linux/include/linux/hashtable.h
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   1/*
   2 * Statically sized hash table implementation
   3 * (C) 2012  Sasha Levin <levinsasha928@gmail.com>
   4 */
   5
   6#ifndef _LINUX_HASHTABLE_H
   7#define _LINUX_HASHTABLE_H
   8
   9#include <linux/list.h>
  10#include <linux/types.h>
  11#include <linux/kernel.h>
  12#include <linux/hash.h>
  13#include <linux/rculist.h>
  14
  15#define DEFINE_HASHTABLE(name, bits)                                            \
  16        struct hlist_head name[1 << (bits)] =                                   \
  17                        { [0 ... ((1 << (bits)) - 1)] = HLIST_HEAD_INIT }
  18
  19#define DECLARE_HASHTABLE(name, bits)                                           \
  20        struct hlist_head name[1 << (bits)]
  21
  22#define HASH_SIZE(name) (ARRAY_SIZE(name))
  23#define HASH_BITS(name) ilog2(HASH_SIZE(name))
  24
  25/* Use hash_32 when possible to allow for fast 32bit hashing in 64bit kernels. */
  26#define hash_min(val, bits)                                                     \
  27        (sizeof(val) <= 4 ? hash_32(val, bits) : hash_long(val, bits))
  28
  29static inline void __hash_init(struct hlist_head *ht, unsigned int sz)
  30{
  31        unsigned int i;
  32
  33        for (i = 0; i < sz; i++)
  34                INIT_HLIST_HEAD(&ht[i]);
  35}
  36
  37/**
  38 * hash_init - initialize a hash table
  39 * @hashtable: hashtable to be initialized
  40 *
  41 * Calculates the size of the hashtable from the given parameter, otherwise
  42 * same as hash_init_size.
  43 *
  44 * This has to be a macro since HASH_BITS() will not work on pointers since
  45 * it calculates the size during preprocessing.
  46 */
  47#define hash_init(hashtable) __hash_init(hashtable, HASH_SIZE(hashtable))
  48
  49/**
  50 * hash_add - add an object to a hashtable
  51 * @hashtable: hashtable to add to
  52 * @node: the &struct hlist_node of the object to be added
  53 * @key: the key of the object to be added
  54 */
  55#define hash_add(hashtable, node, key)                                          \
  56        hlist_add_head(node, &hashtable[hash_min(key, HASH_BITS(hashtable))])
  57
  58/**
  59 * hash_add_rcu - add an object to a rcu enabled hashtable
  60 * @hashtable: hashtable to add to
  61 * @node: the &struct hlist_node of the object to be added
  62 * @key: the key of the object to be added
  63 */
  64#define hash_add_rcu(hashtable, node, key)                                      \
  65        hlist_add_head_rcu(node, &hashtable[hash_min(key, HASH_BITS(hashtable))])
  66
  67/**
  68 * hash_hashed - check whether an object is in any hashtable
  69 * @node: the &struct hlist_node of the object to be checked
  70 */
  71static inline bool hash_hashed(struct hlist_node *node)
  72{
  73        return !hlist_unhashed(node);
  74}
  75
  76static inline bool __hash_empty(struct hlist_head *ht, unsigned int sz)
  77{
  78        unsigned int i;
  79
  80        for (i = 0; i < sz; i++)
  81                if (!hlist_empty(&ht[i]))
  82                        return false;
  83
  84        return true;
  85}
  86
  87/**
  88 * hash_empty - check whether a hashtable is empty
  89 * @hashtable: hashtable to check
  90 *
  91 * This has to be a macro since HASH_BITS() will not work on pointers since
  92 * it calculates the size during preprocessing.
