Commit | Line | Data |
---|---|---|
7e1e7763 TG |
1 | /* |
2 | * Resizable, Scalable, Concurrent Hash Table | |
3 | * | |
02fd97c3 | 4 | * Copyright (c) 2015 Herbert Xu <herbert@gondor.apana.org.au> |
a5ec68e3 | 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 |
02fd97c3 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 | ||
07ee0722 | 17 | #include <linux/atomic.h> |
7e1e7763 TG |
18 | #include <linux/kernel.h> |
19 | #include <linux/init.h> | |
20 | #include <linux/log2.h> | |
5beb5c90 | 21 | #include <linux/sched.h> |
7e1e7763 TG |
22 | #include <linux/slab.h> |
23 | #include <linux/vmalloc.h> | |
24 | #include <linux/mm.h> | |
87545899 | 25 | #include <linux/jhash.h> |
7e1e7763 TG |
26 | #include <linux/random.h> |
27 | #include <linux/rhashtable.h> | |
61d7b097 | 28 | #include <linux/err.h> |
6d795413 | 29 | #include <linux/export.h> |
7e1e7763 TG |
30 | |
31 | #define HASH_DEFAULT_SIZE 64UL | |
c2e213cf | 32 | #define HASH_MIN_SIZE 4U |
4cf0b354 | 33 | #define BUCKET_LOCKS_PER_CPU 32UL |
97defe1e | 34 | |
988dfbd7 | 35 | static u32 head_hashfn(struct rhashtable *ht, |
8d24c0b4 TG |
36 | const struct bucket_table *tbl, |
37 | const struct rhash_head *he) | |
7e1e7763 | 38 | { |
02fd97c3 | 39 | return rht_head_hashfn(ht, tbl, he, ht->p); |
7e1e7763 TG |
40 | } |
41 | ||
a03eaec0 | 42 | #ifdef CONFIG_PROVE_LOCKING |
a03eaec0 | 43 | #define ASSERT_RHT_MUTEX(HT) BUG_ON(!lockdep_rht_mutex_is_held(HT)) |
a03eaec0 TG |
44 | |
45 | int lockdep_rht_mutex_is_held(struct rhashtable *ht) | |
46 | { | |
47 | return (debug_locks) ? lockdep_is_held(&ht->mutex) : 1; | |
48 | } | |
49 | EXPORT_SYMBOL_GPL(lockdep_rht_mutex_is_held); | |
50 | ||
51 | int lockdep_rht_bucket_is_held(const struct bucket_table *tbl, u32 hash) | |
52 | { | |
02fd97c3 | 53 | spinlock_t *lock = rht_bucket_lock(tbl, hash); |
a03eaec0 TG |
54 | |
55 | return (debug_locks) ? lockdep_is_held(lock) : 1; | |
56 | } | |
57 | EXPORT_SYMBOL_GPL(lockdep_rht_bucket_is_held); | |
58 | #else | |
59 | #define ASSERT_RHT_MUTEX(HT) | |
a03eaec0 TG |
60 | #endif |
61 | ||
62 | ||
b9ecfdaa HX |
63 | static int alloc_bucket_locks(struct rhashtable *ht, struct bucket_table *tbl, |
64 | gfp_t gfp) | |
97defe1e TG |
65 | { |
66 | unsigned int i, size; | |
67 | #if defined(CONFIG_PROVE_LOCKING) | |
68 | unsigned int nr_pcpus = 2; | |
69 | #else | |
70 | unsigned int nr_pcpus = num_possible_cpus(); | |
71 | #endif | |
72 | ||
4cf0b354 | 73 | nr_pcpus = min_t(unsigned int, nr_pcpus, 64UL); |
97defe1e TG |
74 | size = roundup_pow_of_two(nr_pcpus * ht->p.locks_mul); |
75 | ||
a5ec68e3 TG |
76 | /* Never allocate more than 0.5 locks per bucket */ |
77 | size = min_t(unsigned int, size, tbl->size >> 1); | |
97defe1e TG |
78 | |
79 | if (sizeof(spinlock_t) != 0) { | |
9dbeea7f | 80 | tbl->locks = NULL; |
97defe1e | 81 | #ifdef CONFIG_NUMA |
b9ecfdaa HX |
82 | if (size * sizeof(spinlock_t) > PAGE_SIZE && |
83 | gfp == GFP_KERNEL) | |
97defe1e | 84 | tbl->locks = vmalloc(size * sizeof(spinlock_t)); |
97defe1e | 85 | #endif |
4cf0b354 FW |
86 | if (gfp != GFP_KERNEL) |
87 | gfp |= __GFP_NOWARN | __GFP_NORETRY; | |
88 | ||
9dbeea7f ED |
89 | if (!tbl->locks) |
90 | tbl->locks = kmalloc_array(size, sizeof(spinlock_t), | |
91 | gfp); | |
97defe1e TG |
92 | if (!tbl->locks) |
93 | return -ENOMEM; | |
94 | for (i = 0; i < size; i++) | |
95 | spin_lock_init(&tbl->locks[i]); | |
96 | } | |
97 | tbl->locks_mask = size - 1; | |
98 | ||
99 | return 0; | |
100 | } | |
101 | ||
102 | static void bucket_table_free(const struct bucket_table *tbl) | |
103 | { | |
104 | if (tbl) | |
105 | kvfree(tbl->locks); | |
106 | ||
107 | kvfree(tbl); | |
108 | } | |
109 | ||
9d901bc0 HX |
110 | static void bucket_table_free_rcu(struct rcu_head *head) |
111 | { | |
112 | bucket_table_free(container_of(head, struct bucket_table, rcu)); | |
113 | } | |
114 | ||
97defe1e | 115 | static struct bucket_table *bucket_table_alloc(struct rhashtable *ht, |
b9ecfdaa HX |
116 | size_t nbuckets, |
117 | gfp_t gfp) | |
7e1e7763 | 118 | { |
eb6d1abf | 119 | struct bucket_table *tbl = NULL; |
7e1e7763 | 120 | size_t size; |
f89bd6f8 | 121 | int i; |
7e1e7763 TG |
122 | |
123 | size = sizeof(*tbl) + nbuckets * sizeof(tbl->buckets[0]); | |
b9ecfdaa HX |
124 | if (size <= (PAGE_SIZE << PAGE_ALLOC_COSTLY_ORDER) || |
125 | gfp != GFP_KERNEL) | |
126 | tbl = kzalloc(size, gfp | __GFP_NOWARN | __GFP_NORETRY); | |
127 | if (tbl == NULL && gfp == GFP_KERNEL) | |
7e1e7763 | 128 | tbl = vzalloc(size); |
7e1e7763 TG |
129 | if (tbl == NULL) |
130 | return NULL; | |
131 | ||
132 | tbl->size = nbuckets; | |
