]>
Commit | Line | Data |
---|---|---|
1 | // SPDX-License-Identifier: GPL-2.0-only | |
2 | /* | |
3 | * Resizable, Scalable, Concurrent Hash Table | |
4 | * | |
5 | * Copyright (c) 2015 Herbert Xu <herbert@gondor.apana.org.au> | |
6 | * Copyright (c) 2014-2015 Thomas Graf <tgraf@suug.ch> | |
7 | * Copyright (c) 2008-2014 Patrick McHardy <kaber@trash.net> | |
8 | * | |
9 | * Code partially derived from nft_hash | |
10 | * Rewritten with rehash code from br_multicast plus single list | |
11 | * pointer as suggested by Josh Triplett | |
12 | */ | |
13 | ||
14 | #include <linux/atomic.h> | |
15 | #include <linux/kernel.h> | |
16 | #include <linux/init.h> | |
17 | #include <linux/log2.h> | |
18 | #include <linux/sched.h> | |
19 | #include <linux/rculist.h> | |
20 | #include <linux/slab.h> | |
21 | #include <linux/vmalloc.h> | |
22 | #include <linux/mm.h> | |
23 | #include <linux/jhash.h> | |
24 | #include <linux/random.h> | |
25 | #include <linux/rhashtable.h> | |
26 | #include <linux/err.h> | |
27 | #include <linux/export.h> | |
28 | ||
29 | #define HASH_DEFAULT_SIZE 64UL | |
30 | #define HASH_MIN_SIZE 4U | |
31 | ||
32 | union nested_table { | |
33 | union nested_table __rcu *table; | |
34 | struct rhash_lock_head *bucket; | |
35 | }; | |
36 | ||
37 | static u32 head_hashfn(struct rhashtable *ht, | |
38 | const struct bucket_table *tbl, | |
39 | const struct rhash_head *he) | |
40 | { | |
41 | return rht_head_hashfn(ht, tbl, he, ht->p); | |
42 | } | |
43 | ||
44 | #ifdef CONFIG_PROVE_LOCKING | |
45 | #define ASSERT_RHT_MUTEX(HT) BUG_ON(!lockdep_rht_mutex_is_held(HT)) | |
46 | ||
47 | int lockdep_rht_mutex_is_held(struct rhashtable *ht) | |
48 | { | |
49 | return (debug_locks) ? lockdep_is_held(&ht->mutex) : 1; | |
50 | } | |
51 | EXPORT_SYMBOL_GPL(lockdep_rht_mutex_is_held); | |
52 | ||
53 | int lockdep_rht_bucket_is_held(const struct bucket_table *tbl, u32 hash) | |
54 | { | |
55 | if (!debug_locks) | |
56 | return 1; | |
57 | if (unlikely(tbl->nest)) | |
58 | return 1; | |
59 | return bit_spin_is_locked(0, (unsigned long *)&tbl->buckets[hash]); | |
60 | } | |
61 | EXPORT_SYMBOL_GPL(lockdep_rht_bucket_is_held); | |
62 | #else | |
63 | #define ASSERT_RHT_MUTEX(HT) | |
64 | #endif | |
65 | ||
66 | static void nested_table_free(union nested_table *ntbl, unsigned int size) | |
67 | { | |
68 | const unsigned int shift = PAGE_SHIFT - ilog2(sizeof(void *)); | |
69 | const unsigned int len = 1 << shift; | |
70 | unsigned int i; | |
71 | ||
72 | ntbl = rcu_dereference_raw(ntbl->table); | |
73 | if (!ntbl) | |
74 | return; | |
75 | ||
76 | if (size > len) { | |
77 | size >>= shift; | |
78 | for (i = 0; i < len; i++) | |
79 | nested_table_free(ntbl + i, size); | |
80 | } | |
81 | ||
82 | kfree(ntbl); | |
83 | } | |
84 | ||
85 | static void nested_bucket_table_free(const struct bucket_table *tbl) | |
86 | { | |
87 | unsigned int size = tbl->size >> tbl->nest; | |
88 | unsigned int len = 1 << tbl->nest; | |
89 | union nested_table *ntbl; | |
90 | unsigned int i; | |
91 | ||
92 | ntbl = (union nested_table *)rcu_dereference_raw(tbl->buckets[0]); | |
93 | ||
94 | for (i = 0; i < len; i++) | |
95 | nested_table_free(ntbl + i, size); | |
96 | ||
97 | kfree(ntbl); | |
98 | } | |
99 | ||
100 | static void bucket_table_free(const struct bucket_table *tbl) | |
101 | { | |
102 | if (tbl->nest) | |
103 | nested_bucket_table_free(tbl); | |
104 | ||
105 | kvfree(tbl); | |
106 | } | |
107 | ||
108 | static void bucket_table_free_rcu(struct rcu_head *head) | |
109 | { | |
110 | bucket_table_free(container_of(head, struct bucket_table, rcu)); | |
111 | } | |
112 | ||
113 | static union nested_table *nested_table_alloc(struct rhashtable *ht, | |
114 | union nested_table __rcu **prev, | |
115 | bool leaf) | |
116 | { | |
117 | union nested_table *ntbl; | |
118 | int i; | |
119 | ||
120 | ntbl = rcu_dereference(*prev); | |
121 | if (ntbl) | |
122 | return ntbl; | |
123 | ||
124 | ntbl = kzalloc(PAGE_SIZE, GFP_ATOMIC); | |
125 | ||
126 | if (ntbl && leaf) { | |
127 | for (i = 0; i < PAGE_SIZE / sizeof(ntbl[0]); i++) | |
128 | INIT_RHT_NULLS_HEAD(ntbl[i].bucket); | |
129 | } | |
130 | ||
131 | if (cmpxchg((union nested_table **)prev, NULL, ntbl) == NULL) | |
132 | return ntbl; | |
133 | /* Raced with another thread. */ | |
134 | kfree(ntbl); | |
135 | return rcu_dereference(*prev); | |
136 | } | |
137 | ||
138 | static struct bucket_table *nested_bucket_table_alloc(struct rhashtable *ht, | |
139 | size_t nbuckets, | |
140 | gfp_t gfp) | |
141 | { | |
142 | const unsigned int shift = PAGE_SHIFT - ilog2(sizeof(void *)); | |
143 | struct bucket_table *tbl; | |
144 | size_t size; | |
145 | ||
146 | if (nbuckets < (1 << (shift + 1))) | |
147 | return NULL; | |
148 | ||
149 | size = sizeof(*tbl) + sizeof(tbl->buckets[0]); | |
150 | ||
151 | tbl = kzalloc(size, gfp); | |
152 | if (!tbl) | |
153 | return NULL; | |
154 | ||
155 | if (!nested_table_alloc(ht, (union nested_table __rcu **)tbl->buckets, | |
156 | false)) { | |
157 | kfree(tbl); | |
158 | return NULL; | |
159 | } | |
160 | ||
