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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 */
47struct 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 */
76struct 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
108static inline bool rht_is_a_nulls(const struct rhash_head *ptr)
109{
110 return ((unsigned long) ptr & 1);
111}
112
113static 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
119static inline unsigned int rht_bucket_index(const struct bucket_table *tbl,
120 unsigned int hash)
121{
122 return hash & (tbl->size - 1);
123}
124
125static __always_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, key_len, hash_rnd);
141 else
142 hash = jhash2(key, key_len / sizeof(u32), 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, key_len, hash_rnd);
150 }
151
152 return hash;
153}
154
155static __always_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, tbl->hash_rnd);
160
161 return rht_bucket_index(tbl, hash);
162}
163
164static __always_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, params.obj_hashfn(ptr, params.key_len ?:
172 ht->p.key_len,
173 tbl->hash_rnd)) :
174 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 */
182static 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(&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 */
195static 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(&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 */
208static inline bool rht_grow_above_100(const struct rhashtable *ht,
209 const struct bucket_table *tbl)
210{
211 return atomic_read(&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 */
220static inline bool rht_grow_above_max(const struct rhashtable *ht,
221 const struct bucket_table *tbl)
222{
223 return atomic_read(&ht->nelems) >= ht->max_elems;
224}
225
226#ifdef CONFIG_PROVE_LOCKING
227int lockdep_rht_mutex_is_held(struct rhashtable *ht);
228int lockdep_rht_bucket_is_held(const struct bucket_table *tbl, u32 hash);
229#else
230static inline int lockdep_rht_mutex_is_held(struct rhashtable *ht)
231{
232 return 1;
233}
234
235static 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
242void *rhashtable_insert_slow(struct rhashtable *ht, const void *key,
243 struct rhash_head *obj);
244
245void rhashtable_walk_enter(struct rhashtable *ht,
246 struct rhashtable_iter *iter);
247void rhashtable_walk_exit(struct rhashtable_iter *iter);
248int rhashtable_walk_start_check(struct rhashtable_iter *iter) __acquires_shared(RCU);
249
250static inline void rhashtable_walk_start(struct rhashtable_iter *iter)
251 __acquires_shared(RCU)
252{
253 (void)rhashtable_walk_start_check(iter);
254}
255
256void *rhashtable_walk_next(struct rhashtable_iter *iter);
257void *rhashtable_walk_peek(struct rhashtable_iter *iter);
258void rhashtable_walk_stop(struct rhashtable_iter *iter) __releases_shared(RCU);
259
260void rhashtable_free_and_destroy(struct rhashtable *ht,
261 void (*free_fn)(void *ptr, void *arg),
262 void *arg);
263void rhashtable_destroy(struct rhashtable *ht);
264
265struct rhash_lock_head __rcu **rht_bucket_nested(
266 const struct bucket_table *tbl, unsigned int hash);
267struct rhash_lock_head __rcu **__rht_bucket_nested(
268 const struct bucket_table *tbl, unsigned int hash);
269struct rhash_lock_head __rcu **rht_bucket_nested_insert(
270 struct rhashtable *ht, struct bucket_table *tbl, unsigned int hash);
271
272#define rht_dereference(p, ht) \
273 rcu_dereference_protected(p, lockdep_rht_mutex_is_held(ht))
274
275#define rht_dereference_rcu(p, ht) \
276 rcu_dereference_all_check(p, lockdep_rht_mutex_is_held(ht))
277
278#define rht_dereference_bucket(p, tbl, hash) \
279 rcu_dereference_protected(p, lockdep_rht_bucket_is_held(tbl, hash))
280
281#define rht_dereference_bucket_rcu(p, tbl, hash) \
282 rcu_dereference_all_check(p, lockdep_rht_bucket_is_held(tbl, hash))
283
284#define rht_entry(tpos, pos, member) \
285 ({ tpos = container_of(pos, typeof(*tpos), member); 1; })
286
287static inline struct rhash_lock_head __rcu *const *rht_bucket(
288 const struct bucket_table *tbl, unsigned int hash)
289{
290 return unlikely(tbl->nest) ? rht_bucket_nested(tbl, hash) :
291 &tbl->buckets[hash];
292}
293
294static inline struct rhash_lock_head __rcu **rht_bucket_var(
295 struct bucket_table *tbl, unsigned int hash)
296{
297 return unlikely(tbl->nest) ? __rht_bucket_nested(tbl, hash) :
298 &tbl->buckets[hash];
299}
300
301static inline struct rhash_lock_head __rcu **rht_bucket_insert(
302 struct rhashtable *ht, struct bucket_table *tbl, unsigned int hash)
303{
304 return unlikely(tbl->nest) ? rht_bucket_nested_insert(ht, tbl, hash) :
305 &tbl->buckets[hash];
306}
307
308/*
309 * We lock a bucket by setting BIT(0) in the pointer - this is always
310 * zero in real pointers. The NULLS mark is never stored in the bucket,
311 * rather we store NULL if the bucket is empty.
312 * bit_spin_locks do not handle contention well, but the whole point
313 * of the hashtable design is to achieve minimum per-bucket contention.
314 * A nested hash table might not have a bucket pointer. In that case
315 * we cannot get a lock. For remove and replace the bucket cannot be
316 * interesting and doesn't need locking.
317 * For insert we allocate the bucket if this is the last bucket_table,
318 * and then take the lock.
