_NET_ADMIN))
				return -EPERM;
			dev_load(ifr.ifr_name);
			rtnl_lock();
			ret = dev_ifsioc(&ifr, cmd);
			rtnl_unlock();
			if (!ret) {
				if (colon)
					*colon = ':';
				if (copy_to_user(arg, &ifr,
						 sizeof(struct ifreq)))
					ret = -EFAULT;
			}
			return ret;

		/*
		 *	These ioctl calls:
		 *	- require superuser power.
		 *	- require strict serialization.
		 *	- do not return a value
		 */
		case SIOCSIFFLAGS:
		case SIOCSIFMETRIC:
		case SIOCSIFMTU:
		case SIOCSIFMAP:
		case SIOCSIFHWADDR:
		case SIOCSIFSLAVE:
		case SIOCADDMULTI:
		case SIOCDELMULTI:
		case SIOCSIFHWBROADCAST:
		case SIOCSIFTXQLEN:
		case SIOCSMIIREG:
		case SIOCBONDENSLAVE:
		case SIOCBONDRELEASE:
		case SIOCBONDSETHWADDR:
		case SIOCBONDCHANGEACTIVE:
		case SIOCBRADDIF:
		case SIOCBRDELIF:
			if (!capable(CAP_NET_ADMIN))
				return -EPERM;
			/* fall through */
		case SIOCBONDSLAVEINFOQUERY:
		case SIOCBONDINFOQUERY:
			dev_load(ifr.ifr_name);
			rtnl_lock();
			ret = dev_ifsioc(&ifr, cmd);
			rtnl_unlock();
			return ret;

		case SIOCGIFMEM:
			/* Get the per device memory space. We can add this but
			 * currently do not support it */
		case SIOCSIFMEM:
			/* Set the per device memory buffer space.
			 * Not applicable in our case */
		case SIOCSIFLINK:
			return -EINVAL;

		/*
		 *	Unknown or private ioctl.
		 */
		default:
			if (cmd == SIOCWANDEV ||
			    (cmd >= SIOCDEVPRIVATE &&
			     cmd <= SIOCDEVPRIVATE + 15)) {
				dev_load(ifr.ifr_name);
				rtnl_lock();
				ret = dev_ifsioc(&ifr, cmd);
				rtnl_unlock();
				if (!ret && copy_to_user(arg, &ifr,
							 sizeof(struct ifreq)))
					ret = -EFAULT;
				return ret;
			}
#ifdef CONFIG_WIRELESS_EXT
			/* Take care of Wireless Extensions */
			if (cmd >= SIOCIWFIRST && cmd <= SIOCIWLAST) {
				/* If command is `set a parameter', or
				 * `get the encoding parameters', check if
				 * the user has the right to do it */
				if (IW_IS_SET(cmd) || cmd == SIOCGIWENCODE) {
					if (!capable(CAP_NET_ADMIN))
						return -EPERM;
				}
				dev_load(ifr.ifr_name);
				rtnl_lock();
				/* Follow me in net/core/wireless.c */
				ret = wireless_process_ioctl(&ifr, cmd);
				rtnl_unlock();
				if (IW_IS_GET(cmd) &&
				    copy_to_user(arg, &ifr,
					    	 sizeof(struct ifreq)))
					ret = -EFAULT;
				return ret;
			}
#endif	/* CONFIG_WIRELESS_EXT */
			return -EINVAL;
	}
}


/**
 *	dev_new_index	-	allocate an ifindex
 *
 *	Returns a suitable unique value for a new device interface
 *	number.  The caller must hold the rtnl semaphore or the
 *	dev_base_lock to be sure it remains unique.
 */
static int dev_new_index(void)
{
	static int ifindex;
	for (;;) {
		if (++ifindex <= 0)
			ifindex = 1;
		if (!__dev_get_by_index(ifindex))
			return ifindex;
	}
}

static int dev_boot_phase = 1;

/* Delayed registration/unregisteration */
static DEFINE_SPINLOCK(net_todo_list_lock);
static struct list_head net_todo_list = LIST_HEAD_INIT(net_todo_list);

static inline void net_set_todo(struct net_device *dev)
{
	spin_lock(&net_todo_list_lock);
	list_add_tail(&dev->todo_list, &net_todo_list);
	spin_unlock(&net_todo_list_lock);
}

/**
 *	register_netdevice	- register a network device
 *	@dev: device to register
 *
 *	Take a completed network device structure and add it to the kernel
 *	interfaces. A %NETDEV_REGISTER message is sent to the netdev notifier
 *	chain. 0 is returned on success. A negative errno code is returned
 *	on a failure to set up the device, or if the name is a duplicate.
 *
 *	Callers must hold the rtnl semaphore. You may want
 *	register_netdev() instead of this.
 *
 *	BUGS:
 *	The locking appears insufficient to guarantee two parallel registers
 *	will not get the same name.
 */

int register_netdevice(struct net_device *dev)
{
	struct hlist_head *head;
	struct hlist_node *p;
	int ret;

