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/*
* Copyright (C) 2006-2011 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 (*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 int (*hashdata_choose_cb)(const void *, int);
typedef void (*hashdata_free_cb)(struct hlist_node *, void *);
struct hashtable_t {
struct hlist_head *table; /* the hashtable itself with the buckets */
spinlock_t *list_locks; /* spinlock for each hash list entry */
int size; /* size of hashtable */
};
/* allocates and clears the hash */
struct hashtable_t *hash_new(int size);
/* free only the hashtable and the hash itself. */
void hash_destroy(struct hashtable_t *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 hash_delete(struct hashtable_t *hash,
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 */
int 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);
}
hash_destroy(hash);
}
/**
* 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 hash_add(struct hashtable_t *hash,
hashdata_compare_cb compare,
hashdata_choose_cb choose,
const void *data, struct hlist_node *data_node)
{
int index, 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];
rcu_read_lock();
__hlist_for_each_rcu(node, head) {
if (!compare(node, data))
continue;
ret = 1;
goto err_unlock;
}
rcu_read_unlock();
/* no duplicate found in list, add new element */
spin_lock_bh(list_lock);
hlist_add_head_rcu(data_node, head);
spin_unlock_bh(list_lock);
ret = 0;
goto out;
err_unlock:
rcu_read_unlock();
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 *hash_remove(struct hashtable_t *hash,
hashdata_compare_cb compare,
hashdata_choose_cb choose, void *data)
{
size_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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