1 /* Copyright (C) 2006-2016 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, see <http://www.gnu.org/licenses/>. 16 */ 17 18 #ifndef _NET_BATMAN_ADV_HASH_H_ 19 #define _NET_BATMAN_ADV_HASH_H_ 20 21 #include "main.h" 22 23 #include <linux/compiler.h> 24 #include <linux/list.h> 25 #include <linux/rculist.h> 26 #include <linux/spinlock.h> 27 #include <linux/stddef.h> 28 #include <linux/types.h> 29 30 struct lock_class_key; 31 32 /* callback to a compare function. should compare 2 element datas for their 33 * keys 34 * 35 * Return: true if same and false if not same 36 */ 37 typedef bool (*batadv_hashdata_compare_cb)(const struct hlist_node *, 38 const void *); 39 40 /* the hashfunction 41 * 42 * Return: an index based on the key in the data of the first argument and the 43 * size the second 44 */ 45 typedef u32 (*batadv_hashdata_choose_cb)(const void *, u32); 46 typedef void (*batadv_hashdata_free_cb)(struct hlist_node *, void *); 47 48 struct batadv_hashtable { 49 struct hlist_head *table; /* the hashtable itself with the buckets */ 50 spinlock_t *list_locks; /* spinlock for each hash list entry */ 51 u32 size; /* size of hashtable */ 52 }; 53 54 /* allocates and clears the hash */ 55 struct batadv_hashtable *batadv_hash_new(u32 size); 56 57 /* set class key for all locks */ 58 void batadv_hash_set_lock_class(struct batadv_hashtable *hash, 59 struct lock_class_key *key); 60 61 /* free only the hashtable and the hash itself. */ 62 void batadv_hash_destroy(struct batadv_hashtable *hash); 63 64 /** 65 * batadv_hash_add - adds data to the hashtable 66 * @hash: storage hash table 67 * @compare: callback to determine if 2 hash elements are identical 68 * @choose: callback calculating the hash index 69 * @data: data passed to the aforementioned callbacks as argument 70 * @data_node: to be added element 71 * 72 * Return: 0 on success, 1 if the element already is in the hash 73 * and -1 on error. 74 */ 75 static inline int batadv_hash_add(struct batadv_hashtable *hash, 76 batadv_hashdata_compare_cb compare, 77 batadv_hashdata_choose_cb choose, 78 const void *data, 79 struct hlist_node *data_node) 80 { 81 u32 index; 82 int ret = -1; 83 struct hlist_head *head; 84 struct hlist_node *node; 85 spinlock_t *list_lock; /* spinlock to protect write access */ 86 87 if (!hash) 88 goto out; 89 90 index = choose(data, hash->size); 91 head = &hash->table[index]; 92 list_lock = &hash->list_locks[index]; 93 94 spin_lock_bh(list_lock); 95 96 hlist_for_each(node, head) { 97 if (!compare(node, data)) 98 continue; 99 100 ret = 1; 101 goto unlock; 102 } 103 104 /* no duplicate found in list, add new element */ 105 hlist_add_head_rcu(data_node, head); 106 107 ret = 0; 108 109 unlock: 110 spin_unlock_bh(list_lock); 111 out: 112 return ret; 113 } 114 115 /* removes data from hash, if found. data could be the structure you use with 116 * just the key filled, we just need the key for comparing. 117 * 118 * Return: returns pointer do data on success, so you can remove the used 119 * structure yourself, or NULL on error 120 */ 121 static inline void *batadv_hash_remove(struct batadv_hashtable *hash, 122 batadv_hashdata_compare_cb compare, 123 batadv_hashdata_choose_cb choose, 124 void *data) 125 { 126 u32 index; 127 struct hlist_node *node; 128 struct hlist_head *head; 129 void *data_save = NULL; 130 131 index = choose(data, hash->size); 132 head = &hash->table[index]; 133 134 spin_lock_bh(&hash->list_locks[index]); 135 hlist_for_each(node, head) { 136 if (!compare(node, data)) 137 continue; 138 139 data_save = node; 140 hlist_del_rcu(node); 141 break; 142 } 143 spin_unlock_bh(&hash->list_locks[index]); 144 145 return data_save; 146 } 147 148 #endif /* _NET_BATMAN_ADV_HASH_H_ */ 149