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/* Copyright (C) 2006-2012 B.A.T.M.A.N. contributors:
*
* Simon Wunderlich, Marek Lindner
*
* 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.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
* 02110-1301, USA
*/
#ifndef _NET_BATMAN_ADV_HASH_H_
#define _NET_BATMAN_ADV_HASH_H_
#include <linux/list.h>
/* callback to a compare function. should compare 2 element datas for their
* keys, return 0 if same and not 0 if not same
*/
typedef int (*batadv_hashdata_compare_cb)(const struct hlist_node *,
const void *);
/* the hashfunction, should return an index
* based on the key in the data of the first
* argument and the size the second
*/
typedef uint32_t (*batadv_hashdata_choose_cb)(const void *, uint32_t);
typedef void (*batadv_hashdata_free_cb)(struct hlist_node *, void *);
struct batadv_hashtable {
struct hlist_head *table; /* the hashtable itself with the buckets */
spinlock_t *list_locks; /* spinlock for each hash list entry */
uint32_t size; /* size of hashtable */
};
/* allocates and clears the hash */
struct batadv_hashtable *batadv_hash_new(uint32_t size);
/* set class key for all locks */
void batadv_hash_set_lock_class(struct batadv_hashtable *hash,
struct lock_class_key *key);
/* free only the hashtable and the hash itself. */
void batadv_hash_destroy(struct batadv_hashtable *hash);
/* remove the hash structure. if hashdata_free_cb != NULL, this function will be
* called to remove the elements inside of the hash. if you don't remove the
* elements, memory might be leaked.
*/
static inline void batadv_hash_delete(struct batadv_hashtable *hash,
batadv_hashdata_free_cb free_cb,
void *arg)
{
struct hlist_head *head;
struct hlist_node *node, *node_tmp;
spinlock_t *list_lock; /* spinlock to protect write access */
uint32_t i;
for (i = 0; i < hash->size; i++) {
head = &hash->table[i];
list_lock = &hash->list_locks[i];
spin_lock_bh(list_lock);
hlist_for_each_safe(node, node_tmp, head) {
hlist_del_rcu(node);
if (free_cb)
free_cb(node, arg);
}
spin_unlock_bh(list_lock);
}
batadv_hash_destroy(hash);
}
/**
* batadv_hash_bytes - hash some bytes and add them to the previous hash
* @hash: previous hash value
* @data: data to be hashed
* @size: number of bytes to be hashed
*
* Returns the new hash value.
*/
static inline uint32_t batadv_hash_bytes(uint32_t hash, const void *data,
uint32_t size)
{
const unsigned char *key = data;
int i;
for (i = 0; i < size; i++) {
hash += key[i];
hash += (hash << 10);
hash ^= (hash >> 6);
}
return hash;
}
/**
* batadv_hash_add - adds data to the hashtable
* @hash: storage hash table
* @compare: callback to determine if 2 hash elements are identical
* @choose: callback calculating the hash index
* @data: data passed to the aforementioned callbacks as argument
* @data_node: to be added element
*
* Returns 0 on success, 1 if the element already is in the hash
* and -1 on error.
*/
static inline int batadv_hash_add(struct batadv_hashtable *hash,
batadv_hashdata_compare_cb compare,
batadv_hashdata_choose_cb choose,
const void *data,
struct hlist_node *data_node)
{
uint32_t index;
int ret = -1;
struct hlist_head *head;
struct hlist_node *node;
spinlock_t *list_lock; /* spinlock to protect write access */
if (!hash)
goto out;
index = choose(data, hash->size);
head = &hash->table[index];
list_lock = &hash->list_locks[index];
spin_lock_bh(list_lock);
hlist_for_each(node, head) {
if (!compare(node, data))
continue;
ret = 1;
goto unlock;
}
/* no duplicate found in list, add new element */
hlist_add_head_rcu(data_node, head);
ret = 0;
unlock:
spin_unlock_bh(list_lock);
out:
return ret;
}
/* removes data from hash, if found. returns pointer do data on success, so you
* can remove the used structure yourself, or NULL on error . data could be the
* structure you use with just the key filled, we just need the key for
* comparing.
*/
static inline void *batadv_hash_remove(struct batadv_hashtable *hash,
batadv_hashdata_compare_cb compare,
batadv_hashdata_choose_cb choose,
void *data)
{
uint32_t index;
struct hlist_node *node;
struct hlist_head *head;
void *data_save = NULL;
index = choose(data, hash->size);
head = &hash->table[index];
spin_lock_bh(&hash->list_locks[index]);
hlist_for_each(node, head) {
if (!compare(node, data))
continue;
data_save = node;
hlist_del_rcu(node);
break;
}
spin_unlock_bh(&hash->list_locks[index]);
return data_save;
}
#endif /* _NET_BATMAN_ADV_HASH_H_ */
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