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7e1e7763 TG |
1 | /* |
2 | * Resizable, Scalable, Concurrent Hash Table | |
3 | * | |
4 | * Copyright (c) 2014 Thomas Graf <tgraf@suug.ch> | |
5 | * Copyright (c) 2008-2014 Patrick McHardy <kaber@trash.net> | |
6 | * | |
7 | * Based on the following paper: | |
8 | * https://www.usenix.org/legacy/event/atc11/tech/final_files/Triplett.pdf | |
9 | * | |
10 | * Code partially derived from nft_hash | |
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 | #include <linux/kernel.h> | |
18 | #include <linux/init.h> | |
19 | #include <linux/log2.h> | |
20 | #include <linux/slab.h> | |
21 | #include <linux/vmalloc.h> | |
22 | #include <linux/mm.h> | |
87545899 | 23 | #include <linux/jhash.h> |
7e1e7763 TG |
24 | #include <linux/random.h> |
25 | #include <linux/rhashtable.h> | |
7e1e7763 TG |
26 | |
27 | #define HASH_DEFAULT_SIZE 64UL | |
28 | #define HASH_MIN_SIZE 4UL | |
29 | ||
30 | #define ASSERT_RHT_MUTEX(HT) BUG_ON(!lockdep_rht_mutex_is_held(HT)) | |
31 | ||
32 | #ifdef CONFIG_PROVE_LOCKING | |
33 | int lockdep_rht_mutex_is_held(const struct rhashtable *ht) | |
34 | { | |
7b4ce235 | 35 | return ht->p.mutex_is_held(ht->p.parent); |
7e1e7763 TG |
36 | } |
37 | EXPORT_SYMBOL_GPL(lockdep_rht_mutex_is_held); | |
38 | #endif | |
39 | ||
c91eee56 | 40 | static void *rht_obj(const struct rhashtable *ht, const struct rhash_head *he) |
7e1e7763 TG |
41 | { |
42 | return (void *) he - ht->p.head_offset; | |
43 | } | |
7e1e7763 TG |
44 | |
45 | static u32 __hashfn(const struct rhashtable *ht, const void *key, | |
46 | u32 len, u32 hsize) | |
47 | { | |
48 | u32 h; | |
49 | ||
50 | h = ht->p.hashfn(key, len, ht->p.hash_rnd); | |
51 | ||
52 | return h & (hsize - 1); | |
53 | } | |
54 | ||
55 | /** | |
56 | * rhashtable_hashfn - compute hash for key of given length | |
45d5acd3 | 57 | * @ht: hash table to compute for |
7e1e7763 TG |
58 | * @key: pointer to key |
59 | * @len: length of key | |
60 | * | |
61 | * Computes the hash value using the hash function provided in the 'hashfn' | |
62 | * of struct rhashtable_params. The returned value is guaranteed to be | |
63 | * smaller than the number of buckets in the hash table. | |
64 | */ | |
65 | u32 rhashtable_hashfn(const struct rhashtable *ht, const void *key, u32 len) | |
66 | { | |
67 | struct bucket_table *tbl = rht_dereference_rcu(ht->tbl, ht); | |
68 | ||
69 | return __hashfn(ht, key, len, tbl->size); | |
70 | } | |
71 | EXPORT_SYMBOL_GPL(rhashtable_hashfn); | |
72 | ||
73 | static u32 obj_hashfn(const struct rhashtable *ht, const void *ptr, u32 hsize) | |
74 | { | |
75 | if (unlikely(!ht->p.key_len)) { | |
76 | u32 h; | |
77 | ||
78 | h = ht->p.obj_hashfn(ptr, ht->p.hash_rnd); | |
79 | ||
80 | return h & (hsize - 1); | |
81 | } | |
82 | ||
83 | return __hashfn(ht, ptr + ht->p.key_offset, ht->p.key_len, hsize); | |
84 | } | |
85 | ||
86 | /** | |
87 | * rhashtable_obj_hashfn - compute hash for hashed object | |
45d5acd3 | 88 | * @ht: hash table to compute for |
7e1e7763 TG |
89 | * @ptr: pointer to hashed object |
90 | * | |
91 | * Computes the hash value using the hash function `hashfn` respectively | |
92 | * 'obj_hashfn' depending on whether the hash table is set up to work with | |
93 | * a fixed length key. The returned value is guaranteed to be smaller than | |
94 | * the number of buckets in the hash table. | |
95 | */ | |
96 | u32 rhashtable_obj_hashfn(const struct rhashtable *ht, void *ptr) | |
97 | { | |
98 | struct bucket_table *tbl = rht_dereference_rcu(ht->tbl, ht); | |
99 | ||
100 | return obj_hashfn(ht, ptr, tbl->size); | |
101 | } | |
