[mirror_ubuntu-artful-kernel.git] / net / core / net_namespace.c

#include <linux/workqueue.h>
#include <linux/rtnetlink.h>
#include <linux/cache.h>
#include <linux/slab.h>
#include <linux/list.h>
#include <linux/delay.h>
#include <linux/sched.h>
#include <linux/idr.h>
#include <net/net_namespace.h>
#include <net/netns/generic.h>

/*
 *	Our network namespace constructor/destructor lists
 */

static LIST_HEAD(pernet_list);
static struct list_head *first_device = &pernet_list;
static DEFINE_MUTEX(net_mutex);

LIST_HEAD(net_namespace_list);
EXPORT_SYMBOL_GPL(net_namespace_list);

struct net init_net;
EXPORT_SYMBOL(init_net);

#define INITIAL_NET_GEN_PTRS	13 /* +1 for len +2 for rcu_head */

/*
 * setup_net runs the initializers for the network namespace object.
 */
static __net_init int setup_net(struct net *net)
{
	/* Must be called with net_mutex held */
	struct pernet_operations *ops;
	int error;
	struct net_generic *ng;

	atomic_set(&net->count, 1);
#ifdef NETNS_REFCNT_DEBUG
	atomic_set(&net->use_count, 0);
#endif

	error = -ENOMEM;
	ng = kzalloc(sizeof(struct net_generic) +
			INITIAL_NET_GEN_PTRS * sizeof(void *), GFP_KERNEL);
	if (ng == NULL)
		goto out;

	ng->len = INITIAL_NET_GEN_PTRS;
	INIT_RCU_HEAD(&ng->rcu);
	rcu_assign_pointer(net->gen, ng);

	error = 0;
	list_for_each_entry(ops, &pernet_list, list) {
		if (ops->init) {
			error = ops->init(net);
			if (error < 0)
				goto out_undo;
		}
	}
out:
	return error;

out_undo:
	/* Walk through the list backwards calling the exit functions
	 * for the pernet modules whose init functions did not fail.
	 */
	list_for_each_entry_continue_reverse(ops, &pernet_list, list) {
		if (ops->exit)
			ops->exit(net);
	}

	rcu_barrier();
	kfree(ng);
	goto out;
}

#ifdef CONFIG_NET_NS
static struct kmem_cache *net_cachep;
static struct workqueue_struct *netns_wq;

static struct net *net_alloc(void)
{
	return kmem_cache_zalloc(net_cachep, GFP_KERNEL);
}

static void net_free(struct net *net)
{
	if (!net)
		return;

#ifdef NETNS_REFCNT_DEBUG
	if (unlikely(atomic_read(&net->use_count) != 0)) {
		printk(KERN_EMERG "network namespace not free! Usage: %d\n",
			atomic_read(&net->use_count));
		return;
	}
#endif
	kfree(net->gen);
	kmem_cache_free(net_cachep, net);
}

struct net *copy_net_ns(unsigned long flags, struct net *old_net)
{
	struct net *new_net = NULL;
	int err;

	get_net(old_net);

	if (!(flags & CLONE_NEWNET))
		return old_net;

	err = -ENOMEM;
	new_net = net_alloc();
	if (!new_net)
		goto out;

	mutex_lock(&net_mutex);
	err = setup_net(new_net);
	if (err)
		goto out_unlock;

	rtnl_lock();
	list_add_tail(&new_net->list, &net_namespace_list);
	rtnl_unlock();


out_unlock:
	mutex_unlock(&net_mutex);
out:
	put_net(old_net);
	if (err) {
		net_free(new_net);
		new_net = ERR_PTR(err);
	}
	return new_net;
}

static void cleanup_net(struct work_struct *work)
{
	struct pernet_operations *ops;
	struct net *net;

	/* Be very certain incoming network packets will not find us */
	rcu_barrier();

	net = container_of(work, struct net, work);

	mutex_lock(&net_mutex);

	/* Don't let anyone else find us. */
	rtnl_lock();
	list_del(&net->list);
	rtnl_unlock();

	/* Run all of the network namespace exit methods */
	list_for_each_entry_reverse(ops, &pernet_list, list) {
		if (ops->exit)
			ops->exit(net);
	}

	mutex_unlock(&net_mutex);

