[deliverable/linux.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 = 0;

	atomic_set(&net->count, 1);

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

	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();
	goto out;
}

static struct net_generic *net_alloc_generic(void)
{
	struct net_generic *ng;
	size_t generic_size = sizeof(struct net_generic) +
		INITIAL_NET_GEN_PTRS * sizeof(void *);

	ng = kzalloc(generic_size, GFP_KERNEL);
	if (ng)
		ng->len = INITIAL_NET_GEN_PTRS;

	return ng;
}

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

static struct net *net_alloc(void)
{
	struct net *net = NULL;
	struct net_generic *ng;

	ng = net_alloc_generic();
	if (!ng)
		goto out;

	net = kmem_cache_zalloc(net_cachep, GFP_KERNEL);
	if (!net)
		goto out_free;

	rcu_assign_pointer(net->gen, ng);
out:
	return net;

out_free:
	kfree(ng);
	goto out;
}

static void net_free(struct net *net)
{
#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_err;

	mutex_lock(&net_mutex);
	err = setup_net(new_net);
	if (!err) {
		rtnl_lock();
		list_add_tail(&new_net->list, &net_namespace_list);
		rtnl_unlock();
	}
	mutex_unlock(&net_mutex);

	if (err)
		goto out_free;
out:
	put_net(old_net);
	return new_net;

out_free:
	net_free(new_net);
out_err:
	new_net = ERR_PTR(err);
	goto out;
}

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

	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)
{
	struct net_generic *ng;
	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

	ng = net_alloc_generic();
	if (!ng)
		panic("Could not allocate generic netns");

	rcu_assign_pointer(init_net.gen, ng);

	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);

int register_pernet_gen_subsys(int *id, struct pernet_operations *ops)
{
	int rv;

	mutex_lock(&net_mutex);
again:
	rv = ida_get_new_above(&net_generic_ids, 1, id);
	if (rv < 0) {
		if (rv == -EAGAIN) {
			ida_pre_get(&net_generic_ids, GFP_KERNEL);
			goto again;
		}
		goto out;
	}
	rv = register_pernet_operations(first_device, ops);
	if (rv < 0)
		ida_remove(&net_generic_ids, *id);
out:
	mutex_unlock(&net_mutex);
	return rv;
}
EXPORT_SYMBOL_GPL(register_pernet_gen_subsys);

