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TOMOYO Linux Cross Reference
Linux/net/batman-adv/hash.h

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  1 /* Copyright (C) 2006-2013 B.A.T.M.A.N. contributors:
  2  *
  3  * Simon Wunderlich, Marek Lindner
  4  *
  5  * This program is free software; you can redistribute it and/or
  6  * modify it under the terms of version 2 of the GNU General Public
  7  * License as published by the Free Software Foundation.
  8  *
  9  * This program is distributed in the hope that it will be useful, but
 10  * WITHOUT ANY WARRANTY; without even the implied warranty of
 11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
 12  * General Public License for more details.
 13  *
 14  * You should have received a copy of the GNU General Public License
 15  * along with this program; if not, write to the Free Software
 16  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
 17  * 02110-1301, USA
 18  */
 19 
 20 #ifndef _NET_BATMAN_ADV_HASH_H_
 21 #define _NET_BATMAN_ADV_HASH_H_
 22 
 23 #include <linux/list.h>
 24 
 25 /* callback to a compare function.  should compare 2 element datas for their
 26  * keys, return 0 if same and not 0 if not same
 27  */
 28 typedef int (*batadv_hashdata_compare_cb)(const struct hlist_node *,
 29                                           const void *);
 30 
 31 /* the hashfunction, should return an index
 32  * based on the key in the data of the first
 33  * argument and the size the second
 34  */
 35 typedef uint32_t (*batadv_hashdata_choose_cb)(const void *, uint32_t);
 36 typedef void (*batadv_hashdata_free_cb)(struct hlist_node *, void *);
 37 
 38 struct batadv_hashtable {
 39         struct hlist_head *table;   /* the hashtable itself with the buckets */
 40         spinlock_t *list_locks;     /* spinlock for each hash list entry */
 41         uint32_t size;              /* size of hashtable */
 42 };
 43 
 44 /* allocates and clears the hash */
 45 struct batadv_hashtable *batadv_hash_new(uint32_t size);
 46 
 47 /* set class key for all locks */
 48 void batadv_hash_set_lock_class(struct batadv_hashtable *hash,
 49                                 struct lock_class_key *key);
 50 
 51 /* free only the hashtable and the hash itself. */
 52 void batadv_hash_destroy(struct batadv_hashtable *hash);
 53 
 54 /* remove the hash structure. if hashdata_free_cb != NULL, this function will be
 55  * called to remove the elements inside of the hash.  if you don't remove the
 56  * elements, memory might be leaked.
 57  */
 58 static inline void batadv_hash_delete(struct batadv_hashtable *hash,
 59                                       batadv_hashdata_free_cb free_cb,
 60                                       void *arg)
 61 {
 62         struct hlist_head *head;
 63         struct hlist_node *node, *node_tmp;
 64         spinlock_t *list_lock; /* spinlock to protect write access */
 65         uint32_t i;
 66 
 67         for (i = 0; i < hash->size; i++) {
 68                 head = &hash->table[i];
 69                 list_lock = &hash->list_locks[i];
 70 
 71                 spin_lock_bh(list_lock);
 72                 hlist_for_each_safe(node, node_tmp, head) {
 73                         hlist_del_rcu(node);
 74 
 75                         if (free_cb)
 76                                 free_cb(node, arg);
 77                 }
 78                 spin_unlock_bh(list_lock);
 79         }
 80 
 81         batadv_hash_destroy(hash);
 82 }
 83 
 84 /**
 85  *      batadv_hash_bytes - hash some bytes and add them to the previous hash
 86  *      @hash: previous hash value
 87  *      @data: data to be hashed
 88  *      @size: number of bytes to be hashed
 89  *
 90  *      Returns the new hash value.
 91  */
 92 static inline uint32_t batadv_hash_bytes(uint32_t hash, const void *data,
 93                                          uint32_t size)
 94 {
 95         const unsigned char *key = data;
 96         int i;
 97 
 98         for (i = 0; i < size; i++) {
 99                 hash += key[i];
100                 hash += (hash << 10);
101                 hash ^= (hash >> 6);
102         }
103         return hash;
104 }
105 
106 /**
107  *      batadv_hash_add - adds data to the hashtable
108  *      @hash: storage hash table
109  *      @compare: callback to determine if 2 hash elements are identical
110  *      @choose: callback calculating the hash index
111  *      @data: data passed to the aforementioned callbacks as argument
112  *      @data_node: to be added element
113  *
114  *      Returns 0 on success, 1 if the element already is in the hash
115  *      and -1 on error.
116  */
117 static inline int batadv_hash_add(struct batadv_hashtable *hash,
118                                   batadv_hashdata_compare_cb compare,
119                                   batadv_hashdata_choose_cb choose,
120                                   const void *data,
121                                   struct hlist_node *data_node)
122 {
123         uint32_t index;
124         int ret = -1;
125         struct hlist_head *head;
126         struct hlist_node *node;
127         spinlock_t *list_lock; /* spinlock to protect write access */
128 
129         if (!hash)
130                 goto out;
131 
132         index = choose(data, hash->size);
133         head = &hash->table[index];
134         list_lock = &hash->list_locks[index];
135 
136         spin_lock_bh(list_lock);
137 
138         hlist_for_each(node, head) {
139                 if (!compare(node, data))
140                         continue;
141 
142                 ret = 1;
143                 goto unlock;
144         }
145 
146         /* no duplicate found in list, add new element */
147         hlist_add_head_rcu(data_node, head);
148 
149         ret = 0;
150 
151 unlock:
152         spin_unlock_bh(list_lock);
153 out:
154         return ret;
155 }
156 
157 /* removes data from hash, if found. returns pointer do data on success, so you
158  * can remove the used structure yourself, or NULL on error .  data could be the
159  * structure you use with just the key filled, we just need the key for
160  * comparing.
161  */
162 static inline void *batadv_hash_remove(struct batadv_hashtable *hash,
163                                        batadv_hashdata_compare_cb compare,
164                                        batadv_hashdata_choose_cb choose,
165                                        void *data)
166 {
167         uint32_t index;
168         struct hlist_node *node;
169         struct hlist_head *head;
170         void *data_save = NULL;
171 
172         index = choose(data, hash->size);
173         head = &hash->table[index];
174 
175         spin_lock_bh(&hash->list_locks[index]);
176         hlist_for_each(node, head) {
177                 if (!compare(node, data))
178                         continue;
179 
180                 data_save = node;
181                 hlist_del_rcu(node);
182                 break;
183         }
184         spin_unlock_bh(&hash->list_locks[index]);
185 
186         return data_save;
187 }
188 
189 #endif /* _NET_BATMAN_ADV_HASH_H_ */
190 

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