LCOV - code coverage report
Current view: top level - include/linux - sbitmap.h (source / functions) Hit Total Coverage
Test: coverage.info Lines: 0 47 0.0 %
Date: 2023-07-19 18:55:55 Functions: 0 2 0.0 %

          Line data    Source code
       1             : /* SPDX-License-Identifier: GPL-2.0-only */
       2             : /*
       3             :  * Fast and scalable bitmaps.
       4             :  *
       5             :  * Copyright (C) 2016 Facebook
       6             :  * Copyright (C) 2013-2014 Jens Axboe
       7             :  */
       8             : 
       9             : #ifndef __LINUX_SCALE_BITMAP_H
      10             : #define __LINUX_SCALE_BITMAP_H
      11             : 
      12             : #include <linux/atomic.h>
      13             : #include <linux/bitops.h>
      14             : #include <linux/cache.h>
      15             : #include <linux/list.h>
      16             : #include <linux/log2.h>
      17             : #include <linux/minmax.h>
      18             : #include <linux/percpu.h>
      19             : #include <linux/slab.h>
      20             : #include <linux/smp.h>
      21             : #include <linux/types.h>
      22             : #include <linux/wait.h>
      23             : 
      24             : struct seq_file;
      25             : 
      26             : /**
      27             :  * struct sbitmap_word - Word in a &struct sbitmap.
      28             :  */
      29             : struct sbitmap_word {
      30             :         /**
      31             :          * @word: word holding free bits
      32             :          */
      33             :         unsigned long word;
      34             : 
      35             :         /**
      36             :          * @cleared: word holding cleared bits
      37             :          */
      38             :         unsigned long cleared ____cacheline_aligned_in_smp;
      39             : } ____cacheline_aligned_in_smp;
      40             : 
      41             : /**
      42             :  * struct sbitmap - Scalable bitmap.
      43             :  *
      44             :  * A &struct sbitmap is spread over multiple cachelines to avoid ping-pong. This
      45             :  * trades off higher memory usage for better scalability.
      46             :  */
      47             : struct sbitmap {
      48             :         /**
      49             :          * @depth: Number of bits used in the whole bitmap.
      50             :          */
      51             :         unsigned int depth;
      52             : 
      53             :         /**
      54             :          * @shift: log2(number of bits used per word)
      55             :          */
      56             :         unsigned int shift;
      57             : 
      58             :         /**
      59             :          * @map_nr: Number of words (cachelines) being used for the bitmap.
      60             :          */
      61             :         unsigned int map_nr;
      62             : 
      63             :         /**
      64             :          * @round_robin: Allocate bits in strict round-robin order.
      65             :          */
      66             :         bool round_robin;
      67             : 
      68             :         /**
      69             :          * @map: Allocated bitmap.
      70             :          */
      71             :         struct sbitmap_word *map;
      72             : 
      73             :         /*
      74             :          * @alloc_hint: Cache of last successfully allocated or freed bit.
      75             :          *
      76             :          * This is per-cpu, which allows multiple users to stick to different
      77             :          * cachelines until the map is exhausted.
      78             :          */
      79             :         unsigned int __percpu *alloc_hint;
      80             : };
      81             : 
      82             : #define SBQ_WAIT_QUEUES 8
      83             : #define SBQ_WAKE_BATCH 8
      84             : 
      85             : /**
      86             :  * struct sbq_wait_state - Wait queue in a &struct sbitmap_queue.
      87             :  */
      88             : struct sbq_wait_state {
      89             :         /**
      90             :          * @wait: Wait queue.
      91             :          */
      92             :         wait_queue_head_t wait;
      93             : } ____cacheline_aligned_in_smp;
      94             : 
      95             : /**
      96             :  * struct sbitmap_queue - Scalable bitmap with the added ability to wait on free
      97             :  * bits.
      98             :  *
      99             :  * A &struct sbitmap_queue uses multiple wait queues and rolling wakeups to
     100             :  * avoid contention on the wait queue spinlock. This ensures that we don't hit a
     101             :  * scalability wall when we run out of free bits and have to start putting tasks
     102             :  * to sleep.
     103             :  */
     104             : struct sbitmap_queue {
     105             :         /**
     106             :          * @sb: Scalable bitmap.