161 | tbl->nest = (ilog2(nbuckets) - 1) % shift + 1; | |
162 | ||
163 | return tbl; | |
164 | } | |
165 | ||
166 | static struct bucket_table *bucket_table_alloc(struct rhashtable *ht, | |
167 | size_t nbuckets, | |
168 | gfp_t gfp) | |
169 | { | |
170 | struct bucket_table *tbl = NULL; | |
171 | size_t size; | |
172 | int i; | |
173 | static struct lock_class_key __key; | |
174 | ||
175 | tbl = kvzalloc(struct_size(tbl, buckets, nbuckets), gfp); | |
176 | ||
177 | size = nbuckets; | |
178 | ||
179 | if (tbl == NULL && (gfp & ~__GFP_NOFAIL) != GFP_KERNEL) { | |
180 | tbl = nested_bucket_table_alloc(ht, nbuckets, gfp); | |
181 | nbuckets = 0; | |
182 | } | |
183 | ||
184 | if (tbl == NULL) | |
185 | return NULL; | |
186 | ||
187 | lockdep_init_map(&tbl->dep_map, "rhashtable_bucket", &__key, 0); | |
188 | ||
189 | tbl->size = size; | |
190 | ||
191 | rcu_head_init(&tbl->rcu); | |
192 | INIT_LIST_HEAD(&tbl->walkers); | |
193 | ||
194 | tbl->hash_rnd = get_random_u32(); | |
195 | ||
196 | for (i = 0; i < nbuckets; i++) | |
197 | INIT_RHT_NULLS_HEAD(tbl->buckets[i]); | |
198 | ||
199 | return tbl; | |
200 | } | |
201 | ||
202 | static struct bucket_table *rhashtable_last_table(struct rhashtable *ht, | |
203 | struct bucket_table *tbl) | |
204 | { | |
205 | struct bucket_table *new_tbl; | |
206 | ||
207 | do { | |
208 | new_tbl = tbl; | |
209 | tbl = rht_dereference_rcu(tbl->future_tbl, ht); | |
210 | } while (tbl); | |
211 | ||
212 | return new_tbl; | |
213 | } | |
214 | ||
215 | static int rhashtable_rehash_one(struct rhashtable *ht, | |
216 | struct rhash_lock_head **bkt, | |
217 | unsigned int old_hash) | |
218 | { | |
219 | struct bucket_table *old_tbl = rht_dereference(ht->tbl, ht); | |
220 | struct bucket_table *new_tbl = rhashtable_last_table(ht, old_tbl); | |
221 | int err = -EAGAIN; | |
222 | struct rhash_head *head, *next, *entry; | |
223 | struct rhash_head __rcu **pprev = NULL; | |
224 | unsigned int new_hash; | |
225 | ||
226 | if (new_tbl->nest) | |
227 | goto out; | |
228 | ||
229 | err = -ENOENT; | |
230 | ||
231 | rht_for_each_from(entry, rht_ptr(bkt, old_tbl, old_hash), | |
232 | old_tbl, old_hash) { | |
233 | err = 0; | |
234 | next = rht_dereference_bucket(entry->next, old_tbl, old_hash); | |
235 | ||
236 | if (rht_is_a_nulls(next)) | |
237 | break; | |
238 | ||
239 | pprev = &entry->next; | |
240 | } | |
241 | ||
242 | if (err) | |
243 | goto out; | |
244 | ||
245 | new_hash = head_hashfn(ht, new_tbl, entry); | |
246 | ||
247 | rht_lock_nested(new_tbl, &new_tbl->buckets[new_hash], SINGLE_DEPTH_NESTING); | |
248 | ||
249 | head = rht_ptr(new_tbl->buckets + new_hash, new_tbl, new_hash); | |
250 | ||
251 | RCU_INIT_POINTER(entry->next, head); | |
252 | ||
253 | rht_assign_unlock(new_tbl, &new_tbl->buckets[new_hash], entry); | |
254 | ||
255 | if (pprev) | |
256 | rcu_assign_pointer(*pprev, next); | |
257 | else | |
258 | /* Need to preserved the bit lock. */ | |
259 | rht_assign_locked(bkt, next); | |
260 | ||
261 | out: | |
262 | return err; | |
263 | } | |
264 | ||
265 | static int rhashtable_rehash_chain(struct rhashtable *ht, | |
266 | unsigned int old_hash) | |
267 | { | |
268 | struct bucket_table *old_tbl = rht_dereference(ht->tbl, ht); | |
269 | struct rhash_lock_head **bkt = rht_bucket_var(old_tbl, old_hash); | |
270 | int err; | |
271 | ||
272 | if (!bkt) | |
273 | return 0; | |
274 | rht_lock(old_tbl, bkt); | |
275 | ||
276 | while (!(err = rhashtable_rehash_one(ht, bkt, old_hash))) | |
277 | ; | |
278 | ||
279 | if (err == -ENOENT) | |
280 | err = 0; | |
281 | rht_unlock(old_tbl, bkt); | |
282 | ||
283 | return err; | |
284 | } | |
285 | ||
286 | static int rhashtable_rehash_attach(struct rhashtable *ht, | |
287 | struct bucket_table *old_tbl, | |
288 | struct bucket_table *new_tbl) | |
289 | { | |
290 | /* Make insertions go into the new, empty table right away. Deletions | |
291 | * and lookups will be attempted in both tables until we synchronize. | |
292 | * As cmpxchg() provides strong barriers, we do not need | |
293 | * rcu_assign_pointer(). | |
294 | */ | |
295 | ||
296 | if (cmpxchg((struct bucket_table **)&old_tbl->future_tbl, NULL, | |
297 | new_tbl) != NULL) | |
298 | return -EEXIST; | |
299 | ||
300 | return 0; | |
301 | } | |
302 | ||
303 | static int rhashtable_rehash_table(struct rhashtable *ht) | |
304 | { | |
305 | struct bucket_table *old_tbl = rht_dereference(ht->tbl, ht); | |
306 | struct bucket_table *new_tbl; | |
307 | struct rhashtable_walker *walker; | |
308 | unsigned int old_hash; | |
309 | int err; | |
310 | ||
311 | new_tbl = rht_dereference(old_tbl->future_tbl, ht); | |
312 | if (!new_tbl) | |
313 | return 0; | |
314 | ||
315 | for (old_hash = 0; old_hash < old_tbl->size; old_hash++) { | |
316 | err = rhashtable_rehash_chain(ht, old_hash); | |
317 | if (err) | |
318 | return err; | |
319 | cond_resched(); | |
320 | } | |
321 | ||
322 | /* Publish the new table pointer. */ | |
323 | rcu_assign_pointer(ht->tbl, new_tbl); | |
324 | ||
325 | spin_lock(&ht->lock); | |
326 | list_for_each_entry(walker, &old_tbl->walkers, list) | |
327 | walker->tbl = NULL; | |