319 * Sometimes we unlock a bucket by writing a new pointer there. In that
320 * case we don't need to unlock, but we do need to reset state such as
321 * local_bh. For that we have rht_assign_unlock(). As rcu_assign_pointer()
322 * provides the same release semantics that bit_spin_unlock() provides,
323 * this is safe.
324 * When we write to a bucket without unlocking, we use rht_assign_locked().
325 */
326
327static inline unsigned long rht_lock(struct bucket_table *tbl,
328 struct rhash_lock_head __rcu **bkt)
329 __acquires(__bitlock(0, bkt))
330{
331 unsigned long flags;
332
333 local_irq_save(flags);
334 bit_spin_lock(0, (unsigned long *)bkt);
335 lock_map_acquire(&tbl->dep_map);
336 return flags;
337}
338
339static inline unsigned long rht_lock_nested(struct bucket_table *tbl,
340 struct rhash_lock_head __rcu **bucket,
341 unsigned int subclass)
342 __acquires(__bitlock(0, bucket))
343{
344 unsigned long flags;
345
346 local_irq_save(flags);
347 bit_spin_lock(0, (unsigned long *)bucket);
348 lock_acquire_exclusive(&tbl->dep_map, subclass, 0, NULL, _THIS_IP_);
349 return flags;
350}
351
352static inline void rht_unlock(struct bucket_table *tbl,
353 struct rhash_lock_head __rcu **bkt,
354 unsigned long flags)
355 __releases(__bitlock(0, bkt))
356{
357 lock_map_release(&tbl->dep_map);
358 bit_spin_unlock(0, (unsigned long *)bkt);
359 local_irq_restore(flags);
360}
361
362enum rht_lookup_freq {
363 RHT_LOOKUP_NORMAL,
364 RHT_LOOKUP_LIKELY,
365};
366
367static __always_inline struct rhash_head *__rht_ptr(
368 struct rhash_lock_head *p, struct rhash_lock_head __rcu *const *bkt,
369 const enum rht_lookup_freq freq)
370{
371 unsigned long p_val = (unsigned long)p & ~BIT(0);
372
373 BUILD_BUG_ON(!__builtin_constant_p(freq));
374
375 if (freq == RHT_LOOKUP_LIKELY)
376 return (struct rhash_head *)
377 (likely(p_val) ? p_val : (unsigned long)RHT_NULLS_MARKER(bkt));
378 else
379 return (struct rhash_head *)
380 (p_val ?: (unsigned long)RHT_NULLS_MARKER(bkt));
381}
382
383/*
384 * Where 'bkt' is a bucket and might be locked:
385 * rht_ptr_rcu() dereferences that pointer and clears the lock bit.
386 * rht_ptr() dereferences in a context where the bucket is locked.
387 * rht_ptr_exclusive() dereferences in a context where exclusive
388 * access is guaranteed, such as when destroying the table.
389 */
390static __always_inline struct rhash_head *__rht_ptr_rcu(
391 struct rhash_lock_head __rcu *const *bkt,
392 const enum rht_lookup_freq freq)
393{
394 return __rht_ptr(rcu_dereference_all(*bkt), bkt, freq);
395}
396
397static inline struct rhash_head *rht_ptr_rcu(
398 struct rhash_lock_head __rcu *const *bkt)
399{
400 return __rht_ptr_rcu(bkt, RHT_LOOKUP_NORMAL);
401}
402
403static inline struct rhash_head *rht_ptr(
404 struct rhash_lock_head __rcu *const *bkt,
405 struct bucket_table *tbl,
406 unsigned int hash)
407{
408 return __rht_ptr(rht_dereference_bucket(*bkt, tbl, hash), bkt,
409 RHT_LOOKUP_NORMAL);
410}
411
412static inline struct rhash_head *rht_ptr_exclusive(
413 struct rhash_lock_head __rcu *const *bkt)
414{
415 return __rht_ptr(rcu_dereference_protected(*bkt, 1), bkt,
416 RHT_LOOKUP_NORMAL);
417}
418
419static inline void rht_assign_locked(struct rhash_lock_head __rcu **bkt,
420 struct rhash_head *obj)
421{
422 if (rht_is_a_nulls(obj))
423 obj = NULL;
424 rcu_assign_pointer(*bkt, (void *)((unsigned long)obj | BIT(0)));
425}
426
427static inline void rht_assign_unlock(struct bucket_table *tbl,
428 struct rhash_lock_head __rcu **bkt,
429 struct rhash_head *obj,
430 unsigned long flags)
431 __releases(__bitlock(0, bkt))
432{
433 if (rht_is_a_nulls(obj))
434 obj = NULL;
435 lock_map_release(&tbl->dep_map);
436 rcu_assign_pointer(*bkt, (void *)obj);
437 preempt_enable();
438 __release(__bitlock(0, bkt));
439 local_irq_restore(flags);
440}
441
442/**
443 * rht_for_each_from - iterate over hash chain from given head
444 * @pos: the &struct rhash_head to use as a loop cursor.
445 * @head: the &struct rhash_head to start from
446 * @tbl: the &struct bucket_table
447 * @hash: the hash value / bucket index
448 */
449#define rht_for_each_from(pos, head, tbl, hash) \
450 for (pos = head; \
451 !rht_is_a_nulls(pos); \
452 pos = rht_dereference_bucket((pos)->next, tbl, hash))
453
454/**
455 * rht_for_each - iterate over hash chain
456 * @pos: the &struct rhash_head to use as a loop cursor.
