LXR linux/tools/include/linux/hashtable.h

   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
 150