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1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * Copyright (C) 2016 Facebook
4 * Copyright (C) 2013-2014 Jens Axboe
5 */
6
7#include <linux/sched.h>
8#include <linux/random.h>
9#include <linux/sbitmap.h>
10#include <linux/seq_file.h>
11
12/*
13 * See if we have deferred clears that we can batch move
14 */
15static inline bool sbitmap_deferred_clear(struct sbitmap *sb, int index)
16{
17 unsigned long mask, val;
18 bool ret = false;
19 unsigned long flags;
20
21 spin_lock_irqsave(&sb->map[index].swap_lock, flags);
22
23 if (!sb->map[index].cleared)
24 goto out_unlock;
25
26 /*
27 * First get a stable cleared mask, setting the old mask to 0.
28 */
29 mask = xchg(&sb->map[index].cleared, 0);
30
31 /*
32 * Now clear the masked bits in our free word
33 */
34 do {
35 val = sb->map[index].word;
36 } while (cmpxchg(&sb->map[index].word, val, val & ~mask) != val);
37
38 ret = true;
39out_unlock:
40 spin_unlock_irqrestore(&sb->map[index].swap_lock, flags);
41 return ret;
42}
43
44int sbitmap_init_node(struct sbitmap *sb, unsigned int depth, int shift,
45 gfp_t flags, int node)
46{
47 unsigned int bits_per_word;
48 unsigned int i;
49
50 if (shift < 0) {
51 shift = ilog2(BITS_PER_LONG);
52 /*
53 * If the bitmap is small, shrink the number of bits per word so
54 * we spread over a few cachelines, at least. If less than 4
55 * bits, just forget about it, it's not going to work optimally
56 * anyway.
57 */
58 if (depth >= 4) {
59 while ((4U << shift) > depth)
60 shift--;
61 }
62 }
63 bits_per_word = 1U << shift;
64 if (bits_per_word > BITS_PER_LONG)
65 return -EINVAL;
66
67 sb->shift = shift;
68 sb->depth = depth;
69 sb->map_nr = DIV_ROUND_UP(sb->depth, bits_per_word);
70
71 if (depth == 0) {
72 sb->map = NULL;
73 return 0;
74 }
75
76 sb->map = kcalloc_node(sb->map_nr, sizeof(*sb->map), flags, node);
77 if (!sb->map)
78 return -ENOMEM;
79
80 for (i = 0; i < sb->map_nr; i++) {
81 sb->map[i].depth = min(depth, bits_per_word);
82 depth -= sb->map[i].depth;
83 spin_lock_init(&sb->map[i].swap_lock);
84 }
85 return 0;
86}
87EXPORT_SYMBOL_GPL(sbitmap_init_node);
88
89void sbitmap_resize(struct sbitmap *sb, unsigned int depth)
90{
91 unsigned int bits_per_word = 1U << sb->shift;
92 unsigned int i;
93
94 for (i = 0; i < sb->map_nr; i++)
95 sbitmap_deferred_clear(sb, i);
96
97 sb->depth = depth;
98 sb->map_nr = DIV_ROUND_UP(sb->depth, bits_per_word);
99
100 for (i = 0; i < sb->map_nr; i++) {
101 sb->map[i].depth = min(depth, bits_per_word);
102 depth -= sb->map[i].depth;
103 }
104}
105EXPORT_SYMBOL_GPL(sbitmap_resize);
106
107static int __sbitmap_get_word(unsigned long *word, unsigned long depth,
108 unsigned int hint, bool wrap)
109{
110 unsigned int orig_hint = hint;
111 int nr;
112
113 while (1) {
114 nr = find_next_zero_bit(word, depth, hint);
115 if (unlikely(nr >= depth)) {
116 /*
117 * We started with an offset, and we didn't reset the
118 * offset to 0 in a failure case, so start from 0 to
119 * exhaust the map.
120 */
121 if (orig_hint && hint && wrap) {
122 hint = orig_hint = 0;
123 continue;
124 }
125 return -1;
126 }
127
128 if (!test_and_set_bit_lock(nr, word))
129 break;
130
131 hint = nr + 1;
132 if (hint >= depth - 1)
133 hint = 0;
134 }
135
136 return nr;
137}
138
139static int sbitmap_find_bit_in_index(struct sbitmap *sb, int index,
140 unsigned int alloc_hint, bool round_robin)
141{
142 int nr;
143
144 do {
145 nr = __sbitmap_get_word(&sb->map[index].word,
146 sb->map[index].depth, alloc_hint,
147 !round_robin);
148 if (nr != -1)
149 break;
150 if (!sbitmap_deferred_clear(sb, index))
151 break;
152 } while (1);
153
154 return nr;
155}
156
157int sbitmap_get(struct sbitmap *sb, unsigned int alloc_hint, bool round_robin)
158{
159 unsigned int i, index;
160 int nr = -1;
161
162 index = SB_NR_TO_INDEX(sb, alloc_hint);
163
164 /*
165 * Unless we're doing round robin tag allocation, just use the
166 * alloc_hint to find the right word index. No point in looping
167 * twice in find_next_zero_bit() for that case.
