1 /* 2 * Copyright (C) 2006-2011 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, write to the Free Software 17 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 18 * 02110-1301, USA 19 * 20 */ 21 22 #ifndef _NET_BATMAN_ADV_HASH_H_ 23 #define _NET_BATMAN_ADV_HASH_H_ 24 25 #include <linux/list.h> 26 27 /* callback to a compare function. should 28 * compare 2 element datas for their keys, 29 * return 0 if same and not 0 if not 30 * same */ 31 typedef int (*hashdata_compare_cb)(const struct hlist_node *, const void *); 32 33 /* the hashfunction, should return an index 34 * based on the key in the data of the first 35 * argument and the size the second */ 36 typedef int (*hashdata_choose_cb)(const void *, int); 37 typedef void (*hashdata_free_cb)(struct hlist_node *, void *); 38 39 struct hashtable_t { 40 struct hlist_head *table; /* the hashtable itself with the buckets */ 41 spinlock_t *list_locks; /* spinlock for each hash list entry */ 42 int size; /* size of hashtable */ 43 }; 44 45 /* allocates and clears the hash */ 46 struct hashtable_t *hash_new(int size); 47 48 /* free only the hashtable and the hash itself. */ 49 void hash_destroy(struct hashtable_t *hash); 50 51 /* remove the hash structure. if hashdata_free_cb != NULL, this function will be 52 * called to remove the elements inside of the hash. if you don't remove the 53 * elements, memory might be leaked. */ 54 static inline void hash_delete(struct hashtable_t *hash, 55 hashdata_free_cb free_cb, void *arg) 56 { 57 struct hlist_head *head; 58 struct hlist_node *node, *node_tmp; 59 spinlock_t *list_lock; /* spinlock to protect write access */ 60 int i; 61 62 for (i = 0; i < hash->size; i++) { 63 head = &hash->table[i]; 64 list_lock = &hash->list_locks[i]; 65 66 spin_lock_bh(list_lock); 67 hlist_for_each_safe(node, node_tmp, head) { 68 hlist_del_rcu(node); 69 70 if (free_cb) 71 free_cb(node, arg); 72 } 73 spin_unlock_bh(list_lock); 74 } 75 76 hash_destroy(hash); 77 } 78 79 /** 80 * hash_add - adds data to the hashtable 81 * @hash: storage hash table 82 * @compare: callback to determine if 2 hash elements are identical 83 * @choose: callback calculating the hash index 84 * @data: data passed to the aforementioned callbacks as argument 85 * @data_node: to be added element 86 * 87 * Returns 0 on success, 1 if the element already is in the hash 88 * and -1 on error. 89 */ 90 91 static inline int hash_add(struct hashtable_t *hash, 92 hashdata_compare_cb compare, 93 hashdata_choose_cb choose, 94 const void *data, struct hlist_node *data_node) 95 { 96 int index, ret = -1; 97 struct hlist_head *head; 98 struct hlist_node *node; 99 spinlock_t *list_lock; /* spinlock to protect write access */ 100 101 if (!hash) 102 goto out; 103 104 index = choose(data, hash->size); 105 head = &hash->table[index]; 106 list_lock = &hash->list_locks[index]; 107 108 rcu_read_lock(); 109 __hlist_for_each_rcu(node, head) { 110 if (!compare(node, data)) 111 continue; 112 113 ret = 1; 114 goto err_unlock; 115 } 116 rcu_read_unlock(); 117 118 /* no duplicate found in list, add new element */ 119 spin_lock_bh(list_lock); 120 hlist_add_head_rcu(data_node, head); 121 spin_unlock_bh(list_lock); 122 123 ret = 0; 124 goto out; 125 126 err_unlock: 127 rcu_read_unlock(); 128 out: 129 return ret; 130 } 131 132 /* removes data from hash, if found. returns pointer do data on success, so you 133 * can remove the used structure yourself, or NULL on error . data could be the 134 * structure you use with just the key filled, we just need the key for 135 * comparing. */ 136 static inline void *hash_remove(struct hashtable_t *hash, 137 hashdata_compare_cb compare, 138 hashdata_choose_cb choose, void *data) 139 { 140 size_t index; 141 struct hlist_node *node; 142 struct hlist_head *head; 143 void *data_save = NULL; 144 145 index = choose(data, hash->size); 146 head = &hash->table[index]; 147 148 spin_lock_bh(&hash->list_locks[index]); 149 hlist_for_each(node, head) { 150 if (!compare(node, data)) 151 continue; 152 153 data_save = node; 154 hlist_del_rcu(node); 155 break; 156 } 157 spin_unlock_bh(&hash->list_locks[index]); 158 159 return data_save; 160 } 161 162 #endif /* _NET_BATMAN_ADV_HASH_H_ */ 163