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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 | ||
f89bd6f8 | 21 | #include <linux/list_nulls.h> |
97defe1e | 22 | #include <linux/workqueue.h> |
86b35b64 | 23 | #include <linux/mutex.h> |
7e1e7763 | 24 | |
f89bd6f8 TG |
25 | /* |
26 | * The end of the chain is marked with a special nulls marks which has | |
27 | * the following format: | |
28 | * | |
29 | * +-------+-----------------------------------------------------+-+ | |
30 | * | Base | Hash |1| | |
31 | * +-------+-----------------------------------------------------+-+ | |
32 | * | |
33 | * Base (4 bits) : Reserved to distinguish between multiple tables. | |
34 | * Specified via &struct rhashtable_params.nulls_base. | |
35 | * Hash (27 bits): Full hash (unmasked) of first element added to bucket | |
36 | * 1 (1 bit) : Nulls marker (always set) | |
37 | * | |
38 | * The remaining bits of the next pointer remain unused for now. | |
39 | */ | |
40 | #define RHT_BASE_BITS 4 | |
41 | #define RHT_HASH_BITS 27 | |
42 | #define RHT_BASE_SHIFT RHT_HASH_BITS | |
43 | ||
7e1e7763 | 44 | struct rhash_head { |
5300fdcb | 45 | struct rhash_head __rcu *next; |
7e1e7763 TG |
46 | }; |
47 | ||
97defe1e TG |
48 | /** |
49 | * struct bucket_table - Table of hash buckets | |
50 | * @size: Number of hash buckets | |
51 | * @locks_mask: Mask to apply before accessing locks[] | |
52 | * @locks: Array of spinlocks protecting individual buckets | |
53 | * @buckets: size * hash buckets | |
54 | */ | |
7e1e7763 TG |
55 | struct bucket_table { |
56 | size_t size; | |
97defe1e TG |
57 | unsigned int locks_mask; |
58 | spinlock_t *locks; | |
7e1e7763 TG |
59 | struct rhash_head __rcu *buckets[]; |
60 | }; | |
61 | ||
62 | typedef u32 (*rht_hashfn_t)(const void *data, u32 len, u32 seed); | |
63 | typedef u32 (*rht_obj_hashfn_t)(const void *data, u32 seed); | |
64 | ||
65 | struct rhashtable; | |
66 | ||
67 | /** | |
68 | * struct rhashtable_params - Hash table construction parameters | |
69 | * @nelem_hint: Hint on number of elements, should be 75% of desired size | |
70 | * @key_len: Length of key | |
71 | * @key_offset: Offset of key in struct to be hashed | |
72 | * @head_offset: Offset of rhash_head in struct to be hashed | |
73 | * @hash_rnd: Seed to use while hashing | |
74 | * @max_shift: Maximum number of shifts while expanding | |
94000176 | 75 | * @min_shift: Minimum number of shifts while shrinking |
f89bd6f8 | 76 | * @nulls_base: Base value to generate nulls marker |
97defe1e | 77 | * @locks_mul: Number of bucket locks to allocate per cpu (default: 128) |
7e1e7763 TG |
78 | * @hashfn: Function to hash key |
79 | * @obj_hashfn: Function to hash object | |
80 | * @grow_decision: If defined, may return true if table should expand | |
81 | * @shrink_decision: If defined, may return true if table should shrink | |
7e1e7763 TG |
82 | */ |
83 | struct rhashtable_params { | |
84 | size_t nelem_hint; | |
85 | size_t key_len; | |
86 | size_t key_offset; | |
87 | size_t head_offset; | |
88 | u32 hash_rnd; | |
89 | size_t max_shift; | |
94000176 | 90 | size_t min_shift; |
f89bd6f8 | 91 | u32 nulls_base; |
97defe1e | 92 | size_t locks_mul; |
7e1e7763 TG |
93 | rht_hashfn_t hashfn; |
94 | rht_obj_hashfn_t obj_hashfn; | |
95 | bool (*grow_decision)(const struct rhashtable *ht, | |
96 | size_t new_size); | |
97 | bool (*shrink_decision)(const struct rhashtable *ht, | |
98 | size_t new_size); | |
7e1e7763 TG |
99 | }; |
100 | ||
101 | /** | |
102 | * struct rhashtable - Hash table handle | |
103 | * @tbl: Bucket table | |
