1 /* SPDX-License-Identifier: GPL-2.0 */
3 * Resizable, Scalable, Concurrent Hash Table
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>
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
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.
18 #ifndef _LINUX_RHASHTABLE_H
19 #define _LINUX_RHASHTABLE_H
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>
29 #include <linux/rhashtable-types.h>
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
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.
47 struct rhash_lock_head
{};
49 /* Maximum chain length before rehash
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).
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).
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.
62 #define RHT_ELASTICITY 16u
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
80 struct list_head walkers
;
83 struct bucket_table __rcu
*future_tbl
;
85 struct lockdep_map dep_map
;
87 struct rhash_lock_head __rcu
*buckets
[] ____cacheline_aligned_in_smp
;
91 * NULLS_MARKER() expects a hash value with the low
92 * bits mostly likely to be significant, and it discards
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.
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
103 #define RHT_NULLS_MARKER(ptr) \
104 ((void *)NULLS_MARKER(((unsigned long) (ptr)) >> 1))
105 #define INIT_RHT_NULLS_HEAD(ptr) \
108 static inline bool rht_is_a_nulls(const struct rhash_head
*ptr
)
110 return ((unsigned long) ptr
& 1);
113 static inline void *rht_obj(const struct rhashtable
*ht
,
114 const struct rhash_head
*he
)
116 return (char *)he
- ht
->p
.head_offset
;
119 static inline unsigned int rht_bucket_index(const struct bucket_table
*tbl
,
122 return hash
& (tbl
->size
- 1);
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
)
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
;
138 hash
= params
.hashfn(key
, key_len
, hash_rnd
);
139 else if (key_len
& (sizeof(u32
) - 1))
140 hash
= jhash(key
, key_len
, hash_rnd
);
142 hash
= jhash2(key
, key_len
/ sizeof(u32
), hash_rnd
);
144 unsigned int key_len
= ht
->p
.key_len
;
147 hash
= params
.hashfn(key
, key_len
, hash_rnd
);
149 hash
= jhash(key
, key_len
, hash_rnd
);
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
)
159 unsigned int hash
= rht_key_get_hash(ht
, key
, params
, tbl
->hash_rnd
);
161 return rht_bucket_index(tbl
, hash
);
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
)
168 const char *ptr
= rht_obj(ht
, he
);
170 return likely(params
.obj_hashfn
) ?
171 rht_bucket_index(tbl
, params
.obj_hashfn(ptr
, params
.key_len
?:
174 rht_key_hashfn(ht
, tbl
, ptr
+ params
.key_offset
, params
);
178 * rht_grow_above_75 - returns true if nelems > 0.75 * table-size
180 * @tbl: current table
182 static inline bool rht_grow_above_75(const struct rhashtable
*ht
,
183 const struct bucket_table
*tbl
)
185 /* Expand table when exceeding 75% load */
186 return atomic_read(&ht
->nelems
) > (tbl
->size
/ 4 * 3) &&
187 (!ht
->p
.max_size
|| tbl
->size
< ht
->p
.max_size
);
191 * rht_shrink_below_30 - returns true if nelems < 0.3 * table-size
193 * @tbl: current table
195 static inline bool rht_shrink_below_30(const struct rhashtable
*ht
,
196 const struct bucket_table
*tbl
)
198 /* Shrink table beneath 30% load */
199 return atomic_read(&ht
->nelems
) < (tbl
->size
* 3 / 10) &&
200 tbl
->size
> ht
->p
.min_size
;
204 * rht_grow_above_100 - returns true if nelems > table-size
206 * @tbl: current table
208 static inline bool rht_grow_above_100(const struct rhashtable
*ht
,
209 const struct bucket_table
*tbl
)
211 return atomic_read(&ht
->nelems
) > tbl
->size
&&
212 (!ht
->p
.max_size
|| tbl
->size
< ht
->p
.max_size
);
216 * rht_grow_above_max - returns true if table is above maximum
218 * @tbl: current table
220 static inline bool rht_grow_above_max(const struct rhashtable
*ht
,
221 const struct bucket_table
*tbl
)
223 return atomic_read(&ht
->nelems
) >= ht
->max_elems
;
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
);
230 static inline int lockdep_rht_mutex_is_held(struct rhashtable
*ht
)
235 static inline int lockdep_rht_bucket_is_held(const struct bucket_table
*tbl
,
