dev.c

/**
 *	synchronize_net -  Synchronize with packet receive processing
 *
 *	Wait for packets currently being received to be done.
 *	Does not block later packets from starting.
 */
void synchronize_net(void)
{
	might_sleep();
	if (rtnl_is_locked())
		synchronize_rcu_expedited();
	else
		synchronize_rcu();
}
EXPORT_SYMBOL(synchronize_net);

/**
 *	unregister_netdevice_queue - remove device from the kernel
 *	@dev: device
 *	@head: list
 *
 *	This function shuts down a device interface and removes it
 *	from the kernel tables.
 *	If head not NULL, device is queued to be unregistered later.
 *
 *	Callers must hold the rtnl semaphore.  You may want
 *	unregister_netdev() instead of this.
 */

void unregister_netdevice_queue(struct net_device *dev, struct list_head *head)
{
	ASSERT_RTNL();

	if (head) {
		list_move_tail(&dev->unreg_list, head);
	} else {
		rollback_registered(dev);
		/* Finish processing unregister after unlock */
		net_set_todo(dev);
	}
}
EXPORT_SYMBOL(unregister_netdevice_queue);

/**
 *	unregister_netdevice_many - unregister many devices
 *	@head: list of devices
 */
void unregister_netdevice_many(struct list_head *head)
{
	struct net_device *dev;

	if (!list_empty(head)) {
		rollback_registered_many(head);
		list_for_each_entry(dev, head, unreg_list)
			net_set_todo(dev);
	}
}
EXPORT_SYMBOL(unregister_netdevice_many);

/**
 *	unregister_netdev - remove device from the kernel
 *	@dev: device
 *
 *	This function shuts down a device interface and removes it
 *	from the kernel tables.
 *
 *	This is just a wrapper for unregister_netdevice that takes
 *	the rtnl semaphore.  In general you want to use this and not
 *	unregister_netdevice.
 */
void unregister_netdev(struct net_device *dev)
{
	rtnl_lock();
	unregister_netdevice(dev);
	rtnl_unlock();
}
EXPORT_SYMBOL(unregister_netdev);

/**
 *	dev_change_net_namespace - move device to different nethost namespace
 *	@dev: device
 *	@net: network namespace
 *	@pat: If not NULL name pattern to try if the current device name
 *	      is already taken in the destination network namespace.
 *
 *	This function shuts down a device interface and moves it
 *	to a new network namespace. On success 0 is returned, on
 *	a failure a netagive errno code is returned.
 *
 *	Callers must hold the rtnl semaphore.
 */

int dev_change_net_namespace(struct net_device *dev, struct net *net, const char *pat)
{
	int err;

	ASSERT_RTNL();

	/* Don't allow namespace local devices to be moved. */
	err = -EINVAL;
	if (dev->features & NETIF_F_NETNS_LOCAL)
		goto out;

	/* Ensure the device has been registrered */
	err = -EINVAL;
	if (dev->reg_state != NETREG_REGISTERED)
		goto out;

	/* Get out if there is nothing todo */
	err = 0;
	if (net_eq(dev_net(dev), net))
		goto out;

	/* Pick the destination device name, and ensure
	 * we can use it in the destination network namespace.
	 */
	err = -EEXIST;
	if (__dev_get_by_name(net, dev->name)) {
		/* We get here if we can't use the current device name */
		if (!pat)
			goto out;
		if (dev_get_valid_name(dev, pat) < 0)
			goto out;
	}

	/*
	 * And now a mini version of register_netdevice unregister_netdevice.
	 */

	/* If device is running close it first. */
	dev_close(dev);

	/* And unlink it from device chain */
	err = -ENODEV;
	unlist_netdevice(dev);

	synchronize_net();

	/* Shutdown queueing discipline. */
	dev_shutdown(dev);

	/* Notify protocols, that we are about to destroy
	   this device. They should clean all the things.