457 * @tbl: the &struct bucket_table
458 * @hash: the hash value / bucket index
459 */
460#define rht_for_each(pos, tbl, hash) \
461 rht_for_each_from(pos, rht_ptr(rht_bucket(tbl, hash), tbl, hash), \
462 tbl, hash)
463
464/**
465 * rht_for_each_entry_from - iterate over hash chain from given head
466 * @tpos: the type * to use as a loop cursor.
467 * @pos: the &struct rhash_head to use as a loop cursor.
468 * @head: the &struct rhash_head to start from
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#define rht_for_each_entry_from(tpos, pos, head, tbl, hash, member) \
474 for (pos = head; \
475 (!rht_is_a_nulls(pos)) && rht_entry(tpos, pos, member); \
476 pos = rht_dereference_bucket((pos)->next, tbl, hash))
477
478/**
479 * rht_for_each_entry - iterate over hash chain of given type
480 * @tpos: the type * to use as a loop cursor.
481 * @pos: the &struct rhash_head to use as a loop cursor.
482 * @tbl: the &struct bucket_table
483 * @hash: the hash value / bucket index
484 * @member: name of the &struct rhash_head within the hashable struct.
485 */
486#define rht_for_each_entry(tpos, pos, tbl, hash, member) \
487 rht_for_each_entry_from(tpos, pos, \
488 rht_ptr(rht_bucket(tbl, hash), tbl, hash), \
489 tbl, hash, member)
490
491/**
492 * rht_for_each_entry_safe - safely iterate over hash chain of given type
493 * @tpos: the type * to use as a loop cursor.
494 * @pos: the &struct rhash_head to use as a loop cursor.
495 * @next: the &struct rhash_head to use as next in loop cursor.
496 * @tbl: the &struct bucket_table
497 * @hash: the hash value / bucket index
498 * @member: name of the &struct rhash_head within the hashable struct.
499 *
500 * This hash chain list-traversal primitive allows for the looped code to
501 * remove the loop cursor from the list.
502 */
503#define rht_for_each_entry_safe(tpos, pos, next, tbl, hash, member) \
504 for (pos = rht_ptr(rht_bucket(tbl, hash), tbl, hash), \
505 next = !rht_is_a_nulls(pos) ? \
506 rht_dereference_bucket(pos->next, tbl, hash) : NULL; \
507 (!rht_is_a_nulls(pos)) && rht_entry(tpos, pos, member); \
508 pos = next, \
509 next = !rht_is_a_nulls(pos) ? \
510 rht_dereference_bucket(pos->next, tbl, hash) : NULL)
511
512/**
513 * rht_for_each_rcu_from - iterate over rcu hash chain from given head
514 * @pos: the &struct rhash_head to use as a loop cursor.
515 * @head: the &struct rhash_head to start from
516 * @tbl: the &struct bucket_table
517 * @hash: the hash value / bucket index
518 *
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().
522 */
523#define rht_for_each_rcu_from(pos, head, tbl, hash) \
524 for (({barrier(); }), \
525 pos = head; \
526 !rht_is_a_nulls(pos); \
527 pos = rcu_dereference_all(pos->next))
528
529/**
530 * rht_for_each_rcu - iterate over rcu hash chain
531 * @pos: the &struct rhash_head to use as a loop cursor.
532 * @tbl: the &struct bucket_table
533 * @hash: the hash value / bucket index
534 *
535 * This hash chain list-traversal primitive may safely run concurrently with
536 * the _rcu mutation primitives such as rhashtable_insert() as long as the
537 * traversal is guarded by rcu_read_lock().
538 */
539#define rht_for_each_rcu(pos, tbl, hash) \
540 for (({barrier(); }), \
541 pos = rht_ptr_rcu(rht_bucket(tbl, hash)); \
542 !rht_is_a_nulls(pos); \
543 pos = rcu_dereference_all(pos->next))
544
545/**
546 * rht_for_each_entry_rcu_from - iterated over rcu hash chain from given head
547 * @tpos: the type * to use as a loop cursor.
548 * @pos: the &struct rhash_head to use as a loop cursor.
549 * @head: the &struct rhash_head to start from
550 * @tbl: the &struct bucket_table
551 * @hash: the hash value / bucket index
552 * @member: name of the &struct rhash_head within the hashable struct.
553 *
554 * This hash chain list-traversal primitive may safely run concurrently with
555 * the _rcu mutation primitives such as rhashtable_insert() as long as the
556 * traversal is guarded by rcu_read_lock().
557 */
558#define rht_for_each_entry_rcu_from(tpos, pos, head, tbl, hash, member) \
559 for (({barrier(); }), \
560 pos = head; \
561 (!rht_is_a_nulls(pos)) && rht_entry(tpos, pos, member); \
562 pos = rht_dereference_bucket_rcu(pos->next, tbl, hash))
563
564/**
565 * rht_for_each_entry_rcu - iterate over rcu hash chain of given type
566 * @tpos: the type * to use as a loop cursor.
567 * @pos: the &struct rhash_head to use as a loop cursor.
568 * @tbl: the &struct bucket_table
569 * @hash: the hash value / bucket index
570 * @member: name of the &struct rhash_head within the hashable struct.
571 *
572 * This hash chain list-traversal primitive may safely run concurrently with
573 * the _rcu mutation primitives such as rhashtable_insert() as long as the
574 * traversal is guarded by rcu_read_lock().