     107             :          */
     108             :         struct sbitmap sb;
     109             : 
     110             :         /**
     111             :          * @wake_batch: Number of bits which must be freed before we wake up any
     112             :          * waiters.
     113             :          */
     114             :         unsigned int wake_batch;
     115             : 
     116             :         /**
     117             :          * @wake_index: Next wait queue in @ws to wake up.
     118             :          */
     119             :         atomic_t wake_index;
     120             : 
     121             :         /**
     122             :          * @ws: Wait queues.
     123             :          */
     124             :         struct sbq_wait_state *ws;
     125             : 
     126             :         /*
     127             :          * @ws_active: count of currently active ws waitqueues
     128             :          */
     129             :         atomic_t ws_active;
     130             : 
     131             :         /**
     132             :          * @min_shallow_depth: The minimum shallow depth which may be passed to
     133             :          * sbitmap_queue_get_shallow()
     134             :          */
     135             :         unsigned int min_shallow_depth;
     136             : 
     137             :         /**
     138             :          * @completion_cnt: Number of bits cleared passed to the
     139             :          * wakeup function.
     140             :          */
     141             :         atomic_t completion_cnt;
     142             : 
     143             :         /**
     144             :          * @wakeup_cnt: Number of thread wake ups issued.
     145             :          */
     146             :         atomic_t wakeup_cnt;
     147             : };
     148             : 
     149             : /**
     150             :  * sbitmap_init_node() - Initialize a &struct sbitmap on a specific memory node.
     151             :  * @sb: Bitmap to initialize.
     152             :  * @depth: Number of bits to allocate.
     153             :  * @shift: Use 2^@shift bits per word in the bitmap; if a negative number if
     154             :  *         given, a good default is chosen.
     155             :  * @flags: Allocation flags.
     156             :  * @node: Memory node to allocate on.
     157             :  * @round_robin: If true, be stricter about allocation order; always allocate
     158             :  *               starting from the last allocated bit. This is less efficient
     159             :  *               than the default behavior (false).
     160             :  * @alloc_hint: If true, apply percpu hint for where to start searching for
     161             :  *              a free bit.
     162             :  *
     163             :  * Return: Zero on success or negative errno on failure.
     164             :  */
     165             : int sbitmap_init_node(struct sbitmap *sb, unsigned int depth, int shift,
     166             :                       gfp_t flags, int node, bool round_robin, bool alloc_hint);
     167             : 
     168             : /* sbitmap internal helper */
     169             : static inline unsigned int __map_depth(const struct sbitmap *sb, int index)
     170             : {
     171           0 :         if (index == sb->map_nr - 1)
     172           0 :                 return sb->depth - (index << sb->shift);
     173           0 :         return 1U << sb->shift;
     174             : }
     175             : 
     176             : /**
     177             :  * sbitmap_free() - Free memory used by a &struct sbitmap.
     178             :  * @sb: Bitmap to free.
     179             :  */
     180             : static inline void sbitmap_free(struct sbitmap *sb)
     181             : {
     182           0 :         free_percpu(sb->alloc_hint);
     183           0 :         kvfree(sb->map);
     184           0 :         sb->map = NULL;
     185             : }
     186             : 
     187             : /**
     188             :  * sbitmap_resize() - Resize a &struct sbitmap.
     189             :  * @sb: Bitmap to resize.
     190             :  * @depth: New number of bits to resize to.
     191             :  *
     192             :  * Doesn't reallocate anything. It's up to the caller to ensure that the new
     193             :  * depth doesn't exceed the depth that the sb was initialized with.
     194             :  */
     195             : void sbitmap_resize(struct sbitmap *sb, unsigned int depth);
     196             : 
     197             : /**
     198             :  * sbitmap_get() - Try to allocate a free bit from a &struct sbitmap.
     199             :  * @sb: Bitmap to allocate from.
     200             :  *
     201             :  * This operation provides acquire barrier semantics if it succeeds.
     202             :  *
     203             :  * Return: Non-negative allocated bit number if successful, -1 otherwise.