168 */
169 if (round_robin)
170 alloc_hint = SB_NR_TO_BIT(sb, alloc_hint);
171 else
172 alloc_hint = 0;
173
174 for (i = 0; i < sb->map_nr; i++) {
175 nr = sbitmap_find_bit_in_index(sb, index, alloc_hint,
176 round_robin);
177 if (nr != -1) {
178 nr += index << sb->shift;
179 break;
180 }
181
182 /* Jump to next index. */
183 alloc_hint = 0;
184 if (++index >= sb->map_nr)
185 index = 0;
186 }
187
188 return nr;
189}
190EXPORT_SYMBOL_GPL(sbitmap_get);
191
192int sbitmap_get_shallow(struct sbitmap *sb, unsigned int alloc_hint,
193 unsigned long shallow_depth)
194{
195 unsigned int i, index;
196 int nr = -1;
197
198 index = SB_NR_TO_INDEX(sb, alloc_hint);
199
200 for (i = 0; i < sb->map_nr; i++) {
201again:
202 nr = __sbitmap_get_word(&sb->map[index].word,
203 min(sb->map[index].depth, shallow_depth),
204 SB_NR_TO_BIT(sb, alloc_hint), true);
205 if (nr != -1) {
206 nr += index << sb->shift;
207 break;
208 }
209
210 if (sbitmap_deferred_clear(sb, index))
211 goto again;
212
213 /* Jump to next index. */
214 index++;
215 alloc_hint = index << sb->shift;
216
217 if (index >= sb->map_nr) {
218 index = 0;
219 alloc_hint = 0;
220 }
221 }
222
223 return nr;
224}
225EXPORT_SYMBOL_GPL(sbitmap_get_shallow);
226
227bool sbitmap_any_bit_set(const struct sbitmap *sb)
228{
229 unsigned int i;
230
231 for (i = 0; i < sb->map_nr; i++) {
232 if (sb->map[i].word & ~sb->map[i].cleared)
233 return true;
234 }
235 return false;
236}
237EXPORT_SYMBOL_GPL(sbitmap_any_bit_set);
238
239bool sbitmap_any_bit_clear(const struct sbitmap *sb)
240{
241 unsigned int i;
242
243 for (i = 0; i < sb->map_nr; i++) {
244 const struct sbitmap_word *word = &sb->map[i];
245 unsigned long mask = word->word & ~word->cleared;
246 unsigned long ret;
247
248 ret = find_first_zero_bit(&mask, word->depth);
249 if (ret < word->depth)
250 return true;
251 }
252 return false;
253}
254EXPORT_SYMBOL_GPL(sbitmap_any_bit_clear);
255
256static unsigned int __sbitmap_weight(const struct sbitmap *sb, bool set)
257{
258 unsigned int i, weight = 0;
259
260 for (i = 0; i < sb->map_nr; i++) {
261 const struct sbitmap_word *word = &sb->map[i];
262
263 if (set)
264 weight += bitmap_weight(&word->word, word->depth);
265 else
266 weight += bitmap_weight(&word->cleared, word->depth);
267 }
268 return weight;
269}
270
271static unsigned int sbitmap_weight(const struct sbitmap *sb)
272{
273 return __sbitmap_weight(sb, true);
274}
275
276static unsigned int sbitmap_cleared(const struct sbitmap *sb)
277{
278 return __sbitmap_weight(sb, false);
279}
280
281void sbitmap_show(struct sbitmap *sb, struct seq_file *m)
282{
283 seq_printf(m, "depth=%u\n", sb->depth);
284 seq_printf(m, "busy=%u\n", sbitmap_weight(sb) - sbitmap_cleared(sb));
285 seq_printf(m, "cleared=%u\n", sbitmap_cleared(sb));
286 seq_printf(m, "bits_per_word=%u\n", 1U << sb->shift);
287 seq_printf(m, "map_nr=%u\n", sb->map_nr);
288}
289EXPORT_SYMBOL_GPL(sbitmap_show);
290
291static inline void emit_byte(struct seq_file *m, unsigned int offset, u8 byte)
292{
293 if ((offset & 0xf) == 0) {
294 if (offset != 0)
295 seq_putc(m, '\n');
296 seq_printf(m, "%08x:", offset);
297 }
298 if ((offset & 0x1) == 0)
299 seq_putc(m, ' ');
300 seq_printf(m, "%02x", byte);
301}
302
303void sbitmap_bitmap_show(struct sbitmap *sb, struct seq_file *m)
304{
305 u8 byte = 0;
306 unsigned int byte_bits = 0;
307 unsigned int offset = 0;
308 int i;
309
310 for (i = 0; i < sb->map_nr; i++) {
311 unsigned long word = READ_ONCE(sb->map[i].word);
312 unsigned int word_bits = READ_ONCE(sb->map[i].depth);
313
314 while (word_bits > 0) {
315 unsigned int bits = min(8 - byte_bits, word_bits);
316
317 byte |= (word & (BIT(bits) - 1)) << byte_bits;
318 byte_bits += bits;
319 if (byte_bits == 8) {
320 emit_byte(m, offset, byte);
321 byte = 0;
322 byte_bits = 0;
323 offset++;
324 }
325 word >>= bits;
326 word_bits -= bits;
327 }
328 }
329 if (byte_bits) {
330 emit_byte(m, offset, byte);
331 offset++;
332 }
333 if (offset)
334 seq_putc(m, '\n');
335}
336EXPORT_SYMBOL_GPL(sbitmap_bitmap_show);
337
338static unsigned int sbq_calc_wake_batch(struct sbitmap_queue *sbq,
339 unsigned int depth)
340{
341 unsigned int wake_batch;
342 unsigned int shallow_depth;
343
344 /*
345 * For each batch, we wake up one queue. We need to make sure that our
346 * batch size is small enough that the full depth of the bitmap,
347 * potentially limited by a shallow depth, is enough to wake up all of
348 * the queues.
349 *
350 * Each full word of the bitmap has bits_per_word bits, and there might
351 * be a partial word. There are depth / bits_per_word full words and
352 * depth % bits_per_word bits left over. In bitwise arithmetic:
353 *
354 * bits_per_word = 1 << shift
355 * depth / bits_per_word = depth >> shift
356 * depth % bits_per_word = depth & ((1 << shift) - 1)
357 *
358 * Each word can be limited to sbq->min_shallow_depth bits.
