net/batman-adv/hash.h

   1 /* Copyright (C) 2006-2015 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, see <http://www.gnu.org/licenses/>.
  16  */
  17
  18 #ifndef _NET_BATMAN_ADV_HASH_H_
  19 #define _NET_BATMAN_ADV_HASH_H_
  20
  21 #include "main.h"
  22
  23 #include <linux/compiler.h>
  24 #include <linux/list.h>
  25 #include <linux/rculist.h>
  26 #include <linux/spinlock.h>
  27 #include <linux/stddef.h>
  28 #include <linux/types.h>
  29
  30 struct lock_class_key;
  31
  32 /* callback to a compare function.  should compare 2 element datas for their
  33  * keys, return 0 if same and not 0 if not same
  34  */
  35 typedef int (*batadv_hashdata_compare_cb)(const struct hlist_node *,
  36                                           const void *);
  37
  38 /* the hashfunction, should return an index
  39  * based on the key in the data of the first
  40  * argument and the size the second
  41  */
  42 typedef u32 (*batadv_hashdata_choose_cb)(const void *, u32);
  43 typedef void (*batadv_hashdata_free_cb)(struct hlist_node *, void *);
  44
  45 struct batadv_hashtable {
  46         struct hlist_head *table;   /* the hashtable itself with the buckets */
  47         spinlock_t *list_locks;     /* spinlock for each hash list entry */
  48         u32 size;                   /* size of hashtable */
  49 };
  50
  51 /* allocates and clears the hash */
  52 struct batadv_hashtable *batadv_hash_new(u32 size);
  53
  54 /* set class key for all locks */
  55 void batadv_hash_set_lock_class(struct batadv_hashtable *hash,
  56                                 struct lock_class_key *key);
  57
  58 /* free only the hashtable and the hash itself. */
  59 void batadv_hash_destroy(struct batadv_hashtable *hash);
  60
  61 /* remove the hash structure. if hashdata_free_cb != NULL, this function will be
  62  * called to remove the elements inside of the hash.  if you don't remove the
  63  * elements, memory might be leaked.
  64  */
  65 static inline void batadv_hash_delete(struct batadv_hashtable *hash,
  66                                       batadv_hashdata_free_cb free_cb,
  67                                       void *arg)
  68 {
  69         struct hlist_head *head;
  70         struct hlist_node *node, *node_tmp;
  71         spinlock_t *list_lock; /* spinlock to protect write access */
  72         u32 i;
  73
  74         for (i = 0; i < hash->size; i++) {
  75                 head = &hash->table[i];
  76                 list_lock = &hash->list_locks[i];
  77
  78                 spin_lock_bh(list_lock);
  79                 hlist_for_each_safe(node, node_tmp, head) {
  80                         hlist_del_rcu(node);
  81
  82                         if (free_cb)
  83                                 free_cb(node, arg);
  84                 }
  85                 spin_unlock_bh(list_lock);
  86         }
  87
  88         batadv_hash_destroy(hash);
  89 }
  90
  91 /**
  92  *      batadv_hash_add - adds data to the hashtable
  93  *      @hash: storage hash table
  94  *      @compare: callback to determine if 2 hash elements are identical
  95  *      @choose: callback calculating the hash index
  96  *      @data: data passed to the aforementioned callbacks as argument
  97  *      @data_node: to be added element
  98  *
  99  *      Returns 0 on success, 1 if the element already is in the hash
 100  *      and -1 on error.
 101  */
 102 static inline int batadv_hash_add(struct batadv_hashtable *hash,
 103                                   batadv_hashdata_compare_cb compare,
 104                                   batadv_hashdata_choose_cb choose,
 105                                   const void *data,
 106                                   struct hlist_node *data_node)
 107 {
 108         u32 index;
 109         int ret = -1;
 110         struct hlist_head *head;
 111         struct hlist_node *node;
 112         spinlock_t *list_lock; /* spinlock to protect write access */
 113
 114         if (!hash)
 115                 goto out;
 116
 117         index = choose(data, hash->size);
 118         head = &hash->table[index];
 119         list_lock = &hash->list_locks[index];
 120
 121         spin_lock_bh(list_lock);
 122
 123         hlist_for_each(node, head) {
 124                 if (!compare(node, data))
 125                         continue;
 126
 127                 ret = 1;
 128                 goto unlock;
 129         }
 130
 131         /* no duplicate found in list, add new element */
 132         hlist_add_head_rcu(data_node, head);
 133
 134         ret = 0;
 135
 136 unlock:
 137         spin_unlock_bh(list_lock);
 138 out:
 139         return ret;
 140 }
 141
 142 /* removes data from hash, if found. returns pointer do data on success, so you
 143  * can remove the used structure yourself, or NULL on error .  data could be the
 144  * structure you use with just the key filled, we just need the key for
 145  * comparing.
 146  */
 147 static inline void *batadv_hash_remove(struct batadv_hashtable *hash,
 148                                        batadv_hashdata_compare_cb compare,
 149                                        batadv_hashdata_choose_cb choose,
 150                                        void *data)
 151 {
 152         u32 index;
 153         struct hlist_node *node;
 154         struct hlist_head *head;
 155         void *data_save = NULL;
 156
 157         index = choose(data, hash->size);
 158         head = &hash->table[index];
 159
 160         spin_lock_bh(&hash->list_locks[index]);
 161         hlist_for_each(node, head) {
 162                 if (!compare(node, data))
 163                         continue;
 164
 165                 data_save = node;
 166                 hlist_del_rcu(node);
 167                 break;
 168         }
 169         spin_unlock_bh(&hash->list_locks[index]);
 170
 171         return data_save;
 172 }
 173
 174 #endif /* _NET_BATMAN_ADV_HASH_H_ */