328 | ||
329 | /* Wait for readers. All new readers will see the new | |
330 | * table, and thus no references to the old table will | |
331 | * remain. | |
332 | * We do this inside the locked region so that | |
333 | * rhashtable_walk_stop() can use rcu_head_after_call_rcu() | |
334 | * to check if it should not re-link the table. | |
335 | */ | |
336 | call_rcu(&old_tbl->rcu, bucket_table_free_rcu); | |
337 | spin_unlock(&ht->lock); | |
338 | ||
339 | return rht_dereference(new_tbl->future_tbl, ht) ? -EAGAIN : 0; | |
340 | } | |
341 | ||
342 | static int rhashtable_rehash_alloc(struct rhashtable *ht, | |
343 | struct bucket_table *old_tbl, | |
344 | unsigned int size) | |
345 | { | |
346 | struct bucket_table *new_tbl; | |
347 | int err; | |
348 | ||
349 | ASSERT_RHT_MUTEX(ht); | |
350 | ||
351 | new_tbl = bucket_table_alloc(ht, size, GFP_KERNEL); | |
352 | if (new_tbl == NULL) | |
353 | return -ENOMEM; | |
354 | ||
355 | err = rhashtable_rehash_attach(ht, old_tbl, new_tbl); | |
356 | if (err) | |
357 | bucket_table_free(new_tbl); | |
358 | ||
359 | return err; | |
360 | } | |
361 | ||
362 | /** | |
363 | * rhashtable_shrink - Shrink hash table while allowing concurrent lookups | |
364 | * @ht: the hash table to shrink | |
365 | * | |
366 | * This function shrinks the hash table to fit, i.e., the smallest | |
367 | * size would not cause it to expand right away automatically. | |
368 | * | |
369 | * The caller must ensure that no concurrent resizing occurs by holding | |
370 | * ht->mutex. | |
371 | * | |
372 | * The caller must ensure that no concurrent table mutations take place. | |
373 | * It is however valid to have concurrent lookups if they are RCU protected. | |
374 | * | |
375 | * It is valid to have concurrent insertions and deletions protected by per | |
376 | * bucket locks or concurrent RCU protected lookups and traversals. | |
377 | */ | |
378 | static int rhashtable_shrink(struct rhashtable *ht) | |
379 | { | |
380 | struct bucket_table *old_tbl = rht_dereference(ht->tbl, ht); | |
381 | unsigned int nelems = atomic_read(&ht->nelems); | |
382 | unsigned int size = 0; | |
383 | ||
384 | if (nelems) | |
385 | size = roundup_pow_of_two(nelems * 3 / 2); | |
386 | if (size < ht->p.min_size) | |
387 | size = ht->p.min_size; | |
388 | ||
389 | if (old_tbl->size <= size) | |
390 | return 0; | |
391 | ||
392 | if (rht_dereference(old_tbl->future_tbl, ht)) | |
393 | return -EEXIST; | |
394 | ||
395 | return rhashtable_rehash_alloc(ht, old_tbl, size); | |
396 | } | |
397 | ||
398 | static void rht_deferred_worker(struct work_struct *work) | |
399 | { | |
400 | struct rhashtable *ht; | |
401 | struct bucket_table *tbl; | |
402 | int err = 0; | |
403 | ||
404 | ht = container_of(work, struct rhashtable, run_work); | |
405 | mutex_lock(&ht->mutex); | |
406 | ||
407 | tbl = rht_dereference(ht->tbl, ht); | |
408 | tbl = rhashtable_last_table(ht, tbl); | |
409 | ||
410 | if (rht_grow_above_75(ht, tbl)) | |
411 | err = rhashtable_rehash_alloc(ht, tbl, tbl->size * 2); | |
412 | else if (ht->p.automatic_shrinking && rht_shrink_below_30(ht, tbl)) | |
413 | err = rhashtable_shrink(ht); | |
414 | else if (tbl->nest) | |
415 | err = rhashtable_rehash_alloc(ht, tbl, tbl->size); | |
416 | ||
417 | if (!err || err == -EEXIST) { | |
418 | int nerr; | |
419 | ||
420 | nerr = rhashtable_rehash_table(ht); | |
421 | err = err ?: nerr; | |
422 | } | |
423 | ||
424 | mutex_unlock(&ht->mutex); | |
425 | ||
426 | if (err) | |
427 | schedule_work(&ht->run_work); | |
428 | } | |
429 | ||
430 | static int rhashtable_insert_rehash(struct rhashtable *ht, | |
431 | struct bucket_table *tbl) | |
432 | { | |
433 | struct bucket_table *old_tbl; | |
434 | struct bucket_table *new_tbl; | |
435 | unsigned int size; | |
436 | int err; | |
437 | ||
438 | old_tbl = rht_dereference_rcu(ht->tbl, ht); | |
439 | ||
440 | size = tbl->size; | |
441 | ||
442 | err = -EBUSY; | |
443 | ||
444 | if (rht_grow_above_75(ht, tbl)) | |
445 | size *= 2; | |
446 | /* Do not schedule more than one rehash */ | |
447 | else if (old_tbl != tbl) | |
448 | goto fail; | |
449 | ||
450 | err = -ENOMEM; | |
451 | ||
452 | new_tbl = bucket_table_alloc(ht, size, GFP_ATOMIC | __GFP_NOWARN); | |
453 | if (new_tbl == NULL) | |
454 | goto fail; | |
455 | ||
456 | err = rhashtable_rehash_attach(ht, tbl, new_tbl); | |
457 | if (err) { | |
458 | bucket_table_free(new_tbl); | |
459 | if (err == -EEXIST) | |
460 | err = 0; | |
461 | } else | |
462 | schedule_work(&ht->run_work); | |
463 | ||
464 | return err; | |
465 | ||
466 | fail: | |
467 | /* Do not fail the insert if someone else did a rehash. */ | |
468 | if (likely(rcu_access_pointer(tbl->future_tbl))) | |
469 | return 0; | |
470 | ||
471 | /* Schedule async rehash to retry allocation in process context. */ | |
472 | if (err == -ENOMEM) | |
473 | schedule_work(&ht->run_work); | |
474 | ||
475 | return err; | |
476 | } | |
477 | ||
478 | static void *rhashtable_lookup_one(struct rhashtable *ht, | |
479 | struct rhash_lock_head **bkt, | |
480 | struct bucket_table *tbl, unsigned int hash, | |
