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  
__hash_init(struct hlist_head * ht,unsigned int sz)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   */
hash_hashed(struct hlist_node * node)76  static inline bool hash_hashed(struct hlist_node *node)
77  {
78  	return !hlist_unhashed(node);
79  }
80  
__hash_empty(struct hlist_head * ht,unsigned int sz)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   */
hash_del(struct hlist_node * node)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   */
hash_del_rcu(struct hlist_node * node)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 hlist_node 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, cond...)	\
177  	hlist_for_each_entry_rcu(obj, &name[hash_min(key, HASH_BITS(name))],\
178  		member, ## cond)
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 hlist_node 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
210