void unregister_pernet_gen_subsys(int id, struct pernet_operations *ops)
{
	mutex_lock(&net_mutex);
	unregister_pernet_operations(ops);
	ida_remove(&net_generic_ids, id);
	mutex_unlock(&net_mutex);
}
EXPORT_SYMBOL_GPL(unregister_pernet_gen_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;
	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;
486a87f1	35	int error = 0;
5f256bec	36
5f256bec	37	atomic_set(&net->count, 1);
486a87f1	38
5d1e4468	39	#ifdef NETNS_REFCNT_DEBUG
5f256bec	40	atomic_set(&net->use_count, 0);
5d1e4468	41	#endif
5f256bec	42
768f3591	43	list_for_each_entry(ops, &pernet_list, list) {
5f256bec EB	44	if (ops->init) {
	45	error = ops->init(net);
	46	if (error < 0)
	47	goto out_undo;
	48	}
	49	}
	50	out:
	51	return error;
768f3591	52
5f256bec EB	53	out_undo:
	54	/* Walk through the list backwards calling the exit functions
	55	* for the pernet modules whose init functions did not fail.
	56	*/
768f3591	57	list_for_each_entry_continue_reverse(ops, &pernet_list, list) {
5f256bec EB	58	if (ops->exit)
	59	ops->exit(net);
	60	}
310928d9 DL	61
310928d9 DL	62	rcu_barrier();
5f256bec EB	63	goto out;
	64	}
	65
486a87f1	66	static struct net_generic *net_alloc_generic(void)
6a1a3b9f	67	{
486a87f1 DL	68	struct net_generic *ng;
	69	size_t generic_size = sizeof(struct net_generic) +
	70	INITIAL_NET_GEN_PTRS * sizeof(void *);
	71
	72	ng = kzalloc(generic_size, GFP_KERNEL);
	73	if (ng)
	74	ng->len = INITIAL_NET_GEN_PTRS;
	75
	76	return ng;
6a1a3b9f PE	77	}
6a1a3b9f PE	78
ebe47d47 CN	79	#ifdef CONFIG_NET_NS
	80	static struct kmem_cache *net_cachep;
	81	static struct workqueue_struct *netns_wq;
	82
486a87f1	83	static struct net *net_alloc(void)
45a19b0a	84	{
486a87f1 DL	85	struct net *net = NULL;
	86	struct net_generic *ng;
	87
	88	ng = net_alloc_generic();
	89	if (!ng)
	90	goto out;
	91
	92	net = kmem_cache_zalloc(net_cachep, GFP_KERNEL);
45a19b0a	93	if (!net)
486a87f1	94	goto out_free;
45a19b0a	95
486a87f1 DL	96	rcu_assign_pointer(net->gen, ng);
	97	out:
	98	return net;
	99
	100	out_free:
	101	kfree(ng);
	102	goto out;
	103	}
	104
	105	static void net_free(struct net *net)
	106	{
5d1e4468	107	#ifdef NETNS_REFCNT_DEBUG
45a19b0a JFS	108	if (unlikely(atomic_read(&net->use_count) != 0)) {
	109	printk(KERN_EMERG "network namespace not free! Usage: %d\n",
	110	atomic_read(&net->use_count));
	111	return;
	112	}
5d1e4468	113	#endif
4ef079cc	114	kfree(net->gen);
45a19b0a JFS	115	kmem_cache_free(net_cachep, net);
	116	}
	117
9dd776b6 EB	118	struct net copy_net_ns(unsigned long flags, struct net old_net)
	119	{
	120	struct net *new_net = NULL;
	121	int err;
	122
	123	get_net(old_net);
	124
	125	if (!(flags & CLONE_NEWNET))
	126	return old_net;
	127
9dd776b6 EB	128	err = -ENOMEM;
	129	new_net = net_alloc();
	130	if (!new_net)
486a87f1	131	goto out_err;
9dd776b6 EB	132
	133	mutex_lock(&net_mutex);
	134	err = setup_net(new_net);
486a87f1 DL	135	if (!err) {
	136	rtnl_lock();
	137	list_add_tail(&new_net->list, &net_namespace_list);
	138	rtnl_unlock();
	139	}
9dd776b6	140	mutex_unlock(&net_mutex);
486a87f1 DL	141
	142	if (err)
	143	goto out_free;
9dd776b6 EB	144	out:
9dd776b6 EB	145	put_net(old_net);
9dd776b6	146	return new_net;
486a87f1 DL	147
	148	out_free:
	149	net_free(new_net);
	150	out_err:
	151	new_net = ERR_PTR(err);
	152	goto out;
9dd776b6 EB	153	}
9dd776b6 EB	154
6a1a3b9f PE	155	static void cleanup_net(struct work_struct *work)
	156	{
	157	struct pernet_operations *ops;
	158	struct net *net;
	159
	160	net = container_of(work, struct net, work);
