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0eb71a9d | 1 | /* SPDX-License-Identifier: GPL-2.0 */ |
7e1e7763 TG |
2 | /* |
3 | * Resizable, Scalable, Concurrent Hash Table | |
4 | * | |
ca26893f | 5 | * Copyright (c) 2015-2016 Herbert Xu <herbert@gondor.apana.org.au> |
b5e2c150 | 6 | * Copyright (c) 2014-2015 Thomas Graf <tgraf@suug.ch> |
7e1e7763 TG |
7 | * Copyright (c) 2008-2014 Patrick McHardy <kaber@trash.net> |
8 | * | |
7e1e7763 | 9 | * Code partially derived from nft_hash |
dc0ee268 HX |
10 | * Rewritten with rehash code from br_multicast plus single list |
11 | * pointer as suggested by Josh Triplett | |
7e1e7763 TG |
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 | ||
3cf92222 | 21 | #include <linux/err.h> |
6626af69 | 22 | #include <linux/errno.h> |
31ccde2d | 23 | #include <linux/jhash.h> |
f89bd6f8 | 24 | #include <linux/list_nulls.h> |
97defe1e | 25 | #include <linux/workqueue.h> |
b2d09103 | 26 | #include <linux/rculist.h> |
7e1e7763 | 27 | |
0eb71a9d | 28 | #include <linux/rhashtable-types.h> |
f89bd6f8 TG |
29 | /* |
30 | * The end of the chain is marked with a special nulls marks which has | |
9f9a7077 | 31 | * the least significant bit set. |
f89bd6f8 | 32 | */ |
02fd97c3 | 33 | |
5f8ddeab FW |
34 | /* Maximum chain length before rehash |
35 | * | |
36 | * The maximum (not average) chain length grows with the size of the hash | |
37 | * table, at a rate of (log N)/(log log N). | |
38 | * | |
39 | * The value of 16 is selected so that even if the hash table grew to | |
40 | * 2^32 you would not expect the maximum chain length to exceed it | |
41 | * unless we are under attack (or extremely unlucky). | |
42 | * | |
43 | * As this limit is only to detect attacks, we don't need to set it to a | |
44 | * lower value as you'd need the chain length to vastly exceed 16 to have | |
45 | * any real effect on the system. | |
46 | */ | |
47 | #define RHT_ELASTICITY 16u | |
48 | ||
97defe1e TG |
49 | /** |
50 | * struct bucket_table - Table of hash buckets | |
51 | * @size: Number of hash buckets | |
da20420f | 52 | * @nest: Number of bits of first-level nested table. |
63d512d0 | 53 | * @rehash: Current bucket being rehashed |
988dfbd7 | 54 | * @hash_rnd: Random seed to fold into hash |
97defe1e TG |
55 | * @locks_mask: Mask to apply before accessing locks[] |
56 | * @locks: Array of spinlocks protecting individual buckets | |
eddee5ba | 57 | * @walkers: List of active walkers |
9d901bc0 | 58 | * @rcu: RCU structure for freeing the table |
c4db8848 | 59 | * @future_tbl: Table under construction during rehashing |
da20420f | 60 | * @ntbl: Nested table used when out of memory. |
97defe1e TG |
61 | * @buckets: size * hash buckets |
62 | */ | |
7e1e7763 | 63 | struct bucket_table { |
63d512d0 | 64 | unsigned int size; |
da20420f | 65 | unsigned int nest; |
63d512d0 | 66 | unsigned int rehash; |
988dfbd7 | 67 | u32 hash_rnd; |
b9ebafbe ED |
68 | unsigned int locks_mask; |
69 | spinlock_t *locks; | |
eddee5ba | 70 | struct list_head walkers; |
9d901bc0 | 71 | struct rcu_head rcu; |
b9ebafbe | 72 | |
c4db8848 HX |
73 | struct bucket_table __rcu *future_tbl; |
74 | ||
da20420f | 75 | struct rhash_head __rcu *buckets[] ____cacheline_aligned_in_smp; |
7e1e7763 TG |
76 | }; |
77 | ||
9b4f64a2 | 78 | #define INIT_RHT_NULLS_HEAD(ptr) \ |
9f9a7077 | 79 | ((ptr) = (typeof(ptr)) NULLS_MARKER(0)) |
f89bd6f8 TG |
80 | |
81 | static inline bool rht_is_a_nulls(const struct rhash_head *ptr) | |
82 | { | |
83 | return ((unsigned long) ptr & 1); | |
84 | } | |
85 | ||
02fd97c3 HX |
86 | static inline void *rht_obj(const struct rhashtable *ht, |
87 | const struct rhash_head *he) | |
88 | { | |
89 | return (char *)he - ht->p.head_offset; | |
90 | } | |
91 | ||
92 | static inline unsigned int rht_bucket_index(const struct bucket_table *tbl, | |
93 | unsigned int hash) | |
94 | { | |
9f9a7077 | 95 | return hash & (tbl->size - 1); |
02fd97c3 HX |
96 | } |
97 | ||
2b860931 TH |
98 | static inline unsigned int rht_key_get_hash(struct rhashtable *ht, |
99 | const void *key, const struct rhashtable_params params, | |
100 | unsigned int hash_rnd) | |
02fd97c3 | 101 | { |
299e5c32 | 102 | unsigned int hash; |
de91b25c | 103 | |
31ccde2d HX |
104 | /* params must be equal to ht->p if it isn't constant. */ |
105 | if (!__builtin_constant_p(params.key_len)) | |
2b860931 | 106 | hash = ht->p.hashfn(key, ht->key_len, hash_rnd); |
31ccde2d | 107 | else if (params.key_len) { |
299e5c32 | 108 | unsigned int key_len = params.key_len; |
31ccde2d HX |
109 | |
110 | if (params.hashfn) | |
2b860931 | 111 | hash = params.hashfn(key, key_len, hash_rnd); |
31ccde2d | 112 | else if (key_len & (sizeof(u32) - 1)) |
2b860931 | 113 | hash = jhash(key, key_len, hash_rnd); |
31ccde2d | 114 | else |
2b860931 | 115 | hash = jhash2(key, key_len / sizeof(u32), hash_rnd); |
31ccde2d | 116 | } else { |
299e5c32 | 117 | unsigned int key_len = ht->p.key_len; |
31ccde2d HX |
118 | |
119 | if (params.hashfn) | |
2b860931 | 120 | hash = params.hashfn(key, key_len, hash_rnd); |
31ccde2d | 121 | else |
2b860931 | 122 | hash = jhash(key, key_len, hash_rnd); |
31ccde2d HX |
123 | } |
124 | ||
2b860931 TH |
125 | return hash; |
126 | } | |
127 | ||
128 | static inline unsigned int rht_key_hashfn( | |
129 | struct rhashtable *ht, const struct bucket_table *tbl, | |
130 | const void *key, const struct rhashtable_params params) | |
131 | { | |
132 | unsigned int hash = rht_key_get_hash(ht, key, params, tbl->hash_rnd); | |
133 | ||
31ccde2d | 134 | return rht_bucket_index(tbl, hash); |
02fd97c3 HX |
135 | } |
136 | ||
137 | static inline unsigned int rht_head_hashfn( | |
138 | struct rhashtable *ht, const struct bucket_table *tbl, | |
139 | const struct rhash_head *he, const struct rhashtable_params params) | |
140 | { | |
141 | const char *ptr = rht_obj(ht, he); | |
142 | ||
143 | return likely(params.obj_hashfn) ? | |
49f7b33e PM |
