Line data Source code
1 : /* SPDX-License-Identifier: GPL-2.0 */
2 : /*
3 : * Resizable, Scalable, Concurrent Hash Table
4 : *
5 : * Copyright (c) 2015-2016 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 : * This program is free software; you can redistribute it and/or modify
14 : * it under the terms of the GNU General Public License version 2 as
15 : * published by the Free Software Foundation.
16 : */
17 :
18 : #ifndef _LINUX_RHASHTABLE_H
19 : #define _LINUX_RHASHTABLE_H
20 :
21 : #include <linux/err.h>
22 : #include <linux/errno.h>
23 : #include <linux/jhash.h>
24 : #include <linux/list_nulls.h>
25 : #include <linux/workqueue.h>
26 : #include <linux/rculist.h>
27 : #include <linux/bit_spinlock.h>
28 :
29 : #include <linux/rhashtable-types.h>
30 : /*
31 : * Objects in an rhashtable have an embedded struct rhash_head
32 : * which is linked into as hash chain from the hash table - or one
33 : * of two or more hash tables when the rhashtable is being resized.
34 : * The end of the chain is marked with a special nulls marks which has
35 : * the least significant bit set but otherwise stores the address of
36 : * the hash bucket. This allows us to be sure we've found the end
37 : * of the right list.
38 : * The value stored in the hash bucket has BIT(0) used as a lock bit.
39 : * This bit must be atomically set before any changes are made to
40 : * the chain. To avoid dereferencing this pointer without clearing
41 : * the bit first, we use an opaque 'struct rhash_lock_head *' for the
42 : * pointer stored in the bucket. This struct needs to be defined so
43 : * that rcu_dereference() works on it, but it has no content so a
44 : * cast is needed for it to be useful. This ensures it isn't
45 : * used by mistake with clearing the lock bit first.
46 : */
47 : struct rhash_lock_head {};
48 :
49 : /* Maximum chain length before rehash
50 : *
51 : * The maximum (not average) chain length grows with the size of the hash
52 : * table, at a rate of (log N)/(log log N).
53 : *
54 : * The value of 16 is selected so that even if the hash table grew to
55 : * 2^32 you would not expect the maximum chain length to exceed it
56 : * unless we are under attack (or extremely unlucky).
57 : *
58 : * As this limit is only to detect attacks, we don't need to set it to a
59 : * lower value as you'd need the chain length to vastly exceed 16 to have
60 : * any real effect on the system.
61 : */
62 : #define RHT_ELASTICITY 16u
63 :
64 : /**
65 : * struct bucket_table - Table of hash buckets
66 : * @size: Number of hash buckets
67 : * @nest: Number of bits of first-level nested table.
68 : * @rehash: Current bucket being rehashed
69 : * @hash_rnd: Random seed to fold into hash
70 : * @walkers: List of active walkers
71 : * @rcu: RCU structure for freeing the table
72 : * @future_tbl: Table under construction during rehashing
73 : * @ntbl: Nested table used when out of memory.
74 : * @buckets: size * hash buckets
75 : */
76 : struct bucket_table {
77 : unsigned int size;
78 : unsigned int nest;
79 : u32 hash_rnd;
80 : struct list_head walkers;
81 : struct rcu_head rcu;
82 :
83 : struct bucket_table __rcu *future_tbl;
84 :
85 : struct lockdep_map dep_map;
86 :
87 : struct rhash_lock_head __rcu *buckets[] ____cacheline_aligned_in_smp;
88 : };
89 :
90 : /*
91 : * NULLS_MARKER() expects a hash value with the low
92 : * bits mostly likely to be significant, and it discards
93 : * the msb.
94 : * We give it an address, in which the bottom bit is
95 : * always 0, and the msb might be significant.
96 : * So we shift the address down one bit to align with
97 : * expectations and avoid losing a significant bit.
98 : *
99 : * We never store the NULLS_MARKER in the hash table
100 : * itself as we need the lsb for locking.
101 : * Instead we store a NULL
102 : */
103 : #define RHT_NULLS_MARKER(ptr) \
104 : ((void *)NULLS_MARKER(((unsigned long) (ptr)) >> 1))
105 : #define INIT_RHT_NULLS_HEAD(ptr) \
106 : ((ptr) = NULL)
107 :
108 : static inline bool rht_is_a_nulls(const struct rhash_head *ptr)
109 : {
110 0 : return ((unsigned long) ptr & 1);
111 : }
112 :
113 : static inline void *rht_obj(const struct rhashtable *ht,
114 : const struct rhash_head *he)
115 : {
116 0 : return (char *)he - ht->p.head_offset;
117 : }
118 :
119 : static inline unsigned int rht_bucket_index(const struct bucket_table *tbl,
120 : unsigned int hash)
121 : {
122 0 : return hash & (tbl->size - 1);
123 : }
124 :
125 0 : static inline unsigned int rht_key_get_hash(struct rhashtable *ht,
126 : const void *key, const struct rhashtable_params params,
127 : unsigned int hash_rnd)
128 : {
129 : unsigned int hash;
130 :
131 : /* params must be equal to ht->p if it isn't constant. */
132 0 : if (!__builtin_constant_p(params.key_len))
133 0 : hash = ht->p.hashfn(key, ht->key_len, hash_rnd);
134 0 : else if (params.key_len) {
135 0 : unsigned int key_len = params.key_len;
136 :
137 0 : if (params.hashfn)
138 0 : hash = params.hashfn(key, key_len, hash_rnd);
139 0 : else if (key_len & (sizeof(u32) - 1))
140 0 : hash = jhash(key, key_len, hash_rnd);
141 : else
142 0 : hash = jhash2(key, key_len / sizeof(u32), hash_rnd);
143 : } else {
144 0 : unsigned int key_len = ht->p.key_len;
145 :
146 0 : if (params.hashfn)
147 0 : hash = params.hashfn(key, key_len, hash_rnd);
148 : else
149 0 : hash = jhash(key, key_len, hash_rnd);
150 : }
151 :
152 0 : return hash;
153 : }
154 :
155 : static inline unsigned int rht_key_hashfn(
156 : struct rhashtable *ht, const struct bucket_table *tbl,
157 : const void *key, const struct rhashtable_params params)
158 : {
159 0 : unsigned int hash = rht_key_get_hash(ht, key, params, tbl->hash_rnd);
160 :
161 0 : return rht_bucket_index(tbl, hash);
162 : }
163 :
164 0 : static inline unsigned int rht_head_hashfn(
165 : struct rhashtable *ht, const struct bucket_table *tbl,
166 : const struct rhash_head *he, const struct rhashtable_params params)
167 : {
168 0 : const char *ptr = rht_obj(ht, he);
169 :
170 0 : return likely(params.obj_hashfn) ?