	161
	162	mutex_lock(&net_mutex);
	163
	164	/* Don't let anyone else find us. */
	165	rtnl_lock();
	166	list_del(&net->list);
	167	rtnl_unlock();
	168
	169	/* Run all of the network namespace exit methods */
	170	list_for_each_entry_reverse(ops, &pernet_list, list) {
	171	if (ops->exit)
	172	ops->exit(net);
	173	}
	174
	175	mutex_unlock(&net_mutex);
	176
	177	/* Ensure there are no outstanding rcu callbacks using this
	178	* network namespace.
	179	*/
	180	rcu_barrier();
	181
	182	/* Finally it is safe to free my network namespace structure */
	183	net_free(net);
	184	}
	185
	186	void __put_net(struct net *net)
	187	{
	188	/* Cleanup the network namespace in process context */
	189	INIT_WORK(&net->work, cleanup_net);
3ef1355d	190	queue_work(netns_wq, &net->work);
6a1a3b9f PE	191	}
	192	EXPORT_SYMBOL_GPL(__put_net);
	193
	194	#else
	195	struct net copy_net_ns(unsigned long flags, struct net old_net)
	196	{
	197	if (flags & CLONE_NEWNET)
	198	return ERR_PTR(-EINVAL);
	199	return old_net;
	200	}
	201	#endif
	202
5f256bec EB	203	static int __init net_ns_init(void)
5f256bec EB	204	{
486a87f1	205	struct net_generic *ng;
5f256bec EB	206	int err;
	207
	208	printk(KERN_INFO "net_namespace: %zd bytes\n", sizeof(struct net));
d57a9212	209	#ifdef CONFIG_NET_NS
5f256bec EB	210	net_cachep = kmem_cache_create("net_namespace", sizeof(struct net),
	211	SMP_CACHE_BYTES,
	212	SLAB_PANIC, NULL);
3ef1355d BT	213
	214	/* Create workqueue for cleanup */
	215	netns_wq = create_singlethread_workqueue("netns");
	216	if (!netns_wq)
	217	panic("Could not create netns workq");
d57a9212	218	#endif
3ef1355d	219
486a87f1 DL	220	ng = net_alloc_generic();
	221	if (!ng)
	222	panic("Could not allocate generic netns");
	223
	224	rcu_assign_pointer(init_net.gen, ng);
	225
5f256bec EB	226	mutex_lock(&net_mutex);
	227	err = setup_net(&init_net);
	228
f4618d39	229	rtnl_lock();
5f256bec	230	list_add_tail(&init_net.list, &net_namespace_list);
f4618d39	231	rtnl_unlock();
5f256bec EB	232
	233	mutex_unlock(&net_mutex);
	234	if (err)
	235	panic("Could not setup the initial network namespace");
	236
	237	return 0;
	238	}
	239
	240	pure_initcall(net_ns_init);
	241
ed160e83	242	#ifdef CONFIG_NET_NS
5f256bec EB	243	static int register_pernet_operations(struct list_head *list,
	244	struct pernet_operations *ops)
	245	{
	246	struct net net, undo_net;
	247	int error;
	248
5f256bec	249	list_add_tail(&ops->list, list);
1dba323b PE	250	if (ops->init) {
1dba323b PE	251	for_each_net(net) {
5f256bec EB	252	error = ops->init(net);
	253	if (error)
	254	goto out_undo;
	255	}
	256	}
1dba323b	257	return 0;
5f256bec EB	258
	259	out_undo:
	260	/* If I have an error cleanup all namespaces I initialized */
	261	list_del(&ops->list);
1dba323b PE	262	if (ops->exit) {
	263	for_each_net(undo_net) {
	264	if (undo_net == net)
	265	goto undone;
5f256bec	266	ops->exit(undo_net);
1dba323b	267	}
5f256bec EB	268	}
5f256bec EB	269	undone:
1dba323b	270	return error;
5f256bec EB	271	}
	272
	273	static void unregister_pernet_operations(struct pernet_operations *ops)
	274	{
	275	struct net *net;
	276
	277	list_del(&ops->list);
1dba323b PE	278	if (ops->exit)
1dba323b PE	279	for_each_net(net)
5f256bec EB	280	ops->exit(net);
	281	}
	282
ed160e83 DL	283	#else
	284
	285	static int register_pernet_operations(struct list_head *list,
	286	struct pernet_operations *ops)
	287	{
	288	if (ops->init == NULL)
	289	return 0;
	290	return ops->init(&init_net);
	291	}
	292
	293	static void unregister_pernet_operations(struct pernet_operations *ops)