481 | const void *key, struct rhash_head *obj) | |
482 | { | |
483 | struct rhashtable_compare_arg arg = { | |
484 | .ht = ht, | |
485 | .key = key, | |
486 | }; | |
487 | struct rhash_head __rcu **pprev = NULL; | |
488 | struct rhash_head *head; | |
489 | int elasticity; | |
490 | ||
491 | elasticity = RHT_ELASTICITY; | |
492 | rht_for_each_from(head, rht_ptr(bkt, tbl, hash), tbl, hash) { | |
493 | struct rhlist_head *list; | |
494 | struct rhlist_head *plist; | |
495 | ||
496 | elasticity--; | |
497 | if (!key || | |
498 | (ht->p.obj_cmpfn ? | |
499 | ht->p.obj_cmpfn(&arg, rht_obj(ht, head)) : | |
500 | rhashtable_compare(&arg, rht_obj(ht, head)))) { | |
501 | pprev = &head->next; | |
502 | continue; | |
503 | } | |
504 | ||
505 | if (!ht->rhlist) | |
506 | return rht_obj(ht, head); | |
507 | ||
508 | list = container_of(obj, struct rhlist_head, rhead); | |
509 | plist = container_of(head, struct rhlist_head, rhead); | |
510 | ||
511 | RCU_INIT_POINTER(list->next, plist); | |
512 | head = rht_dereference_bucket(head->next, tbl, hash); | |
513 | RCU_INIT_POINTER(list->rhead.next, head); | |
514 | if (pprev) | |
515 | rcu_assign_pointer(*pprev, obj); | |
516 | else | |
517 | /* Need to preserve the bit lock */ | |
518 | rht_assign_locked(bkt, obj); | |
519 | ||
520 | return NULL; | |
521 | } | |
522 | ||
523 | if (elasticity <= 0) | |
524 | return ERR_PTR(-EAGAIN); | |
525 | ||
526 | return ERR_PTR(-ENOENT); | |
527 | } | |
528 | ||
529 | static struct bucket_table *rhashtable_insert_one(struct rhashtable *ht, | |
530 | struct rhash_lock_head **bkt, | |
531 | struct bucket_table *tbl, | |
532 | unsigned int hash, | |
533 | struct rhash_head *obj, | |
534 | void *data) | |
535 | { | |
536 | struct bucket_table *new_tbl; | |
537 | struct rhash_head *head; | |
538 | ||
539 | if (!IS_ERR_OR_NULL(data)) | |
540 | return ERR_PTR(-EEXIST); | |
541 | ||
542 | if (PTR_ERR(data) != -EAGAIN && PTR_ERR(data) != -ENOENT) | |
543 | return ERR_CAST(data); | |
544 | ||
545 | new_tbl = rht_dereference_rcu(tbl->future_tbl, ht); | |
546 | if (new_tbl) | |
547 | return new_tbl; | |
548 | ||
549 | if (PTR_ERR(data) != -ENOENT) | |
550 | return ERR_CAST(data); | |
551 | ||
552 | if (unlikely(rht_grow_above_max(ht, tbl))) | |
553 | return ERR_PTR(-E2BIG); | |
554 | ||
555 | if (unlikely(rht_grow_above_100(ht, tbl))) | |
556 | return ERR_PTR(-EAGAIN); | |
557 | ||
558 | head = rht_ptr(bkt, tbl, hash); | |
559 | ||
560 | RCU_INIT_POINTER(obj->next, head); | |
561 | if (ht->rhlist) { | |
562 | struct rhlist_head *list; | |
563 | ||
564 | list = container_of(obj, struct rhlist_head, rhead); | |
565 | RCU_INIT_POINTER(list->next, NULL); | |
566 | } | |
567 | ||
568 | /* bkt is always the head of the list, so it holds | |
569 | * the lock, which we need to preserve | |
570 | */ | |
571 | rht_assign_locked(bkt, obj); | |
572 | ||
573 | atomic_inc(&ht->nelems); | |
574 | if (rht_grow_above_75(ht, tbl)) | |
575 | schedule_work(&ht->run_work); | |
576 | ||
577 | return NULL; | |
578 | } | |
579 | ||
580 | static void *rhashtable_try_insert(struct rhashtable *ht, const void *key, | |
581 | struct rhash_head *obj) | |
582 | { | |
583 | struct bucket_table *new_tbl; | |
584 | struct bucket_table *tbl; | |
585 | struct rhash_lock_head **bkt; | |
586 | unsigned int hash; | |
587 | void *data; | |
588 | ||
589 | new_tbl = rcu_dereference(ht->tbl); | |
590 | ||
591 | do { | |
592 | tbl = new_tbl; | |
593 | hash = rht_head_hashfn(ht, tbl, obj, ht->p); | |
594 | if (rcu_access_pointer(tbl->future_tbl)) | |
595 | /* Failure is OK */ | |
596 | bkt = rht_bucket_var(tbl, hash); | |
597 | else | |
598 | bkt = rht_bucket_insert(ht, tbl, hash); | |
599 | if (bkt == NULL) { | |
600 | new_tbl = rht_dereference_rcu(tbl->future_tbl, ht); | |
601 | data = ERR_PTR(-EAGAIN); | |
602 | } else { | |
603 | rht_lock(tbl, bkt); | |
604 | data = rhashtable_lookup_one(ht, bkt, tbl, | |
605 | hash, key, obj); | |
606 | new_tbl = rhashtable_insert_one(ht, bkt, tbl, | |
607 | hash, obj, data); | |
608 | if (PTR_ERR(new_tbl) != -EEXIST) | |
609 | data = ERR_CAST(new_tbl); | |
610 | ||
611 | rht_unlock(tbl, bkt); | |
612 | } | |
613 | } while (!IS_ERR_OR_NULL(new_tbl)); | |
614 | ||
615 | if (PTR_ERR(data) == -EAGAIN) | |
616 | data = ERR_PTR(rhashtable_insert_rehash(ht, tbl) ?: | |
617 | -EAGAIN); | |
618 | ||
619 | return data; | |
620 | } | |
621 | ||
622 | void *rhashtable_insert_slow(struct rhashtable *ht, const void *key, | |
623 | struct rhash_head *obj) | |
624 | { | |
625 | void *data; | |
626 | ||
627 | do { | |
628 | rcu_read_lock(); | |
629 | data = rhashtable_try_insert(ht, key, obj); | |
630 | rcu_read_unlock(); | |
631 | } while (PTR_ERR(data) == -EAGAIN); | |
632 | ||
633 | return data; | |
634 | } | |
635 | EXPORT_SYMBOL_GPL(rhashtable_insert_slow); | |
636 | ||
637 | /** | |
638 | * rhashtable_walk_enter - Initialise an iterator | |
639 | * @ht: Table to walk over | |
640 | * @iter: Hash table Iterator | |
641 | * | |
642 | * This function prepares a hash table walk. | |
643 | * | |