171 0 : rht_bucket_index(tbl, params.obj_hashfn(ptr, params.key_len ?:
172 0 : ht->p.key_len,
173 0 : tbl->hash_rnd)) :
174 0 : rht_key_hashfn(ht, tbl, ptr + params.key_offset, params);
175 : }
176 :
177 : /**
178 : * rht_grow_above_75 - returns true if nelems > 0.75 * table-size
179 : * @ht: hash table
180 : * @tbl: current table
181 : */
182 : static inline bool rht_grow_above_75(const struct rhashtable *ht,
183 : const struct bucket_table *tbl)
184 : {
185 : /* Expand table when exceeding 75% load */
186 0 : return atomic_read(&ht->nelems) > (tbl->size / 4 * 3) &&
187 0 : (!ht->p.max_size || tbl->size < ht->p.max_size);
188 : }
189 :
190 : /**
191 : * rht_shrink_below_30 - returns true if nelems < 0.3 * table-size
192 : * @ht: hash table
193 : * @tbl: current table
194 : */
195 : static inline bool rht_shrink_below_30(const struct rhashtable *ht,
196 : const struct bucket_table *tbl)
197 : {
198 : /* Shrink table beneath 30% load */
199 0 : return atomic_read(&ht->nelems) < (tbl->size * 3 / 10) &&
200 0 : tbl->size > ht->p.min_size;
201 : }
202 :
203 : /**
204 : * rht_grow_above_100 - returns true if nelems > table-size
205 : * @ht: hash table
206 : * @tbl: current table
207 : */
208 : static inline bool rht_grow_above_100(const struct rhashtable *ht,
209 : const struct bucket_table *tbl)
210 : {
211 0 : return atomic_read(&ht->nelems) > tbl->size &&
212 0 : (!ht->p.max_size || tbl->size < ht->p.max_size);
213 : }
214 :
215 : /**
216 : * rht_grow_above_max - returns true if table is above maximum
217 : * @ht: hash table
218 : * @tbl: current table
219 : */
220 : static inline bool rht_grow_above_max(const struct rhashtable *ht,
221 : const struct bucket_table *tbl)
222 : {
223 0 : return atomic_read(&ht->nelems) >= ht->max_elems;
224 : }
225 :
226 : #ifdef CONFIG_PROVE_LOCKING
227 : int lockdep_rht_mutex_is_held(struct rhashtable *ht);
228 : int lockdep_rht_bucket_is_held(const struct bucket_table *tbl, u32 hash);
229 : #else
230 : static inline int lockdep_rht_mutex_is_held(struct rhashtable *ht)
231 : {
232 : return 1;
233 : }
234 :
235 : static inline int lockdep_rht_bucket_is_held(const struct bucket_table *tbl,
236 : u32 hash)
237 : {
238 : return 1;
239 : }
240 : #endif /* CONFIG_PROVE_LOCKING */
241 :
242 : void *rhashtable_insert_slow(struct rhashtable *ht, const void *key,
243 : struct rhash_head *obj);
244 :
245 : void rhashtable_walk_enter(struct rhashtable *ht,
246 : struct rhashtable_iter *iter);
247 : void rhashtable_walk_exit(struct rhashtable_iter *iter);
248 : int rhashtable_walk_start_check(struct rhashtable_iter *iter) __acquires(RCU);
249 :
250 : static inline void rhashtable_walk_start(struct rhashtable_iter *iter)
251 : {
252 : (void)rhashtable_walk_start_check(iter);
253 : }
254 :
255 : void *rhashtable_walk_next(struct rhashtable_iter *iter);
256 : void *rhashtable_walk_peek(struct rhashtable_iter *iter);
257 : void rhashtable_walk_stop(struct rhashtable_iter *iter) __releases(RCU);
258 :
259 : void rhashtable_free_and_destroy(struct rhashtable *ht,
260 : void (*free_fn)(void *ptr, void *arg),
261 : void *arg);
262 : void rhashtable_destroy(struct rhashtable *ht);
263 :
264 : struct rhash_lock_head __rcu **rht_bucket_nested(
265 : const struct bucket_table *tbl, unsigned int hash);
266 : struct rhash_lock_head __rcu **__rht_bucket_nested(
267 : const struct bucket_table *tbl, unsigned int hash);
268 : struct rhash_lock_head __rcu **rht_bucket_nested_insert(
269 : struct rhashtable *ht, struct bucket_table *tbl, unsigned int hash);
270 :
271 : #define rht_dereference(p, ht) \
272 : rcu_dereference_protected(p, lockdep_rht_mutex_is_held(ht))
273 :
274 : #define rht_dereference_rcu(p, ht) \
275 : rcu_dereference_check(p, lockdep_rht_mutex_is_held(ht))
276 :
277 : #define rht_dereference_bucket(p, tbl, hash) \
278 : rcu_dereference_protected(p, lockdep_rht_bucket_is_held(tbl, hash))
279 :
280 : #define rht_dereference_bucket_rcu(p, tbl, hash) \
281 : rcu_dereference_check(p, lockdep_rht_bucket_is_held(tbl, hash))
282 :
283 : #define rht_entry(tpos, pos, member) \
284 : ({ tpos = container_of(pos, typeof(*tpos), member); 1; })
285 :
286 0 : static inline struct rhash_lock_head __rcu *const *rht_bucket(
287 : const struct bucket_table *tbl, unsigned int hash)
288 : {
289 0 : return unlikely(tbl->nest) ? rht_bucket_nested(tbl, hash) :
290 : &tbl->buckets[hash];
291 : }
292 :
293 : static inline struct rhash_lock_head __rcu **rht_bucket_var(
294 : struct bucket_table *tbl, unsigned int hash)
295 : {
296 0 : return unlikely(tbl->nest) ? __rht_bucket_nested(tbl, hash) :
297 : &tbl->buckets[hash];
298 : }
299 :
300 : static inline struct rhash_lock_head __rcu **rht_bucket_insert(
301 : struct rhashtable *ht, struct bucket_table *tbl, unsigned int hash)
302 : {
303 0 : return unlikely(tbl->nest) ? rht_bucket_nested_insert(ht, tbl, hash) :
304 : &tbl->buckets[hash];
305 : }
306 :
307 : /*
308 : * We lock a bucket by setting BIT(0) in the pointer - this is always
309 : * zero in real pointers. The NULLS mark is never stored in the bucket,
310 : * rather we store NULL if the bucket is empty.
