lib/sbitmap.c

   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 static 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) = prandom_u32() % depth;
  25         }
  26         return 0;
  27 }
  28
  29 static 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 ? prandom_u32() % depth : 0;
  37                 this_cpu_write(*sb->alloc_hint, hint);
  38         }
  39
  40         return hint;
  41 }
  42
  43 static 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  */
  63 static 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
  83 int 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 }
 121 EXPORT_SYMBOL_GPL(sbitmap_init_node);
 122
 123 void 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 }
 134 EXPORT_SYMBOL_GPL(sbitmap_resize);
 135
 136 static 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
 170 static int sbitmap_find_bit_in_index(struct sbitmap *sb, int index,
 171                                      unsigned int alloc_hint)
 172 {
 173         struct sbitmap_word *map = &sb->map[index];
 174         int nr;
 175
 176         do {
 177                 nr = __sbitmap_get_word(&map->word, __map_depth(sb, index),
 178                                         alloc_hint, !sb->round_robin);
 179                 if (nr != -1)
 180                         break;
 181                 if (!sbitmap_deferred_clear(map))
 182                         break;
 183         } while (1);
 184
 185         return nr;
 186 }
 187
 188 static int __sbitmap_get(struct sbitmap *sb, unsigned int alloc_hint)
 189 {
 190         unsigned int i, index;
 191         int nr = -1;
 192
 193         index = SB_NR_TO_INDEX(sb, alloc_hint);
 194
 195         /*
 196          * Unless we're doing round robin tag allocation, just use the
 197          * alloc_hint to find the right word index. No point in looping
 198          * twice in find_next_zero_bit() for that case.
 199          */
 200         if (sb->round_robin)
 201                 alloc_hint = SB_NR_TO_BIT(sb, alloc_hint);
 202         else
 203                 alloc_hint = 0;
 204
 205         for (i = 0; i < sb->map_nr; i++) {
 206                 nr = sbitmap_find_bit_in_index(sb, index, alloc_hint);
 207                 if (nr != -1) {
 208                         nr += index << sb->shift;
 209                         break;
 210                 }
 211
 212                 /* Jump to next index. */
 213                 alloc_hint = 0;
 214                 if (++index >= sb->map_nr)
 215                         index = 0;
 216         }
 217
 218         return nr;
 219 }
 220
 221 int sbitmap_get(struct sbitmap *sb)
 222 {
 223         int nr;
 224         unsigned int hint, depth;
 225
 226         if (WARN_ON_ONCE(unlikely(!sb->alloc_hint)))
 227                 return -1;
 228
 229         depth = READ_ONCE(sb->depth);
 230         hint = update_alloc_hint_before_get(sb, depth);
 231         nr = __sbitmap_get(sb, hint);
 232         update_alloc_hint_after_get(sb, depth, hint, nr);
 233
 234         return nr;
 235 }
 236 EXPORT_SYMBOL_GPL(sbitmap_get);
 237
 238 static int __sbitmap_get_shallow(struct sbitmap *sb,
 239                                  unsigned int alloc_hint,
 240                                  unsigned long shallow_depth)
 241 {
 242         unsigned int i, index;
 243         int nr = -1;
 244
 245         index = SB_NR_TO_INDEX(sb, alloc_hint);
 246
 247         for (i = 0; i < sb->map_nr; i++) {
 248 again:
 249                 nr = __sbitmap_get_word(&sb->map[index].word,
 250                                         min_t(unsigned int,
 251                                               __map_depth(sb, index),
 252                                               shallow_depth),
 253                                         SB_NR_TO_BIT(sb, alloc_hint), true);
 254                 if (nr != -1) {
