1 /* Copyright (C) 2006-2012 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_add - adds data to the hashtable 86 * @hash: storage hash table 87 * @compare: callback to determine if 2 hash elements are identical 88 * @choose: callback calculating the hash index 89 * @data: data passed to the aforementioned callbacks as argument 90 * @data_node: to be added element 91 * 92 * Returns 0 on success, 1 if the element already is in the hash 93 * and -1 on error. 94 */ 95 static inline int batadv_hash_add(struct batadv_hashtable *hash, 96 batadv_hashdata_compare_cb compare, 97 batadv_hashdata_choose_cb choose, 98 const void *data, 99 struct hlist_node *data_node) 100 { 101 uint32_t index; 102 int ret = -1; 103 struct hlist_head *head; 104 struct hlist_node *node; 105 spinlock_t *list_lock; /* spinlock to protect write access */ 106 107 if (!hash) 108 goto out; 109 110 index = choose(data, hash->size); 111 head = &hash->table[index]; 112 list_lock = &hash->list_locks[index]; 113 114 spin_lock_bh(list_lock); 115 116 hlist_for_each(node, head) { 117 if (!compare(node, data)) 118 continue; 119 120 ret = 1; 121 goto unlock; 122 } 123 124 /* no duplicate found in list, add new element */ 125 hlist_add_head_rcu(data_node, head); 126 127 ret = 0; 128 129 unlock: 130 spin_unlock_bh(list_lock); 131 out: 132 return ret; 133 } 134 135 /* removes data from hash, if found. returns pointer do data on success, so you 136 * can remove the used structure yourself, or NULL on error . data could be the 137 * structure you use with just the key filled, we just need the key for 138 * comparing. 139 */ 140 static inline void *batadv_hash_remove(struct batadv_hashtable *hash, 141 batadv_hashdata_compare_cb compare, 142 batadv_hashdata_choose_cb choose, 143 void *data) 144 { 145 uint32_t index; 146 struct hlist_node *node; 147 struct hlist_head *head; 148 void *data_save = NULL; 149 150 index = choose(data, hash->size); 151 head = &hash->table[index]; 152 153 spin_lock_bh(&hash->list_locks[index]); 154 hlist_for_each(node, head) { 155 if (!compare(node, data)) 156 continue; 157 158 data_save = node; 159 hlist_del_rcu(node); 160 break; 161 } 162 spin_unlock_bh(&hash->list_locks[index]); 163 164 return data_save; 165 } 166 167 #endif /* _NET_BATMAN_ADV_HASH_H_ */ 168