102 | EXPORT_SYMBOL_GPL(rhashtable_obj_hashfn); | |
103 | ||
104 | static u32 head_hashfn(const struct rhashtable *ht, | |
105 | const struct rhash_head *he, u32 hsize) | |
106 | { | |
107 | return obj_hashfn(ht, rht_obj(ht, he), hsize); | |
108 | } | |
109 | ||
6eba8224 | 110 | static struct bucket_table *bucket_table_alloc(size_t nbuckets) |
7e1e7763 TG |
111 | { |
112 | struct bucket_table *tbl; | |
113 | size_t size; | |
114 | ||
115 | size = sizeof(*tbl) + nbuckets * sizeof(tbl->buckets[0]); | |
6eba8224 | 116 | tbl = kzalloc(size, GFP_KERNEL | __GFP_NOWARN); |
7e1e7763 TG |
117 | if (tbl == NULL) |
118 | tbl = vzalloc(size); | |
119 | ||
120 | if (tbl == NULL) | |
121 | return NULL; | |
122 | ||
123 | tbl->size = nbuckets; | |
124 | ||
125 | return tbl; | |
126 | } | |
127 | ||
128 | static void bucket_table_free(const struct bucket_table *tbl) | |
129 | { | |
130 | kvfree(tbl); | |
131 | } | |
132 | ||
133 | /** | |
134 | * rht_grow_above_75 - returns true if nelems > 0.75 * table-size | |
135 | * @ht: hash table | |
136 | * @new_size: new table size | |
137 | */ | |
138 | bool rht_grow_above_75(const struct rhashtable *ht, size_t new_size) | |
139 | { | |
140 | /* Expand table when exceeding 75% load */ | |
141 | return ht->nelems > (new_size / 4 * 3); | |
142 | } | |
143 | EXPORT_SYMBOL_GPL(rht_grow_above_75); | |
144 | ||
145 | /** | |
146 | * rht_shrink_below_30 - returns true if nelems < 0.3 * table-size | |
147 | * @ht: hash table | |
148 | * @new_size: new table size | |
149 | */ | |
150 | bool rht_shrink_below_30(const struct rhashtable *ht, size_t new_size) | |
151 | { | |
152 | /* Shrink table beneath 30% load */ | |
153 | return ht->nelems < (new_size * 3 / 10); | |
154 | } | |
155 | EXPORT_SYMBOL_GPL(rht_shrink_below_30); | |
156 | ||
157 | static void hashtable_chain_unzip(const struct rhashtable *ht, | |
158 | const struct bucket_table *new_tbl, | |
159 | struct bucket_table *old_tbl, size_t n) | |
160 | { | |
161 | struct rhash_head *he, *p, *next; | |
162 | unsigned int h; | |
163 | ||
164 | /* Old bucket empty, no work needed. */ | |
165 | p = rht_dereference(old_tbl->buckets[n], ht); | |
166 | if (!p) | |
167 | return; | |
168 | ||
169 | /* Advance the old bucket pointer one or more times until it | |
170 | * reaches a node that doesn't hash to the same bucket as the | |
171 | * previous node p. Call the previous node p; | |
172 | */ | |
173 | h = head_hashfn(ht, p, new_tbl->size); | |
174 | rht_for_each(he, p->next, ht) { | |
175 | if (head_hashfn(ht, he, new_tbl->size) != h) | |
176 | break; | |
177 | p = he; | |
178 | } | |
179 | RCU_INIT_POINTER(old_tbl->buckets[n], p->next); | |
180 | ||
181 | /* Find the subsequent node which does hash to the same | |
182 | * bucket as node P, or NULL if no such node exists. | |
183 | */ | |
184 | next = NULL; | |
185 | if (he) { | |
186 | rht_for_each(he, he->next, ht) { | |
187 | if (head_hashfn(ht, he, new_tbl->size) == h) { | |
188 | next = he; | |
189 | break; | |
190 | } | |
191 | } | |
192 | } | |
193 | ||
194 | /* Set p's next pointer to that subsequent node pointer, | |
195 | * bypassing the nodes which do not hash to p's bucket | |
196 | */ | |
197 | RCU_INIT_POINTER(p->next, next); | |
198 | } | |
199 | ||
200 | /** | |
201 | * rhashtable_expand - Expand hash table while allowing concurrent lookups | |
202 | * @ht: the hash table to expand | |
7e1e7763 TG |
203 | * |
204 | * A secondary bucket array is allocated and the hash entries are migrated | |
205 | * while keeping them on both lists until the end of the RCU grace period. | |
206 | * | |
