dev.c

Linux Kernel 2.6.9 for OMAP1710

 *	dev_get	-	test if a device exists
 *	@name:	name to test for
 *
 *	Test if a name exists. Returns true if the name is found. In order
 *	to be sure the name is not allocated or removed during the test the
 *	caller must hold the rtnl semaphore.
 *
 *	This function exists only for back compatibility with older
 *	drivers.
 */
int __dev_get(const char *name)
{
	struct net_device *dev;

	read_lock(&dev_base_lock);
	dev = __dev_get_by_name(name);
	read_unlock(&dev_base_lock);
	return dev != NULL;
}

/**
 *	__dev_get_by_index - find a device by its ifindex
 *	@ifindex: index of device
 *
 *	Search for an interface by index. Returns %NULL if the device
 *	is not found or a pointer to the device. The device has not
 *	had its reference counter increased so the caller must be careful
 *	about locking. The caller must hold either the RTNL semaphore
 *	or @dev_base_lock.
 */

struct net_device *__dev_get_by_index(int ifindex)
{
	struct hlist_node *p;

	hlist_for_each(p, dev_index_hash(ifindex)) {
		struct net_device *dev
			= hlist_entry(p, struct net_device, index_hlist);
		if (dev->ifindex == ifindex)
			return dev;
	}
	return NULL;
}


/**
 *	dev_get_by_index - find a device by its ifindex
 *	@ifindex: index of device
 *
 *	Search for an interface by index. Returns NULL if the device
 *	is not found or a pointer to the device. The device returned has
 *	had a reference added and the pointer is safe until the user calls
 *	dev_put to indicate they have finished with it.
 */

struct net_device *dev_get_by_index(int ifindex)
{
	struct net_device *dev;

	read_lock(&dev_base_lock);
	dev = __dev_get_by_index(ifindex);
	if (dev)
		dev_hold(dev);
	read_unlock(&dev_base_lock);
	return dev;
}

/**
 *	dev_getbyhwaddr - find a device by its hardware address
 *	@type: media type of device
 *	@ha: hardware address
 *
 *	Search for an interface by MAC address. Returns NULL if the device
 *	is not found or a pointer to the device. The caller must hold the
 *	rtnl semaphore. The returned device has not had its ref count increased
 *	and the caller must therefore be careful about locking
 *
 *	BUGS:
 *	If the API was consistent this would be __dev_get_by_hwaddr
 */

struct net_device *dev_getbyhwaddr(unsigned short type, char *ha)
{
	struct net_device *dev;

	ASSERT_RTNL();

	for (dev = dev_base; dev; dev = dev->next)
		if (dev->type == type &&
		    !memcmp(dev->dev_addr, ha, dev->addr_len))
			break;
	return dev;
}

struct net_device *__dev_getfirstbyhwtype(unsigned short type)
{
	struct net_device *dev;

	for (dev = dev_base; dev; dev = dev->next)
		if (dev->type == type)
			break;
	return dev;
}

EXPORT_SYMBOL(__dev_getfirstbyhwtype);

struct net_device *dev_getfirstbyhwtype(unsigned short type)
{
	struct net_device *dev;

	rtnl_lock();
	dev = __dev_getfirstbyhwtype(type);
	if (dev)
		dev_hold(dev);
	rtnl_unlock();
	return dev;
}

EXPORT_SYMBOL(dev_getfirstbyhwtype);

/**
 *	dev_get_by_flags - find any device with given flags
 *	@if_flags: IFF_* values
 *	@mask: bitmask of bits in if_flags to check
 *
 *	Search for any interface with the given flags. Returns NULL if a device
 *	is not found or a pointer to the device. The device returned has 
 *	had a reference added and the pointer is safe until the user calls
 *	dev_put to indicate they have finished with it.
 */

struct net_device * dev_get_by_flags(unsigned short if_flags, unsigned short mask)
{
	struct net_device *dev;

	read_lock(&dev_base_lock);
	dev = __dev_get_by_flags(if_flags, mask);
	if (dev)
		dev_hold(dev);
	read_unlock(&dev_base_lock);
	return dev;
}

/**
 *	__dev_get_by_flags - find any device with given flags
 *	@if_flags: IFF_* values
 *	@mask: bitmask of bits in if_flags to check
 *
 *	Search for any interface with the given flags. Returns NULL if a device
 *	is not found or a pointer to the device. The caller must hold either
 *	the RTNL semaphore or @dev_base_lock.
 */

struct net_device *__dev_get_by_flags(unsigned short if_flags, unsigned short mask)
{
	struct net_device *dev;

	for (dev = dev_base; dev != NULL; dev = dev->next) {
		if (((dev->flags ^ if_flags) & mask) == 0)
			return dev;
	}
	return NULL;
}

/**
 *	dev_valid_name - check if name is okay for network device
 *	@name: name string
 *
 *	Network device names need to be valid file names to
 *	to allow sysfs to work
 */
int dev_valid_name(const char *name)
{
	return !(*name == '\0' 
		 || !strcmp(name, ".")
		 || !strcmp(name, "..")
		 || strchr(name, '/'));
}