 255                         nr += index << sb->shift;
 256                         break;
 257                 }
 258
 259                 if (sbitmap_deferred_clear(&sb->map[index]))
 260                         goto again;
 261
 262                 /* Jump to next index. */
 263                 index++;
 264                 alloc_hint = index << sb->shift;
 265
 266                 if (index >= sb->map_nr) {
 267                         index = 0;
 268                         alloc_hint = 0;
 269                 }
 270         }
 271
 272         return nr;
 273 }
 274
 275 int sbitmap_get_shallow(struct sbitmap *sb, unsigned long shallow_depth)
 276 {
 277         int nr;
 278         unsigned int hint, depth;
 279
 280         if (WARN_ON_ONCE(unlikely(!sb->alloc_hint)))
 281                 return -1;
 282
 283         depth = READ_ONCE(sb->depth);
 284         hint = update_alloc_hint_before_get(sb, depth);
 285         nr = __sbitmap_get_shallow(sb, hint, shallow_depth);
 286         update_alloc_hint_after_get(sb, depth, hint, nr);
 287
 288         return nr;
 289 }
 290 EXPORT_SYMBOL_GPL(sbitmap_get_shallow);
 291
 292 bool sbitmap_any_bit_set(const struct sbitmap *sb)
 293 {
 294         unsigned int i;
 295
 296         for (i = 0; i < sb->map_nr; i++) {
 297                 if (sb->map[i].word & ~sb->map[i].cleared)
 298                         return true;
 299         }
 300         return false;
 301 }
 302 EXPORT_SYMBOL_GPL(sbitmap_any_bit_set);
 303
 304 static unsigned int __sbitmap_weight(const struct sbitmap *sb, bool set)
 305 {
 306         unsigned int i, weight = 0;
 307
 308         for (i = 0; i < sb->map_nr; i++) {
 309                 const struct sbitmap_word *word = &sb->map[i];
 310                 unsigned int word_depth = __map_depth(sb, i);
 311
 312                 if (set)
 313                         weight += bitmap_weight(&word->word, word_depth);
 314                 else
 315                         weight += bitmap_weight(&word->cleared, word_depth);
 316         }
 317         return weight;
 318 }
 319
 320 static unsigned int sbitmap_cleared(const struct sbitmap *sb)
 321 {
 322         return __sbitmap_weight(sb, false);
 323 }
 324
 325 unsigned int sbitmap_weight(const struct sbitmap *sb)
 326 {
 327         return __sbitmap_weight(sb, true) - sbitmap_cleared(sb);
 328 }
 329 EXPORT_SYMBOL_GPL(sbitmap_weight);
 330
 331 void sbitmap_show(struct sbitmap *sb, struct seq_file *m)
 332 {
 333         seq_printf(m, "depth=%u\n", sb->depth);
 334         seq_printf(m, "busy=%u\n", sbitmap_weight(sb));
 335         seq_printf(m, "cleared=%u\n", sbitmap_cleared(sb));
 336         seq_printf(m, "bits_per_word=%u\n", 1U << sb->shift);
 337         seq_printf(m, "map_nr=%u\n", sb->map_nr);
 338 }
 339 EXPORT_SYMBOL_GPL(sbitmap_show);
 340
 341 static inline void emit_byte(struct seq_file *m, unsigned int offset, u8 byte)
 342 {
 343         if ((offset & 0xf) == 0) {
 344                 if (offset != 0)
 345                         seq_putc(m, '\n');
 346                 seq_printf(m, "%08x:", offset);
 347         }
 348         if ((offset & 0x1) == 0)
 349                 seq_putc(m, ' ');
 350         seq_printf(m, "%02x", byte);
 351 }
 352
 353 void sbitmap_bitmap_show(struct sbitmap *sb, struct seq_file *m)
 354 {
 355         u8 byte = 0;
 356         unsigned int byte_bits = 0;
 357         unsigned int offset = 0;
 358         int i;
 359
 360         for (i = 0; i < sb->map_nr; i++) {
 361                 unsigned long word = READ_ONCE(sb->map[i].word);
 362                 unsigned long cleared = READ_ONCE(sb->map[i].cleared);
 363                 unsigned int word_bits = __map_depth(sb, i);
 364
 365                 word &= ~cleared;
 366
 367                 while (word_bits > 0) {
 368                         unsigned int bits = min(8 - byte_bits, word_bits);
 369