144 | rht_bucket_index(tbl, params.obj_hashfn(ptr, params.key_len ?: |
145 | ht->p.key_len, | |
146 | tbl->hash_rnd)) : | |
02fd97c3 HX |
147 | rht_key_hashfn(ht, tbl, ptr + params.key_offset, params); |
148 | } | |
149 | ||
150 | /** | |
151 | * rht_grow_above_75 - returns true if nelems > 0.75 * table-size | |
152 | * @ht: hash table | |
153 | * @tbl: current table | |
154 | */ | |
155 | static inline bool rht_grow_above_75(const struct rhashtable *ht, | |
156 | const struct bucket_table *tbl) | |
157 | { | |
158 | /* Expand table when exceeding 75% load */ | |
159 | return atomic_read(&ht->nelems) > (tbl->size / 4 * 3) && | |
160 | (!ht->p.max_size || tbl->size < ht->p.max_size); | |
161 | } | |
162 | ||
163 | /** | |
164 | * rht_shrink_below_30 - returns true if nelems < 0.3 * table-size | |
165 | * @ht: hash table | |
166 | * @tbl: current table | |
167 | */ | |
168 | static inline bool rht_shrink_below_30(const struct rhashtable *ht, | |
169 | const struct bucket_table *tbl) | |
170 | { | |
171 | /* Shrink table beneath 30% load */ | |
172 | return atomic_read(&ht->nelems) < (tbl->size * 3 / 10) && | |
173 | tbl->size > ht->p.min_size; | |
174 | } | |
175 | ||
ccd57b1b HX |
176 | /** |
177 | * rht_grow_above_100 - returns true if nelems > table-size | |
178 | * @ht: hash table | |
179 | * @tbl: current table | |
180 | */ | |
181 | static inline bool rht_grow_above_100(const struct rhashtable *ht, | |
182 | const struct bucket_table *tbl) | |
183 | { | |
1d8dc3d3 JB |
184 | return atomic_read(&ht->nelems) > tbl->size && |
185 | (!ht->p.max_size || tbl->size < ht->p.max_size); | |
ccd57b1b HX |
186 | } |
187 | ||
07ee0722 HX |
188 | /** |
189 | * rht_grow_above_max - returns true if table is above maximum | |
190 | * @ht: hash table | |
191 | * @tbl: current table | |
192 | */ | |
193 | static inline bool rht_grow_above_max(const struct rhashtable *ht, | |
194 | const struct bucket_table *tbl) | |
195 | { | |
6d684e54 | 196 | return atomic_read(&ht->nelems) >= ht->max_elems; |
07ee0722 HX |
197 | } |
198 | ||
02fd97c3 HX |
199 | /* The bucket lock is selected based on the hash and protects mutations |
200 | * on a group of hash buckets. | |
201 | * | |
202 | * A maximum of tbl->size/2 bucket locks is allocated. This ensures that | |
203 | * a single lock always covers both buckets which may both contains | |
204 | * entries which link to the same bucket of the old table during resizing. | |
205 | * This allows to simplify the locking as locking the bucket in both | |
206 | * tables during resize always guarantee protection. | |
207 | * | |
208 | * IMPORTANT: When holding the bucket lock of both the old and new table | |
209 | * during expansions and shrinking, the old bucket lock must always be | |
210 | * acquired first. | |
211 | */ | |
212 | static inline spinlock_t *rht_bucket_lock(const struct bucket_table *tbl, | |
213 | unsigned int hash) | |
214 | { | |
215 | return &tbl->locks[hash & tbl->locks_mask]; | |
216 | } | |
217 | ||
7e1e7763 | 218 | #ifdef CONFIG_PROVE_LOCKING |
97defe1e | 219 | int lockdep_rht_mutex_is_held(struct rhashtable *ht); |
88d6ed15 | 220 | int lockdep_rht_bucket_is_held(const struct bucket_table *tbl, u32 hash); |
7e1e7763 | 221 | #else |
97defe1e | 222 | static inline int lockdep_rht_mutex_is_held(struct rhashtable *ht) |
7e1e7763 TG |
223 | { |
224 | return 1; | |
225 | } | |
88d6ed15 TG |
226 | |
227 | static inline int lockdep_rht_bucket_is_held(const struct bucket_table *tbl, | |
228 | u32 hash) | |
229 | { | |
230 | return 1; | |
231 | } | |
7e1e7763 TG |
232 | #endif /* CONFIG_PROVE_LOCKING */ |
233 | ||
ca26893f HX |
234 | void *rhashtable_insert_slow(struct rhashtable *ht, const void *key, |
235 | struct rhash_head *obj); | |
7e1e7763 | 236 | |
246779dd HX |
237 | void rhashtable_walk_enter(struct rhashtable *ht, |
238 | struct rhashtable_iter *iter); | |
f2dba9c6 | 239 | void rhashtable_walk_exit(struct rhashtable_iter *iter); |
97a6ec4a TH |
240 | int rhashtable_walk_start_check(struct rhashtable_iter *iter) __acquires(RCU); |
241 | ||
242 | static inline void rhashtable_walk_start(struct rhashtable_iter *iter) | |
243 | { | |
244 | (void)rhashtable_walk_start_check(iter); | |
245 | } | |
246 | ||
f2dba9c6 | 247 | void *rhashtable_walk_next(struct rhashtable_iter *iter); |
2db54b47 | 248 | void *rhashtable_walk_peek(struct rhashtable_iter *iter); |
f2dba9c6 HX |
249 | void rhashtable_walk_stop(struct rhashtable_iter *iter) __releases(RCU); |
250 | ||
6b6f302c TG |
251 | void rhashtable_free_and_destroy(struct rhashtable *ht, |
252 | void (*free_fn)(void *ptr, void *arg), | |
253 | void *arg); | |
97defe1e | 254 | void rhashtable_destroy(struct rhashtable *ht); |
7e1e7763 | 255 | |
da20420f HX |
256 | struct rhash_head __rcu **rht_bucket_nested(const struct bucket_table *tbl, |
257 | unsigned int hash); | |
258 | struct rhash_head __rcu **rht_bucket_nested_insert(struct rhashtable *ht, | |
259 | struct bucket_table *tbl, | |
260 | unsigned int hash); | |
261 | ||
7e1e7763 TG |
262 | #define rht_dereference(p, ht) \ |
263 | rcu_dereference_protected(p, lockdep_rht_mutex_is_held(ht)) | |
264 | ||
265 | #define rht_dereference_rcu(p, ht) \ | |
266 | rcu_dereference_check(p, lockdep_rht_mutex_is_held(ht)) | |
267 | ||
88d6ed15 TG |
268 | #define rht_dereference_bucket(p, tbl, hash) \ |
269 | rcu_dereference_protected(p, lockdep_rht_bucket_is_held(tbl, hash)) | |
7e1e7763 | 270 | |
88d6ed15 TG |
271 | #define rht_dereference_bucket_rcu(p, tbl, hash) \ |
272 | rcu_dereference_check(p, lockdep_rht_bucket_is_held(tbl, hash)) | |
273 | ||
274 | #define rht_entry(tpos, pos, member) \ | |
275 | ({ tpos = container_of(pos, typeof(*tpos), member); 1; }) | |
7e1e7763 | 276 | |
da20420f HX |
277 | static inline struct rhash_head __rcu *const *rht_bucket( |
278 | const struct bucket_table *tbl, unsigned int hash) | |
279 | { | |
280 | return unlikely(tbl->nest) ? rht_bucket_nested(tbl, hash) : | |
