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
7 #ifndef _NET_BATMAN_ADV_HASH_H_
8 #define _NET_BATMAN_ADV_HASH_H_
9
10 #include "main.h"
11
12 #include <linux/atomic.h>
13 #include <linux/compiler.h>
14 #include <linux/list.h>
15 #include <linux/lockdep.h>
16 #include <linux/rculist.h>
17 #include <linux/spinlock.h>
18 #include <linux/stddef.h>
19 #include <linux/types.h>
20
21 /* callback to a compare function. should compare 2 element datas for their
22 * keys
23 *
24 * Return: true if same and false if not same
25 */
26 typedef bool (*batadv_hashdata_compare_cb)(const struct hlist_node *,
27 const void *);
28
29 /* the hashfunction
30 *
31 * Return: an index based on the key in the data of the first argument and the
32 * size the second
33 */
34 typedef u32 (*batadv_hashdata_choose_cb)(const void *, u32);
35 typedef void (*batadv_hashdata_free_cb)(struct hlist_node *, void *);
36
37 /**
38 * struct batadv_hashtable - Wrapper of simple hlist based hashtable
39 */
40 struct batadv_hashtable {
41 /** @table: the hashtable itself with the buckets */
42 struct hlist_head *table;
43
44 /** @list_locks: spinlock for each hash list entry */
45 spinlock_t *list_locks;
46
47 /** @size: size of hashtable */
48 u32 size;
49
50 /** @generation: current (generation) sequence number */
51 atomic_t generation;
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 /**
65 * batadv_hash_add() - adds data to the hashtable
66 * @hash: storage hash table
67 * @compare: callback to determine if 2 hash elements are identical
68 * @choose: callback calculating the hash index
69 * @data: data passed to the aforementioned callbacks as argument
70 * @data_node: to be added element
71 *
72 * Return: 0 on success, 1 if the element already is in the hash
73 * and -1 on error.
74 */
75 static inline int batadv_hash_add(struct batadv_hashtable *hash,
76 batadv_hashdata_compare_cb compare,
77 batadv_hashdata_choose_cb choose,
78 const void *data,
79 struct hlist_node *data_node)
80 {
81 u32 index;
82 int ret = -1;
83 struct hlist_head *head;
84 struct hlist_node *node;
85 spinlock_t *list_lock; /* spinlock to protect write access */
86
87 if (!hash)
88 goto out;
89
90 index = choose(data, hash->size);
91 head = &hash->table[index];
92 list_lock = &hash->list_locks[index];
93
94 spin_lock_bh(list_lock);
95
96 hlist_for_each(node, head) {
97 if (!compare(node, data))
98 continue;
99
100 ret = 1;
101 goto unlock;
102 }
103
104 /* no duplicate found in list, add new element */
105 hlist_add_head_rcu(data_node, head);
106 atomic_inc(&hash->generation);
107
108 ret = 0;
109
110 unlock:
111 spin_unlock_bh(list_lock);
112 out:
113 return ret;
114 }
115
116 /**
117 * batadv_hash_remove() - Removes data from hash, if found
118 * @hash: hash table
119 * @compare: callback to determine if 2 hash elements are identical
120 * @choose: callback calculating the hash index
121 * @data: data passed to the aforementioned callbacks as argument
122 *
123 * ata could be the structure you use with just the key filled, we just need
124 * the key for comparing.
125 *
126 * Return: returns pointer do data on success, so you can remove the used
127 * structure yourself, or NULL on error
128 */
129 static inline void *batadv_hash_remove(struct batadv_hashtable *hash,
130 batadv_hashdata_compare_cb compare,
131 batadv_hashdata_choose_cb choose,
132 void *data)
133 {
134 u32 index;
135 struct hlist_node *node;
136 struct hlist_head *head;
137 void *data_save = NULL;
138
139 index = choose(data, hash->size);
140 head = &hash->table[index];
141
142 spin_lock_bh(&hash->list_locks[index]);
143 hlist_for_each(node, head) {
144 if (!compare(node, data))
145 continue;
146
147 data_save = node;
148 hlist_del_rcu(node);
149 atomic_inc(&hash->generation);
150 break;
151 }
152 spin_unlock_bh(&hash->list_locks[index]);
153
154 return data_save;
155 }
156
157 #endif /* _NET_BATMAN_ADV_HASH_H_ */