575 */
576#define rht_for_each_entry_rcu(tpos, pos, tbl, hash, member) \
577 rht_for_each_entry_rcu_from(tpos, pos, \
578 rht_ptr_rcu(rht_bucket(tbl, hash)), \
579 tbl, hash, member)
580
581/**
582 * rhl_for_each_rcu - iterate over rcu hash table list
583 * @pos: the &struct rlist_head to use as a loop cursor.
584 * @list: the head of the list
585 *
586 * This hash chain list-traversal primitive should be used on the
587 * list returned by rhltable_lookup.
588 */
589#define rhl_for_each_rcu(pos, list) \
590 for (pos = list; pos; pos = rcu_dereference_all(pos->next))
591
592/**
593 * rhl_for_each_entry_rcu - iterate over rcu hash table list of given type
594 * @tpos: the type * to use as a loop cursor.
595 * @pos: the &struct rlist_head to use as a loop cursor.
596 * @list: the head of the list
597 * @member: name of the &struct rlist_head within the hashable struct.
598 *
599 * This hash chain list-traversal primitive should be used on the
600 * list returned by rhltable_lookup.
601 */
602#define rhl_for_each_entry_rcu(tpos, pos, list, member) \
603 for (pos = list; pos && rht_entry(tpos, pos, member); \
604 pos = rcu_dereference_all(pos->next))
605
606static inline int rhashtable_compare(struct rhashtable_compare_arg *arg,
607 const void *obj)
608{
609 struct rhashtable *ht = arg->ht;
610 const char *ptr = obj;
611
612 return memcmp(ptr + ht->p.key_offset, arg->key, ht->p.key_len);
613}
614
615/* Internal function, do not use. */
616static __always_inline struct rhash_head *__rhashtable_lookup(
617 struct rhashtable *ht, const void *key,
618 const struct rhashtable_params params,
619 const enum rht_lookup_freq freq)
620 __must_hold_shared(RCU)
621{
622 struct rhashtable_compare_arg arg = {
623 .ht = ht,
624 .key = key,
625 };
626 struct rhash_lock_head __rcu *const *bkt;
627 struct bucket_table *tbl;
628 struct rhash_head *he;
629 unsigned int hash;
630
631 BUILD_BUG_ON(!__builtin_constant_p(freq));
632 tbl = rht_dereference_rcu(ht->tbl, ht);
633restart:
634 hash = rht_key_hashfn(ht, tbl, key, params);
635 bkt = rht_bucket(tbl, hash);
636 do {
637 rht_for_each_rcu_from(he, __rht_ptr_rcu(bkt, freq), tbl, hash) {
638 if (params.obj_cmpfn ?
639 params.obj_cmpfn(&arg, rht_obj(ht, he)) :
640 rhashtable_compare(&arg, rht_obj(ht, he)))
641 continue;
642 return he;
643 }
644 /* An object might have been moved to a different hash chain,
645 * while we walk along it - better check and retry.
646 */
647 } while (he != RHT_NULLS_MARKER(bkt));
648
649 /* Ensure we see any new tables. */
650 smp_rmb();
651
652 tbl = rht_dereference_rcu(tbl->future_tbl, ht);
653 if (unlikely(tbl))
654 goto restart;
655
656 return NULL;
657}
658
659/**
660 * rhashtable_lookup - search hash table
661 * @ht: hash table
662 * @key: the pointer to the key
663 * @params: hash table parameters
664 *
665 * Computes the hash value for the key and traverses the bucket chain looking
666 * for an entry with an identical key. The first matching entry is returned.
667 *
668 * This must only be called under the RCU read lock.
669 *
670 * Returns the first entry on which the compare function returned true.
671 */
672static __always_inline void *rhashtable_lookup(
673 struct rhashtable *ht, const void *key,
674 const struct rhashtable_params params)
675 __must_hold_shared(RCU)
676{
677 struct rhash_head *he = __rhashtable_lookup(ht, key, params,
678 RHT_LOOKUP_NORMAL);
679
680 return he ? rht_obj(ht, he) : NULL;
681}
682
683static __always_inline void *rhashtable_lookup_likely(
684 struct rhashtable *ht, const void *key,
685 const struct rhashtable_params params)
686 __must_hold_shared(RCU)
687{
688 struct rhash_head *he = __rhashtable_lookup(ht, key, params,
689 RHT_LOOKUP_LIKELY);
690
691 return likely(he) ? rht_obj(ht, he) : NULL;
692}
693
694/**
695 * rhashtable_lookup_fast - search hash table, without RCU read lock
696 * @ht: hash table
697 * @key: the pointer to the key
698 * @params: hash table parameters
699 *
700 * Computes the hash value for the key and traverses the bucket chain looking
701 * for an entry with an identical key. The first matching entry is returned.
702 *
703 * Only use this function when you have other mechanisms guaranteeing
704 * that the object won't go away after the RCU read lock is released.
705 *
706 * Returns the first entry on which the compare function returned true.
707 */
708static __always_inline void *rhashtable_lookup_fast(
709 struct rhashtable *ht, const void *key,
710 const struct rhashtable_params params)
711{
712 void *obj;
713
714 rcu_read_lock();
715 obj = rhashtable_lookup(ht, key, params);
716 rcu_read_unlock();
717
718 return obj;
719}
720
721/**
722 * rhltable_lookup - search hash list table
723 * @hlt: hash table
724 * @key: the pointer to the key
725 * @params: hash table parameters
726 *
727 * Computes the hash value for the key and traverses the bucket chain looking
728 * for an entry with an identical key. All matching entries are returned
729 * in a list.
