LXR linux/net/batman-adv/hash.h

   1/* SPDX-License-Identifier: GPL-2.0 */
   2/* Copyright (C) 2006-2017  B.A.T.M.A.N. contributors:
   3 *
   4 * Simon Wunderlich, Marek Lindner
   5 *
   6 * This program is free software; you can redistribute it and/or
   7 * modify it under the terms of version 2 of the GNU General Public
   8 * License as published by the Free Software Foundation.
   9 *
  10 * This program is distributed in the hope that it will be useful, but
  11 * WITHOUT ANY WARRANTY; without even the implied warranty of
  12 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  13 * General Public License for more details.
  14 *
  15 * You should have received a copy of the GNU General Public License
  16 * along with this program; if not, see <http://www.gnu.org/licenses/>.
  17 */
  18
  19#ifndef _NET_BATMAN_ADV_HASH_H_
  20#define _NET_BATMAN_ADV_HASH_H_
  21
  22#include "main.h"
  23
  24#include <linux/compiler.h>
  25#include <linux/list.h>
  26#include <linux/rculist.h>
  27#include <linux/spinlock.h>
  28#include <linux/stddef.h>
  29#include <linux/types.h>
  30
  31struct lock_class_key;
  32
  33/* callback to a compare function.  should compare 2 element datas for their
  34 * keys
  35 *
  36 * Return: true if same and false if not same
  37 */
  38typedef bool (*batadv_hashdata_compare_cb)(const struct hlist_node *,
  39                                           const void *);
  40
  41/* the hashfunction
  42 *
  43 * Return: an index based on the key in the data of the first argument and the
  44 * size the second
  45 */
  46typedef u32 (*batadv_hashdata_choose_cb)(const void *, u32);
  47typedef void (*batadv_hashdata_free_cb)(struct hlist_node *, void *);
  48
  49/**
  50 * struct batadv_hashtable - Wrapper of simple hlist based hashtable
  51 */
  52struct batadv_hashtable {
  53        /** @table: the hashtable itself with the buckets */
  54        struct hlist_head *table;
  55
  56        /** @list_locks: spinlock for each hash list entry */
  57        spinlock_t *list_locks;
  58
  59        /** @size: size of hashtable */
  60        u32 size;
  61};
  62
  63/* allocates and clears the hash */
  64struct batadv_hashtable *batadv_hash_new(u32 size);
  65
  66/* set class key for all locks */
  67void batadv_hash_set_lock_class(struct batadv_hashtable *hash,
  68                                struct lock_class_key *key);
  69
  70/* free only the hashtable and the hash itself. */
  71void batadv_hash_destroy(struct batadv_hashtable *hash);
  72
  73/**
  74 *      batadv_hash_add() - adds data to the hashtable
  75 *      @hash: storage hash table
  76 *      @compare: callback to determine if 2 hash elements are identical
  77 *      @choose: callback calculating the hash index
  78 *      @data: data passed to the aforementioned callbacks as argument
  79 *      @data_node: to be added element
  80 *
  81 *      Return: 0 on success, 1 if the element already is in the hash
  82 *      and -1 on error.
  83 */
  84static inline int batadv_hash_add(struct batadv_hashtable *hash,
  85                                  batadv_hashdata_compare_cb compare,
  86                                  batadv_hashdata_choose_cb choose,
  87                                  const void *data,
  88                                  struct hlist_node *data_node)
  89{
  90        u32 index;
  91        int ret = -1;
  92        struct hlist_head *head;
  93        struct hlist_node *node;
  94        spinlock_t *list_lock; /* spinlock to protect write access */
  95
  96        if (!hash)
  97                goto out;
  98
  99        index = choose(data, hash->size);
 100        head = &hash->table[index];
 101        list_lock = &hash->list_locks[index];
 102
 103        spin_lock_bh(list_lock);
 104
 105        hlist_for_each(node, head) {
 106                if (!compare(node, data))
 107                        continue;
 108
 109                ret = 1;
 110                goto unlock;
 111        }
 112
 113        /* no duplicate found in list, add new element */
 114        hlist_add_head_rcu(data_node, head);
 115
 116        ret = 0;
 117
 118unlock:
 119        spin_unlock_bh(list_lock);
 120out:
 121        return ret;
 122}
 123
 124/**
 125 * batadv_hash_remove() - Removes data from hash, if found
 126 * @hash: hash table
 127 * @compare: callback to determine if 2 hash elements are identical
 128 * @choose: callback calculating the hash index
 129 * @data: data passed to the aforementioned callbacks as argument
 130 *
 131 * ata could be the structure you use with  just the key filled, we just need
 132 * the key for comparing.
 133 *
 134 * Return: returns pointer do data on success, so you can remove the used
 135 * structure yourself, or NULL on error
 136 */
 137static inline void *batadv_hash_remove(struct batadv_hashtable *hash,
 138                                       batadv_hashdata_compare_cb compare,
 139                                       batadv_hashdata_choose_cb choose,
 140                                       void *data)
 141{
 142        u32 index;
 143        struct hlist_node *node;
 144        struct hlist_head *head;
 145        void *data_save = NULL;
 146
 147        index = choose(data, hash->size);
 148        head = &hash->table[index];
 149
 150        spin_lock_bh(&hash->list_locks[index]);
 151        hlist_for_each(node, head) {
 152                if (!compare(node, data))
 153                        continue;
 154
 155                data_save = node;
 156                hlist_del_rcu(node);
 157                break;
 158        }
 159        spin_unlock_bh(&hash->list_locks[index]);
 160
 161        return data_save;
 162}
 163
 164#endif /* _NET_BATMAN_ADV_HASH_H_ */
 165