     204             :  */
     205             : int sbitmap_get(struct sbitmap *sb);
     206             : 
     207             : /**
     208             :  * sbitmap_get_shallow() - Try to allocate a free bit from a &struct sbitmap,
     209             :  * limiting the depth used from each word.
     210             :  * @sb: Bitmap to allocate from.
     211             :  * @shallow_depth: The maximum number of bits to allocate from a single word.
     212             :  *
     213             :  * This rather specific operation allows for having multiple users with
     214             :  * different allocation limits. E.g., there can be a high-priority class that
     215             :  * uses sbitmap_get() and a low-priority class that uses sbitmap_get_shallow()
     216             :  * with a @shallow_depth of (1 << (@sb->shift - 1)). Then, the low-priority
     217             :  * class can only allocate half of the total bits in the bitmap, preventing it
     218             :  * from starving out the high-priority class.
     219             :  *
     220             :  * Return: Non-negative allocated bit number if successful, -1 otherwise.
     221             :  */
     222             : int sbitmap_get_shallow(struct sbitmap *sb, unsigned long shallow_depth);
     223             : 
     224             : /**
     225             :  * sbitmap_any_bit_set() - Check for a set bit in a &struct sbitmap.
     226             :  * @sb: Bitmap to check.
     227             :  *
     228             :  * Return: true if any bit in the bitmap is set, false otherwise.
     229             :  */
     230             : bool sbitmap_any_bit_set(const struct sbitmap *sb);
     231             : 
     232             : #define SB_NR_TO_INDEX(sb, bitnr) ((bitnr) >> (sb)->shift)
     233             : #define SB_NR_TO_BIT(sb, bitnr) ((bitnr) & ((1U << (sb)->shift) - 1U))
     234             : 
     235             : typedef bool (*sb_for_each_fn)(struct sbitmap *, unsigned int, void *);
     236             : 
     237             : /**
     238             :  * __sbitmap_for_each_set() - Iterate over each set bit in a &struct sbitmap.
     239             :  * @start: Where to start the iteration.
     240             :  * @sb: Bitmap to iterate over.
     241             :  * @fn: Callback. Should return true to continue or false to break early.
     242             :  * @data: Pointer to pass to callback.
     243             :  *
     244             :  * This is inline even though it's non-trivial so that the function calls to the
     245             :  * callback will hopefully get optimized away.
     246             :  */
     247           0 : static inline void __sbitmap_for_each_set(struct sbitmap *sb,
     248             :                                           unsigned int start,
     249             :                                           sb_for_each_fn fn, void *data)
     250             : {
     251             :         unsigned int index;
     252             :         unsigned int nr;
     253           0 :         unsigned int scanned = 0;
     254             : 
     255           0 :         if (start >= sb->depth)
     256           0 :                 start = 0;
     257           0 :         index = SB_NR_TO_INDEX(sb, start);
     258           0 :         nr = SB_NR_TO_BIT(sb, start);
     259             : 
     260           0 :         while (scanned < sb->depth) {
     261             :                 unsigned long word;
     262           0 :                 unsigned int depth = min_t(unsigned int,
     263             :                                            __map_depth(sb, index) - nr,
     264             :                                            sb->depth - scanned);
     265             : 
     266           0 :                 scanned += depth;
     267           0 :                 word = sb->map[index].word & ~sb->map[index].cleared;
     268           0 :                 if (!word)
     269             :                         goto next;
     270             : 
     271             :                 /*
     272             :                  * On the first iteration of the outer loop, we need to add the
     273             :                  * bit offset back to the size of the word for find_next_bit().
     274             :                  * On all other iterations, nr is zero, so this is a noop.
     275             :                  */
     276           0 :                 depth += nr;
     277             :                 while (1) {
     278           0 :                         nr = find_next_bit(&word, depth, nr);
     279           0 :                         if (nr >= depth)
     280             :                                 break;
     281           0 :                         if (!fn(sb, (index << sb->shift) + nr, data))
     282           0 :                                 return;
     283             : 
     284           0 :                         nr++;
     285             :                 }
     286             : next:
     287           0 :                 nr = 0;
     288           0 :                 if (++index >= sb->map_nr)
     289           0 :                         index = 0;
     290             :         }
     291             : }
     292             : 
     293             : /**
     294             :  * sbitmap_for_each_set() - Iterate over each set bit in a &struct sbitmap.