359 */
360 shallow_depth = min(1U << sbq->sb.shift, sbq->min_shallow_depth);
361 depth = ((depth >> sbq->sb.shift) * shallow_depth +
362 min(depth & ((1U << sbq->sb.shift) - 1), shallow_depth));
363 wake_batch = clamp_t(unsigned int, depth / SBQ_WAIT_QUEUES, 1,
364 SBQ_WAKE_BATCH);
365
366 return wake_batch;
367}
368
369int sbitmap_queue_init_node(struct sbitmap_queue *sbq, unsigned int depth,
370 int shift, bool round_robin, gfp_t flags, int node)
371{
372 int ret;
373 int i;
374
375 ret = sbitmap_init_node(&sbq->sb, depth, shift, flags, node);
376 if (ret)
377 return ret;
378
379 sbq->alloc_hint = alloc_percpu_gfp(unsigned int, flags);
380 if (!sbq->alloc_hint) {
381 sbitmap_free(&sbq->sb);
382 return -ENOMEM;
383 }
384
385 if (depth && !round_robin) {
386 for_each_possible_cpu(i)
387 *per_cpu_ptr(sbq->alloc_hint, i) = prandom_u32() % depth;
388 }
389
390 sbq->min_shallow_depth = UINT_MAX;
391 sbq->wake_batch = sbq_calc_wake_batch(sbq, depth);
392 atomic_set(&sbq->wake_index, 0);
393 atomic_set(&sbq->ws_active, 0);
394
395 sbq->ws = kzalloc_node(SBQ_WAIT_QUEUES * sizeof(*sbq->ws), flags, node);
396 if (!sbq->ws) {
397 free_percpu(sbq->alloc_hint);
398 sbitmap_free(&sbq->sb);
399 return -ENOMEM;
400 }
401
402 for (i = 0; i < SBQ_WAIT_QUEUES; i++) {
403 init_waitqueue_head(&sbq->ws[i].wait);
404 atomic_set(&sbq->ws[i].wait_cnt, sbq->wake_batch);
405 }
406
407 sbq->round_robin = round_robin;
408 return 0;
409}
410EXPORT_SYMBOL_GPL(sbitmap_queue_init_node);
411
412static void sbitmap_queue_update_wake_batch(struct sbitmap_queue *sbq,
413 unsigned int depth)
414{
415 unsigned int wake_batch = sbq_calc_wake_batch(sbq, depth);
416 int i;
417
418 if (sbq->wake_batch != wake_batch) {
419 WRITE_ONCE(sbq->wake_batch, wake_batch);
420 /*
421 * Pairs with the memory barrier in sbitmap_queue_wake_up()
422 * to ensure that the batch size is updated before the wait
423 * counts.
424 */
425 smp_mb();
426 for (i = 0; i < SBQ_WAIT_QUEUES; i++)
427 atomic_set(&sbq->ws[i].wait_cnt, 1);
428 }
429}
430
431void sbitmap_queue_resize(struct sbitmap_queue *sbq, unsigned int depth)
432{
433 sbitmap_queue_update_wake_batch(sbq, depth);
434 sbitmap_resize(&sbq->sb, depth);
435}
436EXPORT_SYMBOL_GPL(sbitmap_queue_resize);
437
438int __sbitmap_queue_get(struct sbitmap_queue *sbq)
439{
440 unsigned int hint, depth;
441 int nr;
442
443 hint = this_cpu_read(*sbq->alloc_hint);
444 depth = READ_ONCE(sbq->sb.depth);
445 if (unlikely(hint >= depth)) {
446 hint = depth ? prandom_u32() % depth : 0;
447 this_cpu_write(*sbq->alloc_hint, hint);
448 }
449 nr = sbitmap_get(&sbq->sb, hint, sbq->round_robin);
450
451 if (nr == -1) {
452 /* If the map is full, a hint won't do us much good. */
453 this_cpu_write(*sbq->alloc_hint, 0);
454 } else if (nr == hint || unlikely(sbq->round_robin)) {
455 /* Only update the hint if we used it. */
456 hint = nr + 1;
457 if (hint >= depth - 1)
458 hint = 0;
459 this_cpu_write(*sbq->alloc_hint, hint);
460 }
461
462 return nr;
463}
464EXPORT_SYMBOL_GPL(__sbitmap_queue_get);
465
466int __sbitmap_queue_get_shallow(struct sbitmap_queue *sbq,
467 unsigned int shallow_depth)
468{
469 unsigned int hint, depth;
470 int nr;
471
472 WARN_ON_ONCE(shallow_depth < sbq->min_shallow_depth);
473
474 hint = this_cpu_read(*sbq->alloc_hint);
475 depth = READ_ONCE(sbq->sb.depth);
476 if (unlikely(hint >= depth)) {
477 hint = depth ? prandom_u32() % depth : 0;
478 this_cpu_write(*sbq->alloc_hint, hint);
479 }
480 nr = sbitmap_get_shallow(&sbq->sb, hint, shallow_depth);
481
482 if (nr == -1) {
483 /* If the map is full, a hint won't do us much good. */
484 this_cpu_write(*sbq->alloc_hint, 0);
485 } else if (nr == hint || unlikely(sbq->round_robin)) {
486 /* Only update the hint if we used it. */
487 hint = nr + 1;
488 if (hint >= depth - 1)
489 hint = 0;
490 this_cpu_write(*sbq->alloc_hint, hint);
491 }
492
493 return nr;
494}
495EXPORT_SYMBOL_GPL(__sbitmap_queue_get_shallow);
496
497void sbitmap_queue_min_shallow_depth(struct sbitmap_queue *sbq,
498 unsigned int min_shallow_depth)
499{
500 sbq->min_shallow_depth = min_shallow_depth;
501 sbitmap_queue_update_wake_batch(sbq, sbq->sb.depth);
502}
503EXPORT_SYMBOL_GPL(sbitmap_queue_min_shallow_depth);
504
505static struct sbq_wait_state *sbq_wake_ptr(struct sbitmap_queue *sbq)
506{
507 int i, wake_index;
508
509 if (!atomic_read(&sbq->ws_active))
510 return NULL;
511
512 wake_index = atomic_read(&sbq->wake_index);
513 for (i = 0; i < SBQ_WAIT_QUEUES; i++) {
514 struct sbq_wait_state *ws = &sbq->ws[wake_index];
515
516 if (waitqueue_active(&ws->wait)) {
517 if (wake_index != atomic_read(&sbq->wake_index))
518 atomic_set(&sbq->wake_index, wake_index);
519 return ws;
520 }
521
522 wake_index = sbq_index_inc(wake_index);
523 }
524
525 return NULL;
526}
527
528static bool __sbq_wake_up(struct sbitmap_queue *sbq)
529{
530 struct sbq_wait_state *ws;
531 unsigned int wake_batch;
532 int wait_cnt;
533
534 ws = sbq_wake_ptr(sbq);
535 if (!ws)
536 return false;
537
538 wait_cnt = atomic_dec_return(&ws->wait_cnt);
539 if (wait_cnt <= 0) {
540 int ret;
541
542 wake_batch = READ_ONCE(sbq->wake_batch);
543
544 /*
545 * Pairs with the memory barrier in sbitmap_queue_resize() to
546 * ensure that we see the batch size update before the wait
547 * count is reset.
548 */
549 smp_mb__before_atomic();
550
551 /*
552 * For concurrent callers of this, the one that failed the
553 * atomic_cmpxhcg() race should call this function again
554 * to wakeup a new batch on a different 'ws'.