311 : * bit_spin_locks do not handle contention well, but the whole point
312 : * of the hashtable design is to achieve minimum per-bucket contention.
313 : * A nested hash table might not have a bucket pointer. In that case
314 : * we cannot get a lock. For remove and replace the bucket cannot be
315 : * interesting and doesn't need locking.
316 : * For insert we allocate the bucket if this is the last bucket_table,
317 : * and then take the lock.
318 : * Sometimes we unlock a bucket by writing a new pointer there. In that
319 : * case we don't need to unlock, but we do need to reset state such as
320 : * local_bh. For that we have rht_assign_unlock(). As rcu_assign_pointer()
321 : * provides the same release semantics that bit_spin_unlock() provides,
322 : * this is safe.
323 : * When we write to a bucket without unlocking, we use rht_assign_locked().
324 : */
325 :
326 : static inline unsigned long rht_lock(struct bucket_table *tbl,
327 : struct rhash_lock_head __rcu **bkt)
328 : {
329 : unsigned long flags;
330 :
331 0 : local_irq_save(flags);
332 0 : bit_spin_lock(0, (unsigned long *)bkt);
333 : lock_map_acquire(&tbl->dep_map);
334 : return flags;
335 : }
336 :
337 : static inline unsigned long rht_lock_nested(struct bucket_table *tbl,
338 : struct rhash_lock_head __rcu **bucket,
339 : unsigned int subclass)
340 : {
341 : unsigned long flags;
342 :
343 0 : local_irq_save(flags);
344 0 : bit_spin_lock(0, (unsigned long *)bucket);
345 : lock_acquire_exclusive(&tbl->dep_map, subclass, 0, NULL, _THIS_IP_);
346 : return flags;
347 : }
348 :
349 : static inline void rht_unlock(struct bucket_table *tbl,
350 : struct rhash_lock_head __rcu **bkt,
351 : unsigned long flags)
352 : {
353 : lock_map_release(&tbl->dep_map);
354 0 : bit_spin_unlock(0, (unsigned long *)bkt);
355 0 : local_irq_restore(flags);
356 : }
357 :
358 : static inline struct rhash_head *__rht_ptr(
359 : struct rhash_lock_head *p, struct rhash_lock_head __rcu *const *bkt)
360 : {
361 0 : return (struct rhash_head *)
362 0 : ((unsigned long)p & ~BIT(0) ?:
363 0 : (unsigned long)RHT_NULLS_MARKER(bkt));
364 : }
365 :
366 : /*
367 : * Where 'bkt' is a bucket and might be locked:
368 : * rht_ptr_rcu() dereferences that pointer and clears the lock bit.
369 : * rht_ptr() dereferences in a context where the bucket is locked.
370 : * rht_ptr_exclusive() dereferences in a context where exclusive
371 : * access is guaranteed, such as when destroying the table.
372 : */
373 : static inline struct rhash_head *rht_ptr_rcu(
374 : struct rhash_lock_head __rcu *const *bkt)
375 : {
376 0 : return __rht_ptr(rcu_dereference(*bkt), bkt);
377 : }
378 :
379 : static inline struct rhash_head *rht_ptr(
380 : struct rhash_lock_head __rcu *const *bkt,
381 : struct bucket_table *tbl,
382 : unsigned int hash)
383 : {
384 0 : return __rht_ptr(rht_dereference_bucket(*bkt, tbl, hash), bkt);
385 : }
386 :
387 : static inline struct rhash_head *rht_ptr_exclusive(
388 : struct rhash_lock_head __rcu *const *bkt)
389 : {
390 0 : return __rht_ptr(rcu_dereference_protected(*bkt, 1), bkt);
391 : }
392 :
393 : static inline void rht_assign_locked(struct rhash_lock_head __rcu **bkt,
394 : struct rhash_head *obj)
395 : {
396 0 : if (rht_is_a_nulls(obj))
397 0 : obj = NULL;
398 0 : rcu_assign_pointer(*bkt, (void *)((unsigned long)obj | BIT(0)));
399 : }
400 :
401 : static inline void rht_assign_unlock(struct bucket_table *tbl,
402 : struct rhash_lock_head __rcu **bkt,
403 : struct rhash_head *obj,
404 : unsigned long flags)
405 : {
406 0 : if (rht_is_a_nulls(obj))
407 0 : obj = NULL;
408 : lock_map_release(&tbl->dep_map);
409 0 : rcu_assign_pointer(*bkt, (void *)obj);
410 0 : preempt_enable();
411 : __release(bitlock);
412 0 : local_irq_restore(flags);
413 : }
414 :
415 : /**
416 : * rht_for_each_from - iterate over hash chain from given head
417 : * @pos: the &struct rhash_head to use as a loop cursor.
418 : * @head: the &struct rhash_head to start from
419 : * @tbl: the &struct bucket_table
420 : * @hash: the hash value / bucket index
421 : */
422 : #define rht_for_each_from(pos, head, tbl, hash) \
423 : for (pos = head; \
424 : !rht_is_a_nulls(pos); \
425 : pos = rht_dereference_bucket((pos)->next, tbl, hash))
426 :
427 : /**
428 : * rht_for_each - iterate over hash chain
429 : * @pos: the &struct rhash_head to use as a loop cursor.
430 : * @tbl: the &struct bucket_table
431 : * @hash: the hash value / bucket index
432 : */
433 : #define rht_for_each(pos, tbl, hash) \
434 : rht_for_each_from(pos, rht_ptr(rht_bucket(tbl, hash), tbl, hash), \
435 : tbl, hash)
436 :
437 : /**
438 : * rht_for_each_entry_from - iterate over hash chain from given head
439 : * @tpos: the type * to use as a loop cursor.
440 : * @pos: the &struct rhash_head to use as a loop cursor.
441 : * @head: the &struct rhash_head to start from
442 : * @tbl: the &struct bucket_table
443 : * @hash: the hash value / bucket index
444 : * @member: name of the &struct rhash_head within the hashable struct.
445 : */
446 : #define rht_for_each_entry_from(tpos, pos, head, tbl, hash, member) \
447 : for (pos = head; \
448 : (!rht_is_a_nulls(pos)) && rht_entry(tpos, pos, member); \
449 : pos = rht_dereference_bucket((pos)->next, tbl, hash))
450 :
451 : /**
452 : * rht_for_each_entry - iterate over hash chain of given type
453 : * @tpos: the type * to use as a loop cursor.
454 : * @pos: the &struct rhash_head to use as a loop cursor.
