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7e1e7763 TG |
1 | /* |
2 | * Resizable, Scalable, Concurrent Hash Table | |
3 | * | |
ca26893f | 4 | * Copyright (c) 2015-2016 Herbert Xu <herbert@gondor.apana.org.au> |
b5e2c150 | 5 | * Copyright (c) 2014-2015 Thomas Graf <tgraf@suug.ch> |
7e1e7763 TG |
6 | * Copyright (c) 2008-2014 Patrick McHardy <kaber@trash.net> |
7 | * | |
7e1e7763 | 8 | * Code partially derived from nft_hash |
dc0ee268 HX |
9 | * Rewritten with rehash code from br_multicast plus single list |
10 | * pointer as suggested by Josh Triplett | |
7e1e7763 TG |
11 | * |
12 | * This program is free software; you can redistribute it and/or modify | |
13 | * it under the terms of the GNU General Public License version 2 as | |
14 | * published by the Free Software Foundation. | |
15 | */ | |
16 | ||
17 | #ifndef _LINUX_RHASHTABLE_H | |
18 | #define _LINUX_RHASHTABLE_H | |
19 | ||
07ee0722 | 20 | #include <linux/atomic.h> |
f2dba9c6 | 21 | #include <linux/compiler.h> |
3cf92222 | 22 | #include <linux/err.h> |
6626af69 | 23 | #include <linux/errno.h> |
31ccde2d | 24 | #include <linux/jhash.h> |
f89bd6f8 | 25 | #include <linux/list_nulls.h> |
97defe1e | 26 | #include <linux/workqueue.h> |
86b35b64 | 27 | #include <linux/mutex.h> |
02fd97c3 | 28 | #include <linux/rcupdate.h> |
7e1e7763 | 29 | |
f89bd6f8 TG |
30 | /* |
31 | * The end of the chain is marked with a special nulls marks which has | |
32 | * the following format: | |
33 | * | |
34 | * +-------+-----------------------------------------------------+-+ | |
35 | * | Base | Hash |1| | |
36 | * +-------+-----------------------------------------------------+-+ | |
37 | * | |
38 | * Base (4 bits) : Reserved to distinguish between multiple tables. | |
39 | * Specified via &struct rhashtable_params.nulls_base. | |
40 | * Hash (27 bits): Full hash (unmasked) of first element added to bucket | |
41 | * 1 (1 bit) : Nulls marker (always set) | |
42 | * | |
43 | * The remaining bits of the next pointer remain unused for now. | |
44 | */ | |
45 | #define RHT_BASE_BITS 4 | |
46 | #define RHT_HASH_BITS 27 | |
47 | #define RHT_BASE_SHIFT RHT_HASH_BITS | |
48 | ||
02fd97c3 HX |
49 | /* Base bits plus 1 bit for nulls marker */ |
50 | #define RHT_HASH_RESERVED_SPACE (RHT_BASE_BITS + 1) | |
51 | ||
7e1e7763 | 52 | struct rhash_head { |
5300fdcb | 53 | struct rhash_head __rcu *next; |
7e1e7763 TG |
54 | }; |
55 | ||
ca26893f HX |
56 | struct rhlist_head { |
57 | struct rhash_head rhead; | |
58 | struct rhlist_head __rcu *next; | |
59 | }; | |
60 | ||
97defe1e TG |
61 | /** |
62 | * struct bucket_table - Table of hash buckets | |
63 | * @size: Number of hash buckets | |
63d512d0 | 64 | * @rehash: Current bucket being rehashed |
988dfbd7 | 65 | * @hash_rnd: Random seed to fold into hash |
97defe1e TG |
66 | * @locks_mask: Mask to apply before accessing locks[] |
67 | * @locks: Array of spinlocks protecting individual buckets | |
eddee5ba | 68 | * @walkers: List of active walkers |
9d901bc0 | 69 | * @rcu: RCU structure for freeing the table |
c4db8848 | 70 | * @future_tbl: Table under construction during rehashing |
97defe1e TG |
71 | * @buckets: size * hash buckets |
72 | */ | |
7e1e7763 | 73 | struct bucket_table { |
63d512d0 HX |
74 | unsigned int size; |
75 | unsigned int rehash; | |
988dfbd7 | 76 | u32 hash_rnd; |
b9ebafbe ED |
77 | unsigned int locks_mask; |
78 | spinlock_t *locks; | |
eddee5ba | 79 | struct list_head walkers; |
9d901bc0 | 80 | struct rcu_head rcu; |
b9ebafbe | 81 | |
c4db8848 HX |
82 | struct bucket_table __rcu *future_tbl; |
83 | ||
b9ebafbe | 84 | struct rhash_head __rcu *buckets[] ____cacheline_aligned_in_smp; |
7e1e7763 TG |
85 | }; |
86 | ||
02fd97c3 HX |
87 | /** |
88 | * struct rhashtable_compare_arg - Key for the function rhashtable_compare | |
89 | * @ht: Hash table | |
90 | * @key: Key to compare against | |
91 | */ | |
92 | struct rhashtable_compare_arg { | |
93 | struct rhashtable *ht; | |
94 | const void *key; | |
95 | }; | |
96 | ||
7e1e7763 | 97 | typedef u32 (*rht_hashfn_t)(const void *data, u32 len, u32 seed); |
49f7b33e | 98 | typedef u32 (*rht_obj_hashfn_t)(const void *data, u32 len, u32 seed); |
02fd97c3 HX |
99 | typedef int (*rht_obj_cmpfn_t)(struct rhashtable_compare_arg *arg, |
100 | const void *obj); | |
7e1e7763 TG |
101 | |
102 | struct rhashtable; | |
103 | ||
104 | /** | |
105 | * struct rhashtable_params - Hash table construction parameters | |
106 | * @nelem_hint: Hint on number of elements, should be 75% of desired size | |
107 | * @key_len: Length of key | |
108 | * @key_offset: Offset of key in struct to be hashed | |
109 | * @head_offset: Offset of rhash_head in struct to be hashed | |
07ee0722 | 110 | * @insecure_max_entries: Maximum number of entries (may be exceeded) |
c2e213cf HX |
111 | * @max_size: Maximum size while expanding |
112 | * @min_size: Minimum size while shrinking | |
f89bd6f8 | 113 | * @nulls_base: Base value to generate nulls marker |
ccd57b1b | 114 | * @insecure_elasticity: Set to true to disable chain length checks |
b5e2c150 | 115 | * @automatic_shrinking: Enable automatic shrinking of tables |
97defe1e | 116 | * @locks_mul: Number of bucket locks to allocate per cpu (default: 128) |
31ccde2d | 117 | * @hashfn: Hash function (default: jhash2 if !(key_len % 4), or jhash) |
7e1e7763 | 118 | * @obj_hashfn: Function to hash object |
02fd97c3 | 119 | * @obj_cmpfn: Function to compare key with object |
7e1e7763 TG |
120 | */ |
121 | struct rhashtable_params { | |
122 | size_t nelem_hint; | |
123 | size_t key_len; | |
124 | size_t key_offset; | |
125 | size_t head_offset; | |
07ee0722 | 126 | unsigned int insecure_max_entries; |
c2e213cf HX |
127 | unsigned int max_size; |
128 | unsigned int min_size; | |
f89bd6f8 | 129 | u32 nulls_base; |
ccd57b1b | 130 | bool insecure_elasticity; |
b5e2c150 | 131 | bool automatic_shrinking; |
97defe1e | 132 | size_t locks_mul; |
7e1e7763 TG |
133 | rht_hashfn_t hashfn; |
134 | rht_obj_hashfn_t obj_hashfn; | |
02fd97c3 | 135 | rht_obj_cmpfn_t obj_cmpfn; |
7e1e7763 TG |
136 | }; |
137 | ||
138 | /** | |
139 | * struct rhashtable - Hash table handle | |
140 | * @tbl: Bucket table | |
141 | * @nelems: Number of elements in table | |
31ccde2d | 142 | * @key_len: Key length for hashfn |
ccd57b1b | 143 | * @elasticity: Maximum chain length before rehash |
