linux/net/batman-adv/hash.h

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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)(void *, 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)(void *, int);
typedef void (*hashdata_free_cb)(void *, void *);
struct element_t {
void *data; /* pointer to the data */
struct hlist_node hlist; /* bucket list pointer */
struct rcu_head rcu;
};
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);
void bucket_free_rcu(struct rcu_head *rcu);
/* 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 *walk, *safe;
struct element_t *bucket;
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_entry_safe(bucket, walk, safe, head, hlist) {
if (free_cb)
free_cb(bucket->data, arg);
hlist_del_rcu(walk);
call_rcu(&bucket->rcu, bucket_free_rcu);
}
spin_unlock_bh(list_lock);
}
hash_destroy(hash);
}
/* adds data to the hashtable. returns 0 on success, -1 on error */
static inline int hash_add(struct hashtable_t *hash,
hashdata_compare_cb compare,
hashdata_choose_cb choose, void *data)
{
int index;
struct hlist_head *head;
struct hlist_node *walk, *safe;
struct element_t *bucket;
spinlock_t *list_lock; /* spinlock to protect write access */
if (!hash)
goto err;
index = choose(data, hash->size);
head = &hash->table[index];
list_lock = &hash->list_locks[index];
rcu_read_lock();
hlist_for_each_entry_safe(bucket, walk, safe, head, hlist) {
if (compare(bucket->data, data))
goto err_unlock;
}
rcu_read_unlock();
/* no duplicate found in list, add new element */
bucket = kmalloc(sizeof(struct element_t), GFP_ATOMIC);
if (!bucket)
goto err;
bucket->data = data;
spin_lock_bh(list_lock);
hlist_add_head_rcu(&bucket->hlist, head);
spin_unlock_bh(list_lock);
return 0;
err_unlock:
rcu_read_unlock();
err:
return -1;
}
/* 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 *walk;
struct element_t *bucket;
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_entry(bucket, walk, head, hlist) {
if (compare(bucket->data, data)) {
data_save = bucket->data;
hlist_del_rcu(walk);
call_rcu(&bucket->rcu, bucket_free_rcu);
break;
}
}
spin_unlock_bh(&hash->list_locks[index]);
return data_save;
}
/**
* finds data, based on the key in keydata. returns the found data on success,
* or NULL on error
*
* caller must lock with rcu_read_lock() / rcu_read_unlock()
**/
static inline void *hash_find(struct hashtable_t *hash,
hashdata_compare_cb compare,
hashdata_choose_cb choose, void *keydata)
{
int index;
struct hlist_head *head;
struct hlist_node *walk;
struct element_t *bucket;
void *bucket_data = NULL;
if (!hash)
return NULL;
index = choose(keydata , hash->size);
head = &hash->table[index];
hlist_for_each_entry(bucket, walk, head, hlist) {
if (compare(bucket->data, keydata)) {
bucket_data = bucket->data;
break;
}
}
return bucket_data;
}
#endif /* _NET_BATMAN_ADV_HASH_H_ */