730 *
731 * This must only be called under the RCU read lock.
732 *
733 * Returns the list of entries that match the given key.
734 */
735static __always_inline struct rhlist_head *rhltable_lookup(
736 struct rhltable *hlt, const void *key,
737 const struct rhashtable_params params)
738 __must_hold_shared(RCU)
739{
740 struct rhash_head *he = __rhashtable_lookup(&hlt->ht, key, params,
741 RHT_LOOKUP_NORMAL);
742
743 return he ? container_of(he, struct rhlist_head, rhead) : NULL;
744}
745
746static __always_inline struct rhlist_head *rhltable_lookup_likely(
747 struct rhltable *hlt, const void *key,
748 const struct rhashtable_params params)
749 __must_hold_shared(RCU)
750{
751 struct rhash_head *he = __rhashtable_lookup(&hlt->ht, key, params,
752 RHT_LOOKUP_LIKELY);
753
754 return likely(he) ? container_of(he, struct rhlist_head, rhead) : NULL;
755}
756
757/* Internal function, please use rhashtable_insert_fast() instead. This
758 * function returns the existing element already in hashes if there is a clash,
759 * otherwise it returns an error via ERR_PTR().
760 */
761static __always_inline void *__rhashtable_insert_fast(
762 struct rhashtable *ht, const void *key, struct rhash_head *obj,
763 const struct rhashtable_params params, bool rhlist)
764{
765 struct rhashtable_compare_arg arg = {
766 .ht = ht,
767 .key = key,
768 };
769 struct rhash_lock_head __rcu **bkt;
770 struct rhash_head __rcu **pprev;
771 struct bucket_table *tbl;
772 struct rhash_head *head;
773 unsigned long flags;
774 unsigned int hash;
775 int elasticity;
776 void *data;
777
778 rcu_read_lock();
779
780 tbl = rht_dereference_rcu(ht->tbl, ht);
781 hash = rht_head_hashfn(ht, tbl, obj, params);
782 elasticity = RHT_ELASTICITY;
783 bkt = rht_bucket_insert(ht, tbl, hash);
784 data = ERR_PTR(-ENOMEM);
785 if (!bkt)
786 goto out;
787 pprev = NULL;
788 flags = rht_lock(tbl, bkt);
789
790 if (unlikely(rcu_access_pointer(tbl->future_tbl))) {
791slow_path:
792 rht_unlock(tbl, bkt, flags);
793 rcu_read_unlock();
794 return rhashtable_insert_slow(ht, key, obj);
795 }
796
797 rht_for_each_from(head, rht_ptr(bkt, tbl, hash), tbl, hash) {
798 struct rhlist_head *plist;
799 struct rhlist_head *list;
800
801 elasticity--;
802 if (!key ||
803 (params.obj_cmpfn ?
804 params.obj_cmpfn(&arg, rht_obj(ht, head)) :
805 rhashtable_compare(&arg, rht_obj(ht, head)))) {
806 pprev = &head->next;
807 continue;
808 }
809
810 data = rht_obj(ht, head);
811
812 if (!rhlist)
813 goto out_unlock;
814
815
816 list = container_of(obj, struct rhlist_head, rhead);
817 plist = container_of(head, struct rhlist_head, rhead);
818
819 RCU_INIT_POINTER(list->next, plist);
820 head = rht_dereference_bucket(head->next, tbl, hash);
821 RCU_INIT_POINTER(list->rhead.next, head);
822 if (pprev) {
823 rcu_assign_pointer(*pprev, obj);
824 rht_unlock(tbl, bkt, flags);
825 } else
826 rht_assign_unlock(tbl, bkt, obj, flags);
827 data = NULL;
828 goto out;
829 }
830
831 if (elasticity <= 0)
832 goto slow_path;
833
834 data = ERR_PTR(-E2BIG);
835 if (unlikely(rht_grow_above_max(ht, tbl)))
836 goto out_unlock;
837
838 if (unlikely(rht_grow_above_100(ht, tbl)))
839 goto slow_path;
840
841 /* Inserting at head of list makes unlocking free. */
842 head = rht_ptr(bkt, tbl, hash);
843
844 RCU_INIT_POINTER(obj->next, head);
845 if (rhlist) {
846 struct rhlist_head *list;
847
848 list = container_of(obj, struct rhlist_head, rhead);
849 RCU_INIT_POINTER(list->next, NULL);
850 }
851
852 atomic_inc(&ht->nelems);
853 rht_assign_unlock(tbl, bkt, obj, flags);
854
855 if (rht_grow_above_75(ht, tbl))
856 schedule_work(&ht->run_work);
857
858 data = NULL;
859out:
860 rcu_read_unlock();
861
862 return data;
863
864out_unlock:
865 rht_unlock(tbl, bkt, flags);
866 goto out;
867}
868
869/**
870 * rhashtable_insert_fast - insert object into hash table
871 * @ht: hash table
872 * @obj: pointer to hash head inside object
873 * @params: hash table parameters
874 *
875 * Will take the per bucket bitlock to protect against mutual mutations
876 * on the same bucket. Multiple insertions may occur in parallel unless
877 * they map to the same bucket.
878 *
879 * It is safe to call this function from atomic context.
880 *
881 * Will trigger an automatic deferred table resizing if residency in the
882 * table grows beyond 70%.