7e1e7763 | 144 | * @p: Configuration parameters |
ca26893f | 145 | * @rhlist: True if this is an rhltable |
97defe1e TG |
146 | * @run_work: Deferred worker to expand/shrink asynchronously |
147 | * @mutex: Mutex to protect current/future table swapping | |
ba7c95ea | 148 | * @lock: Spin lock to protect walker list |
7e1e7763 TG |
149 | */ |
150 | struct rhashtable { | |
151 | struct bucket_table __rcu *tbl; | |
97defe1e | 152 | atomic_t nelems; |
31ccde2d | 153 | unsigned int key_len; |
ccd57b1b | 154 | unsigned int elasticity; |
7e1e7763 | 155 | struct rhashtable_params p; |
ca26893f | 156 | bool rhlist; |
57699a40 | 157 | struct work_struct run_work; |
97defe1e | 158 | struct mutex mutex; |
ba7c95ea | 159 | spinlock_t lock; |
7e1e7763 TG |
160 | }; |
161 | ||
ca26893f HX |
162 | /** |
163 | * struct rhltable - Hash table with duplicate objects in a list | |
164 | * @ht: Underlying rhtable | |
165 | */ | |
166 | struct rhltable { | |
167 | struct rhashtable ht; | |
168 | }; | |
169 | ||
f2dba9c6 HX |
170 | /** |
171 | * struct rhashtable_walker - Hash table walker | |
172 | * @list: List entry on list of walkers | |
eddee5ba | 173 | * @tbl: The table that we were walking over |
f2dba9c6 HX |
174 | */ |
175 | struct rhashtable_walker { | |
176 | struct list_head list; | |
eddee5ba | 177 | struct bucket_table *tbl; |
f2dba9c6 HX |
178 | }; |
179 | ||
180 | /** | |
ca26893f | 181 | * struct rhashtable_iter - Hash table iterator |
f2dba9c6 HX |
182 | * @ht: Table to iterate through |
183 | * @p: Current pointer | |
ca26893f | 184 | * @list: Current hash list pointer |
f2dba9c6 HX |
185 | * @walker: Associated rhashtable walker |
186 | * @slot: Current slot | |
187 | * @skip: Number of entries to skip in slot | |
188 | */ | |
189 | struct rhashtable_iter { | |
190 | struct rhashtable *ht; | |
191 | struct rhash_head *p; | |
ca26893f | 192 | struct rhlist_head *list; |
246779dd | 193 | struct rhashtable_walker walker; |
f2dba9c6 HX |
194 | unsigned int slot; |
195 | unsigned int skip; | |
196 | }; | |
197 | ||
f89bd6f8 TG |
198 | static inline unsigned long rht_marker(const struct rhashtable *ht, u32 hash) |
199 | { | |
200 | return NULLS_MARKER(ht->p.nulls_base + hash); | |
201 | } | |
202 | ||
203 | #define INIT_RHT_NULLS_HEAD(ptr, ht, hash) \ | |
204 | ((ptr) = (typeof(ptr)) rht_marker(ht, hash)) | |
205 | ||
206 | static inline bool rht_is_a_nulls(const struct rhash_head *ptr) | |
207 | { | |
208 | return ((unsigned long) ptr & 1); | |
209 | } | |
210 | ||
211 | static inline unsigned long rht_get_nulls_value(const struct rhash_head *ptr) | |
212 | { | |
213 | return ((unsigned long) ptr) >> 1; | |
214 | } | |
215 | ||
02fd97c3 HX |
216 | static inline void *rht_obj(const struct rhashtable *ht, |
217 | const struct rhash_head *he) | |
218 | { | |
219 | return (char *)he - ht->p.head_offset; | |
220 | } | |
221 | ||
222 | static inline unsigned int rht_bucket_index(const struct bucket_table *tbl, | |
223 | unsigned int hash) | |
224 | { | |
225 | return (hash >> RHT_HASH_RESERVED_SPACE) & (tbl->size - 1); | |
226 | } | |
227 | ||
228 | static inline unsigned int rht_key_hashfn( | |
229 | struct rhashtable *ht, const struct bucket_table *tbl, | |
230 | const void *key, const struct rhashtable_params params) | |
231 | { | |
299e5c32 | 232 | unsigned int hash; |
de91b25c | 233 | |
31ccde2d HX |
234 | /* params must be equal to ht->p if it isn't constant. */ |
235 | if (!__builtin_constant_p(params.key_len)) | |
236 | hash = ht->p.hashfn(key, ht->key_len, tbl->hash_rnd); | |
237 | else if (params.key_len) { | |
299e5c32 | 238 | unsigned int key_len = params.key_len; |
31ccde2d HX |
239 | |
240 | if (params.hashfn) | |
241 | hash = params.hashfn(key, key_len, tbl->hash_rnd); | |
242 | else if (key_len & (sizeof(u32) - 1)) | |
243 | hash = jhash(key, key_len, tbl->hash_rnd); | |
244 | else | |
245 | hash = jhash2(key, key_len / sizeof(u32), | |
246 | tbl->hash_rnd); | |
247 | } else { | |
299e5c32 | 248 | unsigned int key_len = ht->p.key_len; |
31ccde2d HX |
249 | |
250 | if (params.hashfn) | |
251 | hash = params.hashfn(key, key_len, tbl->hash_rnd); | |
252 | else | |
253 | hash = jhash(key, key_len, tbl->hash_rnd); | |
254 | } | |
255 | ||
256 | return rht_bucket_index(tbl, hash); | |
02fd97c3 HX |
257 | } |
258 | ||
259 | static inline unsigned int rht_head_hashfn( | |
260 | struct rhashtable *ht, const struct bucket_table *tbl, | |
261 | const struct rhash_head *he, const struct rhashtable_params params) | |
262 | { | |
263 | const char *ptr = rht_obj(ht, he); | |
264 | ||
265 | return likely(params.obj_hashfn) ? | |
49f7b33e PM |
266 | rht_bucket_index(tbl, params.obj_hashfn(ptr, params.key_len ?: |
267 | ht->p.key_len, | |
268 | tbl->hash_rnd)) : | |
02fd97c3 HX |
269 | rht_key_hashfn(ht, tbl, ptr + params.key_offset, params); |
270 | } | |
271 | ||
272 | /** | |
273 | * rht_grow_above_75 - returns true if nelems > 0.75 * table-size | |
274 | * @ht: hash table | |
275 | * @tbl: current table | |
276 | */ | |
277 | static inline bool rht_grow_above_75(const struct rhashtable *ht, | |
278 | const struct bucket_table *tbl) | |
279 | { | |
280 | /* Expand table when exceeding 75% load */ | |
281 | return atomic_read(&ht->nelems) > (tbl->size / 4 * 3) && | |
282 | (!ht->p.max_size || tbl->size < ht->p.max_size); | |
283 | } | |
284 | ||
285 | /** | |
286 | * rht_shrink_below_30 - returns true if nelems < 0.3 * table-size | |
287 | * @ht: hash table | |
288 | * @tbl: current table | |
289 | */ | |
290 | static inline bool rht_shrink_below_30(const struct rhashtable *ht, | |
291 | const struct bucket_table *tbl) | |
292 | { | |
293 | /* Shrink table beneath 30% load */ | |
294 | return atomic_read(&ht->nelems) < (tbl->size * 3 / 10) && | |
295 | tbl->size > ht->p.min_size; | |
296 | } | |
297 | ||
ccd57b1b HX |
298 | /** |
299 | * rht_grow_above_100 - returns true if nelems > table-size | |
300 | * @ht: hash table | |
301 | * @tbl: current table | |
302 | */ | |
303 | static inline bool rht_grow_above_100(const struct rhashtable *ht, | |
304 | const struct bucket_table *tbl) | |
305 | { | |
1d8dc3d3 JB |
306 | return atomic_read(&ht->nelems) > tbl->size && |
307 | (!ht->p.max_size || tbl->size < ht->p.max_size); | |
ccd57b1b HX |
308 | } |
309 | ||