97defe1e | 104 | * @future_tbl: Table under construction during expansion/shrinking |
7e1e7763 TG |
105 | * @nelems: Number of elements in table |
106 | * @shift: Current size (1 << shift) | |
107 | * @p: Configuration parameters | |
97defe1e TG |
108 | * @run_work: Deferred worker to expand/shrink asynchronously |
109 | * @mutex: Mutex to protect current/future table swapping | |
110 | * @being_destroyed: True if table is set up for destruction | |
7e1e7763 TG |
111 | */ |
112 | struct rhashtable { | |
113 | struct bucket_table __rcu *tbl; | |
97defe1e TG |
114 | struct bucket_table __rcu *future_tbl; |
115 | atomic_t nelems; | |
c0c09bfd | 116 | atomic_t shift; |
7e1e7763 | 117 | struct rhashtable_params p; |
97defe1e TG |
118 | struct delayed_work run_work; |
119 | struct mutex mutex; | |
120 | bool being_destroyed; | |
7e1e7763 TG |
121 | }; |
122 | ||
f89bd6f8 TG |
123 | static inline unsigned long rht_marker(const struct rhashtable *ht, u32 hash) |
124 | { | |
125 | return NULLS_MARKER(ht->p.nulls_base + hash); | |
126 | } | |
127 | ||
128 | #define INIT_RHT_NULLS_HEAD(ptr, ht, hash) \ | |
129 | ((ptr) = (typeof(ptr)) rht_marker(ht, hash)) | |
130 | ||
131 | static inline bool rht_is_a_nulls(const struct rhash_head *ptr) | |
132 | { | |
133 | return ((unsigned long) ptr & 1); | |
134 | } | |
135 | ||
136 | static inline unsigned long rht_get_nulls_value(const struct rhash_head *ptr) | |
137 | { | |
138 | return ((unsigned long) ptr) >> 1; | |
139 | } | |
140 | ||
7e1e7763 | 141 | #ifdef CONFIG_PROVE_LOCKING |
97defe1e | 142 | int lockdep_rht_mutex_is_held(struct rhashtable *ht); |
88d6ed15 | 143 | int lockdep_rht_bucket_is_held(const struct bucket_table *tbl, u32 hash); |
7e1e7763 | 144 | #else |
97defe1e | 145 | static inline int lockdep_rht_mutex_is_held(struct rhashtable *ht) |
7e1e7763 TG |
146 | { |
147 | return 1; | |
148 | } | |
88d6ed15 TG |
149 | |
150 | static inline int lockdep_rht_bucket_is_held(const struct bucket_table *tbl, | |
151 | u32 hash) | |
152 | { | |
153 | return 1; | |
154 | } | |
7e1e7763 TG |
155 | #endif /* CONFIG_PROVE_LOCKING */ |
156 | ||
157 | int rhashtable_init(struct rhashtable *ht, struct rhashtable_params *params); | |
158 | ||
6eba8224 TG |
159 | void rhashtable_insert(struct rhashtable *ht, struct rhash_head *node); |
160 | bool rhashtable_remove(struct rhashtable *ht, struct rhash_head *node); | |
7e1e7763 TG |
161 | |
162 | bool rht_grow_above_75(const struct rhashtable *ht, size_t new_size); | |
163 | bool rht_shrink_below_30(const struct rhashtable *ht, size_t new_size); | |
164 | ||
6eba8224 TG |
165 | int rhashtable_expand(struct rhashtable *ht); |
166 | int rhashtable_shrink(struct rhashtable *ht); | |
7e1e7763 | 167 | |
97defe1e TG |
168 | void *rhashtable_lookup(struct rhashtable *ht, const void *key); |
169 | void *rhashtable_lookup_compare(struct rhashtable *ht, const void *key, | |
7e1e7763 | 170 | bool (*compare)(void *, void *), void *arg); |
db304854 | 171 | bool rhashtable_lookup_insert(struct rhashtable *ht, struct rhash_head *obj); |
7e1e7763 | 172 | |
97defe1e | 173 | void rhashtable_destroy(struct rhashtable *ht); |
7e1e7763 TG |
174 | |
175 | #define rht_dereference(p, ht) \ | |
176 | rcu_dereference_protected(p, lockdep_rht_mutex_is_held(ht)) | |
177 | ||
178 | #define rht_dereference_rcu(p, ht) \ | |
179 | rcu_dereference_check(p, lockdep_rht_mutex_is_held(ht)) | |
180 | ||
88d6ed15 TG |
181 | #define rht_dereference_bucket(p, tbl, hash) \ |
182 | rcu_dereference_protected(p, lockdep_rht_bucket_is_held(tbl, hash)) | |
7e1e7763 | 183 | |
88d6ed15 TG |
184 | #define rht_dereference_bucket_rcu(p, tbl, hash) \ |
