[linux.git] / kernel / bpf / hashtab.c

/* Copyright (c) 2011-2014 PLUMgrid, http://plumgrid.com
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of version 2 of the GNU General Public
 * License as published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
 * General Public License for more details.
 */
#include <linux/bpf.h>
#include <linux/jhash.h>
#include <linux/filter.h>
#include <linux/vmalloc.h>

struct bucket {
	struct hlist_head head;
	raw_spinlock_t lock;
};

struct bpf_htab {
	struct bpf_map map;
	struct bucket *buckets;
	atomic_t count;	/* number of elements in this hashtable */
	u32 n_buckets;	/* number of hash buckets */
	u32 elem_size;	/* size of each element in bytes */
};

/* each htab element is struct htab_elem + key + value */
struct htab_elem {
	struct hlist_node hash_node;
	struct rcu_head rcu;
	u32 hash;
	char key[0] __aligned(8);
};

/* Called from syscall */
static struct bpf_map *htab_map_alloc(union bpf_attr *attr)
{
	struct bpf_htab *htab;
	int err, i;

	htab = kzalloc(sizeof(*htab), GFP_USER);
	if (!htab)
		return ERR_PTR(-ENOMEM);

	/* mandatory map attributes */
	htab->map.key_size = attr->key_size;
	htab->map.value_size = attr->value_size;
	htab->map.max_entries = attr->max_entries;

	/* check sanity of attributes.
	 * value_size == 0 may be allowed in the future to use map as a set
	 */
	err = -EINVAL;
	if (htab->map.max_entries == 0 || htab->map.key_size == 0 ||
	    htab->map.value_size == 0)
		goto free_htab;

	/* hash table size must be power of 2 */
	htab->n_buckets = roundup_pow_of_two(htab->map.max_entries);

	err = -E2BIG;
	if (htab->map.key_size > MAX_BPF_STACK)
		/* eBPF programs initialize keys on stack, so they cannot be
		 * larger than max stack size
		 */
		goto free_htab;

	if (htab->map.value_size >= (1 << (KMALLOC_SHIFT_MAX - 1)) -
	    MAX_BPF_STACK - sizeof(struct htab_elem))
		/* if value_size is bigger, the user space won't be able to
		 * access the elements via bpf syscall. This check also makes
		 * sure that the elem_size doesn't overflow and it's
		 * kmalloc-able later in htab_map_update_elem()
		 */
		goto free_htab;

	htab->elem_size = sizeof(struct htab_elem) +
			  round_up(htab->map.key_size, 8) +
			  htab->map.value_size;

	/* prevent zero size kmalloc and check for u32 overflow */
	if (htab->n_buckets == 0 ||
	    htab->n_buckets > U32_MAX / sizeof(struct bucket))
		goto free_htab;

	if ((u64) htab->n_buckets * sizeof(struct bucket) +
	    (u64) htab->elem_size * htab->map.max_entries >=
	    U32_MAX - PAGE_SIZE)
		/* make sure page count doesn't overflow */
		goto free_htab;

	htab->map.pages = round_up(htab->n_buckets * sizeof(struct bucket) +
				   htab->elem_size * htab->map.max_entries,
				   PAGE_SIZE) >> PAGE_SHIFT;

	err = -ENOMEM;
	htab->buckets = kmalloc_array(htab->n_buckets, sizeof(struct bucket),
				      GFP_USER | __GFP_NOWARN);

	if (!htab->buckets) {
		htab->buckets = vmalloc(htab->n_buckets * sizeof(struct bucket));
		if (!htab->buckets)
			goto free_htab;
	}

	for (i = 0; i < htab->n_buckets; i++) {
		INIT_HLIST_HEAD(&htab->buckets[i].head);
		raw_spin_lock_init(&htab->buckets[i].lock);
	}

	atomic_set(&htab->count, 0);

	return &htab->map;

free_htab:
	kfree(htab);
	return ERR_PTR(err);
}

static inline u32 htab_map_hash(const void *key, u32 key_len)
{
	return jhash(key, key_len, 0);
}