555 */
556 ret = atomic_cmpxchg(&ws->wait_cnt, wait_cnt, wake_batch);
557 if (ret == wait_cnt) {
558 sbq_index_atomic_inc(&sbq->wake_index);
559 wake_up_nr(&ws->wait, wake_batch);
560 return false;
561 }
562
563 return true;
564 }
565
566 return false;
567}
568
569void sbitmap_queue_wake_up(struct sbitmap_queue *sbq)
570{
571 while (__sbq_wake_up(sbq))
572 ;
573}
574EXPORT_SYMBOL_GPL(sbitmap_queue_wake_up);
575
576void sbitmap_queue_clear(struct sbitmap_queue *sbq, unsigned int nr,
577 unsigned int cpu)
578{
579 /*
580 * Once the clear bit is set, the bit may be allocated out.
581 *
582 * Orders READ/WRITE on the asssociated instance(such as request
583 * of blk_mq) by this bit for avoiding race with re-allocation,
584 * and its pair is the memory barrier implied in __sbitmap_get_word.
585 *
586 * One invariant is that the clear bit has to be zero when the bit
587 * is in use.
588 */
589 smp_mb__before_atomic();
590 sbitmap_deferred_clear_bit(&sbq->sb, nr);
591
592 /*
593 * Pairs with the memory barrier in set_current_state() to ensure the
594 * proper ordering of clear_bit_unlock()/waitqueue_active() in the waker
595 * and test_and_set_bit_lock()/prepare_to_wait()/finish_wait() in the
596 * waiter. See the comment on waitqueue_active().
597 */
598 smp_mb__after_atomic();
599 sbitmap_queue_wake_up(sbq);
600
601 if (likely(!sbq->round_robin && nr < sbq->sb.depth))
602 *per_cpu_ptr(sbq->alloc_hint, cpu) = nr;
603}
604EXPORT_SYMBOL_GPL(sbitmap_queue_clear);
605
606void sbitmap_queue_wake_all(struct sbitmap_queue *sbq)
607{
608 int i, wake_index;
609
610 /*
611 * Pairs with the memory barrier in set_current_state() like in
612 * sbitmap_queue_wake_up().
613 */
614 smp_mb();
615 wake_index = atomic_read(&sbq->wake_index);
616 for (i = 0; i < SBQ_WAIT_QUEUES; i++) {
617 struct sbq_wait_state *ws = &sbq->ws[wake_index];
618
619 if (waitqueue_active(&ws->wait))
620 wake_up(&ws->wait);
621
622 wake_index = sbq_index_inc(wake_index);
623 }
624}
625EXPORT_SYMBOL_GPL(sbitmap_queue_wake_all);
626
627void sbitmap_queue_show(struct sbitmap_queue *sbq, struct seq_file *m)
628{
629 bool first;
630 int i;
631
632 sbitmap_show(&sbq->sb, m);
633
634 seq_puts(m, "alloc_hint={");
635 first = true;
636 for_each_possible_cpu(i) {
637 if (!first)
638 seq_puts(m, ", ");
639 first = false;
640 seq_printf(m, "%u", *per_cpu_ptr(sbq->alloc_hint, i));
641 }
642 seq_puts(m, "}\n");
643
644 seq_printf(m, "wake_batch=%u\n", sbq->wake_batch);
645 seq_printf(m, "wake_index=%d\n", atomic_read(&sbq->wake_index));
646 seq_printf(m, "ws_active=%d\n", atomic_read(&sbq->ws_active));
647
648 seq_puts(m, "ws={\n");
649 for (i = 0; i < SBQ_WAIT_QUEUES; i++) {
650 struct sbq_wait_state *ws = &sbq->ws[i];
651
652 seq_printf(m, "\t{.wait_cnt=%d, .wait=%s},\n",
653 atomic_read(&ws->wait_cnt),
654 waitqueue_active(&ws->wait) ? "active" : "inactive");
655 }
656 seq_puts(m, "}\n");
657
658 seq_printf(m, "round_robin=%d\n", sbq->round_robin);
659 seq_printf(m, "min_shallow_depth=%u\n", sbq->min_shallow_depth);
660}
661EXPORT_SYMBOL_GPL(sbitmap_queue_show);
662
663void sbitmap_add_wait_queue(struct sbitmap_queue *sbq,
664 struct sbq_wait_state *ws,
665 struct sbq_wait *sbq_wait)
666{
667 if (!sbq_wait->sbq) {
668 sbq_wait->sbq = sbq;
669 atomic_inc(&sbq->ws_active);
670 }
671 add_wait_queue(&ws->wait, &sbq_wait->wait);
672}
673EXPORT_SYMBOL_GPL(sbitmap_add_wait_queue);
674
675void sbitmap_del_wait_queue(struct sbq_wait *sbq_wait)
676{
677 list_del_init(&sbq_wait->wait.entry);
678 if (sbq_wait->sbq) {
679 atomic_dec(&sbq_wait->sbq->ws_active);
680 sbq_wait->sbq = NULL;
681 }
682}
683EXPORT_SYMBOL_GPL(sbitmap_del_wait_queue);
684
685void sbitmap_prepare_to_wait(struct sbitmap_queue *sbq,
686 struct sbq_wait_state *ws,
687 struct sbq_wait *sbq_wait, int state)
688{
689 if (!sbq_wait->sbq) {
690 atomic_inc(&sbq->ws_active);
691 sbq_wait->sbq = sbq;
692 }
693 prepare_to_wait_exclusive(&ws->wait, &sbq_wait->wait, state);
694}
695EXPORT_SYMBOL_GPL(sbitmap_prepare_to_wait);
696
697void sbitmap_finish_wait(struct sbitmap_queue *sbq, struct sbq_wait_state *ws,
698 struct sbq_wait *sbq_wait)
699{
700 finish_wait(&ws->wait, &sbq_wait->wait);
701 if (sbq_wait->sbq) {
702 atomic_dec(&sbq->ws_active);
703 sbq_wait->sbq = NULL;
704 }
705}
706EXPORT_SYMBOL_GPL(sbitmap_finish_wait);
1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * Copyright (C) 2016 Facebook
4 * Copyright (C) 2013-2014 Jens Axboe
5 */
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 move
62 */
63static inline bool sbitmap_deferred_clear(struct sbitmap_word *map)
64{
65 unsigned long mask;
66
67 if (!READ_ONCE(map->cleared))
68 return false;
69
70 /*
71 * First get a stable cleared mask, setting the old mask to 0.