 370                         byte |= (word & (BIT(bits) - 1)) << byte_bits;
 371                         byte_bits += bits;
 372                         if (byte_bits == 8) {
 373                                 emit_byte(m, offset, byte);
 374                                 byte = 0;
 375                                 byte_bits = 0;
 376                                 offset++;
 377                         }
 378                         word >>= bits;
 379                         word_bits -= bits;
 380                 }
 381         }
 382         if (byte_bits) {
 383                 emit_byte(m, offset, byte);
 384                 offset++;
 385         }
 386         if (offset)
 387                 seq_putc(m, '\n');
 388 }
 389 EXPORT_SYMBOL_GPL(sbitmap_bitmap_show);
 390
 391 static unsigned int sbq_calc_wake_batch(struct sbitmap_queue *sbq,
 392                                         unsigned int depth)
 393 {
 394         unsigned int wake_batch;
 395         unsigned int shallow_depth;
 396
 397         /*
 398          * For each batch, we wake up one queue. We need to make sure that our
 399          * batch size is small enough that the full depth of the bitmap,
 400          * potentially limited by a shallow depth, is enough to wake up all of
 401          * the queues.
 402          *
 403          * Each full word of the bitmap has bits_per_word bits, and there might
 404          * be a partial word. There are depth / bits_per_word full words and
 405          * depth % bits_per_word bits left over. In bitwise arithmetic:
 406          *
 407          * bits_per_word = 1 << shift
 408          * depth / bits_per_word = depth >> shift
 409          * depth % bits_per_word = depth & ((1 << shift) - 1)
 410          *
 411          * Each word can be limited to sbq->min_shallow_depth bits.
 412          */
 413         shallow_depth = min(1U << sbq->sb.shift, sbq->min_shallow_depth);
 414         depth = ((depth >> sbq->sb.shift) * shallow_depth +
 415                  min(depth & ((1U << sbq->sb.shift) - 1), shallow_depth));
 416         wake_batch = clamp_t(unsigned int, depth / SBQ_WAIT_QUEUES, 1,
 417                              SBQ_WAKE_BATCH);
 418
 419         return wake_batch;
 420 }
 421
 422 int sbitmap_queue_init_node(struct sbitmap_queue *sbq, unsigned int depth,
 423                             int shift, bool round_robin, gfp_t flags, int node)
 424 {
 425         int ret;
 426         int i;
 427
 428         ret = sbitmap_init_node(&sbq->sb, depth, shift, flags, node,
 429                                 round_robin, true);
 430         if (ret)
 431                 return ret;
 432
 433         sbq->min_shallow_depth = UINT_MAX;
 434         sbq->wake_batch = sbq_calc_wake_batch(sbq, depth);
 435         atomic_set(&sbq->wake_index, 0);
 436         atomic_set(&sbq->ws_active, 0);
 437
 438         sbq->ws = kzalloc_node(SBQ_WAIT_QUEUES * sizeof(*sbq->ws), flags, node);
 439         if (!sbq->ws) {
 440                 sbitmap_free(&sbq->sb);
 441                 return -ENOMEM;
 442         }
 443
 444         for (i = 0; i < SBQ_WAIT_QUEUES; i++) {
 445                 init_waitqueue_head(&sbq->ws[i].wait);
 446                 atomic_set(&sbq->ws[i].wait_cnt, sbq->wake_batch);
 447         }
 448
 449         return 0;
 450 }
 451 EXPORT_SYMBOL_GPL(sbitmap_queue_init_node);
 452
 453 static inline void __sbitmap_queue_update_wake_batch(struct sbitmap_queue *sbq,
 454                                             unsigned int wake_batch)
 455 {
 456         int i;
 457
 458         if (sbq->wake_batch != wake_batch) {
 459                 WRITE_ONCE(sbq->wake_batch, wake_batch);
 460                 /*
 461                  * Pairs with the memory barrier in sbitmap_queue_wake_up()
 462                  * to ensure that the batch size is updated before the wait
 463                  * counts.