static inline struct bucket *__select_bucket(struct bpf_htab *htab, u32 hash)
{
	return &htab->buckets[hash & (htab->n_buckets - 1)];
}

static inline struct hlist_head *select_bucket(struct bpf_htab *htab, u32 hash)
{
	return &__select_bucket(htab, hash)->head;
}

static struct htab_elem *lookup_elem_raw(struct hlist_head *head, u32 hash,
					 void *key, u32 key_size)
{
	struct htab_elem *l;

	hlist_for_each_entry_rcu(l, head, hash_node)
		if (l->hash == hash && !memcmp(&l->key, key, key_size))
			return l;

	return NULL;
}

/* Called from syscall or from eBPF program */
static void *htab_map_lookup_elem(struct bpf_map *map, void *key)
{
	struct bpf_htab *htab = container_of(map, struct bpf_htab, map);
	struct hlist_head *head;
	struct htab_elem *l;
	u32 hash, key_size;

	/* Must be called with rcu_read_lock. */
	WARN_ON_ONCE(!rcu_read_lock_held());

	key_size = map->key_size;

	hash = htab_map_hash(key, key_size);

	head = select_bucket(htab, hash);

	l = lookup_elem_raw(head, hash, key, key_size);

	if (l)
		return l->key + round_up(map->key_size, 8);

	return NULL;
}

/* Called from syscall */
static int htab_map_get_next_key(struct bpf_map *map, void *key, void *next_key)
{
	struct bpf_htab *htab = container_of(map, struct bpf_htab, map);
	struct hlist_head *head;
	struct htab_elem *l, *next_l;
	u32 hash, key_size;
	int i;

	WARN_ON_ONCE(!rcu_read_lock_held());

	key_size = map->key_size;

	hash = htab_map_hash(key, key_size);

	head = select_bucket(htab, hash);

	/* lookup the key */
	l = lookup_elem_raw(head, hash, key, key_size);

	if (!l) {
		i = 0;
		goto find_first_elem;
	}

	/* key was found, get next key in the same bucket */
	next_l = hlist_entry_safe(rcu_dereference_raw(hlist_next_rcu(&l->hash_node)),
				  struct htab_elem, hash_node);

	if (next_l) {
		/* if next elem in this hash list is non-zero, just return it */
		memcpy(next_key, next_l->key, key_size);
		return 0;
	}

	/* no more elements in this hash list, go to the next bucket */
	i = hash & (htab->n_buckets - 1);
	i++;

find_first_elem:
	/* iterate over buckets */
	for (; i < htab->n_buckets; i++) {
		head = select_bucket(htab, i);

		/* pick first element in the bucket */
		next_l = hlist_entry_safe(rcu_dereference_raw(hlist_first_rcu(head)),
					  struct htab_elem, hash_node);
		if (next_l) {
			/* if it's not empty, just return it */
			memcpy(next_key, next_l->key, key_size);
			return 0;
		}
	}

	/* itereated over all buckets and all elements */
	return -ENOENT;
}

/* Called from syscall or from eBPF program */
static int htab_map_update_elem(struct bpf_map *map, void *key, void *value,
				u64 map_flags)
{
	struct bpf_htab *htab = container_of(map, struct bpf_htab, map);
	struct htab_elem *l_new, *l_old;
	struct hlist_head *head;
	struct bucket *b;
	unsigned long flags;
	u32 key_size;
	int ret;

	if (map_flags > BPF_EXIST)
		/* unknown flags */
		return -EINVAL;

	WARN_ON_ONCE(!rcu_read_lock_held());

	/* allocate new element outside of lock */
	l_new = kmalloc(htab->elem_size, GFP_ATOMIC | __GFP_NOWARN);
	if (!l_new)
		return -ENOMEM;

	key_size = map->key_size;

	memcpy(l_new->key, key, key_size);
	memcpy(l_new->key + round_up(key_size, 8), value, map->value_size);

	l_new->hash = htab_map_hash(l_new->key, key_size);
	b = __select_bucket(htab, l_new->hash);
	head = &b->head;