133 | ||
b9ecfdaa | 134 | if (alloc_bucket_locks(ht, tbl, gfp) < 0) { |
97defe1e TG |
135 | bucket_table_free(tbl); |
136 | return NULL; | |
137 | } | |
7e1e7763 | 138 | |
eddee5ba HX |
139 | INIT_LIST_HEAD(&tbl->walkers); |
140 | ||
5269b53d HX |
141 | get_random_bytes(&tbl->hash_rnd, sizeof(tbl->hash_rnd)); |
142 | ||
f89bd6f8 TG |
143 | for (i = 0; i < nbuckets; i++) |
144 | INIT_RHT_NULLS_HEAD(tbl->buckets[i], ht, i); | |
145 | ||
97defe1e | 146 | return tbl; |
7e1e7763 TG |
147 | } |
148 | ||
b824478b HX |
149 | static struct bucket_table *rhashtable_last_table(struct rhashtable *ht, |
150 | struct bucket_table *tbl) | |
151 | { | |
152 | struct bucket_table *new_tbl; | |
153 | ||
154 | do { | |
155 | new_tbl = tbl; | |
156 | tbl = rht_dereference_rcu(tbl->future_tbl, ht); | |
157 | } while (tbl); | |
158 | ||
159 | return new_tbl; | |
160 | } | |
161 | ||
299e5c32 | 162 | static int rhashtable_rehash_one(struct rhashtable *ht, unsigned int old_hash) |
a5ec68e3 | 163 | { |
aa34a6cb | 164 | struct bucket_table *old_tbl = rht_dereference(ht->tbl, ht); |
b824478b HX |
165 | struct bucket_table *new_tbl = rhashtable_last_table(ht, |
166 | rht_dereference_rcu(old_tbl->future_tbl, ht)); | |
aa34a6cb HX |
167 | struct rhash_head __rcu **pprev = &old_tbl->buckets[old_hash]; |
168 | int err = -ENOENT; | |
169 | struct rhash_head *head, *next, *entry; | |
170 | spinlock_t *new_bucket_lock; | |
299e5c32 | 171 | unsigned int new_hash; |
aa34a6cb HX |
172 | |
173 | rht_for_each(entry, old_tbl, old_hash) { | |
174 | err = 0; | |
175 | next = rht_dereference_bucket(entry->next, old_tbl, old_hash); | |
176 | ||
177 | if (rht_is_a_nulls(next)) | |
178 | break; | |
a5ec68e3 | 179 | |
aa34a6cb HX |
180 | pprev = &entry->next; |
181 | } | |
a5ec68e3 | 182 | |
aa34a6cb HX |
183 | if (err) |
184 | goto out; | |
97defe1e | 185 | |
aa34a6cb | 186 | new_hash = head_hashfn(ht, new_tbl, entry); |
7e1e7763 | 187 | |
02fd97c3 | 188 | new_bucket_lock = rht_bucket_lock(new_tbl, new_hash); |
7e1e7763 | 189 | |
8f2484bd | 190 | spin_lock_nested(new_bucket_lock, SINGLE_DEPTH_NESTING); |
aa34a6cb HX |
191 | head = rht_dereference_bucket(new_tbl->buckets[new_hash], |
192 | new_tbl, new_hash); | |
97defe1e | 193 | |
7def0f95 | 194 | RCU_INIT_POINTER(entry->next, head); |
a5ec68e3 | 195 | |
aa34a6cb HX |
196 | rcu_assign_pointer(new_tbl->buckets[new_hash], entry); |
197 | spin_unlock(new_bucket_lock); | |
97defe1e | 198 | |
aa34a6cb | 199 | rcu_assign_pointer(*pprev, next); |
7e1e7763 | 200 | |
aa34a6cb HX |
201 | out: |
202 | return err; | |
203 | } | |
97defe1e | 204 | |
299e5c32 TG |
205 | static void rhashtable_rehash_chain(struct rhashtable *ht, |
206 | unsigned int old_hash) | |
aa34a6cb HX |
207 | { |
208 | struct bucket_table *old_tbl = rht_dereference(ht->tbl, ht); | |
209 | spinlock_t *old_bucket_lock; | |
210 | ||
02fd97c3 | 211 | old_bucket_lock = rht_bucket_lock(old_tbl, old_hash); |
a5ec68e3 | 212 | |
aa34a6cb HX |
213 | spin_lock_bh(old_bucket_lock); |
214 | while (!rhashtable_rehash_one(ht, old_hash)) | |
215 | ; | |
63d512d0 | 216 | old_tbl->rehash++; |
aa34a6cb | 217 | spin_unlock_bh(old_bucket_lock); |
97defe1e TG |
218 | } |
219 | ||
b824478b HX |
220 | static int rhashtable_rehash_attach(struct rhashtable *ht, |
221 | struct bucket_table *old_tbl, | |
222 | struct bucket_table *new_tbl) | |
97defe1e | 223 | { |
b824478b HX |
224 | /* Protect future_tbl using the first bucket lock. */ |
225 | spin_lock_bh(old_tbl->locks); | |
226 | ||
227 | /* Did somebody beat us to it? */ | |
228 | if (rcu_access_pointer(old_tbl->future_tbl)) { | |
229 | spin_unlock_bh(old_tbl->locks); | |
230 | return -EEXIST; | |
231 | } | |
7cd10db8 | 232 | |
aa34a6cb HX |
233 | /* Make insertions go into the new, empty table right away. Deletions |
234 | * and lookups will be attempted in both tables until we synchronize. | |
aa34a6cb | 235 | */ |
c4db8848 | 236 | rcu_assign_pointer(old_tbl->future_tbl, new_tbl); |
aa34a6cb | 237 | |
b824478b HX |
238 | spin_unlock_bh(old_tbl->locks); |
239 | ||
240 | return 0; | |
241 | } | |
242 | ||
243 | static int rhashtable_rehash_table(struct rhashtable *ht) | |
244 | { | |
245 | struct bucket_table *old_tbl = rht_dereference(ht->tbl, ht); | |
246 | struct bucket_table *new_tbl; | |
247 | struct rhashtable_walker *walker; | |
299e5c32 | 248 | unsigned int old_hash; |
b824478b HX |
249 | |
250 | new_tbl = rht_dereference(old_tbl->future_tbl, ht); | |
251 | if (!new_tbl) | |
252 | return 0; | |
253 | ||
aa34a6cb HX |
254 | for (old_hash = 0; old_hash < old_tbl->size; old_hash++) |