/**
 *	dev_alloc_name - allocate a name for a device
 *	@dev: device
 *	@name: name format string
 *
 *	Passed a format string - eg "lt%d" it will try and find a suitable
 *	id. Not efficient for many devices, not called a lot. The caller
 *	must hold the dev_base or rtnl lock while allocating the name and
 *	adding the device in order to avoid duplicates. Returns the number
 *	of the unit assigned or a negative errno code.
 */

int dev_alloc_name(struct net_device *dev, const char *name)
{
	int i = 0;
	char buf[IFNAMSIZ];
	const char *p;
	const int max_netdevices = 8*PAGE_SIZE;
	long *inuse;
	struct net_device *d;

	p = strnchr(name, IFNAMSIZ-1, '%');
	if (p) {
		/*
		 * Verify the string as this thing may have come from
		 * the user.  There must be either one "%d" and no other "%"
		 * characters.
		 */
		if (p[1] != 'd' || strchr(p + 2, '%'))
			return -EINVAL;

		/* Use one page as a bit array of possible slots */
		inuse = (long *) get_zeroed_page(GFP_ATOMIC);
		if (!inuse)
			return -ENOMEM;

		for (d = dev_base; d; d = d->next) {
			if (!sscanf(d->name, name, &i))
				continue;
			if (i < 0 || i >= max_netdevices)
				continue;

			/*  avoid cases where sscanf is not exact inverse of printf */
			snprintf(buf, sizeof(buf), name, i);
			if (!strncmp(buf, d->name, IFNAMSIZ))
				set_bit(i, inuse);
		}

		i = find_first_zero_bit(inuse, max_netdevices);
		free_page((unsigned long) inuse);
	}

	snprintf(buf, sizeof(buf), name, i);
	if (!__dev_get_by_name(buf)) {
		strlcpy(dev->name, buf, IFNAMSIZ);
		return i;
	}

	/* It is possible to run out of possible slots
	 * when the name is long and there isn't enough space left
	 * for the digits, or if all bits are used.
	 */
	return -ENFILE;
}


/**
 *	dev_change_name - change name of a device
 *	@dev: device
 *	@newname: name (or format string) must be at least IFNAMSIZ
 *
 *	Change name of a device, can pass format strings "eth%d".
 *	for wildcarding.
 */
int dev_change_name(struct net_device *dev, char *newname)
{
	int err = 0;

	ASSERT_RTNL();

	if (dev->flags & IFF_UP)
		return -EBUSY;

	if (!dev_valid_name(newname))
		return -EINVAL;

	if (strchr(newname, '%')) {
		err = dev_alloc_name(dev, newname);
		if (err < 0)
			return err;
		strcpy(newname, dev->name);
	}
	else if (__dev_get_by_name(newname))
		return -EEXIST;
	else
		strlcpy(dev->name, newname, IFNAMSIZ);

	err = class_device_rename(&dev->class_dev, dev->name);
	if (!err) {
		hlist_del(&dev->name_hlist);
		hlist_add_head(&dev->name_hlist, dev_name_hash(dev->name));
		notifier_call_chain(&netdev_chain, NETDEV_CHANGENAME, dev);
	}

	return err;
}

/**
 *	netdev_state_change - device changes state
 *	@dev: device to cause notification
 *
 *	Called to indicate a device has changed state. This function calls
 *	the notifier chains for netdev_chain and sends a NEWLINK message
 *	to the routing socket.
 */
void netdev_state_change(struct net_device *dev)
{
	if (dev->flags & IFF_UP) {
		notifier_call_chain(&netdev_chain, NETDEV_CHANGE, dev);
		rtmsg_ifinfo(RTM_NEWLINK, dev, 0);
	}
}

/**
 *	dev_load 	- load a network module
 *	@name: name of interface
 *
 *	If a network interface is not present and the process has suitable
 *	privileges this function loads the module. If module loading is not
 *	available in this kernel then it becomes a nop.
 */

void dev_load(const char *name)
{
	struct net_device *dev;  

	read_lock(&dev_base_lock);
	dev = __dev_get_by_name(name);
	read_unlock(&dev_base_lock);

	if (!dev && capable(CAP_SYS_MODULE))
		request_module("%s", name);
}

static int default_rebuild_header(struct sk_buff *skb)
{
	printk(KERN_DEBUG "%s: default_rebuild_header called -- BUG!\n",
	       skb->dev ? skb->dev->name : "NULL!!!");
	kfree_skb(skb);
	return 1;
}


/**
 *	dev_open	- prepare an interface for use.
 *	@dev:	device to open
 *
 *	Takes a device from down to up state. The device's private open
 *	function is invoked and then the multicast lists are loaded. Finally
 *	the device is moved into the up state and a %NETDEV_UP message is
 *	sent to the netdev notifier chain.
 *
 *	Calling this function on an active interface is a nop. On a failure
 *	a negative errno code is returned.
 */
int dev_open(struct net_device *dev)
{
	int ret = 0;

