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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> | |
97defe1e | 22 | #include <linux/workqueue.h> |
7e1e7763 TG |
23 | |
24 | struct rhash_head { | |
5300fdcb | 25 | struct rhash_head __rcu *next; |
7e1e7763 TG |
26 | }; |
27 | ||
28 | #define INIT_HASH_HEAD(ptr) ((ptr)->next = NULL) | |
29 | ||
97defe1e TG |
30 | /** |
31 | * struct bucket_table - Table of hash buckets | |
32 | * @size: Number of hash buckets | |
33 | * @locks_mask: Mask to apply before accessing locks[] | |
34 | * @locks: Array of spinlocks protecting individual buckets | |
35 | * @buckets: size * hash buckets | |
36 | */ | |
7e1e7763 TG |
37 | struct bucket_table { |
38 | size_t size; | |
97defe1e TG |
39 | unsigned int locks_mask; |
40 | spinlock_t *locks; | |
7e1e7763 TG |
41 | struct rhash_head __rcu *buckets[]; |
42 | }; | |
43 | ||
44 | typedef u32 (*rht_hashfn_t)(const void *data, u32 len, u32 seed); | |
45 | typedef u32 (*rht_obj_hashfn_t)(const void *data, u32 seed); | |
46 | ||
47 | struct rhashtable; | |
48 | ||
49 | /** | |
50 | * struct rhashtable_params - Hash table construction parameters | |
51 | * @nelem_hint: Hint on number of elements, should be 75% of desired size | |
52 | * @key_len: Length of key | |
53 | * @key_offset: Offset of key in struct to be hashed | |
54 | * @head_offset: Offset of rhash_head in struct to be hashed | |
55 | * @hash_rnd: Seed to use while hashing | |
56 | * @max_shift: Maximum number of shifts while expanding | |
94000176 | 57 | * @min_shift: Minimum number of shifts while shrinking |
97defe1e | 58 | * @locks_mul: Number of bucket locks to allocate per cpu (default: 128) |
7e1e7763 TG |
59 | * @hashfn: Function to hash key |
60 | * @obj_hashfn: Function to hash object | |
61 | * @grow_decision: If defined, may return true if table should expand | |
62 | * @shrink_decision: If defined, may return true if table should shrink | |
7e1e7763 TG |
63 | */ |
64 | struct rhashtable_params { | |
65 | size_t nelem_hint; | |
66 | size_t key_len; | |
67 | size_t key_offset; | |
68 | size_t head_offset; | |
69 | u32 hash_rnd; | |
70 | size_t max_shift; | |
94000176 | 71 | size_t min_shift; |
97defe1e | 72 | size_t locks_mul; |
7e1e7763 TG |
73 | rht_hashfn_t hashfn; |
74 | rht_obj_hashfn_t obj_hashfn; | |
75 | bool (*grow_decision)(const struct rhashtable *ht, | |
76 | size_t new_size); | |
77 | bool (*shrink_decision)(const struct rhashtable *ht, | |
78 | size_t new_size); | |
7e1e7763 TG |
79 | }; |
80 | ||
81 | /** | |
82 | * struct rhashtable - Hash table handle | |
83 | * @tbl: Bucket table | |
97defe1e | 84 | * @future_tbl: Table under construction during expansion/shrinking |
7e1e7763 TG |
85 | * @nelems: Number of elements in table |
86 | * @shift: Current size (1 << shift) | |
87 | * @p: Configuration parameters | |
97defe1e TG |
88 | * @run_work: Deferred worker to expand/shrink asynchronously |
89 | * @mutex: Mutex to protect current/future table swapping | |
90 | * @being_destroyed: True if table is set up for destruction | |
7e1e7763 TG |
91 | */ |
92 | struct rhashtable { | |