72 */
73 mask = xchg(&map->cleared, 0);
74
75 /*
76 * Now clear the masked bits in our free word
77 */
78 atomic_long_andnot(mask, (atomic_long_t *)&map->word);
79 BUILD_BUG_ON(sizeof(atomic_long_t) != sizeof(map->word));
80 return true;
81}
82
83int sbitmap_init_node(struct sbitmap *sb, unsigned int depth, int shift,
84 gfp_t flags, int node, bool round_robin,
85 bool alloc_hint)
86{
87 unsigned int bits_per_word;
88
89 if (shift < 0)
90 shift = sbitmap_calculate_shift(depth);
91
92 bits_per_word = 1U << shift;
93 if (bits_per_word > BITS_PER_LONG)
94 return -EINVAL;
95
96 sb->shift = shift;
97 sb->depth = depth;
98 sb->map_nr = DIV_ROUND_UP(sb->depth, bits_per_word);
99 sb->round_robin = round_robin;
100
101 if (depth == 0) {
102 sb->map = NULL;
103 return 0;
104 }
105
106 if (alloc_hint) {
107 if (init_alloc_hint(sb, flags))
108 return -ENOMEM;
109 } else {
110 sb->alloc_hint = NULL;
111 }
112
113 sb->map = kvzalloc_node(sb->map_nr * sizeof(*sb->map), flags, node);
114 if (!sb->map) {
115 free_percpu(sb->alloc_hint);
116 return -ENOMEM;
117 }
118
119 return 0;
120}
121EXPORT_SYMBOL_GPL(sbitmap_init_node);
122
123void sbitmap_resize(struct sbitmap *sb, unsigned int depth)
124{
125 unsigned int bits_per_word = 1U << sb->shift;
126 unsigned int i;
127
128 for (i = 0; i < sb->map_nr; i++)
129 sbitmap_deferred_clear(&sb->map[i]);
130
131 sb->depth = depth;
132 sb->map_nr = DIV_ROUND_UP(sb->depth, bits_per_word);
133}
134EXPORT_SYMBOL_GPL(sbitmap_resize);
135
136static int __sbitmap_get_word(unsigned long *word, unsigned long depth,
137 unsigned int hint, bool wrap)
138{
139 int nr;
140
141 /* don't wrap if starting from 0 */
142 wrap = wrap && hint;
143
144 while (1) {
145 nr = find_next_zero_bit(word, depth, hint);
146 if (unlikely(nr >= depth)) {
147 /*
148 * We started with an offset, and we didn't reset the
149 * offset to 0 in a failure case, so start from 0 to
150 * exhaust the map.
151 */
152 if (hint && wrap) {
153 hint = 0;
154 continue;
155 }
156 return -1;
157 }
158
159 if (!test_and_set_bit_lock(nr, word))
160 break;
161
162 hint = nr + 1;
163 if (hint >= depth - 1)
164 hint = 0;
165 }
166
167 return nr;
168}
169
170static int sbitmap_find_bit_in_word(struct sbitmap_word *map,
171 unsigned int depth,
172 unsigned int alloc_hint,
173 bool wrap)
174{
175 int nr;
176
177 do {
178 nr = __sbitmap_get_word(&map->word, depth,
179 alloc_hint, wrap);
180 if (nr != -1)
181 break;
182 if (!sbitmap_deferred_clear(map))
183 break;
184 } while (1);
185
186 return nr;
187}
188
189static int sbitmap_find_bit(struct sbitmap *sb,
190 unsigned int depth,
191 unsigned int index,
192 unsigned int alloc_hint,
193 bool wrap)
194{
195 unsigned int i;
196 int nr = -1;
197
198 for (i = 0; i < sb->map_nr; i++) {
199 nr = sbitmap_find_bit_in_word(&sb->map[index],
200 min_t(unsigned int,
201 __map_depth(sb, index),
202 depth),
203 alloc_hint, wrap);
204
205 if (nr != -1) {
206 nr += index << sb->shift;
207 break;
208 }
209
210 /* Jump to next index. */
211 alloc_hint = 0;
212 if (++index >= sb->map_nr)
213 index = 0;
214 }
215
216 return nr;
217}
218
219static int __sbitmap_get(struct sbitmap *sb, unsigned int alloc_hint)
220{
221 unsigned int index;
222
223 index = SB_NR_TO_INDEX(sb, alloc_hint);
224
225 /*
226 * Unless we're doing round robin tag allocation, just use the
227 * alloc_hint to find the right word index. No point in looping
228 * twice in find_next_zero_bit() for that case.
