1 /*
2 * Copyright (C) 2006-2012 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)(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 */
36 typedef uint32_t (*hashdata_choose_cb)(const void *, uint32_t);
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 uint32_t size; /* size of hashtable */
43 };
44
45 /* allocates and clears the hash */
46 struct hashtable_t *hash_new(uint32_t 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 uint32_t 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
hash_add(struct hashtable_t * hash,hashdata_compare_cb compare,hashdata_choose_cb choose,const void * data,struct hlist_node * data_node)91 static 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 uint32_t index;
97 int ret = -1;
98 struct hlist_head *head;
99 struct hlist_node *node;
100 spinlock_t *list_lock; /* spinlock to protect write access */
101
102 if (!hash)
103 goto out;
104
105 index = choose(data, hash->size);
106 head = &hash->table[index];
107 list_lock = &hash->list_locks[index];
108
109 rcu_read_lock();
110 __hlist_for_each_rcu(node, head) {
111 if (!compare(node, data))
112 continue;
113
114 ret = 1;
115 goto err_unlock;
116 }
117 rcu_read_unlock();
118
119 /* no duplicate found in list, add new element */
120 spin_lock_bh(list_lock);
121 hlist_add_head_rcu(data_node, head);
122 spin_unlock_bh(list_lock);
123
124 ret = 0;
125 goto out;
126
127 err_unlock:
128 rcu_read_unlock();
129 out:
130 return ret;
131 }
132
133 /* removes data from hash, if found. returns pointer do data on success, so you
134 * can remove the used structure yourself, or NULL on error . data could be the
135 * structure you use with just the key filled, we just need the key for
136 * comparing. */
hash_remove(struct hashtable_t * hash,hashdata_compare_cb compare,hashdata_choose_cb choose,void * data)137 static inline void *hash_remove(struct hashtable_t *hash,
138 hashdata_compare_cb compare,
139 hashdata_choose_cb choose, void *data)
140 {
141 uint32_t index;
142 struct hlist_node *node;
143 struct hlist_head *head;
144 void *data_save = NULL;
145
146 index = choose(data, hash->size);
147 head = &hash->table[index];
148
149 spin_lock_bh(&hash->list_locks[index]);
150 hlist_for_each(node, head) {
151 if (!compare(node, data))
152 continue;
153
154 data_save = node;
155 hlist_del_rcu(node);
156 break;
157 }
158 spin_unlock_bh(&hash->list_locks[index]);
159
160 return data_save;
161 }
162
163 #endif /* _NET_BATMAN_ADV_HASH_H_ */
164