240 #endif /* CONFIG_PROVE_LOCKING */
242 void *rhashtable_insert_slow(struct rhashtable
*ht
, const void *key
,
243 struct rhash_head
*obj
);
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
);
250 static inline void rhashtable_walk_start(struct rhashtable_iter
*iter
)
252 (void)rhashtable_walk_start_check(iter
);
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
);
259 void rhashtable_free_and_destroy(struct rhashtable
*ht
,
260 void (*free_fn
)(void *ptr
, void *arg
),
262 void rhashtable_destroy(struct rhashtable
*ht
);
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
);
271 #define rht_dereference(p, ht) \
272 rcu_dereference_protected(p, lockdep_rht_mutex_is_held(ht))
274 #define rht_dereference_rcu(p, ht) \
275 rcu_dereference_check(p, lockdep_rht_mutex_is_held(ht))
277 #define rht_dereference_bucket(p, tbl, hash) \
278 rcu_dereference_protected(p, lockdep_rht_bucket_is_held(tbl, hash))
280 #define rht_dereference_bucket_rcu(p, tbl, hash) \
281 rcu_dereference_check(p, lockdep_rht_bucket_is_held(tbl, hash))
283 #define rht_entry(tpos, pos, member) \
284 ({ tpos = container_of(pos, typeof(*tpos), member); 1; })
286 static inline struct rhash_lock_head __rcu
*const *rht_bucket(
287 const struct bucket_table
*tbl
, unsigned int hash
)
289 return unlikely(tbl
->nest
) ? rht_bucket_nested(tbl
, hash
) :
293 static inline struct rhash_lock_head __rcu
**rht_bucket_var(
294 struct bucket_table
*tbl
, unsigned int hash
)
296 return unlikely(tbl
->nest
) ? __rht_bucket_nested(tbl
, hash
) :
300 static inline struct rhash_lock_head __rcu
**rht_bucket_insert(
301 struct rhashtable
*ht
, struct bucket_table
*tbl
, unsigned int hash
)
303 return unlikely(tbl
->nest
) ? rht_bucket_nested_insert(ht
, tbl
, hash
) :
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,
323 * When we write to a bucket without unlocking, we use rht_assign_locked().
326 static inline void rht_lock(struct bucket_table
*tbl
,
327 struct rhash_lock_head __rcu
**bkt
)
330 bit_spin_lock(0, (unsigned long *)bkt
);
331 lock_map_acquire(&tbl
->dep_map
);
334 static inline void rht_lock_nested(struct bucket_table
*tbl
,
335 struct rhash_lock_head __rcu
**bucket
,
336 unsigned int subclass
)
339 bit_spin_lock(0, (unsigned long *)bucket
);
340 lock_acquire_exclusive(&tbl
->dep_map
, subclass
, 0, NULL
, _THIS_IP_
);
343 static inline void rht_unlock(struct bucket_table
*tbl
,
344 struct rhash_lock_head __rcu
**bkt
)
346 lock_map_release(&tbl
->dep_map
);
347 bit_spin_unlock(0, (unsigned long *)bkt
);
351 static inline struct rhash_head
*__rht_ptr(
352 struct rhash_lock_head
*p
, struct rhash_lock_head __rcu
*const *bkt
)
354 return (struct rhash_head
*)
355 ((unsigned long)p
& ~BIT(0) ?:
356 (unsigned long)RHT_NULLS_MARKER(bkt
));
360 * Where 'bkt' is a bucket and might be locked:
361 * rht_ptr_rcu() dereferences that pointer and clears the lock bit.
362 * rht_ptr() dereferences in a context where the bucket is locked.
363 * rht_ptr_exclusive() dereferences in a context where exclusive
364 * access is guaranteed, such as when destroying the table.
366 static inline struct rhash_head
*rht_ptr_rcu(
367 struct rhash_lock_head __rcu
*const *bkt
)
369 return __rht_ptr(rcu_dereference(*bkt
), bkt
);
372 static inline struct rhash_head
*rht_ptr(
373 struct rhash_lock_head __rcu
*const *bkt
,
374 struct bucket_table
*tbl
,
377 return __rht_ptr(rht_dereference_bucket(*bkt
, tbl
, hash
), bkt
);
380 static inline struct rhash_head
*rht_ptr_exclusive(
381 struct rhash_lock_head __rcu
*const *bkt
)
383 return __rht_ptr(rcu_dereference_protected(*bkt
, 1), bkt
);
386 static inline void rht_assign_locked(struct rhash_lock_head __rcu
**bkt
,
387 struct rhash_head
*obj
)
389 if (rht_is_a_nulls(obj
))
391 rcu_assign_pointer(*bkt
, (void *)((unsigned long)obj
| BIT(0)));
394 static inline void rht_assign_unlock(struct bucket_table
*tbl
,
395 struct rhash_lock_head __rcu
**bkt
,
396 struct rhash_head
*obj
)
398 if (rht_is_a_nulls(obj
))
400 lock_map_release(&tbl
->dep_map
);
401 rcu_assign_pointer(*bkt
, (void *)obj
);
408 * rht_for_each_from - iterate over hash chain from given head
409 * @pos: the &struct rhash_head to use as a loop cursor.