 464                  */
 465                 smp_mb();
 466                 for (i = 0; i < SBQ_WAIT_QUEUES; i++)
 467                         atomic_set(&sbq->ws[i].wait_cnt, 1);
 468         }
 469 }
 470
 471 static void sbitmap_queue_update_wake_batch(struct sbitmap_queue *sbq,
 472                                             unsigned int depth)
 473 {
 474         unsigned int wake_batch;
 475
 476         wake_batch = sbq_calc_wake_batch(sbq, depth);
 477         __sbitmap_queue_update_wake_batch(sbq, wake_batch);
 478 }
 479
 480 void sbitmap_queue_recalculate_wake_batch(struct sbitmap_queue *sbq,
 481                                             unsigned int users)
 482 {
 483         unsigned int wake_batch;
 484         unsigned int min_batch;
 485         unsigned int depth = (sbq->sb.depth + users - 1) / users;
 486
 487         min_batch = sbq->sb.depth >= (4 * SBQ_WAIT_QUEUES) ? 4 : 1;
 488
 489         wake_batch = clamp_val(depth / SBQ_WAIT_QUEUES,
 490                         min_batch, SBQ_WAKE_BATCH);
 491         __sbitmap_queue_update_wake_batch(sbq, wake_batch);
 492 }
 493 EXPORT_SYMBOL_GPL(sbitmap_queue_recalculate_wake_batch);
 494
 495 void sbitmap_queue_resize(struct sbitmap_queue *sbq, unsigned int depth)
 496 {
 497         sbitmap_queue_update_wake_batch(sbq, depth);
 498         sbitmap_resize(&sbq->sb, depth);
 499 }
 500 EXPORT_SYMBOL_GPL(sbitmap_queue_resize);
 501
 502 int __sbitmap_queue_get(struct sbitmap_queue *sbq)
 503 {
 504         return sbitmap_get(&sbq->sb);
 505 }
 506 EXPORT_SYMBOL_GPL(__sbitmap_queue_get);
 507
 508 unsigned long __sbitmap_queue_get_batch(struct sbitmap_queue *sbq, int nr_tags,
 509                                         unsigned int *offset)
 510 {
 511         struct sbitmap *sb = &sbq->sb;
 512         unsigned int hint, depth;
 513         unsigned long index, nr;
 514         int i;
 515
 516         if (unlikely(sb->round_robin))
 517                 return 0;
 518
 519         depth = READ_ONCE(sb->depth);
 520         hint = update_alloc_hint_before_get(sb, depth);
 521
 522         index = SB_NR_TO_INDEX(sb, hint);
 523
 524         for (i = 0; i < sb->map_nr; i++) {
 525                 struct sbitmap_word *map = &sb->map[index];
 526                 unsigned long get_mask;
 527                 unsigned int map_depth = __map_depth(sb, index);
 528
 529                 sbitmap_deferred_clear(map);
 530                 if (map->word == (1UL << (map_depth - 1)) - 1)
 531                         goto next;
 532
 533                 nr = find_first_zero_bit(&map->word, map_depth);
 534                 if (nr + nr_tags <= map_depth) {
 535                         atomic_long_t *ptr = (atomic_long_t *) &map->word;
 536                         int map_tags = min_t(int, nr_tags, map_depth);
 537                         unsigned long val, ret;
 538
 539                         get_mask = ((1UL << map_tags) - 1) << nr;
 540                         do {
 541                                 val = READ_ONCE(map->word);
 542                                 if ((val & ~get_mask) != val)
 543                                         goto next;
 544                                 ret = atomic_long_cmpxchg(ptr, val, get_mask | val);