07ee0722 HX |
310 | /** |
311 | * rht_grow_above_max - returns true if table is above maximum | |
312 | * @ht: hash table | |
313 | * @tbl: current table | |
314 | */ | |
315 | static inline bool rht_grow_above_max(const struct rhashtable *ht, | |
316 | const struct bucket_table *tbl) | |
317 | { | |
318 | return ht->p.insecure_max_entries && | |
319 | atomic_read(&ht->nelems) >= ht->p.insecure_max_entries; | |
320 | } | |
321 | ||
02fd97c3 HX |
322 | /* The bucket lock is selected based on the hash and protects mutations |
323 | * on a group of hash buckets. | |
324 | * | |
325 | * A maximum of tbl->size/2 bucket locks is allocated. This ensures that | |
326 | * a single lock always covers both buckets which may both contains | |
327 | * entries which link to the same bucket of the old table during resizing. | |
328 | * This allows to simplify the locking as locking the bucket in both | |
329 | * tables during resize always guarantee protection. | |
330 | * | |
331 | * IMPORTANT: When holding the bucket lock of both the old and new table | |
332 | * during expansions and shrinking, the old bucket lock must always be | |
333 | * acquired first. | |
334 | */ | |
335 | static inline spinlock_t *rht_bucket_lock(const struct bucket_table *tbl, | |
336 | unsigned int hash) | |
337 | { | |
338 | return &tbl->locks[hash & tbl->locks_mask]; | |
339 | } | |
340 | ||
7e1e7763 | 341 | #ifdef CONFIG_PROVE_LOCKING |
97defe1e | 342 | int lockdep_rht_mutex_is_held(struct rhashtable *ht); |
88d6ed15 | 343 | int lockdep_rht_bucket_is_held(const struct bucket_table *tbl, u32 hash); |
7e1e7763 | 344 | #else |
97defe1e | 345 | static inline int lockdep_rht_mutex_is_held(struct rhashtable *ht) |
7e1e7763 TG |
346 | { |
347 | return 1; | |
348 | } | |
88d6ed15 TG |
349 | |
350 | static inline int lockdep_rht_bucket_is_held(const struct bucket_table *tbl, | |
351 | u32 hash) | |
352 | { | |
353 | return 1; | |
354 | } | |
7e1e7763 TG |
355 | #endif /* CONFIG_PROVE_LOCKING */ |
356 | ||
488fb86e HX |
357 | int rhashtable_init(struct rhashtable *ht, |
358 | const struct rhashtable_params *params); | |
ca26893f HX |
359 | int rhltable_init(struct rhltable *hlt, |
360 | const struct rhashtable_params *params); | |
7e1e7763 | 361 | |
ca26893f HX |
362 | void *rhashtable_insert_slow(struct rhashtable *ht, const void *key, |
363 | struct rhash_head *obj); | |
7e1e7763 | 364 | |
246779dd HX |
365 | void rhashtable_walk_enter(struct rhashtable *ht, |
366 | struct rhashtable_iter *iter); | |
f2dba9c6 HX |
367 | void rhashtable_walk_exit(struct rhashtable_iter *iter); |
368 | int rhashtable_walk_start(struct rhashtable_iter *iter) __acquires(RCU); | |
369 | void *rhashtable_walk_next(struct rhashtable_iter *iter); | |
370 | void rhashtable_walk_stop(struct rhashtable_iter *iter) __releases(RCU); | |
371 | ||
6b6f302c TG |
372 | void rhashtable_free_and_destroy(struct rhashtable *ht, |
373 | void (*free_fn)(void *ptr, void *arg), | |
374 | void *arg); | |
97defe1e | 375 | void rhashtable_destroy(struct rhashtable *ht); |
7e1e7763 TG |
376 | |
377 | #define rht_dereference(p, ht) \ | |
378 | rcu_dereference_protected(p, lockdep_rht_mutex_is_held(ht)) | |
379 | ||
380 | #define rht_dereference_rcu(p, ht) \ | |
381 | rcu_dereference_check(p, lockdep_rht_mutex_is_held(ht)) | |
382 | ||
88d6ed15 TG |
383 | #define rht_dereference_bucket(p, tbl, hash) \ |
384 | rcu_dereference_protected(p, lockdep_rht_bucket_is_held(tbl, hash)) | |
7e1e7763 | 385 | |
88d6ed15 TG |
386 | #define rht_dereference_bucket_rcu(p, tbl, hash) \ |
387 | rcu_dereference_check(p, lockdep_rht_bucket_is_held(tbl, hash)) | |
388 | ||
389 | #define rht_entry(tpos, pos, member) \ | |
390 | ({ tpos = container_of(pos, typeof(*tpos), member); 1; }) | |
7e1e7763 TG |
391 | |
392 | /** | |
88d6ed15 TG |
393 | * rht_for_each_continue - continue iterating over hash chain |
394 | * @pos: the &struct rhash_head to use as a loop cursor. | |
395 | * @head: the previous &struct rhash_head to continue from | |
396 | * @tbl: the &struct bucket_table | |
397 | * @hash: the hash value / bucket index | |
7e1e7763 | 398 | */ |
88d6ed15 TG |
399 | #define rht_for_each_continue(pos, head, tbl, hash) \ |
400 | for (pos = rht_dereference_bucket(head, tbl, hash); \ | |
f89bd6f8 | 401 | !rht_is_a_nulls(pos); \ |
88d6ed15 TG |
402 | pos = rht_dereference_bucket((pos)->next, tbl, hash)) |
403 | ||
404 | /** | |
405 | * rht_for_each - iterate over hash chain | |
406 | * @pos: the &struct rhash_head to use as a loop cursor. | |
407 | * @tbl: the &struct bucket_table | |
408 | * @hash: the hash value / bucket index | |
409 | */ | |
410 | #define rht_for_each(pos, tbl, hash) \ | |
411 | rht_for_each_continue(pos, (tbl)->buckets[hash], tbl, hash) | |
412 | ||
413 | /** | |
414 | * rht_for_each_entry_continue - continue iterating over hash chain | |
415 | * @tpos: the type * to use as a loop cursor. | |
416 | * @pos: the &struct rhash_head to use as a loop cursor. | |
417 | * @head: the previous &struct rhash_head to continue from | |
418 | * @tbl: the &struct bucket_table | |
419 | * @hash: the hash value / bucket index | |
420 | * @member: name of the &struct rhash_head within the hashable struct. | |
421 | */ | |
422 | #define rht_for_each_entry_continue(tpos, pos, head, tbl, hash, member) \ | |
423 | for (pos = rht_dereference_bucket(head, tbl, hash); \ | |
f89bd6f8 | 424 | (!rht_is_a_nulls(pos)) && rht_entry(tpos, pos, member); \ |
88d6ed15 | 425 | pos = rht_dereference_bucket((pos)->next, tbl, hash)) |
7e1e7763 TG |
426 | |
427 | /** | |
428 | * rht_for_each_entry - iterate over hash chain of given type | |
88d6ed15 TG |
429 | * @tpos: the type * to use as a loop cursor. |
430 | * @pos: the &struct rhash_head to use as a loop cursor. | |
431 | * @tbl: the &struct bucket_table | |
432 | * @hash: the hash value / bucket index | |
433 | * @member: name of the &struct rhash_head within the hashable struct. | |
7e1e7763 | 434 | */ |
88d6ed15 TG |
435 | #define rht_for_each_entry(tpos, pos, tbl, hash, member) \ |
436 | rht_for_each_entry_continue(tpos, pos, (tbl)->buckets[hash], \ | |
437 | tbl, hash, member) | |
7e1e7763 TG |
438 | |
439 | /** | |
440 | * rht_for_each_entry_safe - safely iterate over hash chain of given type | |
88d6ed15 TG |
441 | * @tpos: the type * to use as a loop cursor. |