410 * @head: the &struct rhash_head to start from
411 * @tbl: the &struct bucket_table
412 * @hash: the hash value / bucket index
414 #define rht_for_each_from(pos, head, tbl, hash) \
416 !rht_is_a_nulls(pos); \
417 pos = rht_dereference_bucket((pos)->next, tbl, hash))
420 * rht_for_each - iterate over hash chain
421 * @pos: the &struct rhash_head to use as a loop cursor.
422 * @tbl: the &struct bucket_table
423 * @hash: the hash value / bucket index
425 #define rht_for_each(pos, tbl, hash) \
426 rht_for_each_from(pos, rht_ptr(rht_bucket(tbl, hash), tbl, hash), \
430 * rht_for_each_entry_from - iterate over hash chain from given head
431 * @tpos: the type * to use as a loop cursor.
432 * @pos: the &struct rhash_head to use as a loop cursor.
433 * @head: the &struct rhash_head to start from
434 * @tbl: the &struct bucket_table
435 * @hash: the hash value / bucket index
436 * @member: name of the &struct rhash_head within the hashable struct.
438 #define rht_for_each_entry_from(tpos, pos, head, tbl, hash, member) \
440 (!rht_is_a_nulls(pos)) && rht_entry(tpos, pos, member); \
441 pos = rht_dereference_bucket((pos)->next, tbl, hash))
444 * rht_for_each_entry - iterate over hash chain of given type
445 * @tpos: the type * to use as a loop cursor.
446 * @pos: the &struct rhash_head to use as a loop cursor.
447 * @tbl: the &struct bucket_table
448 * @hash: the hash value / bucket index
449 * @member: name of the &struct rhash_head within the hashable struct.
451 #define rht_for_each_entry(tpos, pos, tbl, hash, member) \
452 rht_for_each_entry_from(tpos, pos, \
453 rht_ptr(rht_bucket(tbl, hash), tbl, hash), \
457 * rht_for_each_entry_safe - safely iterate over hash chain of given type
458 * @tpos: the type * to use as a loop cursor.
459 * @pos: the &struct rhash_head to use as a loop cursor.
460 * @next: the &struct rhash_head to use as next in loop cursor.
461 * @tbl: the &struct bucket_table
462 * @hash: the hash value / bucket index
463 * @member: name of the &struct rhash_head within the hashable struct.
465 * This hash chain list-traversal primitive allows for the looped code to
466 * remove the loop cursor from the list.
468 #define rht_for_each_entry_safe(tpos, pos, next, tbl, hash, member) \
469 for (pos = rht_ptr(rht_bucket(tbl, hash), tbl, hash), \
470 next = !rht_is_a_nulls(pos) ? \
471 rht_dereference_bucket(pos->next, tbl, hash) : NULL; \
472 (!rht_is_a_nulls(pos)) && rht_entry(tpos, pos, member); \
474 next = !rht_is_a_nulls(pos) ? \
475 rht_dereference_bucket(pos->next, tbl, hash) : NULL)
478 * rht_for_each_rcu_from - iterate over rcu hash chain from given head
479 * @pos: the &struct rhash_head to use as a loop cursor.
480 * @head: the &struct rhash_head to start from
481 * @tbl: the &struct bucket_table
482 * @hash: the hash value / bucket index
484 * This hash chain list-traversal primitive may safely run concurrently with
485 * the _rcu mutation primitives such as rhashtable_insert() as long as the
486 * traversal is guarded by rcu_read_lock().
488 #define rht_for_each_rcu_from(pos, head, tbl, hash) \
489 for (({barrier(); }), \
491 !rht_is_a_nulls(pos); \
492 pos = rcu_dereference_raw(pos->next))
495 * rht_for_each_rcu - iterate over rcu hash chain
496 * @pos: the &struct rhash_head to use as a loop cursor.
497 * @tbl: the &struct bucket_table
498 * @hash: the hash value / bucket index
500 * This hash chain list-traversal primitive may safely run concurrently with
501 * the _rcu mutation primitives such as rhashtable_insert() as long as the
502 * traversal is guarded by rcu_read_lock().
504 #define rht_for_each_rcu(pos, tbl, hash) \
505 for (({barrier(); }), \
506 pos = rht_ptr_rcu(rht_bucket(tbl, hash)); \
507 !rht_is_a_nulls(pos); \
508 pos = rcu_dereference_raw(pos->next))
511 * rht_for_each_entry_rcu_from - iterated over rcu hash chain from given head
512 * @tpos: the type * to use as a loop cursor.