883 */
884static __always_inline int rhashtable_insert_fast(
885 struct rhashtable *ht, struct rhash_head *obj,
886 const struct rhashtable_params params)
887{
888 void *ret;
889
890 ret = __rhashtable_insert_fast(ht, NULL, obj, params, false);
891 if (IS_ERR(ret))
892 return PTR_ERR(ret);
893
894 return ret == NULL ? 0 : -EEXIST;
895}
896
897/**
898 * rhltable_insert_key - insert object into hash list table
899 * @hlt: hash list table
900 * @key: the pointer to the key
901 * @list: pointer to hash list head inside object
902 * @params: hash table parameters
903 *
904 * Will take the per bucket bitlock to protect against mutual mutations
905 * on the same bucket. Multiple insertions may occur in parallel unless
906 * they map to the same bucket.
907 *
908 * It is safe to call this function from atomic context.
909 *
910 * Will trigger an automatic deferred table resizing if residency in the
911 * table grows beyond 70%.
912 */
913static __always_inline int rhltable_insert_key(
914 struct rhltable *hlt, const void *key, struct rhlist_head *list,
915 const struct rhashtable_params params)
916{
917 return PTR_ERR(__rhashtable_insert_fast(&hlt->ht, key, &list->rhead,
918 params, true));
919}
920
921/**
922 * rhltable_insert - insert object into hash list table
923 * @hlt: hash list table
924 * @list: pointer to hash list head inside object
925 * @params: hash table parameters
926 *
927 * Will take the per bucket bitlock to protect against mutual mutations
928 * on the same bucket. Multiple insertions may occur in parallel unless
929 * they map to the same bucket.
930 *
931 * It is safe to call this function from atomic context.
932 *
933 * Will trigger an automatic deferred table resizing if residency in the
934 * table grows beyond 70%.
935 */
936static __always_inline int rhltable_insert(
937 struct rhltable *hlt, struct rhlist_head *list,
938 const struct rhashtable_params params)
939{
940 const char *key = rht_obj(&hlt->ht, &list->rhead);
941
942 key += params.key_offset;
943
944 return rhltable_insert_key(hlt, key, list, params);
945}
946
947/**
948 * rhashtable_lookup_insert_fast - lookup and insert object into hash table
949 * @ht: hash table
950 * @obj: pointer to hash head inside object
951 * @params: hash table parameters
952 *
953 * This lookup function may only be used for fixed key hash table (key_len
954 * parameter set). It will BUG() if used inappropriately.
955 *
956 * It is safe to call this function from atomic context.
957 *
958 * Will trigger an automatic deferred table resizing if residency in the
959 * table grows beyond 70%.
960 */
961static __always_inline int rhashtable_lookup_insert_fast(
962 struct rhashtable *ht, struct rhash_head *obj,
963 const struct rhashtable_params params)
964{
965 const char *key = rht_obj(ht, obj);
966 void *ret;
967
968 BUG_ON(ht->p.obj_hashfn);
969
970 ret = __rhashtable_insert_fast(ht, key + ht->p.key_offset, obj, params,
971 false);
972 if (IS_ERR(ret))
973 return PTR_ERR(ret);
974
975 return ret == NULL ? 0 : -EEXIST;
976}
977
978/**
979 * rhashtable_lookup_get_insert_fast - lookup and insert object into hash table
980 * @ht: hash table
981 * @obj: pointer to hash head inside object
982 * @params: hash table parameters
983 *
984 * Just like rhashtable_lookup_insert_fast(), but this function returns the
985 * object if it exists, NULL if it did not and the insertion was successful,
986 * and an ERR_PTR otherwise.
987 */
988static __always_inline void *rhashtable_lookup_get_insert_fast(
989 struct rhashtable *ht, struct rhash_head *obj,
990 const struct rhashtable_params params)
991{
992 const char *key = rht_obj(ht, obj);
993
994 BUG_ON(ht->p.obj_hashfn);
995
996 return __rhashtable_insert_fast(ht, key + ht->p.key_offset, obj, params,
997 false);
998}
999
1000/**
1001 * rhashtable_lookup_insert_key - search and insert object to hash table
1002 * with explicit key
1003 * @ht: hash table
1004 * @key: key
1005 * @obj: pointer to hash head inside object
1006 * @params: hash table parameters
1007 *
1008 * Lookups may occur in parallel with hashtable mutations and resizing.
1009 *
1010 * Will trigger an automatic deferred table resizing if residency in the
1011 * table grows beyond 70%.
1012 *
1013 * Returns zero on success.
1014 */
1015static __always_inline int rhashtable_lookup_insert_key(
1016 struct rhashtable *ht, const void *key, struct rhash_head *obj,
1017 const struct rhashtable_params params)
1018{
1019 void *ret;
1020
1021 BUG_ON(!ht->p.obj_hashfn || !key);
1022
1023 ret = __rhashtable_insert_fast(ht, key, obj, params, false);
1024 if (IS_ERR(ret))
1025 return PTR_ERR(ret);
1026
1027 return ret == NULL ? 0 : -EEXIST;
1028}
1029
1030/**
1031 * rhashtable_lookup_get_insert_key - lookup and insert object into hash table
1032 * @ht: hash table
1033 * @key: key
1034 * @obj: pointer to hash head inside object
1035 * @params: hash table parameters
1036 *
1037 * Just like rhashtable_lookup_insert_key(), but this function returns the
1038 * object if it exists, NULL if it does not and the insertion was successful,
1039 * and an ERR_PTR otherwise.