     295             :  * @sb: Bitmap to iterate over.
     296             :  * @fn: Callback. Should return true to continue or false to break early.
     297             :  * @data: Pointer to pass to callback.
     298             :  */
     299             : static inline void sbitmap_for_each_set(struct sbitmap *sb, sb_for_each_fn fn,
     300             :                                         void *data)
     301             : {
     302           0 :         __sbitmap_for_each_set(sb, 0, fn, data);
     303             : }
     304             : 
     305             : static inline unsigned long *__sbitmap_word(struct sbitmap *sb,
     306             :                                             unsigned int bitnr)
     307             : {
     308           0 :         return &sb->map[SB_NR_TO_INDEX(sb, bitnr)].word;
     309             : }
     310             : 
     311             : /* Helpers equivalent to the operations in asm/bitops.h and linux/bitmap.h */
     312             : 
     313             : static inline void sbitmap_set_bit(struct sbitmap *sb, unsigned int bitnr)
     314             : {
     315           0 :         set_bit(SB_NR_TO_BIT(sb, bitnr), __sbitmap_word(sb, bitnr));
     316             : }
     317             : 
     318             : static inline void sbitmap_clear_bit(struct sbitmap *sb, unsigned int bitnr)
     319             : {
     320           0 :         clear_bit(SB_NR_TO_BIT(sb, bitnr), __sbitmap_word(sb, bitnr));
     321             : }
     322             : 
     323             : /*
     324             :  * This one is special, since it doesn't actually clear the bit, rather it
     325             :  * sets the corresponding bit in the ->cleared mask instead. Paired with
     326             :  * the caller doing sbitmap_deferred_clear() if a given index is full, which
     327             :  * will clear the previously freed entries in the corresponding ->word.
     328             :  */
     329             : static inline void sbitmap_deferred_clear_bit(struct sbitmap *sb, unsigned int bitnr)
     330             : {
     331           0 :         unsigned long *addr = &sb->map[SB_NR_TO_INDEX(sb, bitnr)].cleared;
     332             : 
     333           0 :         set_bit(SB_NR_TO_BIT(sb, bitnr), addr);
     334             : }
     335             : 
     336             : /*
     337             :  * Pair of sbitmap_get, and this one applies both cleared bit and
     338             :  * allocation hint.
     339             :  */
     340             : static inline void sbitmap_put(struct sbitmap *sb, unsigned int bitnr)
     341             : {
     342             :         sbitmap_deferred_clear_bit(sb, bitnr);
     343             : 
     344             :         if (likely(sb->alloc_hint && !sb->round_robin && bitnr < sb->depth))
     345             :                 *raw_cpu_ptr(sb->alloc_hint) = bitnr;
     346             : }
     347             : 
     348             : static inline int sbitmap_test_bit(struct sbitmap *sb, unsigned int bitnr)
     349             : {
     350           0 :         return test_bit(SB_NR_TO_BIT(sb, bitnr), __sbitmap_word(sb, bitnr));
     351             : }
     352             : 
     353             : static inline int sbitmap_calculate_shift(unsigned int depth)
     354             : {
     355           0 :         int     shift = ilog2(BITS_PER_LONG);
     356             : 
     357             :         /*
     358             :          * If the bitmap is small, shrink the number of bits per word so
     359             :          * we spread over a few cachelines, at least. If less than 4
     360             :          * bits, just forget about it, it's not going to work optimally
     361             :          * anyway.
     362             :          */
     363           0 :         if (depth >= 4) {
     364           0 :                 while ((4U << shift) > depth)
     365           0 :                         shift--;
     366             :         }
     367             : 
     368             :         return shift;
     369             : }
     370             : 
     371             : /**
     372             :  * sbitmap_show() - Dump &struct sbitmap information to a &struct seq_file.
     373             :  * @sb: Bitmap to show.
     374             :  * @m: struct seq_file to write to.
     375             :  *
     376             :  * This is intended for debugging. The format may change at any time.