 545                         } while (ret != val);
 546                         get_mask = (get_mask & ~ret) >> nr;
 547                         if (get_mask) {
 548                                 *offset = nr + (index << sb->shift);
 549                                 update_alloc_hint_after_get(sb, depth, hint,
 550                                                         *offset + map_tags - 1);
 551                                 return get_mask;
 552                         }
 553                 }
 554 next:
 555                 /* Jump to next index. */
 556                 if (++index >= sb->map_nr)
 557                         index = 0;
 558         }
 559
 560         return 0;
 561 }
 562
 563 int sbitmap_queue_get_shallow(struct sbitmap_queue *sbq,
 564                               unsigned int shallow_depth)
 565 {
 566         WARN_ON_ONCE(shallow_depth < sbq->min_shallow_depth);
 567
 568         return sbitmap_get_shallow(&sbq->sb, shallow_depth);
 569 }
 570 EXPORT_SYMBOL_GPL(sbitmap_queue_get_shallow);
 571
 572 void sbitmap_queue_min_shallow_depth(struct sbitmap_queue *sbq,
 573                                      unsigned int min_shallow_depth)
 574 {
 575         sbq->min_shallow_depth = min_shallow_depth;
 576         sbitmap_queue_update_wake_batch(sbq, sbq->sb.depth);
 577 }
 578 EXPORT_SYMBOL_GPL(sbitmap_queue_min_shallow_depth);
 579
 580 static struct sbq_wait_state *sbq_wake_ptr(struct sbitmap_queue *sbq)
 581 {
 582         int i, wake_index;
 583
 584         if (!atomic_read(&sbq->ws_active))
 585                 return NULL;
 586
 587         wake_index = atomic_read(&sbq->wake_index);
 588         for (i = 0; i < SBQ_WAIT_QUEUES; i++) {
 589                 struct sbq_wait_state *ws = &sbq->ws[wake_index];
 590
 591                 if (waitqueue_active(&ws->wait)) {
 592                         if (wake_index != atomic_read(&sbq->wake_index))
 593                                 atomic_set(&sbq->wake_index, wake_index);
 594                         return ws;
 595                 }
 596
 597                 wake_index = sbq_index_inc(wake_index);
 598         }
 599
 600         return NULL;
 601 }
 602
 603 static bool __sbq_wake_up(struct sbitmap_queue *sbq)
 604 {
 605         struct sbq_wait_state *ws;
 606         unsigned int wake_batch;
 607         int wait_cnt;
 608
 609         ws = sbq_wake_ptr(sbq);
 610         if (!ws)
 611                 return false;
 612
 613         wait_cnt = atomic_dec_return(&ws->wait_cnt);
 614         if (wait_cnt <= 0) {
 615                 int ret;
 616
 617                 wake_batch = READ_ONCE(sbq->wake_batch);
 618
 619                 /*
 620                  * Pairs with the memory barrier in sbitmap_queue_resize() to
 621                  * ensure that we see the batch size update before the wait
 622                  * count is reset.
 623                  */
 624                 smp_mb__before_atomic();
 625
 626                 /*
 627                  * For concurrent callers of this, the one that failed the
 628                  * atomic_cmpxhcg() race should call this function again
 629                  * to wakeup a new batch on a different 'ws'.