442 | * @pos: the &struct rhash_head to use as a loop cursor. | |
443 | * @next: the &struct rhash_head to use as next in loop cursor. | |
444 | * @tbl: the &struct bucket_table | |
445 | * @hash: the hash value / bucket index | |
446 | * @member: name of the &struct rhash_head within the hashable struct. | |
7e1e7763 TG |
447 | * |
448 | * This hash chain list-traversal primitive allows for the looped code to | |
449 | * remove the loop cursor from the list. | |
450 | */ | |
88d6ed15 TG |
451 | #define rht_for_each_entry_safe(tpos, pos, next, tbl, hash, member) \ |
452 | for (pos = rht_dereference_bucket((tbl)->buckets[hash], tbl, hash), \ | |
f89bd6f8 TG |
453 | next = !rht_is_a_nulls(pos) ? \ |
454 | rht_dereference_bucket(pos->next, tbl, hash) : NULL; \ | |
455 | (!rht_is_a_nulls(pos)) && rht_entry(tpos, pos, member); \ | |
607954b0 PM |
456 | pos = next, \ |
457 | next = !rht_is_a_nulls(pos) ? \ | |
458 | rht_dereference_bucket(pos->next, tbl, hash) : NULL) | |
88d6ed15 TG |
459 | |
460 | /** | |
461 | * rht_for_each_rcu_continue - continue iterating over rcu hash chain | |
462 | * @pos: the &struct rhash_head to use as a loop cursor. | |
463 | * @head: the previous &struct rhash_head to continue from | |
464 | * @tbl: the &struct bucket_table | |
465 | * @hash: the hash value / bucket index | |
466 | * | |
467 | * This hash chain list-traversal primitive may safely run concurrently with | |
468 | * the _rcu mutation primitives such as rhashtable_insert() as long as the | |
469 | * traversal is guarded by rcu_read_lock(). | |
470 | */ | |
471 | #define rht_for_each_rcu_continue(pos, head, tbl, hash) \ | |
472 | for (({barrier(); }), \ | |
473 | pos = rht_dereference_bucket_rcu(head, tbl, hash); \ | |
f89bd6f8 | 474 | !rht_is_a_nulls(pos); \ |
88d6ed15 | 475 | pos = rcu_dereference_raw(pos->next)) |
7e1e7763 TG |
476 | |
477 | /** | |
478 | * rht_for_each_rcu - iterate over rcu hash chain | |
88d6ed15 TG |
479 | * @pos: the &struct rhash_head to use as a loop cursor. |
480 | * @tbl: the &struct bucket_table | |
481 | * @hash: the hash value / bucket index | |
7e1e7763 TG |
482 | * |
483 | * This hash chain list-traversal primitive may safely run concurrently with | |
88d6ed15 | 484 | * the _rcu mutation primitives such as rhashtable_insert() as long as the |
7e1e7763 TG |
485 | * traversal is guarded by rcu_read_lock(). |
486 | */ | |
88d6ed15 TG |
487 | #define rht_for_each_rcu(pos, tbl, hash) \ |
488 | rht_for_each_rcu_continue(pos, (tbl)->buckets[hash], tbl, hash) | |
489 | ||
490 | /** | |
491 | * rht_for_each_entry_rcu_continue - continue iterating over rcu hash chain | |
492 | * @tpos: the type * to use as a loop cursor. | |
493 | * @pos: the &struct rhash_head to use as a loop cursor. | |
494 | * @head: the previous &struct rhash_head to continue from | |
495 | * @tbl: the &struct bucket_table | |
496 | * @hash: the hash value / bucket index | |
497 | * @member: name of the &struct rhash_head within the hashable struct. | |
498 | * | |
499 | * This hash chain list-traversal primitive may safely run concurrently with | |
500 | * the _rcu mutation primitives such as rhashtable_insert() as long as the | |
501 | * traversal is guarded by rcu_read_lock(). | |
502 | */ | |
503 | #define rht_for_each_entry_rcu_continue(tpos, pos, head, tbl, hash, member) \ | |
504 | for (({barrier(); }), \ | |
505 | pos = rht_dereference_bucket_rcu(head, tbl, hash); \ | |
f89bd6f8 | 506 | (!rht_is_a_nulls(pos)) && rht_entry(tpos, pos, member); \ |
88d6ed15 | 507 | pos = rht_dereference_bucket_rcu(pos->next, tbl, hash)) |
7e1e7763 TG |
508 | |
509 | /** | |
510 | * rht_for_each_entry_rcu - iterate over rcu hash chain of given type | |
88d6ed15 TG |
511 | * @tpos: the type * to use as a loop cursor. |
512 | * @pos: the &struct rhash_head to use as a loop cursor. | |
513 | * @tbl: the &struct bucket_table | |
514 | * @hash: the hash value / bucket index | |
515 | * @member: name of the &struct rhash_head within the hashable struct. | |
7e1e7763 TG |
516 | * |
517 | * This hash chain list-traversal primitive may safely run concurrently with | |
88d6ed15 | 518 | * the _rcu mutation primitives such as rhashtable_insert() as long as the |
7e1e7763 TG |
519 | * traversal is guarded by rcu_read_lock(). |
520 | */ | |
88d6ed15 TG |
521 | #define rht_for_each_entry_rcu(tpos, pos, tbl, hash, member) \ |
522 | rht_for_each_entry_rcu_continue(tpos, pos, (tbl)->buckets[hash],\ | |
523 | tbl, hash, member) | |
7e1e7763 | 524 | |
ca26893f HX |
525 | /** |
526 | * rhl_for_each_rcu - iterate over rcu hash table list | |
527 | * @pos: the &struct rlist_head to use as a loop cursor. | |
528 | * @list: the head of the list | |
529 | * | |
530 | * This hash chain list-traversal primitive should be used on the | |
531 | * list returned by rhltable_lookup. | |
532 | */ | |
533 | #define rhl_for_each_rcu(pos, list) \ | |
534 | for (pos = list; pos; pos = rcu_dereference_raw(pos->next)) | |
535 | ||
536 | /** | |
537 | * rhl_for_each_entry_rcu - iterate over rcu hash table list of given type | |
538 | * @tpos: the type * to use as a loop cursor. | |
539 | * @pos: the &struct rlist_head to use as a loop cursor. | |
540 | * @list: the head of the list | |
541 | * @member: name of the &struct rlist_head within the hashable struct. | |
542 | * | |
543 | * This hash chain list-traversal primitive should be used on the | |
544 | * list returned by rhltable_lookup. | |
545 | */ | |
546 | #define rhl_for_each_entry_rcu(tpos, pos, list, member) \ | |
547 | for (pos = list; pos && rht_entry(tpos, pos, member); \ | |
548 | pos = rcu_dereference_raw(pos->next)) | |
549 | ||
02fd97c3 HX |
550 | static inline int rhashtable_compare(struct rhashtable_compare_arg *arg, |
551 | const void *obj) | |
552 | { | |
553 | struct rhashtable *ht = arg->ht; | |
554 | const char *ptr = obj; | |
555 | ||
556 | return memcmp(ptr + ht->p.key_offset, arg->key, ht->p.key_len); | |
557 | } | |
558 | ||
ca26893f HX |
559 | /* Internal function, do not use. */ |
560 | static inline struct rhash_head *__rhashtable_lookup( | |
02fd97c3 HX |
561 | struct rhashtable *ht, const void *key, |
562 | const struct rhashtable_params params) | |
563 | { | |
564 | struct rhashtable_compare_arg arg = { | |
565 | .ht = ht, | |
566 | .key = key, | |