     377             :  */
     378             : void sbitmap_show(struct sbitmap *sb, struct seq_file *m);
     379             : 
     380             : 
     381             : /**
     382             :  * sbitmap_weight() - Return how many set and not cleared bits in a &struct
     383             :  * sbitmap.
     384             :  * @sb: Bitmap to check.
     385             :  *
     386             :  * Return: How many set and not cleared bits set
     387             :  */
     388             : unsigned int sbitmap_weight(const struct sbitmap *sb);
     389             : 
     390             : /**
     391             :  * sbitmap_bitmap_show() - Write a hex dump of a &struct sbitmap to a &struct
     392             :  * seq_file.
     393             :  * @sb: Bitmap to show.
     394             :  * @m: struct seq_file to write to.
     395             :  *
     396             :  * This is intended for debugging. The output isn't guaranteed to be internally
     397             :  * consistent.
     398             :  */
     399             : void sbitmap_bitmap_show(struct sbitmap *sb, struct seq_file *m);
     400             : 
     401             : /**
     402             :  * sbitmap_queue_init_node() - Initialize a &struct sbitmap_queue on a specific
     403             :  * memory node.
     404             :  * @sbq: Bitmap queue to initialize.
     405             :  * @depth: See sbitmap_init_node().
     406             :  * @shift: See sbitmap_init_node().
     407             :  * @round_robin: See sbitmap_get().
     408             :  * @flags: Allocation flags.
     409             :  * @node: Memory node to allocate on.
     410             :  *
     411             :  * Return: Zero on success or negative errno on failure.
     412             :  */
     413             : int sbitmap_queue_init_node(struct sbitmap_queue *sbq, unsigned int depth,
     414             :                             int shift, bool round_robin, gfp_t flags, int node);
     415             : 
     416             : /**
     417             :  * sbitmap_queue_free() - Free memory used by a &struct sbitmap_queue.
     418             :  *
     419             :  * @sbq: Bitmap queue to free.
     420             :  */
     421           0 : static inline void sbitmap_queue_free(struct sbitmap_queue *sbq)
     422             : {
     423           0 :         kfree(sbq->ws);
     424           0 :         sbitmap_free(&sbq->sb);
     425           0 : }
     426             : 
     427             : /**
     428             :  * sbitmap_queue_recalculate_wake_batch() - Recalculate wake batch
     429             :  * @sbq: Bitmap queue to recalculate wake batch.
     430             :  * @users: Number of shares.
     431             :  *
     432             :  * Like sbitmap_queue_update_wake_batch(), this will calculate wake batch
     433             :  * by depth. This interface is for HCTX shared tags or queue shared tags.
     434             :  */
     435             : void sbitmap_queue_recalculate_wake_batch(struct sbitmap_queue *sbq,
     436             :                                             unsigned int users);
     437             : 
     438             : /**
     439             :  * sbitmap_queue_resize() - Resize a &struct sbitmap_queue.
     440             :  * @sbq: Bitmap queue to resize.
     441             :  * @depth: New number of bits to resize to.
     442             :  *
     443             :  * Like sbitmap_resize(), this doesn't reallocate anything. It has to do
     444             :  * some extra work on the &struct sbitmap_queue, so it's not safe to just
     445             :  * resize the underlying &struct sbitmap.
     446             :  */
     447             : void sbitmap_queue_resize(struct sbitmap_queue *sbq, unsigned int depth);
     448             : 
     449             : /**
     450             :  * __sbitmap_queue_get() - Try to allocate a free bit from a &struct
     451             :  * sbitmap_queue with preemption already disabled.
     452             :  * @sbq: Bitmap queue to allocate from.
     453             :  *
     454             :  * Return: Non-negative allocated bit number if successful, -1 otherwise.
     455             :  */
     456             : int __sbitmap_queue_get(struct sbitmap_queue *sbq);
     457             : 
     458             : /**
     459             :  * __sbitmap_queue_get_batch() - Try to allocate a batch of free bits
     460             :  * @sbq: Bitmap queue to allocate from.
     461             :  * @nr_tags: number of tags requested
     462             :  * @offset: offset to add to returned bits
     463             :  *
     464             :  * Return: Mask of allocated tags, 0 if none are found. Each tag allocated is
     465             :  * a bit in the mask returned, and the caller must add @offset to the value to
     466             :  * get the absolute tag value.