 630                  */
 631                 ret = atomic_cmpxchg(&ws->wait_cnt, wait_cnt, wake_batch);
 632                 if (ret == wait_cnt) {
 633                         sbq_index_atomic_inc(&sbq->wake_index);
 634                         wake_up_nr(&ws->wait, wake_batch);
 635                         return false;
 636                 }
 637
 638                 return true;
 639         }
 640
 641         return false;
 642 }
 643
 644 void sbitmap_queue_wake_up(struct sbitmap_queue *sbq)
 645 {
 646         while (__sbq_wake_up(sbq))
 647                 ;
 648 }
 649 EXPORT_SYMBOL_GPL(sbitmap_queue_wake_up);
 650
 651 static inline void sbitmap_update_cpu_hint(struct sbitmap *sb, int cpu, int tag)
 652 {
 653         if (likely(!sb->round_robin && tag < sb->depth))
 654                 data_race(*per_cpu_ptr(sb->alloc_hint, cpu) = tag);
 655 }
 656
 657 void sbitmap_queue_clear_batch(struct sbitmap_queue *sbq, int offset,
 658                                 int *tags, int nr_tags)
 659 {
 660         struct sbitmap *sb = &sbq->sb;
 661         unsigned long *addr = NULL;
 662         unsigned long mask = 0;
 663         int i;
 664
 665         smp_mb__before_atomic();
 666         for (i = 0; i < nr_tags; i++) {
 667                 const int tag = tags[i] - offset;
 668                 unsigned long *this_addr;
 669
 670                 /* since we're clearing a batch, skip the deferred map */
 671                 this_addr = &sb->map[SB_NR_TO_INDEX(sb, tag)].word;
 672                 if (!addr) {
 673                         addr = this_addr;
 674                 } else if (addr != this_addr) {
 675                         atomic_long_andnot(mask, (atomic_long_t *) addr);
 676                         mask = 0;
 677                         addr = this_addr;
 678                 }
 679                 mask |= (1UL << SB_NR_TO_BIT(sb, tag));
 680         }
 681
 682         if (mask)
 683                 atomic_long_andnot(mask, (atomic_long_t *) addr);
 684
 685         smp_mb__after_atomic();
 686         sbitmap_queue_wake_up(sbq);
 687         sbitmap_update_cpu_hint(&sbq->sb, raw_smp_processor_id(),
 688                                         tags[nr_tags - 1] - offset);
 689 }
 690
 691 void sbitmap_queue_clear(struct sbitmap_queue *sbq, unsigned int nr,
 692                          unsigned int cpu)
 693 {
 694         /*
 695          * Once the clear bit is set, the bit may be allocated out.
 696          *
 697          * Orders READ/WRITE on the associated instance(such as request
 698          * of blk_mq) by this bit for avoiding race with re-allocation,
 699          * and its pair is the memory barrier implied in __sbitmap_get_word.
 700          *
 701          * One invariant is that the clear bit has to be zero when the bit
 702          * is in use.
 703          */
 704         smp_mb__before_atomic();
 705         sbitmap_deferred_clear_bit(&sbq->sb, nr);
 706
 707         /*
 708          * Pairs with the memory barrier in set_current_state() to ensure the
 709          * proper ordering of clear_bit_unlock()/waitqueue_active() in the waker
 710          * and test_and_set_bit_lock()/prepare_to_wait()/finish_wait() in the
 711          * waiter. See the comment on waitqueue_active().
 712          */
 713         smp_mb__after_atomic();
 714         sbitmap_queue_wake_up(sbq);
 715         sbitmap_update_cpu_hint(&sbq->sb, cpu, nr);
 716 }
 717 EXPORT_SYMBOL_GPL(sbitmap_queue_clear);
 718
 719 void sbitmap_queue_wake_all(struct sbitmap_queue *sbq)
 720 {
 721         int i, wake_index;
 722
 723         /*
 724          * Pairs with the memory barrier in set_current_state() like in
 725          * sbitmap_queue_wake_up().