513 * @pos: the &struct rhash_head to use as a loop cursor.
514 * @head: the &struct rhash_head to start from
515 * @tbl: the &struct bucket_table
516 * @hash: the hash value / bucket index
517 * @member: name of the &struct rhash_head within the hashable struct.
519 * This hash chain list-traversal primitive may safely run concurrently with
520 * the _rcu mutation primitives such as rhashtable_insert() as long as the
521 * traversal is guarded by rcu_read_lock().
523 #define rht_for_each_entry_rcu_from(tpos, pos, head, tbl, hash, member) \
524 for (({barrier(); }), \
526 (!rht_is_a_nulls(pos)) && rht_entry(tpos, pos, member); \
527 pos = rht_dereference_bucket_rcu(pos->next, tbl, hash))
530 * rht_for_each_entry_rcu - iterate over rcu hash chain of given type
531 * @tpos: the type * to use as a loop cursor.
532 * @pos: the &struct rhash_head to use as a loop cursor.
533 * @tbl: the &struct bucket_table
534 * @hash: the hash value / bucket index
535 * @member: name of the &struct rhash_head within the hashable struct.
537 * This hash chain list-traversal primitive may safely run concurrently with
538 * the _rcu mutation primitives such as rhashtable_insert() as long as the
539 * traversal is guarded by rcu_read_lock().
541 #define rht_for_each_entry_rcu(tpos, pos, tbl, hash, member) \
542 rht_for_each_entry_rcu_from(tpos, pos, \
543 rht_ptr_rcu(rht_bucket(tbl, hash)), \
547 * rhl_for_each_rcu - iterate over rcu hash table list
548 * @pos: the &struct rlist_head to use as a loop cursor.
549 * @list: the head of the list
551 * This hash chain list-traversal primitive should be used on the
552 * list returned by rhltable_lookup.
554 #define rhl_for_each_rcu(pos, list) \
555 for (pos = list; pos; pos = rcu_dereference_raw(pos->next))
558 * rhl_for_each_entry_rcu - iterate over rcu hash table list of given type
559 * @tpos: the type * to use as a loop cursor.
560 * @pos: the &struct rlist_head to use as a loop cursor.
561 * @list: the head of the list
562 * @member: name of the &struct rlist_head within the hashable struct.
564 * This hash chain list-traversal primitive should be used on the
565 * list returned by rhltable_lookup.
567 #define rhl_for_each_entry_rcu(tpos, pos, list, member) \
568 for (pos = list; pos && rht_entry(tpos, pos, member); \
569 pos = rcu_dereference_raw(pos->next))
571 static inline int rhashtable_compare(struct rhashtable_compare_arg
*arg
,
574 struct rhashtable
*ht
= arg
->ht
;
575 const char *ptr
= obj
;
577 return memcmp(ptr
+ ht
->p
.key_offset
, arg
->key
, ht
->p
.key_len
);
580 /* Internal function, do not use. */
581 static inline struct rhash_head
*__rhashtable_lookup(
582 struct rhashtable
*ht
, const void *key
,
583 const struct rhashtable_params params
)
585 struct rhashtable_compare_arg arg
= {
589 struct rhash_lock_head __rcu
*const *bkt
;
590 struct bucket_table
*tbl
;
591 struct rhash_head
*he
;
594 tbl
= rht_dereference_rcu(ht
->tbl
, ht
);
596 hash
= rht_key_hashfn(ht
, tbl
, key
, params
);
597 bkt
= rht_bucket(tbl
, hash
);
599 rht_for_each_rcu_from(he
, rht_ptr_rcu(bkt
), tbl
, hash
) {
600 if (params
.obj_cmpfn
?
601 params
.obj_cmpfn(&arg
, rht_obj(ht
, he
)) :
602 rhashtable_compare(&arg
, rht_obj(ht
, he
)))
606 /* An object might have been moved to a different hash chain,
607 * while we walk along it - better check and retry.
609 } while (he
!= RHT_NULLS_MARKER(bkt
));
611 /* Ensure we see any new tables. */
614 tbl
= rht_dereference_rcu(tbl
->future_tbl
, ht
);
622 * rhashtable_lookup - search hash table
624 * @key: the pointer to the key
625 * @params: hash table parameters
627 * Computes the hash value for the key and traverses the bucket chain looking
628 * for a entry with an identical key. The first matching entry is returned.
630 * This must only be called under the RCU read lock.
632 * Returns the first entry on which the compare function returned true.