255 | rhashtable_rehash_chain(ht, old_hash); | |
256 | ||
257 | /* Publish the new table pointer. */ | |
258 | rcu_assign_pointer(ht->tbl, new_tbl); | |
259 | ||
ba7c95ea | 260 | spin_lock(&ht->lock); |
eddee5ba HX |
261 | list_for_each_entry(walker, &old_tbl->walkers, list) |
262 | walker->tbl = NULL; | |
ba7c95ea | 263 | spin_unlock(&ht->lock); |
eddee5ba | 264 | |
aa34a6cb HX |
265 | /* Wait for readers. All new readers will see the new |
266 | * table, and thus no references to the old table will | |
267 | * remain. | |
268 | */ | |
9d901bc0 | 269 | call_rcu(&old_tbl->rcu, bucket_table_free_rcu); |
b824478b HX |
270 | |
271 | return rht_dereference(new_tbl->future_tbl, ht) ? -EAGAIN : 0; | |
7e1e7763 TG |
272 | } |
273 | ||
274 | /** | |
275 | * rhashtable_expand - Expand hash table while allowing concurrent lookups | |
276 | * @ht: the hash table to expand | |
7e1e7763 | 277 | * |
aa34a6cb | 278 | * A secondary bucket array is allocated and the hash entries are migrated. |
7e1e7763 TG |
279 | * |
280 | * This function may only be called in a context where it is safe to call | |
281 | * synchronize_rcu(), e.g. not within a rcu_read_lock() section. | |
282 | * | |
97defe1e TG |
283 | * The caller must ensure that no concurrent resizing occurs by holding |
284 | * ht->mutex. | |
285 | * | |
286 | * It is valid to have concurrent insertions and deletions protected by per | |
287 | * bucket locks or concurrent RCU protected lookups and traversals. | |
7e1e7763 | 288 | */ |
b824478b | 289 | static int rhashtable_expand(struct rhashtable *ht) |
7e1e7763 TG |
290 | { |
291 | struct bucket_table *new_tbl, *old_tbl = rht_dereference(ht->tbl, ht); | |
b824478b | 292 | int err; |
7e1e7763 TG |
293 | |
294 | ASSERT_RHT_MUTEX(ht); | |
295 | ||
b824478b HX |
296 | old_tbl = rhashtable_last_table(ht, old_tbl); |
297 | ||
b9ecfdaa | 298 | new_tbl = bucket_table_alloc(ht, old_tbl->size * 2, GFP_KERNEL); |
7e1e7763 TG |
299 | if (new_tbl == NULL) |
300 | return -ENOMEM; | |
301 | ||
b824478b HX |
302 | err = rhashtable_rehash_attach(ht, old_tbl, new_tbl); |
303 | if (err) | |
304 | bucket_table_free(new_tbl); | |
305 | ||
306 | return err; | |
7e1e7763 | 307 | } |
7e1e7763 TG |
308 | |
309 | /** | |
310 | * rhashtable_shrink - Shrink hash table while allowing concurrent lookups | |
311 | * @ht: the hash table to shrink | |
7e1e7763 | 312 | * |
18093d1c HX |
313 | * This function shrinks the hash table to fit, i.e., the smallest |
314 | * size would not cause it to expand right away automatically. | |
7e1e7763 | 315 | * |
97defe1e TG |
316 | * The caller must ensure that no concurrent resizing occurs by holding |
317 | * ht->mutex. | |
318 | * | |
7e1e7763 TG |
319 | * The caller must ensure that no concurrent table mutations take place. |
320 | * It is however valid to have concurrent lookups if they are RCU protected. | |
97defe1e TG |
321 | * |
322 | * It is valid to have concurrent insertions and deletions protected by per | |
323 | * bucket locks or concurrent RCU protected lookups and traversals. | |
7e1e7763 | 324 | */ |
b824478b | 325 | static int rhashtable_shrink(struct rhashtable *ht) |
7e1e7763 | 326 | { |
a5b6846f | 327 | struct bucket_table *new_tbl, *old_tbl = rht_dereference(ht->tbl, ht); |
12311959 VN |
328 | unsigned int nelems = atomic_read(&ht->nelems); |
329 | unsigned int size = 0; | |
b824478b | 330 | int err; |
7e1e7763 TG |
331 | |
332 | ASSERT_RHT_MUTEX(ht); | |
333 | ||
12311959 VN |
334 | if (nelems) |
335 | size = roundup_pow_of_two(nelems * 3 / 2); | |
18093d1c HX |
336 | if (size < ht->p.min_size) |
337 | size = ht->p.min_size; | |
338 | ||
339 | if (old_tbl->size <= size) | |
340 | return 0; | |
341 | ||
b824478b HX |
342 | if (rht_dereference(old_tbl->future_tbl, ht)) |
343 | return -EEXIST; | |
344 | ||
b9ecfdaa | 345 | new_tbl = bucket_table_alloc(ht, size, GFP_KERNEL); |
97defe1e | 346 | if (new_tbl == NULL) |
7e1e7763 TG |
347 | return -ENOMEM; |
348 | ||
b824478b HX |
349 | err = rhashtable_rehash_attach(ht, old_tbl, new_tbl); |
350 | if (err) | |
351 | bucket_table_free(new_tbl); | |
352 | ||
353 | return err; | |
7e1e7763 | 354 | } |
7e1e7763 | 355 | |
97defe1e TG |
356 | static void rht_deferred_worker(struct work_struct *work) |
357 | { | |
358 | struct rhashtable *ht; | |
359 | struct bucket_table *tbl; | |
b824478b | 360 | int err = 0; |
97defe1e | 361 | |
57699a40 | 362 | ht = container_of(work, struct rhashtable, run_work); |
97defe1e | 363 | mutex_lock(&ht->mutex); |
28134a53 | 364 | |
97defe1e | 365 | tbl = rht_dereference(ht->tbl, ht); |