455 : * @tbl: the &struct bucket_table
456 : * @hash: the hash value / bucket index
457 : * @member: name of the &struct rhash_head within the hashable struct.
458 : */
459 : #define rht_for_each_entry(tpos, pos, tbl, hash, member) \
460 : rht_for_each_entry_from(tpos, pos, \
461 : rht_ptr(rht_bucket(tbl, hash), tbl, hash), \
462 : tbl, hash, member)
463 :
464 : /**
465 : * rht_for_each_entry_safe - safely iterate over hash chain of given type
466 : * @tpos: the type * to use as a loop cursor.
467 : * @pos: the &struct rhash_head to use as a loop cursor.
468 : * @next: the &struct rhash_head to use as next in loop cursor.
469 : * @tbl: the &struct bucket_table
470 : * @hash: the hash value / bucket index
471 : * @member: name of the &struct rhash_head within the hashable struct.
472 : *
473 : * This hash chain list-traversal primitive allows for the looped code to
474 : * remove the loop cursor from the list.
475 : */
476 : #define rht_for_each_entry_safe(tpos, pos, next, tbl, hash, member) \
477 : for (pos = rht_ptr(rht_bucket(tbl, hash), tbl, hash), \
478 : next = !rht_is_a_nulls(pos) ? \
479 : rht_dereference_bucket(pos->next, tbl, hash) : NULL; \
480 : (!rht_is_a_nulls(pos)) && rht_entry(tpos, pos, member); \
481 : pos = next, \
482 : next = !rht_is_a_nulls(pos) ? \
483 : rht_dereference_bucket(pos->next, tbl, hash) : NULL)
484 :
485 : /**
486 : * rht_for_each_rcu_from - iterate over rcu hash chain from given head
487 : * @pos: the &struct rhash_head to use as a loop cursor.
488 : * @head: the &struct rhash_head to start from
489 : * @tbl: the &struct bucket_table
490 : * @hash: the hash value / bucket index
491 : *
492 : * This hash chain list-traversal primitive may safely run concurrently with
493 : * the _rcu mutation primitives such as rhashtable_insert() as long as the
494 : * traversal is guarded by rcu_read_lock().
495 : */
496 : #define rht_for_each_rcu_from(pos, head, tbl, hash) \
497 : for (({barrier(); }), \
498 : pos = head; \
499 : !rht_is_a_nulls(pos); \
500 : pos = rcu_dereference_raw(pos->next))
501 :
502 : /**
503 : * rht_for_each_rcu - iterate over rcu hash chain
504 : * @pos: the &struct rhash_head to use as a loop cursor.
505 : * @tbl: the &struct bucket_table
506 : * @hash: the hash value / bucket index
507 : *
508 : * This hash chain list-traversal primitive may safely run concurrently with
509 : * the _rcu mutation primitives such as rhashtable_insert() as long as the
510 : * traversal is guarded by rcu_read_lock().
511 : */
512 : #define rht_for_each_rcu(pos, tbl, hash) \
513 : for (({barrier(); }), \
514 : pos = rht_ptr_rcu(rht_bucket(tbl, hash)); \
515 : !rht_is_a_nulls(pos); \
516 : pos = rcu_dereference_raw(pos->next))
517 :
518 : /**
519 : * rht_for_each_entry_rcu_from - iterated over rcu hash chain from given head
520 : * @tpos: the type * to use as a loop cursor.
521 : * @pos: the &struct rhash_head to use as a loop cursor.
522 : * @head: the &struct rhash_head to start from
523 : * @tbl: the &struct bucket_table
524 : * @hash: the hash value / bucket index
525 : * @member: name of the &struct rhash_head within the hashable struct.
526 : *
527 : * This hash chain list-traversal primitive may safely run concurrently with
528 : * the _rcu mutation primitives such as rhashtable_insert() as long as the
529 : * traversal is guarded by rcu_read_lock().
530 : */
531 : #define rht_for_each_entry_rcu_from(tpos, pos, head, tbl, hash, member) \
532 : for (({barrier(); }), \
533 : pos = head; \
534 : (!rht_is_a_nulls(pos)) && rht_entry(tpos, pos, member); \
535 : pos = rht_dereference_bucket_rcu(pos->next, tbl, hash))
536 :
537 : /**
538 : * rht_for_each_entry_rcu - iterate over rcu hash chain of given type
539 : * @tpos: the type * to use as a loop cursor.
540 : * @pos: the &struct rhash_head to use as a loop cursor.
541 : * @tbl: the &struct bucket_table
542 : * @hash: the hash value / bucket index
543 : * @member: name of the &struct rhash_head within the hashable struct.
544 : *
545 : * This hash chain list-traversal primitive may safely run concurrently with
546 : * the _rcu mutation primitives such as rhashtable_insert() as long as the
547 : * traversal is guarded by rcu_read_lock().
548 : */
549 : #define rht_for_each_entry_rcu(tpos, pos, tbl, hash, member) \
550 : rht_for_each_entry_rcu_from(tpos, pos, \
551 : rht_ptr_rcu(rht_bucket(tbl, hash)), \
552 : tbl, hash, member)
553 :
554 : /**
555 : * rhl_for_each_rcu - iterate over rcu hash table list
556 : * @pos: the &struct rlist_head to use as a loop cursor.
557 : * @list: the head of the list
558 : *
559 : * This hash chain list-traversal primitive should be used on the
560 : * list returned by rhltable_lookup.
561 : */
562 : #define rhl_for_each_rcu(pos, list) \
563 : for (pos = list; pos; pos = rcu_dereference_raw(pos->next))
564 :
565 : /**
566 : * rhl_for_each_entry_rcu - iterate over rcu hash table list of given type
567 : * @tpos: the type * to use as a loop cursor.
568 : * @pos: the &struct rlist_head to use as a loop cursor.
569 : * @list: the head of the list
570 : * @member: name of the &struct rlist_head within the hashable struct.
571 : *
572 : * This hash chain list-traversal primitive should be used on the
573 : * list returned by rhltable_lookup.