     467             :  */
     468             : unsigned long __sbitmap_queue_get_batch(struct sbitmap_queue *sbq, int nr_tags,
     469             :                                         unsigned int *offset);
     470             : 
     471             : /**
     472             :  * sbitmap_queue_get_shallow() - Try to allocate a free bit from a &struct
     473             :  * sbitmap_queue, limiting the depth used from each word, with preemption
     474             :  * already disabled.
     475             :  * @sbq: Bitmap queue to allocate from.
     476             :  * @shallow_depth: The maximum number of bits to allocate from a single word.
     477             :  * See sbitmap_get_shallow().
     478             :  *
     479             :  * If you call this, make sure to call sbitmap_queue_min_shallow_depth() after
     480             :  * initializing @sbq.
     481             :  *
     482             :  * Return: Non-negative allocated bit number if successful, -1 otherwise.
     483             :  */
     484             : int sbitmap_queue_get_shallow(struct sbitmap_queue *sbq,
     485             :                               unsigned int shallow_depth);
     486             : 
     487             : /**
     488             :  * sbitmap_queue_get() - Try to allocate a free bit from a &struct
     489             :  * sbitmap_queue.
     490             :  * @sbq: Bitmap queue to allocate from.
     491             :  * @cpu: Output parameter; will contain the CPU we ran on (e.g., to be passed to
     492             :  *       sbitmap_queue_clear()).
     493             :  *
     494             :  * Return: Non-negative allocated bit number if successful, -1 otherwise.
     495             :  */
     496             : static inline int sbitmap_queue_get(struct sbitmap_queue *sbq,
     497             :                                     unsigned int *cpu)
     498             : {
     499             :         int nr;
     500             : 
     501             :         *cpu = get_cpu();
     502             :         nr = __sbitmap_queue_get(sbq);
     503             :         put_cpu();
     504             :         return nr;
     505             : }
     506             : 
     507             : /**
     508             :  * sbitmap_queue_min_shallow_depth() - Inform a &struct sbitmap_queue of the
     509             :  * minimum shallow depth that will be used.
     510             :  * @sbq: Bitmap queue in question.
     511             :  * @min_shallow_depth: The minimum shallow depth that will be passed to
     512             :  * sbitmap_queue_get_shallow() or __sbitmap_queue_get_shallow().
     513             :  *
     514             :  * sbitmap_queue_clear() batches wakeups as an optimization. The batch size
     515             :  * depends on the depth of the bitmap. Since the shallow allocation functions
     516             :  * effectively operate with a different depth, the shallow depth must be taken
     517             :  * into account when calculating the batch size. This function must be called
     518             :  * with the minimum shallow depth that will be used. Failure to do so can result
     519             :  * in missed wakeups.
     520             :  */
     521             : void sbitmap_queue_min_shallow_depth(struct sbitmap_queue *sbq,
     522             :                                      unsigned int min_shallow_depth);
     523             : 
     524             : /**
     525             :  * sbitmap_queue_clear() - Free an allocated bit and wake up waiters on a
     526             :  * &struct sbitmap_queue.
     527             :  * @sbq: Bitmap to free from.
     528             :  * @nr: Bit number to free.
     529             :  * @cpu: CPU the bit was allocated on.
     530             :  */
     531             : void sbitmap_queue_clear(struct sbitmap_queue *sbq, unsigned int nr,
     532             :                          unsigned int cpu);
     533             : 
     534             : /**
     535             :  * sbitmap_queue_clear_batch() - Free a batch of allocated bits
     536             :  * &struct sbitmap_queue.
     537             :  * @sbq: Bitmap to free from.
     538             :  * @offset: offset for each tag in array
     539             :  * @tags: array of tags
     540             :  * @nr_tags: number of tags in array
     541             :  */
     542             : void sbitmap_queue_clear_batch(struct sbitmap_queue *sbq, int offset,
     543             :                                 int *tags, int nr_tags);
     544             : 
     545             : static inline int sbq_index_inc(int index)
     546             : {
     547           0 :         return (index + 1) & (SBQ_WAIT_QUEUES - 1);
     548             : }
     549             : 
     550             : static inline void sbq_index_atomic_inc(atomic_t *index)
     551             : {
     552           0 :         int old = atomic_read(index);
     553           0 :         int new = sbq_index_inc(old);
     554           0 :         atomic_cmpxchg(index, old, new);
     555             : }
     556             : 
     557             : /**
     558             :  * sbq_wait_ptr() - Get the next wait queue to use for a &struct
     559             :  * sbitmap_queue.