	/* Ensure there are no outstanding rcu callbacks using this
	 * network namespace.
	 */
	rcu_barrier();

	/* Finally it is safe to free my network namespace structure */
	net_free(net);
}

void __put_net(struct net *net)
{
	/* Cleanup the network namespace in process context */
	INIT_WORK(&net->work, cleanup_net);
	queue_work(netns_wq, &net->work);
}
EXPORT_SYMBOL_GPL(__put_net);

#else
struct net *copy_net_ns(unsigned long flags, struct net *old_net)
{
	if (flags & CLONE_NEWNET)
		return ERR_PTR(-EINVAL);
	return old_net;
}
#endif

static int __init net_ns_init(void)
{
	int err;

	printk(KERN_INFO "net_namespace: %zd bytes\n", sizeof(struct net));
#ifdef CONFIG_NET_NS
	net_cachep = kmem_cache_create("net_namespace", sizeof(struct net),
					SMP_CACHE_BYTES,
					SLAB_PANIC, NULL);

	/* Create workqueue for cleanup */
	netns_wq = create_singlethread_workqueue("netns");
	if (!netns_wq)
		panic("Could not create netns workq");
#endif

	mutex_lock(&net_mutex);
	err = setup_net(&init_net);

	rtnl_lock();
	list_add_tail(&init_net.list, &net_namespace_list);
	rtnl_unlock();

	mutex_unlock(&net_mutex);
	if (err)
		panic("Could not setup the initial network namespace");

	return 0;
}

pure_initcall(net_ns_init);

#ifdef CONFIG_NET_NS
static int register_pernet_operations(struct list_head *list,
				      struct pernet_operations *ops)
{
	struct net *net, *undo_net;
	int error;

	list_add_tail(&ops->list, list);
	if (ops->init) {
		for_each_net(net) {
			error = ops->init(net);
			if (error)
				goto out_undo;
		}
	}
	return 0;

out_undo:
	/* If I have an error cleanup all namespaces I initialized */
	list_del(&ops->list);
	if (ops->exit) {
		for_each_net(undo_net) {
			if (undo_net == net)
				goto undone;
			ops->exit(undo_net);
		}
	}
undone:
	return error;
}

static void unregister_pernet_operations(struct pernet_operations *ops)
{
	struct net *net;

	list_del(&ops->list);
	if (ops->exit)
		for_each_net(net)
			ops->exit(net);
}

#else

static int register_pernet_operations(struct list_head *list,
				      struct pernet_operations *ops)
{
	if (ops->init == NULL)
		return 0;
	return ops->init(&init_net);
}

static void unregister_pernet_operations(struct pernet_operations *ops)
{
	if (ops->exit)
		ops->exit(&init_net);
}
#endif

static DEFINE_IDA(net_generic_ids);

/**
 *      register_pernet_subsys - register a network namespace subsystem
 *	@ops:  pernet operations structure for the subsystem
 *
 *	Register a subsystem which has init and exit functions
 *	that are called when network namespaces are created and
 *	destroyed respectively.
 *
 *	When registered all network namespace init functions are
 *	called for every existing network namespace.  Allowing kernel
 *	modules to have a race free view of the set of network namespaces.
 *
 *	When a new network namespace is created all of the init
 *	methods are called in the order in which they were registered.
 *
 *	When a network namespace is destroyed all of the exit methods
 *	are called in the reverse of the order with which they were
 *	registered.
 */
int register_pernet_subsys(struct pernet_operations *ops)
{
	int error;
	mutex_lock(&net_mutex);
	error =  register_pernet_operations(first_device, ops);
	mutex_unlock(&net_mutex);
	return error;
}
EXPORT_SYMBOL_GPL(register_pernet_subsys);

/**
 *      unregister_pernet_subsys - unregister a network namespace subsystem
 *	@ops: pernet operations structure to manipulate
 *
 *	Remove the pernet operations structure from the list to be
 *	used when network namespaces are created or destroyed.  In
 *	addition run the exit method for all existing network
 *	namespaces.
 */
void unregister_pernet_subsys(struct pernet_operations *module)
{
	mutex_lock(&net_mutex);
	unregister_pernet_operations(module);
	mutex_unlock(&net_mutex);
}
EXPORT_SYMBOL_GPL(unregister_pernet_subsys);