574 : */
575 : #define rhl_for_each_entry_rcu(tpos, pos, list, member) \
576 : for (pos = list; pos && rht_entry(tpos, pos, member); \
577 : pos = rcu_dereference_raw(pos->next))
578 :
579 : static inline int rhashtable_compare(struct rhashtable_compare_arg *arg,
580 : const void *obj)
581 : {
582 0 : struct rhashtable *ht = arg->ht;
583 0 : const char *ptr = obj;
584 :
585 0 : return memcmp(ptr + ht->p.key_offset, arg->key, ht->p.key_len);
586 : }
587 :
588 : /* Internal function, do not use. */
589 : static inline struct rhash_head *__rhashtable_lookup(
590 : struct rhashtable *ht, const void *key,
591 : const struct rhashtable_params params)
592 : {
593 : struct rhashtable_compare_arg arg = {
594 : .ht = ht,
595 : .key = key,
596 : };
597 : struct rhash_lock_head __rcu *const *bkt;
598 : struct bucket_table *tbl;
599 : struct rhash_head *he;
600 : unsigned int hash;
601 :
602 : tbl = rht_dereference_rcu(ht->tbl, ht);
603 : restart:
604 : hash = rht_key_hashfn(ht, tbl, key, params);
605 : bkt = rht_bucket(tbl, hash);
606 : do {
607 : rht_for_each_rcu_from(he, rht_ptr_rcu(bkt), tbl, hash) {
608 : if (params.obj_cmpfn ?
609 : params.obj_cmpfn(&arg, rht_obj(ht, he)) :
610 : rhashtable_compare(&arg, rht_obj(ht, he)))
611 : continue;
612 : return he;
613 : }
614 : /* An object might have been moved to a different hash chain,
615 : * while we walk along it - better check and retry.
616 : */
617 : } while (he != RHT_NULLS_MARKER(bkt));
618 :
619 : /* Ensure we see any new tables. */
620 : smp_rmb();
621 :
622 : tbl = rht_dereference_rcu(tbl->future_tbl, ht);
623 : if (unlikely(tbl))
624 : goto restart;
625 :
626 : return NULL;
627 : }
628 :
629 : /**
630 : * rhashtable_lookup - search hash table
631 : * @ht: hash table
632 : * @key: the pointer to the key
633 : * @params: hash table parameters
634 : *
635 : * Computes the hash value for the key and traverses the bucket chain looking
636 : * for a entry with an identical key. The first matching entry is returned.
637 : *
638 : * This must only be called under the RCU read lock.
639 : *
640 : * Returns the first entry on which the compare function returned true.
641 : */
642 : static inline void *rhashtable_lookup(
643 : struct rhashtable *ht, const void *key,
644 : const struct rhashtable_params params)
645 : {
646 : struct rhash_head *he = __rhashtable_lookup(ht, key, params);
647 :
648 : return he ? rht_obj(ht, he) : NULL;
649 : }
650 :
651 : /**
652 : * rhashtable_lookup_fast - search hash table, without RCU read lock
653 : * @ht: hash table
654 : * @key: the pointer to the key
655 : * @params: hash table parameters
656 : *
657 : * Computes the hash value for the key and traverses the bucket chain looking
658 : * for a entry with an identical key. The first matching entry is returned.
659 : *
660 : * Only use this function when you have other mechanisms guaranteeing
661 : * that the object won't go away after the RCU read lock is released.
662 : *
663 : * Returns the first entry on which the compare function returned true.
664 : */
665 : static inline void *rhashtable_lookup_fast(
666 : struct rhashtable *ht, const void *key,
667 : const struct rhashtable_params params)
668 : {
669 : void *obj;
670 :
671 : rcu_read_lock();
672 : obj = rhashtable_lookup(ht, key, params);
673 : rcu_read_unlock();
674 :
675 : return obj;
676 : }
677 :
678 : /**
679 : * rhltable_lookup - search hash list table
680 : * @hlt: hash table
681 : * @key: the pointer to the key
682 : * @params: hash table parameters
683 : *
684 : * Computes the hash value for the key and traverses the bucket chain looking
685 : * for a entry with an identical key. All matching entries are returned
686 : * in a list.
687 : *
688 : * This must only be called under the RCU read lock.
689 : *
690 : * Returns the list of entries that match the given key.
691 : */
692 : static inline struct rhlist_head *rhltable_lookup(
693 : struct rhltable *hlt, const void *key,
694 : const struct rhashtable_params params)
695 : {
696 : struct rhash_head *he = __rhashtable_lookup(&hlt->ht, key, params);
697 :
698 : return he ? container_of(he, struct rhlist_head, rhead) : NULL;
699 : }
700 :
701 : /* Internal function, please use rhashtable_insert_fast() instead. This
702 : * function returns the existing element already in hashes in there is a clash,
703 : * otherwise it returns an error via ERR_PTR().
704 : */
705 : static inline void *__rhashtable_insert_fast(
706 : struct rhashtable *ht, const void *key, struct rhash_head *obj,
707 : const struct rhashtable_params params, bool rhlist)
708 : {
709 : struct rhashtable_compare_arg arg = {
710 : .ht = ht,
711 : .key = key,
712 : };
713 : struct rhash_lock_head __rcu **bkt;
714 : struct rhash_head __rcu **pprev;
715 : struct bucket_table *tbl;
716 : struct rhash_head *head;
717 : unsigned long flags;
718 : unsigned int hash;
719 : int elasticity;
720 : void *data;
721 :
722 : rcu_read_lock();
723 :
724 : tbl = rht_dereference_rcu(ht->tbl, ht);
725 : hash = rht_head_hashfn(ht, tbl, obj, params);
726 : elasticity = RHT_ELASTICITY;
727 : bkt = rht_bucket_insert(ht, tbl, hash);
728 : data = ERR_PTR(-ENOMEM);
729 : if (!bkt)
730 : goto out;
731 : pprev = NULL;
732 : flags = rht_lock(tbl, bkt);
733 :
734 : if (unlikely(rcu_access_pointer(tbl->future_tbl))) {
735 : slow_path:
736 : rht_unlock(tbl, bkt, flags);
737 : rcu_read_unlock();
738 : return rhashtable_insert_slow(ht, key, obj);
739 : }
740 :
741 : rht_for_each_from(head, rht_ptr(bkt, tbl, hash), tbl, hash) {
742 : struct rhlist_head *plist;
743 : struct rhlist_head *list;
744 :
745 : elasticity--;
746 : if (!key ||
747 : (params.obj_cmpfn ?
