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/hash.h>
  14 #include <linux/rculist.h>
  15
  16 #define DEFINE_HASHTABLE(name, bits)                                            \
  17         struct hlist_head name[1 << (bits)] =                                   \
  18                         { [0 ... ((1 << (bits)) - 1)] = HLIST_HEAD_INIT }
  19
  20 #define DEFINE_READ_MOSTLY_HASHTABLE(name, bits)                                \
  21         struct hlist_head name[1 << (bits)] __read_mostly =                     \
  22                         { [0 ... ((1 << (bits)) - 1)] = HLIST_HEAD_INIT }
  23
  24 #define DECLARE_HASHTABLE(name, bits)                                           \
  25         struct hlist_head name[1 << (bits)]
  26
  27 #define HASH_SIZE(name) (ARRAY_SIZE(name))
  28 #define HASH_BITS(name) ilog2(HASH_SIZE(name))
  29
  30 /* Use hash_32 when possible to allow for fast 32bit hashing in 64bit kernels. */
  31 #define hash_min(val, bits)                                                     \
  32         (sizeof(val) <= 4 ? hash_32(val, bits) : hash_long(val, bits))
  33
  34 static inline void __hash_init(struct hlist_head *ht, unsigned int sz)
  35 {
  36         unsigned int i;
  37
  38         for (i = 0; i < sz; i++)
  39                 INIT_HLIST_HEAD(&ht[i]);
  40 }
  41
  42 /**
  43  * hash_init - initialize a hash table
  44  * @hashtable: hashtable to be initialized
  45  *
  46  * Calculates the size of the hashtable from the given parameter, otherwise
  47  * same as hash_init_size.
  48  *
  49  * This has to be a macro since HASH_BITS() will not work on pointers since
  50  * it calculates the size during preprocessing.
  51  */
  52 #define hash_init(hashtable) __hash_init(hashtable, HASH_SIZE(hashtable))
  53
  54 /**
  55  * hash_add - add an object to a hashtable
  56  * @hashtable: hashtable to add to
  57  * @node: the &struct hlist_node of the object to be added
  58  * @key: the key of the object to be added
  59  */
  60 #define hash_add(hashtable, node, key)                                          \
  61         hlist_add_head(node, &hashtable[hash_min(key, HASH_BITS(hashtable))])
  62
  63 /**
  64  * hash_add_rcu - add an object to a rcu enabled hashtable
  65  * @hashtable: hashtable to add to
  66  * @node: the &struct hlist_node of the object to be added
  67  * @key: the key of the object to be added
  68  */
  69 #define hash_add_rcu(hashtable, node, key)                                      \
  70         hlist_add_head_rcu(node, &hashtable[hash_min(key, HASH_BITS(hashtable))])
  71
  72 /**
  73  * hash_hashed - check whether an object is in any hashtable
  74  * @node: the &struct hlist_node of the object to be checked
  75  */
  76 static inline bool hash_hashed(struct hlist_node *node)
  77 {
  78         return !hlist_unhashed(node);
  79 }
  80
  81 static inline bool __hash_empty(struct hlist_head *ht, unsigned int sz)
  82 {
  83         unsigned int i;
  84
  85         for (i = 0; i < sz; i++)
  86                 if (!hlist_empty(&ht[i]))
  87                         return false;
  88
  89         return true;
  90 }
  91
  92 /**
  93  * hash_empty - check whether a hashtable is empty
  94  * @hashtable: hashtable to check
  95  *
  96  * This has to be a macro since HASH_BITS() will not work on pointers since
  97  * it calculates the size during preprocessing.