229 */
230 if (sb->round_robin)
231 alloc_hint = SB_NR_TO_BIT(sb, alloc_hint);
232 else
233 alloc_hint = 0;
234
235 return sbitmap_find_bit(sb, UINT_MAX, index, alloc_hint,
236 !sb->round_robin);
237}
238
239int sbitmap_get(struct sbitmap *sb)
240{
241 int nr;
242 unsigned int hint, depth;
243
244 if (WARN_ON_ONCE(unlikely(!sb->alloc_hint)))
245 return -1;
246
247 depth = READ_ONCE(sb->depth);
248 hint = update_alloc_hint_before_get(sb, depth);
249 nr = __sbitmap_get(sb, hint);
250 update_alloc_hint_after_get(sb, depth, hint, nr);
251
252 return nr;
253}
254EXPORT_SYMBOL_GPL(sbitmap_get);
255
256static int __sbitmap_get_shallow(struct sbitmap *sb,
257 unsigned int alloc_hint,
258 unsigned long shallow_depth)
259{
260 unsigned int index;
261
262 index = SB_NR_TO_INDEX(sb, alloc_hint);
263 alloc_hint = SB_NR_TO_BIT(sb, alloc_hint);
264
265 return sbitmap_find_bit(sb, shallow_depth, index, alloc_hint, true);
266}
267
268int sbitmap_get_shallow(struct sbitmap *sb, unsigned long shallow_depth)
269{
270 int nr;
271 unsigned int hint, depth;
272
273 if (WARN_ON_ONCE(unlikely(!sb->alloc_hint)))
274 return -1;
275
276 depth = READ_ONCE(sb->depth);
277 hint = update_alloc_hint_before_get(sb, depth);
278 nr = __sbitmap_get_shallow(sb, hint, shallow_depth);
279 update_alloc_hint_after_get(sb, depth, hint, nr);
280
281 return nr;
282}
283EXPORT_SYMBOL_GPL(sbitmap_get_shallow);
284
285bool sbitmap_any_bit_set(const struct sbitmap *sb)
286{
287 unsigned int i;
288
289 for (i = 0; i < sb->map_nr; i++) {
290 if (sb->map[i].word & ~sb->map[i].cleared)
291 return true;
292 }
293 return false;
294}
295EXPORT_SYMBOL_GPL(sbitmap_any_bit_set);
296
297static unsigned int __sbitmap_weight(const struct sbitmap *sb, bool set)
298{
299 unsigned int i, weight = 0;
300
301 for (i = 0; i < sb->map_nr; i++) {
302 const struct sbitmap_word *word = &sb->map[i];
303 unsigned int word_depth = __map_depth(sb, i);
304
305 if (set)
306 weight += bitmap_weight(&word->word, word_depth);
307 else
308 weight += bitmap_weight(&word->cleared, word_depth);
309 }
310 return weight;
311}
312
313static unsigned int sbitmap_cleared(const struct sbitmap *sb)
314{
315 return __sbitmap_weight(sb, false);
316}
317
318unsigned int sbitmap_weight(const struct sbitmap *sb)
319{
320 return __sbitmap_weight(sb, true) - sbitmap_cleared(sb);
321}
322EXPORT_SYMBOL_GPL(sbitmap_weight);
323
324void sbitmap_show(struct sbitmap *sb, struct seq_file *m)
325{
326 seq_printf(m, "depth=%u\n", sb->depth);
327 seq_printf(m, "busy=%u\n", sbitmap_weight(sb));
328 seq_printf(m, "cleared=%u\n", sbitmap_cleared(sb));
329 seq_printf(m, "bits_per_word=%u\n", 1U << sb->shift);
330 seq_printf(m, "map_nr=%u\n", sb->map_nr);
331}
332EXPORT_SYMBOL_GPL(sbitmap_show);
333
334static inline void emit_byte(struct seq_file *m, unsigned int offset, u8 byte)
335{
336 if ((offset & 0xf) == 0) {
337 if (offset != 0)
338 seq_putc(m, '\n');
339 seq_printf(m, "%08x:", offset);
340 }
341 if ((offset & 0x1) == 0)
342 seq_putc(m, ' ');
343 seq_printf(m, "%02x", byte);
344}
345
346void sbitmap_bitmap_show(struct sbitmap *sb, struct seq_file *m)
347{
348 u8 byte = 0;
349 unsigned int byte_bits = 0;
350 unsigned int offset = 0;
351 int i;
352
353 for (i = 0; i < sb->map_nr; i++) {
354 unsigned long word = READ_ONCE(sb->map[i].word);
355 unsigned long cleared = READ_ONCE(sb->map[i].cleared);
356 unsigned int word_bits = __map_depth(sb, i);
357
358 word &= ~cleared;
359
360 while (word_bits > 0) {
361 unsigned int bits = min(8 - byte_bits, word_bits);
362
363 byte |= (word & (BIT(bits) - 1)) << byte_bits;
364 byte_bits += bits;
365 if (byte_bits == 8) {
366 emit_byte(m, offset, byte);
367 byte = 0;
368 byte_bits = 0;
369 offset++;
370 }
371 word >>= bits;
372 word_bits -= bits;
373 }
374 }
375 if (byte_bits) {
376 emit_byte(m, offset, byte);
377 offset++;
378 }
379 if (offset)
380 seq_putc(m, '\n');
381}
382EXPORT_SYMBOL_GPL(sbitmap_bitmap_show);
383
384static unsigned int sbq_calc_wake_batch(struct sbitmap_queue *sbq,
385 unsigned int depth)
386{
387 unsigned int wake_batch;
388 unsigned int shallow_depth;
389
390 /*
391 * Each full word of the bitmap has bits_per_word bits, and there might
392 * be a partial word. There are depth / bits_per_word full words and
393 * depth % bits_per_word bits left over. In bitwise arithmetic:
394 *
395 * bits_per_word = 1 << shift
396 * depth / bits_per_word = depth >> shift
397 * depth % bits_per_word = depth & ((1 << shift) - 1)
398 *
399 * Each word can be limited to sbq->min_shallow_depth bits.