207 | * This function may only be called in a context where it is safe to call | |
208 | * synchronize_rcu(), e.g. not within a rcu_read_lock() section. | |
209 | * | |
210 | * The caller must ensure that no concurrent table mutations take place. | |
211 | * It is however valid to have concurrent lookups if they are RCU protected. | |
212 | */ | |
6eba8224 | 213 | int rhashtable_expand(struct rhashtable *ht) |
7e1e7763 TG |
214 | { |
215 | struct bucket_table *new_tbl, *old_tbl = rht_dereference(ht->tbl, ht); | |
216 | struct rhash_head *he; | |
217 | unsigned int i, h; | |
218 | bool complete; | |
219 | ||
220 | ASSERT_RHT_MUTEX(ht); | |
221 | ||
222 | if (ht->p.max_shift && ht->shift >= ht->p.max_shift) | |
223 | return 0; | |
224 | ||
6eba8224 | 225 | new_tbl = bucket_table_alloc(old_tbl->size * 2); |
7e1e7763 TG |
226 | if (new_tbl == NULL) |
227 | return -ENOMEM; | |
228 | ||
229 | ht->shift++; | |
230 | ||
231 | /* For each new bucket, search the corresponding old bucket | |
0c828f2f | 232 | * for the first entry that hashes to the new bucket, and |
7e1e7763 TG |
233 | * link the new bucket to that entry. Since all the entries |
234 | * which will end up in the new bucket appear in the same | |
235 | * old bucket, this constructs an entirely valid new hash | |
236 | * table, but with multiple buckets "zipped" together into a | |
237 | * single imprecise chain. | |
238 | */ | |
239 | for (i = 0; i < new_tbl->size; i++) { | |
240 | h = i & (old_tbl->size - 1); | |
241 | rht_for_each(he, old_tbl->buckets[h], ht) { | |
242 | if (head_hashfn(ht, he, new_tbl->size) == i) { | |
243 | RCU_INIT_POINTER(new_tbl->buckets[i], he); | |
244 | break; | |
245 | } | |
246 | } | |
247 | } | |
248 | ||
249 | /* Publish the new table pointer. Lookups may now traverse | |
0c828f2f HX |
250 | * the new table, but they will not benefit from any |
251 | * additional efficiency until later steps unzip the buckets. | |
7e1e7763 TG |
252 | */ |
253 | rcu_assign_pointer(ht->tbl, new_tbl); | |
254 | ||
255 | /* Unzip interleaved hash chains */ | |
256 | do { | |
257 | /* Wait for readers. All new readers will see the new | |
258 | * table, and thus no references to the old table will | |
259 | * remain. | |
260 | */ | |
261 | synchronize_rcu(); | |
262 | ||
263 | /* For each bucket in the old table (each of which | |
264 | * contains items from multiple buckets of the new | |
265 | * table): ... | |
266 | */ | |
267 | complete = true; | |
268 | for (i = 0; i < old_tbl->size; i++) { | |
269 | hashtable_chain_unzip(ht, new_tbl, old_tbl, i); | |
270 | if (old_tbl->buckets[i] != NULL) | |
271 | complete = false; | |
272 | } | |
273 | } while (!complete); | |
274 | ||
275 | bucket_table_free(old_tbl); | |
276 | return 0; | |
277 | } | |
278 | EXPORT_SYMBOL_GPL(rhashtable_expand); | |
279 | ||
280 | /** | |
281 | * rhashtable_shrink - Shrink hash table while allowing concurrent lookups | |
282 | * @ht: the hash table to shrink | |
7e1e7763 TG |
283 | * |
284 | * This function may only be called in a context where it is safe to call | |
285 | * synchronize_rcu(), e.g. not within a rcu_read_lock() section. | |
286 | * | |
287 | * The caller must ensure that no concurrent table mutations take place. | |
288 | * It is however valid to have concurrent lookups if they are RCU protected. | |
289 | */ | |
6eba8224 | 290 | int rhashtable_shrink(struct rhashtable *ht) |
7e1e7763 TG |
291 | { |
292 | struct bucket_table *ntbl, *tbl = rht_dereference(ht->tbl, ht); | |
293 | struct rhash_head __rcu **pprev; | |
294 | unsigned int i; | |
295 | ||
296 | ASSERT_RHT_MUTEX(ht); | |
297 | ||