281 | &tbl->buckets[hash]; | |
282 | } | |
283 | ||
284 | static inline struct rhash_head __rcu **rht_bucket_var( | |
285 | struct bucket_table *tbl, unsigned int hash) | |
286 | { | |
287 | return unlikely(tbl->nest) ? rht_bucket_nested(tbl, hash) : | |
288 | &tbl->buckets[hash]; | |
289 | } | |
290 | ||
291 | static inline struct rhash_head __rcu **rht_bucket_insert( | |
292 | struct rhashtable *ht, struct bucket_table *tbl, unsigned int hash) | |
293 | { | |
294 | return unlikely(tbl->nest) ? rht_bucket_nested_insert(ht, tbl, hash) : | |
295 | &tbl->buckets[hash]; | |
296 | } | |
297 | ||
7e1e7763 | 298 | /** |
88d6ed15 TG |
299 | * rht_for_each_continue - continue iterating over hash chain |
300 | * @pos: the &struct rhash_head to use as a loop cursor. | |
301 | * @head: the previous &struct rhash_head to continue from | |
302 | * @tbl: the &struct bucket_table | |
303 | * @hash: the hash value / bucket index | |
7e1e7763 | 304 | */ |
88d6ed15 TG |
305 | #define rht_for_each_continue(pos, head, tbl, hash) \ |
306 | for (pos = rht_dereference_bucket(head, tbl, hash); \ | |
f89bd6f8 | 307 | !rht_is_a_nulls(pos); \ |
88d6ed15 TG |
308 | pos = rht_dereference_bucket((pos)->next, tbl, hash)) |
309 | ||
310 | /** | |
311 | * rht_for_each - iterate over hash chain | |
312 | * @pos: the &struct rhash_head to use as a loop cursor. | |
313 | * @tbl: the &struct bucket_table | |
314 | * @hash: the hash value / bucket index | |
315 | */ | |
316 | #define rht_for_each(pos, tbl, hash) \ | |
da20420f | 317 | rht_for_each_continue(pos, *rht_bucket(tbl, hash), tbl, hash) |
88d6ed15 TG |
318 | |
319 | /** | |
320 | * rht_for_each_entry_continue - continue iterating over hash chain | |
321 | * @tpos: the type * to use as a loop cursor. | |
322 | * @pos: the &struct rhash_head to use as a loop cursor. | |
323 | * @head: the previous &struct rhash_head to continue from | |
324 | * @tbl: the &struct bucket_table | |
325 | * @hash: the hash value / bucket index | |
326 | * @member: name of the &struct rhash_head within the hashable struct. | |
327 | */ | |
328 | #define rht_for_each_entry_continue(tpos, pos, head, tbl, hash, member) \ | |
329 | for (pos = rht_dereference_bucket(head, tbl, hash); \ | |
f89bd6f8 | 330 | (!rht_is_a_nulls(pos)) && rht_entry(tpos, pos, member); \ |
88d6ed15 | 331 | pos = rht_dereference_bucket((pos)->next, tbl, hash)) |
7e1e7763 TG |
332 | |
333 | /** | |
334 | * rht_for_each_entry - iterate over hash chain of given type | |
88d6ed15 TG |
335 | * @tpos: the type * to use as a loop cursor. |
336 | * @pos: the &struct rhash_head to use as a loop cursor. | |
337 | * @tbl: the &struct bucket_table | |
338 | * @hash: the hash value / bucket index | |
339 | * @member: name of the &struct rhash_head within the hashable struct. | |
7e1e7763 | 340 | */ |
88d6ed15 | 341 | #define rht_for_each_entry(tpos, pos, tbl, hash, member) \ |
da20420f | 342 | rht_for_each_entry_continue(tpos, pos, *rht_bucket(tbl, hash), \ |
88d6ed15 | 343 | tbl, hash, member) |
7e1e7763 TG |
344 | |
345 | /** | |
346 | * rht_for_each_entry_safe - safely iterate over hash chain of given type | |
88d6ed15 TG |
347 | * @tpos: the type * to use as a loop cursor. |
348 | * @pos: the &struct rhash_head to use as a loop cursor. | |
349 | * @next: the &struct rhash_head to use as next in loop cursor. | |
350 | * @tbl: the &struct bucket_table | |
351 | * @hash: the hash value / bucket index | |
352 | * @member: name of the &struct rhash_head within the hashable struct. | |
7e1e7763 TG |
353 | * |
354 | * This hash chain list-traversal primitive allows for the looped code to | |
355 | * remove the loop cursor from the list. | |
356 | */ | |
da20420f HX |
357 | #define rht_for_each_entry_safe(tpos, pos, next, tbl, hash, member) \ |
358 | for (pos = rht_dereference_bucket(*rht_bucket(tbl, hash), tbl, hash), \ | |
359 | next = !rht_is_a_nulls(pos) ? \ | |
360 | rht_dereference_bucket(pos->next, tbl, hash) : NULL; \ | |
361 | (!rht_is_a_nulls(pos)) && rht_entry(tpos, pos, member); \ | |
362 | pos = next, \ | |
363 | next = !rht_is_a_nulls(pos) ? \ | |
607954b0 | 364 | rht_dereference_bucket(pos->next, tbl, hash) : NULL) |
88d6ed15 TG |
365 | |
366 | /** | |
367 | * rht_for_each_rcu_continue - continue iterating over rcu hash chain | |
368 | * @pos: the &struct rhash_head to use as a loop cursor. | |
369 | * @head: the previous &struct rhash_head to continue from | |
370 | * @tbl: the &struct bucket_table | |
371 | * @hash: the hash value / bucket index | |
372 | * | |
373 | * This hash chain list-traversal primitive may safely run concurrently with | |
374 | * the _rcu mutation primitives such as rhashtable_insert() as long as the | |
375 | * traversal is guarded by rcu_read_lock(). | |
376 | */ | |
377 | #define rht_for_each_rcu_continue(pos, head, tbl, hash) \ | |
378 | for (({barrier(); }), \ | |
379 | pos = rht_dereference_bucket_rcu(head, tbl, hash); \ | |
f89bd6f8 | 380 | !rht_is_a_nulls(pos); \ |
88d6ed15 | 381 | pos = rcu_dereference_raw(pos->next)) |
7e1e7763 TG |
382 | |
383 | /** | |
384 | * rht_for_each_rcu - iterate over rcu hash chain | |
88d6ed15 TG |
385 | * @pos: the &struct rhash_head to use as a loop cursor. |
386 | * @tbl: the &struct bucket_table | |
387 | * @hash: the hash value / bucket index | |
7e1e7763 TG |
388 | * |
389 | * This hash chain list-traversal primitive may safely run concurrently with | |
88d6ed15 | 390 | * the _rcu mutation primitives such as rhashtable_insert() as long as the |
7e1e7763 TG |
391 | * traversal is guarded by rcu_read_lock(). |
392 | */ | |
88d6ed15 | 393 | #define rht_for_each_rcu(pos, tbl, hash) \ |
da20420f | 394 | rht_for_each_rcu_continue(pos, *rht_bucket(tbl, hash), tbl, hash) |
88d6ed15 TG |
395 | |
396 | /** | |
397 | * rht_for_each_entry_rcu_continue - continue iterating over rcu hash chain | |
398 | * @tpos: the type * to use as a loop cursor. | |
399 | * @pos: the &struct rhash_head to use as a loop cursor. | |