/**
 *      register_pernet_device - register a network namespace device
 *	@ops:  pernet operations structure for the subsystem
 *
 *	Register a device which has init and exit functions
 *	that are called when network namespaces are created and
 *	destroyed respectively.
 *
 *	When registered all network namespace init functions are
 *	called for every existing network namespace.  Allowing kernel
 *	modules to have a race free view of the set of network namespaces.
 *
 *	When a new network namespace is created all of the init
 *	methods are called in the order in which they were registered.
 *
 *	When a network namespace is destroyed all of the exit methods
 *	are called in the reverse of the order with which they were
 *	registered.
 */
int register_pernet_device(struct pernet_operations *ops)
{
	int error;
	mutex_lock(&net_mutex);
	error = register_pernet_operations(&pernet_list, ops);
	if (!error && (first_device == &pernet_list))
		first_device = &ops->list;
	mutex_unlock(&net_mutex);
	return error;
}
EXPORT_SYMBOL_GPL(register_pernet_device);

int register_pernet_gen_device(int *id, struct pernet_operations *ops)
{
	int error;
	mutex_lock(&net_mutex);
again:
	error = ida_get_new_above(&net_generic_ids, 1, id);
	if (error) {
		if (error == -EAGAIN) {
			ida_pre_get(&net_generic_ids, GFP_KERNEL);
			goto again;
		}
		goto out;
	}
	error = register_pernet_operations(&pernet_list, ops);
	if (error)
		ida_remove(&net_generic_ids, *id);
	else if (first_device == &pernet_list)
		first_device = &ops->list;
out:
	mutex_unlock(&net_mutex);
	return error;
}
EXPORT_SYMBOL_GPL(register_pernet_gen_device);

/**
 *      unregister_pernet_device - unregister a network namespace netdevice
 *	@ops: pernet operations structure to manipulate
 *
 *	Remove the pernet operations structure from the list to be
 *	used when network namespaces are created or destroyed.  In
 *	addition run the exit method for all existing network
 *	namespaces.
 */
void unregister_pernet_device(struct pernet_operations *ops)
{
	mutex_lock(&net_mutex);
	if (&ops->list == first_device)
		first_device = first_device->next;
	unregister_pernet_operations(ops);
	mutex_unlock(&net_mutex);
}
EXPORT_SYMBOL_GPL(unregister_pernet_device);

void unregister_pernet_gen_device(int id, struct pernet_operations *ops)
{
	mutex_lock(&net_mutex);
	if (&ops->list == first_device)
		first_device = first_device->next;
	unregister_pernet_operations(ops);
	ida_remove(&net_generic_ids, id);
	mutex_unlock(&net_mutex);
}
EXPORT_SYMBOL_GPL(unregister_pernet_gen_device);

static void net_generic_release(struct rcu_head *rcu)
{
	struct net_generic *ng;

	ng = container_of(rcu, struct net_generic, rcu);
	kfree(ng);
}

int net_assign_generic(struct net *net, int id, void *data)
{
	struct net_generic *ng, *old_ng;

	BUG_ON(!mutex_is_locked(&net_mutex));
	BUG_ON(id == 0);

	ng = old_ng = net->gen;
	if (old_ng->len >= id)
		goto assign;

	ng = kzalloc(sizeof(struct net_generic) +
			id * sizeof(void *), GFP_KERNEL);
	if (ng == NULL)
		return -ENOMEM;

	/*
	 * Some synchronisation notes:
	 *
	 * The net_generic explores the net->gen array inside rcu
	 * read section. Besides once set the net->gen->ptr[x]
	 * pointer never changes (see rules in netns/generic.h).
	 *
	 * That said, we simply duplicate this array and schedule
	 * the old copy for kfree after a grace period.
	 */

	ng->len = id;
	INIT_RCU_HEAD(&ng->rcu);
	memcpy(&ng->ptr, &old_ng->ptr, old_ng->len);