748 : params.obj_cmpfn(&arg, rht_obj(ht, head)) :
749 : rhashtable_compare(&arg, rht_obj(ht, head)))) {
750 : pprev = &head->next;
751 : continue;
752 : }
753 :
754 : data = rht_obj(ht, head);
755 :
756 : if (!rhlist)
757 : goto out_unlock;
758 :
759 :
760 : list = container_of(obj, struct rhlist_head, rhead);
761 : plist = container_of(head, struct rhlist_head, rhead);
762 :
763 : RCU_INIT_POINTER(list->next, plist);
764 : head = rht_dereference_bucket(head->next, tbl, hash);
765 : RCU_INIT_POINTER(list->rhead.next, head);
766 : if (pprev) {
767 : rcu_assign_pointer(*pprev, obj);
768 : rht_unlock(tbl, bkt, flags);
769 : } else
770 : rht_assign_unlock(tbl, bkt, obj, flags);
771 : data = NULL;
772 : goto out;
773 : }
774 :
775 : if (elasticity <= 0)
776 : goto slow_path;
777 :
778 : data = ERR_PTR(-E2BIG);
779 : if (unlikely(rht_grow_above_max(ht, tbl)))
780 : goto out_unlock;
781 :
782 : if (unlikely(rht_grow_above_100(ht, tbl)))
783 : goto slow_path;
784 :
785 : /* Inserting at head of list makes unlocking free. */
786 : head = rht_ptr(bkt, tbl, hash);
787 :
788 : RCU_INIT_POINTER(obj->next, head);
789 : if (rhlist) {
790 : struct rhlist_head *list;
791 :
792 : list = container_of(obj, struct rhlist_head, rhead);
793 : RCU_INIT_POINTER(list->next, NULL);
794 : }
795 :
796 : atomic_inc(&ht->nelems);
797 : rht_assign_unlock(tbl, bkt, obj, flags);
798 :
799 : if (rht_grow_above_75(ht, tbl))
800 : schedule_work(&ht->run_work);
801 :
802 : data = NULL;
803 : out:
804 : rcu_read_unlock();
805 :
806 : return data;
807 :
808 : out_unlock:
809 : rht_unlock(tbl, bkt, flags);
810 : goto out;
811 : }
812 :
813 : /**
814 : * rhashtable_insert_fast - insert object into hash table
815 : * @ht: hash table
816 : * @obj: pointer to hash head inside object
817 : * @params: hash table parameters
818 : *
819 : * Will take the per bucket bitlock to protect against mutual mutations
820 : * on the same bucket. Multiple insertions may occur in parallel unless
821 : * they map to the same bucket.
822 : *
823 : * It is safe to call this function from atomic context.
824 : *
825 : * Will trigger an automatic deferred table resizing if residency in the
826 : * table grows beyond 70%.
827 : */
828 : static inline int rhashtable_insert_fast(
829 : struct rhashtable *ht, struct rhash_head *obj,
830 : const struct rhashtable_params params)
831 : {
832 : void *ret;
833 :
834 : ret = __rhashtable_insert_fast(ht, NULL, obj, params, false);
835 : if (IS_ERR(ret))
836 : return PTR_ERR(ret);
837 :
838 : return ret == NULL ? 0 : -EEXIST;
839 : }
840 :
841 : /**
842 : * rhltable_insert_key - insert object into hash list table
843 : * @hlt: hash list table
844 : * @key: the pointer to the key
845 : * @list: pointer to hash list head inside object
846 : * @params: hash table parameters
847 : *
848 : * Will take the per bucket bitlock to protect against mutual mutations
849 : * on the same bucket. Multiple insertions may occur in parallel unless
850 : * they map to the same bucket.
851 : *
852 : * It is safe to call this function from atomic context.
853 : *
854 : * Will trigger an automatic deferred table resizing if residency in the
855 : * table grows beyond 70%.
856 : */
857 : static inline int rhltable_insert_key(
858 : struct rhltable *hlt, const void *key, struct rhlist_head *list,
859 : const struct rhashtable_params params)
860 : {
861 : return PTR_ERR(__rhashtable_insert_fast(&hlt->ht, key, &list->rhead,
862 : params, true));
863 : }
864 :
865 : /**
866 : * rhltable_insert - insert object into hash list table
867 : * @hlt: hash list table
868 : * @list: pointer to hash list head inside object
869 : * @params: hash table parameters
870 : *
871 : * Will take the per bucket bitlock to protect against mutual mutations
872 : * on the same bucket. Multiple insertions may occur in parallel unless
873 : * they map to the same bucket.
874 : *
875 : * It is safe to call this function from atomic context.
876 : *
877 : * Will trigger an automatic deferred table resizing if residency in the
878 : * table grows beyond 70%.
879 : */
880 : static inline int rhltable_insert(
881 : struct rhltable *hlt, struct rhlist_head *list,
882 : const struct rhashtable_params params)
883 : {
884 : const char *key = rht_obj(&hlt->ht, &list->rhead);
885 :
886 : key += params.key_offset;
887 :
888 : return rhltable_insert_key(hlt, key, list, params);
889 : }
890 :
891 : /**
892 : * rhashtable_lookup_insert_fast - lookup and insert object into hash table
893 : * @ht: hash table
894 : * @obj: pointer to hash head inside object
895 : * @params: hash table parameters
896 : *
897 : * This lookup function may only be used for fixed key hash table (key_len
898 : * parameter set). It will BUG() if used inappropriately.
899 : *
900 : * It is safe to call this function from atomic context.
901 : *
902 : * Will trigger an automatic deferred table resizing if residency in the
903 : * table grows beyond 70%.
904 : */
905 : static inline int rhashtable_lookup_insert_fast(
906 : struct rhashtable *ht, struct rhash_head *obj,
907 : const struct rhashtable_params params)
908 : {
909 : const char *key = rht_obj(ht, obj);
910 : void *ret;
911 :
912 : BUG_ON(ht->p.obj_hashfn);
913 :
914 : ret = __rhashtable_insert_fast(ht, key + ht->p.key_offset, obj, params,
915 : false);
916 : if (IS_ERR(ret))
917 : return PTR_ERR(ret);
918 :
919 : return ret == NULL ? 0 : -EEXIST;
920 : }
921 :
922 : /**
923 : * rhashtable_lookup_get_insert_fast - lookup and insert object into hash table
924 : * @ht: hash table
925 : * @obj: pointer to hash head inside object
926 : * @params: hash table parameters
927 : *
928 : * Just like rhashtable_lookup_insert_fast(), but this function returns the
929 : * object if it exists, NULL if it did not and the insertion was successful,
930 : * and an ERR_PTR otherwise.
931 : */
932 : static inline void *rhashtable_lookup_get_insert_fast(
933 : struct rhashtable *ht, struct rhash_head *obj,
934 : const struct rhashtable_params params)
935 : {
936 : const char *key = rht_obj(ht, obj);
937 :
938 : BUG_ON(ht->p.obj_hashfn);
939 :
940 : return __rhashtable_insert_fast(ht, key + ht->p.key_offset, obj, params,
941 : false);
942 : }
943 :
944 : /**
945 : * rhashtable_lookup_insert_key - search and insert object to hash table
946 : * with explicit key
947 : * @ht: hash table
948 : * @key: key
949 : * @obj: pointer to hash head inside object
950 : * @params: hash table parameters
951 : *
952 : * Lookups may occur in parallel with hashtable mutations and resizing.