	   Note that dev->reg_state stays at NETREG_REGISTERED.
	   This is wanted because this way 8021q and macvlan know
	   the device is just moving and can keep their slaves up.
	*/
	call_netdevice_notifiers(NETDEV_UNREGISTER, dev);
	call_netdevice_notifiers(NETDEV_UNREGISTER_BATCH, dev);

	/*
	 *	Flush the unicast and multicast chains
	 */
	dev_uc_flush(dev);
	dev_mc_flush(dev);

	/* Actually switch the network namespace */
	dev_net_set(dev, net);

	/* If there is an ifindex conflict assign a new one */
	if (__dev_get_by_index(net, dev->ifindex)) {
		int iflink = (dev->iflink == dev->ifindex);
		dev->ifindex = dev_new_index(net);
		if (iflink)
			dev->iflink = dev->ifindex;
	}

	/* Fixup kobjects */
	err = device_rename(&dev->dev, dev->name);
	WARN_ON(err);

	/* Add the device back in the hashes */
	list_netdevice(dev);

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

	/*
	 *	Prevent userspace races by waiting until the network
	 *	device is fully setup before sending notifications.
	 */
	rtmsg_ifinfo(RTM_NEWLINK, dev, ~0U);

	synchronize_net();
	err = 0;
out:
	return err;
}
EXPORT_SYMBOL_GPL(dev_change_net_namespace);

static int dev_cpu_callback(struct notifier_block *nfb,
			    unsigned long action,
			    void *ocpu)
{
	struct sk_buff **list_skb;
	struct sk_buff *skb;
	unsigned int cpu, oldcpu = (unsigned long)ocpu;
	struct softnet_data *sd, *oldsd;

	if (action != CPU_DEAD && action != CPU_DEAD_FROZEN)
		return NOTIFY_OK;

	local_irq_disable();
	cpu = smp_processor_id();
	sd = &per_cpu(softnet_data, cpu);
	oldsd = &per_cpu(softnet_data, oldcpu);

	/* Find end of our completion_queue. */
	list_skb = &sd->completion_queue;
	while (*list_skb)
		list_skb = &(*list_skb)->next;
	/* Append completion queue from offline CPU. */
	*list_skb = oldsd->completion_queue;
	oldsd->completion_queue = NULL;

	/* Append output queue from offline CPU. */
	if (oldsd->output_queue) {
		*sd->output_queue_tailp = oldsd->output_queue;
		sd->output_queue_tailp = oldsd->output_queue_tailp;
		oldsd->output_queue = NULL;
		oldsd->output_queue_tailp = &oldsd->output_queue;
	}
	/* Append NAPI poll list from offline CPU. */
	if (!list_empty(&oldsd->poll_list)) {
		list_splice_init(&oldsd->poll_list, &sd->poll_list);
		raise_softirq_irqoff(NET_RX_SOFTIRQ);
	}

	raise_softirq_irqoff(NET_TX_SOFTIRQ);
	local_irq_enable();

	/* Process offline CPU's input_pkt_queue */
	while ((skb = __skb_dequeue(&oldsd->process_queue))) {
		netif_rx(skb);
		input_queue_head_incr(oldsd);
	}
	while ((skb = __skb_dequeue(&oldsd->input_pkt_queue))) {
		netif_rx(skb);
		input_queue_head_incr(oldsd);
	}

	return NOTIFY_OK;
}


/**
 *	netdev_increment_features - increment feature set by one
 *	@all: current feature set
 *	@one: new feature set
 *	@mask: mask feature set
 *
 *	Computes a new feature set after adding a device with feature set
 *	@one to the master device with current feature set @all.  Will not
 *	enable anything that is off in @mask. Returns the new feature set.
 */
u32 netdev_increment_features(u32 all, u32 one, u32 mask)
{
	if (mask & NETIF_F_GEN_CSUM)
		mask |= NETIF_F_ALL_CSUM;
	mask |= NETIF_F_VLAN_CHALLENGED;

	all |= one & (NETIF_F_ONE_FOR_ALL|NETIF_F_ALL_CSUM) & mask;
	all &= one | ~NETIF_F_ALL_FOR_ALL;

	/* If device needs checksumming, downgrade to it. */
	if (all & (NETIF_F_ALL_CSUM & ~NETIF_F_NO_CSUM))
		all &= ~NETIF_F_NO_CSUM;