1040 */
1041static __always_inline void *rhashtable_lookup_get_insert_key(
1042 struct rhashtable *ht, const void *key, struct rhash_head *obj,
1043 const struct rhashtable_params params)
1044{
1045 BUG_ON(!ht->p.obj_hashfn || !key);
1046
1047 return __rhashtable_insert_fast(ht, key, obj, params, false);
1048}
1049
1050/* Internal function, please use rhashtable_remove_fast() instead */
1051static __always_inline int __rhashtable_remove_fast_one(
1052 struct rhashtable *ht, struct bucket_table *tbl,
1053 struct rhash_head *obj, const struct rhashtable_params params,
1054 bool rhlist)
1055{
1056 struct rhash_lock_head __rcu **bkt;
1057 struct rhash_head __rcu **pprev;
1058 struct rhash_head *he;
1059 unsigned long flags;
1060 unsigned int hash;
1061 int err = -ENOENT;
1062
1063 hash = rht_head_hashfn(ht, tbl, obj, params);
1064 bkt = rht_bucket_var(tbl, hash);
1065 if (!bkt)
1066 return -ENOENT;
1067 pprev = NULL;
1068 flags = rht_lock(tbl, bkt);
1069
1070 rht_for_each_from(he, rht_ptr(bkt, tbl, hash), tbl, hash) {
1071 struct rhlist_head *list;
1072
1073 list = container_of(he, struct rhlist_head, rhead);
1074
1075 if (he != obj) {
1076 struct rhlist_head __rcu **lpprev;
1077
1078 pprev = &he->next;
1079
1080 if (!rhlist)
1081 continue;
1082
1083 do {
1084 lpprev = &list->next;
1085 list = rht_dereference_bucket(list->next,
1086 tbl, hash);
1087 } while (list && obj != &list->rhead);
1088
1089 if (!list)
1090 continue;
1091
1092 list = rht_dereference_bucket(list->next, tbl, hash);
1093 RCU_INIT_POINTER(*lpprev, list);
1094 err = 0;
1095 break;
1096 }
1097
1098 obj = rht_dereference_bucket(obj->next, tbl, hash);
1099 err = 1;
1100
1101 if (rhlist) {
1102 list = rht_dereference_bucket(list->next, tbl, hash);
1103 if (list) {
1104 RCU_INIT_POINTER(list->rhead.next, obj);
1105 obj = &list->rhead;
1106 err = 0;
1107 }
1108 }
1109
1110 if (pprev) {
1111 rcu_assign_pointer(*pprev, obj);
1112 rht_unlock(tbl, bkt, flags);
1113 } else {
1114 rht_assign_unlock(tbl, bkt, obj, flags);
1115 }
1116 goto unlocked;
1117 }
1118
1119 rht_unlock(tbl, bkt, flags);
1120unlocked:
1121 if (err > 0) {
1122 atomic_dec(&ht->nelems);
1123 if (unlikely(ht->p.automatic_shrinking &&
1124 rht_shrink_below_30(ht, tbl)))
1125 schedule_work(&ht->run_work);
1126 err = 0;
1127 }
1128
1129 return err;
1130}
1131
1132/* Internal function, please use rhashtable_remove_fast() instead */
1133static __always_inline int __rhashtable_remove_fast(
1134 struct rhashtable *ht, struct rhash_head *obj,
1135 const struct rhashtable_params params, bool rhlist)
1136{
1137 struct bucket_table *tbl;
1138 int err;
1139
1140 rcu_read_lock();
1141
1142 tbl = rht_dereference_rcu(ht->tbl, ht);
1143
1144 /* Because we have already taken (and released) the bucket
1145 * lock in old_tbl, if we find that future_tbl is not yet
1146 * visible then that guarantees the entry to still be in
1147 * the old tbl if it exists.
1148 */
1149 while ((err = __rhashtable_remove_fast_one(ht, tbl, obj, params,
1150 rhlist)) &&
1151 (tbl = rht_dereference_rcu(tbl->future_tbl, ht)))
1152 ;
1153
1154 rcu_read_unlock();
1155
1156 return err;
1157}
1158
1159/**
1160 * rhashtable_remove_fast - remove object from hash table
1161 * @ht: hash table
1162 * @obj: pointer to hash head inside object
1163 * @params: hash table parameters
1164 *
1165 * Since the hash chain is single linked, the removal operation needs to
1166 * walk the bucket chain upon removal. The removal operation is thus
1167 * considerable slow if the hash table is not correctly sized.
1168 *
1169 * Will automatically shrink the table if permitted when residency drops
1170 * below 30%.
1171 *
1172 * Returns zero on success, -ENOENT if the entry could not be found.
1173 */
1174static __always_inline int rhashtable_remove_fast(
1175 struct rhashtable *ht, struct rhash_head *obj,
1176 const struct rhashtable_params params)
1177{
1178 return __rhashtable_remove_fast(ht, obj, params, false);
1179}
1180
1181/**
1182 * rhltable_remove - remove object from hash list table
1183 * @hlt: hash list table
1184 * @list: pointer to hash list head inside object
1185 * @params: hash table parameters
1186 *
1187 * Since the hash chain is single linked, the removal operation needs to
1188 * walk the bucket chain upon removal. The removal operation is thus
1189 * considerably slower if the hash table is not correctly sized.
1190 *
1191 * Will automatically shrink the table if permitted when residency drops
1192 * below 30%
1193 *
1194 * Returns zero on success, -ENOENT if the entry could not be found.