93 | struct bucket_table __rcu *tbl; | |
97defe1e TG |
94 | struct bucket_table __rcu *future_tbl; |
95 | atomic_t nelems; | |
7e1e7763 TG |
96 | size_t shift; |
97 | struct rhashtable_params p; | |
97defe1e TG |
98 | struct delayed_work run_work; |
99 | struct mutex mutex; | |
100 | bool being_destroyed; | |
7e1e7763 TG |
101 | }; |
102 | ||
103 | #ifdef CONFIG_PROVE_LOCKING | |
97defe1e | 104 | int lockdep_rht_mutex_is_held(struct rhashtable *ht); |
88d6ed15 | 105 | int lockdep_rht_bucket_is_held(const struct bucket_table *tbl, u32 hash); |
7e1e7763 | 106 | #else |
97defe1e | 107 | static inline int lockdep_rht_mutex_is_held(struct rhashtable *ht) |
7e1e7763 TG |
108 | { |
109 | return 1; | |
110 | } | |
88d6ed15 TG |
111 | |
112 | static inline int lockdep_rht_bucket_is_held(const struct bucket_table *tbl, | |
113 | u32 hash) | |
114 | { | |
115 | return 1; | |
116 | } | |
7e1e7763 TG |
117 | #endif /* CONFIG_PROVE_LOCKING */ |
118 | ||
119 | int rhashtable_init(struct rhashtable *ht, struct rhashtable_params *params); | |
120 | ||
6eba8224 TG |
121 | void rhashtable_insert(struct rhashtable *ht, struct rhash_head *node); |
122 | bool rhashtable_remove(struct rhashtable *ht, struct rhash_head *node); | |
7e1e7763 TG |
123 | |
124 | bool rht_grow_above_75(const struct rhashtable *ht, size_t new_size); | |
125 | bool rht_shrink_below_30(const struct rhashtable *ht, size_t new_size); | |
126 | ||
6eba8224 TG |
127 | int rhashtable_expand(struct rhashtable *ht); |
128 | int rhashtable_shrink(struct rhashtable *ht); | |
7e1e7763 | 129 | |
97defe1e TG |
130 | void *rhashtable_lookup(struct rhashtable *ht, const void *key); |
131 | void *rhashtable_lookup_compare(struct rhashtable *ht, const void *key, | |
7e1e7763 TG |
132 | bool (*compare)(void *, void *), void *arg); |
133 | ||
97defe1e | 134 | void rhashtable_destroy(struct rhashtable *ht); |
7e1e7763 TG |
135 | |
136 | #define rht_dereference(p, ht) \ | |
137 | rcu_dereference_protected(p, lockdep_rht_mutex_is_held(ht)) | |
138 | ||
139 | #define rht_dereference_rcu(p, ht) \ | |
140 | rcu_dereference_check(p, lockdep_rht_mutex_is_held(ht)) | |
141 | ||
88d6ed15 TG |
142 | #define rht_dereference_bucket(p, tbl, hash) \ |
143 | rcu_dereference_protected(p, lockdep_rht_bucket_is_held(tbl, hash)) | |
7e1e7763 | 144 | |
88d6ed15 TG |
145 | #define rht_dereference_bucket_rcu(p, tbl, hash) \ |
146 | rcu_dereference_check(p, lockdep_rht_bucket_is_held(tbl, hash)) | |
147 | ||
148 | #define rht_entry(tpos, pos, member) \ | |
149 | ({ tpos = container_of(pos, typeof(*tpos), member); 1; }) | |
7e1e7763 TG |
150 | |
151 | /** | |
88d6ed15 TG |
152 | * rht_for_each_continue - continue iterating over hash chain |
153 | * @pos: the &struct rhash_head to use as a loop cursor. | |
154 | * @head: the previous &struct rhash_head to continue from | |
155 | * @tbl: the &struct bucket_table | |
156 | * @hash: the hash value / bucket index | |
7e1e7763 | 157 | */ |
88d6ed15 TG |
158 | #define rht_for_each_continue(pos, head, tbl, hash) \ |
159 | for (pos = rht_dereference_bucket(head, tbl, hash); \ | |
7e1e7763 | 160 | pos; \ |
88d6ed15 TG |