	/* If one device supports hw checksumming, set for all. */
	if (all & NETIF_F_GEN_CSUM)
		all &= ~(NETIF_F_ALL_CSUM & ~NETIF_F_GEN_CSUM);

	return all;
}
EXPORT_SYMBOL(netdev_increment_features);

static struct hlist_head *netdev_create_hash(void)
{
	int i;
	struct hlist_head *hash;

	hash = kmalloc(sizeof(*hash) * NETDEV_HASHENTRIES, GFP_KERNEL);
	if (hash != NULL)
		for (i = 0; i < NETDEV_HASHENTRIES; i++)
			INIT_HLIST_HEAD(&hash[i]);

	return hash;
}

/* Initialize per network namespace state */
static int __net_init netdev_init(struct net *net)
{
	INIT_LIST_HEAD(&net->dev_base_head);

	net->dev_name_head = netdev_create_hash();
	if (net->dev_name_head == NULL)
		goto err_name;

	net->dev_index_head = netdev_create_hash();
	if (net->dev_index_head == NULL)
		goto err_idx;

	return 0;

err_idx:
	kfree(net->dev_name_head);
err_name:
	return -ENOMEM;
}

/**
 *	netdev_drivername - network driver for the device
 *	@dev: network device
 *
 *	Determine network driver for device.
 */
const char *netdev_drivername(const struct net_device *dev)
{
	const struct device_driver *driver;
	const struct device *parent;
	const char *empty = "";

	parent = dev->dev.parent;
	if (!parent)
		return empty;

	driver = parent->driver;
	if (driver && driver->name)
		return driver->name;
	return empty;
}

static int __netdev_printk(const char *level, const struct net_device *dev,
			   struct va_format *vaf)
{
	int r;

	if (dev && dev->dev.parent)
		r = dev_printk(level, dev->dev.parent, "%s: %pV",
			       netdev_name(dev), vaf);
	else if (dev)
		r = printk("%s%s: %pV", level, netdev_name(dev), vaf);
	else
		r = printk("%s(NULL net_device): %pV", level, vaf);

	return r;
}

int netdev_printk(const char *level, const struct net_device *dev,
		  const char *format, ...)
{
	struct va_format vaf;
	va_list args;
	int r;

	va_start(args, format);

	vaf.fmt = format;
	vaf.va = &args;

	r = __netdev_printk(level, dev, &vaf);
	va_end(args);

	return r;
}
EXPORT_SYMBOL(netdev_printk);

#define define_netdev_printk_level(func, level)			\
int func(const struct net_device *dev, const char *fmt, ...)	\
{								\
	int r;							\
	struct va_format vaf;					\
	va_list args;						\
								\
	va_start(args, fmt);					\
								\
	vaf.fmt = fmt;						\
	vaf.va = &args;						\
								\
	r = __netdev_printk(level, dev, &vaf);			\
	va_end(args);						\
								\
	return r;						\
}								\
EXPORT_SYMBOL(func);

define_netdev_printk_level(netdev_emerg, KERN_EMERG);
define_netdev_printk_level(netdev_alert, KERN_ALERT);
define_netdev_printk_level(netdev_crit, KERN_CRIT);
define_netdev_printk_level(netdev_err, KERN_ERR);
define_netdev_printk_level(netdev_warn, KERN_WARNING);
define_netdev_printk_level(netdev_notice, KERN_NOTICE);
define_netdev_printk_level(netdev_info, KERN_INFO);

static void __net_exit netdev_exit(struct net *net)
{
	kfree(net->dev_name_head);
	kfree(net->dev_index_head);
}

static struct pernet_operations __net_initdata netdev_net_ops = {
	.init = netdev_init,
	.exit = netdev_exit,
};

static void __net_exit default_device_exit(struct net *net)
{
	struct net_device *dev, *aux;
	/*
	 * Push all migratable network devices back to the
	 * initial network namespace
	 */
	rtnl_lock();
	for_each_netdev_safe(net, dev, aux) {
		int err;
		char fb_name[IFNAMSIZ];

		/* Ignore unmoveable devices (i.e. loopback) */
		if (dev->features & NETIF_F_NETNS_LOCAL)
			continue;

		/* Leave virtual devices for the generic cleanup */
		if (dev->rtnl_link_ops)
			continue;