567 | }; | |
568 | const struct bucket_table *tbl; | |
569 | struct rhash_head *he; | |
299e5c32 | 570 | unsigned int hash; |
02fd97c3 | 571 | |
02fd97c3 HX |
572 | tbl = rht_dereference_rcu(ht->tbl, ht); |
573 | restart: | |
574 | hash = rht_key_hashfn(ht, tbl, key, params); | |
575 | rht_for_each_rcu(he, tbl, hash) { | |
576 | if (params.obj_cmpfn ? | |
577 | params.obj_cmpfn(&arg, rht_obj(ht, he)) : | |
578 | rhashtable_compare(&arg, rht_obj(ht, he))) | |
579 | continue; | |
ca26893f | 580 | return he; |
02fd97c3 HX |
581 | } |
582 | ||
583 | /* Ensure we see any new tables. */ | |
584 | smp_rmb(); | |
585 | ||
586 | tbl = rht_dereference_rcu(tbl->future_tbl, ht); | |
587 | if (unlikely(tbl)) | |
588 | goto restart; | |
02fd97c3 HX |
589 | |
590 | return NULL; | |
591 | } | |
592 | ||
ca26893f HX |
593 | /** |
594 | * rhashtable_lookup - search hash table | |
595 | * @ht: hash table | |
596 | * @key: the pointer to the key | |
597 | * @params: hash table parameters | |
598 | * | |
599 | * Computes the hash value for the key and traverses the bucket chain looking | |
600 | * for a entry with an identical key. The first matching entry is returned. | |
601 | * | |
602 | * This must only be called under the RCU read lock. | |
603 | * | |
604 | * Returns the first entry on which the compare function returned true. | |
605 | */ | |
606 | static inline void *rhashtable_lookup( | |
607 | struct rhashtable *ht, const void *key, | |
608 | const struct rhashtable_params params) | |
609 | { | |
610 | struct rhash_head *he = __rhashtable_lookup(ht, key, params); | |
611 | ||
612 | return he ? rht_obj(ht, he) : NULL; | |
613 | } | |
614 | ||
615 | /** | |
616 | * rhashtable_lookup_fast - search hash table, without RCU read lock | |
617 | * @ht: hash table | |
618 | * @key: the pointer to the key | |
619 | * @params: hash table parameters | |
620 | * | |
621 | * Computes the hash value for the key and traverses the bucket chain looking | |
622 | * for a entry with an identical key. The first matching entry is returned. | |
623 | * | |
624 | * Only use this function when you have other mechanisms guaranteeing | |
625 | * that the object won't go away after the RCU read lock is released. | |
626 | * | |
627 | * Returns the first entry on which the compare function returned true. | |
628 | */ | |
629 | static inline void *rhashtable_lookup_fast( | |
630 | struct rhashtable *ht, const void *key, | |
631 | const struct rhashtable_params params) | |
632 | { | |
633 | void *obj; | |
634 | ||
635 | rcu_read_lock(); | |
636 | obj = rhashtable_lookup(ht, key, params); | |
637 | rcu_read_unlock(); | |
638 | ||
639 | return obj; | |
640 | } | |
641 | ||
642 | /** | |
643 | * rhltable_lookup - search hash list table | |
644 | * @hlt: hash table | |
645 | * @key: the pointer to the key | |
646 | * @params: hash table parameters | |
647 | * | |
648 | * Computes the hash value for the key and traverses the bucket chain looking | |
649 | * for a entry with an identical key. All matching entries are returned | |
650 | * in a list. | |
651 | * | |
652 | * This must only be called under the RCU read lock. | |
653 | * | |
654 | * Returns the list of entries that match the given key. | |
655 | */ | |
656 | static inline struct rhlist_head *rhltable_lookup( | |
657 | struct rhltable *hlt, const void *key, | |
658 | const struct rhashtable_params params) | |
659 | { | |
660 | struct rhash_head *he = __rhashtable_lookup(&hlt->ht, key, params); | |
661 | ||
662 | return he ? container_of(he, struct rhlist_head, rhead) : NULL; | |
663 | } | |
664 | ||
5ca8cc5b PNA |
665 | /* Internal function, please use rhashtable_insert_fast() instead. This |
666 | * function returns the existing element already in hashes in there is a clash, | |
667 | * otherwise it returns an error via ERR_PTR(). | |
668 | */ | |
669 | static inline void *__rhashtable_insert_fast( | |
02fd97c3 | 670 | struct rhashtable *ht, const void *key, struct rhash_head *obj, |
ca26893f | 671 | const struct rhashtable_params params, bool rhlist) |
02fd97c3 HX |
672 | { |
673 | struct rhashtable_compare_arg arg = { | |
674 | .ht = ht, | |
675 | .key = key, | |
676 | }; | |
ca26893f HX |
677 | struct rhash_head __rcu **pprev; |
678 | struct bucket_table *tbl; | |
02fd97c3 HX |
679 | struct rhash_head *head; |
680 | spinlock_t *lock; | |
299e5c32 | 681 | unsigned int hash; |
ca26893f HX |
682 | int elasticity; |
683 | void *data; | |
02fd97c3 HX |
684 | |
685 | rcu_read_lock(); | |
686 | ||
687 | tbl = rht_dereference_rcu(ht->tbl, ht); | |
ca26893f HX |
688 | hash = rht_head_hashfn(ht, tbl, obj, params); |
689 | lock = rht_bucket_lock(tbl, hash); | |
690 | spin_lock_bh(lock); | |
02fd97c3 | 691 | |
ca26893f HX |
692 | if (unlikely(rht_dereference_bucket(tbl->future_tbl, tbl, hash))) { |
693 | slow_path: | |
b824478b | 694 | spin_unlock_bh(lock); |
ca26893f HX |
695 | rcu_read_unlock(); |
696 | return rhashtable_insert_slow(ht, key, obj); | |
b824478b HX |
697 | } |
698 | ||
ca26893f HX |
699 | elasticity = ht->elasticity; |
700 | pprev = &tbl->buckets[hash]; | |
701 | rht_for_each(head, tbl, hash) { | |
702 | struct rhlist_head *plist; | |
703 | struct rhlist_head *list; | |
704 | ||
705 | elasticity--; | |
706 | if (!key || | |
707 | (params.obj_cmpfn ? | |
708 | params.obj_cmpfn(&arg, rht_obj(ht, head)) : | |
709 | rhashtable_compare(&arg, rht_obj(ht, head)))) | |
710 | continue; | |
711 | ||
712 | data = rht_obj(ht, head); | |
3cf92222 | 713 | |
ca26893f HX |
714 | if (!rhlist) |
715 | goto out; | |
5ca8cc5b | 716 | |
02fd97c3 | 717 | |
ca26893f HX |
718 | list = container_of(obj, struct rhlist_head, rhead); |
719 | plist = container_of(head, struct rhlist_head, rhead); | |
07ee0722 | 720 | |
ca26893f HX |
721 | RCU_INIT_POINTER(list->next, plist); |
722 | head = rht_dereference_bucket(head->next, tbl, hash); | |
723 | RCU_INIT_POINTER(list->rhead.next, head); | |
724 | rcu_assign_pointer(*pprev, obj); | |
ccd57b1b | 725 | |
ca26893f | 726 | goto good; |
ccd57b1b | 727 | } |
02fd97c3 | 728 | |
ca26893f HX |
729 | if (elasticity <= 0) |
730 | goto slow_path; | |
731 | ||
732 | data = ERR_PTR(-E2BIG); | |
733 | if (unlikely(rht_grow_above_max(ht, tbl))) | |
734 | goto out; | |
735 | ||
736 | if (unlikely(rht_grow_above_100(ht, tbl))) | |
