linux/net/batman-adv/hash.h
Antonio Quartulli c90681b850 batman-adv: fixed hash functions type to uint32_t instead of int
There are two reasons for this fix:
- the result of choose_orig() and vis_choose() is an index and therefore it can't
  be negative. Hence it is correct to make the return type unsigned too.

- sizeof(int) may not be the same on ALL the architectures. Since we plan to use
  choose_orig() as DHT hash function, we need to guarantee that, given the same
  argument, the result is the same. Then it is correct to explicitly express
  the size of the return type (and the second argument). Since the expected
  length is currently 4, uint32_t is the most convenient choice.

Signed-off-by: Antonio Quartulli <ordex@autistici.org>
Signed-off-by: Sven Eckelmann <sven@narfation.org>
2011-11-20 13:08:33 +01:00

164 lines
4.4 KiB
C

/*
* 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 uint32_t (*hashdata_choose_cb)(const void *, uint32_t);
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 */
uint32_t size; /* size of hashtable */
};
/* allocates and clears the hash */
struct hashtable_t *hash_new(uint32_t 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 */
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);
}
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)
{
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];
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)
{
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_ */