b824478b | 366 | tbl = rhashtable_last_table(ht, tbl); |
97defe1e | 367 | |
a5b6846f | 368 | if (rht_grow_above_75(ht, tbl)) |
97defe1e | 369 | rhashtable_expand(ht); |
b5e2c150 | 370 | else if (ht->p.automatic_shrinking && rht_shrink_below_30(ht, tbl)) |
97defe1e | 371 | rhashtable_shrink(ht); |
b824478b HX |
372 | |
373 | err = rhashtable_rehash_table(ht); | |
374 | ||
97defe1e | 375 | mutex_unlock(&ht->mutex); |
b824478b HX |
376 | |
377 | if (err) | |
378 | schedule_work(&ht->run_work); | |
97defe1e TG |
379 | } |
380 | ||
ca26893f HX |
381 | static int rhashtable_insert_rehash(struct rhashtable *ht, |
382 | struct bucket_table *tbl) | |
ccd57b1b HX |
383 | { |
384 | struct bucket_table *old_tbl; | |
385 | struct bucket_table *new_tbl; | |
ccd57b1b HX |
386 | unsigned int size; |
387 | int err; | |
388 | ||
389 | old_tbl = rht_dereference_rcu(ht->tbl, ht); | |
ccd57b1b HX |
390 | |
391 | size = tbl->size; | |
392 | ||
3cf92222 HX |
393 | err = -EBUSY; |
394 | ||
ccd57b1b HX |
395 | if (rht_grow_above_75(ht, tbl)) |
396 | size *= 2; | |
a87b9ebf TG |
397 | /* Do not schedule more than one rehash */ |
398 | else if (old_tbl != tbl) | |
3cf92222 HX |
399 | goto fail; |
400 | ||
401 | err = -ENOMEM; | |
ccd57b1b HX |
402 | |
403 | new_tbl = bucket_table_alloc(ht, size, GFP_ATOMIC); | |
3cf92222 HX |
404 | if (new_tbl == NULL) |
405 | goto fail; | |
ccd57b1b HX |
406 | |
407 | err = rhashtable_rehash_attach(ht, tbl, new_tbl); | |
408 | if (err) { | |
409 | bucket_table_free(new_tbl); | |
410 | if (err == -EEXIST) | |
411 | err = 0; | |
412 | } else | |
413 | schedule_work(&ht->run_work); | |
414 | ||
415 | return err; | |
3cf92222 HX |
416 | |
417 | fail: | |
418 | /* Do not fail the insert if someone else did a rehash. */ | |
419 | if (likely(rcu_dereference_raw(tbl->future_tbl))) | |
420 | return 0; | |
421 | ||
422 | /* Schedule async rehash to retry allocation in process context. */ | |
423 | if (err == -ENOMEM) | |
424 | schedule_work(&ht->run_work); | |
425 | ||
426 | return err; | |
ccd57b1b | 427 | } |
ccd57b1b | 428 | |
ca26893f HX |
429 | static void *rhashtable_lookup_one(struct rhashtable *ht, |
430 | struct bucket_table *tbl, unsigned int hash, | |
431 | const void *key, struct rhash_head *obj) | |
02fd97c3 | 432 | { |
ca26893f HX |
433 | struct rhashtable_compare_arg arg = { |
434 | .ht = ht, | |
435 | .key = key, | |
436 | }; | |
437 | struct rhash_head __rcu **pprev; | |
02fd97c3 | 438 | struct rhash_head *head; |
ca26893f | 439 | int elasticity; |
02fd97c3 | 440 | |
ca26893f HX |
441 | elasticity = ht->elasticity; |
442 | pprev = &tbl->buckets[hash]; | |
443 | rht_for_each(head, tbl, hash) { | |
444 | struct rhlist_head *list; | |
445 | struct rhlist_head *plist; | |
446 | ||
447 | elasticity--; | |
448 | if (!key || | |
449 | (ht->p.obj_cmpfn ? | |
450 | ht->p.obj_cmpfn(&arg, rht_obj(ht, head)) : | |
451 | rhashtable_compare(&arg, rht_obj(ht, head)))) | |
452 | continue; | |
453 | ||
454 | if (!ht->rhlist) | |
455 | return rht_obj(ht, head); | |
456 | ||
457 | list = container_of(obj, struct rhlist_head, rhead); | |
458 | plist = container_of(head, struct rhlist_head, rhead); | |
459 | ||
460 | RCU_INIT_POINTER(list->next, plist); | |
461 | head = rht_dereference_bucket(head->next, tbl, hash); | |
462 | RCU_INIT_POINTER(list->rhead.next, head); | |
463 | rcu_assign_pointer(*pprev, obj); | |
464 | ||
465 | return NULL; | |
5ca8cc5b | 466 | } |
02fd97c3 | 467 | |
ca26893f HX |
468 | if (elasticity <= 0) |
469 | return ERR_PTR(-EAGAIN); | |
470 | ||
471 | return ERR_PTR(-ENOENT); | |
472 | } | |
473 | ||
474 | static struct bucket_table *rhashtable_insert_one(struct rhashtable *ht, | |
475 | struct bucket_table *tbl, | |
476 | unsigned int hash, | |
477 | struct rhash_head *obj, | |
478 | void *data) | |
479 | { | |
480 | struct bucket_table *new_tbl; | |
481 | struct rhash_head *head; | |
482 | ||
483 | if (!IS_ERR_OR_NULL(data)) | |
484 | return ERR_PTR(-EEXIST); | |
07ee0722 | 485 | |
ca26893f HX |
486 | if (PTR_ERR(data) != -EAGAIN && PTR_ERR(data) != -ENOENT) |
487 | return ERR_CAST(data); | |
ccd57b1b | 488 | |
ca26893f HX |
489 | new_tbl = rcu_dereference(tbl->future_tbl); |
490 | if (new_tbl) | |
491 | return new_tbl; | |
492 | ||
493 | if (PTR_ERR(data) != -ENOENT) | |
494 | return ERR_CAST(data); | |
495 | ||
496 | if (unlikely(rht_grow_above_max(ht, tbl))) | |
497 | return ERR_PTR(-E2BIG); | |
498 | ||
499 | if (unlikely(rht_grow_above_100(ht, tbl))) | |
500 | return ERR_PTR(-EAGAIN); | |
02fd97c3 HX |
501 | |