94000176 | 298 | if (ht->shift <= ht->p.min_shift) |
7e1e7763 TG |
299 | return 0; |
300 | ||
6eba8224 | 301 | ntbl = bucket_table_alloc(tbl->size / 2); |
7e1e7763 TG |
302 | if (ntbl == NULL) |
303 | return -ENOMEM; | |
304 | ||
305 | ht->shift--; | |
306 | ||
0c828f2f | 307 | /* Link each bucket in the new table to the first bucket |
7e1e7763 TG |
308 | * in the old table that contains entries which will hash |
309 | * to the new bucket. | |
310 | */ | |
311 | for (i = 0; i < ntbl->size; i++) { | |
312 | ntbl->buckets[i] = tbl->buckets[i]; | |
313 | ||
0c828f2f | 314 | /* Link each bucket in the new table to the first bucket |
7e1e7763 TG |
315 | * in the old table that contains entries which will hash |
316 | * to the new bucket. | |
317 | */ | |
318 | for (pprev = &ntbl->buckets[i]; *pprev != NULL; | |
319 | pprev = &rht_dereference(*pprev, ht)->next) | |
320 | ; | |
321 | RCU_INIT_POINTER(*pprev, tbl->buckets[i + ntbl->size]); | |
322 | } | |
323 | ||
324 | /* Publish the new, valid hash table */ | |
325 | rcu_assign_pointer(ht->tbl, ntbl); | |
326 | ||
327 | /* Wait for readers. No new readers will have references to the | |
328 | * old hash table. | |
329 | */ | |
330 | synchronize_rcu(); | |
331 | ||
332 | bucket_table_free(tbl); | |
333 | ||
334 | return 0; | |
335 | } | |
336 | EXPORT_SYMBOL_GPL(rhashtable_shrink); | |
337 | ||
338 | /** | |
339 | * rhashtable_insert - insert object into hash hash table | |
340 | * @ht: hash table | |
341 | * @obj: pointer to hash head inside object | |
7e1e7763 TG |
342 | * |
343 | * Will automatically grow the table via rhashtable_expand() if the the | |
344 | * grow_decision function specified at rhashtable_init() returns true. | |
345 | * | |
346 | * The caller must ensure that no concurrent table mutations occur. It is | |
347 | * however valid to have concurrent lookups if they are RCU protected. | |
348 | */ | |
6eba8224 | 349 | void rhashtable_insert(struct rhashtable *ht, struct rhash_head *obj) |
7e1e7763 TG |
350 | { |
351 | struct bucket_table *tbl = rht_dereference(ht->tbl, ht); | |
352 | u32 hash; | |
353 | ||
354 | ASSERT_RHT_MUTEX(ht); | |
355 | ||
356 | hash = head_hashfn(ht, obj, tbl->size); | |
357 | RCU_INIT_POINTER(obj->next, tbl->buckets[hash]); | |
358 | rcu_assign_pointer(tbl->buckets[hash], obj); | |
359 | ht->nelems++; | |
360 | ||
361 | if (ht->p.grow_decision && ht->p.grow_decision(ht, tbl->size)) | |
6eba8224 | 362 | rhashtable_expand(ht); |
7e1e7763 TG |
363 | } |
364 | EXPORT_SYMBOL_GPL(rhashtable_insert); | |
365 | ||
366 | /** | |
367 | * rhashtable_remove_pprev - remove object from hash table given previous element | |
368 | * @ht: hash table | |
369 | * @obj: pointer to hash head inside object | |
370 | * @pprev: pointer to previous element | |
7e1e7763 TG |
371 | * |
372 | * Identical to rhashtable_remove() but caller is alreayd aware of the element | |
373 | * in front of the element to be deleted. This is in particular useful for | |
374 | * deletion when combined with walking or lookup. | |
375 | */ | |
376 | void rhashtable_remove_pprev(struct rhashtable *ht, struct rhash_head *obj, | |
6eba8224 | 377 | struct rhash_head __rcu **pprev) |
7e1e7763 TG |
378 | { |
379 | struct bucket_table *tbl = rht_dereference(ht->tbl, ht); | |
380 | ||
381 | ASSERT_RHT_MUTEX(ht); | |
382 | ||
383 | RCU_INIT_POINTER(*pprev, obj->next); | |
384 | ht->nelems--; | |
385 | ||
386 | if (ht->p.shrink_decision && | |
387 | ht->p.shrink_decision(ht, tbl->size)) | |
6eba8224 | 388 | rhashtable_shrink(ht); |
7e1e7763 TG |
389 | } |
390 | EXPORT_SYMBOL_GPL(rhashtable_remove_pprev); | |
391 | ||
