164 lines
4.4 KiB
C
164 lines
4.4 KiB
C
/*
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* Copyright (C) 2006-2011 B.A.T.M.A.N. contributors:
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*
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* Simon Wunderlich, Marek Lindner
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of version 2 of the GNU General Public
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* License as published by the Free Software Foundation.
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*
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* This program is distributed in the hope that it will be useful, but
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* WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
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* 02110-1301, USA
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*
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*/
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#ifndef _NET_BATMAN_ADV_HASH_H_
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#define _NET_BATMAN_ADV_HASH_H_
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#include <linux/list.h>
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/* callback to a compare function. should
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* compare 2 element datas for their keys,
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* return 0 if same and not 0 if not
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* same */
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typedef int (*hashdata_compare_cb)(const struct hlist_node *, const void *);
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/* the hashfunction, should return an index
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* based on the key in the data of the first
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* argument and the size the second */
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typedef uint32_t (*hashdata_choose_cb)(const void *, uint32_t);
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typedef void (*hashdata_free_cb)(struct hlist_node *, void *);
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struct hashtable_t {
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struct hlist_head *table; /* the hashtable itself with the buckets */
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spinlock_t *list_locks; /* spinlock for each hash list entry */
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uint32_t size; /* size of hashtable */
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};
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/* allocates and clears the hash */
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struct hashtable_t *hash_new(uint32_t size);
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/* free only the hashtable and the hash itself. */
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void hash_destroy(struct hashtable_t *hash);
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/* remove the hash structure. if hashdata_free_cb != NULL, this function will be
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* called to remove the elements inside of the hash. if you don't remove the
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* elements, memory might be leaked. */
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static inline void hash_delete(struct hashtable_t *hash,
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hashdata_free_cb free_cb, void *arg)
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{
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struct hlist_head *head;
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struct hlist_node *node, *node_tmp;
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spinlock_t *list_lock; /* spinlock to protect write access */
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uint32_t i;
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for (i = 0; i < hash->size; i++) {
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head = &hash->table[i];
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list_lock = &hash->list_locks[i];
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spin_lock_bh(list_lock);
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hlist_for_each_safe(node, node_tmp, head) {
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hlist_del_rcu(node);
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if (free_cb)
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free_cb(node, arg);
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}
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spin_unlock_bh(list_lock);
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}
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hash_destroy(hash);
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}
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/**
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* hash_add - adds data to the hashtable
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* @hash: storage hash table
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* @compare: callback to determine if 2 hash elements are identical
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* @choose: callback calculating the hash index
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* @data: data passed to the aforementioned callbacks as argument
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* @data_node: to be added element
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*
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* Returns 0 on success, 1 if the element already is in the hash
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* and -1 on error.
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*/
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static inline int hash_add(struct hashtable_t *hash,
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hashdata_compare_cb compare,
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hashdata_choose_cb choose,
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const void *data, struct hlist_node *data_node)
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{
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uint32_t index;
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int ret = -1;
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struct hlist_head *head;
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struct hlist_node *node;
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spinlock_t *list_lock; /* spinlock to protect write access */
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if (!hash)
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goto out;
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index = choose(data, hash->size);
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head = &hash->table[index];
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list_lock = &hash->list_locks[index];
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rcu_read_lock();
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__hlist_for_each_rcu(node, head) {
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if (!compare(node, data))
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continue;
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ret = 1;
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goto err_unlock;
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}
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rcu_read_unlock();
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/* no duplicate found in list, add new element */
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spin_lock_bh(list_lock);
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hlist_add_head_rcu(data_node, head);
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spin_unlock_bh(list_lock);
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ret = 0;
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goto out;
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err_unlock:
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rcu_read_unlock();
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out:
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return ret;
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}
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/* removes data from hash, if found. returns pointer do data on success, so you
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* can remove the used structure yourself, or NULL on error . data could be the
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* structure you use with just the key filled, we just need the key for
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* comparing. */
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static inline void *hash_remove(struct hashtable_t *hash,
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hashdata_compare_cb compare,
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hashdata_choose_cb choose, void *data)
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{
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uint32_t index;
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struct hlist_node *node;
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struct hlist_head *head;
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void *data_save = NULL;
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index = choose(data, hash->size);
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head = &hash->table[index];
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spin_lock_bh(&hash->list_locks[index]);
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hlist_for_each(node, head) {
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if (!compare(node, data))
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continue;
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data_save = node;
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hlist_del_rcu(node);
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break;
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}
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spin_unlock_bh(&hash->list_locks[index]);
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return data_save;
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}
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#endif /* _NET_BATMAN_ADV_HASH_H_ */
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