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 | 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 | 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 | return hash & (tbl->size - 1); |
123 | } |
124 | |
125 | 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 | if (!__builtin_constant_p(params.key_len)) |
133 | hash = ht->p.hashfn(key, ht->key_len, hash_rnd); |
134 | else if (params.key_len) { |
135 | unsigned int key_len = params.key_len; |
136 | |
137 | if (params.hashfn) |
138 | hash = params.hashfn(key, key_len, hash_rnd); |
139 | else if (key_len & (sizeof(u32) - 1)) |
140 | hash = jhash(key, length: key_len, initval: hash_rnd); |
141 | else |
142 | hash = jhash2(k: key, length: key_len / sizeof(u32), initval: hash_rnd); |
143 | } else { |
144 | unsigned int key_len = ht->p.key_len; |
145 | |
146 | if (params.hashfn) |
147 | hash = params.hashfn(key, key_len, hash_rnd); |
148 | else |
149 | hash = jhash(key, length: key_len, initval: hash_rnd); |
150 | } |
151 | |
152 | 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 | unsigned int hash = rht_key_get_hash(ht, key, params, hash_rnd: tbl->hash_rnd); |
160 | |
161 | return rht_bucket_index(tbl, hash); |
162 | } |
163 | |
164 | 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 | const char *ptr = rht_obj(ht, he); |
169 | |
170 | return likely(params.obj_hashfn) ? |
171 | rht_bucket_index(tbl, hash: params.obj_hashfn(ptr, params.key_len ?: |
172 | ht->p.key_len, |
173 | tbl->hash_rnd)) : |
174 | rht_key_hashfn(ht, tbl, key: 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 | return atomic_read(v: &ht->nelems) > (tbl->size / 4 * 3) && |
187 | (!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 | return atomic_read(v: &ht->nelems) < (tbl->size * 3 / 10) && |
200 | 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 | return atomic_read(v: &ht->nelems) > tbl->size && |
212 | (!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 | return atomic_read(v: &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 | static inline struct rhash_lock_head __rcu *const *rht_bucket( |
287 | const struct bucket_table *tbl, unsigned int hash) |
288 | { |
289 | 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 | 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 | 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 | local_irq_save(flags); |
332 | bit_spin_lock(bitnum: 0, addr: (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 | local_irq_save(flags); |
344 | bit_spin_lock(bitnum: 0, addr: (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 | bit_spin_unlock(bitnum: 0, addr: (unsigned long *)bkt); |
355 | 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 | return (struct rhash_head *) |
362 | ((unsigned long)p & ~BIT(0) ?: |
363 | (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 | 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 | 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 | 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 | if (rht_is_a_nulls(ptr: obj)) |
397 | obj = NULL; |
398 | 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 | if (rht_is_a_nulls(ptr: obj)) |
407 | obj = NULL; |
408 | lock_map_release(&tbl->dep_map); |
409 | rcu_assign_pointer(*bkt, (void *)obj); |
410 | preempt_enable(); |
411 | __release(bitlock); |
412 | 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 | struct rhashtable *ht = arg->ht; |
583 | const char *ptr = obj; |
584 | |
585 | return memcmp(p: ptr + ht->p.key_offset, q: arg->key, size: 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: &arg, obj: 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(ht: &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, he: obj, params); |
726 | elasticity = RHT_ELASTICITY; |
727 | bkt = rht_bucket_insert(ht, tbl, hash); |
728 | data = ERR_PTR(error: -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, he: head)) : |
749 | rhashtable_compare(arg: &arg, obj: rht_obj(ht, he: head)))) { |
750 | pprev = &head->next; |
751 | continue; |
752 | } |
753 | |
754 | data = rht_obj(ht, he: 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(error: -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(v: &ht->nelems); |
797 | rht_assign_unlock(tbl, bkt, obj, flags); |
798 | |
799 | if (rht_grow_above_75(ht, tbl)) |
800 | schedule_work(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, rhlist: false); |
835 | if (IS_ERR(ptr: ret)) |
836 | return PTR_ERR(ptr: 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(ptr: __rhashtable_insert_fast(ht: &hlt->ht, key, obj: &list->rhead, |
862 | params, rhlist: 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(ht: &hlt->ht, he: &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, he: obj); |
910 | void *ret; |
911 | |
912 | BUG_ON(ht->p.obj_hashfn); |
913 | |
914 | ret = __rhashtable_insert_fast(ht, key: key + ht->p.key_offset, obj, params, |
915 | rhlist: false); |
916 | if (IS_ERR(ptr: ret)) |
917 | return PTR_ERR(ptr: 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, he: obj); |
937 | |
938 | BUG_ON(ht->p.obj_hashfn); |
939 | |
940 | return __rhashtable_insert_fast(ht, key: key + ht->p.key_offset, obj, params, |
941 | rhlist: 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, rhlist: false); |
968 | if (IS_ERR(ptr: ret)) |
969 | return PTR_ERR(ptr: 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, rhlist: 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, he: 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(v: &ht->nelems); |
1067 | if (unlikely(ht->p.automatic_shrinking && |
1068 | rht_shrink_below_30(ht, tbl))) |
1069 | schedule_work(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, rhlist: 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(ht: &hlt->ht, obj: &list->rhead, params, rhlist: 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, he: obj_old, params); |
1164 | if (hash != rht_head_hashfn(ht, tbl, he: 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: 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(ht: &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(ht: &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 */ |
1287 | |