392 | /** | |
393 | * rhashtable_remove - remove object from hash table | |
394 | * @ht: hash table | |
395 | * @obj: pointer to hash head inside object | |
7e1e7763 TG |
396 | * |
397 | * Since the hash chain is single linked, the removal operation needs to | |
398 | * walk the bucket chain upon removal. The removal operation is thus | |
399 | * considerable slow if the hash table is not correctly sized. | |
400 | * | |
401 | * Will automatically shrink the table via rhashtable_expand() if the the | |
402 | * shrink_decision function specified at rhashtable_init() returns true. | |
403 | * | |
404 | * The caller must ensure that no concurrent table mutations occur. It is | |
405 | * however valid to have concurrent lookups if they are RCU protected. | |
406 | */ | |
6eba8224 | 407 | bool rhashtable_remove(struct rhashtable *ht, struct rhash_head *obj) |
7e1e7763 TG |
408 | { |
409 | struct bucket_table *tbl = rht_dereference(ht->tbl, ht); | |
410 | struct rhash_head __rcu **pprev; | |
411 | struct rhash_head *he; | |
412 | u32 h; | |
413 | ||
414 | ASSERT_RHT_MUTEX(ht); | |
415 | ||
416 | h = head_hashfn(ht, obj, tbl->size); | |
417 | ||
418 | pprev = &tbl->buckets[h]; | |
419 | rht_for_each(he, tbl->buckets[h], ht) { | |
420 | if (he != obj) { | |
421 | pprev = &he->next; | |
422 | continue; | |
423 | } | |
424 | ||
6eba8224 | 425 | rhashtable_remove_pprev(ht, he, pprev); |
7e1e7763 TG |
426 | return true; |
427 | } | |
428 | ||
429 | return false; | |
430 | } | |
431 | EXPORT_SYMBOL_GPL(rhashtable_remove); | |
432 | ||
433 | /** | |
434 | * rhashtable_lookup - lookup key in hash table | |
435 | * @ht: hash table | |
436 | * @key: pointer to key | |
437 | * | |
438 | * Computes the hash value for the key and traverses the bucket chain looking | |
439 | * for a entry with an identical key. The first matching entry is returned. | |
440 | * | |
441 | * This lookup function may only be used for fixed key hash table (key_len | |
442 | * paramter set). It will BUG() if used inappropriately. | |
443 | * | |
444 | * Lookups may occur in parallel with hash mutations as long as the lookup is | |
445 | * guarded by rcu_read_lock(). The caller must take care of this. | |
446 | */ | |
447 | void *rhashtable_lookup(const struct rhashtable *ht, const void *key) | |
448 | { | |
449 | const struct bucket_table *tbl = rht_dereference_rcu(ht->tbl, ht); | |
450 | struct rhash_head *he; | |
451 | u32 h; | |
452 | ||
453 | BUG_ON(!ht->p.key_len); | |
454 | ||
455 | h = __hashfn(ht, key, ht->p.key_len, tbl->size); | |
456 | rht_for_each_rcu(he, tbl->buckets[h], ht) { | |
457 | if (memcmp(rht_obj(ht, he) + ht->p.key_offset, key, | |
458 | ht->p.key_len)) | |
459 | continue; | |
460 | return (void *) he - ht->p.head_offset; | |
461 | } | |
462 | ||
463 | return NULL; | |
464 | } | |
465 | EXPORT_SYMBOL_GPL(rhashtable_lookup); | |
466 | ||
467 | /** | |
468 | * rhashtable_lookup_compare - search hash table with compare function | |
469 | * @ht: hash table | |
470 | * @hash: hash value of desired entry | |
471 | * @compare: compare function, must return true on match | |
472 | * @arg: argument passed on to compare function | |
473 | * | |
474 | * Traverses the bucket chain behind the provided hash value and calls the | |
475 | * specified compare function for each entry. | |
476 | * | |
477 | * Lookups may occur in parallel with hash mutations as long as the lookup is | |
478 | * guarded by rcu_read_lock(). The caller must take care of this. | |
479 | * | |
480 | * Returns the first entry on which the compare function returned true. | |
481 | */ | |