644 | * Note that if you restart a walk after rhashtable_walk_stop you | |
645 | * may see the same object twice. Also, you may miss objects if | |
646 | * there are removals in between rhashtable_walk_stop and the next | |
647 | * call to rhashtable_walk_start. | |
648 | * | |
649 | * For a completely stable walk you should construct your own data | |
650 | * structure outside the hash table. | |
651 | * | |
652 | * This function may be called from any process context, including | |
653 | * non-preemptable context, but cannot be called from softirq or | |
654 | * hardirq context. | |
655 | * | |
656 | * You must call rhashtable_walk_exit after this function returns. | |
657 | */ | |
658 | void rhashtable_walk_enter(struct rhashtable *ht, struct rhashtable_iter *iter) | |
659 | { | |
660 | iter->ht = ht; | |
661 | iter->p = NULL; | |
662 | iter->slot = 0; | |
663 | iter->skip = 0; | |
664 | iter->end_of_table = 0; | |
665 | ||
666 | spin_lock(&ht->lock); | |
667 | iter->walker.tbl = | |
668 | rcu_dereference_protected(ht->tbl, lockdep_is_held(&ht->lock)); | |
669 | list_add(&iter->walker.list, &iter->walker.tbl->walkers); | |
670 | spin_unlock(&ht->lock); | |
671 | } | |
672 | EXPORT_SYMBOL_GPL(rhashtable_walk_enter); | |
673 | ||
674 | /** | |
675 | * rhashtable_walk_exit - Free an iterator | |
676 | * @iter: Hash table Iterator | |
677 | * | |
678 | * This function frees resources allocated by rhashtable_walk_enter. | |
679 | */ | |
680 | void rhashtable_walk_exit(struct rhashtable_iter *iter) | |
681 | { | |
682 | spin_lock(&iter->ht->lock); | |
683 | if (iter->walker.tbl) | |
684 | list_del(&iter->walker.list); | |
685 | spin_unlock(&iter->ht->lock); | |
686 | } | |
687 | EXPORT_SYMBOL_GPL(rhashtable_walk_exit); | |
688 | ||
689 | /** | |
690 | * rhashtable_walk_start_check - Start a hash table walk | |
691 | * @iter: Hash table iterator | |
692 | * | |
693 | * Start a hash table walk at the current iterator position. Note that we take | |
694 | * the RCU lock in all cases including when we return an error. So you must | |
695 | * always call rhashtable_walk_stop to clean up. | |
696 | * | |
697 | * Returns zero if successful. | |
698 | * | |
699 | * Returns -EAGAIN if resize event occured. Note that the iterator | |
700 | * will rewind back to the beginning and you may use it immediately | |
701 | * by calling rhashtable_walk_next. | |
702 | * | |
703 | * rhashtable_walk_start is defined as an inline variant that returns | |
704 | * void. This is preferred in cases where the caller would ignore | |
705 | * resize events and always continue. | |
706 | */ | |
707 | int rhashtable_walk_start_check(struct rhashtable_iter *iter) | |
708 | __acquires(RCU) | |
709 | { | |
710 | struct rhashtable *ht = iter->ht; | |
711 | bool rhlist = ht->rhlist; | |
712 | ||
713 | rcu_read_lock(); | |
714 | ||
715 | spin_lock(&ht->lock); | |
716 | if (iter->walker.tbl) | |
717 | list_del(&iter->walker.list); | |
718 | spin_unlock(&ht->lock); | |
719 | ||
720 | if (iter->end_of_table) | |
721 | return 0; | |
722 | if (!iter->walker.tbl) { | |
723 | iter->walker.tbl = rht_dereference_rcu(ht->tbl, ht); | |
724 | iter->slot = 0; | |
725 | iter->skip = 0; | |
726 | return -EAGAIN; | |
727 | } | |
728 | ||
729 | if (iter->p && !rhlist) { | |
730 | /* | |
731 | * We need to validate that 'p' is still in the table, and | |
732 | * if so, update 'skip' | |
733 | */ | |
734 | struct rhash_head *p; | |
735 | int skip = 0; | |
736 | rht_for_each_rcu(p, iter->walker.tbl, iter->slot) { | |
737 | skip++; | |
738 | if (p == iter->p) { | |
739 | iter->skip = skip; | |
740 | goto found; | |
741 | } | |
742 | } | |
743 | iter->p = NULL; | |
744 | } else if (iter->p && rhlist) { | |
745 | /* Need to validate that 'list' is still in the table, and | |
746 | * if so, update 'skip' and 'p'. | |
747 | */ | |
748 | struct rhash_head *p; | |
749 | struct rhlist_head *list; | |
750 | int skip = 0; | |
751 | rht_for_each_rcu(p, iter->walker.tbl, iter->slot) { | |
752 | for (list = container_of(p, struct rhlist_head, rhead); | |
753 | list; | |
754 | list = rcu_dereference(list->next)) { | |
755 | skip++; | |
756 | if (list == iter->list) { | |
757 | iter->p = p; | |
758 | iter->skip = skip; | |
759 | goto found; | |
760 | } | |
761 | } | |
762 | } | |
763 | iter->p = NULL; | |
764 | } | |
765 | found: | |
766 | return 0; | |
767 | } | |
768 | EXPORT_SYMBOL_GPL(rhashtable_walk_start_check); | |
769 | ||
770 | /** | |
771 | * __rhashtable_walk_find_next - Find the next element in a table (or the first | |
772 | * one in case of a new walk). | |
773 | * | |
774 | * @iter: Hash table iterator | |
775 | * | |
776 | * Returns the found object or NULL when the end of the table is reached. | |
777 | * | |
778 | * Returns -EAGAIN if resize event occurred. | |
779 | */ | |
780 | static void *__rhashtable_walk_find_next(struct rhashtable_iter *iter) | |
781 | { | |
782 | struct bucket_table *tbl = iter->walker.tbl; | |
783 | struct rhlist_head *list = iter->list; | |
784 | struct rhashtable *ht = iter->ht; | |
785 | struct rhash_head *p = iter->p; | |
