tjh.dev
Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
1/*
2 * Copyright (C) 2006-2011 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, write to the Free Software
17 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
18 * 02110-1301, USA
19 *
20 */
21
22#ifndef _NET_BATMAN_ADV_HASH_H_
23#define _NET_BATMAN_ADV_HASH_H_
24
25#include <linux/list.h>
26
27/* callback to a compare function. should
28 * compare 2 element datas for their keys,
29 * return 0 if same and not 0 if not
30 * same */
31typedef int (*hashdata_compare_cb)(const struct hlist_node *, const void *);
32
33/* the hashfunction, should return an index
34 * based on the key in the data of the first
35 * argument and the size the second */
36typedef int (*hashdata_choose_cb)(const void *, int);
37typedef void (*hashdata_free_cb)(struct hlist_node *, void *);
38
39struct hashtable_t {
40 struct hlist_head *table; /* the hashtable itself with the buckets */
41 spinlock_t *list_locks; /* spinlock for each hash list entry */
42 int size; /* size of hashtable */
43};
44
45/* allocates and clears the hash */
46struct hashtable_t *hash_new(int size);
47
48/* free only the hashtable and the hash itself. */
49void hash_destroy(struct hashtable_t *hash);
50
51/* remove the hash structure. if hashdata_free_cb != NULL, this function will be
52 * called to remove the elements inside of the hash. if you don't remove the
53 * elements, memory might be leaked. */
54static inline void hash_delete(struct hashtable_t *hash,
55 hashdata_free_cb free_cb, void *arg)
56{
57 struct hlist_head *head;
58 struct hlist_node *node, *node_tmp;
59 spinlock_t *list_lock; /* spinlock to protect write access */
60 int i;
61
62 for (i = 0; i < hash->size; i++) {
63 head = &hash->table[i];
64 list_lock = &hash->list_locks[i];
65
66 spin_lock_bh(list_lock);
67 hlist_for_each_safe(node, node_tmp, head) {
68 hlist_del_rcu(node);
69
70 if (free_cb)
71 free_cb(node, arg);
72 }
73 spin_unlock_bh(list_lock);
74 }
75
76 hash_destroy(hash);
77}
78
79/**
80 * hash_add - adds data to the hashtable
81 * @hash: storage hash table
82 * @compare: callback to determine if 2 hash elements are identical
83 * @choose: callback calculating the hash index
84 * @data: data passed to the aforementioned callbacks as argument
85 * @data_node: to be added element
86 *
87 * Returns 0 on success, 1 if the element already is in the hash
88 * and -1 on error.
89 */
90
91static inline int hash_add(struct hashtable_t *hash,
92 hashdata_compare_cb compare,
93 hashdata_choose_cb choose,
94 const void *data, struct hlist_node *data_node)
95{
96 int index, ret = -1;
97 struct hlist_head *head;
98 struct hlist_node *node;
99 spinlock_t *list_lock; /* spinlock to protect write access */
100
101 if (!hash)
102 goto out;
103
104 index = choose(data, hash->size);
105 head = &hash->table[index];
106 list_lock = &hash->list_locks[index];
107
108 rcu_read_lock();
109 __hlist_for_each_rcu(node, head) {
110 if (!compare(node, data))
111 continue;
112
113 ret = 1;
114 goto err_unlock;
115 }
116 rcu_read_unlock();
117
118 /* no duplicate found in list, add new element */
119 spin_lock_bh(list_lock);
120 hlist_add_head_rcu(data_node, head);
121 spin_unlock_bh(list_lock);
122
123 ret = 0;
124 goto out;
125
126err_unlock:
127 rcu_read_unlock();
128out:
129 return ret;
130}
131
132/* removes data from hash, if found. returns pointer do data on success, so you
133 * can remove the used structure yourself, or NULL on error . data could be the
134 * structure you use with just the key filled, we just need the key for
135 * comparing. */
136static inline void *hash_remove(struct hashtable_t *hash,
137 hashdata_compare_cb compare,
138 hashdata_choose_cb choose, void *data)
139{
140 size_t index;
141 struct hlist_node *node;
142 struct hlist_head *head;
143 void *data_save = NULL;
144
145 index = choose(data, hash->size);
146 head = &hash->table[index];
147
148 spin_lock_bh(&hash->list_locks[index]);
149 hlist_for_each(node, head) {
150 if (!compare(node, data))
151 continue;
152
153 data_save = node;
154 hlist_del_rcu(node);
155 break;
156 }
157 spin_unlock_bh(&hash->list_locks[index]);
158
159 return data_save;
160}
161
162#endif /* _NET_BATMAN_ADV_HASH_H_ */