634 static inline void *rhashtable_lookup(
635 struct rhashtable
*ht
, const void *key
,
636 const struct rhashtable_params params
)
638 struct rhash_head
*he
= __rhashtable_lookup(ht
, key
, params
);
640 return he
? rht_obj(ht
, he
) : NULL
;
644 * rhashtable_lookup_fast - search hash table, without RCU read lock
646 * @key: the pointer to the key
647 * @params: hash table parameters
649 * Computes the hash value for the key and traverses the bucket chain looking
650 * for a entry with an identical key. The first matching entry is returned.
652 * Only use this function when you have other mechanisms guaranteeing
653 * that the object won't go away after the RCU read lock is released.
655 * Returns the first entry on which the compare function returned true.
657 static inline void *rhashtable_lookup_fast(
658 struct rhashtable
*ht
, const void *key
,
659 const struct rhashtable_params params
)
664 obj
= rhashtable_lookup(ht
, key
, params
);
671 * rhltable_lookup - search hash list table
673 * @key: the pointer to the key
674 * @params: hash table parameters
676 * Computes the hash value for the key and traverses the bucket chain looking
677 * for a entry with an identical key. All matching entries are returned
680 * This must only be called under the RCU read lock.
682 * Returns the list of entries that match the given key.
684 static inline struct rhlist_head
*rhltable_lookup(
685 struct rhltable
*hlt
, const void *key
,
686 const struct rhashtable_params params
)
688 struct rhash_head
*he
= __rhashtable_lookup(&hlt
->ht
, key
, params
);
690 return he
? container_of(he
, struct rhlist_head
, rhead
) : NULL
;
693 /* Internal function, please use rhashtable_insert_fast() instead. This
694 * function returns the existing element already in hashes in there is a clash,
695 * otherwise it returns an error via ERR_PTR().
697 static inline void *__rhashtable_insert_fast(
698 struct rhashtable
*ht
, const void *key
, struct rhash_head
*obj
,
699 const struct rhashtable_params params
, bool rhlist
)
701 struct rhashtable_compare_arg arg
= {
705 struct rhash_lock_head __rcu
**bkt
;
706 struct rhash_head __rcu
**pprev
;
707 struct bucket_table
*tbl
;
708 struct rhash_head
*head
;
715 tbl
= rht_dereference_rcu(ht
->tbl
, ht
);
716 hash
= rht_head_hashfn(ht
, tbl
, obj
, params
);
717 elasticity
= RHT_ELASTICITY
;
718 bkt
= rht_bucket_insert(ht
, tbl
, hash
);
719 data
= ERR_PTR(-ENOMEM
);
725 if (unlikely(rcu_access_pointer(tbl
->future_tbl
))) {
727 rht_unlock(tbl
, bkt
);
729 return rhashtable_insert_slow(ht
, key
, obj
);
732 rht_for_each_from(head
, rht_ptr(bkt
, tbl
, hash
), tbl
, hash
) {
733 struct rhlist_head
*plist
;
734 struct rhlist_head
*list
;
739 params
.obj_cmpfn(&arg
, rht_obj(ht
, head
)) :
740 rhashtable_compare(&arg
, rht_obj(ht
, head
)))) {
745 data
= rht_obj(ht
, head
);
751 list
= container_of(obj
, struct rhlist_head
, rhead
);
752 plist
= container_of(head
, struct rhlist_head
, rhead
);
754 RCU_INIT_POINTER(list
->next
, plist
);
755 head
= rht_dereference_bucket(head
->next
, tbl
, hash
);
756 RCU_INIT_POINTER(list
->rhead
.next
, head
);
758 rcu_assign_pointer(*pprev
, obj
);
759 rht_unlock(tbl
, bkt
);
761 rht_assign_unlock(tbl
, bkt
, obj
);
769 data
= ERR_PTR(-E2BIG
);
770 if (unlikely(rht_grow_above_max(ht
, tbl
)))
773 if (unlikely(rht_grow_above_100(ht
, tbl
)))
776 /* Inserting at head of list makes unlocking free. */
777 head
= rht_ptr(bkt
, tbl
, hash
);
779 RCU_INIT_POINTER(obj
->next
, head
);
781 struct rhlist_head
*list
;
783 list
= container_of(obj
, struct rhlist_head
, rhead
);
784 RCU_INIT_POINTER(list
->next
, NULL
);
787 atomic_inc(&ht
->nelems
);
788 rht_assign_unlock(tbl
, bkt
, obj
);
790 if (rht_grow_above_75(ht
, tbl
))
791 schedule_work(&ht
->run_work
);
800 rht_unlock(tbl
, bkt
);
805 * rhashtable_insert_fast - insert object into hash table
807 * @obj: pointer to hash head inside object
808 * @params: hash table parameters
810 * Will take the per bucket bitlock to protect against mutual mutations
811 * on the same bucket. Multiple insertions may occur in parallel unless
812 * they map to the same bucket.