786 | bool rhlist = ht->rhlist; | |
787 | ||
788 | if (!tbl) | |
789 | return NULL; | |
790 | ||
791 | for (; iter->slot < tbl->size; iter->slot++) { | |
792 | int skip = iter->skip; | |
793 | ||
794 | rht_for_each_rcu(p, tbl, iter->slot) { | |
795 | if (rhlist) { | |
796 | list = container_of(p, struct rhlist_head, | |
797 | rhead); | |
798 | do { | |
799 | if (!skip) | |
800 | goto next; | |
801 | skip--; | |
802 | list = rcu_dereference(list->next); | |
803 | } while (list); | |
804 | ||
805 | continue; | |
806 | } | |
807 | if (!skip) | |
808 | break; | |
809 | skip--; | |
810 | } | |
811 | ||
812 | next: | |
813 | if (!rht_is_a_nulls(p)) { | |
814 | iter->skip++; | |
815 | iter->p = p; | |
816 | iter->list = list; | |
817 | return rht_obj(ht, rhlist ? &list->rhead : p); | |
818 | } | |
819 | ||
820 | iter->skip = 0; | |
821 | } | |
822 | ||
823 | iter->p = NULL; | |
824 | ||
825 | /* Ensure we see any new tables. */ | |
826 | smp_rmb(); | |
827 | ||
828 | iter->walker.tbl = rht_dereference_rcu(tbl->future_tbl, ht); | |
829 | if (iter->walker.tbl) { | |
830 | iter->slot = 0; | |
831 | iter->skip = 0; | |
832 | return ERR_PTR(-EAGAIN); | |
833 | } else { | |
834 | iter->end_of_table = true; | |
835 | } | |
836 | ||
837 | return NULL; | |
838 | } | |
839 | ||
840 | /** | |
841 | * rhashtable_walk_next - Return the next object and advance the iterator | |
842 | * @iter: Hash table iterator | |
843 | * | |
844 | * Note that you must call rhashtable_walk_stop when you are finished | |
845 | * with the walk. | |
846 | * | |
847 | * Returns the next object or NULL when the end of the table is reached. | |
848 | * | |
849 | * Returns -EAGAIN if resize event occurred. Note that the iterator | |
850 | * will rewind back to the beginning and you may continue to use it. | |
851 | */ | |
852 | void *rhashtable_walk_next(struct rhashtable_iter *iter) | |
853 | { | |
854 | struct rhlist_head *list = iter->list; | |
855 | struct rhashtable *ht = iter->ht; | |
856 | struct rhash_head *p = iter->p; | |
857 | bool rhlist = ht->rhlist; | |
858 | ||
859 | if (p) { | |
860 | if (!rhlist || !(list = rcu_dereference(list->next))) { | |
861 | p = rcu_dereference(p->next); | |
862 | list = container_of(p, struct rhlist_head, rhead); | |
863 | } | |
864 | if (!rht_is_a_nulls(p)) { | |
865 | iter->skip++; | |
866 | iter->p = p; | |
867 | iter->list = list; | |
868 | return rht_obj(ht, rhlist ? &list->rhead : p); | |
869 | } | |
870 | ||
871 | /* At the end of this slot, switch to next one and then find | |
872 | * next entry from that point. | |
873 | */ | |
874 | iter->skip = 0; | |
875 | iter->slot++; | |
876 | } | |
877 | ||
878 | return __rhashtable_walk_find_next(iter); | |
879 | } | |
880 | EXPORT_SYMBOL_GPL(rhashtable_walk_next); | |
881 | ||
882 | /** | |
883 | * rhashtable_walk_peek - Return the next object but don't advance the iterator | |
884 | * @iter: Hash table iterator | |
885 | * | |
886 | * Returns the next object or NULL when the end of the table is reached. | |
887 | * | |
888 | * Returns -EAGAIN if resize event occurred. Note that the iterator | |
889 | * will rewind back to the beginning and you may continue to use it. | |
890 | */ | |
891 | void *rhashtable_walk_peek(struct rhashtable_iter *iter) | |
892 | { | |
893 | struct rhlist_head *list = iter->list; | |
894 | struct rhashtable *ht = iter->ht; | |
895 | struct rhash_head *p = iter->p; | |
896 | ||
897 | if (p) | |
898 | return rht_obj(ht, ht->rhlist ? &list->rhead : p); | |
899 | ||
900 | /* No object found in current iter, find next one in the table. */ | |
901 | ||
902 | if (iter->skip) { | |
903 | /* A nonzero skip value points to the next entry in the table | |
904 | * beyond that last one that was found. Decrement skip so | |
905 | * we find the current value. __rhashtable_walk_find_next | |
906 | * will restore the original value of skip assuming that | |
907 | * the table hasn't changed. | |
908 | */ | |
909 | iter->skip--; | |
910 | } | |
911 | ||
912 | return __rhashtable_walk_find_next(iter); | |
913 | } | |
914 | EXPORT_SYMBOL_GPL(rhashtable_walk_peek); | |
915 | ||
916 | /** | |
917 | * rhashtable_walk_stop - Finish a hash table walk | |
918 | * @iter: Hash table iterator | |
919 | * | |
920 | * Finish a hash table walk. Does not reset the iterator to the start of the | |
921 | * hash table. | |
922 | */ | |
923 | void rhashtable_walk_stop(struct rhashtable_iter *iter) | |
924 | __releases(RCU) | |
925 | { | |
926 | struct rhashtable *ht; | |
927 | struct bucket_table *tbl = iter->walker.tbl; | |
928 | ||
929 | if (!tbl) | |
930 | goto out; | |
931 | ||
932 | ht = iter->ht; | |
933 | ||
934 | spin_lock(&ht->lock); | |
935 | if (rcu_head_after_call_rcu(&tbl->rcu, bucket_table_free_rcu)) | |
936 | /* This bucket table is being freed, don't re-link it. */ | |
937 | iter->walker.tbl = NULL; | |
938 | else | |
939 | list_add(&iter->walker.list, &tbl->walkers); | |
940 | spin_unlock(&ht->lock); | |
941 | ||
942 | out: | |
943 | rcu_read_unlock(); | |
944 | } | |
945 | EXPORT_SYMBOL_GPL(rhashtable_walk_stop); | |