  93 */
  94#define hash_empty(hashtable) __hash_empty(hashtable, HASH_SIZE(hashtable))
  95
  96/**
  97 * hash_del - remove an object from a hashtable
  98 * @node: &struct hlist_node of the object to remove
  99 */
 100static inline void hash_del(struct hlist_node *node)
 101{
 102        hlist_del_init(node);
 103}
 104
 105/**
 106 * hash_del_rcu - remove an object from a rcu enabled hashtable
 107 * @node: &struct hlist_node of the object to remove
 108 */
 109static inline void hash_del_rcu(struct hlist_node *node)
 110{
 111        hlist_del_init_rcu(node);
 112}
 113
 114/**
 115 * hash_for_each - iterate over a hashtable
 116 * @name: hashtable to iterate
 117 * @bkt: integer to use as bucket loop cursor
 118 * @obj: the type * to use as a loop cursor for each entry
 119 * @member: the name of the hlist_node within the struct
 120 */
 121#define hash_for_each(name, bkt, obj, member)                           \
 122        for ((bkt) = 0, obj = NULL; obj == NULL && (bkt) < HASH_SIZE(name);\
 123                        (bkt)++)\
 124                hlist_for_each_entry(obj, &name[bkt], member)
 125
 126/**
 127 * hash_for_each_rcu - iterate over a rcu enabled hashtable
 128 * @name: hashtable to iterate
 129 * @bkt: integer to use as bucket loop cursor
 130 * @obj: the type * to use as a loop cursor for each entry
 131 * @member: the name of the hlist_node within the struct
 132 */
 133#define hash_for_each_rcu(name, bkt, obj, member)                       \
 134        for ((bkt) = 0, obj = NULL; obj == NULL && (bkt) < HASH_SIZE(name);\
 135                        (bkt)++)\
 136                hlist_for_each_entry_rcu(obj, &name[bkt], member)
 137
 138/**
 139 * hash_for_each_safe - iterate over a hashtable safe against removal of
 140 * hash entry
 141 * @name: hashtable to iterate
 142 * @bkt: integer to use as bucket loop cursor
 143 * @tmp: a &struct used for temporary storage
 144 * @obj: the type * to use as a loop cursor for each entry
 145 * @member: the name of the hlist_node within the struct
 146 */
 147#define hash_for_each_safe(name, bkt, tmp, obj, member)                 \
 148        for ((bkt) = 0, obj = NULL; obj == NULL && (bkt) < HASH_SIZE(name);\
 149                        (bkt)++)\
 150                hlist_for_each_entry_safe(obj, tmp, &name[bkt], member)
 151
 152/**
 153 * hash_for_each_possible - iterate over all possible objects hashing to the
 154 * same bucket
 155 * @name: hashtable to iterate
 156 * @obj: the type * to use as a loop cursor for each entry
 157 * @member: the name of the hlist_node within the struct
 158 * @key: the key of the objects to iterate over
 159 */
 160#define hash_for_each_possible(name, obj, member, key)                  \
 161        hlist_for_each_entry(obj, &name[hash_min(key, HASH_BITS(name))], member)
 162
 163/**
 164 * hash_for_each_possible_rcu - iterate over all possible objects hashing to the
 165 * same bucket in an rcu enabled hashtable
 166 * in a rcu enabled hashtable
 167 * @name: hashtable to iterate
 168 * @obj: the type * to use as a loop cursor for each entry
 169 * @member: the name of the hlist_node within the struct
 170 * @key: the key of the objects to iterate over
 171 */
 172#define hash_for_each_possible_rcu(name, obj, member, key)              \
 173        hlist_for_each_entry_rcu(obj, &name[hash_min(key, HASH_BITS(name))],\
 174                member)
 175
 176/**
 177 * hash_for_each_possible_safe - iterate over all possible objects hashing to the
 178 * same bucket safe against removals
 179 * @name: hashtable to iterate
 180 * @obj: the type * to use as a loop cursor for each entry
 181 * @tmp: a &struct used for temporary storage
 182 * @member: the name of the hlist_node within the struct
 183 * @key: the key of the objects to iterate over
 184 */
 185#define hash_for_each_possible_safe(name, obj, tmp, member, key)        \
 186        hlist_for_each_entry_safe(obj, tmp,\
 187                &name[hash_min(key, HASH_BITS(name))], member)
 188
 189
 190#endif
 191
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