400 | * @head: the previous &struct rhash_head to continue from | |
401 | * @tbl: the &struct bucket_table | |
402 | * @hash: the hash value / bucket index | |
403 | * @member: name of the &struct rhash_head within the hashable struct. | |
404 | * | |
405 | * This hash chain list-traversal primitive may safely run concurrently with | |
406 | * the _rcu mutation primitives such as rhashtable_insert() as long as the | |
407 | * traversal is guarded by rcu_read_lock(). | |
408 | */ | |
409 | #define rht_for_each_entry_rcu_continue(tpos, pos, head, tbl, hash, member) \ | |
410 | for (({barrier(); }), \ | |
411 | pos = rht_dereference_bucket_rcu(head, tbl, hash); \ | |
f89bd6f8 | 412 | (!rht_is_a_nulls(pos)) && rht_entry(tpos, pos, member); \ |
88d6ed15 | 413 | pos = rht_dereference_bucket_rcu(pos->next, tbl, hash)) |
7e1e7763 TG |
414 | |
415 | /** | |
416 | * rht_for_each_entry_rcu - iterate over rcu hash chain of given type | |
88d6ed15 TG |
417 | * @tpos: the type * to use as a loop cursor. |
418 | * @pos: the &struct rhash_head to use as a loop cursor. | |
419 | * @tbl: the &struct bucket_table | |
420 | * @hash: the hash value / bucket index | |
421 | * @member: name of the &struct rhash_head within the hashable struct. | |
7e1e7763 TG |
422 | * |
423 | * This hash chain list-traversal primitive may safely run concurrently with | |
88d6ed15 | 424 | * the _rcu mutation primitives such as rhashtable_insert() as long as the |
7e1e7763 TG |
425 | * traversal is guarded by rcu_read_lock(). |
426 | */ | |
da20420f HX |
427 | #define rht_for_each_entry_rcu(tpos, pos, tbl, hash, member) \ |
428 | rht_for_each_entry_rcu_continue(tpos, pos, *rht_bucket(tbl, hash), \ | |
88d6ed15 | 429 | tbl, hash, member) |
7e1e7763 | 430 | |
ca26893f HX |
431 | /** |
432 | * rhl_for_each_rcu - iterate over rcu hash table list | |
433 | * @pos: the &struct rlist_head to use as a loop cursor. | |
434 | * @list: the head of the list | |
435 | * | |
436 | * This hash chain list-traversal primitive should be used on the | |
437 | * list returned by rhltable_lookup. | |
438 | */ | |
439 | #define rhl_for_each_rcu(pos, list) \ | |
440 | for (pos = list; pos; pos = rcu_dereference_raw(pos->next)) | |
441 | ||
442 | /** | |
443 | * rhl_for_each_entry_rcu - iterate over rcu hash table list of given type | |
444 | * @tpos: the type * to use as a loop cursor. | |
445 | * @pos: the &struct rlist_head to use as a loop cursor. | |
446 | * @list: the head of the list | |
447 | * @member: name of the &struct rlist_head within the hashable struct. | |
448 | * | |
449 | * This hash chain list-traversal primitive should be used on the | |
450 | * list returned by rhltable_lookup. | |
451 | */ | |
452 | #define rhl_for_each_entry_rcu(tpos, pos, list, member) \ | |
453 | for (pos = list; pos && rht_entry(tpos, pos, member); \ | |
454 | pos = rcu_dereference_raw(pos->next)) | |
455 | ||
02fd97c3 HX |
456 | static inline int rhashtable_compare(struct rhashtable_compare_arg *arg, |
457 | const void *obj) | |
458 | { | |
459 | struct rhashtable *ht = arg->ht; | |
460 | const char *ptr = obj; | |
461 | ||
462 | return memcmp(ptr + ht->p.key_offset, arg->key, ht->p.key_len); | |
463 | } | |
464 | ||
ca26893f HX |
465 | /* Internal function, do not use. */ |
466 | static inline struct rhash_head *__rhashtable_lookup( | |
02fd97c3 HX |
467 | struct rhashtable *ht, const void *key, |
468 | const struct rhashtable_params params) | |
469 | { | |
470 | struct rhashtable_compare_arg arg = { | |
471 | .ht = ht, | |
472 | .key = key, | |
473 | }; | |
da20420f | 474 | struct bucket_table *tbl; |
02fd97c3 | 475 | struct rhash_head *he; |
299e5c32 | 476 | unsigned int hash; |
02fd97c3 | 477 | |
02fd97c3 HX |
478 | tbl = rht_dereference_rcu(ht->tbl, ht); |
479 | restart: | |
480 | hash = rht_key_hashfn(ht, tbl, key, params); | |
481 | rht_for_each_rcu(he, tbl, hash) { | |
482 | if (params.obj_cmpfn ? | |
483 | params.obj_cmpfn(&arg, rht_obj(ht, he)) : | |
484 | rhashtable_compare(&arg, rht_obj(ht, he))) | |
485 | continue; | |
ca26893f | 486 | return he; |
02fd97c3 HX |
487 | } |
488 | ||
489 | /* Ensure we see any new tables. */ | |
490 | smp_rmb(); | |
491 | ||
492 | tbl = rht_dereference_rcu(tbl->future_tbl, ht); | |
493 | if (unlikely(tbl)) | |
494 | goto restart; | |
02fd97c3 HX |
495 | |
496 | return NULL; | |
497 | } | |
498 | ||
ca26893f HX |
499 | /** |
500 | * rhashtable_lookup - search hash table | |
501 | * @ht: hash table | |
502 | * @key: the pointer to the key | |
503 | * @params: hash table parameters | |
504 | * | |
505 | * Computes the hash value for the key and traverses the bucket chain looking | |
506 | * for a entry with an identical key. The first matching entry is returned. | |
507 | * | |
508 | * This must only be called under the RCU read lock. | |
509 | * | |
510 | * Returns the first entry on which the compare function returned true. | |
511 | */ | |
512 | static inline void *rhashtable_lookup( | |
513 | struct rhashtable *ht, const void *key, | |
514 | const struct rhashtable_params params) | |
515 | { | |
516 | struct rhash_head *he = __rhashtable_lookup(ht, key, params); | |
517 | ||
518 | return he ? rht_obj(ht, he) : NULL; | |
519 | } | |
520 | ||
521 | /** | |
522 | * rhashtable_lookup_fast - search hash table, without RCU read lock | |
523 | * @ht: hash table | |
524 | * @key: the pointer to the key | |
525 | * @params: hash table parameters | |
526 | * | |
527 | * Computes the hash value for the key and traverses the bucket chain looking | |
528 | * for a entry with an identical key. The first matching entry is returned. | |
529 | * | |
530 | * Only use this function when you have other mechanisms guaranteeing | |
531 | * that the object won't go away after the RCU read lock is released. | |
532 | * | |
533 | * Returns the first entry on which the compare function returned true. | |
534 | */ | |
