787 lines · c
1// SPDX-License-Identifier: GPL-2.0-only2/*3 * Copyright (C) 2016 Facebook4 * Copyright (C) 2013-2014 Jens Axboe5 */6 7#include <linux/sched.h>8#include <linux/random.h>9#include <linux/sbitmap.h>10#include <linux/seq_file.h>11 12static int init_alloc_hint(struct sbitmap *sb, gfp_t flags)13{14 unsigned depth = sb->depth;15 16 sb->alloc_hint = alloc_percpu_gfp(unsigned int, flags);17 if (!sb->alloc_hint)18 return -ENOMEM;19 20 if (depth && !sb->round_robin) {21 int i;22 23 for_each_possible_cpu(i)24 *per_cpu_ptr(sb->alloc_hint, i) = get_random_u32_below(depth);25 }26 return 0;27}28 29static inline unsigned update_alloc_hint_before_get(struct sbitmap *sb,30 unsigned int depth)31{32 unsigned hint;33 34 hint = this_cpu_read(*sb->alloc_hint);35 if (unlikely(hint >= depth)) {36 hint = depth ? get_random_u32_below(depth) : 0;37 this_cpu_write(*sb->alloc_hint, hint);38 }39 40 return hint;41}42 43static inline void update_alloc_hint_after_get(struct sbitmap *sb,44 unsigned int depth,45 unsigned int hint,46 unsigned int nr)47{48 if (nr == -1) {49 /* If the map is full, a hint won't do us much good. */50 this_cpu_write(*sb->alloc_hint, 0);51 } else if (nr == hint || unlikely(sb->round_robin)) {52 /* Only update the hint if we used it. */53 hint = nr + 1;54 if (hint >= depth - 1)55 hint = 0;56 this_cpu_write(*sb->alloc_hint, hint);57 }58}59 60/*61 * See if we have deferred clears that we can batch move62 */63static inline bool sbitmap_deferred_clear(struct sbitmap_word *map,64 unsigned int depth, unsigned int alloc_hint, bool wrap)65{66 unsigned long mask, word_mask;67 68 guard(raw_spinlock_irqsave)(&map->swap_lock);69 70 if (!map->cleared) {71 if (depth == 0)72 return false;73 74 word_mask = (~0UL) >> (BITS_PER_LONG - depth);75 /*76 * The current behavior is to always retry after moving77 * ->cleared to word, and we change it to retry in case78 * of any free bits. To avoid an infinite loop, we need79 * to take wrap & alloc_hint into account, otherwise a80 * soft lockup may occur.81 */82 if (!wrap && alloc_hint)83 word_mask &= ~((1UL << alloc_hint) - 1);84 85 return (READ_ONCE(map->word) & word_mask) != word_mask;86 }87 88 /*89 * First get a stable cleared mask, setting the old mask to 0.90 */91 mask = xchg(&map->cleared, 0);92 93 /*94 * Now clear the masked bits in our free word95 */96 atomic_long_andnot(mask, (atomic_long_t *)&map->word);97 BUILD_BUG_ON(sizeof(atomic_long_t) != sizeof(map->word));98 return true;99}100 101int sbitmap_init_node(struct sbitmap *sb, unsigned int depth, int shift,102 gfp_t flags, int node, bool round_robin,103 bool alloc_hint)104{105 unsigned int bits_per_word;106 int i;107 108 if (shift < 0)109 shift = sbitmap_calculate_shift(depth);110 111 bits_per_word = 1U << shift;112 if (bits_per_word > BITS_PER_LONG)113 return -EINVAL;114 115 sb->shift = shift;116 sb->depth = depth;117 sb->map_nr = DIV_ROUND_UP(sb->depth, bits_per_word);118 sb->round_robin = round_robin;119 120 if (depth == 0) {121 sb->map = NULL;122 return 0;123 }124 125 if (alloc_hint) {126 if (init_alloc_hint(sb, flags))127 return -ENOMEM;128 } else {129 sb->alloc_hint = NULL;130 }131 132 sb->map = kvzalloc_node(sb->map_nr * sizeof(*sb->map), flags, node);133 if (!sb->map) {134 free_percpu(sb->alloc_hint);135 return -ENOMEM;136 }137 138 for (i = 0; i < sb->map_nr; i++)139 raw_spin_lock_init(&sb->map[i].swap_lock);140 