185 | rcu_dereference_check(p, lockdep_rht_bucket_is_held(tbl, hash)) | |
186 | ||
187 | #define rht_entry(tpos, pos, member) \ | |
188 | ({ tpos = container_of(pos, typeof(*tpos), member); 1; }) | |
7e1e7763 TG |
189 | |
190 | /** | |
88d6ed15 TG |
191 | * rht_for_each_continue - continue iterating over hash chain |
192 | * @pos: the &struct rhash_head to use as a loop cursor. | |
193 | * @head: the previous &struct rhash_head to continue from | |
194 | * @tbl: the &struct bucket_table | |
195 | * @hash: the hash value / bucket index | |
7e1e7763 | 196 | */ |
88d6ed15 TG |
197 | #define rht_for_each_continue(pos, head, tbl, hash) \ |
198 | for (pos = rht_dereference_bucket(head, tbl, hash); \ | |
f89bd6f8 | 199 | !rht_is_a_nulls(pos); \ |
88d6ed15 TG |
200 | pos = rht_dereference_bucket((pos)->next, tbl, hash)) |
201 | ||
202 | /** | |
203 | * rht_for_each - iterate over hash chain | |
204 | * @pos: the &struct rhash_head to use as a loop cursor. | |
205 | * @tbl: the &struct bucket_table | |
206 | * @hash: the hash value / bucket index | |
207 | */ | |
208 | #define rht_for_each(pos, tbl, hash) \ | |
209 | rht_for_each_continue(pos, (tbl)->buckets[hash], tbl, hash) | |
210 | ||
211 | /** | |
212 | * rht_for_each_entry_continue - continue iterating over hash chain | |
213 | * @tpos: the type * to use as a loop cursor. | |
214 | * @pos: the &struct rhash_head to use as a loop cursor. | |
215 | * @head: the previous &struct rhash_head to continue from | |
216 | * @tbl: the &struct bucket_table | |
217 | * @hash: the hash value / bucket index | |
218 | * @member: name of the &struct rhash_head within the hashable struct. | |
219 | */ | |
220 | #define rht_for_each_entry_continue(tpos, pos, head, tbl, hash, member) \ | |
221 | for (pos = rht_dereference_bucket(head, tbl, hash); \ | |
f89bd6f8 | 222 | (!rht_is_a_nulls(pos)) && rht_entry(tpos, pos, member); \ |
88d6ed15 | 223 | pos = rht_dereference_bucket((pos)->next, tbl, hash)) |
7e1e7763 TG |
224 | |
225 | /** | |
226 | * rht_for_each_entry - iterate over hash chain of given type | |
88d6ed15 TG |
227 | * @tpos: the type * to use as a loop cursor. |
228 | * @pos: the &struct rhash_head to use as a loop cursor. | |
229 | * @tbl: the &struct bucket_table | |
230 | * @hash: the hash value / bucket index | |
231 | * @member: name of the &struct rhash_head within the hashable struct. | |
7e1e7763 | 232 | */ |
88d6ed15 TG |
233 | #define rht_for_each_entry(tpos, pos, tbl, hash, member) \ |
234 | rht_for_each_entry_continue(tpos, pos, (tbl)->buckets[hash], \ | |
235 | tbl, hash, member) | |
7e1e7763 TG |
236 | |
237 | /** | |
238 | * rht_for_each_entry_safe - safely iterate over hash chain of given type | |
88d6ed15 TG |
239 | * @tpos: the type * to use as a loop cursor. |
240 | * @pos: the &struct rhash_head to use as a loop cursor. | |
241 | * @next: the &struct rhash_head to use as next in loop cursor. | |
242 | * @tbl: the &struct bucket_table | |
243 | * @hash: the hash value / bucket index | |
244 | * @member: name of the &struct rhash_head within the hashable struct. | |
7e1e7763 TG |
245 | * |
246 | * This hash chain list-traversal primitive allows for the looped code to | |
247 | * remove the loop cursor from the list. | |
248 | */ | |
88d6ed15 TG |
249 | #define rht_for_each_entry_safe(tpos, pos, next, tbl, hash, member) \ |
250 | for (pos = rht_dereference_bucket((tbl)->buckets[hash], tbl, hash), \ | |
f89bd6f8 TG |
251 | next = !rht_is_a_nulls(pos) ? \ |
252 | rht_dereference_bucket(pos->next, tbl, hash) : NULL; \ | |
253 | (!rht_is_a_nulls(pos)) && rht_entry(tpos, pos, member); \ | |
