xref: /linux/include/linux/hashtable.h (revision a8b7b2d0)
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