482 | void *rhashtable_lookup_compare(const struct rhashtable *ht, u32 hash, | |
483 | bool (*compare)(void *, void *), void *arg) | |
484 | { | |
485 | const struct bucket_table *tbl = rht_dereference_rcu(ht->tbl, ht); | |
486 | struct rhash_head *he; | |
487 | ||
488 | if (unlikely(hash >= tbl->size)) | |
489 | return NULL; | |
490 | ||
491 | rht_for_each_rcu(he, tbl->buckets[hash], ht) { | |
492 | if (!compare(rht_obj(ht, he), arg)) | |
493 | continue; | |
494 | return (void *) he - ht->p.head_offset; | |
495 | } | |
496 | ||
497 | return NULL; | |
498 | } | |
499 | EXPORT_SYMBOL_GPL(rhashtable_lookup_compare); | |
500 | ||
94000176 | 501 | static size_t rounded_hashtable_size(struct rhashtable_params *params) |
7e1e7763 | 502 | { |
94000176 YX |
503 | return max(roundup_pow_of_two(params->nelem_hint * 4 / 3), |
504 | 1UL << params->min_shift); | |
7e1e7763 TG |
505 | } |
506 | ||
507 | /** | |
508 | * rhashtable_init - initialize a new hash table | |
509 | * @ht: hash table to be initialized | |
510 | * @params: configuration parameters | |
511 | * | |
512 | * Initializes a new hash table based on the provided configuration | |
513 | * parameters. A table can be configured either with a variable or | |
514 | * fixed length key: | |
515 | * | |
516 | * Configuration Example 1: Fixed length keys | |
517 | * struct test_obj { | |
518 | * int key; | |
519 | * void * my_member; | |
520 | * struct rhash_head node; | |
521 | * }; | |
522 | * | |
523 | * struct rhashtable_params params = { | |
524 | * .head_offset = offsetof(struct test_obj, node), | |
525 | * .key_offset = offsetof(struct test_obj, key), | |
526 | * .key_len = sizeof(int), | |
87545899 | 527 | * .hashfn = jhash, |
1b2f309d | 528 | * #ifdef CONFIG_PROVE_LOCKING |
7e1e7763 | 529 | * .mutex_is_held = &my_mutex_is_held, |
1b2f309d | 530 | * #endif |
7e1e7763 TG |
531 | * }; |
532 | * | |
533 | * Configuration Example 2: Variable length keys | |
534 | * struct test_obj { | |
535 | * [...] | |
536 | * struct rhash_head node; | |
537 | * }; | |
538 | * | |
539 | * u32 my_hash_fn(const void *data, u32 seed) | |
540 | * { | |
541 | * struct test_obj *obj = data; | |
542 | * | |
543 | * return [... hash ...]; | |
544 | * } | |
545 | * | |
546 | * struct rhashtable_params params = { | |
547 | * .head_offset = offsetof(struct test_obj, node), | |
87545899 | 548 | * .hashfn = jhash, |
7e1e7763 | 549 | * .obj_hashfn = my_hash_fn, |
1b2f309d | 550 | * #ifdef CONFIG_PROVE_LOCKING |
7e1e7763 | 551 | * .mutex_is_held = &my_mutex_is_held, |
1b2f309d | 552 | * #endif |
7e1e7763 TG |
553 | * }; |
554 | */ | |
555 | int rhashtable_init(struct rhashtable *ht, struct rhashtable_params *params) | |
556 | { | |
557 | struct bucket_table *tbl; | |
558 | size_t size; | |
559 | ||
560 | size = HASH_DEFAULT_SIZE; | |
561 | ||
562 | if ((params->key_len && !params->hashfn) || | |
563 | (!params->key_len && !params->obj_hashfn)) | |
564 | return -EINVAL; | |
565 | ||
94000176 YX |
566 | params->min_shift = max_t(size_t, params->min_shift, |
567 | ilog2(HASH_MIN_SIZE)); | |
568 | ||
7e1e7763 | 569 | if (params->nelem_hint) |
94000176 | 570 | size = rounded_hashtable_size(params); |
7e1e7763 | 571 | |
6eba8224 | 572 | tbl = bucket_table_alloc(size); |
7e1e7763 TG |
573 | if (tbl == NULL) |
574 | return -ENOMEM; | |
575 | ||
576 | memset(ht, 0, sizeof(*ht)); | |
577 | ht->shift = ilog2(tbl->size); | |
578 | memcpy(&ht->p, params, sizeof(*params)); | |
579 | RCU_INIT_POINTER(ht->tbl, tbl); | |
580 | ||
581 | if (!ht->p.hash_rnd) | |
582 | get_random_bytes(&ht->p.hash_rnd, sizeof(ht->p.hash_rnd)); | |
583 | ||
584 | return 0; | |