502 | head = rht_dereference_bucket(tbl->buckets[hash], tbl, hash); | |
503 | ||
504 | RCU_INIT_POINTER(obj->next, head); | |
ca26893f HX |
505 | if (ht->rhlist) { |
506 | struct rhlist_head *list; | |
507 | ||
508 | list = container_of(obj, struct rhlist_head, rhead); | |
509 | RCU_INIT_POINTER(list->next, NULL); | |
510 | } | |
02fd97c3 HX |
511 | |
512 | rcu_assign_pointer(tbl->buckets[hash], obj); | |
513 | ||
514 | atomic_inc(&ht->nelems); | |
ca26893f HX |
515 | if (rht_grow_above_75(ht, tbl)) |
516 | schedule_work(&ht->run_work); | |
02fd97c3 | 517 | |
ca26893f HX |
518 | return NULL; |
519 | } | |
02fd97c3 | 520 | |
ca26893f HX |
521 | static void *rhashtable_try_insert(struct rhashtable *ht, const void *key, |
522 | struct rhash_head *obj) | |
523 | { | |
524 | struct bucket_table *new_tbl; | |
525 | struct bucket_table *tbl; | |
526 | unsigned int hash; | |
527 | spinlock_t *lock; | |
528 | void *data; | |
529 | ||
530 | tbl = rcu_dereference(ht->tbl); | |
531 | ||
532 | /* All insertions must grab the oldest table containing | |
533 | * the hashed bucket that is yet to be rehashed. | |
534 | */ | |
535 | for (;;) { | |
536 | hash = rht_head_hashfn(ht, tbl, obj, ht->p); | |
537 | lock = rht_bucket_lock(tbl, hash); | |
538 | spin_lock_bh(lock); | |
539 | ||
540 | if (tbl->rehash <= hash) | |
541 | break; | |
542 | ||
543 | spin_unlock_bh(lock); | |
544 | tbl = rcu_dereference(tbl->future_tbl); | |
545 | } | |
546 | ||
547 | data = rhashtable_lookup_one(ht, tbl, hash, key, obj); | |
548 | new_tbl = rhashtable_insert_one(ht, tbl, hash, obj, data); | |
549 | if (PTR_ERR(new_tbl) != -EEXIST) | |
550 | data = ERR_CAST(new_tbl); | |
551 | ||
552 | while (!IS_ERR_OR_NULL(new_tbl)) { | |
553 | tbl = new_tbl; | |
554 | hash = rht_head_hashfn(ht, tbl, obj, ht->p); | |
555 | spin_lock_nested(rht_bucket_lock(tbl, hash), | |
556 | SINGLE_DEPTH_NESTING); | |
557 | ||
558 | data = rhashtable_lookup_one(ht, tbl, hash, key, obj); | |
559 | new_tbl = rhashtable_insert_one(ht, tbl, hash, obj, data); | |
560 | if (PTR_ERR(new_tbl) != -EEXIST) | |
561 | data = ERR_CAST(new_tbl); | |
562 | ||
563 | spin_unlock(rht_bucket_lock(tbl, hash)); | |
564 | } | |
565 | ||
566 | spin_unlock_bh(lock); | |
567 | ||
568 | if (PTR_ERR(data) == -EAGAIN) | |
569 | data = ERR_PTR(rhashtable_insert_rehash(ht, tbl) ?: | |
570 | -EAGAIN); | |
571 | ||
572 | return data; | |
573 | } | |
574 | ||
575 | void *rhashtable_insert_slow(struct rhashtable *ht, const void *key, | |
576 | struct rhash_head *obj) | |
577 | { | |
578 | void *data; | |
579 | ||
580 | do { | |
581 | rcu_read_lock(); | |
582 | data = rhashtable_try_insert(ht, key, obj); | |
583 | rcu_read_unlock(); | |
584 | } while (PTR_ERR(data) == -EAGAIN); | |
585 | ||
586 | return data; | |
02fd97c3 HX |
587 | } |
588 | EXPORT_SYMBOL_GPL(rhashtable_insert_slow); | |
589 | ||
f2dba9c6 | 590 | /** |
246779dd | 591 | * rhashtable_walk_enter - Initialise an iterator |
f2dba9c6 HX |
592 | * @ht: Table to walk over |
593 | * @iter: Hash table Iterator | |
594 | * | |
595 | * This function prepares a hash table walk. | |
596 | * | |
597 | * Note that if you restart a walk after rhashtable_walk_stop you | |
598 | * may see the same object twice. Also, you may miss objects if | |
599 | * there are removals in between rhashtable_walk_stop and the next | |
600 | * call to rhashtable_walk_start. | |
601 | * | |
602 | * For a completely stable walk you should construct your own data | |
603 | * structure outside the hash table. | |
604 | * | |
605 | * This function may sleep so you must not call it from interrupt | |
606 | * context or with spin locks held. | |
607 | * | |
246779dd | 608 | * You must call rhashtable_walk_exit after this function returns. |
f2dba9c6 | 609 | */ |
246779dd | 610 | void rhashtable_walk_enter(struct rhashtable *ht, struct rhashtable_iter *iter) |
f2dba9c6 HX |
611 | { |
612 | iter->ht = ht; | |
613 | iter->p = NULL; | |
614 | iter->slot = 0; | |
615 | iter->skip = 0; | |
616 | ||
c6ff5268 | 617 | spin_lock(&ht->lock); |
246779dd | 618 | iter->walker.tbl = |
179ccc0a | 619 | rcu_dereference_protected(ht->tbl, lockdep_is_held(&ht->lock)); |
246779dd | 620 | list_add(&iter->walker.list, &iter->walker.tbl->walkers); |
c6ff5268 | 621 | spin_unlock(&ht->lock); |
f2dba9c6 | 622 | } |
246779dd | 623 | EXPORT_SYMBOL_GPL(rhashtable_walk_enter); |
f2dba9c6 HX |
624 | |
625 | /** | |
626 | * rhashtable_walk_exit - Free an iterator | |
627 | * @iter: Hash table Iterator | |
628 | * | |
629 | * This function frees resources allocated by rhashtable_walk_init. | |
630 | */ | |
