1 /* Copyright (C) 2006-2015 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, return 0 if same and not 0 if not same 34 */ 35 typedef int (*batadv_hashdata_compare_cb)(const struct hlist_node *, 36 const void *); 37 38 /* the hashfunction, should return an index 39 * based on the key in the data of the first 40 * argument and the size the second 41 */ 42 typedef u32 (*batadv_hashdata_choose_cb)(const void *, u32); 43 typedef void (*batadv_hashdata_free_cb)(struct hlist_node *, void *); 44 45 struct batadv_hashtable { 46 struct hlist_head *table; /* the hashtable itself with the buckets */ 47 spinlock_t *list_locks; /* spinlock for each hash list entry */ 48 u32 size; /* size of hashtable */ 49 }; 50 51 /* allocates and clears the hash */ 52 struct batadv_hashtable *batadv_hash_new(u32 size); 53 54 /* set class key for all locks */ 55 void batadv_hash_set_lock_class(struct batadv_hashtable *hash, 56 struct lock_class_key *key); 57 58 /* free only the hashtable and the hash itself. */ 59 void batadv_hash_destroy(struct batadv_hashtable *hash); 60 61 /* remove the hash structure. if hashdata_free_cb != NULL, this function will be 62 * called to remove the elements inside of the hash. if you don't remove the 63 * elements, memory might be leaked. 64 */ 65 static inline void batadv_hash_delete(struct batadv_hashtable *hash, 66 batadv_hashdata_free_cb free_cb, 67 void *arg) 68 { 69 struct hlist_head *head; 70 struct hlist_node *node, *node_tmp; 71 spinlock_t *list_lock; /* spinlock to protect write access */ 72 u32 i; 73 74 for (i = 0; i < hash->size; i++) { 75 head = &hash->table[i]; 76 list_lock = &hash->list_locks[i]; 77 78 spin_lock_bh(list_lock); 79 hlist_for_each_safe(node, node_tmp, head) { 80 hlist_del_rcu(node); 81 82 if (free_cb) 83 free_cb(node, arg); 84 } 85 spin_unlock_bh(list_lock); 86 } 87 88 batadv_hash_destroy(hash); 89 } 90 91 /** 92 * batadv_hash_add - adds data to the hashtable 93 * @hash: storage hash table 94 * @compare: callback to determine if 2 hash elements are identical 95 * @choose: callback calculating the hash index 96 * @data: data passed to the aforementioned callbacks as argument 97 * @data_node: to be added element 98 * 99 * Returns 0 on success, 1 if the element already is in the hash 100 * and -1 on error. 101 */ 102 static inline int batadv_hash_add(struct batadv_hashtable *hash, 103 batadv_hashdata_compare_cb compare, 104 batadv_hashdata_choose_cb choose, 105 const void *data, 106 struct hlist_node *data_node) 107 { 108 u32 index; 109 int ret = -1; 110 struct hlist_head *head; 111 struct hlist_node *node; 112 spinlock_t *list_lock; /* spinlock to protect write access */ 113 114 if (!hash) 115 goto out; 116 117 index = choose(data, hash->size); 118 head = &hash->table[index]; 119 list_lock = &hash->list_locks[index]; 120 121 spin_lock_bh(list_lock); 122 123 hlist_for_each(node, head) { 124 if (!compare(node, data)) 125 continue; 126 127 ret = 1; 128 goto unlock; 129 } 130 131 /* no duplicate found in list, add new element */ 132 hlist_add_head_rcu(data_node, head); 133 134 ret = 0; 135 136 unlock: 137 spin_unlock_bh(list_lock); 138 out: 139 return ret; 140 } 141 142 /* removes data from hash, if found. returns pointer do data on success, so you 143 * can remove the used structure yourself, or NULL on error . data could be the 144 * structure you use with just the key filled, we just need the key for 145 * comparing. 146 */ 147 static inline void *batadv_hash_remove(struct batadv_hashtable *hash, 148 batadv_hashdata_compare_cb compare, 149 batadv_hashdata_choose_cb choose, 150 void *data) 151 { 152 u32 index; 153 struct hlist_node *node; 154 struct hlist_head *head; 155 void *data_save = NULL; 156 157 index = choose(data, hash->size); 158 head = &hash->table[index]; 159 160 spin_lock_bh(&hash->list_locks[index]); 161 hlist_for_each(node, head) { 162 if (!compare(node, data)) 163 continue; 164 165 data_save = node; 166 hlist_del_rcu(node); 167 break; 168 } 169 spin_unlock_bh(&hash->list_locks[index]); 170 171 return data_save; 172 } 173 174 #endif /* _NET_BATMAN_ADV_HASH_H_ */ 175