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7e1e7763 TG |
1 | /* |
2 | * Resizable, Scalable, Concurrent Hash Table | |
3 | * | |
4 | * Copyright (c) 2014 Thomas Graf <tgraf@suug.ch> | |
5 | * Copyright (c) 2008-2014 Patrick McHardy <kaber@trash.net> | |
6 | * | |
7 | * Based on the following paper by Josh Triplett, Paul E. McKenney | |
8 | * and Jonathan Walpole: | |
9 | * https://www.usenix.org/legacy/event/atc11/tech/final_files/Triplett.pdf | |
10 | * | |
11 | * Code partially derived from nft_hash | |
12 | * | |
13 | * This program is free software; you can redistribute it and/or modify | |
14 | * it under the terms of the GNU General Public License version 2 as | |
15 | * published by the Free Software Foundation. | |
16 | */ | |
17 | ||
18 | #ifndef _LINUX_RHASHTABLE_H | |
19 | #define _LINUX_RHASHTABLE_H | |
20 | ||
21 | #include <linux/rculist.h> | |
22 | ||
23 | struct rhash_head { | |
5300fdcb | 24 | struct rhash_head __rcu *next; |
7e1e7763 TG |
25 | }; |
26 | ||
27 | #define INIT_HASH_HEAD(ptr) ((ptr)->next = NULL) | |
28 | ||
29 | struct bucket_table { | |
30 | size_t size; | |
31 | struct rhash_head __rcu *buckets[]; | |
32 | }; | |
33 | ||
34 | typedef u32 (*rht_hashfn_t)(const void *data, u32 len, u32 seed); | |
35 | typedef u32 (*rht_obj_hashfn_t)(const void *data, u32 seed); | |
36 | ||
37 | struct rhashtable; | |
38 | ||
39 | /** | |
40 | * struct rhashtable_params - Hash table construction parameters | |
41 | * @nelem_hint: Hint on number of elements, should be 75% of desired size | |
42 | * @key_len: Length of key | |
43 | * @key_offset: Offset of key in struct to be hashed | |
44 | * @head_offset: Offset of rhash_head in struct to be hashed | |
45 | * @hash_rnd: Seed to use while hashing | |
46 | * @max_shift: Maximum number of shifts while expanding | |
94000176 | 47 | * @min_shift: Minimum number of shifts while shrinking |
7e1e7763 TG |
48 | * @hashfn: Function to hash key |
49 | * @obj_hashfn: Function to hash object | |
50 | * @grow_decision: If defined, may return true if table should expand | |
51 | * @shrink_decision: If defined, may return true if table should shrink | |
52 | * @mutex_is_held: Must return true if protecting mutex is held | |
53 | */ | |
54 | struct rhashtable_params { | |
55 | size_t nelem_hint; | |
56 | size_t key_len; | |
57 | size_t key_offset; | |
58 | size_t head_offset; | |
59 | u32 hash_rnd; | |
60 | size_t max_shift; | |
94000176 | 61 | size_t min_shift; |
7e1e7763 TG |
62 | rht_hashfn_t hashfn; |
63 | rht_obj_hashfn_t obj_hashfn; | |
64 | bool (*grow_decision)(const struct rhashtable *ht, | |
65 | size_t new_size); | |
66 | bool (*shrink_decision)(const struct rhashtable *ht, | |
67 | size_t new_size); | |
68 | int (*mutex_is_held)(void); | |
69 | }; | |
70 | ||
71 | /** | |
72 | * struct rhashtable - Hash table handle | |
73 | * @tbl: Bucket table | |
74 | * @nelems: Number of elements in table | |
75 | * @shift: Current size (1 << shift) | |
76 | * @p: Configuration parameters | |
77 | */ | |
78 | struct rhashtable { | |
79 | struct bucket_table __rcu *tbl; | |
80 | size_t nelems; | |
81 | size_t shift; | |
82 | struct rhashtable_params p; | |
83 | }; | |
84 | ||
85 | #ifdef CONFIG_PROVE_LOCKING | |
86 | int lockdep_rht_mutex_is_held(const struct rhashtable *ht); | |
87 | #else | |
88 | static inline int lockdep_rht_mutex_is_held(const struct rhashtable *ht) | |
89 | { | |
90 | return 1; | |
91 | } | |
92 | #endif /* CONFIG_PROVE_LOCKING */ | |
93 | ||
94 | int rhashtable_init(struct rhashtable *ht, struct rhashtable_params *params); | |
95 | ||
96 | u32 rhashtable_hashfn(const struct rhashtable *ht, const void *key, u32 len); | |
97 | u32 rhashtable_obj_hashfn(const struct rhashtable *ht, void *ptr); | |
98 | ||
99 | void rhashtable_insert(struct rhashtable *ht, struct rhash_head *node, gfp_t); | |
100 | bool rhashtable_remove(struct rhashtable *ht, struct rhash_head *node, gfp_t); | |
101 | void rhashtable_remove_pprev(struct rhashtable *ht, struct rhash_head *obj, | |
5300fdcb | 102 | struct rhash_head __rcu **pprev, gfp_t flags); |
7e1e7763 TG |
103 | |
104 | bool rht_grow_above_75(const struct rhashtable *ht, size_t new_size); | |
105 | bool rht_shrink_below_30(const struct rhashtable *ht, size_t new_size); | |
106 | ||
107 | int rhashtable_expand(struct rhashtable *ht, gfp_t flags); | |
108 | int rhashtable_shrink(struct rhashtable *ht, gfp_t flags); | |
109 | ||
110 | void *rhashtable_lookup(const struct rhashtable *ht, const void *key); | |
