1 /*
2 * Statically sized hash table implementation
3 * (C) 2012 Sasha Levin <levinsasha928@gmail.com>
4 */
5
6 #ifndef _LINUX_HASHTABLE_H
7 #define _LINUX_HASHTABLE_H
8
9 #include <linux/list.h>
10 #include <linux/types.h>
11 #include <linux/kernel.h>
12 #include <linux/hash.h>
13 #include <linux/rculist.h>
14
15 #define DEFINE_HASHTABLE(name, bits) \
16 struct hlist_head name[1 << (bits)] = \
17 { [0 ... ((1 << (bits)) - 1)] = HLIST_HEAD_INIT }
18
19 #define DECLARE_HASHTABLE(name, bits) \
20 struct hlist_head name[1 << (bits)]
21
22 #define HASH_SIZE(name) (ARRAY_SIZE(name))
23 #define HASH_BITS(name) ilog2(HASH_SIZE(name))
24
25 /* Use hash_32 when possible to allow for fast 32bit hashing in 64bit kernels. */
26 #define hash_min(val, bits) \
27 (sizeof(val) <= 4 ? hash_32(val, bits) : hash_long(val, bits))
28
__hash_init(struct hlist_head * ht,unsigned int sz)29 static inline void __hash_init(struct hlist_head *ht, unsigned int sz)
30 {
31 unsigned int i;
32
33 for (i = 0; i < sz; i++)
34 INIT_HLIST_HEAD(&ht[i]);
35 }
36
37 /**
38 * hash_init - initialize a hash table
39 * @hashtable: hashtable to be initialized
40 *
41 * Calculates the size of the hashtable from the given parameter, otherwise
42 * same as hash_init_size.
43 *
44 * This has to be a macro since HASH_BITS() will not work on pointers since
45 * it calculates the size during preprocessing.
46 */
47 #define hash_init(hashtable) __hash_init(hashtable, HASH_SIZE(hashtable))
48
49 /**
50 * hash_add - add an object to a hashtable
51 * @hashtable: hashtable to add to
52 * @node: the &struct hlist_node of the object to be added
53 * @key: the key of the object to be added
54 */
55 #define hash_add(hashtable, node, key) \
56 hlist_add_head(node, &hashtable[hash_min(key, HASH_BITS(hashtable))])
57
58 /**
59 * hash_add_rcu - add an object to a rcu enabled hashtable
60 * @hashtable: hashtable to add to
61 * @node: the &struct hlist_node of the object to be added
62 * @key: the key of the object to be added
63 */
64 #define hash_add_rcu(hashtable, node, key) \
65 hlist_add_head_rcu(node, &hashtable[hash_min(key, HASH_BITS(hashtable))])
66
67 /**
68 * hash_hashed - check whether an object is in any hashtable
69 * @node: the &struct hlist_node of the object to be checked
70 */
hash_hashed(struct hlist_node * node)71 static inline bool hash_hashed(struct hlist_node *node)
72 {
73 return !hlist_unhashed(node);
74 }
75
__hash_empty(struct hlist_head * ht,unsigned int sz)76 static inline bool __hash_empty(struct hlist_head *ht, unsigned int sz)
77 {
78 unsigned int i;
79
80 for (i = 0; i < sz; i++)
81 if (!hlist_empty(&ht[i]))
82 return false;
83
84 return true;
85 }
86
87 /**
88 * hash_empty - check whether a hashtable is empty
89 * @hashtable: hashtable to check
90 *
91 * This has to be a macro since HASH_BITS() will not work on pointers since
92 * it calculates the size during preprocessing.
