1 /* SPDX-License-Identifier: GPL-2.0 */ 2 /* Copyright (C) 2006-2017 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, see <http://www.gnu.org/licenses/>. 17 */ 18 19 #ifndef _NET_BATMAN_ADV_HASH_H_ 20 #define _NET_BATMAN_ADV_HASH_H_ 21 22 #include "main.h" 23 24 #include <linux/compiler.h> 25 #include <linux/list.h> 26 #include <linux/rculist.h> 27 #include <linux/spinlock.h> 28 #include <linux/stddef.h> 29 #include <linux/types.h> 30 31 struct lock_class_key; 32 33 /* callback to a compare function. should compare 2 element datas for their 34 * keys 35 * 36 * Return: true if same and false if not same 37 */ 38 typedef bool (*batadv_hashdata_compare_cb)(const struct hlist_node *, 39 const void *); 40 41 /* the hashfunction 42 * 43 * Return: an index based on the key in the data of the first argument and the 44 * size the second 45 */ 46 typedef u32 (*batadv_hashdata_choose_cb)(const void *, u32); 47 typedef void (*batadv_hashdata_free_cb)(struct hlist_node *, void *); 48 49 /** 50 * struct batadv_hashtable - Wrapper of simple hlist based hashtable 51 */ 52 struct batadv_hashtable { 53 /** @table: the hashtable itself with the buckets */ 54 struct hlist_head *table; 55 56 /** @list_locks: spinlock for each hash list entry */ 57 spinlock_t *list_locks; 58 59 /** @size: size of hashtable */ 60 u32 size; 61 }; 62 63 /* allocates and clears the hash */ 64 struct batadv_hashtable *batadv_hash_new(u32 size); 65 66 /* set class key for all locks */ 67 void batadv_hash_set_lock_class(struct batadv_hashtable *hash, 68 struct lock_class_key *key); 69 70 /* free only the hashtable and the hash itself. */ 71 void batadv_hash_destroy(struct batadv_hashtable *hash); 72 73 /** 74 * batadv_hash_add() - adds data to the hashtable 75 * @hash: storage hash table 76 * @compare: callback to determine if 2 hash elements are identical 77 * @choose: callback calculating the hash index 78 * @data: data passed to the aforementioned callbacks as argument 79 * @data_node: to be added element 80 * 81 * Return: 0 on success, 1 if the element already is in the hash 82 * and -1 on error. 83 */ 84 static inline int batadv_hash_add(struct batadv_hashtable *hash, 85 batadv_hashdata_compare_cb compare, 86 batadv_hashdata_choose_cb choose, 87 const void *data, 88 struct hlist_node *data_node) 89 { 90 u32 index; 91 int ret = -1; 92 struct hlist_head *head; 93 struct hlist_node *node; 94 spinlock_t *list_lock; /* spinlock to protect write access */ 95 96 if (!hash) 97 goto out; 98 99 index = choose(data, hash->size); 100 head = &hash->table[index]; 101 list_lock = &hash->list_locks[index]; 102 103 spin_lock_bh(list_lock); 104 105 hlist_for_each(node, head) { 106 if (!compare(node, data)) 107 continue; 108 109 ret = 1; 110 goto unlock; 111 } 112 113 /* no duplicate found in list, add new element */ 114 hlist_add_head_rcu(data_node, head); 115 116 ret = 0; 117 118 unlock: 119 spin_unlock_bh(list_lock); 120 out: 121 return ret; 122 } 123 124 /** 125 * batadv_hash_remove() - Removes data from hash, if found 126 * @hash: hash table 127 * @compare: callback to determine if 2 hash elements are identical 128 * @choose: callback calculating the hash index 129 * @data: data passed to the aforementioned callbacks as argument 130 * 131 * ata could be the structure you use with just the key filled, we just need 132 * the key for comparing. 133 * 134 * Return: returns pointer do data on success, so you can remove the used 135 * structure yourself, or NULL on error 136 */ 137 static inline void *batadv_hash_remove(struct batadv_hashtable *hash, 138 batadv_hashdata_compare_cb compare, 139 batadv_hashdata_choose_cb choose, 140 void *data) 141 { 142 u32 index; 143 struct hlist_node *node; 144 struct hlist_head *head; 145 void *data_save = NULL; 146 147 index = choose(data, hash->size); 148 head = &hash->table[index]; 149 150 spin_lock_bh(&hash->list_locks[index]); 151 hlist_for_each(node, head) { 152 if (!compare(node, data)) 153 continue; 154 155 data_save = node; 156 hlist_del_rcu(node); 157 break; 158 } 159 spin_unlock_bh(&hash->list_locks[index]); 160 161 return data_save; 162 } 163 164 #endif /* _NET_BATMAN_ADV_HASH_H_ */ 165