814 * It is safe to call this function from atomic context.
816 * Will trigger an automatic deferred table resizing if residency in the
817 * table grows beyond 70%.
819 static inline int rhashtable_insert_fast(
820 struct rhashtable
*ht
, struct rhash_head
*obj
,
821 const struct rhashtable_params params
)
825 ret
= __rhashtable_insert_fast(ht
, NULL
, obj
, params
, false);
829 return ret
== NULL
? 0 : -EEXIST
;
833 * rhltable_insert_key - insert object into hash list table
834 * @hlt: hash list table
835 * @key: the pointer to the key
836 * @list: pointer to hash list head inside object
837 * @params: hash table parameters
839 * Will take the per bucket bitlock to protect against mutual mutations
840 * on the same bucket. Multiple insertions may occur in parallel unless
841 * they map to the same bucket.
843 * It is safe to call this function from atomic context.
845 * Will trigger an automatic deferred table resizing if residency in the
846 * table grows beyond 70%.
848 static inline int rhltable_insert_key(
849 struct rhltable
*hlt
, const void *key
, struct rhlist_head
*list
,
850 const struct rhashtable_params params
)
852 return PTR_ERR(__rhashtable_insert_fast(&hlt
->ht
, key
, &list
->rhead
,
857 * rhltable_insert - insert object into hash list table
858 * @hlt: hash list table
859 * @list: pointer to hash list head inside object
860 * @params: hash table parameters
862 * Will take the per bucket bitlock to protect against mutual mutations
863 * on the same bucket. Multiple insertions may occur in parallel unless
864 * they map to the same bucket.
866 * It is safe to call this function from atomic context.
868 * Will trigger an automatic deferred table resizing if residency in the
869 * table grows beyond 70%.
871 static inline int rhltable_insert(
872 struct rhltable
*hlt
, struct rhlist_head
*list
,
873 const struct rhashtable_params params
)
875 const char *key
= rht_obj(&hlt
->ht
, &list
->rhead
);
877 key
+= params
.key_offset
;
879 return rhltable_insert_key(hlt
, key
, list
, params
);
883 * rhashtable_lookup_insert_fast - lookup and insert object into hash table
885 * @obj: pointer to hash head inside object
886 * @params: hash table parameters
888 * This lookup function may only be used for fixed key hash table (key_len
889 * parameter set). It will BUG() if used inappropriately.
891 * It is safe to call this function from atomic context.
893 * Will trigger an automatic deferred table resizing if residency in the
894 * table grows beyond 70%.
896 static inline int rhashtable_lookup_insert_fast(
897 struct rhashtable
*ht
, struct rhash_head
*obj
,
898 const struct rhashtable_params params
)
900 const char *key
= rht_obj(ht
, obj
);
903 BUG_ON(ht
->p
.obj_hashfn
);
905 ret
= __rhashtable_insert_fast(ht
, key
+ ht
->p
.key_offset
, obj
, params
,
910 return ret
== NULL
? 0 : -EEXIST
;
914 * rhashtable_lookup_get_insert_fast - lookup and insert object into hash table
916 * @obj: pointer to hash head inside object
917 * @params: hash table parameters
919 * Just like rhashtable_lookup_insert_fast(), but this function returns the
920 * object if it exists, NULL if it did not and the insertion was successful,
921 * and an ERR_PTR otherwise.
923 static inline void *rhashtable_lookup_get_insert_fast(
924 struct rhashtable
*ht
, struct rhash_head
*obj
,
925 const struct rhashtable_params params
)
927 const char *key
= rht_obj(ht
, obj
);
929 BUG_ON(ht
->p
.obj_hashfn
);
931 return __rhashtable_insert_fast(ht
, key
+ ht
->p
.key_offset
, obj
, params
,
936 * rhashtable_lookup_insert_key - search and insert object to hash table
940 * @obj: pointer to hash head inside object
941 * @params: hash table parameters
943 * Lookups may occur in parallel with hashtable mutations and resizing.
945 * Will trigger an automatic deferred table resizing if residency in the
946 * table grows beyond 70%.
948 * Returns zero on success.
