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)(struct hlist_node *, 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)(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 /* adds data to the hashtable. returns 0 on success, -1 on error */ 80 static inline int hash_add(struct hashtable_t *hash, 81 hashdata_compare_cb compare, 82 hashdata_choose_cb choose, 83 void *data, struct hlist_node *data_node) 84 { 85 int index; 86 struct hlist_head *head; 87 struct hlist_node *node; 88 spinlock_t *list_lock; /* spinlock to protect write access */ 89 90 if (!hash) 91 goto err; 92 93 index = choose(data, hash->size); 94 head = &hash->table[index]; 95 list_lock = &hash->list_locks[index]; 96 97 rcu_read_lock(); 98 __hlist_for_each_rcu(node, head) { 99 if (!compare(node, data)) 100 continue; 101 102 goto err_unlock; 103 } 104 rcu_read_unlock(); 105 106 /* no duplicate found in list, add new element */ 107 spin_lock_bh(list_lock); 108 hlist_add_head_rcu(data_node, head); 109 spin_unlock_bh(list_lock); 110 111 return 0; 112 113 err_unlock: 114 rcu_read_unlock(); 115 err: 116 return -1; 117 } 118 119 /* removes data from hash, if found. returns pointer do data on success, so you 120 * can remove the used structure yourself, or NULL on error . data could be the 121 * structure you use with just the key filled, we just need the key for 122 * comparing. */ 123 static inline void *hash_remove(struct hashtable_t *hash, 124 hashdata_compare_cb compare, 125 hashdata_choose_cb choose, void *data) 126 { 127 size_t index; 128 struct hlist_node *node; 129 struct hlist_head *head; 130 void *data_save = NULL; 131 132 index = choose(data, hash->size); 133 head = &hash->table[index]; 134 135 spin_lock_bh(&hash->list_locks[index]); 136 hlist_for_each(node, head) { 137 if (!compare(node, data)) 138 continue; 139 140 data_save = node; 141 hlist_del_rcu(node); 142 break; 143 } 144 spin_unlock_bh(&hash->list_locks[index]); 145 146 return data_save; 147 } 148 149 #endif /* _NET_BATMAN_ADV_HASH_H_ */ 150