  98  */
  99 #define hash_empty(hashtable) __hash_empty(hashtable, HASH_SIZE(hashtable))
 100
 101 /**
 102  * hash_del - remove an object from a hashtable
 103  * @node: &struct hlist_node of the object to remove
 104  */
 105 static inline void hash_del(struct hlist_node *node)
 106 {
 107         hlist_del_init(node);
 108 }
 109
 110 /**
 111  * hash_del_rcu - remove an object from a rcu enabled hashtable
 112  * @node: &struct hlist_node of the object to remove
 113  */
 114 static inline void hash_del_rcu(struct hlist_node *node)
 115 {
 116         hlist_del_init_rcu(node);
 117 }
 118
 119 /**
 120  * hash_for_each - iterate over a hashtable
 121  * @name: hashtable to iterate
 122  * @bkt: integer to use as bucket loop cursor
 123  * @obj: the type * to use as a loop cursor for each entry
 124  * @member: the name of the hlist_node within the struct
 125  */
 126 #define hash_for_each(name, bkt, obj, member)                           \
 127         for ((bkt) = 0, obj = NULL; obj == NULL && (bkt) < HASH_SIZE(name);\
 128                         (bkt)++)\
 129                 hlist_for_each_entry(obj, &name[bkt], member)
 130
 131 /**
 132  * hash_for_each_rcu - iterate over a rcu enabled hashtable
 133  * @name: hashtable to iterate
 134  * @bkt: integer to use as bucket loop cursor
 135  * @obj: the type * to use as a loop cursor for each entry
 136  * @member: the name of the hlist_node within the struct
 137  */
 138 #define hash_for_each_rcu(name, bkt, obj, member)                       \
 139         for ((bkt) = 0, obj = NULL; obj == NULL && (bkt) < HASH_SIZE(name);\
 140                         (bkt)++)\
 141                 hlist_for_each_entry_rcu(obj, &name[bkt], member)
 142
 143 /**
 144  * hash_for_each_safe - iterate over a hashtable safe against removal of
 145  * hash entry
 146  * @name: hashtable to iterate
 147  * @bkt: integer to use as bucket loop cursor
 148  * @tmp: a &struct used for temporary storage
 149  * @obj: the type * to use as a loop cursor for each entry
 150  * @member: the name of the hlist_node within the struct
 151  */
 152 #define hash_for_each_safe(name, bkt, tmp, obj, member)                 \
 153         for ((bkt) = 0, obj = NULL; obj == NULL && (bkt) < HASH_SIZE(name);\
 154                         (bkt)++)\
 155                 hlist_for_each_entry_safe(obj, tmp, &name[bkt], member)
 156
 157 /**
 158  * hash_for_each_possible - iterate over all possible objects hashing to the
 159  * same bucket
 160  * @name: hashtable to iterate
 161  * @obj: the type * to use as a loop cursor for each entry
 162  * @member: the name of the hlist_node within the struct
 163  * @key: the key of the objects to iterate over
 164  */
 165 #define hash_for_each_possible(name, obj, member, key)                  \
 166         hlist_for_each_entry(obj, &name[hash_min(key, HASH_BITS(name))], member)
 167
 168 /**
 169  * hash_for_each_possible_rcu - iterate over all possible objects hashing to the
 170  * same bucket in an rcu enabled hashtable
 171  * @name: hashtable to iterate
 172  * @obj: the type * to use as a loop cursor for each entry
 173  * @member: the name of the hlist_node within the struct
 174  * @key: the key of the objects to iterate over
 175  */
 176 #define hash_for_each_possible_rcu(name, obj, member, key)              \
 177         hlist_for_each_entry_rcu(obj, &name[hash_min(key, HASH_BITS(name))],\
 178                 member)
 179
 180 /**
 181  * hash_for_each_possible_rcu_notrace - iterate over all possible objects hashing
 182  * to the same bucket in an rcu enabled hashtable in a rcu enabled hashtable
 183  * @name: hashtable to iterate
 184  * @obj: the type * to use as a loop cursor for each entry
 185  * @member: the name of the hlist_node within the struct
 186  * @key: the key of the objects to iterate over
 187  *
 188  * This is the same as hash_for_each_possible_rcu() except that it does
 189  * not do any RCU debugging or tracing.
 190  */
 191 #define hash_for_each_possible_rcu_notrace(name, obj, member, key) \
 192         hlist_for_each_entry_rcu_notrace(obj, \
 193                 &name[hash_min(key, HASH_BITS(name))], member)
 194
 195 /**
 196  * hash_for_each_possible_safe - iterate over all possible objects hashing to the
 197  * same bucket safe against removals
 198  * @name: hashtable to iterate
 199  * @obj: the type * to use as a loop cursor for each entry
 200  * @tmp: a &struct used for temporary storage
 201  * @member: the name of the hlist_node within the struct
 202  * @key: the key of the objects to iterate over
 203  */
 204 #define hash_for_each_possible_safe(name, obj, tmp, member, key)        \
 205         hlist_for_each_entry_safe(obj, tmp,\
 206                 &name[hash_min(key, HASH_BITS(name))], member)
 207
 208
 209 #endif