1 /* SPDX-License-Identifier: GPL-2.0 */
2 /* Copyright (C) 2006-2019 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/atomic.h>
25 #include <linux/compiler.h>
26 #include <linux/list.h>
27 #include <linux/rculist.h>
28 #include <linux/spinlock.h>
29 #include <linux/stddef.h>
30 #include <linux/types.h>
31
32 struct lock_class_key;
33
34 /* callback to a compare function. should compare 2 element datas for their
35 * keys
36 *
37 * Return: true if same and false if not same
38 */
39 typedef bool (*batadv_hashdata_compare_cb)(const struct hlist_node *,
40 const void *);
41
42 /* the hashfunction
43 *
44 * Return: an index based on the key in the data of the first argument and the
45 * size the second
46 */
47 typedef u32 (*batadv_hashdata_choose_cb)(const void *, u32);
48 typedef void (*batadv_hashdata_free_cb)(struct hlist_node *, void *);
49
50 /**
51 * struct batadv_hashtable - Wrapper of simple hlist based hashtable
52 */
53 struct batadv_hashtable {
54 /** @table: the hashtable itself with the buckets */
55 struct hlist_head *table;
56
57 /** @list_locks: spinlock for each hash list entry */
58 spinlock_t *list_locks;
59
60 /** @size: size of hashtable */
61 u32 size;
62
63 /** @generation: current (generation) sequence number */
64 atomic_t generation;
65 };
66
67 /* allocates and clears the hash */
68 struct batadv_hashtable *batadv_hash_new(u32 size);
69
70 /* set class key for all locks */
71 void batadv_hash_set_lock_class(struct batadv_hashtable *hash,
72 struct lock_class_key *key);
73
74 /* free only the hashtable and the hash itself. */
75 void batadv_hash_destroy(struct batadv_hashtable *hash);
76
77 /**
78 * batadv_hash_add() - adds data to the hashtable
79 * @hash: storage hash table
80 * @compare: callback to determine if 2 hash elements are identical
81 * @choose: callback calculating the hash index
82 * @data: data passed to the aforementioned callbacks as argument
83 * @data_node: to be added element
84 *
85 * Return: 0 on success, 1 if the element already is in the hash
86 * and -1 on error.
87 */
88 static inline int batadv_hash_add(struct batadv_hashtable *hash,
89 batadv_hashdata_compare_cb compare,
90 batadv_hashdata_choose_cb choose,
91 const void *data,
92 struct hlist_node *data_node)
93 {
94 u32 index;
95 int ret = -1;
96 struct hlist_head *head;
97 struct hlist_node *node;
98 spinlock_t *list_lock; /* spinlock to protect write access */
99
100 if (!hash)
101 goto out;
102
103 index = choose(data, hash->size);
104 head = &hash->table[index];
105 list_lock = &hash->list_locks[index];
106
107 spin_lock_bh(list_lock);
108
109 hlist_for_each(node, head) {
110 if (!compare(node, data))
111 continue;
112
113 ret = 1;
114 goto unlock;
115 }
116
117 /* no duplicate found in list, add new element */
118 hlist_add_head_rcu(data_node, head);
119 atomic_inc(&hash->generation);
120
121 ret = 0;
122
123 unlock:
124 spin_unlock_bh(list_lock);
125 out:
126 return ret;
127 }
128
129 /**
130 * batadv_hash_remove() - Removes data from hash, if found
131 * @hash: hash table
132 * @compare: callback to determine if 2 hash elements are identical
133 * @choose: callback calculating the hash index
134 * @data: data passed to the aforementioned callbacks as argument
135 *
136 * ata could be the structure you use with just the key filled, we just need
137 * the key for comparing.
138 *
139 * Return: returns pointer do data on success, so you can remove the used
140 * structure yourself, or NULL on error
141 */
142 static inline void *batadv_hash_remove(struct batadv_hashtable *hash,
143 batadv_hashdata_compare_cb compare,
144 batadv_hashdata_choose_cb choose,
145 void *data)
146 {
147 u32 index;
148 struct hlist_node *node;
149 struct hlist_head *head;
150 void *data_save = NULL;
151
152 index = choose(data, hash->size);
153 head = &hash->table[index];
154
155 spin_lock_bh(&hash->list_locks[index]);
156 hlist_for_each(node, head) {
157 if (!compare(node, data))
158 continue;
159
160 data_save = node;
161 hlist_del_rcu(node);
162 atomic_inc(&hash->generation);
163 break;
164 }
165 spin_unlock_bh(&hash->list_locks[index]);
166
167 return data_save;
168 }
169
170 #endif /* _NET_BATMAN_ADV_HASH_H_ */
171
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