1195 */
1196static __always_inline int rhltable_remove(
1197 struct rhltable *hlt, struct rhlist_head *list,
1198 const struct rhashtable_params params)
1199{
1200 return __rhashtable_remove_fast(&hlt->ht, &list->rhead, params, true);
1201}
1202
1203/* Internal function, please use rhashtable_replace_fast() instead */
1204static __always_inline int __rhashtable_replace_fast(
1205 struct rhashtable *ht, struct bucket_table *tbl,
1206 struct rhash_head *obj_old, struct rhash_head *obj_new,
1207 const struct rhashtable_params params)
1208{
1209 struct rhash_lock_head __rcu **bkt;
1210 struct rhash_head __rcu **pprev;
1211 struct rhash_head *he;
1212 unsigned long flags;
1213 unsigned int hash;
1214 int err = -ENOENT;
1215
1216 /* Minimally, the old and new objects must have same hash
1217 * (which should mean identifiers are the same).
1218 */
1219 hash = rht_head_hashfn(ht, tbl, obj_old, params);
1220 if (hash != rht_head_hashfn(ht, tbl, obj_new, params))
1221 return -EINVAL;
1222
1223 bkt = rht_bucket_var(tbl, hash);
1224 if (!bkt)
1225 return -ENOENT;
1226
1227 pprev = NULL;
1228 flags = rht_lock(tbl, bkt);
1229
1230 rht_for_each_from(he, rht_ptr(bkt, tbl, hash), tbl, hash) {
1231 if (he != obj_old) {
1232 pprev = &he->next;
1233 continue;
1234 }
1235
1236 rcu_assign_pointer(obj_new->next, obj_old->next);
1237 if (pprev) {
1238 rcu_assign_pointer(*pprev, obj_new);
1239 rht_unlock(tbl, bkt, flags);
1240 } else {
1241 rht_assign_unlock(tbl, bkt, obj_new, flags);
1242 }
1243 err = 0;
1244 goto unlocked;
1245 }
1246
1247 rht_unlock(tbl, bkt, flags);
1248
1249unlocked:
1250 return err;
1251}
1252
1253/**
1254 * rhashtable_replace_fast - replace an object in hash table
1255 * @ht: hash table
1256 * @obj_old: pointer to hash head inside object being replaced
1257 * @obj_new: pointer to hash head inside object which is new
1258 * @params: hash table parameters
1259 *
1260 * Replacing an object doesn't affect the number of elements in the hash table
1261 * or bucket, so we don't need to worry about shrinking or expanding the
1262 * table here.
1263 *
1264 * Returns zero on success, -ENOENT if the entry could not be found,
1265 * -EINVAL if hash is not the same for the old and new objects.
1266 */
1267static __always_inline int rhashtable_replace_fast(
1268 struct rhashtable *ht, struct rhash_head *obj_old,
1269 struct rhash_head *obj_new,
1270 const struct rhashtable_params params)
1271{
1272 struct bucket_table *tbl;
1273 int err;
1274
1275 rcu_read_lock();
1276
1277 tbl = rht_dereference_rcu(ht->tbl, ht);
1278
1279 /* Because we have already taken (and released) the bucket
1280 * lock in old_tbl, if we find that future_tbl is not yet
1281 * visible then that guarantees the entry to still be in
1282 * the old tbl if it exists.
1283 */
1284 while ((err = __rhashtable_replace_fast(ht, tbl, obj_old,
1285 obj_new, params)) &&
1286 (tbl = rht_dereference_rcu(tbl->future_tbl, ht)))
1287 ;
1288
1289 rcu_read_unlock();
1290
1291 return err;
1292}
1293
1294/**
1295 * rhltable_walk_enter - Initialise an iterator
1296 * @hlt: Table to walk over
1297 * @iter: Hash table Iterator
1298 *
1299 * This function prepares a hash table walk.
1300 *
1301 * Note that if you restart a walk after rhashtable_walk_stop you
1302 * may see the same object twice. Also, you may miss objects if
1303 * there are removals in between rhashtable_walk_stop and the next
1304 * call to rhashtable_walk_start.
1305 *
1306 * For a completely stable walk you should construct your own data
1307 * structure outside the hash table.
1308 *
1309 * This function may be called from any process context, including
1310 * non-preemptable context, but cannot be called from softirq or
1311 * hardirq context.
1312 *
1313 * You must call rhashtable_walk_exit after this function returns.
1314 */
1315static inline void rhltable_walk_enter(struct rhltable *hlt,
1316 struct rhashtable_iter *iter)
1317{
1318 rhashtable_walk_enter(&hlt->ht, iter);
1319}
1320
1321/**
1322 * rhltable_free_and_destroy - free elements and destroy hash list table
1323 * @hlt: the hash list table to destroy
1324 * @free_fn: callback to release resources of element
1325 * @arg: pointer passed to free_fn
1326 *
1327 * See documentation for rhashtable_free_and_destroy.
1328 */
1329static inline void rhltable_free_and_destroy(struct rhltable *hlt,
1330 void (*free_fn)(void *ptr,
1331 void *arg),
1332 void *arg)
1333{
1334 rhashtable_free_and_destroy(&hlt->ht, free_fn, arg);
1335}
1336
1337static inline void rhltable_destroy(struct rhltable *hlt)
1338{
1339 rhltable_free_and_destroy(hlt, NULL, NULL);
1340}
1341
1342#endif /* _LINUX_RHASHTABLE_H */