	/* bpf_map_update_elem() can be called in_irq() */
	raw_spin_lock_irqsave(&b->lock, flags);

	l_old = lookup_elem_raw(head, l_new->hash, key, key_size);

	if (!l_old && unlikely(atomic_read(&htab->count) >= map->max_entries)) {
		/* if elem with this 'key' doesn't exist and we've reached
		 * max_entries limit, fail insertion of new elem
		 */
		ret = -E2BIG;
		goto err;
	}

	if (l_old && map_flags == BPF_NOEXIST) {
		/* elem already exists */
		ret = -EEXIST;
		goto err;
	}

	if (!l_old && map_flags == BPF_EXIST) {
		/* elem doesn't exist, cannot update it */
		ret = -ENOENT;
		goto err;
	}

	/* add new element to the head of the list, so that concurrent
	 * search will find it before old elem
	 */
	hlist_add_head_rcu(&l_new->hash_node, head);
	if (l_old) {
		hlist_del_rcu(&l_old->hash_node);
		kfree_rcu(l_old, rcu);
	} else {
		atomic_inc(&htab->count);
	}
	raw_spin_unlock_irqrestore(&b->lock, flags);

	return 0;
err:
	raw_spin_unlock_irqrestore(&b->lock, flags);
	kfree(l_new);
	return ret;
}

/* Called from syscall or from eBPF program */
static int htab_map_delete_elem(struct bpf_map *map, void *key)
{
	struct bpf_htab *htab = container_of(map, struct bpf_htab, map);
	struct hlist_head *head;
	struct bucket *b;
	struct htab_elem *l;
	unsigned long flags;
	u32 hash, key_size;
	int ret = -ENOENT;

	WARN_ON_ONCE(!rcu_read_lock_held());

	key_size = map->key_size;

	hash = htab_map_hash(key, key_size);
	b = __select_bucket(htab, hash);
	head = &b->head;

	raw_spin_lock_irqsave(&b->lock, flags);

	l = lookup_elem_raw(head, hash, key, key_size);

	if (l) {
		hlist_del_rcu(&l->hash_node);
		atomic_dec(&htab->count);
		kfree_rcu(l, rcu);
		ret = 0;
	}

	raw_spin_unlock_irqrestore(&b->lock, flags);
	return ret;
}

static void delete_all_elements(struct bpf_htab *htab)
{
	int i;

	for (i = 0; i < htab->n_buckets; i++) {
		struct hlist_head *head = select_bucket(htab, i);
		struct hlist_node *n;
		struct htab_elem *l;

		hlist_for_each_entry_safe(l, n, head, hash_node) {
			hlist_del_rcu(&l->hash_node);
			atomic_dec(&htab->count);
			kfree(l);
		}
	}
}

/* Called when map->refcnt goes to zero, either from workqueue or from syscall */
static void htab_map_free(struct bpf_map *map)
{
	struct bpf_htab *htab = container_of(map, struct bpf_htab, map);

	/* at this point bpf_prog->aux->refcnt == 0 and this map->refcnt == 0,
	 * so the programs (can be more than one that used this map) were
	 * disconnected from events. Wait for outstanding critical sections in
	 * these programs to complete
	 */
	synchronize_rcu();

	/* some of kfree_rcu() callbacks for elements of this map may not have
	 * executed. It's ok. Proceed to free residual elements and map itself
	 */
	delete_all_elements(htab);
	kvfree(htab->buckets);
	kfree(htab);
}

static const struct bpf_map_ops htab_ops = {
	.map_alloc = htab_map_alloc,
	.map_free = htab_map_free,
	.map_get_next_key = htab_map_get_next_key,
	.map_lookup_elem = htab_map_lookup_elem,
	.map_update_elem = htab_map_update_elem,
	.map_delete_elem = htab_map_delete_elem,
};

static struct bpf_map_type_list htab_type __read_mostly = {
	.ops = &htab_ops,
	.type = BPF_MAP_TYPE_HASH,
};

