net/batman-adv/hash.h

   1 /* Copyright (C) 2006-2016  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
  34  *
  35  * Return: true if same and false if not same
  36  */
  37 typedef bool (*batadv_hashdata_compare_cb)(const struct hlist_node *,
  38                                            const void *);
  39
  40 /* the hashfunction
  41  *
  42  * Return: an index based on the key in the data of the first argument and the
  43  * size the second
  44  */
  45 typedef u32 (*batadv_hashdata_choose_cb)(const void *, u32);
  46 typedef void (*batadv_hashdata_free_cb)(struct hlist_node *, void *);
  47
  48 struct batadv_hashtable {
  49         struct hlist_head *table;   /* the hashtable itself with the buckets */
  50         spinlock_t *list_locks;     /* spinlock for each hash list entry */
  51         u32 size;                   /* size of hashtable */
  52 };
  53
  54 /* allocates and clears the hash */
  55 struct batadv_hashtable *batadv_hash_new(u32 size);
  56
  57 /* set class key for all locks */
  58 void batadv_hash_set_lock_class(struct batadv_hashtable *hash,
  59                                 struct lock_class_key *key);
  60
  61 /* free only the hashtable and the hash itself. */
  62 void batadv_hash_destroy(struct batadv_hashtable *hash);
  63
  64 /* remove the hash structure. if hashdata_free_cb != NULL, this function will be
  65  * called to remove the elements inside of the hash.  if you don't remove the
  66  * elements, memory might be leaked.
  67  */
  68 static inline void batadv_hash_delete(struct batadv_hashtable *hash,
  69                                       batadv_hashdata_free_cb free_cb,
  70                                       void *arg)
  71 {
  72         struct hlist_head *head;
  73         struct hlist_node *node, *node_tmp;
  74         spinlock_t *list_lock; /* spinlock to protect write access */
  75         u32 i;
  76
  77         for (i = 0; i < hash->size; i++) {
  78                 head = &hash->table[i];
  79                 list_lock = &hash->list_locks[i];
  80
  81                 spin_lock_bh(list_lock);
  82                 hlist_for_each_safe(node, node_tmp, head) {
  83                         hlist_del_rcu(node);
  84
  85                         if (free_cb)
  86                                 free_cb(node, arg);
  87                 }
  88                 spin_unlock_bh(list_lock);
  89         }
  90
  91         batadv_hash_destroy(hash);
  92 }
  93
  94 /**
  95  *      batadv_hash_add - adds data to the hashtable
  96  *      @hash: storage hash table
  97  *      @compare: callback to determine if 2 hash elements are identical
  98  *      @choose: callback calculating the hash index
  99  *      @data: data passed to the aforementioned callbacks as argument
 100  *      @data_node: to be added element
 101  *
 102  *      Return: 0 on success, 1 if the element already is in the hash
 103  *      and -1 on error.
 104  */
 105 static inline int batadv_hash_add(struct batadv_hashtable *hash,
 106                                   batadv_hashdata_compare_cb compare,
 107                                   batadv_hashdata_choose_cb choose,
 108                                   const void *data,
 109                                   struct hlist_node *data_node)
 110 {
 111         u32 index;
 112         int ret = -1;
 113         struct hlist_head *head;
 114         struct hlist_node *node;
 115         spinlock_t *list_lock; /* spinlock to protect write access */
 116
 117         if (!hash)
 118                 goto out;
 119
 120         index = choose(data, hash->size);
 121         head = &hash->table[index];
 122         list_lock = &hash->list_locks[index];
 123
 124         spin_lock_bh(list_lock);
 125
 126         hlist_for_each(node, head) {
 127                 if (!compare(node, data))
 128                         continue;
 129
 130                 ret = 1;
 131                 goto unlock;
 132         }
 133
 134         /* no duplicate found in list, add new element */
 135         hlist_add_head_rcu(data_node, head);
 136
 137         ret = 0;
 138
 139 unlock:
 140         spin_unlock_bh(list_lock);
 141 out:
 142         return ret;
 143 }
 144
 145 /* removes data from hash, if found. data could be the structure you use with
 146  * just the key filled, we just need the key for comparing.
 147  *
 148  * Return: returns pointer do data on success, so you can remove the used
 149  * structure yourself, or NULL on error
 150  */
 151 static inline void *batadv_hash_remove(struct batadv_hashtable *hash,
 152                                        batadv_hashdata_compare_cb compare,
 153                                        batadv_hashdata_choose_cb choose,
 154                                        void *data)
 155 {
 156         u32 index;
 157         struct hlist_node *node;
 158         struct hlist_head *head;
 159         void *data_save = NULL;
 160
 161         index = choose(data, hash->size);
 162         head = &hash->table[index];
 163
 164         spin_lock_bh(&hash->list_locks[index]);
 165         hlist_for_each(node, head) {
 166                 if (!compare(node, data))
 167                         continue;
 168
 169                 data_save = node;
 170                 hlist_del_rcu(node);
 171                 break;
 172         }
 173         spin_unlock_bh(&hash->list_locks[index]);
 174
 175         return data_save;
 176 }
 177
 178 #endif /* _NET_BATMAN_ADV_HASH_H_ */