93 */
94 #define hash_empty(hashtable) __hash_empty(hashtable, HASH_SIZE(hashtable))
95
96 /**
97 * hash_del - remove an object from a hashtable
98 * @node: &struct hlist_node of the object to remove
99 */
hash_del(struct hlist_node * node)100 static inline void hash_del(struct hlist_node *node)
101 {
102 hlist_del_init(node);
103 }
104
105 /**
106 * hash_del_rcu - remove an object from a rcu enabled hashtable
107 * @node: &struct hlist_node of the object to remove
108 */
hash_del_rcu(struct hlist_node * node)109 static inline void hash_del_rcu(struct hlist_node *node)
110 {
111 hlist_del_init_rcu(node);
112 }
113
114 /**
115 * hash_for_each - iterate over a hashtable
116 * @name: hashtable to iterate
117 * @bkt: integer to use as bucket loop cursor
118 * @node: the &struct list_head to use as a loop cursor for each entry
119 * @obj: the type * to use as a loop cursor for each entry
120 * @member: the name of the hlist_node within the struct
121 */
122 #define hash_for_each(name, bkt, node, obj, member) \
123 for ((bkt) = 0, node = NULL; node == NULL && (bkt) < HASH_SIZE(name); (bkt)++)\
124 hlist_for_each_entry(obj, node, &name[bkt], member)
125
126 /**
127 * hash_for_each_rcu - iterate over a rcu enabled hashtable
128 * @name: hashtable to iterate
129 * @bkt: integer to use as bucket loop cursor
130 * @node: the &struct list_head to use as a loop cursor for each entry
131 * @obj: the type * to use as a loop cursor for each entry
132 * @member: the name of the hlist_node within the struct
133 */
134 #define hash_for_each_rcu(name, bkt, node, obj, member) \
135 for ((bkt) = 0, node = NULL; node == NULL && (bkt) < HASH_SIZE(name); (bkt)++)\
136 hlist_for_each_entry_rcu(obj, node, &name[bkt], member)
137
138 /**
139 * hash_for_each_safe - iterate over a hashtable safe against removal of
140 * hash entry
141 * @name: hashtable to iterate
142 * @bkt: integer to use as bucket loop cursor
143 * @node: the &struct list_head to use as a loop cursor for each entry
144 * @tmp: a &struct used for temporary storage
145 * @obj: the type * to use as a loop cursor for each entry
146 * @member: the name of the hlist_node within the struct
147 */
148 #define hash_for_each_safe(name, bkt, node, tmp, obj, member) \
149 for ((bkt) = 0, node = NULL; node == NULL && (bkt) < HASH_SIZE(name); (bkt)++)\
150 hlist_for_each_entry_safe(obj, node, tmp, &name[bkt], member)
151
152 /**
153 * hash_for_each_possible - iterate over all possible objects hashing to the
154 * same bucket
155 * @name: hashtable to iterate
156 * @obj: the type * to use as a loop cursor for each entry
157 * @node: the &struct list_head to use as a loop cursor for each entry
158 * @member: the name of the hlist_node within the struct
159 * @key: the key of the objects to iterate over
160 */
161 #define hash_for_each_possible(name, obj, node, member, key) \
162 hlist_for_each_entry(obj, node, &name[hash_min(key, HASH_BITS(name))], member)
163
164 /**
165 * hash_for_each_possible_rcu - iterate over all possible objects hashing to the
166 * same bucket in an rcu enabled hashtable
167 * in a rcu enabled hashtable
168 * @name: hashtable to iterate
169 * @obj: the type * to use as a loop cursor for each entry
170 * @node: the &struct list_head to use as a loop cursor for each entry
171 * @member: the name of the hlist_node within the struct
172 * @key: the key of the objects to iterate over
173 */
174 #define hash_for_each_possible_rcu(name, obj, node, member, key) \
175 hlist_for_each_entry_rcu(obj, node, &name[hash_min(key, HASH_BITS(name))], member)
176
177 /**
178 * hash_for_each_possible_safe - iterate over all possible objects hashing to the
179 * same bucket safe against removals
180 * @name: hashtable to iterate
181 * @obj: the type * to use as a loop cursor for each entry
182 * @node: the &struct list_head to use as a loop cursor for each entry
183 * @tmp: a &struct used for temporary storage
184 * @member: the name of the hlist_node within the struct
185 * @key: the key of the objects to iterate over
186 */
187 #define hash_for_each_possible_safe(name, obj, node, tmp, member, key) \
188 hlist_for_each_entry_safe(obj, node, tmp, \
189 &name[hash_min(key, HASH_BITS(name))], member)
190
191
192 #endif
193