static int __init register_htab_map(void)
{
	bpf_register_map_type(&htab_type);
	return 0;
}
late_initcall(register_htab_map);
Commit	Line	Data
0f8e4bd8 AS	1	/* Copyright (c) 2011-2014 PLUMgrid, http://plumgrid.com
	2	*
	3	* This program is free software; you can redistribute it and/or
	4	* modify it under the terms of version 2 of the GNU General Public
	5	* License as published by the Free Software Foundation.
	6	*
	7	* This program is distributed in the hope that it will be useful, but
	8	* WITHOUT ANY WARRANTY; without even the implied warranty of
	9	* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
	10	* General Public License for more details.
	11	*/
	12	#include <linux/bpf.h>
	13	#include <linux/jhash.h>
	14	#include <linux/filter.h>
	15	#include <linux/vmalloc.h>
	16
688ecfe6	17	struct bucket {
	18	struct hlist_head head;
	19	raw_spinlock_t lock;
	20	};
	21
0f8e4bd8 AS	22	struct bpf_htab {
0f8e4bd8 AS	23	struct bpf_map map;
688ecfe6	24	struct bucket *buckets;
6591f1e6	25	atomic_t count; /* number of elements in this hashtable */
0f8e4bd8 AS	26	u32 n_buckets; /* number of hash buckets */
	27	u32 elem_size; /* size of each element in bytes */
	28	};
	29
	30	/* each htab element is struct htab_elem + key + value */
	31	struct htab_elem {
	32	struct hlist_node hash_node;
	33	struct rcu_head rcu;
	34	u32 hash;
	35	char key[0] __aligned(8);
	36	};
	37
	38	/* Called from syscall */
	39	static struct bpf_map htab_map_alloc(union bpf_attr attr)
	40	{
	41	struct bpf_htab *htab;
	42	int err, i;
	43
	44	htab = kzalloc(sizeof(*htab), GFP_USER);
	45	if (!htab)
	46	return ERR_PTR(-ENOMEM);
	47
	48	/* mandatory map attributes */
	49	htab->map.key_size = attr->key_size;
	50	htab->map.value_size = attr->value_size;
	51	htab->map.max_entries = attr->max_entries;
	52
	53	/* check sanity of attributes.
	54	* value_size == 0 may be allowed in the future to use map as a set
	55	*/
	56	err = -EINVAL;
	57	if (htab->map.max_entries == 0 \|\| htab->map.key_size == 0 \|\|
	58	htab->map.value_size == 0)
	59	goto free_htab;
	60
	61	/* hash table size must be power of 2 */
	62	htab->n_buckets = roundup_pow_of_two(htab->map.max_entries);
	63
	64	err = -E2BIG;
	65	if (htab->map.key_size > MAX_BPF_STACK)
	66	/* eBPF programs initialize keys on stack, so they cannot be
	67	* larger than max stack size
	68	*/
	69	goto free_htab;
	70
01b3f521 AS	71	if (htab->map.value_size >= (1 << (KMALLOC_SHIFT_MAX - 1)) -
	72	MAX_BPF_STACK - sizeof(struct htab_elem))
	73	/* if value_size is bigger, the user space won't be able to
	74	* access the elements via bpf syscall. This check also makes
	75	* sure that the elem_size doesn't overflow and it's
	76	* kmalloc-able later in htab_map_update_elem()
	77	*/
	78	goto free_htab;
	79
	80	htab->elem_size = sizeof(struct htab_elem) +
	81	round_up(htab->map.key_size, 8) +
	82	htab->map.value_size;
	83
daaf427c AS	84	/* prevent zero size kmalloc and check for u32 overflow */
daaf427c AS	85	if (htab->n_buckets == 0 \|\|
688ecfe6	86	htab->n_buckets > U32_MAX / sizeof(struct bucket))
daaf427c AS	87	goto free_htab;