	BUG_ON(dev_boot_phase);
	ASSERT_RTNL();

	/* When net_device's are persistent, this will be fatal. */
	BUG_ON(dev->reg_state != NETREG_UNINITIALIZED);

	spin_lock_init(&dev->queue_lock);
	spin_lock_init(&dev->xmit_lock);
	dev->xmit_lock_owner = -1;
#ifdef CONFIG_NET_CLS_ACT
	spin_lock_init(&dev->ingress_lock);
#endif

	ret = alloc_divert_blk(dev);
	if (ret)
		goto out;

	dev->iflink = -1;

	/* Init, if this function is available */
	if (dev->init) {
		ret = dev->init(dev);
		if (ret) {
			if (ret > 0)
				ret = -EIO;
			goto out_err;
		}
	}
 
	if (!dev_valid_name(dev->name)) {
		ret = -EINVAL;
		goto out_err;
	}

	dev->ifindex = dev_new_index();
	if (dev->iflink == -1)
		dev->iflink = dev->ifindex;

	/* Check for existence of name */
	head = dev_name_hash(dev->name);
	hlist_for_each(p, head) {
		struct net_device *d
			= hlist_entry(p, struct net_device, name_hlist);
		if (!strncmp(d->name, dev->name, IFNAMSIZ)) {
			ret = -EEXIST;
 			goto out_err;
		}
 	}

	/* Fix illegal SG+CSUM combinations. */
	if ((dev->features & NETIF_F_SG) &&
	    !(dev->features & (NETIF_F_IP_CSUM |
			       NETIF_F_NO_CSUM |
			       NETIF_F_HW_CSUM))) {
		printk("%s: Dropping NETIF_F_SG since no checksum feature.\n",
		       dev->name);
		dev->features &= ~NETIF_F_SG;
	}

	/* TSO requires that SG is present as well. */
	if ((dev->features & NETIF_F_TSO) &&
	    !(dev->features & NETIF_F_SG)) {
		printk("%s: Dropping NETIF_F_TSO since no SG feature.\n",
		       dev->name);
		dev->features &= ~NETIF_F_TSO;
	}
	if (dev->features & NETIF_F_UFO) {
		if (!(dev->features & NETIF_F_HW_CSUM)) {
			printk(KERN_ERR "%s: Dropping NETIF_F_UFO since no "
					"NETIF_F_HW_CSUM feature.\n",
							dev->name);
			dev->features &= ~NETIF_F_UFO;
		}
		if (!(dev->features & NETIF_F_SG)) {
			printk(KERN_ERR "%s: Dropping NETIF_F_UFO since no "
					"NETIF_F_SG feature.\n",
					dev->name);
			dev->features &= ~NETIF_F_UFO;
		}
	}

	/*
	 *	nil rebuild_header routine,
	 *	that should be never called and used as just bug trap.
	 */

	if (!dev->rebuild_header)
		dev->rebuild_header = default_rebuild_header;

	/*
	 *	Default initial state at registry is that the
	 *	device is present.
	 */

	set_bit(__LINK_STATE_PRESENT, &dev->state);

	dev->next = NULL;
	dev_init_scheduler(dev);
	write_lock_bh(&dev_base_lock);
	*dev_tail = dev;
	dev_tail = &dev->next;
	hlist_add_head(&dev->name_hlist, head);
	hlist_add_head(&dev->index_hlist, dev_index_hash(dev->ifindex));
	dev_hold(dev);
	dev->reg_state = NETREG_REGISTERING;
	write_unlock_bh(&dev_base_lock);

	/* Notify protocols, that a new device appeared. */
	notifier_call_chain(&netdev_chain, NETDEV_REGISTER, dev);

	/* Finish registration after unlock */
	net_set_todo(dev);
	ret = 0;

out:
	return ret;
out_err:
	free_divert_blk(dev);
	goto out;
}

/**
 *	register_netdev	- register a network device
 *	@dev: device to register
 *
 *	Take a completed network device structure and add it to the kernel
 *	interfaces. A %NETDEV_REGISTER message is sent to the netdev notifier
 *	chain. 0 is returned on success. A negative errno code is returned
 *	on a failure to set up the device, or if the name is a duplicate.
 *
 *	This is a wrapper around register_netdev that takes the rtnl semaphore
 *	and expands the device name if you passed a format string to
 *	alloc_netdev.
 */
int register_netdev(struct net_device *dev)
{
	int err;

	rtnl_lock();