585 | } | |
586 | EXPORT_SYMBOL_GPL(rhashtable_init); | |
587 | ||
588 | /** | |
589 | * rhashtable_destroy - destroy hash table | |
590 | * @ht: the hash table to destroy | |
591 | * | |
ae82ddcf PNA |
592 | * Frees the bucket array. This function is not rcu safe, therefore the caller |
593 | * has to make sure that no resizing may happen by unpublishing the hashtable | |
594 | * and waiting for the quiescent cycle before releasing the bucket array. | |
7e1e7763 TG |
595 | */ |
596 | void rhashtable_destroy(const struct rhashtable *ht) | |
597 | { | |
ae82ddcf | 598 | bucket_table_free(ht->tbl); |
7e1e7763 TG |
599 | } |
600 | EXPORT_SYMBOL_GPL(rhashtable_destroy); | |
601 | ||
602 | /************************************************************************** | |
603 | * Self Test | |
604 | **************************************************************************/ | |
605 | ||
606 | #ifdef CONFIG_TEST_RHASHTABLE | |
607 | ||
608 | #define TEST_HT_SIZE 8 | |
609 | #define TEST_ENTRIES 2048 | |
610 | #define TEST_PTR ((void *) 0xdeadbeef) | |
611 | #define TEST_NEXPANDS 4 | |
612 | ||
1b2f309d | 613 | #ifdef CONFIG_PROVE_LOCKING |
7b4ce235 | 614 | static int test_mutex_is_held(void *parent) |
7e1e7763 TG |
615 | { |
616 | return 1; | |
617 | } | |
1b2f309d | 618 | #endif |
7e1e7763 TG |
619 | |
620 | struct test_obj { | |
621 | void *ptr; | |
622 | int value; | |
623 | struct rhash_head node; | |
624 | }; | |
625 | ||
626 | static int __init test_rht_lookup(struct rhashtable *ht) | |
627 | { | |
628 | unsigned int i; | |
629 | ||
630 | for (i = 0; i < TEST_ENTRIES * 2; i++) { | |
631 | struct test_obj *obj; | |
632 | bool expected = !(i % 2); | |
633 | u32 key = i; | |
634 | ||
635 | obj = rhashtable_lookup(ht, &key); | |
636 | ||
637 | if (expected && !obj) { | |
638 | pr_warn("Test failed: Could not find key %u\n", key); | |
639 | return -ENOENT; | |
640 | } else if (!expected && obj) { | |
641 | pr_warn("Test failed: Unexpected entry found for key %u\n", | |
642 | key); | |
643 | return -EEXIST; | |
644 | } else if (expected && obj) { | |
645 | if (obj->ptr != TEST_PTR || obj->value != i) { | |
646 | pr_warn("Test failed: Lookup value mismatch %p!=%p, %u!=%u\n", | |
647 | obj->ptr, TEST_PTR, obj->value, i); | |
648 | return -EINVAL; | |
649 | } | |
650 | } | |
651 | } | |
652 | ||
653 | return 0; | |
654 | } | |
655 | ||
3e7b2ec4 | 656 | static void test_bucket_stats(struct rhashtable *ht, bool quiet) |
7e1e7763 | 657 | { |
3e7b2ec4 | 658 | unsigned int cnt, rcu_cnt, i, total = 0; |
7e1e7763 | 659 | struct test_obj *obj; |
3e7b2ec4 | 660 | struct bucket_table *tbl; |
7e1e7763 | 661 | |
3e7b2ec4 | 662 | tbl = rht_dereference_rcu(ht->tbl, ht); |
7e1e7763 | 663 | for (i = 0; i < tbl->size; i++) { |
3e7b2ec4 | 664 | rcu_cnt = cnt = 0; |
7e1e7763 TG |
665 | |
666 | if (!quiet) | |
667 | pr_info(" [%#4x/%zu]", i, tbl->size); | |
668 | ||
669 | rht_for_each_entry_rcu(obj, tbl->buckets[i], node) { | |
670 | cnt++; | |
671 | total++; | |
672 | if (!quiet) | |
673 | pr_cont(" [%p],", obj); | |
674 | } | |
675 | ||
3e7b2ec4 TG |
676 | rht_for_each_entry_rcu(obj, tbl->buckets[i], node) |
677 | rcu_cnt++; | |
678 | ||
679 | if (rcu_cnt != cnt) | |
680 | pr_warn("Test failed: Chain count mismach %d != %d", | |
681 | cnt, rcu_cnt); | |
682 | ||
7e1e7763 TG |
683 | if (!quiet) |
684 | pr_cont("\n [%#x] first element: %p, chain length: %u\n", | |
685 | i, tbl->buckets[i], cnt); | |
686 | } | |
687 | ||
688 | pr_info(" Traversal complete: counted=%u, nelems=%zu, entries=%d\n", | |
689 | total, ht->nelems, TEST_ENTRIES); | |
3e7b2ec4 TG |
690 | |