	rcu_assign_pointer(net->gen, ng);
	call_rcu(&old_ng->rcu, net_generic_release);
assign:
	ng->ptr[id - 1] = data;
	return 0;
}
EXPORT_SYMBOL_GPL(net_assign_generic);
Commit	Line	Data
5f256bec EB	1	#include <linux/workqueue.h>
	2	#include <linux/rtnetlink.h>
	3	#include <linux/cache.h>
	4	#include <linux/slab.h>
	5	#include <linux/list.h>
	6	#include <linux/delay.h>
9dd776b6	7	#include <linux/sched.h>
c93cf61f	8	#include <linux/idr.h>
5f256bec	9	#include <net/net_namespace.h>
dec827d1	10	#include <net/netns/generic.h>
5f256bec EB	11
	12	/*
	13	* Our network namespace constructor/destructor lists
	14	*/
	15
	16	static LIST_HEAD(pernet_list);
	17	static struct list_head *first_device = &pernet_list;
	18	static DEFINE_MUTEX(net_mutex);
	19
5f256bec	20	LIST_HEAD(net_namespace_list);
b76a461f	21	EXPORT_SYMBOL_GPL(net_namespace_list);
5f256bec	22
5f256bec	23	struct net init_net;
ff4b9502	24	EXPORT_SYMBOL(init_net);
5f256bec	25
dec827d1 PE	26	#define INITIAL_NET_GEN_PTRS 13 /* +1 for len +2 for rcu_head */
dec827d1 PE	27
5f256bec EB	28	/*
	29	* setup_net runs the initializers for the network namespace object.
	30	*/
1a2ee93d	31	static __net_init int setup_net(struct net *net)
5f256bec EB	32	{
	33	/* Must be called with net_mutex held */
	34	struct pernet_operations *ops;
5f256bec	35	int error;
dec827d1	36	struct net_generic *ng;
5f256bec	37
5f256bec	38	atomic_set(&net->count, 1);
5d1e4468	39	#ifdef NETNS_REFCNT_DEBUG
5f256bec	40	atomic_set(&net->use_count, 0);
5d1e4468	41	#endif
5f256bec	42
dec827d1 PE	43	error = -ENOMEM;
	44	ng = kzalloc(sizeof(struct net_generic) +
	45	INITIAL_NET_GEN_PTRS * sizeof(void *), GFP_KERNEL);
	46	if (ng == NULL)
	47	goto out;
	48
	49	ng->len = INITIAL_NET_GEN_PTRS;
	50	INIT_RCU_HEAD(&ng->rcu);
	51	rcu_assign_pointer(net->gen, ng);
	52
5f256bec	53	error = 0;
768f3591	54	list_for_each_entry(ops, &pernet_list, list) {
5f256bec EB	55	if (ops->init) {
	56	error = ops->init(net);
	57	if (error < 0)
	58	goto out_undo;
	59	}
	60	}
	61	out:
	62	return error;
768f3591	63
5f256bec EB	64	out_undo:
	65	/* Walk through the list backwards calling the exit functions
	66	* for the pernet modules whose init functions did not fail.
	67	*/
768f3591	68	list_for_each_entry_continue_reverse(ops, &pernet_list, list) {
5f256bec EB	69	if (ops->exit)
	70	ops->exit(net);
	71	}
310928d9 DL	72
310928d9 DL	73	rcu_barrier();
dec827d1	74	kfree(ng);
5f256bec EB	75	goto out;
	76	}
	77
6a1a3b9f	78	#ifdef CONFIG_NET_NS
d57a9212	79	static struct kmem_cache *net_cachep;
3ef1355d	80	static struct workqueue_struct *netns_wq;
d57a9212	81
6a1a3b9f PE	82	static struct net *net_alloc(void)
	83	{
	84	return kmem_cache_zalloc(net_cachep, GFP_KERNEL);
	85	}
	86
45a19b0a JFS	87	static void net_free(struct net *net)
	88	{
	89	if (!net)
	90	return;
	91
5d1e4468	92	#ifdef NETNS_REFCNT_DEBUG
45a19b0a JFS	93	if (unlikely(atomic_read(&net->use_count) != 0)) {
	94	printk(KERN_EMERG "network namespace not free! Usage: %d\n",
	95	atomic_read(&net->use_count));
	96	return;
	97	}
5d1e4468	98	#endif
4ef079cc	99	kfree(net->gen);
45a19b0a JFS	100	kmem_cache_free(net_cachep, net);
	101	}
	102
9dd776b6 EB	103	struct net copy_net_ns(unsigned long flags, struct net old_net)
	104	{
	105	struct net *new_net = NULL;
	106	int err;
	107
	108	get_net(old_net);
	109
	110	if (!(flags & CLONE_NEWNET))
	111	return old_net;
	112
9dd776b6 EB	113	err = -ENOMEM;
	114	new_net = net_alloc();