400 */
401 shallow_depth = min(1U << sbq->sb.shift, sbq->min_shallow_depth);
402 depth = ((depth >> sbq->sb.shift) * shallow_depth +
403 min(depth & ((1U << sbq->sb.shift) - 1), shallow_depth));
404 wake_batch = clamp_t(unsigned int, depth / SBQ_WAIT_QUEUES, 1,
405 SBQ_WAKE_BATCH);
406
407 return wake_batch;
408}
409
410int sbitmap_queue_init_node(struct sbitmap_queue *sbq, unsigned int depth,
411 int shift, bool round_robin, gfp_t flags, int node)
412{
413 int ret;
414 int i;
415
416 ret = sbitmap_init_node(&sbq->sb, depth, shift, flags, node,
417 round_robin, true);
418 if (ret)
419 return ret;
420
421 sbq->min_shallow_depth = UINT_MAX;
422 sbq->wake_batch = sbq_calc_wake_batch(sbq, depth);
423 atomic_set(&sbq->wake_index, 0);
424 atomic_set(&sbq->ws_active, 0);
425 atomic_set(&sbq->completion_cnt, 0);
426 atomic_set(&sbq->wakeup_cnt, 0);
427
428 sbq->ws = kzalloc_node(SBQ_WAIT_QUEUES * sizeof(*sbq->ws), flags, node);
429 if (!sbq->ws) {
430 sbitmap_free(&sbq->sb);
431 return -ENOMEM;
432 }
433
434 for (i = 0; i < SBQ_WAIT_QUEUES; i++)
435 init_waitqueue_head(&sbq->ws[i].wait);
436
437 return 0;
438}
439EXPORT_SYMBOL_GPL(sbitmap_queue_init_node);
440
441static void sbitmap_queue_update_wake_batch(struct sbitmap_queue *sbq,
442 unsigned int depth)
443{
444 unsigned int wake_batch;
445
446 wake_batch = sbq_calc_wake_batch(sbq, depth);
447 if (sbq->wake_batch != wake_batch)
448 WRITE_ONCE(sbq->wake_batch, wake_batch);
449}
450
451void sbitmap_queue_recalculate_wake_batch(struct sbitmap_queue *sbq,
452 unsigned int users)
453{
454 unsigned int wake_batch;
455 unsigned int depth = (sbq->sb.depth + users - 1) / users;
456
457 wake_batch = clamp_val(depth / SBQ_WAIT_QUEUES,
458 1, SBQ_WAKE_BATCH);
459
460 WRITE_ONCE(sbq->wake_batch, wake_batch);
461}
462EXPORT_SYMBOL_GPL(sbitmap_queue_recalculate_wake_batch);
463
464void sbitmap_queue_resize(struct sbitmap_queue *sbq, unsigned int depth)
465{
466 sbitmap_queue_update_wake_batch(sbq, depth);
467 sbitmap_resize(&sbq->sb, depth);
468}
469EXPORT_SYMBOL_GPL(sbitmap_queue_resize);
470
471int __sbitmap_queue_get(struct sbitmap_queue *sbq)
472{
473 return sbitmap_get(&sbq->sb);
474}
475EXPORT_SYMBOL_GPL(__sbitmap_queue_get);
476
477unsigned long __sbitmap_queue_get_batch(struct sbitmap_queue *sbq, int nr_tags,
478 unsigned int *offset)
479{
480 struct sbitmap *sb = &sbq->sb;
481 unsigned int hint, depth;
482 unsigned long index, nr;
483 int i;
484
485 if (unlikely(sb->round_robin))
486 return 0;
487
488 depth = READ_ONCE(sb->depth);
489 hint = update_alloc_hint_before_get(sb, depth);
490
491 index = SB_NR_TO_INDEX(sb, hint);
492
493 for (i = 0; i < sb->map_nr; i++) {
494 struct sbitmap_word *map = &sb->map[index];
495 unsigned long get_mask;
496 unsigned int map_depth = __map_depth(sb, index);
497
498 sbitmap_deferred_clear(map);
499 if (map->word == (1UL << (map_depth - 1)) - 1)
500 goto next;
501
502 nr = find_first_zero_bit(&map->word, map_depth);
503 if (nr + nr_tags <= map_depth) {
504 atomic_long_t *ptr = (atomic_long_t *) &map->word;
505 unsigned long val;
506
507 get_mask = ((1UL << nr_tags) - 1) << nr;
508 val = READ_ONCE(map->word);
509 while (!atomic_long_try_cmpxchg(ptr, &val,
510 get_mask | val))
511 ;
512 get_mask = (get_mask & ~val) >> nr;
513 if (get_mask) {
514 *offset = nr + (index << sb->shift);
515 update_alloc_hint_after_get(sb, depth, hint,
516 *offset + nr_tags - 1);
517 return get_mask;
518 }
519 }
520next:
521 /* Jump to next index. */
522 if (++index >= sb->map_nr)
523 index = 0;
524 }
525
526 return 0;
527}
528
529int sbitmap_queue_get_shallow(struct sbitmap_queue *sbq,
530 unsigned int shallow_depth)
531{
532 WARN_ON_ONCE(shallow_depth < sbq->min_shallow_depth);
533
534 return sbitmap_get_shallow(&sbq->sb, shallow_depth);
535}
536EXPORT_SYMBOL_GPL(sbitmap_queue_get_shallow);
537
538void sbitmap_queue_min_shallow_depth(struct sbitmap_queue *sbq,
539 unsigned int min_shallow_depth)
540{
541 sbq->min_shallow_depth = min_shallow_depth;
542 sbitmap_queue_update_wake_batch(sbq, sbq->sb.depth);
543}
544EXPORT_SYMBOL_GPL(sbitmap_queue_min_shallow_depth);
545
546static void __sbitmap_queue_wake_up(struct sbitmap_queue *sbq, int nr)
547{
548 int i, wake_index, woken;
549
550 if (!atomic_read(&sbq->ws_active))
551 return;
552
553 wake_index = atomic_read(&sbq->wake_index);
554 for (i = 0; i < SBQ_WAIT_QUEUES; i++) {
555 struct sbq_wait_state *ws = &sbq->ws[wake_index];
556
557 /*
558 * Advance the index before checking the current queue.
559 * It improves fairness, by ensuring the queue doesn't
560 * need to be fully emptied before trying to wake up
561 * from the next one.
562 */
563 wake_index = sbq_index_inc(wake_index);
564
565 if (waitqueue_active(&ws->wait)) {
566 woken = wake_up_nr(&ws->wait, nr);
567 if (woken == nr)
568 break;
569 nr -= woken;
570 }
571 }
572
573 if (wake_index != atomic_read(&sbq->wake_index))
574 atomic_set(&sbq->wake_index, wake_index);
575}
576
577void sbitmap_queue_wake_up(struct sbitmap_queue *sbq, int nr)
578{
579 unsigned int wake_batch = READ_ONCE(sbq->wake_batch);
580 unsigned int wakeups;
581
582 if (!atomic_read(&sbq->ws_active))
583 return;
584
585 atomic_add(nr, &sbq->completion_cnt);
586 wakeups = atomic_read(&sbq->wakeup_cnt);
587
588 do {
589 if (atomic_read(&sbq->completion_cnt) - wakeups < wake_batch)
590 return;
591 } while (!atomic_try_cmpxchg(&sbq->wakeup_cnt,
592 &wakeups, wakeups + wake_batch));
593
594 __sbitmap_queue_wake_up(sbq, wake_batch);
595}
596EXPORT_SYMBOL_GPL(sbitmap_queue_wake_up);
597
598static inline void sbitmap_update_cpu_hint(struct sbitmap *sb, int cpu, int tag)
599{
600 if (likely(!sb->round_robin && tag < sb->depth))
601 data_race(*per_cpu_ptr(sb->alloc_hint, cpu) = tag);
602}
603
604void sbitmap_queue_clear_batch(struct sbitmap_queue *sbq, int offset,
605 int *tags, int nr_tags)
606{
607 struct sbitmap *sb = &sbq->sb;
608 unsigned long *addr = NULL;
609 unsigned long mask = 0;
610 int i;
611
612 smp_mb__before_atomic();
613 for (i = 0; i < nr_tags; i++) {
614 const int tag = tags[i] - offset;
615 unsigned long *this_addr;
616
617 /* since we're clearing a batch, skip the deferred map */
618 this_addr = &sb->map[SB_NR_TO_INDEX(sb, tag)].word;
619 if (!addr) {
620 addr = this_addr;
621 } else if (addr != this_addr) {
622 atomic_long_andnot(mask, (atomic_long_t *) addr);
623 mask = 0;
624 addr = this_addr;
625 }
626 mask |= (1UL << SB_NR_TO_BIT(sb, tag));
627 }
628
629 if (mask)
630 atomic_long_andnot(mask, (atomic_long_t *) addr);
631
632 smp_mb__after_atomic();
633 sbitmap_queue_wake_up(sbq, nr_tags);
634 sbitmap_update_cpu_hint(&sbq->sb, raw_smp_processor_id(),
635 tags[nr_tags - 1] - offset);
636}
637
638void sbitmap_queue_clear(struct sbitmap_queue *sbq, unsigned int nr,
639 unsigned int cpu)
640{
641 /*
642 * Once the clear bit is set, the bit may be allocated out.