111 | void *rhashtable_lookup_compare(const struct rhashtable *ht, u32 hash, | |
112 | bool (*compare)(void *, void *), void *arg); | |
113 | ||
114 | void rhashtable_destroy(const struct rhashtable *ht); | |
115 | ||
116 | #define rht_dereference(p, ht) \ | |
117 | rcu_dereference_protected(p, lockdep_rht_mutex_is_held(ht)) | |
118 | ||
119 | #define rht_dereference_rcu(p, ht) \ | |
120 | rcu_dereference_check(p, lockdep_rht_mutex_is_held(ht)) | |
121 | ||
7e1e7763 TG |
122 | #define rht_entry(ptr, type, member) container_of(ptr, type, member) |
123 | #define rht_entry_safe(ptr, type, member) \ | |
124 | ({ \ | |
125 | typeof(ptr) __ptr = (ptr); \ | |
126 | __ptr ? rht_entry(__ptr, type, member) : NULL; \ | |
127 | }) | |
7e1e7763 TG |
128 | |
129 | #define rht_next_entry_safe(pos, ht, member) \ | |
130 | ({ \ | |
131 | pos ? rht_entry_safe(rht_dereference((pos)->member.next, ht), \ | |
132 | typeof(*(pos)), member) : NULL; \ | |
133 | }) | |
134 | ||
135 | /** | |
136 | * rht_for_each - iterate over hash chain | |
137 | * @pos: &struct rhash_head to use as a loop cursor. | |
138 | * @head: head of the hash chain (struct rhash_head *) | |
139 | * @ht: pointer to your struct rhashtable | |
140 | */ | |
141 | #define rht_for_each(pos, head, ht) \ | |
142 | for (pos = rht_dereference(head, ht); \ | |
143 | pos; \ | |
144 | pos = rht_dereference((pos)->next, ht)) | |
145 | ||
146 | /** | |
147 | * rht_for_each_entry - iterate over hash chain of given type | |
148 | * @pos: type * to use as a loop cursor. | |
149 | * @head: head of the hash chain (struct rhash_head *) | |
150 | * @ht: pointer to your struct rhashtable | |
151 | * @member: name of the rhash_head within the hashable struct. | |
152 | */ | |
153 | #define rht_for_each_entry(pos, head, ht, member) \ | |
154 | for (pos = rht_entry_safe(rht_dereference(head, ht), \ | |
155 | typeof(*(pos)), member); \ | |
156 | pos; \ | |
157 | pos = rht_next_entry_safe(pos, ht, member)) | |
158 | ||
159 | /** | |
160 | * rht_for_each_entry_safe - safely iterate over hash chain of given type | |
161 | * @pos: type * to use as a loop cursor. | |
162 | * @n: type * to use for temporary next object storage | |
163 | * @head: head of the hash chain (struct rhash_head *) | |
164 | * @ht: pointer to your struct rhashtable | |
165 | * @member: name of the rhash_head within the hashable struct. | |
166 | * | |
167 | * This hash chain list-traversal primitive allows for the looped code to | |
168 | * remove the loop cursor from the list. | |
169 | */ | |
170 | #define rht_for_each_entry_safe(pos, n, head, ht, member) \ | |
171 | for (pos = rht_entry_safe(rht_dereference(head, ht), \ | |
172 | typeof(*(pos)), member), \ | |
173 | n = rht_next_entry_safe(pos, ht, member); \ | |
174 | pos; \ | |
175 | pos = n, \ | |
176 | n = rht_next_entry_safe(pos, ht, member)) | |
177 | ||
178 | /** | |
179 | * rht_for_each_rcu - iterate over rcu hash chain | |
180 | * @pos: &struct rhash_head to use as a loop cursor. | |
181 | * @head: head of the hash chain (struct rhash_head *) | |
182 | * @ht: pointer to your struct rhashtable | |
183 | * | |
184 | * This hash chain list-traversal primitive may safely run concurrently with | |
185 | * the _rcu fkht mutation primitives such as rht_insert() as long as the | |
186 | * traversal is guarded by rcu_read_lock(). | |
187 | */ | |
188 | #define rht_for_each_rcu(pos, head, ht) \ | |
189 | for (pos = rht_dereference_rcu(head, ht); \ | |
190 | pos; \ | |
191 | pos = rht_dereference_rcu((pos)->next, ht)) | |
192 | ||
193 | /** | |
194 | * rht_for_each_entry_rcu - iterate over rcu hash chain of given type | |
195 | * @pos: type * to use as a loop cursor. | |
196 | * @head: head of the hash chain (struct rhash_head *) | |
197 | * @member: name of the rhash_head within the hashable struct. | |
198 | * | |
199 | * This hash chain list-traversal primitive may safely run concurrently with | |
200 | * the _rcu fkht mutation primitives such as rht_insert() as long as the | |
201 | * traversal is guarded by rcu_read_lock(). | |
202 | */ | |
203 | #define rht_for_each_entry_rcu(pos, head, member) \ | |
93f56081 TG |
204 | for (pos = rht_entry_safe(rcu_dereference_raw(head), \ |
205 | typeof(*(pos)), member); \ | |
7e1e7763 | 206 | pos; \ |
93f56081 TG |
207 | pos = rht_entry_safe(rcu_dereference_raw((pos)->member.next), \ |
208 | typeof(*(pos)), member)) | |
7e1e7763 TG |
209 | |
210 | #endif /* _LINUX_RHASHTABLE_H */ |