631 | void rhashtable_walk_exit(struct rhashtable_iter *iter) | |
632 | { | |
c6ff5268 | 633 | spin_lock(&iter->ht->lock); |
246779dd HX |
634 | if (iter->walker.tbl) |
635 | list_del(&iter->walker.list); | |
c6ff5268 | 636 | spin_unlock(&iter->ht->lock); |
f2dba9c6 HX |
637 | } |
638 | EXPORT_SYMBOL_GPL(rhashtable_walk_exit); | |
639 | ||
640 | /** | |
641 | * rhashtable_walk_start - Start a hash table walk | |
642 | * @iter: Hash table iterator | |
643 | * | |
644 | * Start a hash table walk. Note that we take the RCU lock in all | |
645 | * cases including when we return an error. So you must always call | |
646 | * rhashtable_walk_stop to clean up. | |
647 | * | |
648 | * Returns zero if successful. | |
649 | * | |
650 | * Returns -EAGAIN if resize event occured. Note that the iterator | |
651 | * will rewind back to the beginning and you may use it immediately | |
652 | * by calling rhashtable_walk_next. | |
653 | */ | |
654 | int rhashtable_walk_start(struct rhashtable_iter *iter) | |
db4374f4 | 655 | __acquires(RCU) |
f2dba9c6 | 656 | { |
eddee5ba HX |
657 | struct rhashtable *ht = iter->ht; |
658 | ||
c6ff5268 | 659 | rcu_read_lock(); |
eddee5ba | 660 | |
c6ff5268 | 661 | spin_lock(&ht->lock); |
246779dd HX |
662 | if (iter->walker.tbl) |
663 | list_del(&iter->walker.list); | |
c6ff5268 | 664 | spin_unlock(&ht->lock); |
eddee5ba | 665 | |
246779dd HX |
666 | if (!iter->walker.tbl) { |
667 | iter->walker.tbl = rht_dereference_rcu(ht->tbl, ht); | |
f2dba9c6 HX |
668 | return -EAGAIN; |
669 | } | |
670 | ||
671 | return 0; | |
672 | } | |
673 | EXPORT_SYMBOL_GPL(rhashtable_walk_start); | |
674 | ||
675 | /** | |
676 | * rhashtable_walk_next - Return the next object and advance the iterator | |
677 | * @iter: Hash table iterator | |
678 | * | |
679 | * Note that you must call rhashtable_walk_stop when you are finished | |
680 | * with the walk. | |
681 | * | |
682 | * Returns the next object or NULL when the end of the table is reached. | |
683 | * | |
684 | * Returns -EAGAIN if resize event occured. Note that the iterator | |
685 | * will rewind back to the beginning and you may continue to use it. | |
686 | */ | |
687 | void *rhashtable_walk_next(struct rhashtable_iter *iter) | |
688 | { | |
246779dd | 689 | struct bucket_table *tbl = iter->walker.tbl; |
ca26893f | 690 | struct rhlist_head *list = iter->list; |
f2dba9c6 HX |
691 | struct rhashtable *ht = iter->ht; |
692 | struct rhash_head *p = iter->p; | |
ca26893f | 693 | bool rhlist = ht->rhlist; |
f2dba9c6 | 694 | |
f2dba9c6 | 695 | if (p) { |
ca26893f HX |
696 | if (!rhlist || !(list = rcu_dereference(list->next))) { |
697 | p = rcu_dereference(p->next); | |
698 | list = container_of(p, struct rhlist_head, rhead); | |
699 | } | |
f2dba9c6 HX |
700 | goto next; |
701 | } | |
702 | ||
703 | for (; iter->slot < tbl->size; iter->slot++) { | |
704 | int skip = iter->skip; | |
705 | ||
706 | rht_for_each_rcu(p, tbl, iter->slot) { | |
ca26893f HX |
707 | if (rhlist) { |
708 | list = container_of(p, struct rhlist_head, | |
709 | rhead); | |
710 | do { | |
711 | if (!skip) | |
712 | goto next; | |
713 | skip--; | |
714 | list = rcu_dereference(list->next); | |
715 | } while (list); | |
716 | ||
717 | continue; | |
718 | } | |
f2dba9c6 HX |
719 | if (!skip) |
720 | break; | |
721 | skip--; | |
722 | } | |
723 | ||
724 | next: | |
725 | if (!rht_is_a_nulls(p)) { | |
726 | iter->skip++; | |
727 | iter->p = p; | |
ca26893f HX |
728 | iter->list = list; |
729 | return rht_obj(ht, rhlist ? &list->rhead : p); | |
f2dba9c6 HX |
730 | } |
731 | ||
732 | iter->skip = 0; | |
733 | } | |
734 | ||
142b942a PS |
735 | iter->p = NULL; |
736 | ||
d88252f9 HX |
737 | /* Ensure we see any new tables. */ |
738 | smp_rmb(); | |
739 | ||
246779dd HX |
740 | iter->walker.tbl = rht_dereference_rcu(tbl->future_tbl, ht); |
741 | if (iter->walker.tbl) { | |
f2dba9c6 HX |
742 | iter->slot = 0; |
743 | iter->skip = 0; | |
f2dba9c6 HX |
744 | return ERR_PTR(-EAGAIN); |
745 | } | |
746 | ||
c936a79f | 747 | return NULL; |
f2dba9c6 HX |
748 | } |
749 | EXPORT_SYMBOL_GPL(rhashtable_walk_next); | |
750 | ||
751 | /** | |
752 | * rhashtable_walk_stop - Finish a hash table walk | |
753 | * @iter: Hash table iterator | |
754 | * | |
755 | * Finish a hash table walk. | |
756 | */ | |
757 | void rhashtable_walk_stop(struct rhashtable_iter *iter) | |
db4374f4 | 758 | __releases(RCU) |
f2dba9c6 | 759 | { |
eddee5ba | 760 | struct rhashtable *ht; |
246779dd | 761 | struct bucket_table *tbl = iter->walker.tbl; |
eddee5ba | 762 | |
eddee5ba | 763 | if (!tbl) |
