171 lines
4.5 KiB
C
171 lines
4.5 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
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/* Copyright (C) 2006-2019 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, see <http://www.gnu.org/licenses/>.
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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 "main.h"
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#include <linux/atomic.h>
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#include <linux/compiler.h>
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#include <linux/list.h>
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#include <linux/rculist.h>
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#include <linux/spinlock.h>
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#include <linux/stddef.h>
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#include <linux/types.h>
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struct lock_class_key;
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/* callback to a compare function. should compare 2 element datas for their
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* keys
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*
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* Return: true if same and false if not same
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*/
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typedef bool (*batadv_hashdata_compare_cb)(const struct hlist_node *,
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const void *);
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/* the hashfunction
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*
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* Return: an index based on the key in the data of the first argument and the
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* size the second
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*/
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typedef u32 (*batadv_hashdata_choose_cb)(const void *, u32);
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typedef void (*batadv_hashdata_free_cb)(struct hlist_node *, void *);
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/**
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* struct batadv_hashtable - Wrapper of simple hlist based hashtable
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*/
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struct batadv_hashtable {
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/** @table: the hashtable itself with the buckets */
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struct hlist_head *table;
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/** @list_locks: spinlock for each hash list entry */
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spinlock_t *list_locks;
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/** @size: size of hashtable */
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u32 size;
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/** @generation: current (generation) sequence number */
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atomic_t generation;
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};
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/* allocates and clears the hash */
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struct batadv_hashtable *batadv_hash_new(u32 size);
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/* set class key for all locks */
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void batadv_hash_set_lock_class(struct batadv_hashtable *hash,
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struct lock_class_key *key);
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/* free only the hashtable and the hash itself. */
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void batadv_hash_destroy(struct batadv_hashtable *hash);
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/**
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* batadv_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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* Return: 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 batadv_hash_add(struct batadv_hashtable *hash,
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batadv_hashdata_compare_cb compare,
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batadv_hashdata_choose_cb choose,
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const void *data,
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struct hlist_node *data_node)
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{
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u32 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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spin_lock_bh(list_lock);
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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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ret = 1;
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goto unlock;
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}
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/* no duplicate found in list, add new element */
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hlist_add_head_rcu(data_node, head);
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atomic_inc(&hash->generation);
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ret = 0;
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unlock:
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spin_unlock_bh(list_lock);
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out:
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return ret;
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}
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/**
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* batadv_hash_remove() - Removes data from hash, if found
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* @hash: 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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*
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* ata could be the structure you use with just the key filled, we just need
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* the key for comparing.
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*
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* Return: returns pointer do data on success, so you can remove the used
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* structure yourself, or NULL on error
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*/
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static inline void *batadv_hash_remove(struct batadv_hashtable *hash,
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batadv_hashdata_compare_cb compare,
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batadv_hashdata_choose_cb choose,
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void *data)
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{
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u32 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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atomic_inc(&hash->generation);
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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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