	294	{
	295	if (ops->exit)
	296	ops->exit(&init_net);
	297	}
	298	#endif
	299
c93cf61f PE	300	static DEFINE_IDA(net_generic_ids);
c93cf61f PE	301
5f256bec EB	302	/**
	303	* register_pernet_subsys - register a network namespace subsystem
	304	* @ops: pernet operations structure for the subsystem
	305	*
	306	* Register a subsystem which has init and exit functions
	307	* that are called when network namespaces are created and
	308	* destroyed respectively.
	309	*
	310	* When registered all network namespace init functions are
	311	* called for every existing network namespace. Allowing kernel
	312	* modules to have a race free view of the set of network namespaces.
	313	*
	314	* When a new network namespace is created all of the init
	315	* methods are called in the order in which they were registered.
	316	*
	317	* When a network namespace is destroyed all of the exit methods
	318	* are called in the reverse of the order with which they were
	319	* registered.
	320	*/
	321	int register_pernet_subsys(struct pernet_operations *ops)
	322	{
	323	int error;
	324	mutex_lock(&net_mutex);
	325	error = register_pernet_operations(first_device, ops);
	326	mutex_unlock(&net_mutex);
	327	return error;
	328	}
	329	EXPORT_SYMBOL_GPL(register_pernet_subsys);
	330
	331	/**
	332	* unregister_pernet_subsys - unregister a network namespace subsystem
	333	* @ops: pernet operations structure to manipulate
	334	*
	335	* Remove the pernet operations structure from the list to be
53379e57	336	* used when network namespaces are created or destroyed. In
5f256bec EB	337	* addition run the exit method for all existing network
	338	* namespaces.
	339	*/
	340	void unregister_pernet_subsys(struct pernet_operations *module)
	341	{
	342	mutex_lock(&net_mutex);
	343	unregister_pernet_operations(module);
	344	mutex_unlock(&net_mutex);
	345	}
	346	EXPORT_SYMBOL_GPL(unregister_pernet_subsys);
	347
485ac57b AD	348	int register_pernet_gen_subsys(int id, struct pernet_operations ops)
	349	{
	350	int rv;
	351
	352	mutex_lock(&net_mutex);
	353	again:
	354	rv = ida_get_new_above(&net_generic_ids, 1, id);
	355	if (rv < 0) {
	356	if (rv == -EAGAIN) {
	357	ida_pre_get(&net_generic_ids, GFP_KERNEL);
	358	goto again;
	359	}
	360	goto out;
	361	}
	362	rv = register_pernet_operations(first_device, ops);
	363	if (rv < 0)
	364	ida_remove(&net_generic_ids, *id);
485ac57b	365	out:
357f5b0b	366	mutex_unlock(&net_mutex);
485ac57b AD	367	return rv;
	368	}
	369	EXPORT_SYMBOL_GPL(register_pernet_gen_subsys);
	370
	371	void unregister_pernet_gen_subsys(int id, struct pernet_operations *ops)
	372	{
	373	mutex_lock(&net_mutex);
	374	unregister_pernet_operations(ops);
	375	ida_remove(&net_generic_ids, id);
	376	mutex_unlock(&net_mutex);
	377	}
	378	EXPORT_SYMBOL_GPL(unregister_pernet_gen_subsys);
	379
5f256bec EB	380	/**
	381	* register_pernet_device - register a network namespace device
	382	* @ops: pernet operations structure for the subsystem
	383	*
	384	* Register a device which has init and exit functions
	385	* that are called when network namespaces are created and
	386	* destroyed respectively.
	387	*
	388	* When registered all network namespace init functions are
	389	* called for every existing network namespace. Allowing kernel
	390	* modules to have a race free view of the set of network namespaces.
	391	*
	392	* When a new network namespace is created all of the init
	393	* methods are called in the order in which they were registered.
	394	*