950 static inline int rhashtable_lookup_insert_key(
951 struct rhashtable
*ht
, const void *key
, struct rhash_head
*obj
,
952 const struct rhashtable_params params
)
956 BUG_ON(!ht
->p
.obj_hashfn
|| !key
);
958 ret
= __rhashtable_insert_fast(ht
, key
, obj
, params
, false);
962 return ret
== NULL
? 0 : -EEXIST
;
966 * rhashtable_lookup_get_insert_key - lookup and insert object into hash table
969 * @obj: pointer to hash head inside object
970 * @params: hash table parameters
972 * Just like rhashtable_lookup_insert_key(), but this function returns the
973 * object if it exists, NULL if it does not and the insertion was successful,
974 * and an ERR_PTR otherwise.
976 static inline void *rhashtable_lookup_get_insert_key(
977 struct rhashtable
*ht
, const void *key
, struct rhash_head
*obj
,
978 const struct rhashtable_params params
)
980 BUG_ON(!ht
->p
.obj_hashfn
|| !key
);
982 return __rhashtable_insert_fast(ht
, key
, obj
, params
, false);
985 /* Internal function, please use rhashtable_remove_fast() instead */
986 static inline int __rhashtable_remove_fast_one(
987 struct rhashtable
*ht
, struct bucket_table
*tbl
,
988 struct rhash_head
*obj
, const struct rhashtable_params params
,
991 struct rhash_lock_head __rcu
**bkt
;
992 struct rhash_head __rcu
**pprev
;
993 struct rhash_head
*he
;
997 hash
= rht_head_hashfn(ht
, tbl
, obj
, params
);
998 bkt
= rht_bucket_var(tbl
, hash
);
1004 rht_for_each_from(he
, rht_ptr(bkt
, tbl
, hash
), tbl
, hash
) {
1005 struct rhlist_head
*list
;
1007 list
= container_of(he
, struct rhlist_head
, rhead
);
1010 struct rhlist_head __rcu
**lpprev
;
1018 lpprev
= &list
->next
;
1019 list
= rht_dereference_bucket(list
->next
,
1021 } while (list
&& obj
!= &list
->rhead
);
1026 list
= rht_dereference_bucket(list
->next
, tbl
, hash
);
1027 RCU_INIT_POINTER(*lpprev
, list
);
1032 obj
= rht_dereference_bucket(obj
->next
, tbl
, hash
);
1036 list
= rht_dereference_bucket(list
->next
, tbl
, hash
);
1038 RCU_INIT_POINTER(list
->rhead
.next
, obj
);
1045 rcu_assign_pointer(*pprev
, obj
);
1046 rht_unlock(tbl
, bkt
);
1048 rht_assign_unlock(tbl
, bkt
, obj
);
1053 rht_unlock(tbl
, bkt
);
1056 atomic_dec(&ht
->nelems
);
1057 if (unlikely(ht
->p
.automatic_shrinking
&&
1058 rht_shrink_below_30(ht
, tbl
)))
1059 schedule_work(&ht
->run_work
);
1066 /* Internal function, please use rhashtable_remove_fast() instead */
1067 static inline int __rhashtable_remove_fast(
1068 struct rhashtable
*ht
, struct rhash_head
*obj
,
1069 const struct rhashtable_params params
, bool rhlist
)
1071 struct bucket_table
*tbl
;
1076 tbl
= rht_dereference_rcu(ht
->tbl
, ht
);
1078 /* Because we have already taken (and released) the bucket
1079 * lock in old_tbl, if we find that future_tbl is not yet
1080 * visible then that guarantees the entry to still be in
1081 * the old tbl if it exists.
1083 while ((err
= __rhashtable_remove_fast_one(ht
, tbl
, obj
, params
,
1085 (tbl
= rht_dereference_rcu(tbl
->future_tbl
, ht
)))
1094 * rhashtable_remove_fast - remove object from hash table
1096 * @obj: pointer to hash head inside object
1097 * @params: hash table parameters
1099 * Since the hash chain is single linked, the removal operation needs to
1100 * walk the bucket chain upon removal. The removal operation is thus
1101 * considerable slow if the hash table is not correctly sized.
1103 * Will automatically shrink the table if permitted when residency drops
1106 * Returns zero on success, -ENOENT if the entry could not be found.
1108 static inline int rhashtable_remove_fast(
1109 struct rhashtable
*ht
, struct rhash_head
*obj
,
1110 const struct rhashtable_params params
)
1112 return __rhashtable_remove_fast(ht
, obj
, params
, false);
1116 * rhltable_remove - remove object from hash list table
1117 * @hlt: hash list table
1118 * @list: pointer to hash list head inside object
1119 * @params: hash table parameters
1121 * Since the hash chain is single linked, the removal operation needs to
1122 * walk the bucket chain upon removal. The removal operation is thus
1123 * considerable slow if the hash table is not correctly sized.