737 | goto slow_path; | |
02fd97c3 | 738 | |
02fd97c3 HX |
739 | head = rht_dereference_bucket(tbl->buckets[hash], tbl, hash); |
740 | ||
741 | RCU_INIT_POINTER(obj->next, head); | |
ca26893f HX |
742 | if (rhlist) { |
743 | struct rhlist_head *list; | |
744 | ||
745 | list = container_of(obj, struct rhlist_head, rhead); | |
746 | RCU_INIT_POINTER(list->next, NULL); | |
747 | } | |
02fd97c3 HX |
748 | |
749 | rcu_assign_pointer(tbl->buckets[hash], obj); | |
750 | ||
751 | atomic_inc(&ht->nelems); | |
752 | if (rht_grow_above_75(ht, tbl)) | |
753 | schedule_work(&ht->run_work); | |
754 | ||
ca26893f HX |
755 | good: |
756 | data = NULL; | |
757 | ||
02fd97c3 HX |
758 | out: |
759 | spin_unlock_bh(lock); | |
760 | rcu_read_unlock(); | |
761 | ||
ca26893f | 762 | return data; |
02fd97c3 HX |
763 | } |
764 | ||
765 | /** | |
766 | * rhashtable_insert_fast - insert object into hash table | |
767 | * @ht: hash table | |
768 | * @obj: pointer to hash head inside object | |
769 | * @params: hash table parameters | |
770 | * | |
771 | * Will take a per bucket spinlock to protect against mutual mutations | |
772 | * on the same bucket. Multiple insertions may occur in parallel unless | |
773 | * they map to the same bucket lock. | |
774 | * | |
775 | * It is safe to call this function from atomic context. | |
776 | * | |
777 | * Will trigger an automatic deferred table resizing if the size grows | |
778 | * beyond the watermark indicated by grow_decision() which can be passed | |
779 | * to rhashtable_init(). | |
780 | */ | |
781 | static inline int rhashtable_insert_fast( | |
782 | struct rhashtable *ht, struct rhash_head *obj, | |
783 | const struct rhashtable_params params) | |
784 | { | |
5ca8cc5b PNA |
785 | void *ret; |
786 | ||
ca26893f | 787 | ret = __rhashtable_insert_fast(ht, NULL, obj, params, false); |
5ca8cc5b PNA |
788 | if (IS_ERR(ret)) |
789 | return PTR_ERR(ret); | |
790 | ||
791 | return ret == NULL ? 0 : -EEXIST; | |
02fd97c3 HX |
792 | } |
793 | ||
ca26893f HX |
794 | /** |
795 | * rhltable_insert_key - insert object into hash list table | |
796 | * @hlt: hash list table | |
797 | * @key: the pointer to the key | |
798 | * @list: pointer to hash list head inside object | |
799 | * @params: hash table parameters | |
800 | * | |
801 | * Will take a per bucket spinlock to protect against mutual mutations | |
802 | * on the same bucket. Multiple insertions may occur in parallel unless | |
803 | * they map to the same bucket lock. | |
804 | * | |
805 | * It is safe to call this function from atomic context. | |
806 | * | |
807 | * Will trigger an automatic deferred table resizing if the size grows | |
808 | * beyond the watermark indicated by grow_decision() which can be passed | |
809 | * to rhashtable_init(). | |
810 | */ | |
811 | static inline int rhltable_insert_key( | |
812 | struct rhltable *hlt, const void *key, struct rhlist_head *list, | |
813 | const struct rhashtable_params params) | |
814 | { | |
815 | return PTR_ERR(__rhashtable_insert_fast(&hlt->ht, key, &list->rhead, | |
816 | params, true)); | |
817 | } | |
818 | ||
819 | /** | |
820 | * rhltable_insert - insert object into hash list table | |
821 | * @hlt: hash list table | |
822 | * @list: pointer to hash list head inside object | |
823 | * @params: hash table parameters | |
824 | * | |
825 | * Will take a per bucket spinlock to protect against mutual mutations | |
826 | * on the same bucket. Multiple insertions may occur in parallel unless | |
827 | * they map to the same bucket lock. | |
828 | * | |
829 | * It is safe to call this function from atomic context. | |
830 | * | |
831 | * Will trigger an automatic deferred table resizing if the size grows | |
832 | * beyond the watermark indicated by grow_decision() which can be passed | |
833 | * to rhashtable_init(). | |
834 | */ | |
835 | static inline int rhltable_insert( | |
836 | struct rhltable *hlt, struct rhlist_head *list, | |
837 | const struct rhashtable_params params) | |
838 | { | |
839 | const char *key = rht_obj(&hlt->ht, &list->rhead); | |
840 | ||
841 | key += params.key_offset; | |
842 | ||
843 | return rhltable_insert_key(hlt, key, list, params); | |
844 | } | |
845 | ||
02fd97c3 HX |
846 | /** |
847 | * rhashtable_lookup_insert_fast - lookup and insert object into hash table | |
848 | * @ht: hash table | |
849 | * @obj: pointer to hash head inside object | |
850 | * @params: hash table parameters | |
851 | * | |
852 | * Locks down the bucket chain in both the old and new table if a resize | |
853 | * is in progress to ensure that writers can't remove from the old table | |
854 | * and can't insert to the new table during the atomic operation of search | |
855 | * and insertion. Searches for duplicates in both the old and new table if | |
856 | * a resize is in progress. | |
857 | * | |
858 | * This lookup function may only be used for fixed key hash table (key_len | |
859 | * parameter set). It will BUG() if used inappropriately. | |
860 | * | |
861 | * It is safe to call this function from atomic context. | |
862 | * | |
863 | * Will trigger an automatic deferred table resizing if the size grows | |
864 | * beyond the watermark indicated by grow_decision() which can be passed | |
865 | * to rhashtable_init(). | |
866 | */ | |
867 | static inline int rhashtable_lookup_insert_fast( | |
868 | struct rhashtable *ht, struct rhash_head *obj, | |
869 | const struct rhashtable_params params) | |
870 | { | |
871 | const char *key = rht_obj(ht, obj); | |
5ca8cc5b | 872 | void *ret; |
02fd97c3 HX |
873 | |
874 | BUG_ON(ht->p.obj_hashfn); | |
875 | ||
ca26893f HX |
876 | ret = __rhashtable_insert_fast(ht, key + ht->p.key_offset, obj, params, |
877 | false); | |
5ca8cc5b PNA |
878 | if (IS_ERR(ret)) |
879 | return PTR_ERR(ret); | |
880 | ||
881 | return ret == NULL ? 0 : -EEXIST; | |
02fd97c3 HX |
882 | } |
883 | ||
884 | /** | |
885 | * rhashtable_lookup_insert_key - search and insert object to hash table | |
886 | * with explicit key | |
887 | * @ht: hash table | |
888 | * @key: key | |
889 | * @obj: pointer to hash head inside object | |
890 | * @params: hash table parameters | |
891 | * | |
892 | * Locks down the bucket chain in both the old and new table if a resize | |
893 | * is in progress to ensure that writers can't remove from the old table | |