946 | ||
947 | static size_t rounded_hashtable_size(const struct rhashtable_params *params) | |
948 | { | |
949 | size_t retsize; | |
950 | ||
951 | if (params->nelem_hint) | |
952 | retsize = max(roundup_pow_of_two(params->nelem_hint * 4 / 3), | |
953 | (unsigned long)params->min_size); | |
954 | else | |
955 | retsize = max(HASH_DEFAULT_SIZE, | |
956 | (unsigned long)params->min_size); | |
957 | ||
958 | return retsize; | |
959 | } | |
960 | ||
961 | static u32 rhashtable_jhash2(const void *key, u32 length, u32 seed) | |
962 | { | |
963 | return jhash2(key, length, seed); | |
964 | } | |
965 | ||
966 | /** | |
967 | * rhashtable_init - initialize a new hash table | |
968 | * @ht: hash table to be initialized | |
969 | * @params: configuration parameters | |
970 | * | |
971 | * Initializes a new hash table based on the provided configuration | |
972 | * parameters. A table can be configured either with a variable or | |
973 | * fixed length key: | |
974 | * | |
975 | * Configuration Example 1: Fixed length keys | |
976 | * struct test_obj { | |
977 | * int key; | |
978 | * void * my_member; | |
979 | * struct rhash_head node; | |
980 | * }; | |
981 | * | |
982 | * struct rhashtable_params params = { | |
983 | * .head_offset = offsetof(struct test_obj, node), | |
984 | * .key_offset = offsetof(struct test_obj, key), | |
985 | * .key_len = sizeof(int), | |
986 | * .hashfn = jhash, | |
987 | * }; | |
988 | * | |
989 | * Configuration Example 2: Variable length keys | |
990 | * struct test_obj { | |
991 | * [...] | |
992 | * struct rhash_head node; | |
993 | * }; | |
994 | * | |
995 | * u32 my_hash_fn(const void *data, u32 len, u32 seed) | |
996 | * { | |
997 | * struct test_obj *obj = data; | |
998 | * | |
999 | * return [... hash ...]; | |
1000 | * } | |
1001 | * | |
1002 | * struct rhashtable_params params = { | |
1003 | * .head_offset = offsetof(struct test_obj, node), | |
1004 | * .hashfn = jhash, | |
1005 | * .obj_hashfn = my_hash_fn, | |
1006 | * }; | |
1007 | */ | |
1008 | int rhashtable_init(struct rhashtable *ht, | |
1009 | const struct rhashtable_params *params) | |
1010 | { | |
1011 | struct bucket_table *tbl; | |
1012 | size_t size; | |
1013 | ||
1014 | if ((!params->key_len && !params->obj_hashfn) || | |
1015 | (params->obj_hashfn && !params->obj_cmpfn)) | |
1016 | return -EINVAL; | |
1017 | ||
1018 | memset(ht, 0, sizeof(*ht)); | |
1019 | mutex_init(&ht->mutex); | |
1020 | spin_lock_init(&ht->lock); | |
1021 | memcpy(&ht->p, params, sizeof(*params)); | |
1022 | ||
1023 | if (params->min_size) | |
1024 | ht->p.min_size = roundup_pow_of_two(params->min_size); | |
1025 | ||
1026 | /* Cap total entries at 2^31 to avoid nelems overflow. */ | |
1027 | ht->max_elems = 1u << 31; | |
1028 | ||
1029 | if (params->max_size) { | |
1030 | ht->p.max_size = rounddown_pow_of_two(params->max_size); | |
1031 | if (ht->p.max_size < ht->max_elems / 2) | |
1032 | ht->max_elems = ht->p.max_size * 2; | |
1033 | } | |
1034 | ||
1035 | ht->p.min_size = max_t(u16, ht->p.min_size, HASH_MIN_SIZE); | |
1036 | ||
1037 | size = rounded_hashtable_size(&ht->p); | |
1038 | ||
1039 | ht->key_len = ht->p.key_len; | |
1040 | if (!params->hashfn) { | |
1041 | ht->p.hashfn = jhash; | |
1042 | ||
1043 | if (!(ht->key_len & (sizeof(u32) - 1))) { | |
1044 | ht->key_len /= sizeof(u32); | |
1045 | ht->p.hashfn = rhashtable_jhash2; | |
1046 | } | |
1047 | } | |
1048 | ||
1049 | /* | |
1050 | * This is api initialization and thus we need to guarantee the | |
1051 | * initial rhashtable allocation. Upon failure, retry with the | |
1052 | * smallest possible size with __GFP_NOFAIL semantics. | |
1053 | */ | |
1054 | tbl = bucket_table_alloc(ht, size, GFP_KERNEL); | |
1055 | if (unlikely(tbl == NULL)) { | |
1056 | size = max_t(u16, ht->p.min_size, HASH_MIN_SIZE); | |
1057 | tbl = bucket_table_alloc(ht, size, GFP_KERNEL | __GFP_NOFAIL); | |
1058 | } | |
1059 | ||
1060 | atomic_set(&ht->nelems, 0); | |
1061 | ||
1062 | RCU_INIT_POINTER(ht->tbl, tbl); | |
1063 | ||
1064 | INIT_WORK(&ht->run_work, rht_deferred_worker); | |
1065 | ||
1066 | return 0; | |
1067 | } | |
1068 | EXPORT_SYMBOL_GPL(rhashtable_init); | |
1069 | ||
1070 | /** | |
1071 | * rhltable_init - initialize a new hash list table | |
1072 | * @hlt: hash list table to be initialized | |
1073 | * @params: configuration parameters | |
1074 | * | |
1075 | * Initializes a new hash list table. | |
1076 | * | |
1077 | * See documentation for rhashtable_init. | |
1078 | */ | |
1079 | int rhltable_init(struct rhltable *hlt, const struct rhashtable_params *params) | |
1080 | { | |
1081 | int err; | |
1082 | ||
1083 | err = rhashtable_init(&hlt->ht, params); | |
1084 | hlt->ht.rhlist = true; | |
1085 | return err; | |
1086 | } | |
1087 | EXPORT_SYMBOL_GPL(rhltable_init); | |
1088 | ||
1089 | static void rhashtable_free_one(struct rhashtable *ht, struct rhash_head *obj, | |
1090 | void (*free_fn)(void *ptr, void *arg), | |
1091 | void *arg) | |
1092 | { | |
1093 | struct rhlist_head *list; | |
1094 | ||
1095 | if (!ht->rhlist) { | |