953 : *
954 : * Will trigger an automatic deferred table resizing if residency in the
955 : * table grows beyond 70%.
956 : *
957 : * Returns zero on success.
958 : */
959 : static inline int rhashtable_lookup_insert_key(
960 : struct rhashtable *ht, const void *key, struct rhash_head *obj,
961 : const struct rhashtable_params params)
962 : {
963 : void *ret;
964 :
965 : BUG_ON(!ht->p.obj_hashfn || !key);
966 :
967 : ret = __rhashtable_insert_fast(ht, key, obj, params, false);
968 : if (IS_ERR(ret))
969 : return PTR_ERR(ret);
970 :
971 : return ret == NULL ? 0 : -EEXIST;
972 : }
973 :
974 : /**
975 : * rhashtable_lookup_get_insert_key - lookup and insert object into hash table
976 : * @ht: hash table
977 : * @key: key
978 : * @obj: pointer to hash head inside object
979 : * @params: hash table parameters
980 : *
981 : * Just like rhashtable_lookup_insert_key(), but this function returns the
982 : * object if it exists, NULL if it does not and the insertion was successful,
983 : * and an ERR_PTR otherwise.
984 : */
985 : static inline void *rhashtable_lookup_get_insert_key(
986 : struct rhashtable *ht, const void *key, struct rhash_head *obj,
987 : const struct rhashtable_params params)
988 : {
989 : BUG_ON(!ht->p.obj_hashfn || !key);
990 :
991 : return __rhashtable_insert_fast(ht, key, obj, params, false);
992 : }
993 :
994 : /* Internal function, please use rhashtable_remove_fast() instead */
995 : static inline int __rhashtable_remove_fast_one(
996 : struct rhashtable *ht, struct bucket_table *tbl,
997 : struct rhash_head *obj, const struct rhashtable_params params,
998 : bool rhlist)
999 : {
1000 : struct rhash_lock_head __rcu **bkt;
1001 : struct rhash_head __rcu **pprev;
1002 : struct rhash_head *he;
1003 : unsigned long flags;
1004 : unsigned int hash;
1005 : int err = -ENOENT;
1006 :
1007 : hash = rht_head_hashfn(ht, tbl, obj, params);
1008 : bkt = rht_bucket_var(tbl, hash);
1009 : if (!bkt)
1010 : return -ENOENT;
1011 : pprev = NULL;
1012 : flags = rht_lock(tbl, bkt);
1013 :
1014 : rht_for_each_from(he, rht_ptr(bkt, tbl, hash), tbl, hash) {
1015 : struct rhlist_head *list;
1016 :
1017 : list = container_of(he, struct rhlist_head, rhead);
1018 :
1019 : if (he != obj) {
1020 : struct rhlist_head __rcu **lpprev;
1021 :
1022 : pprev = &he->next;
1023 :
1024 : if (!rhlist)
1025 : continue;
1026 :
1027 : do {
1028 : lpprev = &list->next;
1029 : list = rht_dereference_bucket(list->next,
1030 : tbl, hash);
1031 : } while (list && obj != &list->rhead);
1032 :
1033 : if (!list)
1034 : continue;
1035 :
1036 : list = rht_dereference_bucket(list->next, tbl, hash);
1037 : RCU_INIT_POINTER(*lpprev, list);
1038 : err = 0;
1039 : break;
1040 : }
1041 :
1042 : obj = rht_dereference_bucket(obj->next, tbl, hash);
1043 : err = 1;
1044 :
1045 : if (rhlist) {
1046 : list = rht_dereference_bucket(list->next, tbl, hash);
1047 : if (list) {
1048 : RCU_INIT_POINTER(list->rhead.next, obj);
1049 : obj = &list->rhead;
1050 : err = 0;
1051 : }
1052 : }
1053 :
1054 : if (pprev) {
1055 : rcu_assign_pointer(*pprev, obj);
1056 : rht_unlock(tbl, bkt, flags);
1057 : } else {
1058 : rht_assign_unlock(tbl, bkt, obj, flags);
1059 : }
1060 : goto unlocked;
1061 : }
1062 :
1063 : rht_unlock(tbl, bkt, flags);
1064 : unlocked:
1065 : if (err > 0) {
1066 : atomic_dec(&ht->nelems);
1067 : if (unlikely(ht->p.automatic_shrinking &&
1068 : rht_shrink_below_30(ht, tbl)))
1069 : schedule_work(&ht->run_work);
1070 : err = 0;
1071 : }
1072 :
1073 : return err;
1074 : }
1075 :
1076 : /* Internal function, please use rhashtable_remove_fast() instead */
1077 : static inline int __rhashtable_remove_fast(
1078 : struct rhashtable *ht, struct rhash_head *obj,
1079 : const struct rhashtable_params params, bool rhlist)
1080 : {
1081 : struct bucket_table *tbl;
1082 : int err;
1083 :
1084 : rcu_read_lock();
1085 :
1086 : tbl = rht_dereference_rcu(ht->tbl, ht);
1087 :
1088 : /* Because we have already taken (and released) the bucket
1089 : * lock in old_tbl, if we find that future_tbl is not yet
1090 : * visible then that guarantees the entry to still be in
1091 : * the old tbl if it exists.
1092 : */
1093 : while ((err = __rhashtable_remove_fast_one(ht, tbl, obj, params,
1094 : rhlist)) &&
1095 : (tbl = rht_dereference_rcu(tbl->future_tbl, ht)))
1096 : ;
1097 :
1098 : rcu_read_unlock();
1099 :
1100 : return err;
1101 : }
1102 :
1103 : /**
1104 : * rhashtable_remove_fast - remove object from hash table
1105 : * @ht: hash table
1106 : * @obj: pointer to hash head inside object
1107 : * @params: hash table parameters
1108 : *
1109 : * Since the hash chain is single linked, the removal operation needs to
1110 : * walk the bucket chain upon removal. The removal operation is thus
1111 : * considerable slow if the hash table is not correctly sized.
1112 : *
1113 : * Will automatically shrink the table if permitted when residency drops
1114 : * below 30%.
1115 : *
1116 : * Returns zero on success, -ENOENT if the entry could not be found.