1125 * Will automatically shrink the table if permitted when residency drops
1128 * Returns zero on success, -ENOENT if the entry could not be found.
1130 static inline int rhltable_remove(
1131 struct rhltable
*hlt
, struct rhlist_head
*list
,
1132 const struct rhashtable_params params
)
1134 return __rhashtable_remove_fast(&hlt
->ht
, &list
->rhead
, params
, true);
1137 /* Internal function, please use rhashtable_replace_fast() instead */
1138 static inline int __rhashtable_replace_fast(
1139 struct rhashtable
*ht
, struct bucket_table
*tbl
,
1140 struct rhash_head
*obj_old
, struct rhash_head
*obj_new
,
1141 const struct rhashtable_params params
)
1143 struct rhash_lock_head __rcu
**bkt
;
1144 struct rhash_head __rcu
**pprev
;
1145 struct rhash_head
*he
;
1149 /* Minimally, the old and new objects must have same hash
1150 * (which should mean identifiers are the same).
1152 hash
= rht_head_hashfn(ht
, tbl
, obj_old
, params
);
1153 if (hash
!= rht_head_hashfn(ht
, tbl
, obj_new
, params
))
1156 bkt
= rht_bucket_var(tbl
, hash
);
1163 rht_for_each_from(he
, rht_ptr(bkt
, tbl
, hash
), tbl
, hash
) {
1164 if (he
!= obj_old
) {
1169 rcu_assign_pointer(obj_new
->next
, obj_old
->next
);
1171 rcu_assign_pointer(*pprev
, obj_new
);
1172 rht_unlock(tbl
, bkt
);
1174 rht_assign_unlock(tbl
, bkt
, obj_new
);
1180 rht_unlock(tbl
, bkt
);
1187 * rhashtable_replace_fast - replace an object in hash table
1189 * @obj_old: pointer to hash head inside object being replaced
1190 * @obj_new: pointer to hash head inside object which is new
1191 * @params: hash table parameters
1193 * Replacing an object doesn't affect the number of elements in the hash table
1194 * or bucket, so we don't need to worry about shrinking or expanding the
1197 * Returns zero on success, -ENOENT if the entry could not be found,
1198 * -EINVAL if hash is not the same for the old and new objects.
1200 static inline int rhashtable_replace_fast(
1201 struct rhashtable
*ht
, struct rhash_head
*obj_old
,
1202 struct rhash_head
*obj_new
,
1203 const struct rhashtable_params params
)
1205 struct bucket_table
*tbl
;
1210 tbl
= rht_dereference_rcu(ht
->tbl
, ht
);
1212 /* Because we have already taken (and released) the bucket
1213 * lock in old_tbl, if we find that future_tbl is not yet
1214 * visible then that guarantees the entry to still be in
1215 * the old tbl if it exists.
1217 while ((err
= __rhashtable_replace_fast(ht
, tbl
, obj_old
,
1218 obj_new
, params
)) &&
1219 (tbl
= rht_dereference_rcu(tbl
->future_tbl
, ht
)))
1228 * rhltable_walk_enter - Initialise an iterator
1229 * @hlt: Table to walk over
1230 * @iter: Hash table Iterator
1232 * This function prepares a hash table walk.
1234 * Note that if you restart a walk after rhashtable_walk_stop you
1235 * may see the same object twice. Also, you may miss objects if
1236 * there are removals in between rhashtable_walk_stop and the next
1237 * call to rhashtable_walk_start.
1239 * For a completely stable walk you should construct your own data
1240 * structure outside the hash table.
1242 * This function may be called from any process context, including
1243 * non-preemptable context, but cannot be called from softirq or
1246 * You must call rhashtable_walk_exit after this function returns.
1248 static inline void rhltable_walk_enter(struct rhltable
*hlt
,
1249 struct rhashtable_iter
*iter
)
1251 return rhashtable_walk_enter(&hlt
->ht
, iter
);
1255 * rhltable_free_and_destroy - free elements and destroy hash list table
1256 * @hlt: the hash list table to destroy
1257 * @free_fn: callback to release resources of element
1258 * @arg: pointer passed to free_fn
1260 * See documentation for rhashtable_free_and_destroy.
1262 static inline void rhltable_free_and_destroy(struct rhltable
*hlt
,
1263 void (*free_fn
)(void *ptr
,
1267 return rhashtable_free_and_destroy(&hlt
->ht
, free_fn
, arg
);
1270 static inline void rhltable_destroy(struct rhltable
*hlt
)
1272 return rhltable_free_and_destroy(hlt
, NULL
, NULL
);
1275 #endif /* _LINUX_RHASHTABLE_H */