535 | static inline void *rhashtable_lookup_fast( | |
536 | struct rhashtable *ht, const void *key, | |
537 | const struct rhashtable_params params) | |
538 | { | |
539 | void *obj; | |
540 | ||
541 | rcu_read_lock(); | |
542 | obj = rhashtable_lookup(ht, key, params); | |
543 | rcu_read_unlock(); | |
544 | ||
545 | return obj; | |
546 | } | |
547 | ||
548 | /** | |
549 | * rhltable_lookup - search hash list table | |
550 | * @hlt: hash table | |
551 | * @key: the pointer to the key | |
552 | * @params: hash table parameters | |
553 | * | |
554 | * Computes the hash value for the key and traverses the bucket chain looking | |
555 | * for a entry with an identical key. All matching entries are returned | |
556 | * in a list. | |
557 | * | |
558 | * This must only be called under the RCU read lock. | |
559 | * | |
560 | * Returns the list of entries that match the given key. | |
561 | */ | |
562 | static inline struct rhlist_head *rhltable_lookup( | |
563 | struct rhltable *hlt, const void *key, | |
564 | const struct rhashtable_params params) | |
565 | { | |
566 | struct rhash_head *he = __rhashtable_lookup(&hlt->ht, key, params); | |
567 | ||
568 | return he ? container_of(he, struct rhlist_head, rhead) : NULL; | |
569 | } | |
570 | ||
5ca8cc5b PNA |
571 | /* Internal function, please use rhashtable_insert_fast() instead. This |
572 | * function returns the existing element already in hashes in there is a clash, | |
573 | * otherwise it returns an error via ERR_PTR(). | |
574 | */ | |
575 | static inline void *__rhashtable_insert_fast( | |
02fd97c3 | 576 | struct rhashtable *ht, const void *key, struct rhash_head *obj, |
ca26893f | 577 | const struct rhashtable_params params, bool rhlist) |
02fd97c3 HX |
578 | { |
579 | struct rhashtable_compare_arg arg = { | |
580 | .ht = ht, | |
581 | .key = key, | |
582 | }; | |
ca26893f HX |
583 | struct rhash_head __rcu **pprev; |
584 | struct bucket_table *tbl; | |
02fd97c3 HX |
585 | struct rhash_head *head; |
586 | spinlock_t *lock; | |
299e5c32 | 587 | unsigned int hash; |
ca26893f HX |
588 | int elasticity; |
589 | void *data; | |
02fd97c3 HX |
590 | |
591 | rcu_read_lock(); | |
592 | ||
593 | tbl = rht_dereference_rcu(ht->tbl, ht); | |
ca26893f HX |
594 | hash = rht_head_hashfn(ht, tbl, obj, params); |
595 | lock = rht_bucket_lock(tbl, hash); | |
596 | spin_lock_bh(lock); | |
02fd97c3 | 597 | |
c0690016 | 598 | if (unlikely(rcu_access_pointer(tbl->future_tbl))) { |
ca26893f | 599 | slow_path: |
b824478b | 600 | spin_unlock_bh(lock); |
ca26893f HX |
601 | rcu_read_unlock(); |
602 | return rhashtable_insert_slow(ht, key, obj); | |
b824478b HX |
603 | } |
604 | ||
5f8ddeab | 605 | elasticity = RHT_ELASTICITY; |
da20420f HX |
606 | pprev = rht_bucket_insert(ht, tbl, hash); |
607 | data = ERR_PTR(-ENOMEM); | |
608 | if (!pprev) | |
609 | goto out; | |
610 | ||
611 | rht_for_each_continue(head, *pprev, tbl, hash) { | |
ca26893f HX |
612 | struct rhlist_head *plist; |
613 | struct rhlist_head *list; | |
614 | ||
615 | elasticity--; | |
616 | if (!key || | |
617 | (params.obj_cmpfn ? | |
618 | params.obj_cmpfn(&arg, rht_obj(ht, head)) : | |
d3dcf8eb PB |
619 | rhashtable_compare(&arg, rht_obj(ht, head)))) { |
620 | pprev = &head->next; | |
ca26893f | 621 | continue; |
d3dcf8eb | 622 | } |
ca26893f HX |
623 | |
624 | data = rht_obj(ht, head); | |
3cf92222 | 625 | |
ca26893f HX |
626 | if (!rhlist) |
627 | goto out; | |
5ca8cc5b | 628 | |
02fd97c3 | 629 | |
ca26893f HX |
630 | list = container_of(obj, struct rhlist_head, rhead); |
631 | plist = container_of(head, struct rhlist_head, rhead); | |
07ee0722 | 632 | |
ca26893f HX |
633 | RCU_INIT_POINTER(list->next, plist); |
634 | head = rht_dereference_bucket(head->next, tbl, hash); | |
635 | RCU_INIT_POINTER(list->rhead.next, head); | |
636 | rcu_assign_pointer(*pprev, obj); | |
ccd57b1b | 637 | |
ca26893f | 638 | goto good; |
ccd57b1b | 639 | } |
02fd97c3 | 640 | |
ca26893f HX |
641 | if (elasticity <= 0) |
642 | goto slow_path; | |
643 | ||
644 | data = ERR_PTR(-E2BIG); | |
645 | if (unlikely(rht_grow_above_max(ht, tbl))) | |
646 | goto out; | |
647 | ||
648 | if (unlikely(rht_grow_above_100(ht, tbl))) | |
649 | goto slow_path; | |
02fd97c3 | 650 | |
da20420f | 651 | head = rht_dereference_bucket(*pprev, tbl, hash); |
02fd97c3 HX |
652 | |
653 | RCU_INIT_POINTER(obj->next, head); | |
ca26893f HX |
654 | if (rhlist) { |
655 | struct rhlist_head *list; | |
656 | ||
657 | list = container_of(obj, struct rhlist_head, rhead); | |
658 | RCU_INIT_POINTER(list->next, NULL); | |
659 | } | |
02fd97c3 | 660 | |
da20420f | 661 | rcu_assign_pointer(*pprev, obj); |
02fd97c3 HX |
662 | |
663 | atomic_inc(&ht->nelems); | |
664 | if (rht_grow_above_75(ht, tbl)) | |
665 | schedule_work(&ht->run_work); | |
666 | ||
ca26893f HX |
667 | good: |
668 | data = NULL; | |
669 | ||
02fd97c3 HX |
670 | out: |
671 | spin_unlock_bh(lock); | |
672 | rcu_read_unlock(); | |
673 | ||
ca26893f | 674 | return data; |
02fd97c3 HX |
675 | } |
676 | ||
677 | /** | |
678 | * rhashtable_insert_fast - insert object into hash table | |
679 | * @ht: hash table | |
680 | * @obj: pointer to hash head inside object | |
681 | * @params: hash table parameters | |
682 | * | |
683 | * Will take a per bucket spinlock to protect against mutual mutations | |
684 | * on the same bucket. Multiple insertions may occur in parallel unless | |
685 | * they map to the same bucket lock. | |
686 | * | |
687 | * It is safe to call this function from atomic context. | |
688 | * | |
0c6f69a5 N |
689 | * Will trigger an automatic deferred table resizing if residency in the |
690 | * table grows beyond 70%. | |
02fd97c3 HX |
691 | */ |
692 | static inline int rhashtable_insert_fast( | |
693 | struct rhashtable *ht, struct rhash_head *obj, | |
694 | const struct rhashtable_params params) | |
695 | { | |
5ca8cc5b PNA |
696 | void *ret; |
697 | ||
ca26893f | 698 | ret = __rhashtable_insert_fast(ht, NULL, obj, params, false); |