161 | pos = rht_dereference_bucket((pos)->next, tbl, hash)) |
162 | ||
163 | /** | |
164 | * rht_for_each - iterate over hash chain | |
165 | * @pos: the &struct rhash_head to use as a loop cursor. | |
166 | * @tbl: the &struct bucket_table | |
167 | * @hash: the hash value / bucket index | |
168 | */ | |
169 | #define rht_for_each(pos, tbl, hash) \ | |
170 | rht_for_each_continue(pos, (tbl)->buckets[hash], tbl, hash) | |
171 | ||
172 | /** | |
173 | * rht_for_each_entry_continue - continue iterating over hash chain | |
174 | * @tpos: the type * to use as a loop cursor. | |
175 | * @pos: the &struct rhash_head to use as a loop cursor. | |
176 | * @head: the previous &struct rhash_head to continue from | |
177 | * @tbl: the &struct bucket_table | |
178 | * @hash: the hash value / bucket index | |
179 | * @member: name of the &struct rhash_head within the hashable struct. | |
180 | */ | |
181 | #define rht_for_each_entry_continue(tpos, pos, head, tbl, hash, member) \ | |
182 | for (pos = rht_dereference_bucket(head, tbl, hash); \ | |
183 | pos && rht_entry(tpos, pos, member); \ | |
184 | pos = rht_dereference_bucket((pos)->next, tbl, hash)) | |
7e1e7763 TG |
185 | |
186 | /** | |
187 | * rht_for_each_entry - iterate over hash chain of given type | |
88d6ed15 TG |
188 | * @tpos: the type * to use as a loop cursor. |
189 | * @pos: the &struct rhash_head to use as a loop cursor. | |
190 | * @tbl: the &struct bucket_table | |
191 | * @hash: the hash value / bucket index | |
192 | * @member: name of the &struct rhash_head within the hashable struct. | |
7e1e7763 | 193 | */ |
88d6ed15 TG |
194 | #define rht_for_each_entry(tpos, pos, tbl, hash, member) \ |
195 | rht_for_each_entry_continue(tpos, pos, (tbl)->buckets[hash], \ | |
196 | tbl, hash, member) | |
7e1e7763 TG |
197 | |
198 | /** | |
199 | * rht_for_each_entry_safe - safely iterate over hash chain of given type | |
88d6ed15 TG |
200 | * @tpos: the type * to use as a loop cursor. |
201 | * @pos: the &struct rhash_head to use as a loop cursor. | |
202 | * @next: the &struct rhash_head to use as next in loop cursor. | |
203 | * @tbl: the &struct bucket_table | |
204 | * @hash: the hash value / bucket index | |
205 | * @member: name of the &struct rhash_head within the hashable struct. | |
7e1e7763 TG |
206 | * |
207 | * This hash chain list-traversal primitive allows for the looped code to | |
208 | * remove the loop cursor from the list. | |
209 | */ | |
88d6ed15 TG |
210 | #define rht_for_each_entry_safe(tpos, pos, next, tbl, hash, member) \ |
211 | for (pos = rht_dereference_bucket((tbl)->buckets[hash], tbl, hash), \ | |
212 | next = pos ? rht_dereference_bucket(pos->next, tbl, hash) \ | |
213 | : NULL; \ | |
214 | pos && rht_entry(tpos, pos, member); \ | |
215 | pos = next) | |
216 | ||
217 | /** | |
218 | * rht_for_each_rcu_continue - continue iterating over rcu hash chain | |
219 | * @pos: the &struct rhash_head to use as a loop cursor. | |
220 | * @head: the previous &struct rhash_head to continue from | |
221 | * @tbl: the &struct bucket_table | |
222 | * @hash: the hash value / bucket index | |
223 | * | |