daaf427c AS	88
688ecfe6	89	if ((u64) htab->n_buckets * sizeof(struct bucket) +
01b3f521 AS	90	(u64) htab->elem_size * htab->map.max_entries >=
	91	U32_MAX - PAGE_SIZE)
	92	/* make sure page count doesn't overflow */
	93	goto free_htab;
	94
688ecfe6	95	htab->map.pages = round_up(htab->n_buckets * sizeof(struct bucket) +
01b3f521 AS	96	htab->elem_size * htab->map.max_entries,
	97	PAGE_SIZE) >> PAGE_SHIFT;
	98
	99	err = -ENOMEM;
688ecfe6	100	htab->buckets = kmalloc_array(htab->n_buckets, sizeof(struct bucket),
0f8e4bd8 AS	101	GFP_USER \| __GFP_NOWARN);
	102
	103	if (!htab->buckets) {
688ecfe6	104	htab->buckets = vmalloc(htab->n_buckets * sizeof(struct bucket));
0f8e4bd8 AS	105	if (!htab->buckets)
	106	goto free_htab;
	107	}
	108
688ecfe6	109	for (i = 0; i < htab->n_buckets; i++) {
	110	INIT_HLIST_HEAD(&htab->buckets[i].head);
	111	raw_spin_lock_init(&htab->buckets[i].lock);
	112	}
0f8e4bd8	113
6591f1e6	114	atomic_set(&htab->count, 0);
0f8e4bd8	115
0f8e4bd8 AS	116	return &htab->map;
	117
	118	free_htab:
	119	kfree(htab);
	120	return ERR_PTR(err);
	121	}
	122
	123	static inline u32 htab_map_hash(const void *key, u32 key_len)
	124	{
	125	return jhash(key, key_len, 0);
	126	}
	127
688ecfe6	128	static inline struct bucket __select_bucket(struct bpf_htab htab, u32 hash)
0f8e4bd8 AS	129	{
	130	return &htab->buckets[hash & (htab->n_buckets - 1)];
	131	}
	132
688ecfe6	133	static inline struct hlist_head select_bucket(struct bpf_htab htab, u32 hash)
	134	{
	135	return &__select_bucket(htab, hash)->head;
	136	}
	137
0f8e4bd8 AS	138	static struct htab_elem lookup_elem_raw(struct hlist_head head, u32 hash,
	139	void *key, u32 key_size)
	140	{
	141	struct htab_elem *l;
	142
	143	hlist_for_each_entry_rcu(l, head, hash_node)
	144	if (l->hash == hash && !memcmp(&l->key, key, key_size))
	145	return l;
	146
	147	return NULL;
	148	}
	149
	150	/* Called from syscall or from eBPF program */
	151	static void htab_map_lookup_elem(struct bpf_map map, void *key)
	152	{
	153	struct bpf_htab *htab = container_of(map, struct bpf_htab, map);
	154	struct hlist_head *head;
	155	struct htab_elem *l;
	156	u32 hash, key_size;
	157
	158	/* Must be called with rcu_read_lock. */
	159	WARN_ON_ONCE(!rcu_read_lock_held());
	160
	161	key_size = map->key_size;
	162
	163	hash = htab_map_hash(key, key_size);
	164
	165	head = select_bucket(htab, hash);
	166
	167	l = lookup_elem_raw(head, hash, key, key_size);
	168
	169	if (l)
	170	return l->key + round_up(map->key_size, 8);
	171
	172	return NULL;
	173	}
	174
	175	/* Called from syscall */
	176	static int htab_map_get_next_key(struct bpf_map map, void key, void *next_key)
	177	{
	178	struct bpf_htab *htab = container_of(map, struct bpf_htab, map);
	179	struct hlist_head *head;
	180	struct htab_elem l, next_l;
	181	u32 hash, key_size;
	182	int i;
	183
	184	WARN_ON_ONCE(!rcu_read_lock_held());
	185
	186	key_size = map->key_size;
	187
	188	hash = htab_map_hash(key, key_size);
	189
	190	head = select_bucket(htab, hash);
	191
	192	/* lookup the key */
	193	l = lookup_elem_raw(head, hash, key, key_size);
	194