5ca8cc5b PNA |
699 | if (IS_ERR(ret)) |
700 | return PTR_ERR(ret); | |
701 | ||
702 | return ret == NULL ? 0 : -EEXIST; | |
02fd97c3 HX |
703 | } |
704 | ||
ca26893f HX |
705 | /** |
706 | * rhltable_insert_key - insert object into hash list table | |
707 | * @hlt: hash list table | |
708 | * @key: the pointer to the key | |
709 | * @list: pointer to hash list head inside object | |
710 | * @params: hash table parameters | |
711 | * | |
712 | * Will take a per bucket spinlock to protect against mutual mutations | |
713 | * on the same bucket. Multiple insertions may occur in parallel unless | |
714 | * they map to the same bucket lock. | |
715 | * | |
716 | * It is safe to call this function from atomic context. | |
717 | * | |
0c6f69a5 N |
718 | * Will trigger an automatic deferred table resizing if residency in the |
719 | * table grows beyond 70%. | |
ca26893f HX |
720 | */ |
721 | static inline int rhltable_insert_key( | |
722 | struct rhltable *hlt, const void *key, struct rhlist_head *list, | |
723 | const struct rhashtable_params params) | |
724 | { | |
725 | return PTR_ERR(__rhashtable_insert_fast(&hlt->ht, key, &list->rhead, | |
726 | params, true)); | |
727 | } | |
728 | ||
729 | /** | |
730 | * rhltable_insert - insert object into hash list table | |
731 | * @hlt: hash list table | |
732 | * @list: pointer to hash list head inside object | |
733 | * @params: hash table parameters | |
734 | * | |
735 | * Will take a per bucket spinlock to protect against mutual mutations | |
736 | * on the same bucket. Multiple insertions may occur in parallel unless | |
737 | * they map to the same bucket lock. | |
738 | * | |
739 | * It is safe to call this function from atomic context. | |
740 | * | |
0c6f69a5 N |
741 | * Will trigger an automatic deferred table resizing if residency in the |
742 | * table grows beyond 70%. | |
ca26893f HX |
743 | */ |
744 | static inline int rhltable_insert( | |
745 | struct rhltable *hlt, struct rhlist_head *list, | |
746 | const struct rhashtable_params params) | |
747 | { | |
748 | const char *key = rht_obj(&hlt->ht, &list->rhead); | |
749 | ||
750 | key += params.key_offset; | |
751 | ||
752 | return rhltable_insert_key(hlt, key, list, params); | |
753 | } | |
754 | ||
02fd97c3 HX |
755 | /** |
756 | * rhashtable_lookup_insert_fast - lookup and insert object into hash table | |
757 | * @ht: hash table | |
758 | * @obj: pointer to hash head inside object | |
759 | * @params: hash table parameters | |
760 | * | |
761 | * Locks down the bucket chain in both the old and new table if a resize | |
762 | * is in progress to ensure that writers can't remove from the old table | |
763 | * and can't insert to the new table during the atomic operation of search | |
764 | * and insertion. Searches for duplicates in both the old and new table if | |
765 | * a resize is in progress. | |
766 | * | |
767 | * This lookup function may only be used for fixed key hash table (key_len | |
768 | * parameter set). It will BUG() if used inappropriately. | |
769 | * | |
770 | * It is safe to call this function from atomic context. | |
771 | * | |
0c6f69a5 N |
772 | * Will trigger an automatic deferred table resizing if residency in the |
773 | * table grows beyond 70%. | |
02fd97c3 HX |
774 | */ |
775 | static inline int rhashtable_lookup_insert_fast( | |
776 | struct rhashtable *ht, struct rhash_head *obj, | |
777 | const struct rhashtable_params params) | |
778 | { | |
779 | const char *key = rht_obj(ht, obj); | |
5ca8cc5b | 780 | void *ret; |
02fd97c3 HX |
781 | |
782 | BUG_ON(ht->p.obj_hashfn); | |
783 | ||
ca26893f HX |
784 | ret = __rhashtable_insert_fast(ht, key + ht->p.key_offset, obj, params, |
785 | false); | |
5ca8cc5b PNA |
786 | if (IS_ERR(ret)) |
787 | return PTR_ERR(ret); | |
788 | ||
789 | return ret == NULL ? 0 : -EEXIST; | |
02fd97c3 HX |
790 | } |
791 | ||
f9fe1c12 AG |
792 | /** |
793 | * rhashtable_lookup_get_insert_fast - lookup and insert object into hash table | |
794 | * @ht: hash table | |
795 | * @obj: pointer to hash head inside object | |
796 | * @params: hash table parameters | |
797 | * | |
798 | * Just like rhashtable_lookup_insert_fast(), but this function returns the | |
799 | * object if it exists, NULL if it did not and the insertion was successful, | |
800 | * and an ERR_PTR otherwise. | |
801 | */ | |
802 | static inline void *rhashtable_lookup_get_insert_fast( | |
803 | struct rhashtable *ht, struct rhash_head *obj, | |
804 | const struct rhashtable_params params) | |
805 | { | |
806 | const char *key = rht_obj(ht, obj); | |
807 | ||
808 | BUG_ON(ht->p.obj_hashfn); | |
809 | ||
810 | return __rhashtable_insert_fast(ht, key + ht->p.key_offset, obj, params, | |
811 | false); | |
812 | } | |
813 | ||
02fd97c3 HX |
814 | /** |
815 | * rhashtable_lookup_insert_key - search and insert object to hash table | |
816 | * with explicit key | |
817 | * @ht: hash table | |
818 | * @key: key | |
819 | * @obj: pointer to hash head inside object | |
820 | * @params: hash table parameters | |
821 | * | |
822 | * Locks down the bucket chain in both the old and new table if a resize | |
823 | * is in progress to ensure that writers can't remove from the old table | |
824 | * and can't insert to the new table during the atomic operation of search | |
825 | * and insertion. Searches for duplicates in both the old and new table if | |
826 | * a resize is in progress. | |
827 | * | |
828 | * Lookups may occur in parallel with hashtable mutations and resizing. | |
829 | * | |
0c6f69a5 N |
830 | * Will trigger an automatic deferred table resizing if residency in the |
831 | * table grows beyond 70%. | |
02fd97c3 HX |
832 | * |
833 | * Returns zero on success. | |
834 | */ | |
835 | static inline int rhashtable_lookup_insert_key( | |
836 | struct rhashtable *ht, const void *key, struct rhash_head *obj, | |
837 | const struct rhashtable_params params) | |
5ca8cc5b PNA |
838 | { |
