1 /* SPDX-License-Identifier: GPL-2.0 */
2 /* Copyright (C) 2006-2018 B.A.T.M.A.N. contributors:
3 *
4 * Simon Wunderlich, Marek Lindner
5 *
6 * This program is free software; you can redistribute it and/or
7 * modify it under the terms of version 2 of the GNU General Public
8 * License as published by the Free Software Foundation.
9 *
10 * This program is distributed in the hope that it will be useful, but
11 * WITHOUT ANY WARRANTY; without even the implied warranty of
12 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
13 * General Public License for more details.
14 *
15 * You should have received a copy of the GNU General Public License
16 * along with this program; if not, see <http://www.gnu.org/licenses/>.
17 */
18
19 #ifndef _NET_BATMAN_ADV_HASH_H_
20 #define _NET_BATMAN_ADV_HASH_H_
21
22 #include "main.h"
23
24 #include <linux/compiler.h>
25 #include <linux/list.h>
26 #include <linux/rculist.h>
27 #include <linux/spinlock.h>
28 #include <linux/stddef.h>
29 #include <linux/types.h>
30
31 struct lock_class_key;
32
33 /* callback to a compare function. should compare 2 element datas for their
34 * keys
35 *
36 * Return: true if same and false if not same
37 */
38 typedef bool (*batadv_hashdata_compare_cb)(const struct hlist_node *,
39 const void *);
40
41 /* the hashfunction
42 *
43 * Return: an index based on the key in the data of the first argument and the
44 * size the second
45 */
46 typedef u32 (*batadv_hashdata_choose_cb)(const void *, u32);
47 typedef void (*batadv_hashdata_free_cb)(struct hlist_node *, void *);
48
49 /**
50 * struct batadv_hashtable - Wrapper of simple hlist based hashtable
51 */
52 struct batadv_hashtable {
53 /** @table: the hashtable itself with the buckets */
54 struct hlist_head *table;
55
56 /** @list_locks: spinlock for each hash list entry */
57 spinlock_t *list_locks;
58
59 /** @size: size of hashtable */
60 u32 size;
61 };
62
63 /* allocates and clears the hash */
64 struct batadv_hashtable *batadv_hash_new(u32 size);
65
66 /* set class key for all locks */
67 void batadv_hash_set_lock_class(struct batadv_hashtable *hash,
68 struct lock_class_key *key);
69
70 /* free only the hashtable and the hash itself. */
71 void batadv_hash_destroy(struct batadv_hashtable *hash);
72
73 /**
74 * batadv_hash_add() - adds data to the hashtable
75 * @hash: storage hash table
76 * @compare: callback to determine if 2 hash elements are identical
77 * @choose: callback calculating the hash index
78 * @data: data passed to the aforementioned callbacks as argument
79 * @data_node: to be added element
80 *
81 * Return: 0 on success, 1 if the element already is in the hash
82 * and -1 on error.
83 */
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)84 static inline int batadv_hash_add(struct batadv_hashtable *hash,
85 batadv_hashdata_compare_cb compare,
86 batadv_hashdata_choose_cb choose,
87 const void *data,
88 struct hlist_node *data_node)
89 {
90 u32 index;
91 int ret = -1;
92 struct hlist_head *head;
93 struct hlist_node *node;
94 spinlock_t *list_lock; /* spinlock to protect write access */
95
96 if (!hash)
97 goto out;
98
99 index = choose(data, hash->size);
100 head = &hash->table[index];
101 list_lock = &hash->list_locks[index];
102
103 spin_lock_bh(list_lock);
104
105 hlist_for_each(node, head) {
106 if (!compare(node, data))
107 continue;
108
109 ret = 1;
110 goto unlock;
111 }
112
113 /* no duplicate found in list, add new element */
114 hlist_add_head_rcu(data_node, head);
115
116 ret = 0;
117
118 unlock:
119 spin_unlock_bh(list_lock);
120 out:
121 return ret;
122 }
123
124 /**
125 * batadv_hash_remove() - Removes data from hash, if found
126 * @hash: hash table
127 * @compare: callback to determine if 2 hash elements are identical
128 * @choose: callback calculating the hash index
129 * @data: data passed to the aforementioned callbacks as argument
130 *
131 * ata could be the structure you use with just the key filled, we just need
132 * the key for comparing.
133 *
134 * Return: returns pointer do data on success, so you can remove the used
135 * structure yourself, or NULL on error
136 */
batadv_hash_remove(struct batadv_hashtable * hash,batadv_hashdata_compare_cb compare,batadv_hashdata_choose_cb choose,void * data)137 static inline void *batadv_hash_remove(struct batadv_hashtable *hash,
138 batadv_hashdata_compare_cb compare,
139 batadv_hashdata_choose_cb choose,
140 void *data)
141 {
142 u32 index;
143 struct hlist_node *node;
144 struct hlist_head *head;
145 void *data_save = NULL;
146
147 index = choose(data, hash->size);
148 head = &hash->table[index];
149
150 spin_lock_bh(&hash->list_locks[index]);
151 hlist_for_each(node, head) {
152 if (!compare(node, data))
153 continue;
154
155 data_save = node;
156 hlist_del_rcu(node);
157 break;
158 }
159 spin_unlock_bh(&hash->list_locks[index]);
160
161 return data_save;
162 }
163
164 #endif /* _NET_BATMAN_ADV_HASH_H_ */
165
