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 */
batadv_hash_delete(struct batadv_hashtable * hash,batadv_hashdata_free_cb free_cb,void * arg)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 */
batadv_hash_add(struct batadv_hashtable * hash,batadv_hashdata_compare_cb compare,batadv_hashdata_choose_cb choose,const void * data,struct hlist_node * data_node)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 */
batadv_hash_remove(struct batadv_hashtable * hash,batadv_hashdata_compare_cb compare,batadv_hashdata_choose_cb choose,void * data)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