net/batman-adv/hash.h

   1 /* Copyright (C) 2006-2012 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  */
  28 typedef int (*hashdata_compare_cb)(const struct hlist_node *, const void *);
  29
  30 /* the hashfunction, should return an index
  31  * based on the key in the data of the first
  32  * argument and the size the second
  33  */
  34 typedef uint32_t (*hashdata_choose_cb)(const void *, uint32_t);
  35 typedef void (*hashdata_free_cb)(struct hlist_node *, void *);
  36
  37 struct hashtable_t {
  38         struct hlist_head *table;   /* the hashtable itself with the buckets */
  39         spinlock_t *list_locks;     /* spinlock for each hash list entry */
  40         uint32_t size;              /* size of hashtable */
  41 };
  42
  43 /* allocates and clears the hash */
  44 struct hashtable_t *batadv_hash_new(uint32_t size);
  45
  46 /* set class key for all locks */
  47 void batadv_hash_set_lock_class(struct hashtable_t *hash,
  48                                 struct lock_class_key *key);
  49
  50 /* free only the hashtable and the hash itself. */
  51 void batadv_hash_destroy(struct hashtable_t *hash);
  52
  53 /* remove the hash structure. if hashdata_free_cb != NULL, this function will be
  54  * called to remove the elements inside of the hash.  if you don't remove the
  55  * elements, memory might be leaked.
  56  */
  57 static inline void hash_delete(struct hashtable_t *hash,
  58                                hashdata_free_cb free_cb, void *arg)
  59 {
  60         struct hlist_head *head;
  61         struct hlist_node *node, *node_tmp;
  62         spinlock_t *list_lock; /* spinlock to protect write access */
  63         uint32_t i;
  64
  65         for (i = 0; i < hash->size; i++) {
  66                 head = &hash->table[i];
  67                 list_lock = &hash->list_locks[i];
  68
  69                 spin_lock_bh(list_lock);
  70                 hlist_for_each_safe(node, node_tmp, head) {
  71                         hlist_del_rcu(node);
  72
  73                         if (free_cb)
  74                                 free_cb(node, arg);
  75                 }
  76                 spin_unlock_bh(list_lock);
  77         }
  78
  79         batadv_hash_destroy(hash);
  80 }
  81
  82 /*      hash_add - adds data to the hashtable
  83  *      @hash: storage hash table
  84  *      @compare: callback to determine if 2 hash elements are identical
  85  *      @choose: callback calculating the hash index
  86  *      @data: data passed to the aforementioned callbacks as argument
  87  *      @data_node: to be added element
  88  *
  89  *      Returns 0 on success, 1 if the element already is in the hash
  90  *      and -1 on error.
  91  */
  92 static inline int hash_add(struct hashtable_t *hash,
  93                            hashdata_compare_cb compare,
  94                            hashdata_choose_cb choose,
  95                            const void *data, struct hlist_node *data_node)
  96 {
  97         uint32_t index;
  98         int ret = -1;
  99         struct hlist_head *head;
 100         struct hlist_node *node;
 101         spinlock_t *list_lock; /* spinlock to protect write access */
 102
 103         if (!hash)
 104                 goto out;
 105
 106         index = choose(data, hash->size);
 107         head = &hash->table[index];
 108         list_lock = &hash->list_locks[index];
 109
 110         spin_lock_bh(list_lock);
 111
 112         hlist_for_each(node, head) {
 113                 if (!compare(node, data))
 114                         continue;
 115
 116                 ret = 1;
 117                 goto unlock;
 118         }
 119
 120         /* no duplicate found in list, add new element */
 121         hlist_add_head_rcu(data_node, head);
 122
 123         ret = 0;
 124
 125 unlock:
 126         spin_unlock_bh(list_lock);
 127 out:
 128         return ret;
 129 }
 130
 131 /* removes data from hash, if found. returns pointer do data on success, so you
 132  * can remove the used structure yourself, or NULL on error .  data could be the
 133  * structure you use with just the key filled, we just need the key for
 134  * comparing.
 135  */
 136 static inline void *hash_remove(struct hashtable_t *hash,
 137                                 hashdata_compare_cb compare,
 138                                 hashdata_choose_cb choose, void *data)
 139 {
 140         uint32_t index;
 141         struct hlist_node *node;
 142         struct hlist_head *head;
 143         void *data_save = NULL;
 144
 145         index = choose(data, hash->size);
 146         head = &hash->table[index];
 147
 148         spin_lock_bh(&hash->list_locks[index]);
 149         hlist_for_each(node, head) {
 150                 if (!compare(node, data))
 151                         continue;
 152
 153                 data_save = node;
 154                 hlist_del_rcu(node);
 155                 break;
 156         }
 157         spin_unlock_bh(&hash->list_locks[index]);
 158
 159         return data_save;
 160 }
 161
 162 #endif /* _NET_BATMAN_ADV_HASH_H_ */