	195	if (!l) {
	196	i = 0;
	197	goto find_first_elem;
	198	}
	199
	200	/* key was found, get next key in the same bucket */
	201	next_l = hlist_entry_safe(rcu_dereference_raw(hlist_next_rcu(&l->hash_node)),
202	struct htab_elem, hash_node);
203
204	if (next_l) {
205	/* if next elem in this hash list is non-zero, just return it */
206	memcpy(next_key, next_l->key, key_size);
207	return 0;
208	}
209
210	/* no more elements in this hash list, go to the next bucket */
211	i = hash & (htab->n_buckets - 1);
212	i++;
213
214	find_first_elem:
215	/* iterate over buckets */
216	for (; i < htab->n_buckets; i++) {
217	head = select_bucket(htab, i);
218
219	/* pick first element in the bucket */
220	next_l = hlist_entry_safe(rcu_dereference_raw(hlist_first_rcu(head)),
221	struct htab_elem, hash_node);
222	if (next_l) {
223	/* if it's not empty, just return it */
224	memcpy(next_key, next_l->key, key_size);
225	return 0;
226	}
227	}
228
229	/* itereated over all buckets and all elements */
230	return -ENOENT;
231	}
232
233	/* Called from syscall or from eBPF program */
234	static int htab_map_update_elem(struct bpf_map map, void key, void *value,
235	u64 map_flags)
236	{
237	struct bpf_htab *htab = container_of(map, struct bpf_htab, map);
238	struct htab_elem l_new, l_old;
239	struct hlist_head *head;
688ecfe6	240	struct bucket *b;
0f8e4bd8 AS	241	unsigned long flags;
	242	u32 key_size;
	243	int ret;
	244
	245	if (map_flags > BPF_EXIST)
	246	/* unknown flags */
	247	return -EINVAL;
	248
	249	WARN_ON_ONCE(!rcu_read_lock_held());
	250
	251	/* allocate new element outside of lock */
01b3f521	252	l_new = kmalloc(htab->elem_size, GFP_ATOMIC \| __GFP_NOWARN);
0f8e4bd8 AS	253	if (!l_new)
	254	return -ENOMEM;
	255
	256	key_size = map->key_size;
	257
	258	memcpy(l_new->key, key, key_size);
	259	memcpy(l_new->key + round_up(key_size, 8), value, map->value_size);
	260
	261	l_new->hash = htab_map_hash(l_new->key, key_size);
688ecfe6	262	b = __select_bucket(htab, l_new->hash);
688ecfe6	263	head = &b->head;
0f8e4bd8 AS	264
0f8e4bd8 AS	265	/* bpf_map_update_elem() can be called in_irq() */
688ecfe6	266	raw_spin_lock_irqsave(&b->lock, flags);
0f8e4bd8	267
0f8e4bd8 AS	268	l_old = lookup_elem_raw(head, l_new->hash, key, key_size);
0f8e4bd8 AS	269
6591f1e6	270	if (!l_old && unlikely(atomic_read(&htab->count) >= map->max_entries)) {
0f8e4bd8 AS	271	/* if elem with this 'key' doesn't exist and we've reached
	272	* max_entries limit, fail insertion of new elem
	273	*/
	274	ret = -E2BIG;
	275	goto err;
	276	}
	277
	278	if (l_old && map_flags == BPF_NOEXIST) {
	279	/* elem already exists */
	280	ret = -EEXIST;
	281	goto err;
	282	}
	283
	284	if (!l_old && map_flags == BPF_EXIST) {
	285	/* elem doesn't exist, cannot update it */
	286	ret = -ENOENT;
	287	goto err;
	288	}
	289
	290	/* add new element to the head of the list, so that concurrent
	291	* search will find it before old elem
	292	*/
	293	hlist_add_head_rcu(&l_new->hash_node, head);
	294	if (l_old) {
	295	hlist_del_rcu(&l_old->hash_node);
	296	kfree_rcu(l_old, rcu);
	297	} else {
