1 /* SPDX-License-Identifier: GPL-2.0 */ 2 /* Copyright (C) 2006-2020 B.A.T.M.A.N. contributors: 3 * 4 * Simon Wunderlich, Marek Lindner 5 */ 6 7 #ifndef _NET_BATMAN_ADV_HASH_H_ 8 #define _NET_BATMAN_ADV_HASH_H_ 9 10 #include "main.h" 11 12 #include <linux/atomic.h> 13 #include <linux/compiler.h> 14 #include <linux/list.h> 15 #include <linux/lockdep.h> 16 #include <linux/rculist.h> 17 #include <linux/spinlock.h> 18 #include <linux/stddef.h> 19 #include <linux/types.h> 20 21 /* callback to a compare function. should compare 2 element datas for their 22 * keys 23 * 24 * Return: true if same and false if not same 25 */ 26 typedef bool (*batadv_hashdata_compare_cb)(const struct hlist_node *, 27 const void *); 28 29 /* the hashfunction 30 * 31 * Return: an index based on the key in the data of the first argument and the 32 * size the second 33 */ 34 typedef u32 (*batadv_hashdata_choose_cb)(const void *, u32); 35 typedef void (*batadv_hashdata_free_cb)(struct hlist_node *, void *); 36 37 /** 38 * struct batadv_hashtable - Wrapper of simple hlist based hashtable 39 */ 40 struct batadv_hashtable { 41 /** @table: the hashtable itself with the buckets */ 42 struct hlist_head *table; 43 44 /** @list_locks: spinlock for each hash list entry */ 45 spinlock_t *list_locks; 46 47 /** @size: size of hashtable */ 48 u32 size; 49 50 /** @generation: current (generation) sequence number */ 51 atomic_t generation; 52 }; 53 54 /* allocates and clears the hash */ 55 struct batadv_hashtable *batadv_hash_new(u32 size); 56 57 /* set class key for all locks */ 58 void batadv_hash_set_lock_class(struct batadv_hashtable *hash, 59 struct lock_class_key *key); 60 61 /* free only the hashtable and the hash itself. */ 62 void batadv_hash_destroy(struct batadv_hashtable *hash); 63 64 /** 65 * batadv_hash_add() - adds data to the hashtable 66 * @hash: storage hash table 67 * @compare: callback to determine if 2 hash elements are identical 68 * @choose: callback calculating the hash index 69 * @data: data passed to the aforementioned callbacks as argument 70 * @data_node: to be added element 71 * 72 * Return: 0 on success, 1 if the element already is in the hash 73 * and -1 on error. 74 */ 75 static inline int batadv_hash_add(struct batadv_hashtable *hash, 76 batadv_hashdata_compare_cb compare, 77 batadv_hashdata_choose_cb choose, 78 const void *data, 79 struct hlist_node *data_node) 80 { 81 u32 index; 82 int ret = -1; 83 struct hlist_head *head; 84 struct hlist_node *node; 85 spinlock_t *list_lock; /* spinlock to protect write access */ 86 87 if (!hash) 88 goto out; 89 90 index = choose(data, hash->size); 91 head = &hash->table[index]; 92 list_lock = &hash->list_locks[index]; 93 94 spin_lock_bh(list_lock); 95 96 hlist_for_each(node, head) { 97 if (!compare(node, data)) 98 continue; 99 100 ret = 1; 101 goto unlock; 102 } 103 104 /* no duplicate found in list, add new element */ 105 hlist_add_head_rcu(data_node, head); 106 atomic_inc(&hash->generation); 107 108 ret = 0; 109 110 unlock: 111 spin_unlock_bh(list_lock); 112 out: 113 return ret; 114 } 115 116 /** 117 * batadv_hash_remove() - Removes data from hash, if found 118 * @hash: hash table 119 * @compare: callback to determine if 2 hash elements are identical 120 * @choose: callback calculating the hash index 121 * @data: data passed to the aforementioned callbacks as argument 122 * 123 * ata could be the structure you use with just the key filled, we just need 124 * the key for comparing. 125 * 126 * Return: returns pointer do data on success, so you can remove the used 127 * structure yourself, or NULL on error 128 */ 129 static inline void *batadv_hash_remove(struct batadv_hashtable *hash, 130 batadv_hashdata_compare_cb compare, 131 batadv_hashdata_choose_cb choose, 132 void *data) 133 { 134 u32 index; 135 struct hlist_node *node; 136 struct hlist_head *head; 137 void *data_save = NULL; 138 139 index = choose(data, hash->size); 140 head = &hash->table[index]; 141 142 spin_lock_bh(&hash->list_locks[index]); 143 hlist_for_each(node, head) { 144 if (!compare(node, data)) 145 continue; 146 147 data_save = node; 148 hlist_del_rcu(node); 149 atomic_inc(&hash->generation); 150 break; 151 } 152 spin_unlock_bh(&hash->list_locks[index]); 153 154 return data_save; 155 } 156 157 #endif /* _NET_BATMAN_ADV_HASH_H_ */ 158