	/*
	 * If the name is a format string the caller wants us to do a
	 * name allocation.
	 */
	if (strchr(dev->name, '%')) {
		err = dev_alloc_name(dev, dev->name);
		if (err < 0)
			goto out;
	}
	
	/*
	 * Back compatibility hook. Kill this one in 2.5
	 */
	if (dev->name[0] == 0 || dev->name[0] == ' ') {
		err = dev_alloc_name(dev, "eth%d");
		if (err < 0)
			goto out;
	}

	err = register_netdevice(dev);
out:
	rtnl_unlock();
	return err;
}
EXPORT_SYMBOL(register_netdev);

/*
 * netdev_wait_allrefs - wait until all references are gone.
 *
 * This is called when unregistering network devices.
 *
 * Any protocol or device that holds a reference should register
 * for netdevice notification, and cleanup and put back the
 * reference if they receive an UNREGISTER event.
 * We can get stuck here if buggy protocols don't correctly
 * call dev_put. 
 */
static void netdev_wait_allrefs(struct net_device *dev)
{
	unsigned long rebroadcast_time, warning_time;

	rebroadcast_time = warning_time = jiffies;
	while (atomic_read(&dev->refcnt) != 0) {
		if (time_after(jiffies, rebroadcast_time + 1 * HZ)) {
			rtnl_lock();

			/* Rebroadcast unregister notification */
			notifier_call_chain(&netdev_chain,
					    NETDEV_UNREGISTER, dev);

			if (test_bit(__LINK_STATE_LINKWATCH_PENDING,
				     &dev->state)) {
				/* We must not have linkwatch events
				 * pending on unregister. If this
				 * happens, we simply run the queue
				 * unscheduled, resulting in a noop
				 * for this device.
				 */
				linkwatch_run_queue();
			}

			__rtnl_unlock();

			rebroadcast_time = jiffies;
		}

		msleep(250);

		if (time_after(jiffies, warning_time + 10 * HZ)) {
			printk(KERN_EMERG "unregister_netdevice: "
			       "waiting for %s to become free. Usage "
			       "count = %d\n",
			       dev->name, atomic_read(&dev->refcnt));
			warning_time = jiffies;
		}
	}
}

/* The sequence is:
 *
 *	rtnl_lock();
 *	...
 *	register_netdevice(x1);
 *	register_netdevice(x2);
 *	...
 *	unregister_netdevice(y1);
 *	unregister_netdevice(y2);
 *      ...
 *	rtnl_unlock();
 *	free_netdev(y1);
 *	free_netdev(y2);
 *
 * We are invoked by rtnl_unlock() after it drops the semaphore.
 * This allows us to deal with problems:
 * 1) We can create/delete sysfs objects which invoke hotplug
 *    without deadlocking with linkwatch via keventd.
 * 2) Since we run with the RTNL semaphore not held, we can sleep
 *    safely in order to wait for the netdev refcnt to drop to zero.
 */
static DECLARE_MUTEX(net_todo_run_mutex);
void netdev_run_todo(void)
{
	struct list_head list = LIST_HEAD_INIT(list);
	int err;


	/* Need to guard against multiple cpu's getting out of order. */
	down(&net_todo_run_mutex);

	/* Not safe to do outside the semaphore.  We must not return
	 * until all unregister events invoked by the local processor
	 * have been completed (either by this todo run, or one on
	 * another cpu).
	 */
	if (list_empty(&net_todo_list))
		goto out;

	/* Snapshot list, allow later requests */
	spin_lock(&net_todo_list_lock);
	list_splice_init(&net_todo_list, &list);
	spin_unlock(&net_todo_list_lock);
		
	while (!list_empty(&list)) {
		struct net_device *dev
			= list_entry(list.next, struct net_device, todo_list);
		list_del(&dev->todo_list);

		switch(dev->reg_state) {
		case NETREG_REGISTERING:
			err = netdev_register_sysfs(dev);
			if (err)
				printk(KERN_ERR "%s: failed sysfs registration (%d)\n",
				       dev->name, err);
			dev->reg_state = NETREG_REGISTERED;
			break;

		case NETREG_UNREGISTERING:
			netdev_unregister_sysfs(dev);
			dev->reg_state = NETREG_UNREGISTERED;

			netdev_wait_allrefs(dev);

			/* paranoia */
			BUG_ON(atomic_read(&dev->refcnt));
			BUG_TRAP(!dev->ip_ptr);
			BUG_TRAP(!dev->ip6_ptr);
			BUG_TRAP(!dev->dn_ptr);


			/* It must be the very last action, 
			 * after this 'dev' may point to freed up memory.
			 */
			if (dev->destructor)
				dev->destructor(dev);
			break;

		default:
			printk(KERN_ERR "network todo '%s' but state %d\n",
			       dev->name, dev->reg_state);
			break;
		}
	}

out:
	up(&net_todo_run_mutex);
}