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Linux/net/batman-adv/hash.h

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  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_ */
179 

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