hashtable.h (4544B)
1/* SPDX-License-Identifier: GPL-2.0 */ 2/* 3 * Statically sized hash table implementation 4 * (C) 2012 Sasha Levin <levinsasha928@gmail.com> 5 */ 6 7#ifndef _LINUX_HASHTABLE_H 8#define _LINUX_HASHTABLE_H 9 10#include <linux/list.h> 11#include <linux/types.h> 12#include <linux/kernel.h> 13#include <linux/bitops.h> 14#include <linux/hash.h> 15#include <linux/log2.h> 16 17#define DEFINE_HASHTABLE(name, bits) \ 18 struct hlist_head name[1 << (bits)] = \ 19 { [0 ... ((1 << (bits)) - 1)] = HLIST_HEAD_INIT } 20 21#define DECLARE_HASHTABLE(name, bits) \ 22 struct hlist_head name[1 << (bits)] 23 24#define HASH_SIZE(name) (ARRAY_SIZE(name)) 25#define HASH_BITS(name) ilog2(HASH_SIZE(name)) 26 27/* Use hash_32 when possible to allow for fast 32bit hashing in 64bit kernels. */ 28#define hash_min(val, bits) \ 29 (sizeof(val) <= 4 ? hash_32(val, bits) : hash_long(val, bits)) 30 31static inline void __hash_init(struct hlist_head *ht, unsigned int sz) 32{ 33 unsigned int i; 34 35 for (i = 0; i < sz; i++) 36 INIT_HLIST_HEAD(&ht[i]); 37} 38 39/** 40 * hash_init - initialize a hash table 41 * @hashtable: hashtable to be initialized 42 * 43 * Calculates the size of the hashtable from the given parameter, otherwise 44 * same as hash_init_size. 45 * 46 * This has to be a macro since HASH_BITS() will not work on pointers since 47 * it calculates the size during preprocessing. 48 */ 49#define hash_init(hashtable) __hash_init(hashtable, HASH_SIZE(hashtable)) 50 51/** 52 * hash_add - add an object to a hashtable 53 * @hashtable: hashtable to add to 54 * @node: the &struct hlist_node of the object to be added 55 * @key: the key of the object to be added 56 */ 57#define hash_add(hashtable, node, key) \ 58 hlist_add_head(node, &hashtable[hash_min(key, HASH_BITS(hashtable))]) 59 60/** 61 * hash_hashed - check whether an object is in any hashtable 62 * @node: the &struct hlist_node of the object to be checked 63 */ 64static inline bool hash_hashed(struct hlist_node *node) 65{ 66 return !hlist_unhashed(node); 67} 68 69static inline bool __hash_empty(struct hlist_head *ht, unsigned int sz) 70{ 71 unsigned int i; 72 73 for (i = 0; i < sz; i++) 74 if (!hlist_empty(&ht[i])) 75 return false; 76 77 return true; 78} 79 80/** 81 * hash_empty - check whether a hashtable is empty 82 * @hashtable: hashtable to check 83 * 84 * This has to be a macro since HASH_BITS() will not work on pointers since 85 * it calculates the size during preprocessing. 86 */ 87#define hash_empty(hashtable) __hash_empty(hashtable, HASH_SIZE(hashtable)) 88 89/** 90 * hash_del - remove an object from a hashtable 91 * @node: &struct hlist_node of the object to remove 92 */ 93static inline void hash_del(struct hlist_node *node) 94{ 95 hlist_del_init(node); 96} 97 98/** 99 * hash_for_each - iterate over a hashtable 100 * @name: hashtable to iterate 101 * @bkt: integer to use as bucket loop cursor 102 * @obj: the type * to use as a loop cursor for each entry 103 * @member: the name of the hlist_node within the struct 104 */ 105#define hash_for_each(name, bkt, obj, member) \ 106 for ((bkt) = 0, obj = NULL; obj == NULL && (bkt) < HASH_SIZE(name);\ 107 (bkt)++)\ 108 hlist_for_each_entry(obj, &name[bkt], member) 109 110/** 111 * hash_for_each_safe - iterate over a hashtable safe against removal of 112 * hash entry 113 * @name: hashtable to iterate 114 * @bkt: integer to use as bucket loop cursor 115 * @tmp: a &struct used for temporary storage 116 * @obj: the type * to use as a loop cursor for each entry 117 * @member: the name of the hlist_node within the struct 118 */ 119#define hash_for_each_safe(name, bkt, tmp, obj, member) \ 120 for ((bkt) = 0, obj = NULL; obj == NULL && (bkt) < HASH_SIZE(name);\ 121 (bkt)++)\ 122 hlist_for_each_entry_safe(obj, tmp, &name[bkt], member) 123 124/** 125 * hash_for_each_possible - iterate over all possible objects hashing to the 126 * same bucket 127 * @name: hashtable to iterate 128 * @obj: the type * to use as a loop cursor for each entry 129 * @member: the name of the hlist_node within the struct 130 * @key: the key of the objects to iterate over 131 */ 132#define hash_for_each_possible(name, obj, member, key) \ 133 hlist_for_each_entry(obj, &name[hash_min(key, HASH_BITS(name))], member) 134 135/** 136 * hash_for_each_possible_safe - iterate over all possible objects hashing to the 137 * same bucket safe against removals 138 * @name: hashtable to iterate 139 * @obj: the type * to use as a loop cursor for each entry 140 * @tmp: a &struct used for temporary storage 141 * @member: the name of the hlist_node within the struct 142 * @key: the key of the objects to iterate over 143 */ 144#define hash_for_each_possible_safe(name, obj, tmp, member, key) \ 145 hlist_for_each_entry_safe(obj, tmp,\ 146 &name[hash_min(key, HASH_BITS(name))], member) 147 148 149#endif