	395	* When a network namespace is destroyed all of the exit methods
	396	* are called in the reverse of the order with which they were
	397	* registered.
	398	*/
	399	int register_pernet_device(struct pernet_operations *ops)
	400	{
	401	int error;
	402	mutex_lock(&net_mutex);
	403	error = register_pernet_operations(&pernet_list, ops);
	404	if (!error && (first_device == &pernet_list))
	405	first_device = &ops->list;
	406	mutex_unlock(&net_mutex);
	407	return error;
	408	}
	409	EXPORT_SYMBOL_GPL(register_pernet_device);
	410
c93cf61f PE	411	int register_pernet_gen_device(int id, struct pernet_operations ops)
	412	{
	413	int error;
	414	mutex_lock(&net_mutex);
	415	again:
	416	error = ida_get_new_above(&net_generic_ids, 1, id);
	417	if (error) {
	418	if (error == -EAGAIN) {
	419	ida_pre_get(&net_generic_ids, GFP_KERNEL);
	420	goto again;
	421	}
	422	goto out;
	423	}
	424	error = register_pernet_operations(&pernet_list, ops);
	425	if (error)
	426	ida_remove(&net_generic_ids, *id);
	427	else if (first_device == &pernet_list)
	428	first_device = &ops->list;
	429	out:
	430	mutex_unlock(&net_mutex);
	431	return error;
	432	}
	433	EXPORT_SYMBOL_GPL(register_pernet_gen_device);
	434
5f256bec EB	435	/**
	436	* unregister_pernet_device - unregister a network namespace netdevice
	437	* @ops: pernet operations structure to manipulate
	438	*
	439	* Remove the pernet operations structure from the list to be
53379e57	440	* used when network namespaces are created or destroyed. In
5f256bec EB	441	* addition run the exit method for all existing network
	442	* namespaces.
	443	*/
	444	void unregister_pernet_device(struct pernet_operations *ops)
	445	{
	446	mutex_lock(&net_mutex);
	447	if (&ops->list == first_device)
	448	first_device = first_device->next;
	449	unregister_pernet_operations(ops);
	450	mutex_unlock(&net_mutex);
	451	}
	452	EXPORT_SYMBOL_GPL(unregister_pernet_device);
c93cf61f PE	453
	454	void unregister_pernet_gen_device(int id, struct pernet_operations *ops)
	455	{
	456	mutex_lock(&net_mutex);
	457	if (&ops->list == first_device)
	458	first_device = first_device->next;
	459	unregister_pernet_operations(ops);
	460	ida_remove(&net_generic_ids, id);
	461	mutex_unlock(&net_mutex);
	462	}
	463	EXPORT_SYMBOL_GPL(unregister_pernet_gen_device);
dec827d1 PE	464
	465	static void net_generic_release(struct rcu_head *rcu)
	466	{
	467	struct net_generic *ng;
	468
	469	ng = container_of(rcu, struct net_generic, rcu);
	470	kfree(ng);
	471	}
	472
	473	int net_assign_generic(struct net net, int id, void data)
	474	{
	475	struct net_generic ng, old_ng;
	476
	477	BUG_ON(!mutex_is_locked(&net_mutex));
	478	BUG_ON(id == 0);
	479
	480	ng = old_ng = net->gen;
	481	if (old_ng->len >= id)
	482	goto assign;
	483
	484	ng = kzalloc(sizeof(struct net_generic) +
	485	id * sizeof(void *), GFP_KERNEL);
	486	if (ng == NULL)
	487	return -ENOMEM;
	488
	489	/*
	490	* Some synchronisation notes:
	491	*
	492	* The net_generic explores the net->gen array inside rcu
	493	* read section. Besides once set the net->gen->ptr[x]
	494	* pointer never changes (see rules in netns/generic.h).
	495	*
	496	* That said, we simply duplicate this array and schedule
	497	* the old copy for kfree after a grace period.
	498	*/
	499
	500	ng->len = id;
dec827d1 PE	501	memcpy(&ng->ptr, &old_ng->ptr, old_ng->len);
	502
	503	rcu_assign_pointer(net->gen, ng);
	504	call_rcu(&old_ng->rcu, net_generic_release);
	505	assign:
	506	ng->ptr[id - 1] = data;
	507	return 0;
	508	}
	509	EXPORT_SYMBOL_GPL(net_assign_generic);