 726          */
 727         smp_mb();
 728         wake_index = atomic_read(&sbq->wake_index);
 729         for (i = 0; i < SBQ_WAIT_QUEUES; i++) {
 730                 struct sbq_wait_state *ws = &sbq->ws[wake_index];
 731
 732                 if (waitqueue_active(&ws->wait))
 733                         wake_up(&ws->wait);
 734
 735                 wake_index = sbq_index_inc(wake_index);
 736         }
 737 }
 738 EXPORT_SYMBOL_GPL(sbitmap_queue_wake_all);
 739
 740 void sbitmap_queue_show(struct sbitmap_queue *sbq, struct seq_file *m)
 741 {
 742         bool first;
 743         int i;
 744
 745         sbitmap_show(&sbq->sb, m);
 746
 747         seq_puts(m, "alloc_hint={");
 748         first = true;
 749         for_each_possible_cpu(i) {
 750                 if (!first)
 751                         seq_puts(m, ", ");
 752                 first = false;
 753                 seq_printf(m, "%u", *per_cpu_ptr(sbq->sb.alloc_hint, i));
 754         }
 755         seq_puts(m, "}\n");
 756
 757         seq_printf(m, "wake_batch=%u\n", sbq->wake_batch);
 758         seq_printf(m, "wake_index=%d\n", atomic_read(&sbq->wake_index));
 759         seq_printf(m, "ws_active=%d\n", atomic_read(&sbq->ws_active));
 760
 761         seq_puts(m, "ws={\n");
 762         for (i = 0; i < SBQ_WAIT_QUEUES; i++) {
 763                 struct sbq_wait_state *ws = &sbq->ws[i];
 764
 765                 seq_printf(m, "\t{.wait_cnt=%d, .wait=%s},\n",
 766                            atomic_read(&ws->wait_cnt),
 767                            waitqueue_active(&ws->wait) ? "active" : "inactive");
 768         }
 769         seq_puts(m, "}\n");
 770
 771         seq_printf(m, "round_robin=%d\n", sbq->sb.round_robin);
 772         seq_printf(m, "min_shallow_depth=%u\n", sbq->min_shallow_depth);
 773 }
 774 EXPORT_SYMBOL_GPL(sbitmap_queue_show);
 775
 776 void sbitmap_add_wait_queue(struct sbitmap_queue *sbq,
 777                             struct sbq_wait_state *ws,
 778                             struct sbq_wait *sbq_wait)
 779 {
 780         if (!sbq_wait->sbq) {
 781                 sbq_wait->sbq = sbq;
 782                 atomic_inc(&sbq->ws_active);
 783                 add_wait_queue(&ws->wait, &sbq_wait->wait);
 784         }
 785 }
 786 EXPORT_SYMBOL_GPL(sbitmap_add_wait_queue);
 787
 788 void sbitmap_del_wait_queue(struct sbq_wait *sbq_wait)
 789 {
 790         list_del_init(&sbq_wait->wait.entry);
 791         if (sbq_wait->sbq) {
 792                 atomic_dec(&sbq_wait->sbq->ws_active);
 793                 sbq_wait->sbq = NULL;
 794         }
 795 }
 796 EXPORT_SYMBOL_GPL(sbitmap_del_wait_queue);
 797
 798 void sbitmap_prepare_to_wait(struct sbitmap_queue *sbq,
 799                              struct sbq_wait_state *ws,
 800                              struct sbq_wait *sbq_wait, int state)
 801 {
 802         if (!sbq_wait->sbq) {
 803                 atomic_inc(&sbq->ws_active);
 804                 sbq_wait->sbq = sbq;
 805         }
 806         prepare_to_wait_exclusive(&ws->wait, &sbq_wait->wait, state);
 807 }
 808 EXPORT_SYMBOL_GPL(sbitmap_prepare_to_wait);
 809
 810 void sbitmap_finish_wait(struct sbitmap_queue *sbq, struct sbq_wait_state *ws,
 811                          struct sbq_wait *sbq_wait)
 812 {
 813         finish_wait(&ws->wait, &sbq_wait->wait);
 814         if (sbq_wait->sbq) {
 815                 atomic_dec(&sbq->ws_active);
 816                 sbq_wait->sbq = NULL;
 817         }
 818 }
 819 EXPORT_SYMBOL_GPL(sbitmap_finish_wait);