839 | void *ret; | |
840 | ||
841 | BUG_ON(!ht->p.obj_hashfn || !key); | |
842 | ||
ca26893f | 843 | ret = __rhashtable_insert_fast(ht, key, obj, params, false); |
5ca8cc5b PNA |
844 | if (IS_ERR(ret)) |
845 | return PTR_ERR(ret); | |
846 | ||
847 | return ret == NULL ? 0 : -EEXIST; | |
848 | } | |
849 | ||
850 | /** | |
851 | * rhashtable_lookup_get_insert_key - lookup and insert object into hash table | |
852 | * @ht: hash table | |
853 | * @obj: pointer to hash head inside object | |
854 | * @params: hash table parameters | |
855 | * @data: pointer to element data already in hashes | |
856 | * | |
857 | * Just like rhashtable_lookup_insert_key(), but this function returns the | |
858 | * object if it exists, NULL if it does not and the insertion was successful, | |
859 | * and an ERR_PTR otherwise. | |
860 | */ | |
861 | static inline void *rhashtable_lookup_get_insert_key( | |
862 | struct rhashtable *ht, const void *key, struct rhash_head *obj, | |
863 | const struct rhashtable_params params) | |
02fd97c3 HX |
864 | { |
865 | BUG_ON(!ht->p.obj_hashfn || !key); | |
866 | ||
ca26893f | 867 | return __rhashtable_insert_fast(ht, key, obj, params, false); |
02fd97c3 HX |
868 | } |
869 | ||
ac833bdd | 870 | /* Internal function, please use rhashtable_remove_fast() instead */ |
ca26893f | 871 | static inline int __rhashtable_remove_fast_one( |
02fd97c3 | 872 | struct rhashtable *ht, struct bucket_table *tbl, |
ca26893f HX |
873 | struct rhash_head *obj, const struct rhashtable_params params, |
874 | bool rhlist) | |
02fd97c3 HX |
875 | { |
876 | struct rhash_head __rcu **pprev; | |
877 | struct rhash_head *he; | |
878 | spinlock_t * lock; | |
299e5c32 | 879 | unsigned int hash; |
02fd97c3 HX |
880 | int err = -ENOENT; |
881 | ||
882 | hash = rht_head_hashfn(ht, tbl, obj, params); | |
883 | lock = rht_bucket_lock(tbl, hash); | |
884 | ||
885 | spin_lock_bh(lock); | |
886 | ||
da20420f HX |
887 | pprev = rht_bucket_var(tbl, hash); |
888 | rht_for_each_continue(he, *pprev, tbl, hash) { | |
ca26893f HX |
889 | struct rhlist_head *list; |
890 | ||
891 | list = container_of(he, struct rhlist_head, rhead); | |
892 | ||
02fd97c3 | 893 | if (he != obj) { |
ca26893f HX |
894 | struct rhlist_head __rcu **lpprev; |
895 | ||
02fd97c3 | 896 | pprev = &he->next; |
ca26893f HX |
897 | |
898 | if (!rhlist) | |
899 | continue; | |
900 | ||
901 | do { | |
902 | lpprev = &list->next; | |
903 | list = rht_dereference_bucket(list->next, | |
904 | tbl, hash); | |
905 | } while (list && obj != &list->rhead); | |
906 | ||
907 | if (!list) | |
908 | continue; | |
909 | ||
910 | list = rht_dereference_bucket(list->next, tbl, hash); | |
911 | RCU_INIT_POINTER(*lpprev, list); | |
912 | err = 0; | |
913 | break; | |
02fd97c3 HX |
914 | } |
915 | ||
ca26893f HX |
916 | obj = rht_dereference_bucket(obj->next, tbl, hash); |
917 | err = 1; | |
918 | ||
919 | if (rhlist) { | |
920 | list = rht_dereference_bucket(list->next, tbl, hash); | |
921 | if (list) { | |
922 | RCU_INIT_POINTER(list->rhead.next, obj); | |
923 | obj = &list->rhead; | |
924 | err = 0; | |
925 | } | |
926 | } | |
927 | ||
928 | rcu_assign_pointer(*pprev, obj); | |
02fd97c3 HX |
929 | break; |
930 | } | |
931 | ||
932 | spin_unlock_bh(lock); | |
933 | ||
ca26893f HX |
934 | if (err > 0) { |
935 | atomic_dec(&ht->nelems); | |
936 | if (unlikely(ht->p.automatic_shrinking && | |
937 | rht_shrink_below_30(ht, tbl))) | |
938 | schedule_work(&ht->run_work); | |
939 | err = 0; | |
940 | } | |
941 | ||
02fd97c3 HX |
942 | return err; |
943 | } | |
944 | ||
ca26893f HX |
945 | /* Internal function, please use rhashtable_remove_fast() instead */ |
946 | static inline int __rhashtable_remove_fast( | |
02fd97c3 | 947 | struct rhashtable *ht, struct rhash_head *obj, |
ca26893f | 948 | const struct rhashtable_params params, bool rhlist) |
02fd97c3 HX |
949 | { |
950 | struct bucket_table *tbl; | |
951 | int err; | |
952 | ||
953 | rcu_read_lock(); | |
954 | ||
955 | tbl = rht_dereference_rcu(ht->tbl, ht); | |
956 | ||
957 | /* Because we have already taken (and released) the bucket | |
958 | * lock in old_tbl, if we find that future_tbl is not yet | |
959 | * visible then that guarantees the entry to still be in | |
960 | * the old tbl if it exists. | |
961 | */ | |
ca26893f HX |
962 | while ((err = __rhashtable_remove_fast_one(ht, tbl, obj, params, |
963 | rhlist)) && | |
02fd97c3 HX |
964 | (tbl = rht_dereference_rcu(tbl->future_tbl, ht))) |
965 | ; | |
966 | ||
02fd97c3 HX |
967 | rcu_read_unlock(); |
968 | ||
969 | return err; | |
970 | } | |
971 | ||
ca26893f HX |
972 | /** |
973 | * rhashtable_remove_fast - remove object from hash table | |
974 | * @ht: hash table | |
975 | * @obj: pointer to hash head inside object | |
976 | * @params: hash table parameters | |
977 | * | |
978 | * Since the hash chain is single linked, the removal operation needs to | |
979 | * walk the bucket chain upon removal. The removal operation is thus | |
980 | * considerable slow if the hash table is not correctly sized. | |
981 | * | |
0c6f69a5 N |
982 | * Will automatically shrink the table if permitted when residency drops |
983 | * below 30%. | |
ca26893f HX |
984 | * |
985 | * Returns zero on success, -ENOENT if the entry could not be found. | |
986 | */ | |
987 | static inline int rhashtable_remove_fast( | |
988 | struct rhashtable *ht, struct rhash_head *obj, | |
989 | const struct rhashtable_params params) | |
990 | { | |
991 | return __rhashtable_remove_fast(ht, obj, params, false); | |
992 | } | |
993 | ||
994 | /** | |
995 | * rhltable_remove - remove object from hash list table | |
996 | * @hlt: hash list table | |
997 | * @list: pointer to hash list head inside object | |
998 | * @params: hash table parameters | |
999 | * | |
1000 | * Since the hash chain is single linked, the removal operation needs to | |
1001 | * walk the bucket chain upon removal. The removal operation is thus | |