894 | * and can't insert to the new table during the atomic operation of search | |
895 | * and insertion. Searches for duplicates in both the old and new table if | |
896 | * a resize is in progress. | |
897 | * | |
898 | * Lookups may occur in parallel with hashtable mutations and resizing. | |
899 | * | |
900 | * Will trigger an automatic deferred table resizing if the size grows | |
901 | * beyond the watermark indicated by grow_decision() which can be passed | |
902 | * to rhashtable_init(). | |
903 | * | |
904 | * Returns zero on success. | |
905 | */ | |
906 | static inline int rhashtable_lookup_insert_key( | |
907 | struct rhashtable *ht, const void *key, struct rhash_head *obj, | |
908 | const struct rhashtable_params params) | |
5ca8cc5b PNA |
909 | { |
910 | void *ret; | |
911 | ||
912 | BUG_ON(!ht->p.obj_hashfn || !key); | |
913 | ||
ca26893f | 914 | ret = __rhashtable_insert_fast(ht, key, obj, params, false); |
5ca8cc5b PNA |
915 | if (IS_ERR(ret)) |
916 | return PTR_ERR(ret); | |
917 | ||
918 | return ret == NULL ? 0 : -EEXIST; | |
919 | } | |
920 | ||
921 | /** | |
922 | * rhashtable_lookup_get_insert_key - lookup and insert object into hash table | |
923 | * @ht: hash table | |
924 | * @obj: pointer to hash head inside object | |
925 | * @params: hash table parameters | |
926 | * @data: pointer to element data already in hashes | |
927 | * | |
928 | * Just like rhashtable_lookup_insert_key(), but this function returns the | |
929 | * object if it exists, NULL if it does not and the insertion was successful, | |
930 | * and an ERR_PTR otherwise. | |
931 | */ | |
932 | static inline void *rhashtable_lookup_get_insert_key( | |
933 | struct rhashtable *ht, const void *key, struct rhash_head *obj, | |
934 | const struct rhashtable_params params) | |
02fd97c3 HX |
935 | { |
936 | BUG_ON(!ht->p.obj_hashfn || !key); | |
937 | ||
ca26893f | 938 | return __rhashtable_insert_fast(ht, key, obj, params, false); |
02fd97c3 HX |
939 | } |
940 | ||
ac833bdd | 941 | /* Internal function, please use rhashtable_remove_fast() instead */ |
ca26893f | 942 | static inline int __rhashtable_remove_fast_one( |
02fd97c3 | 943 | struct rhashtable *ht, struct bucket_table *tbl, |
ca26893f HX |
944 | struct rhash_head *obj, const struct rhashtable_params params, |
945 | bool rhlist) | |
02fd97c3 HX |
946 | { |
947 | struct rhash_head __rcu **pprev; | |
948 | struct rhash_head *he; | |
949 | spinlock_t * lock; | |
299e5c32 | 950 | unsigned int hash; |
02fd97c3 HX |
951 | int err = -ENOENT; |
952 | ||
953 | hash = rht_head_hashfn(ht, tbl, obj, params); | |
954 | lock = rht_bucket_lock(tbl, hash); | |
955 | ||
956 | spin_lock_bh(lock); | |
957 | ||
958 | pprev = &tbl->buckets[hash]; | |
959 | rht_for_each(he, tbl, hash) { | |
ca26893f HX |
960 | struct rhlist_head *list; |
961 | ||
962 | list = container_of(he, struct rhlist_head, rhead); | |
963 | ||
02fd97c3 | 964 | if (he != obj) { |
ca26893f HX |
965 | struct rhlist_head __rcu **lpprev; |
966 | ||
02fd97c3 | 967 | pprev = &he->next; |
ca26893f HX |
968 | |
969 | if (!rhlist) | |
970 | continue; | |
971 | ||
972 | do { | |
973 | lpprev = &list->next; | |
974 | list = rht_dereference_bucket(list->next, | |
975 | tbl, hash); | |
976 | } while (list && obj != &list->rhead); | |
977 | ||
978 | if (!list) | |
979 | continue; | |
980 | ||
981 | list = rht_dereference_bucket(list->next, tbl, hash); | |
982 | RCU_INIT_POINTER(*lpprev, list); | |
983 | err = 0; | |
984 | break; | |
02fd97c3 HX |
985 | } |
986 | ||
ca26893f HX |
987 | obj = rht_dereference_bucket(obj->next, tbl, hash); |
988 | err = 1; | |
989 | ||
990 | if (rhlist) { | |
991 | list = rht_dereference_bucket(list->next, tbl, hash); | |
992 | if (list) { | |
993 | RCU_INIT_POINTER(list->rhead.next, obj); | |
994 | obj = &list->rhead; | |
995 | err = 0; | |
996 | } | |
997 | } | |
998 | ||
999 | rcu_assign_pointer(*pprev, obj); | |
02fd97c3 HX |
1000 | break; |
1001 | } | |
1002 | ||
1003 | spin_unlock_bh(lock); | |
1004 | ||
ca26893f HX |
1005 | if (err > 0) { |
1006 | atomic_dec(&ht->nelems); | |
1007 | if (unlikely(ht->p.automatic_shrinking && | |
1008 | rht_shrink_below_30(ht, tbl))) | |
1009 | schedule_work(&ht->run_work); | |
1010 | err = 0; | |
1011 | } | |
1012 | ||
02fd97c3 HX |
1013 | return err; |
1014 | } | |
1015 | ||
ca26893f HX |
1016 | /* Internal function, please use rhashtable_remove_fast() instead */ |
1017 | static inline int __rhashtable_remove_fast( | |
02fd97c3 | 1018 | struct rhashtable *ht, struct rhash_head *obj, |
ca26893f | 1019 | const struct rhashtable_params params, bool rhlist) |
02fd97c3 HX |
1020 | { |
1021 | struct bucket_table *tbl; | |
1022 | int err; | |
1023 | ||
1024 | rcu_read_lock(); | |
1025 | ||
1026 | tbl = rht_dereference_rcu(ht->tbl, ht); | |
1027 | ||
1028 | /* Because we have already taken (and released) the bucket | |
1029 | * lock in old_tbl, if we find that future_tbl is not yet | |
1030 | * visible then that guarantees the entry to still be in | |
1031 | * the old tbl if it exists. | |
1032 | */ | |
ca26893f HX |
1033 | while ((err = __rhashtable_remove_fast_one(ht, tbl, obj, params, |
1034 | rhlist)) && | |
02fd97c3 HX |
1035 | (tbl = rht_dereference_rcu(tbl->future_tbl, ht))) |
1036 | ; | |
1037 | ||
02fd97c3 HX |
1038 | rcu_read_unlock(); |
1039 | ||
1040 | return err; | |
1041 | } | |
1042 | ||
ca26893f HX |
1043 | /** |
1044 | * rhashtable_remove_fast - remove object from hash table | |
1045 | * @ht: hash table | |
1046 | * @obj: pointer to hash head inside object | |
1047 | * @params: hash table parameters | |
1048 | * | |
1049 | * Since the hash chain is single linked, the removal operation needs to | |
1050 | * walk the bucket chain upon removal. The removal operation is thus | |
1051 | * considerable slow if the hash table is not correctly sized. | |
1052 | * | |
1053 | * Will automatically shrink the table via rhashtable_expand() if the | |
1054 | * shrink_decision function specified at rhashtable_init() returns true. | |
1055 | * | |
1056 | * Returns zero on success, -ENOENT if the entry could not be found. | |
1057 | */ | |
1058 | static inline int rhashtable_remove_fast( | |
1059 | struct rhashtable *ht, struct rhash_head *obj, | |
1060 | const struct rhashtable_params params) | |
1061 | { | |
