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
  31 static 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  */
  64 static inline bool hash_hashed(struct hlist_node *node)
  65 {
  66         return !hlist_unhashed(node);
  67 }
  68
  69 static 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  */
  93 static 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