1002 | * considerable slow if the hash table is not correctly sized. | |
1003 | * | |
0c6f69a5 N |
1004 | * Will automatically shrink the table if permitted when residency drops |
1005 | * below 30% | |
ca26893f HX |
1006 | * |
1007 | * Returns zero on success, -ENOENT if the entry could not be found. | |
1008 | */ | |
1009 | static inline int rhltable_remove( | |
1010 | struct rhltable *hlt, struct rhlist_head *list, | |
1011 | const struct rhashtable_params params) | |
1012 | { | |
1013 | return __rhashtable_remove_fast(&hlt->ht, &list->rhead, params, true); | |
1014 | } | |
1015 | ||
3502cad7 TH |
1016 | /* Internal function, please use rhashtable_replace_fast() instead */ |
1017 | static inline int __rhashtable_replace_fast( | |
1018 | struct rhashtable *ht, struct bucket_table *tbl, | |
1019 | struct rhash_head *obj_old, struct rhash_head *obj_new, | |
1020 | const struct rhashtable_params params) | |
1021 | { | |
1022 | struct rhash_head __rcu **pprev; | |
1023 | struct rhash_head *he; | |
1024 | spinlock_t *lock; | |
1025 | unsigned int hash; | |
1026 | int err = -ENOENT; | |
1027 | ||
1028 | /* Minimally, the old and new objects must have same hash | |
1029 | * (which should mean identifiers are the same). | |
1030 | */ | |
1031 | hash = rht_head_hashfn(ht, tbl, obj_old, params); | |
1032 | if (hash != rht_head_hashfn(ht, tbl, obj_new, params)) | |
1033 | return -EINVAL; | |
1034 | ||
1035 | lock = rht_bucket_lock(tbl, hash); | |
1036 | ||
1037 | spin_lock_bh(lock); | |
1038 | ||
da20420f HX |
1039 | pprev = rht_bucket_var(tbl, hash); |
1040 | rht_for_each_continue(he, *pprev, tbl, hash) { | |
3502cad7 TH |
1041 | if (he != obj_old) { |
1042 | pprev = &he->next; | |
1043 | continue; | |
1044 | } | |
1045 | ||
1046 | rcu_assign_pointer(obj_new->next, obj_old->next); | |
1047 | rcu_assign_pointer(*pprev, obj_new); | |
1048 | err = 0; | |
1049 | break; | |
1050 | } | |
1051 | ||
1052 | spin_unlock_bh(lock); | |
1053 | ||
1054 | return err; | |
1055 | } | |
1056 | ||
1057 | /** | |
1058 | * rhashtable_replace_fast - replace an object in hash table | |
1059 | * @ht: hash table | |
1060 | * @obj_old: pointer to hash head inside object being replaced | |
1061 | * @obj_new: pointer to hash head inside object which is new | |
1062 | * @params: hash table parameters | |
1063 | * | |
1064 | * Replacing an object doesn't affect the number of elements in the hash table | |
1065 | * or bucket, so we don't need to worry about shrinking or expanding the | |
1066 | * table here. | |
1067 | * | |
1068 | * Returns zero on success, -ENOENT if the entry could not be found, | |
1069 | * -EINVAL if hash is not the same for the old and new objects. | |
1070 | */ | |
1071 | static inline int rhashtable_replace_fast( | |
1072 | struct rhashtable *ht, struct rhash_head *obj_old, | |
1073 | struct rhash_head *obj_new, | |
1074 | const struct rhashtable_params params) | |
1075 | { | |
1076 | struct bucket_table *tbl; | |
1077 | int err; | |
1078 | ||
1079 | rcu_read_lock(); | |
1080 | ||
1081 | tbl = rht_dereference_rcu(ht->tbl, ht); | |
1082 | ||
1083 | /* Because we have already taken (and released) the bucket | |
1084 | * lock in old_tbl, if we find that future_tbl is not yet | |
1085 | * visible then that guarantees the entry to still be in | |
1086 | * the old tbl if it exists. | |
1087 | */ | |
1088 | while ((err = __rhashtable_replace_fast(ht, tbl, obj_old, | |
1089 | obj_new, params)) && | |
1090 | (tbl = rht_dereference_rcu(tbl->future_tbl, ht))) | |
1091 | ; | |
1092 | ||
1093 | rcu_read_unlock(); | |
1094 | ||
1095 | return err; | |
1096 | } | |
1097 | ||
246779dd HX |
1098 | /* Obsolete function, do not use in new code. */ |
1099 | static inline int rhashtable_walk_init(struct rhashtable *ht, | |
1100 | struct rhashtable_iter *iter, gfp_t gfp) | |
1101 | { | |
1102 | rhashtable_walk_enter(ht, iter); | |
1103 | return 0; | |
1104 | } | |
1105 | ||
ca26893f HX |
1106 | /** |
1107 | * rhltable_walk_enter - Initialise an iterator | |
1108 | * @hlt: Table to walk over | |
1109 | * @iter: Hash table Iterator | |
1110 | * | |
1111 | * This function prepares a hash table walk. | |
1112 | * | |
1113 | * Note that if you restart a walk after rhashtable_walk_stop you | |
1114 | * may see the same object twice. Also, you may miss objects if | |
1115 | * there are removals in between rhashtable_walk_stop and the next | |
1116 | * call to rhashtable_walk_start. | |
1117 | * | |
1118 | * For a completely stable walk you should construct your own data | |
1119 | * structure outside the hash table. | |
1120 | * | |
82266e98 N |
1121 | * This function may be called from any process context, including |
1122 | * non-preemptable context, but cannot be called from softirq or | |
1123 | * hardirq context. | |
ca26893f HX |
1124 | * |
1125 | * You must call rhashtable_walk_exit after this function returns. | |
1126 | */ | |
1127 | static inline void rhltable_walk_enter(struct rhltable *hlt, | |
1128 | struct rhashtable_iter *iter) | |
1129 | { | |
1130 | return rhashtable_walk_enter(&hlt->ht, iter); | |
1131 | } | |
1132 | ||
1133 | /** | |
1134 | * rhltable_free_and_destroy - free elements and destroy hash list table | |
1135 | * @hlt: the hash list table to destroy | |
1136 | * @free_fn: callback to release resources of element | |
1137 | * @arg: pointer passed to free_fn | |
1138 | * | |
1139 | * See documentation for rhashtable_free_and_destroy. | |
1140 | */ | |
1141 | static inline void rhltable_free_and_destroy(struct rhltable *hlt, | |
1142 | void (*free_fn)(void *ptr, | |
1143 | void *arg), | |
1144 | void *arg) | |
1145 | { | |
1146 | return rhashtable_free_and_destroy(&hlt->ht, free_fn, arg); | |
1147 | } | |
1148 | ||
1149 | static inline void rhltable_destroy(struct rhltable *hlt) | |
1150 | { | |
1151 | return rhltable_free_and_destroy(hlt, NULL, NULL); | |
1152 | } | |
1153 | ||
7e1e7763 | 1154 | #endif /* _LINUX_RHASHTABLE_H */ |