963ecbd4 | 764 | goto out; |
eddee5ba HX |
765 | |
766 | ht = iter->ht; | |
767 | ||
ba7c95ea | 768 | spin_lock(&ht->lock); |
c4db8848 | 769 | if (tbl->rehash < tbl->size) |
246779dd | 770 | list_add(&iter->walker.list, &tbl->walkers); |
eddee5ba | 771 | else |
246779dd | 772 | iter->walker.tbl = NULL; |
ba7c95ea | 773 | spin_unlock(&ht->lock); |
eddee5ba | 774 | |
f2dba9c6 | 775 | iter->p = NULL; |
963ecbd4 HX |
776 | |
777 | out: | |
778 | rcu_read_unlock(); | |
f2dba9c6 HX |
779 | } |
780 | EXPORT_SYMBOL_GPL(rhashtable_walk_stop); | |
781 | ||
488fb86e | 782 | static size_t rounded_hashtable_size(const struct rhashtable_params *params) |
7e1e7763 | 783 | { |
94000176 | 784 | return max(roundup_pow_of_two(params->nelem_hint * 4 / 3), |
e2e21c1c | 785 | (unsigned long)params->min_size); |
7e1e7763 TG |
786 | } |
787 | ||
31ccde2d HX |
788 | static u32 rhashtable_jhash2(const void *key, u32 length, u32 seed) |
789 | { | |
790 | return jhash2(key, length, seed); | |
791 | } | |
792 | ||
7e1e7763 TG |
793 | /** |
794 | * rhashtable_init - initialize a new hash table | |
795 | * @ht: hash table to be initialized | |
796 | * @params: configuration parameters | |
797 | * | |
798 | * Initializes a new hash table based on the provided configuration | |
799 | * parameters. A table can be configured either with a variable or | |
800 | * fixed length key: | |
801 | * | |
802 | * Configuration Example 1: Fixed length keys | |
803 | * struct test_obj { | |
804 | * int key; | |
805 | * void * my_member; | |
806 | * struct rhash_head node; | |
807 | * }; | |
808 | * | |
809 | * struct rhashtable_params params = { | |
810 | * .head_offset = offsetof(struct test_obj, node), | |
811 | * .key_offset = offsetof(struct test_obj, key), | |
812 | * .key_len = sizeof(int), | |
87545899 | 813 | * .hashfn = jhash, |
f89bd6f8 | 814 | * .nulls_base = (1U << RHT_BASE_SHIFT), |
7e1e7763 TG |
815 | * }; |
816 | * | |
817 | * Configuration Example 2: Variable length keys | |
818 | * struct test_obj { | |
819 | * [...] | |
820 | * struct rhash_head node; | |
821 | * }; | |
822 | * | |
49f7b33e | 823 | * u32 my_hash_fn(const void *data, u32 len, u32 seed) |
7e1e7763 TG |
824 | * { |
825 | * struct test_obj *obj = data; | |
826 | * | |
827 | * return [... hash ...]; | |
828 | * } | |
829 | * | |
830 | * struct rhashtable_params params = { | |
831 | * .head_offset = offsetof(struct test_obj, node), | |
87545899 | 832 | * .hashfn = jhash, |
7e1e7763 | 833 | * .obj_hashfn = my_hash_fn, |
7e1e7763 TG |
834 | * }; |
835 | */ | |
488fb86e HX |
836 | int rhashtable_init(struct rhashtable *ht, |
837 | const struct rhashtable_params *params) | |
7e1e7763 TG |
838 | { |
839 | struct bucket_table *tbl; | |
840 | size_t size; | |
841 | ||
842 | size = HASH_DEFAULT_SIZE; | |
843 | ||
31ccde2d | 844 | if ((!params->key_len && !params->obj_hashfn) || |
02fd97c3 | 845 | (params->obj_hashfn && !params->obj_cmpfn)) |
7e1e7763 TG |
846 | return -EINVAL; |
847 | ||
f89bd6f8 TG |
848 | if (params->nulls_base && params->nulls_base < (1U << RHT_BASE_SHIFT)) |
849 | return -EINVAL; | |
850 | ||
97defe1e TG |
851 | memset(ht, 0, sizeof(*ht)); |
852 | mutex_init(&ht->mutex); | |
ba7c95ea | 853 | spin_lock_init(&ht->lock); |
97defe1e TG |
854 | memcpy(&ht->p, params, sizeof(*params)); |
855 | ||
a998f712 TG |
856 | if (params->min_size) |
857 | ht->p.min_size = roundup_pow_of_two(params->min_size); | |
858 | ||
859 | if (params->max_size) | |
860 | ht->p.max_size = rounddown_pow_of_two(params->max_size); | |
861 | ||
07ee0722 HX |
862 | if (params->insecure_max_entries) |
863 | ht->p.insecure_max_entries = | |
864 | rounddown_pow_of_two(params->insecure_max_entries); | |
865 | else | |
866 | ht->p.insecure_max_entries = ht->p.max_size * 2; | |
867 | ||
488fb86e | 868 | ht->p.min_size = max(ht->p.min_size, HASH_MIN_SIZE); |
a998f712 | 869 | |
3a324606 HX |
870 | if (params->nelem_hint) |
871 | size = rounded_hashtable_size(&ht->p); | |
872 | ||
27ed44a5 HX |
873 | /* The maximum (not average) chain length grows with the |
874 | * size of the hash table, at a rate of (log N)/(log log N). | |
875 | * The value of 16 is selected so that even if the hash | |
876 | * table grew to 2^32 you would not expect the maximum | |
877 | * chain length to exceed it unless we are under attack | |
878 | * (or extremely unlucky). | |
879 | * | |
880 | * As this limit is only to detect attacks, we don't need | |
881 | * to set it to a lower value as you'd need the chain | |
882 | * length to vastly exceed 16 to have any real effect | |
883 | * on the system. | |