6591f1e6	298	atomic_inc(&htab->count);
0f8e4bd8	299	}
688ecfe6	300	raw_spin_unlock_irqrestore(&b->lock, flags);
0f8e4bd8 AS	301
	302	return 0;
	303	err:
688ecfe6	304	raw_spin_unlock_irqrestore(&b->lock, flags);
0f8e4bd8 AS	305	kfree(l_new);
	306	return ret;
	307	}
	308
	309	/* Called from syscall or from eBPF program */
	310	static int htab_map_delete_elem(struct bpf_map map, void key)
	311	{
	312	struct bpf_htab *htab = container_of(map, struct bpf_htab, map);
	313	struct hlist_head *head;
688ecfe6	314	struct bucket *b;
0f8e4bd8 AS	315	struct htab_elem *l;
	316	unsigned long flags;
	317	u32 hash, key_size;
	318	int ret = -ENOENT;
	319
	320	WARN_ON_ONCE(!rcu_read_lock_held());
	321
	322	key_size = map->key_size;
	323
	324	hash = htab_map_hash(key, key_size);
688ecfe6	325	b = __select_bucket(htab, hash);
688ecfe6	326	head = &b->head;
0f8e4bd8	327
688ecfe6	328	raw_spin_lock_irqsave(&b->lock, flags);
0f8e4bd8	329
0f8e4bd8 AS	330	l = lookup_elem_raw(head, hash, key, key_size);
	331
	332	if (l) {
	333	hlist_del_rcu(&l->hash_node);
6591f1e6	334	atomic_dec(&htab->count);
0f8e4bd8 AS	335	kfree_rcu(l, rcu);
	336	ret = 0;
	337	}
	338
688ecfe6	339	raw_spin_unlock_irqrestore(&b->lock, flags);
0f8e4bd8 AS	340	return ret;
	341	}
	342
	343	static void delete_all_elements(struct bpf_htab *htab)
	344	{
	345	int i;
	346
	347	for (i = 0; i < htab->n_buckets; i++) {
	348	struct hlist_head *head = select_bucket(htab, i);
	349	struct hlist_node *n;
	350	struct htab_elem *l;
	351
	352	hlist_for_each_entry_safe(l, n, head, hash_node) {
	353	hlist_del_rcu(&l->hash_node);
6591f1e6	354	atomic_dec(&htab->count);
0f8e4bd8 AS	355	kfree(l);
	356	}
	357	}
	358	}
	359
	360	/* Called when map->refcnt goes to zero, either from workqueue or from syscall */
	361	static void htab_map_free(struct bpf_map *map)
	362	{
	363	struct bpf_htab *htab = container_of(map, struct bpf_htab, map);
	364
	365	/* at this point bpf_prog->aux->refcnt == 0 and this map->refcnt == 0,
	366	* so the programs (can be more than one that used this map) were
	367	* disconnected from events. Wait for outstanding critical sections in
	368	* these programs to complete
	369	*/
	370	synchronize_rcu();
	371
	372	/* some of kfree_rcu() callbacks for elements of this map may not have
	373	* executed. It's ok. Proceed to free residual elements and map itself
	374	*/
	375	delete_all_elements(htab);
	376	kvfree(htab->buckets);
	377	kfree(htab);
	378	}
	379
a2c83fff	380	static const struct bpf_map_ops htab_ops = {
0f8e4bd8 AS	381	.map_alloc = htab_map_alloc,
	382	.map_free = htab_map_free,
	383	.map_get_next_key = htab_map_get_next_key,
	384	.map_lookup_elem = htab_map_lookup_elem,
	385	.map_update_elem = htab_map_update_elem,
	386	.map_delete_elem = htab_map_delete_elem,
	387	};
	388
a2c83fff	389	static struct bpf_map_type_list htab_type __read_mostly = {
0f8e4bd8 AS	390	.ops = &htab_ops,
	391	.type = BPF_MAP_TYPE_HASH,
	392	};
	393
	394	static int __init register_htab_map(void)
	395	{
a2c83fff	396	bpf_register_map_type(&htab_type);
0f8e4bd8 AS	397	return 0;
	398	}
	399	late_initcall(register_htab_map);