1 /* SPDX-License-Identifier: GPL-2.0 */ 2 /* Copyright (C) 2006-2019 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/atomic.h> 25 #include <linux/compiler.h> 26 #include <linux/list.h> 27 #include <linux/rculist.h> 28 #include <linux/spinlock.h> 29 #include <linux/stddef.h> 30 #include <linux/types.h> 31 32 struct lock_class_key; 33 34 /* callback to a compare function. should compare 2 element datas for their 35 * keys 36 * 37 * Return: true if same and false if not same 38 */ 39 typedef bool (*batadv_hashdata_compare_cb)(const struct hlist_node *, 40 const void *); 41 42 /* the hashfunction 43 * 44 * Return: an index based on the key in the data of the first argument and the 45 * size the second 46 */ 47 typedef u32 (*batadv_hashdata_choose_cb)(const void *, u32); 48 typedef void (*batadv_hashdata_free_cb)(struct hlist_node *, void *); 49 50 /** 51 * struct batadv_hashtable - Wrapper of simple hlist based hashtable 52 */ 53 struct batadv_hashtable { 54 /** @table: the hashtable itself with the buckets */ 55 struct hlist_head *table; 56 57 /** @list_locks: spinlock for each hash list entry */ 58 spinlock_t *list_locks; 59 60 /** @size: size of hashtable */ 61 u32 size; 62 63 /** @generation: current (generation) sequence number */ 64 atomic_t generation; 65 }; 66 67 /* allocates and clears the hash */ 68 struct batadv_hashtable *batadv_hash_new(u32 size); 69 70 /* set class key for all locks */ 71 void batadv_hash_set_lock_class(struct batadv_hashtable *hash, 72 struct lock_class_key *key); 73 74 /* free only the hashtable and the hash itself. */ 75 void batadv_hash_destroy(struct batadv_hashtable *hash); 76 77 /** 78 * batadv_hash_add() - adds data to the hashtable 79 * @hash: storage hash table 80 * @compare: callback to determine if 2 hash elements are identical 81 * @choose: callback calculating the hash index 82 * @data: data passed to the aforementioned callbacks as argument 83 * @data_node: to be added element 84 * 85 * Return: 0 on success, 1 if the element already is in the hash 86 * and -1 on error. 87 */ 88 static inline int batadv_hash_add(struct batadv_hashtable *hash, 89 batadv_hashdata_compare_cb compare, 90 batadv_hashdata_choose_cb choose, 91 const void *data, 92 struct hlist_node *data_node) 93 { 94 u32 index; 95 int ret = -1; 96 struct hlist_head *head; 97 struct hlist_node *node; 98 spinlock_t *list_lock; /* spinlock to protect write access */ 99 100 if (!hash) 101 goto out; 102 103 index = choose(data, hash->size); 104 head = &hash->table[index]; 105 list_lock = &hash->list_locks[index]; 106 107 spin_lock_bh(list_lock); 108 109 hlist_for_each(node, head) { 110 if (!compare(node, data)) 111 continue; 112 113 ret = 1; 114 goto unlock; 115 } 116 117 /* no duplicate found in list, add new element */ 118 hlist_add_head_rcu(data_node, head); 119 atomic_inc(&hash->generation); 120 121 ret = 0; 122 123 unlock: 124 spin_unlock_bh(list_lock); 125 out: 126 return ret; 127 } 128 129 /** 130 * batadv_hash_remove() - Removes data from hash, if found 131 * @hash: hash table 132 * @compare: callback to determine if 2 hash elements are identical 133 * @choose: callback calculating the hash index 134 * @data: data passed to the aforementioned callbacks as argument 135 * 136 * ata could be the structure you use with just the key filled, we just need 137 * the key for comparing. 138 * 139 * Return: returns pointer do data on success, so you can remove the used 140 * structure yourself, or NULL on error 141 */ 142 static inline void *batadv_hash_remove(struct batadv_hashtable *hash, 143 batadv_hashdata_compare_cb compare, 144 batadv_hashdata_choose_cb choose, 145 void *data) 146 { 147 u32 index; 148 struct hlist_node *node; 149 struct hlist_head *head; 150 void *data_save = NULL; 151 152 index = choose(data, hash->size); 153 head = &hash->table[index]; 154 155 spin_lock_bh(&hash->list_locks[index]); 156 hlist_for_each(node, head) { 157 if (!compare(node, data)) 158 continue; 159 160 data_save = node; 161 hlist_del_rcu(node); 162 atomic_inc(&hash->generation); 163 break; 164 } 165 spin_unlock_bh(&hash->list_locks[index]); 166 167 return data_save; 168 } 169 170 #endif /* _NET_BATMAN_ADV_HASH_H_ */ 171