	115	if (!new_net)
	116	goto out;
	117
	118	mutex_lock(&net_mutex);
	119	err = setup_net(new_net);
	120	if (err)
	121	goto out_unlock;
	122
f4618d39	123	rtnl_lock();
9dd776b6	124	list_add_tail(&new_net->list, &net_namespace_list);
f4618d39	125	rtnl_unlock();
9dd776b6 EB	126
	127
	128	out_unlock:
	129	mutex_unlock(&net_mutex);
	130	out:
	131	put_net(old_net);
	132	if (err) {
	133	net_free(new_net);
	134	new_net = ERR_PTR(err);
	135	}
	136	return new_net;
	137	}
	138
6a1a3b9f PE	139	static void cleanup_net(struct work_struct *work)
	140	{
	141	struct pernet_operations *ops;
	142	struct net *net;
	143
b9f75f45 EB	144	/* Be very certain incoming network packets will not find us */
	145	rcu_barrier();
	146
6a1a3b9f PE	147	net = container_of(work, struct net, work);
	148
	149	mutex_lock(&net_mutex);
	150
	151	/* Don't let anyone else find us. */
	152	rtnl_lock();
	153	list_del(&net->list);
	154	rtnl_unlock();
	155
	156	/* Run all of the network namespace exit methods */
	157	list_for_each_entry_reverse(ops, &pernet_list, list) {
	158	if (ops->exit)
	159	ops->exit(net);
	160	}
	161
	162	mutex_unlock(&net_mutex);
	163
	164	/* Ensure there are no outstanding rcu callbacks using this
	165	* network namespace.
	166	*/
	167	rcu_barrier();
	168
	169	/* Finally it is safe to free my network namespace structure */
	170	net_free(net);
	171	}
	172
	173	void __put_net(struct net *net)
	174	{
	175	/* Cleanup the network namespace in process context */
	176	INIT_WORK(&net->work, cleanup_net);
3ef1355d	177	queue_work(netns_wq, &net->work);
6a1a3b9f PE	178	}
	179	EXPORT_SYMBOL_GPL(__put_net);
	180
	181	#else
	182	struct net copy_net_ns(unsigned long flags, struct net old_net)
	183	{
	184	if (flags & CLONE_NEWNET)
	185	return ERR_PTR(-EINVAL);
	186	return old_net;
	187	}
	188	#endif
	189
5f256bec EB	190	static int __init net_ns_init(void)
	191	{
	192	int err;
	193
	194	printk(KERN_INFO "net_namespace: %zd bytes\n", sizeof(struct net));
d57a9212	195	#ifdef CONFIG_NET_NS
5f256bec EB	196	net_cachep = kmem_cache_create("net_namespace", sizeof(struct net),
	197	SMP_CACHE_BYTES,
	198	SLAB_PANIC, NULL);
3ef1355d BT	199
	200	/* Create workqueue for cleanup */
	201	netns_wq = create_singlethread_workqueue("netns");
	202	if (!netns_wq)
	203	panic("Could not create netns workq");
d57a9212	204	#endif
3ef1355d	205
5f256bec EB	206	mutex_lock(&net_mutex);
	207	err = setup_net(&init_net);
	208
f4618d39	209	rtnl_lock();
5f256bec	210	list_add_tail(&init_net.list, &net_namespace_list);
f4618d39	211	rtnl_unlock();
5f256bec EB	212
	213	mutex_unlock(&net_mutex);
	214	if (err)
	215	panic("Could not setup the initial network namespace");
	216
	217	return 0;
	218	}
	219
	220	pure_initcall(net_ns_init);
	221
ed160e83	222	#ifdef CONFIG_NET_NS
5f256bec EB	223	static int register_pernet_operations(struct list_head *list,
	224	struct pernet_operations *ops)
	225	{
	226	struct net net, undo_net;
	227	int error;
	228
5f256bec	229	list_add_tail(&ops->list, list);
1dba323b PE	230	if (ops->init) {
1dba323b PE	231	for_each_net(net) {
5f256bec EB	232	error = ops->init(net);
	233	if (error)
	234	goto out_undo;
	235	}
	236	}
1dba323b	237	return 0;
5f256bec EB	238
	239	out_undo:
	240	/* If I have an error cleanup all namespaces I initialized */
	241	list_del(&ops->list);
1dba323b PE	242	if (ops->exit) {
	243	for_each_net(undo_net) {
	244	if (undo_net == net)
	245	goto undone;
