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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/rculist.h>
16#include <linux/spinlock.h>
17#include <linux/stddef.h>
18#include <linux/types.h>
19
20struct lock_class_key;
21
22/* callback to a compare function. should compare 2 element datas for their
23 * keys
24 *
25 * Return: true if same and false if not same
26 */
27typedef bool (*batadv_hashdata_compare_cb)(const struct hlist_node *,
28 const void *);
29
30/* the hashfunction
31 *
32 * Return: an index based on the key in the data of the first argument and the
33 * size the second
34 */
35typedef u32 (*batadv_hashdata_choose_cb)(const void *, u32);
36typedef void (*batadv_hashdata_free_cb)(struct hlist_node *, void *);
37
38/**
39 * struct batadv_hashtable - Wrapper of simple hlist based hashtable
40 */
41struct batadv_hashtable {
42 /** @table: the hashtable itself with the buckets */
43 struct hlist_head *table;
44
45 /** @list_locks: spinlock for each hash list entry */
46 spinlock_t *list_locks;
47
48 /** @size: size of hashtable */
49 u32 size;
50
51 /** @generation: current (generation) sequence number */
52 atomic_t generation;
53};
54
55/* allocates and clears the hash */
56struct batadv_hashtable *batadv_hash_new(u32 size);
57
58/* set class key for all locks */
59void batadv_hash_set_lock_class(struct batadv_hashtable *hash,
60 struct lock_class_key *key);
61
62/* free only the hashtable and the hash itself. */
63void batadv_hash_destroy(struct batadv_hashtable *hash);
64
65/**
66 * batadv_hash_add() - adds data to the hashtable
67 * @hash: storage hash table
68 * @compare: callback to determine if 2 hash elements are identical
69 * @choose: callback calculating the hash index
70 * @data: data passed to the aforementioned callbacks as argument
71 * @data_node: to be added element
72 *
73 * Return: 0 on success, 1 if the element already is in the hash
74 * and -1 on error.
75 */
76static inline int batadv_hash_add(struct batadv_hashtable *hash,
77 batadv_hashdata_compare_cb compare,
78 batadv_hashdata_choose_cb choose,
79 const void *data,
80 struct hlist_node *data_node)
81{
82 u32 index;
83 int ret = -1;
84 struct hlist_head *head;
85 struct hlist_node *node;
86 spinlock_t *list_lock; /* spinlock to protect write access */
87
88 if (!hash)
89 goto out;
90
91 index = choose(data, hash->size);
92 head = &hash->table[index];
93 list_lock = &hash->list_locks[index];
94
95 spin_lock_bh(list_lock);
96
97 hlist_for_each(node, head) {
98 if (!compare(node, data))
99 continue;
100
101 ret = 1;
102 goto unlock;
103 }
104
105 /* no duplicate found in list, add new element */
106 hlist_add_head_rcu(data_node, head);
107 atomic_inc(&hash->generation);
108
109 ret = 0;
110
111unlock:
112 spin_unlock_bh(list_lock);
113out:
114 return ret;
115}
116
117/**
118 * batadv_hash_remove() - Removes data from hash, if found
119 * @hash: hash table
120 * @compare: callback to determine if 2 hash elements are identical
121 * @choose: callback calculating the hash index
122 * @data: data passed to the aforementioned callbacks as argument
123 *
124 * ata could be the structure you use with just the key filled, we just need
125 * the key for comparing.
126 *
127 * Return: returns pointer do data on success, so you can remove the used
128 * structure yourself, or NULL on error
129 */
130static inline void *batadv_hash_remove(struct batadv_hashtable *hash,
131 batadv_hashdata_compare_cb compare,
132 batadv_hashdata_choose_cb choose,
133 void *data)
134{
135 u32 index;
136 struct hlist_node *node;
137 struct hlist_head *head;
138 void *data_save = NULL;
139
140 index = choose(data, hash->size);
141 head = &hash->table[index];
142
143 spin_lock_bh(&hash->list_locks[index]);
144 hlist_for_each(node, head) {
145 if (!compare(node, data))
146 continue;
147
148 data_save = node;
149 hlist_del_rcu(node);
150 atomic_inc(&hash->generation);
151 break;
152 }
153 spin_unlock_bh(&hash->list_locks[index]);
154
155 return data_save;
156}
157
158#endif /* _NET_BATMAN_ADV_HASH_H_ */