	/*
	 *	Is it already up?
	 */

	if (dev->flags & IFF_UP)
		return 0;

	/*
	 *	Is it even present?
	 */
	if (!netif_device_present(dev))
		return -ENODEV;

	/*
	 *	Call device private open method
	 */
	set_bit(__LINK_STATE_START, &dev->state);
	if (dev->open) {
		ret = dev->open(dev);
		if (ret)
			clear_bit(__LINK_STATE_START, &dev->state);
	}

 	/*
	 *	If it went open OK then:
	 */

	if (!ret) {
		/*
		 *	Set the flags.
		 */
		dev->flags |= IFF_UP;

		/*
		 *	Initialize multicasting status
		 */
		dev_mc_upload(dev);

		/*
		 *	Wakeup transmit queue engine
		 */
		dev_activate(dev);

		/*
		 *	... and announce new interface.
		 */
		notifier_call_chain(&netdev_chain, NETDEV_UP, dev);
	}
	return ret;
}

/**
 *	dev_close - shutdown an interface.
 *	@dev: device to shutdown
 *
 *	This function moves an active device into down state. A
 *	%NETDEV_GOING_DOWN is sent to the netdev notifier chain. The device
 *	is then deactivated and finally a %NETDEV_DOWN is sent to the notifier
 *	chain.
 */
int dev_close(struct net_device *dev)
{
	if (!(dev->flags & IFF_UP))
		return 0;

	/*
	 *	Tell people we are going down, so that they can
	 *	prepare to death, when device is still operating.
	 */
	notifier_call_chain(&netdev_chain, NETDEV_GOING_DOWN, dev);

	dev_deactivate(dev);

	clear_bit(__LINK_STATE_START, &dev->state);

	/* Synchronize to scheduled poll. We cannot touch poll list,
	 * it can be even on different cpu. So just clear netif_running(),
	 * and wait when poll really will happen. Actually, the best place
	 * for this is inside dev->stop() after device stopped its irq
	 * engine, but this requires more changes in devices. */

	smp_mb__after_clear_bit(); /* Commit netif_running(). */
	while (test_bit(__LINK_STATE_RX_SCHED, &dev->state)) {
		/* No hurry. */
		current->state = TASK_INTERRUPTIBLE;
		schedule_timeout(1);
	}

	/*
	 *	Call the device specific close. This cannot fail.
	 *	Only if device is UP
	 *
	 *	We allow it to be called even after a DETACH hot-plug
	 *	event.
	 */
	if (dev->stop)
		dev->stop(dev);

	/*
	 *	Device is now down.
	 */

	dev->flags &= ~IFF_UP;

	/*
	 * Tell people we are down
	 */
	notifier_call_chain(&netdev_chain, NETDEV_DOWN, dev);

	return 0;
}


/*
 *	Device change register/unregister. These are not inline or static
 *	as we export them to the world.
 */

/**
 *	register_netdevice_notifier - register a network notifier block
 *	@nb: notifier
 *
 *	Register a notifier to be called when network device events occur.
 *	The notifier passed is linked into the kernel structures and must
 *	not be reused until it has been unregistered. A negative errno code
 *	is returned on a failure.
 *
 * 	When registered all registration and up events are replayed
 *	to the new notifier to allow device to have a race free 
 *	view of the network device list.
 */

int register_netdevice_notifier(struct notifier_block *nb)
{
	struct net_device *dev;
	int err;

	rtnl_lock();
	err = notifier_chain_register(&netdev_chain, nb);
	if (!err) {
		for (dev = dev_base; dev; dev = dev->next) {
			nb->notifier_call(nb, NETDEV_REGISTER, dev);

			if (dev->flags & IFF_UP) 
				nb->notifier_call(nb, NETDEV_UP, dev);
		}
	}
	rtnl_unlock();
	return err;
}

/**
 *	unregister_netdevice_notifier - unregister a network notifier block
 *	@nb: notifier
 *
 *	Unregister a notifier previously registered by
 *	register_netdevice_notifier(). The notifier is unlinked into the
 *	kernel structures and may then be reused. A negative errno code
 *	is returned on a failure.
 */

int unregister_netdevice_notifier(struct notifier_block *nb)
{
	return notifier_chain_unregister(&netdev_chain, nb);
}

/**
 *	call_netdevice_notifiers - call all network notifier blocks
 *      @val: value passed unmodified to notifier function
 *      @v:   pointer passed unmodified to notifier function
 *
 *	Call all network notifier blocks.  Parameters and return value
 *	are as for notifier_call_chain().
 */

int call_netdevice_notifiers(unsigned long val, void *v)
{
	return notifier_call_chain(&netdev_chain, val, v);
}

/*
 *	Support routine. Sends outgoing frames to any network
 *	taps currently in use.