1096 | free_fn(rht_obj(ht, obj), arg); | |
1097 | return; | |
1098 | } | |
1099 | ||
1100 | list = container_of(obj, struct rhlist_head, rhead); | |
1101 | do { | |
1102 | obj = &list->rhead; | |
1103 | list = rht_dereference(list->next, ht); | |
1104 | free_fn(rht_obj(ht, obj), arg); | |
1105 | } while (list); | |
1106 | } | |
1107 | ||
1108 | /** | |
1109 | * rhashtable_free_and_destroy - free elements and destroy hash table | |
1110 | * @ht: the hash table to destroy | |
1111 | * @free_fn: callback to release resources of element | |
1112 | * @arg: pointer passed to free_fn | |
1113 | * | |
1114 | * Stops an eventual async resize. If defined, invokes free_fn for each | |
1115 | * element to releasal resources. Please note that RCU protected | |
1116 | * readers may still be accessing the elements. Releasing of resources | |
1117 | * must occur in a compatible manner. Then frees the bucket array. | |
1118 | * | |
1119 | * This function will eventually sleep to wait for an async resize | |
1120 | * to complete. The caller is responsible that no further write operations | |
1121 | * occurs in parallel. | |
1122 | */ | |
1123 | void rhashtable_free_and_destroy(struct rhashtable *ht, | |
1124 | void (*free_fn)(void *ptr, void *arg), | |
1125 | void *arg) | |
1126 | { | |
1127 | struct bucket_table *tbl, *next_tbl; | |
1128 | unsigned int i; | |
1129 | ||
1130 | cancel_work_sync(&ht->run_work); | |
1131 | ||
1132 | mutex_lock(&ht->mutex); | |
1133 | tbl = rht_dereference(ht->tbl, ht); | |
1134 | restart: | |
1135 | if (free_fn) { | |
1136 | for (i = 0; i < tbl->size; i++) { | |
1137 | struct rhash_head *pos, *next; | |
1138 | ||
1139 | cond_resched(); | |
1140 | for (pos = rht_ptr_exclusive(rht_bucket(tbl, i)), | |
1141 | next = !rht_is_a_nulls(pos) ? | |
1142 | rht_dereference(pos->next, ht) : NULL; | |
1143 | !rht_is_a_nulls(pos); | |
1144 | pos = next, | |
1145 | next = !rht_is_a_nulls(pos) ? | |
1146 | rht_dereference(pos->next, ht) : NULL) | |
1147 | rhashtable_free_one(ht, pos, free_fn, arg); | |
1148 | } | |
1149 | } | |
1150 | ||
1151 | next_tbl = rht_dereference(tbl->future_tbl, ht); | |
1152 | bucket_table_free(tbl); | |
1153 | if (next_tbl) { | |
1154 | tbl = next_tbl; | |
1155 | goto restart; | |
1156 | } | |
1157 | mutex_unlock(&ht->mutex); | |
1158 | } | |
1159 | EXPORT_SYMBOL_GPL(rhashtable_free_and_destroy); | |
1160 | ||
1161 | void rhashtable_destroy(struct rhashtable *ht) | |
1162 | { | |
1163 | return rhashtable_free_and_destroy(ht, NULL, NULL); | |
1164 | } | |
1165 | EXPORT_SYMBOL_GPL(rhashtable_destroy); | |
1166 | ||
1167 | struct rhash_lock_head **__rht_bucket_nested(const struct bucket_table *tbl, | |
1168 | unsigned int hash) | |
1169 | { | |
1170 | const unsigned int shift = PAGE_SHIFT - ilog2(sizeof(void *)); | |
1171 | unsigned int index = hash & ((1 << tbl->nest) - 1); | |
1172 | unsigned int size = tbl->size >> tbl->nest; | |
1173 | unsigned int subhash = hash; | |
1174 | union nested_table *ntbl; | |
1175 | ||
1176 | ntbl = (union nested_table *)rcu_dereference_raw(tbl->buckets[0]); | |
1177 | ntbl = rht_dereference_bucket_rcu(ntbl[index].table, tbl, hash); | |
1178 | subhash >>= tbl->nest; | |
1179 | ||
1180 | while (ntbl && size > (1 << shift)) { | |
1181 | index = subhash & ((1 << shift) - 1); | |
1182 | ntbl = rht_dereference_bucket_rcu(ntbl[index].table, | |
1183 | tbl, hash); | |
1184 | size >>= shift; | |
1185 | subhash >>= shift; | |
1186 | } | |
1187 | ||
1188 | if (!ntbl) | |
1189 | return NULL; | |
1190 | ||
1191 | return &ntbl[subhash].bucket; | |
1192 | ||
1193 | } | |
1194 | EXPORT_SYMBOL_GPL(__rht_bucket_nested); | |
1195 | ||
1196 | struct rhash_lock_head **rht_bucket_nested(const struct bucket_table *tbl, | |
1197 | unsigned int hash) | |
1198 | { | |
1199 | static struct rhash_lock_head *rhnull; | |
1200 | ||
1201 | if (!rhnull) | |
1202 | INIT_RHT_NULLS_HEAD(rhnull); | |
1203 | return __rht_bucket_nested(tbl, hash) ?: &rhnull; | |
1204 | } | |
1205 | EXPORT_SYMBOL_GPL(rht_bucket_nested); | |
1206 | ||
1207 | struct rhash_lock_head **rht_bucket_nested_insert(struct rhashtable *ht, | |
1208 | struct bucket_table *tbl, | |
1209 | unsigned int hash) | |
1210 | { | |
1211 | const unsigned int shift = PAGE_SHIFT - ilog2(sizeof(void *)); | |
1212 | unsigned int index = hash & ((1 << tbl->nest) - 1); | |
1213 | unsigned int size = tbl->size >> tbl->nest; | |
1214 | union nested_table *ntbl; | |
1215 | ||
1216 | ntbl = (union nested_table *)rcu_dereference_raw(tbl->buckets[0]); | |
1217 | hash >>= tbl->nest; | |
1218 | ntbl = nested_table_alloc(ht, &ntbl[index].table, | |
1219 | size <= (1 << shift)); | |
1220 | ||
1221 | while (ntbl && size > (1 << shift)) { | |
1222 | index = hash & ((1 << shift) - 1); | |
1223 | size >>= shift; | |
1224 | hash >>= shift; | |
1225 | ntbl = nested_table_alloc(ht, &ntbl[index].table, | |
1226 | size <= (1 << shift)); | |
1227 | } | |
1228 | ||
1229 | if (!ntbl) | |
1230 | return NULL; | |
1231 | ||
1232 | return &ntbl[hash].bucket; | |
1233 | ||
1234 | } | |
1235 | EXPORT_SYMBOL_GPL(rht_bucket_nested_insert); |