643 *
644 * Orders READ/WRITE on the associated instance(such as request
645 * of blk_mq) by this bit for avoiding race with re-allocation,
646 * and its pair is the memory barrier implied in __sbitmap_get_word.
647 *
648 * One invariant is that the clear bit has to be zero when the bit
649 * is in use.
650 */
651 smp_mb__before_atomic();
652 sbitmap_deferred_clear_bit(&sbq->sb, nr);
653
654 /*
655 * Pairs with the memory barrier in set_current_state() to ensure the
656 * proper ordering of clear_bit_unlock()/waitqueue_active() in the waker
657 * and test_and_set_bit_lock()/prepare_to_wait()/finish_wait() in the
658 * waiter. See the comment on waitqueue_active().
659 */
660 smp_mb__after_atomic();
661 sbitmap_queue_wake_up(sbq, 1);
662 sbitmap_update_cpu_hint(&sbq->sb, cpu, nr);
663}
664EXPORT_SYMBOL_GPL(sbitmap_queue_clear);
665
666void sbitmap_queue_wake_all(struct sbitmap_queue *sbq)
667{
668 int i, wake_index;
669
670 /*
671 * Pairs with the memory barrier in set_current_state() like in
672 * sbitmap_queue_wake_up().
673 */
674 smp_mb();
675 wake_index = atomic_read(&sbq->wake_index);
676 for (i = 0; i < SBQ_WAIT_QUEUES; i++) {
677 struct sbq_wait_state *ws = &sbq->ws[wake_index];
678
679 if (waitqueue_active(&ws->wait))
680 wake_up(&ws->wait);
681
682 wake_index = sbq_index_inc(wake_index);
683 }
684}
685EXPORT_SYMBOL_GPL(sbitmap_queue_wake_all);
686
687void sbitmap_queue_show(struct sbitmap_queue *sbq, struct seq_file *m)
688{
689 bool first;
690 int i;
691
692 sbitmap_show(&sbq->sb, m);
693
694 seq_puts(m, "alloc_hint={");
695 first = true;
696 for_each_possible_cpu(i) {
697 if (!first)
698 seq_puts(m, ", ");
699 first = false;
700 seq_printf(m, "%u", *per_cpu_ptr(sbq->sb.alloc_hint, i));
701 }
702 seq_puts(m, "}\n");
703
704 seq_printf(m, "wake_batch=%u\n", sbq->wake_batch);
705 seq_printf(m, "wake_index=%d\n", atomic_read(&sbq->wake_index));
706 seq_printf(m, "ws_active=%d\n", atomic_read(&sbq->ws_active));
707
708 seq_puts(m, "ws={\n");
709 for (i = 0; i < SBQ_WAIT_QUEUES; i++) {
710 struct sbq_wait_state *ws = &sbq->ws[i];
711 seq_printf(m, "\t{.wait=%s},\n",
712 waitqueue_active(&ws->wait) ? "active" : "inactive");
713 }
714 seq_puts(m, "}\n");
715
716 seq_printf(m, "round_robin=%d\n", sbq->sb.round_robin);
717 seq_printf(m, "min_shallow_depth=%u\n", sbq->min_shallow_depth);
718}
719EXPORT_SYMBOL_GPL(sbitmap_queue_show);
720
721void sbitmap_add_wait_queue(struct sbitmap_queue *sbq,
722 struct sbq_wait_state *ws,
723 struct sbq_wait *sbq_wait)
724{
725 if (!sbq_wait->sbq) {
726 sbq_wait->sbq = sbq;
727 atomic_inc(&sbq->ws_active);
728 add_wait_queue(&ws->wait, &sbq_wait->wait);
729 }
730}
731EXPORT_SYMBOL_GPL(sbitmap_add_wait_queue);
732
733void sbitmap_del_wait_queue(struct sbq_wait *sbq_wait)
734{
735 list_del_init(&sbq_wait->wait.entry);
736 if (sbq_wait->sbq) {
737 atomic_dec(&sbq_wait->sbq->ws_active);
738 sbq_wait->sbq = NULL;
739 }
740}
741EXPORT_SYMBOL_GPL(sbitmap_del_wait_queue);
742
743void sbitmap_prepare_to_wait(struct sbitmap_queue *sbq,
744 struct sbq_wait_state *ws,
745 struct sbq_wait *sbq_wait, int state)
746{
747 if (!sbq_wait->sbq) {
748 atomic_inc(&sbq->ws_active);
749 sbq_wait->sbq = sbq;
750 }
751 prepare_to_wait_exclusive(&ws->wait, &sbq_wait->wait, state);
752}
753EXPORT_SYMBOL_GPL(sbitmap_prepare_to_wait);
754
755void sbitmap_finish_wait(struct sbitmap_queue *sbq, struct sbq_wait_state *ws,
756 struct sbq_wait *sbq_wait)
757{
758 finish_wait(&ws->wait, &sbq_wait->wait);
759 if (sbq_wait->sbq) {
760 atomic_dec(&sbq->ws_active);
761 sbq_wait->sbq = NULL;
762 }
763}
764EXPORT_SYMBOL_GPL(sbitmap_finish_wait);