1117 : */
1118 : static inline int rhashtable_remove_fast(
1119 : struct rhashtable *ht, struct rhash_head *obj,
1120 : const struct rhashtable_params params)
1121 : {
1122 : return __rhashtable_remove_fast(ht, obj, params, false);
1123 : }
1124 :
1125 : /**
1126 : * rhltable_remove - remove object from hash list table
1127 : * @hlt: hash list table
1128 : * @list: pointer to hash list head inside object
1129 : * @params: hash table parameters
1130 : *
1131 : * Since the hash chain is single linked, the removal operation needs to
1132 : * walk the bucket chain upon removal. The removal operation is thus
1133 : * considerable slow if the hash table is not correctly sized.
1134 : *
1135 : * Will automatically shrink the table if permitted when residency drops
1136 : * below 30%
1137 : *
1138 : * Returns zero on success, -ENOENT if the entry could not be found.
1139 : */
1140 : static inline int rhltable_remove(
1141 : struct rhltable *hlt, struct rhlist_head *list,
1142 : const struct rhashtable_params params)
1143 : {
1144 : return __rhashtable_remove_fast(&hlt->ht, &list->rhead, params, true);
1145 : }
1146 :
1147 : /* Internal function, please use rhashtable_replace_fast() instead */
1148 : static inline int __rhashtable_replace_fast(
1149 : struct rhashtable *ht, struct bucket_table *tbl,
1150 : struct rhash_head *obj_old, struct rhash_head *obj_new,
1151 : const struct rhashtable_params params)
1152 : {
1153 : struct rhash_lock_head __rcu **bkt;
1154 : struct rhash_head __rcu **pprev;
1155 : struct rhash_head *he;
1156 : unsigned long flags;
1157 : unsigned int hash;
1158 : int err = -ENOENT;
1159 :
1160 : /* Minimally, the old and new objects must have same hash
1161 : * (which should mean identifiers are the same).
1162 : */
1163 : hash = rht_head_hashfn(ht, tbl, obj_old, params);
1164 : if (hash != rht_head_hashfn(ht, tbl, obj_new, params))
1165 : return -EINVAL;
1166 :
1167 : bkt = rht_bucket_var(tbl, hash);
1168 : if (!bkt)
1169 : return -ENOENT;
1170 :
1171 : pprev = NULL;
1172 : flags = rht_lock(tbl, bkt);
1173 :
1174 : rht_for_each_from(he, rht_ptr(bkt, tbl, hash), tbl, hash) {
1175 : if (he != obj_old) {
1176 : pprev = &he->next;
1177 : continue;
1178 : }
1179 :
1180 : rcu_assign_pointer(obj_new->next, obj_old->next);
1181 : if (pprev) {
1182 : rcu_assign_pointer(*pprev, obj_new);
1183 : rht_unlock(tbl, bkt, flags);
1184 : } else {
1185 : rht_assign_unlock(tbl, bkt, obj_new, flags);
1186 : }
1187 : err = 0;
1188 : goto unlocked;
1189 : }
1190 :
1191 : rht_unlock(tbl, bkt, flags);
1192 :
1193 : unlocked:
1194 : return err;
1195 : }
1196 :
1197 : /**
1198 : * rhashtable_replace_fast - replace an object in hash table
1199 : * @ht: hash table
1200 : * @obj_old: pointer to hash head inside object being replaced
1201 : * @obj_new: pointer to hash head inside object which is new
1202 : * @params: hash table parameters
1203 : *
1204 : * Replacing an object doesn't affect the number of elements in the hash table
1205 : * or bucket, so we don't need to worry about shrinking or expanding the
1206 : * table here.
1207 : *
1208 : * Returns zero on success, -ENOENT if the entry could not be found,
1209 : * -EINVAL if hash is not the same for the old and new objects.
1210 : */
1211 : static inline int rhashtable_replace_fast(
1212 : struct rhashtable *ht, struct rhash_head *obj_old,
1213 : struct rhash_head *obj_new,
1214 : const struct rhashtable_params params)
1215 : {
1216 : struct bucket_table *tbl;
1217 : int err;
1218 :
1219 : rcu_read_lock();
1220 :
1221 : tbl = rht_dereference_rcu(ht->tbl, ht);
1222 :
1223 : /* Because we have already taken (and released) the bucket
1224 : * lock in old_tbl, if we find that future_tbl is not yet
1225 : * visible then that guarantees the entry to still be in
1226 : * the old tbl if it exists.
1227 : */
1228 : while ((err = __rhashtable_replace_fast(ht, tbl, obj_old,
1229 : obj_new, params)) &&
1230 : (tbl = rht_dereference_rcu(tbl->future_tbl, ht)))
1231 : ;
1232 :
1233 : rcu_read_unlock();
1234 :
1235 : return err;
1236 : }
1237 :
1238 : /**
1239 : * rhltable_walk_enter - Initialise an iterator
1240 : * @hlt: Table to walk over
1241 : * @iter: Hash table Iterator
1242 : *
1243 : * This function prepares a hash table walk.
1244 : *
1245 : * Note that if you restart a walk after rhashtable_walk_stop you
1246 : * may see the same object twice. Also, you may miss objects if
1247 : * there are removals in between rhashtable_walk_stop and the next
1248 : * call to rhashtable_walk_start.
1249 : *
1250 : * For a completely stable walk you should construct your own data
1251 : * structure outside the hash table.
1252 : *
1253 : * This function may be called from any process context, including
1254 : * non-preemptable context, but cannot be called from softirq or
1255 : * hardirq context.
1256 : *
1257 : * You must call rhashtable_walk_exit after this function returns.
1258 : */
1259 : static inline void rhltable_walk_enter(struct rhltable *hlt,
1260 : struct rhashtable_iter *iter)
1261 : {
1262 : return rhashtable_walk_enter(&hlt->ht, iter);
1263 : }
1264 :
1265 : /**
1266 : * rhltable_free_and_destroy - free elements and destroy hash list table
1267 : * @hlt: the hash list table to destroy
1268 : * @free_fn: callback to release resources of element
1269 : * @arg: pointer passed to free_fn
1270 : *
1271 : * See documentation for rhashtable_free_and_destroy.
1272 : */
1273 : static inline void rhltable_free_and_destroy(struct rhltable *hlt,
1274 : void (*free_fn)(void *ptr,
1275 : void *arg),
1276 : void *arg)
1277 : {
1278 : return rhashtable_free_and_destroy(&hlt->ht, free_fn, arg);
1279 : }
1280 :
1281 : static inline void rhltable_destroy(struct rhltable *hlt)
1282 : {
1283 : return rhltable_free_and_destroy(hlt, NULL, NULL);
1284 : }
1285 :
1286 : #endif /* _LINUX_RHASHTABLE_H */
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