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 */
31 typedef int (*hashdata_compare_cb)(struct hlist_node *, 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 */
36 typedef int (*hashdata_choose_cb)(void *, int);
37 typedef void (*hashdata_free_cb)(struct hlist_node *, void *);
38
39 struct 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 */
46 struct hashtable_t *hash_new(int size);
47
48 /* free only the hashtable and the hash itself. */
49 void 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. */
hash_delete(struct hashtable_t * hash,hashdata_free_cb free_cb,void * arg)54 static 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 /* adds data to the hashtable. returns 0 on success, -1 on error */
hash_add(struct hashtable_t * hash,hashdata_compare_cb compare,hashdata_choose_cb choose,void * data,struct hlist_node * data_node)80 static inline int hash_add(struct hashtable_t *hash,
81 hashdata_compare_cb compare,
82 hashdata_choose_cb choose,
83 void *data, struct hlist_node *data_node)
84 {
85 int index;
86 struct hlist_head *head;
87 struct hlist_node *node;
88 spinlock_t *list_lock; /* spinlock to protect write access */
89
90 if (!hash)
91 goto err;
92
93 index = choose(data, hash->size);
94 head = &hash->table[index];
95 list_lock = &hash->list_locks[index];
96
97 rcu_read_lock();
98 __hlist_for_each_rcu(node, head) {
99 if (!compare(node, data))
100 continue;
101
102 goto err_unlock;
103 }
104 rcu_read_unlock();
105
106 /* no duplicate found in list, add new element */
107 spin_lock_bh(list_lock);
108 hlist_add_head_rcu(data_node, head);
109 spin_unlock_bh(list_lock);
110
111 return 0;
112
113 err_unlock:
114 rcu_read_unlock();
115 err:
116 return -1;
117 }
118
119 /* removes data from hash, if found. returns pointer do data on success, so you
120 * can remove the used structure yourself, or NULL on error . data could be the
121 * structure you use with just the key filled, we just need the key for
122 * comparing. */
hash_remove(struct hashtable_t * hash,hashdata_compare_cb compare,hashdata_choose_cb choose,void * data)123 static inline void *hash_remove(struct hashtable_t *hash,
124 hashdata_compare_cb compare,
125 hashdata_choose_cb choose, void *data)
126 {
127 size_t index;
128 struct hlist_node *node;
129 struct hlist_head *head;
130 void *data_save = NULL;
131
132 index = choose(data, hash->size);
133 head = &hash->table[index];
134
135 spin_lock_bh(&hash->list_locks[index]);
136 hlist_for_each(node, head) {
137 if (!compare(node, data))
138 continue;
139
140 data_save = node;
141 hlist_del_rcu(node);
142 break;
143 }
144 spin_unlock_bh(&hash->list_locks[index]);
145
146 return data_save;
147 }
148
149 #endif /* _NET_BATMAN_ADV_HASH_H_ */
150