		/* Push remaining network devices to init_net */
		snprintf(fb_name, IFNAMSIZ, "dev%d", dev->ifindex);
		err = dev_change_net_namespace(dev, &init_net, fb_name);
		if (err) {
			printk(KERN_EMERG "%s: failed to move %s to init_net: %d\n",
				__func__, dev->name, err);
			BUG();
		}
	}
	rtnl_unlock();
}

static void __net_exit default_device_exit_batch(struct list_head *net_list)
{
	/* At exit all network devices most be removed from a network
	 * namespace.  Do this in the reverse order of registration.
	 * Do this across as many network namespaces as possible to
	 * improve batching efficiency.
	 */
	struct net_device *dev;
	struct net *net;
	LIST_HEAD(dev_kill_list);

	rtnl_lock();
	list_for_each_entry(net, net_list, exit_list) {
		for_each_netdev_reverse(net, dev) {
			if (dev->rtnl_link_ops)
				dev->rtnl_link_ops->dellink(dev, &dev_kill_list);
			else
				unregister_netdevice_queue(dev, &dev_kill_list);
		}
	}
	unregister_netdevice_many(&dev_kill_list);
	list_del(&dev_kill_list);
	rtnl_unlock();
}

static struct pernet_operations __net_initdata default_device_ops = {
	.exit = default_device_exit,
	.exit_batch = default_device_exit_batch,
};

/*
 *	Initialize the DEV module. At boot time this walks the device list and
 *	unhooks any devices that fail to initialise (normally hardware not
 *	present) and leaves us with a valid list of present and active devices.
 *
 */

/*
 *       This is called single threaded during boot, so no need
 *       to take the rtnl semaphore.
 */
static int __init net_dev_init(void)
{
	int i, rc = -ENOMEM;

	BUG_ON(!dev_boot_phase);

	if (dev_proc_init())
		goto out;

	if (netdev_kobject_init())
		goto out;

	INIT_LIST_HEAD(&ptype_all);
	for (i = 0; i < PTYPE_HASH_SIZE; i++)
		INIT_LIST_HEAD(&ptype_base[i]);

	if (register_pernet_subsys(&netdev_net_ops))
		goto out;

	/*
	 *	Initialise the packet receive queues.
	 */

	for_each_possible_cpu(i) {
		struct softnet_data *sd = &per_cpu(softnet_data, i);

		memset(sd, 0, sizeof(*sd));
		skb_queue_head_init(&sd->input_pkt_queue);
		skb_queue_head_init(&sd->process_queue);
		sd->completion_queue = NULL;
		INIT_LIST_HEAD(&sd->poll_list);
		sd->output_queue = NULL;
		sd->output_queue_tailp = &sd->output_queue;
#ifdef CONFIG_RPS
		sd->csd.func = rps_trigger_softirq;
		sd->csd.info = sd;
		sd->csd.flags = 0;
		sd->cpu = i;
#endif

		sd->backlog.poll = process_backlog;
		sd->backlog.weight = weight_p;
		sd->backlog.gro_list = NULL;
		sd->backlog.gro_count = 0;
	}

	dev_boot_phase = 0;

	/* The loopback device is special if any other network devices
	 * is present in a network namespace the loopback device must
	 * be present. Since we now dynamically allocate and free the
	 * loopback device ensure this invariant is maintained by
	 * keeping the loopback device as the first device on the
	 * list of network devices.  Ensuring the loopback devices
	 * is the first device that appears and the last network device
	 * that disappears.
	 */
	if (register_pernet_device(&loopback_net_ops))
		goto out;

	if (register_pernet_device(&default_device_ops))
		goto out;

	open_softirq(NET_TX_SOFTIRQ, net_tx_action);
	open_softirq(NET_RX_SOFTIRQ, net_rx_action);

	hotcpu_notifier(dev_cpu_callback, 0);
	dst_init();
	dev_mcast_init();
	rc = 0;
out:
	return rc;
}

subsys_initcall(net_dev_init);

static int __init initialize_hashrnd(void)
{
	get_random_bytes(&hashrnd, sizeof(hashrnd));
	return 0;
}

late_initcall_sync(initialize_hashrnd);