224 | * This hash chain list-traversal primitive may safely run concurrently with | |
225 | * the _rcu mutation primitives such as rhashtable_insert() as long as the | |
226 | * traversal is guarded by rcu_read_lock(). | |
227 | */ | |
228 | #define rht_for_each_rcu_continue(pos, head, tbl, hash) \ | |
229 | for (({barrier(); }), \ | |
230 | pos = rht_dereference_bucket_rcu(head, tbl, hash); \ | |
231 | pos; \ | |
232 | pos = rcu_dereference_raw(pos->next)) | |
7e1e7763 TG |
233 | |
234 | /** | |
235 | * rht_for_each_rcu - iterate over rcu hash chain | |
88d6ed15 TG |
236 | * @pos: the &struct rhash_head to use as a loop cursor. |
237 | * @tbl: the &struct bucket_table | |
238 | * @hash: the hash value / bucket index | |
7e1e7763 TG |
239 | * |
240 | * This hash chain list-traversal primitive may safely run concurrently with | |
88d6ed15 | 241 | * the _rcu mutation primitives such as rhashtable_insert() as long as the |
7e1e7763 TG |
242 | * traversal is guarded by rcu_read_lock(). |
243 | */ | |
88d6ed15 TG |
244 | #define rht_for_each_rcu(pos, tbl, hash) \ |
245 | rht_for_each_rcu_continue(pos, (tbl)->buckets[hash], tbl, hash) | |
246 | ||
247 | /** | |
248 | * rht_for_each_entry_rcu_continue - continue iterating over rcu hash chain | |
249 | * @tpos: the type * to use as a loop cursor. | |
250 | * @pos: the &struct rhash_head to use as a loop cursor. | |
251 | * @head: the previous &struct rhash_head to continue from | |
252 | * @tbl: the &struct bucket_table | |
253 | * @hash: the hash value / bucket index | |
254 | * @member: name of the &struct rhash_head within the hashable struct. | |
255 | * | |
256 | * This hash chain list-traversal primitive may safely run concurrently with | |
257 | * the _rcu mutation primitives such as rhashtable_insert() as long as the | |
258 | * traversal is guarded by rcu_read_lock(). | |
259 | */ | |
260 | #define rht_for_each_entry_rcu_continue(tpos, pos, head, tbl, hash, member) \ | |
261 | for (({barrier(); }), \ | |
262 | pos = rht_dereference_bucket_rcu(head, tbl, hash); \ | |
263 | pos && rht_entry(tpos, pos, member); \ | |
264 | pos = rht_dereference_bucket_rcu(pos->next, tbl, hash)) | |
7e1e7763 TG |
265 | |
266 | /** | |
267 | * rht_for_each_entry_rcu - iterate over rcu hash chain of given type | |
88d6ed15 TG |
268 | * @tpos: the type * to use as a loop cursor. |
269 | * @pos: the &struct rhash_head to use as a loop cursor. | |
270 | * @tbl: the &struct bucket_table | |
271 | * @hash: the hash value / bucket index | |
272 | * @member: name of the &struct rhash_head within the hashable struct. | |
7e1e7763 TG |
273 | * |
274 | * This hash chain list-traversal primitive may safely run concurrently with | |
88d6ed15 | 275 | * the _rcu mutation primitives such as rhashtable_insert() as long as the |
7e1e7763 TG |
276 | * traversal is guarded by rcu_read_lock(). |
277 | */ | |
88d6ed15 TG |
278 | #define rht_for_each_entry_rcu(tpos, pos, tbl, hash, member) \ |
279 | rht_for_each_entry_rcu_continue(tpos, pos, (tbl)->buckets[hash],\ | |
280 | tbl, hash, member) | |
7e1e7763 TG |
281 | |
282 | #endif /* _LINUX_RHASHTABLE_H */ |