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

   1/* Copyright (C) 2006-2013 B.A.T.M.A.N. contributors:
   2 *
   3 * Simon Wunderlich, Marek Lindner
   4 *
   5 * This program is free software; you can redistribute it and/or
   6 * modify it under the terms of version 2 of the GNU General Public
   7 * License as published by the Free Software Foundation.
   8 *
   9 * This program is distributed in the hope that it will be useful, but
  10 * WITHOUT ANY WARRANTY; without even the implied warranty of
  11 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  12 * General Public License for more details.
  13 *
  14 * You should have received a copy of the GNU General Public License
  15 * along with this program; if not, write to the Free Software
  16 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
  17 * 02110-1301, USA
  18 */
  19
  20#ifndef _NET_BATMAN_ADV_HASH_H_
  21#define _NET_BATMAN_ADV_HASH_H_
  22
  23#include <linux/list.h>
  24
  25/* callback to a compare function.  should compare 2 element datas for their
  26 * keys, return 0 if same and not 0 if not same
  27 */
  28typedef int (*batadv_hashdata_compare_cb)(const struct hlist_node *,
  29                                          const void *);
  30
  31/* the hashfunction, should return an index
  32 * based on the key in the data of the first
  33 * argument and the size the second
  34 */
  35typedef uint32_t (*batadv_hashdata_choose_cb)(const void *, uint32_t);
  36typedef void (*batadv_hashdata_free_cb)(struct hlist_node *, void *);
  37
  38struct batadv_hashtable {
  39        struct hlist_head *table;   /* the hashtable itself with the buckets */
  40        spinlock_t *list_locks;     /* spinlock for each hash list entry */
  41        uint32_t size;              /* size of hashtable */
  42};
  43
  44/* allocates and clears the hash */
  45struct batadv_hashtable *batadv_hash_new(uint32_t size);
  46
  47/* set class key for all locks */
  48void batadv_hash_set_lock_class(struct batadv_hashtable *hash,
  49                                struct lock_class_key *key);
  50
  51/* free only the hashtable and the hash itself. */
  52void batadv_hash_destroy(struct batadv_hashtable *hash);
  53
  54/* remove the hash structure. if hashdata_free_cb != NULL, this function will be
  55 * called to remove the elements inside of the hash.  if you don't remove the
  56 * elements, memory might be leaked.
  57 */
  58static inline void batadv_hash_delete(struct batadv_hashtable *hash,
  59                                      batadv_hashdata_free_cb free_cb,
  60                                      void *arg)
  61{
  62        struct hlist_head *head;
  63        struct hlist_node *node, *node_tmp;
  64        spinlock_t *list_lock; /* spinlock to protect write access */
  65        uint32_t i;
  66
  67        for (i = 0; i < hash->size; i++) {
  68                head = &hash->table[i];
  69                list_lock = &hash->list_locks[i];
  70
  71                spin_lock_bh(list_lock);
  72                hlist_for_each_safe(node, node_tmp, head) {
  73                        hlist_del_rcu(node);
  74
  75                        if (free_cb)
  76                                free_cb(node, arg);
  77                }
  78                spin_unlock_bh(list_lock);
  79        }
  80
  81        batadv_hash_destroy(hash);
  82}
  83
  84/**
  85 *      batadv_hash_bytes - hash some bytes and add them to the previous hash
  86 *      @hash: previous hash value
  87 *      @data: data to be hashed
  88 *      @size: number of bytes to be hashed
  89 *
  90 *      Returns the new hash value.
  91 */
  92static inline uint32_t batadv_hash_bytes(uint32_t hash, const void *data,
  93                                         uint32_t size)
  94{
  95        const unsigned char *key = data;
  96        int i;
  97
  98        for (i = 0; i < size; i++) {
  99                hash += key[i];
 100                hash += (hash << 10);
 101                hash ^= (hash >> 6);
 102        }
 103        return hash;
 104}
 105
 106/**
 107 *      batadv_hash_add - adds data to the hashtable
 108 *      @hash: storage hash table
 109 *      @compare: callback to determine if 2 hash elements are identical
 110 *      @choose: callback calculating the hash index
 111 *      @data: data passed to the aforementioned callbacks as argument
 112 *      @data_node: to be added element
 113 *
 114 *      Returns 0 on success, 1 if the element already is in the hash
 115 *      and -1 on error.
 116 */
 117static inline int batadv_hash_add(struct batadv_hashtable *hash,
 118                                  batadv_hashdata_compare_cb compare,
 119                                  batadv_hashdata_choose_cb choose,
 120                                  const void *data,
 121                                  struct hlist_node *data_node)
 122{
 123        uint32_t index;
 124        int ret = -1;
 125        struct hlist_head *head;
 126        struct hlist_node *node;
 127        spinlock_t *list_lock; /* spinlock to protect write access */
 128
 129        if (!hash)
 130                goto out;
 131
 132        index = choose(data, hash->size);
 133        head = &hash->table[index];
 134        list_lock = &hash->list_locks[index];
 135
 136        spin_lock_bh(list_lock);
 137
 138        hlist_for_each(node, head) {
 139                if (!compare(node, data))
 140                        continue;
 141
 142                ret = 1;
 143                goto unlock;
 144        }
 145
 146        /* no duplicate found in list, add new element */
 147        hlist_add_head_rcu(data_node, head);
 148
 149        ret = 0;
 150
 151unlock:
 152        spin_unlock_bh(list_lock);
 153out:
 154        return ret;
 155}
 156
 157/* removes data from hash, if found. returns pointer do data on success, so you
 158 * can remove the used structure yourself, or NULL on error .  data could be the
 159 * structure you use with just the key filled, we just need the key for
 160 * comparing.
 161 */
 162static inline void *batadv_hash_remove(struct batadv_hashtable *hash,
 163                                       batadv_hashdata_compare_cb compare,
 164                                       batadv_hashdata_choose_cb choose,
 165                                       void *data)
 166{
 167        uint32_t index;
 168        struct hlist_node *node;
 169        struct hlist_head *head;
 170        void *data_save = NULL;
 171
 172        index = choose(data, hash->size);
 173        head = &hash->table[index];
 174
 175        spin_lock_bh(&hash->list_locks[index]);
 176        hlist_for_each(node, head) {
 177                if (!compare(node, data))
 178                        continue;
 179
 180                data_save = node;
 181                hlist_del_rcu(node);
 182                break;
 183        }
 184        spin_unlock_bh(&hash->list_locks[index]);
 185
 186        return data_save;
 187}
 188
 189#endif /* _NET_BATMAN_ADV_HASH_H_ */
 190