141 return 0;142}143EXPORT_SYMBOL_GPL(sbitmap_init_node);144 145void sbitmap_resize(struct sbitmap *sb, unsigned int depth)146{147 unsigned int bits_per_word = 1U << sb->shift;148 unsigned int i;149 150 for (i = 0; i < sb->map_nr; i++)151 sbitmap_deferred_clear(&sb->map[i], 0, 0, 0);152 153 sb->depth = depth;154 sb->map_nr = DIV_ROUND_UP(sb->depth, bits_per_word);155}156EXPORT_SYMBOL_GPL(sbitmap_resize);157 158static int __sbitmap_get_word(unsigned long *word, unsigned long depth,159 unsigned int hint, bool wrap)160{161 int nr;162 163 /* don't wrap if starting from 0 */164 wrap = wrap && hint;165 166 while (1) {167 nr = find_next_zero_bit(word, depth, hint);168 if (unlikely(nr >= depth)) {169 /*170 * We started with an offset, and we didn't reset the171 * offset to 0 in a failure case, so start from 0 to172 * exhaust the map.173 */174 if (hint && wrap) {175 hint = 0;176 continue;177 }178 return -1;179 }180 181 if (!test_and_set_bit_lock(nr, word))182 break;183 184 hint = nr + 1;185 if (hint >= depth - 1)186 hint = 0;187 }188 189 return nr;190}191 192static int sbitmap_find_bit_in_word(struct sbitmap_word *map,193 unsigned int depth,194 unsigned int alloc_hint,195 bool wrap)196{197 int nr;198 199 do {200 nr = __sbitmap_get_word(&map->word, depth,201 alloc_hint, wrap);202 if (nr != -1)203 break;204 if (!sbitmap_deferred_clear(map, depth, alloc_hint, wrap))205 break;206 } while (1);207 208 return nr;209}210 211static int sbitmap_find_bit(struct sbitmap *sb,212 unsigned int depth,213 unsigned int index,214 unsigned int alloc_hint,215 bool wrap)216{217 unsigned int i;218 int nr = -1;219 220 for (i = 0; i < sb->map_nr; i++) {221 nr = sbitmap_find_bit_in_word(&sb->map[index],222 min_t(unsigned int,223 __map_depth(sb, index),224 depth),225 alloc_hint, wrap);226 227 if (nr != -1) {228 nr += index << sb->shift;229 break;230 }231 232 /* Jump to next index. */233 alloc_hint = 0;234 if (++index >= sb->map_nr)235 index = 0;236 }237 238 return nr;239}240 241static int __sbitmap_get(struct sbitmap *sb, unsigned int alloc_hint)242{243 unsigned int index;244 245 index = SB_NR_TO_INDEX(sb, alloc_hint);246 247 /*248 * Unless we're doing round robin tag allocation, just use the249 * alloc_hint to find the right word index. No point in looping250 * twice in find_next_zero_bit() for that case.251 */252 if (sb->round_robin)253 alloc_hint = SB_NR_TO_BIT(sb, alloc_hint);254 else255 alloc_hint = 0;256 257 return sbitmap_find_bit(sb, UINT_MAX, index, alloc_hint,258 !sb->round_robin);259}260 261int sbitmap_get(struct sbitmap *sb)262{263 int nr;264 unsigned int hint, depth;265 266 if (WARN_ON_ONCE(unlikely(!sb->alloc_hint)))267 return -1;268 269 depth = READ_ONCE(sb->depth);270 hint = update_alloc_hint_before_get(sb, depth);271 nr = __sbitmap_get(sb, hint);272 update_alloc_hint_after_get(sb, depth, hint, nr);273 274 return nr;275}276EXPORT_SYMBOL_GPL(sbitmap_get);277 278static int __sbitmap_get_shallow(struct sbitmap *sb,279 unsigned int alloc_hint,280 unsigned long shallow_depth)281{282 unsigned int index;283 284 index = SB_NR_TO_INDEX(sb, alloc_hint);285 alloc_hint = SB_NR_TO_BIT(sb, alloc_hint);286 287 return sbitmap_find_bit(sb, shallow_depth, index, alloc_hint, true);288}289 290int sbitmap_get_shallow(struct sbitmap *sb, unsigned long shallow_depth)291{292 int nr;293 unsigned int hint, depth;294 295 if (WARN_ON_ONCE(unlikely(!sb->alloc_hint)))296 return -1;297 298 depth = READ_ONCE(sb->depth);299 hint = update_alloc_hint_before_get(sb, depth);300 nr = __sbitmap_get_shallow(sb, hint, shallow_depth);301 update_alloc_hint_after_get(sb, depth, hint, nr);302 303 return nr;304}305EXPORT_SYMBOL_GPL(sbitmap_get_shallow);306 307bool sbitmap_any_bit_set(const struct sbitmap *sb)308{309 unsigned int i;310 311 for (i = 0; i < sb->map_nr; i++) {312 if (sb->map[i].word & ~sb->map[i].cleared)313 return true;314 }315 return false;316}317EXPORT_SYMBOL_GPL(sbitmap_any_bit_set);318 319static unsigned int __sbitmap_weight(const struct sbitmap *sb, bool set)320{321 unsigned int i, weight = 0;322 323 for (i = 0; i < sb->map_nr; i++) {324 const struct sbitmap_word *word = &sb->map[i];325 unsigned int word_depth = __map_depth(sb, i);326 327 if (set)328 weight += bitmap_weight(&word->word, word_depth);329 else330 weight += bitmap_weight(&word->cleared, word_depth);331 }332 return weight;333}334 335static unsigned int sbitmap_cleared(const struct sbitmap *sb)336{337 return __sbitmap_weight(sb, false);338}339 340unsigned int sbitmap_weight(const struct sbitmap *sb)341{342 return __sbitmap_weight(sb, true) - sbitmap_cleared(sb);343}344EXPORT_SYMBOL_GPL(sbitmap_weight);345 346void sbitmap_show(struct sbitmap *sb, struct seq_file *m)347{348 seq_printf(m, "depth=%u\n", sb->depth);349 seq_printf(m, "busy=%u\n", sbitmap_weight(sb));350 seq_printf(m, "cleared=%u\n", sbitmap_cleared(sb));351 seq_printf(m, "bits_per_word=%u\n", 1U << sb->shift);352 seq_printf(m, "map_nr=%u\n", sb->map_nr);353}354EXPORT_SYMBOL_GPL(sbitmap_show);355 356static inline void emit_byte(struct seq_file *m, unsigned int offset, u8 byte)357{358 if ((offset & 0xf) == 0) {359 if (offset != 0)360 seq_putc(m, '\n');361 seq_printf(m, "%08x:", offset);362 }363 if ((offset & 0x1) == 0)364 seq_putc(m, ' ');365 seq_printf(m, "%02x", byte);366}367 368void sbitmap_bitmap_show(struct sbitmap *sb, struct seq_file *m)369{370 u8 byte = 0;371 unsigned int byte_bits = 0;372 unsigned int offset = 0;373 int i;374 375 for (i = 0; i < sb->map_nr; i++) {376 unsigned long word = READ_ONCE(sb->map[i].word);377 unsigned long cleared = READ_ONCE(sb->map[i].cleared);378 unsigned int word_bits = __map_depth(sb, i);379 380 word &= ~cleared;381 382 while (word_bits > 0) {383 unsigned int bits = min(8 - byte_bits, word_bits);384 385 byte |= (word & (BIT(bits) - 1)) << byte_bits;386 byte_bits += bits;387 if (byte_bits == 8) {388 emit_byte(m, offset, byte);389 byte = 0;390 byte_bits = 0;391 offset++;392 }393 word >>= bits;394 word_bits -= bits;395 }396 }397 if (byte_bits) {398 emit_byte(m, offset, byte);399 offset++;400 }401 if (offset)402 seq_putc(m, '\n');403}404EXPORT_SYMBOL_GPL(sbitmap_bitmap_show);405 406static unsigned int sbq_calc_wake_batch(struct sbitmap_queue *sbq,407 unsigned int depth)408{409 unsigned int wake_batch;410 unsigned int shallow_depth;411 412 /*413 * Each full word of the bitmap has bits_per_word bits, and there might414 * be a partial word. There are depth / bits_per_word full words and415 * depth % bits_per_word bits left over. In bitwise arithmetic:416 *417 * bits_per_word = 1 << shift418 * depth / bits_per_word = depth >> shift419 * depth % bits_per_word = depth & ((1 << shift) - 1)420 *421 * Each word can be limited to sbq->min_shallow_depth bits.422 */423 shallow_depth = min(1U << sbq->sb.shift, sbq->min_shallow_depth);424 depth = ((depth >> sbq->sb.shift) * shallow_depth +425 min(depth & ((1U << sbq->sb.shift) - 1), shallow_depth));426 wake_batch = clamp_t(unsigned int, depth / SBQ_WAIT_QUEUES, 1,427 SBQ_WAKE_BATCH);428 429 return wake_batch;430}431 432int sbitmap_queue_init_node(struct sbitmap_queue *sbq, unsigned int depth,433 int shift, bool round_robin, gfp_t flags, int node)434{435 int ret;436 int i;437 438 ret = sbitmap_init_node(&sbq->sb, depth, shift, flags, node,439 round_robin, true);440 if (ret)441 return ret;442 443 sbq->min_shallow_depth = UINT_MAX;444 sbq->wake_batch = sbq_calc_wake_batch(sbq, depth);445 atomic_set(&sbq->wake_index, 0);446 atomic_set(&sbq->ws_active, 0);447 atomic_set(&sbq->completion_cnt, 0);448 atomic_set(&sbq->wakeup_cnt, 0);449 450 sbq->ws = kzalloc_node(SBQ_WAIT_QUEUES * sizeof(*sbq->ws), flags, node);451 if (!sbq->ws) {452 sbitmap_free(&sbq->sb);453 return -ENOMEM;454 }455 456 for (i = 0; i < SBQ_WAIT_QUEUES; i++)457 init_waitqueue_head(&sbq->ws[i].wait);458 459 return 0;460}461EXPORT_SYMBOL_GPL(sbitmap_queue_init_node);462 463static void sbitmap_queue_update_wake_batch(struct sbitmap_queue *sbq,464 unsigned int depth)465{466 unsigned int wake_batch;467 468 wake_batch = sbq_calc_wake_batch(sbq, depth);469 if (sbq->wake_batch != wake_batch)470 WRITE_ONCE(sbq->wake_batch, wake_batch);471}472 473void sbitmap_queue_recalculate_wake_batch(struct sbitmap_queue *sbq,474 unsigned int users)475{476 unsigned int wake_batch;477 unsigned int depth = (sbq->sb.depth + users - 1) / users;478 479 wake_batch = clamp_val(depth / SBQ_WAIT_QUEUES,480 1, SBQ_WAKE_BATCH);481 482 WRITE_ONCE(sbq->wake_batch, wake_batch);483}484EXPORT_SYMBOL_GPL(sbitmap_queue_recalculate_wake_batch);485 486void sbitmap_queue_resize(struct sbitmap_queue *sbq, unsigned int depth)487{488 sbitmap_queue_update_wake_batch(sbq, depth);489 sbitmap_resize(&sbq->sb, depth);490}491EXPORT_SYMBOL_GPL(sbitmap_queue_resize);492 493int __sbitmap_queue_get(struct sbitmap_queue *sbq)494{495 return sbitmap_get(&sbq->sb);496}497EXPORT_SYMBOL_GPL(__sbitmap_queue_get);498 499unsigned long __sbitmap_queue_get_batch(struct sbitmap_queue *sbq, int nr_tags,500 unsigned int *offset)501{502 struct sbitmap *sb = &sbq->sb;503 unsigned int hint, depth;504 unsigned long index, nr;505 int i;506 507 if (unlikely(sb->round_robin))508 return 0;509 510 depth = READ_ONCE(sb->depth);511 hint = update_alloc_hint_before_get(sb, depth);512 513 index = SB_NR_TO_INDEX(sb, hint);514 515 for (i = 0; i < sb->map_nr; i++) {516 struct sbitmap_word *map = &sb->map[index];517 unsigned long get_mask;518 unsigned int map_depth = __map_depth(sb, index);519 unsigned long val;520 521 sbitmap_deferred_clear(map, 0, 0, 0);522 val = READ_ONCE(map->word);523 if (val == (1UL << (map_depth - 1)) - 1)524 goto next;525 526 nr = find_first_zero_bit(&val, map_depth);527 if (nr + nr_tags <= map_depth) {528 atomic_long_t *ptr = (atomic_long_t *) &map->word;529 530 get_mask = ((1UL << nr_tags) - 1) << nr;531 while (!atomic_long_try_cmpxchg(ptr, &val,532 get_mask | val))533 ;534 get_mask = (get_mask & ~val) >> nr;535 if (get_mask) {536 *offset = nr + (index << sb->shift);537 update_alloc_hint_after_get(sb, depth, hint,538 *offset + nr_tags - 1);539 return get_mask;540 }541 }542next:543 /* Jump to next index. */544 if (++index >= sb->map_nr)545 index = 0;546 }547 548 return 0;549}550 551int sbitmap_queue_get_shallow(struct sbitmap_queue *sbq,552 unsigned int shallow_depth)553{554 WARN_ON_ONCE(shallow_depth < sbq->min_shallow_depth);555 556 return sbitmap_get_shallow(&sbq->sb, shallow_depth);557}558EXPORT_SYMBOL_GPL(sbitmap_queue_get_shallow);559 560void sbitmap_queue_min_shallow_depth(struct sbitmap_queue *sbq,561 unsigned int min_shallow_depth)562{563 sbq->min_shallow_depth = min_shallow_depth;564 sbitmap_queue_update_wake_batch(sbq, sbq->sb.depth);565}566EXPORT_SYMBOL_GPL(sbitmap_queue_min_shallow_depth);567 568static void __sbitmap_queue_wake_up(struct sbitmap_queue *sbq, int nr)569{570 int i, wake_index, woken;571 572 if (!atomic_read(&sbq->ws_active))573 return;574 575 wake_index = atomic_read(&sbq->wake_index);576 for (i = 0; i < SBQ_WAIT_QUEUES; i++) {577 struct sbq_wait_state *ws = &sbq->ws[wake_index];578 579 /*580 * Advance the index before checking the current queue.581 * It improves fairness, by ensuring the queue doesn't582 * need to be fully emptied before trying to wake up583 * from the next one.584 */585 wake_index = sbq_index_inc(wake_index);586 587 if (waitqueue_active(&ws->wait)) {588 woken = wake_up_nr(&ws->wait, nr);589 if (woken == nr)590 break;591 nr -= woken;592 }593 }594 595 if (wake_index != atomic_read(&sbq->wake_index))596 atomic_set(&sbq->wake_index, wake_index);597}598 599void sbitmap_queue_wake_up(struct sbitmap_queue *sbq, int nr)600{601 unsigned int wake_batch = READ_ONCE(sbq->wake_batch);602 unsigned int wakeups;603 604 if (!atomic_read(&sbq->ws_active))605 return;606 607 atomic_add(nr, &sbq->completion_cnt);608 wakeups = atomic_read(&sbq->wakeup_cnt);609 610 do {611 if (atomic_read(&sbq->completion_cnt) - wakeups < wake_batch)612 return;613 } while (!atomic_try_cmpxchg(&sbq->wakeup_cnt,614 &wakeups, wakeups + wake_batch));615 616 __sbitmap_queue_wake_up(sbq, wake_batch);617}618EXPORT_SYMBOL_GPL(sbitmap_queue_wake_up);619 620static inline void sbitmap_update_cpu_hint(struct sbitmap *sb, int cpu, int tag)621{622 if (likely(!sb->round_robin && tag < sb->depth))623 data_race(*per_cpu_ptr(sb->alloc_hint, cpu) = tag);624}625 626void sbitmap_queue_clear_batch(struct sbitmap_queue *sbq, int offset,627 int *tags, int nr_tags)628{629 struct sbitmap *sb = &sbq->sb;630 unsigned long *addr = NULL;631 unsigned long mask = 0;632 int i;633 634 smp_mb__before_atomic();635 for (i = 0; i < nr_tags; i++) {636 const int tag = tags[i] - offset;637 unsigned long *this_addr;638 639 /* since we're clearing a batch, skip the deferred map */640 this_addr = &sb->map[SB_NR_TO_INDEX(sb, tag)].word;641 if (!addr) {642 addr = this_addr;643 } else if (addr != this_addr) {644 atomic_long_andnot(mask, (atomic_long_t *) addr);645 mask = 0;646 addr = this_addr;647 }648 mask |= (1UL << SB_NR_TO_BIT(sb, tag));649 }650 651 if (mask)652 atomic_long_andnot(mask, (atomic_long_t *) addr);653 654 smp_mb__after_atomic();655 sbitmap_queue_wake_up(sbq, nr_tags);656 sbitmap_update_cpu_hint(&sbq->sb, raw_smp_processor_id(),657 tags[nr_tags - 1] - offset);658}659 660void sbitmap_queue_clear(struct sbitmap_queue *sbq, unsigned int nr,661 unsigned int cpu)662{663 /*664 * Once the clear bit is set, the bit may be allocated out.665 *666 * Orders READ/WRITE on the associated instance(such as request667 * of blk_mq) by this bit for avoiding race with re-allocation,668 * and its pair is the memory barrier implied in __sbitmap_get_word.669 *670 * One invariant is that the clear bit has to be zero when the bit671 * is in use.672 */673 smp_mb__before_atomic();674 sbitmap_deferred_clear_bit(&sbq->sb, nr);675 676 /*677 * Pairs with the memory barrier in set_current_state() to ensure the678 * proper ordering of clear_bit_unlock()/waitqueue_active() in the waker679 * and test_and_set_bit_lock()/prepare_to_wait()/finish_wait() in the680 * waiter. See the comment on waitqueue_active().681 */682 smp_mb__after_atomic();683 sbitmap_queue_wake_up(sbq, 1);684 sbitmap_update_cpu_hint(&sbq->sb, cpu, nr);685}686EXPORT_SYMBOL_GPL(sbitmap_queue_clear);687 688void sbitmap_queue_wake_all(struct sbitmap_queue *sbq)689{690 int i, wake_index;691 692 /*693 * Pairs with the memory barrier in set_current_state() like in694 * sbitmap_queue_wake_up().695 */696 smp_mb();697 wake_index = atomic_read(&sbq->wake_index);698 for (i = 0; i < SBQ_WAIT_QUEUES; i++) {699 struct sbq_wait_state *ws = &sbq->ws[wake_index];700 701 if (waitqueue_active(&ws->wait))702 wake_up(&ws->wait);703 704 wake_index = sbq_index_inc(wake_index);705 }706}707EXPORT_SYMBOL_GPL(sbitmap_queue_wake_all);708 709void sbitmap_queue_show(struct sbitmap_queue *sbq, struct seq_file *m)710{711 bool first;712 int i;713 714 sbitmap_show(&sbq->sb, m);715 716 seq_puts(m, "alloc_hint={");717 first = true;718 for_each_possible_cpu(i) {719 if (!first)720 seq_puts(m, ", ");721 first = false;722 seq_printf(m, "%u", *per_cpu_ptr(sbq->sb.alloc_hint, i));723 }724 seq_puts(m, "}\n");725 726 seq_printf(m, "wake_batch=%u\n", sbq->wake_batch);727 seq_printf(m, "wake_index=%d\n", atomic_read(&sbq->wake_index));728 seq_printf(m, "ws_active=%d\n", atomic_read(&sbq->ws_active));729 730 seq_puts(m, "ws={\n");731 for (i = 0; i < SBQ_WAIT_QUEUES; i++) {732 struct sbq_wait_state *ws = &sbq->ws[i];733 seq_printf(m, "\t{.wait=%s},\n",734 waitqueue_active(&ws->wait) ? "active" : "inactive");735 }736 seq_puts(m, "}\n");737 738 seq_printf(m, "round_robin=%d\n", sbq->sb.round_robin);739 seq_printf(m, "min_shallow_depth=%u\n", sbq->min_shallow_depth);740}741EXPORT_SYMBOL_GPL(sbitmap_queue_show);742 743void sbitmap_add_wait_queue(struct sbitmap_queue *sbq,744 struct sbq_wait_state *ws,745 struct sbq_wait *sbq_wait)746{747 if (!sbq_wait->sbq) {748 sbq_wait->sbq = sbq;749 atomic_inc(&sbq->ws_active);750 add_wait_queue(&ws->wait, &sbq_wait->wait);751 }752}753EXPORT_SYMBOL_GPL(sbitmap_add_wait_queue);754 755void sbitmap_del_wait_queue(struct sbq_wait *sbq_wait)756{757 list_del_init(&sbq_wait->wait.entry);758 if (sbq_wait->sbq) {759 atomic_dec(&sbq_wait->sbq->ws_active);760 sbq_wait->sbq = NULL;761 }762}763EXPORT_SYMBOL_GPL(sbitmap_del_wait_queue);764 765void sbitmap_prepare_to_wait(struct sbitmap_queue *sbq,766 struct sbq_wait_state *ws,767 struct sbq_wait *sbq_wait, int state)768{769 if (!sbq_wait->sbq) {770 atomic_inc(&sbq->ws_active);771 sbq_wait->sbq = sbq;772 }773 prepare_to_wait_exclusive(&ws->wait, &sbq_wait->wait, state);774}775EXPORT_SYMBOL_GPL(sbitmap_prepare_to_wait);776 777void sbitmap_finish_wait(struct sbitmap_queue *sbq, struct sbq_wait_state *ws,778 struct sbq_wait *sbq_wait)779{780 finish_wait(&ws->wait, &sbq_wait->wait);781 if (sbq_wait->sbq) {782 atomic_dec(&sbq->ws_active);783 sbq_wait->sbq = NULL;784 }785}786EXPORT_SYMBOL_GPL(sbitmap_finish_wait);787