1062 | return __rhashtable_remove_fast(ht, obj, params, false); | |
1063 | } | |
1064 | ||
1065 | /** | |
1066 | * rhltable_remove - remove object from hash list table | |
1067 | * @hlt: hash list table | |
1068 | * @list: pointer to hash list head inside object | |
1069 | * @params: hash table parameters | |
1070 | * | |
1071 | * Since the hash chain is single linked, the removal operation needs to | |
1072 | * walk the bucket chain upon removal. The removal operation is thus | |
1073 | * considerable slow if the hash table is not correctly sized. | |
1074 | * | |
1075 | * Will automatically shrink the table via rhashtable_expand() if the | |
1076 | * shrink_decision function specified at rhashtable_init() returns true. | |
1077 | * | |
1078 | * Returns zero on success, -ENOENT if the entry could not be found. | |
1079 | */ | |
1080 | static inline int rhltable_remove( | |
1081 | struct rhltable *hlt, struct rhlist_head *list, | |
1082 | const struct rhashtable_params params) | |
1083 | { | |
1084 | return __rhashtable_remove_fast(&hlt->ht, &list->rhead, params, true); | |
1085 | } | |
1086 | ||
3502cad7 TH |
1087 | /* Internal function, please use rhashtable_replace_fast() instead */ |
1088 | static inline int __rhashtable_replace_fast( | |
1089 | struct rhashtable *ht, struct bucket_table *tbl, | |
1090 | struct rhash_head *obj_old, struct rhash_head *obj_new, | |
1091 | const struct rhashtable_params params) | |
1092 | { | |
1093 | struct rhash_head __rcu **pprev; | |
1094 | struct rhash_head *he; | |
1095 | spinlock_t *lock; | |
1096 | unsigned int hash; | |
1097 | int err = -ENOENT; | |
1098 | ||
1099 | /* Minimally, the old and new objects must have same hash | |
1100 | * (which should mean identifiers are the same). | |
1101 | */ | |
1102 | hash = rht_head_hashfn(ht, tbl, obj_old, params); | |
1103 | if (hash != rht_head_hashfn(ht, tbl, obj_new, params)) | |
1104 | return -EINVAL; | |
1105 | ||
1106 | lock = rht_bucket_lock(tbl, hash); | |
1107 | ||
1108 | spin_lock_bh(lock); | |
1109 | ||
1110 | pprev = &tbl->buckets[hash]; | |
1111 | rht_for_each(he, tbl, hash) { | |
1112 | if (he != obj_old) { | |
1113 | pprev = &he->next; | |
1114 | continue; | |
1115 | } | |
1116 | ||
1117 | rcu_assign_pointer(obj_new->next, obj_old->next); | |
1118 | rcu_assign_pointer(*pprev, obj_new); | |
1119 | err = 0; | |
1120 | break; | |
1121 | } | |
1122 | ||
1123 | spin_unlock_bh(lock); | |
1124 | ||
1125 | return err; | |
1126 | } | |
1127 | ||
1128 | /** | |
1129 | * rhashtable_replace_fast - replace an object in hash table | |
1130 | * @ht: hash table | |
1131 | * @obj_old: pointer to hash head inside object being replaced | |
1132 | * @obj_new: pointer to hash head inside object which is new | |
1133 | * @params: hash table parameters | |
1134 | * | |
1135 | * Replacing an object doesn't affect the number of elements in the hash table | |
1136 | * or bucket, so we don't need to worry about shrinking or expanding the | |
1137 | * table here. | |
1138 | * | |
1139 | * Returns zero on success, -ENOENT if the entry could not be found, | |
1140 | * -EINVAL if hash is not the same for the old and new objects. | |
1141 | */ | |
1142 | static inline int rhashtable_replace_fast( | |
1143 | struct rhashtable *ht, struct rhash_head *obj_old, | |
1144 | struct rhash_head *obj_new, | |
1145 | const struct rhashtable_params params) | |
1146 | { | |
1147 | struct bucket_table *tbl; | |
1148 | int err; | |
1149 | ||
1150 | rcu_read_lock(); | |
1151 | ||
1152 | tbl = rht_dereference_rcu(ht->tbl, ht); | |
1153 | ||
1154 | /* Because we have already taken (and released) the bucket | |
1155 | * lock in old_tbl, if we find that future_tbl is not yet | |
1156 | * visible then that guarantees the entry to still be in | |
1157 | * the old tbl if it exists. | |
1158 | */ | |
1159 | while ((err = __rhashtable_replace_fast(ht, tbl, obj_old, | |
1160 | obj_new, params)) && | |
1161 | (tbl = rht_dereference_rcu(tbl->future_tbl, ht))) | |
1162 | ; | |
1163 | ||
1164 | rcu_read_unlock(); | |
1165 | ||
1166 | return err; | |
1167 | } | |
1168 | ||
246779dd HX |
1169 | /* Obsolete function, do not use in new code. */ |
1170 | static inline int rhashtable_walk_init(struct rhashtable *ht, | |
1171 | struct rhashtable_iter *iter, gfp_t gfp) | |
1172 | { | |
1173 | rhashtable_walk_enter(ht, iter); | |
1174 | return 0; | |
1175 | } | |
1176 | ||
ca26893f HX |
1177 | /** |
1178 | * rhltable_walk_enter - Initialise an iterator | |
1179 | * @hlt: Table to walk over | |
1180 | * @iter: Hash table Iterator | |
1181 | * | |
1182 | * This function prepares a hash table walk. | |
1183 | * | |
1184 | * Note that if you restart a walk after rhashtable_walk_stop you | |
1185 | * may see the same object twice. Also, you may miss objects if | |
1186 | * there are removals in between rhashtable_walk_stop and the next | |
1187 | * call to rhashtable_walk_start. | |
1188 | * | |
1189 | * For a completely stable walk you should construct your own data | |
1190 | * structure outside the hash table. | |
1191 | * | |
1192 | * This function may sleep so you must not call it from interrupt | |
1193 | * context or with spin locks held. | |
1194 | * | |
1195 | * You must call rhashtable_walk_exit after this function returns. | |
1196 | */ | |
1197 | static inline void rhltable_walk_enter(struct rhltable *hlt, | |
1198 | struct rhashtable_iter *iter) | |
1199 | { | |
1200 | return rhashtable_walk_enter(&hlt->ht, iter); | |
1201 | } | |
1202 | ||
1203 | /** | |
1204 | * rhltable_free_and_destroy - free elements and destroy hash list table | |
1205 | * @hlt: the hash list table to destroy | |
1206 | * @free_fn: callback to release resources of element | |
1207 | * @arg: pointer passed to free_fn | |
1208 | * | |
1209 | * See documentation for rhashtable_free_and_destroy. | |
1210 | */ | |
1211 | static inline void rhltable_free_and_destroy(struct rhltable *hlt, | |
1212 | void (*free_fn)(void *ptr, | |
1213 | void *arg), | |
1214 | void *arg) | |
1215 | { | |
1216 | return rhashtable_free_and_destroy(&hlt->ht, free_fn, arg); | |
1217 | } | |
1218 | ||
1219 | static inline void rhltable_destroy(struct rhltable *hlt) | |
1220 | { | |
1221 | return rhltable_free_and_destroy(hlt, NULL, NULL); | |
1222 | } | |
1223 | ||
7e1e7763 | 1224 | #endif /* _LINUX_RHASHTABLE_H */ |