884 | */ | |
ccd57b1b HX |
885 | if (!params->insecure_elasticity) |
886 | ht->elasticity = 16; | |
887 | ||
97defe1e TG |
888 | if (params->locks_mul) |
889 | ht->p.locks_mul = roundup_pow_of_two(params->locks_mul); | |
890 | else | |
891 | ht->p.locks_mul = BUCKET_LOCKS_PER_CPU; | |
892 | ||
31ccde2d HX |
893 | ht->key_len = ht->p.key_len; |
894 | if (!params->hashfn) { | |
895 | ht->p.hashfn = jhash; | |
896 | ||
897 | if (!(ht->key_len & (sizeof(u32) - 1))) { | |
898 | ht->key_len /= sizeof(u32); | |
899 | ht->p.hashfn = rhashtable_jhash2; | |
900 | } | |
901 | } | |
902 | ||
b9ecfdaa | 903 | tbl = bucket_table_alloc(ht, size, GFP_KERNEL); |
7e1e7763 TG |
904 | if (tbl == NULL) |
905 | return -ENOMEM; | |
906 | ||
545a148e | 907 | atomic_set(&ht->nelems, 0); |
a5b6846f | 908 | |
7e1e7763 TG |
909 | RCU_INIT_POINTER(ht->tbl, tbl); |
910 | ||
4c4b52d9 | 911 | INIT_WORK(&ht->run_work, rht_deferred_worker); |
97defe1e | 912 | |
7e1e7763 TG |
913 | return 0; |
914 | } | |
915 | EXPORT_SYMBOL_GPL(rhashtable_init); | |
916 | ||
ca26893f HX |
917 | /** |
918 | * rhltable_init - initialize a new hash list table | |
919 | * @hlt: hash list table to be initialized | |
920 | * @params: configuration parameters | |
921 | * | |
922 | * Initializes a new hash list table. | |
923 | * | |
924 | * See documentation for rhashtable_init. | |
925 | */ | |
926 | int rhltable_init(struct rhltable *hlt, const struct rhashtable_params *params) | |
927 | { | |
928 | int err; | |
929 | ||
930 | /* No rhlist NULLs marking for now. */ | |
931 | if (params->nulls_base) | |
932 | return -EINVAL; | |
933 | ||
934 | err = rhashtable_init(&hlt->ht, params); | |
935 | hlt->ht.rhlist = true; | |
936 | return err; | |
937 | } | |
938 | EXPORT_SYMBOL_GPL(rhltable_init); | |
939 | ||
940 | static void rhashtable_free_one(struct rhashtable *ht, struct rhash_head *obj, | |
941 | void (*free_fn)(void *ptr, void *arg), | |
942 | void *arg) | |
943 | { | |
944 | struct rhlist_head *list; | |
945 | ||
946 | if (!ht->rhlist) { | |
947 | free_fn(rht_obj(ht, obj), arg); | |
948 | return; | |
949 | } | |
950 | ||
951 | list = container_of(obj, struct rhlist_head, rhead); | |
952 | do { | |
953 | obj = &list->rhead; | |
954 | list = rht_dereference(list->next, ht); | |
955 | free_fn(rht_obj(ht, obj), arg); | |
956 | } while (list); | |
957 | } | |
958 | ||
7e1e7763 | 959 | /** |
6b6f302c | 960 | * rhashtable_free_and_destroy - free elements and destroy hash table |
7e1e7763 | 961 | * @ht: the hash table to destroy |
6b6f302c TG |
962 | * @free_fn: callback to release resources of element |
963 | * @arg: pointer passed to free_fn | |
7e1e7763 | 964 | * |
6b6f302c TG |
965 | * Stops an eventual async resize. If defined, invokes free_fn for each |
966 | * element to releasal resources. Please note that RCU protected | |
967 | * readers may still be accessing the elements. Releasing of resources | |
968 | * must occur in a compatible manner. Then frees the bucket array. | |
969 | * | |
970 | * This function will eventually sleep to wait for an async resize | |
971 | * to complete. The caller is responsible that no further write operations | |
972 | * occurs in parallel. | |
7e1e7763 | 973 | */ |
6b6f302c TG |
974 | void rhashtable_free_and_destroy(struct rhashtable *ht, |
975 | void (*free_fn)(void *ptr, void *arg), | |
976 | void *arg) | |
7e1e7763 | 977 | { |
6b6f302c TG |
978 | const struct bucket_table *tbl; |
979 | unsigned int i; | |
97defe1e | 980 | |
4c4b52d9 | 981 | cancel_work_sync(&ht->run_work); |
97defe1e | 982 | |
57699a40 | 983 | mutex_lock(&ht->mutex); |
6b6f302c TG |
984 | tbl = rht_dereference(ht->tbl, ht); |
985 | if (free_fn) { | |
986 | for (i = 0; i < tbl->size; i++) { | |
987 | struct rhash_head *pos, *next; | |
988 | ||
989 | for (pos = rht_dereference(tbl->buckets[i], ht), | |
990 | next = !rht_is_a_nulls(pos) ? | |
991 | rht_dereference(pos->next, ht) : NULL; | |
992 | !rht_is_a_nulls(pos); | |
993 | pos = next, | |
994 | next = !rht_is_a_nulls(pos) ? | |
995 | rht_dereference(pos->next, ht) : NULL) | |
ca26893f | 996 | rhashtable_free_one(ht, pos, free_fn, arg); |
6b6f302c TG |
997 | } |
998 | } | |
999 | ||
1000 | bucket_table_free(tbl); | |
97defe1e | 1001 | mutex_unlock(&ht->mutex); |
7e1e7763 | 1002 | } |
6b6f302c TG |
1003 | EXPORT_SYMBOL_GPL(rhashtable_free_and_destroy); |
1004 | ||
1005 | void rhashtable_destroy(struct rhashtable *ht) | |
1006 | { | |
1007 | return rhashtable_free_and_destroy(ht, NULL, NULL); | |
1008 | } | |
7e1e7763 | 1009 | EXPORT_SYMBOL_GPL(rhashtable_destroy); |