691 | if (total != ht->nelems || total != TEST_ENTRIES) | |
692 | pr_warn("Test failed: Total count mismatch ^^^"); | |
7e1e7763 TG |
693 | } |
694 | ||
695 | static int __init test_rhashtable(struct rhashtable *ht) | |
696 | { | |
697 | struct bucket_table *tbl; | |
698 | struct test_obj *obj, *next; | |
699 | int err; | |
700 | unsigned int i; | |
701 | ||
702 | /* | |
703 | * Insertion Test: | |
704 | * Insert TEST_ENTRIES into table with all keys even numbers | |
705 | */ | |
706 | pr_info(" Adding %d keys\n", TEST_ENTRIES); | |
707 | for (i = 0; i < TEST_ENTRIES; i++) { | |
708 | struct test_obj *obj; | |
709 | ||
710 | obj = kzalloc(sizeof(*obj), GFP_KERNEL); | |
711 | if (!obj) { | |
712 | err = -ENOMEM; | |
713 | goto error; | |
714 | } | |
715 | ||
716 | obj->ptr = TEST_PTR; | |
717 | obj->value = i * 2; | |
718 | ||
6eba8224 | 719 | rhashtable_insert(ht, &obj->node); |
7e1e7763 TG |
720 | } |
721 | ||
722 | rcu_read_lock(); | |
3e7b2ec4 | 723 | test_bucket_stats(ht, true); |
7e1e7763 TG |
724 | test_rht_lookup(ht); |
725 | rcu_read_unlock(); | |
726 | ||
727 | for (i = 0; i < TEST_NEXPANDS; i++) { | |
728 | pr_info(" Table expansion iteration %u...\n", i); | |
6eba8224 | 729 | rhashtable_expand(ht); |
7e1e7763 TG |
730 | |
731 | rcu_read_lock(); | |
732 | pr_info(" Verifying lookups...\n"); | |
733 | test_rht_lookup(ht); | |
734 | rcu_read_unlock(); | |
735 | } | |
736 | ||
737 | for (i = 0; i < TEST_NEXPANDS; i++) { | |
738 | pr_info(" Table shrinkage iteration %u...\n", i); | |
6eba8224 | 739 | rhashtable_shrink(ht); |
7e1e7763 TG |
740 | |
741 | rcu_read_lock(); | |
742 | pr_info(" Verifying lookups...\n"); | |
743 | test_rht_lookup(ht); | |
744 | rcu_read_unlock(); | |
745 | } | |
746 | ||
3e7b2ec4 TG |
747 | rcu_read_lock(); |
748 | test_bucket_stats(ht, true); | |
749 | rcu_read_unlock(); | |
750 | ||
7e1e7763 TG |
751 | pr_info(" Deleting %d keys\n", TEST_ENTRIES); |
752 | for (i = 0; i < TEST_ENTRIES; i++) { | |
753 | u32 key = i * 2; | |
754 | ||
755 | obj = rhashtable_lookup(ht, &key); | |
756 | BUG_ON(!obj); | |
757 | ||
6eba8224 | 758 | rhashtable_remove(ht, &obj->node); |
7e1e7763 TG |
759 | kfree(obj); |
760 | } | |
761 | ||
762 | return 0; | |
763 | ||
764 | error: | |
765 | tbl = rht_dereference_rcu(ht->tbl, ht); | |
766 | for (i = 0; i < tbl->size; i++) | |
767 | rht_for_each_entry_safe(obj, next, tbl->buckets[i], ht, node) | |
768 | kfree(obj); | |
769 | ||
770 | return err; | |
771 | } | |
772 | ||
773 | static int __init test_rht_init(void) | |
774 | { | |
775 | struct rhashtable ht; | |
776 | struct rhashtable_params params = { | |
777 | .nelem_hint = TEST_HT_SIZE, | |
778 | .head_offset = offsetof(struct test_obj, node), | |
779 | .key_offset = offsetof(struct test_obj, value), | |
780 | .key_len = sizeof(int), | |
87545899 | 781 | .hashfn = jhash, |
1b2f309d | 782 | #ifdef CONFIG_PROVE_LOCKING |
7e1e7763 | 783 | .mutex_is_held = &test_mutex_is_held, |
1b2f309d | 784 | #endif |
7e1e7763 TG |
785 | .grow_decision = rht_grow_above_75, |
786 | .shrink_decision = rht_shrink_below_30, | |
787 | }; | |
788 | int err; | |
789 | ||
790 | pr_info("Running resizable hashtable tests...\n"); | |
791 | ||
792 | err = rhashtable_init(&ht, ¶ms); | |
793 | if (err < 0) { | |
794 | pr_warn("Test failed: Unable to initialize hashtable: %d\n", | |
795 | err); | |
796 | return err; | |
797 | } | |
798 | ||
799 | err = test_rhashtable(&ht); | |
800 | ||
801 | rhashtable_destroy(&ht); | |
802 | ||
803 | return err; | |
804 | } | |
805 | ||
806 | subsys_initcall(test_rht_init); | |
807 | ||
808 | #endif /* CONFIG_TEST_RHASHTABLE */ |