88d6ed15 TG |
254 | pos = next) |
255 | ||
256 | /** | |
257 | * rht_for_each_rcu_continue - continue iterating over rcu hash chain | |
258 | * @pos: the &struct rhash_head to use as a loop cursor. | |
259 | * @head: the previous &struct rhash_head to continue from | |
260 | * @tbl: the &struct bucket_table | |
261 | * @hash: the hash value / bucket index | |
262 | * | |
263 | * This hash chain list-traversal primitive may safely run concurrently with | |
264 | * the _rcu mutation primitives such as rhashtable_insert() as long as the | |
265 | * traversal is guarded by rcu_read_lock(). | |
266 | */ | |
267 | #define rht_for_each_rcu_continue(pos, head, tbl, hash) \ | |
268 | for (({barrier(); }), \ | |
269 | pos = rht_dereference_bucket_rcu(head, tbl, hash); \ | |
f89bd6f8 | 270 | !rht_is_a_nulls(pos); \ |
88d6ed15 | 271 | pos = rcu_dereference_raw(pos->next)) |
7e1e7763 TG |
272 | |
273 | /** | |
274 | * rht_for_each_rcu - iterate over rcu hash chain | |
88d6ed15 TG |
275 | * @pos: the &struct rhash_head to use as a loop cursor. |
276 | * @tbl: the &struct bucket_table | |
277 | * @hash: the hash value / bucket index | |
7e1e7763 TG |
278 | * |
279 | * This hash chain list-traversal primitive may safely run concurrently with | |
88d6ed15 | 280 | * the _rcu mutation primitives such as rhashtable_insert() as long as the |
7e1e7763 TG |
281 | * traversal is guarded by rcu_read_lock(). |
282 | */ | |
88d6ed15 TG |
283 | #define rht_for_each_rcu(pos, tbl, hash) \ |
284 | rht_for_each_rcu_continue(pos, (tbl)->buckets[hash], tbl, hash) | |
285 | ||
286 | /** | |
287 | * rht_for_each_entry_rcu_continue - continue iterating over rcu hash chain | |
288 | * @tpos: the type * to use as a loop cursor. | |
289 | * @pos: the &struct rhash_head to use as a loop cursor. | |
290 | * @head: the previous &struct rhash_head to continue from | |
291 | * @tbl: the &struct bucket_table | |
292 | * @hash: the hash value / bucket index | |
293 | * @member: name of the &struct rhash_head within the hashable struct. | |
294 | * | |
295 | * This hash chain list-traversal primitive may safely run concurrently with | |
296 | * the _rcu mutation primitives such as rhashtable_insert() as long as the | |
297 | * traversal is guarded by rcu_read_lock(). | |
298 | */ | |
299 | #define rht_for_each_entry_rcu_continue(tpos, pos, head, tbl, hash, member) \ | |
300 | for (({barrier(); }), \ | |
301 | pos = rht_dereference_bucket_rcu(head, tbl, hash); \ | |
f89bd6f8 | 302 | (!rht_is_a_nulls(pos)) && rht_entry(tpos, pos, member); \ |
88d6ed15 | 303 | pos = rht_dereference_bucket_rcu(pos->next, tbl, hash)) |
7e1e7763 TG |
304 | |
305 | /** | |
306 | * rht_for_each_entry_rcu - iterate over rcu hash chain of given type | |
88d6ed15 TG |
307 | * @tpos: the type * to use as a loop cursor. |
308 | * @pos: the &struct rhash_head to use as a loop cursor. | |
309 | * @tbl: the &struct bucket_table | |
310 | * @hash: the hash value / bucket index | |
311 | * @member: name of the &struct rhash_head within the hashable struct. | |
7e1e7763 TG |
312 | * |
313 | * This hash chain list-traversal primitive may safely run concurrently with | |
88d6ed15 | 314 | * the _rcu mutation primitives such as rhashtable_insert() as long as the |
7e1e7763 TG |
315 | * traversal is guarded by rcu_read_lock(). |
316 | */ | |
88d6ed15 TG |
317 | #define rht_for_each_entry_rcu(tpos, pos, tbl, hash, member) \ |
318 | rht_for_each_entry_rcu_continue(tpos, pos, (tbl)->buckets[hash],\ | |
319 | tbl, hash, member) | |
7e1e7763 TG |
320 | |
321 | #endif /* _LINUX_RHASHTABLE_H */ |