5f256bec	246	ops->exit(undo_net);
1dba323b	247	}
5f256bec EB	248	}
5f256bec EB	249	undone:
1dba323b	250	return error;
5f256bec EB	251	}
	252
	253	static void unregister_pernet_operations(struct pernet_operations *ops)
	254	{
	255	struct net *net;
	256
	257	list_del(&ops->list);
1dba323b PE	258	if (ops->exit)
1dba323b PE	259	for_each_net(net)
5f256bec EB	260	ops->exit(net);
	261	}
	262
ed160e83 DL	263	#else
	264
	265	static int register_pernet_operations(struct list_head *list,
	266	struct pernet_operations *ops)
	267	{
	268	if (ops->init == NULL)
	269	return 0;
	270	return ops->init(&init_net);
	271	}
	272
	273	static void unregister_pernet_operations(struct pernet_operations *ops)
	274	{
	275	if (ops->exit)
	276	ops->exit(&init_net);
	277	}
	278	#endif
	279
c93cf61f PE	280	static DEFINE_IDA(net_generic_ids);
c93cf61f PE	281
5f256bec EB	282	/**
	283	* register_pernet_subsys - register a network namespace subsystem
	284	* @ops: pernet operations structure for the subsystem
	285	*
	286	* Register a subsystem which has init and exit functions
	287	* that are called when network namespaces are created and
	288	* destroyed respectively.
	289	*
	290	* When registered all network namespace init functions are
	291	* called for every existing network namespace. Allowing kernel
	292	* modules to have a race free view of the set of network namespaces.
	293	*
	294	* When a new network namespace is created all of the init
	295	* methods are called in the order in which they were registered.
	296	*
	297	* When a network namespace is destroyed all of the exit methods
	298	* are called in the reverse of the order with which they were
	299	* registered.
	300	*/
	301	int register_pernet_subsys(struct pernet_operations *ops)
	302	{
	303	int error;
	304	mutex_lock(&net_mutex);
	305	error = register_pernet_operations(first_device, ops);
	306	mutex_unlock(&net_mutex);
	307	return error;
	308	}
	309	EXPORT_SYMBOL_GPL(register_pernet_subsys);
	310
	311	/**
	312	* unregister_pernet_subsys - unregister a network namespace subsystem
	313	* @ops: pernet operations structure to manipulate
	314	*
	315	* Remove the pernet operations structure from the list to be
53379e57	316	* used when network namespaces are created or destroyed. In
5f256bec EB	317	* addition run the exit method for all existing network
	318	* namespaces.
	319	*/
	320	void unregister_pernet_subsys(struct pernet_operations *module)
	321	{
	322	mutex_lock(&net_mutex);
	323	unregister_pernet_operations(module);
	324	mutex_unlock(&net_mutex);
	325	}
	326	EXPORT_SYMBOL_GPL(unregister_pernet_subsys);
	327
	328	/**
	329	* register_pernet_device - register a network namespace device
	330	* @ops: pernet operations structure for the subsystem
	331	*
	332	* Register a device which has init and exit functions
	333	* that are called when network namespaces are created and
	334	* destroyed respectively.
	335	*
	336	* When registered all network namespace init functions are
	337	* called for every existing network namespace. Allowing kernel
	338	* modules to have a race free view of the set of network namespaces.
	339	*
	340	* When a new network namespace is created all of the init
	341	* methods are called in the order in which they were registered.
	342	*
	343	* When a network namespace is destroyed all of the exit methods
	344	* are called in the reverse of the order with which they were
	345	* registered.
