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       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                 :          3 :         for (i = 0; i < sz; i++)
      39                 :          3 :                 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