     560             :  * @sbq: Bitmap queue to wait on.
     561             :  * @wait_index: A counter per "user" of @sbq.
     562             :  */
     563             : static inline struct sbq_wait_state *sbq_wait_ptr(struct sbitmap_queue *sbq,
     564             :                                                   atomic_t *wait_index)
     565             : {
     566             :         struct sbq_wait_state *ws;
     567             : 
     568           0 :         ws = &sbq->ws[atomic_read(wait_index)];
     569           0 :         sbq_index_atomic_inc(wait_index);
     570             :         return ws;
     571             : }
     572             : 
     573             : /**
     574             :  * sbitmap_queue_wake_all() - Wake up everything waiting on a &struct
     575             :  * sbitmap_queue.
     576             :  * @sbq: Bitmap queue to wake up.
     577             :  */
     578             : void sbitmap_queue_wake_all(struct sbitmap_queue *sbq);
     579             : 
     580             : /**
     581             :  * sbitmap_queue_wake_up() - Wake up some of waiters in one waitqueue
     582             :  * on a &struct sbitmap_queue.
     583             :  * @sbq: Bitmap queue to wake up.
     584             :  * @nr: Number of bits cleared.
     585             :  */
     586             : void sbitmap_queue_wake_up(struct sbitmap_queue *sbq, int nr);
     587             : 
     588             : /**
     589             :  * sbitmap_queue_show() - Dump &struct sbitmap_queue information to a &struct
     590             :  * seq_file.
     591             :  * @sbq: Bitmap queue to show.
     592             :  * @m: struct seq_file to write to.
     593             :  *
     594             :  * This is intended for debugging. The format may change at any time.
     595             :  */
     596             : void sbitmap_queue_show(struct sbitmap_queue *sbq, struct seq_file *m);
     597             : 
     598             : struct sbq_wait {
     599             :         struct sbitmap_queue *sbq;      /* if set, sbq_wait is accounted */
     600             :         struct wait_queue_entry wait;
     601             : };
     602             : 
     603             : #define DEFINE_SBQ_WAIT(name)                                                   \
     604             :         struct sbq_wait name = {                                                \
     605             :                 .sbq = NULL,                                                    \
     606             :                 .wait = {                                                       \
     607             :                         .private        = current,                              \
     608             :                         .func           = autoremove_wake_function,             \
     609             :                         .entry          = LIST_HEAD_INIT((name).wait.entry),    \
     610             :                 }                                                               \
     611             :         }
     612             : 
     613             : /*
     614             :  * Wrapper around prepare_to_wait_exclusive(), which maintains some extra
     615             :  * internal state.
     616             :  */
     617             : void sbitmap_prepare_to_wait(struct sbitmap_queue *sbq,
     618             :                                 struct sbq_wait_state *ws,
     619             :                                 struct sbq_wait *sbq_wait, int state);
     620             : 
     621             : /*
     622             :  * Must be paired with sbitmap_prepare_to_wait().
     623             :  */
     624             : void sbitmap_finish_wait(struct sbitmap_queue *sbq, struct sbq_wait_state *ws,
     625             :                                 struct sbq_wait *sbq_wait);
     626             : 
     627             : /*
     628             :  * Wrapper around add_wait_queue(), which maintains some extra internal state
     629             :  */
     630             : void sbitmap_add_wait_queue(struct sbitmap_queue *sbq,
     631             :                             struct sbq_wait_state *ws,
     632             :                             struct sbq_wait *sbq_wait);
     633             : 
     634             : /*
     635             :  * Must be paired with sbitmap_add_wait_queue()
     636             :  */
     637             : void sbitmap_del_wait_queue(struct sbq_wait *sbq_wait);
     638             : 
     639             : #endif /* __LINUX_SCALE_BITMAP_H */

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