	346	*/
	347	int register_pernet_device(struct pernet_operations *ops)
	348	{
	349	int error;
	350	mutex_lock(&net_mutex);
	351	error = register_pernet_operations(&pernet_list, ops);
	352	if (!error && (first_device == &pernet_list))
	353	first_device = &ops->list;
	354	mutex_unlock(&net_mutex);
	355	return error;
	356	}
	357	EXPORT_SYMBOL_GPL(register_pernet_device);
	358
c93cf61f PE	359	int register_pernet_gen_device(int id, struct pernet_operations ops)
	360	{
	361	int error;
	362	mutex_lock(&net_mutex);
	363	again:
	364	error = ida_get_new_above(&net_generic_ids, 1, id);
	365	if (error) {
	366	if (error == -EAGAIN) {
	367	ida_pre_get(&net_generic_ids, GFP_KERNEL);
	368	goto again;
	369	}
	370	goto out;
	371	}
	372	error = register_pernet_operations(&pernet_list, ops);
	373	if (error)
	374	ida_remove(&net_generic_ids, *id);
	375	else if (first_device == &pernet_list)
	376	first_device = &ops->list;
	377	out:
	378	mutex_unlock(&net_mutex);
	379	return error;
	380	}
	381	EXPORT_SYMBOL_GPL(register_pernet_gen_device);
	382
5f256bec EB	383	/**
	384	* unregister_pernet_device - unregister a network namespace netdevice
	385	* @ops: pernet operations structure to manipulate
	386	*
	387	* Remove the pernet operations structure from the list to be
53379e57	388	* used when network namespaces are created or destroyed. In
5f256bec EB	389	* addition run the exit method for all existing network
	390	* namespaces.
	391	*/
	392	void unregister_pernet_device(struct pernet_operations *ops)
	393	{
	394	mutex_lock(&net_mutex);
	395	if (&ops->list == first_device)
	396	first_device = first_device->next;
	397	unregister_pernet_operations(ops);
	398	mutex_unlock(&net_mutex);
	399	}
	400	EXPORT_SYMBOL_GPL(unregister_pernet_device);
c93cf61f PE	401
	402	void unregister_pernet_gen_device(int id, struct pernet_operations *ops)
	403	{
	404	mutex_lock(&net_mutex);
	405	if (&ops->list == first_device)
	406	first_device = first_device->next;
	407	unregister_pernet_operations(ops);
	408	ida_remove(&net_generic_ids, id);
	409	mutex_unlock(&net_mutex);
	410	}
	411	EXPORT_SYMBOL_GPL(unregister_pernet_gen_device);
dec827d1 PE	412
	413	static void net_generic_release(struct rcu_head *rcu)
	414	{
	415	struct net_generic *ng;
	416
	417	ng = container_of(rcu, struct net_generic, rcu);
	418	kfree(ng);
	419	}
	420
	421	int net_assign_generic(struct net net, int id, void data)
	422	{
	423	struct net_generic ng, old_ng;
	424
	425	BUG_ON(!mutex_is_locked(&net_mutex));
	426	BUG_ON(id == 0);
	427
	428	ng = old_ng = net->gen;
	429	if (old_ng->len >= id)
	430	goto assign;
	431
	432	ng = kzalloc(sizeof(struct net_generic) +
	433	id * sizeof(void *), GFP_KERNEL);
	434	if (ng == NULL)
	435	return -ENOMEM;
	436
	437	/*
	438	* Some synchronisation notes:
	439	*
	440	* The net_generic explores the net->gen array inside rcu
	441	* read section. Besides once set the net->gen->ptr[x]
	442	* pointer never changes (see rules in netns/generic.h).
	443	*
	444	* That said, we simply duplicate this array and schedule
	445	* the old copy for kfree after a grace period.
	446	*/
	447
	448	ng->len = id;
	449	INIT_RCU_HEAD(&ng->rcu);
	450	memcpy(&ng->ptr, &old_ng->ptr, old_ng->len);
	451
	452	rcu_assign_pointer(net->gen, ng);
	453	call_rcu(&old_ng->rcu, net_generic_release);
	454	assign:
	455	ng->ptr[id - 1] = data;
	456	return 0;
	457	}
	458	EXPORT_SYMBOL_GPL(net_assign_generic);