// SPDX-License-Identifier: GPL-2.0-only
/*
 * Copyright (C) 2016 Facebook
 * Copyright (C) 2013-2014 Jens Axboe
 */

#include <linux/sched.h>
#include <linux/random.h>
#include <linux/sbitmap.h>
#include <linux/seq_file.h>

static int init_alloc_hint(struct sbitmap *sb, gfp_t flags)
{
        unsigned depth = sb->depth;

        sb->alloc_hint = alloc_percpu_gfp(unsigned int, flags);
        if (!sb->alloc_hint)
                return -ENOMEM;

        if (depth && !sb->round_robin) {
                int i;

                for_each_possible_cpu(i)
                        *per_cpu_ptr(sb->alloc_hint, i) = get_random_u32_below(depth);
        }
        return 0;
}

static inline unsigned update_alloc_hint_before_get(struct sbitmap *sb,
                                                    unsigned int depth)
{
        unsigned hint;

        hint = this_cpu_read(*sb->alloc_hint);
        if (unlikely(hint >= depth)) {
                hint = depth ? get_random_u32_below(depth) : 0;
                this_cpu_write(*sb->alloc_hint, hint);
        }

        return hint;
}

static inline void update_alloc_hint_after_get(struct sbitmap *sb,
                                               unsigned int depth,
                                               unsigned int hint,
                                               unsigned int nr)
{
        if (nr == -1) {
                /* If the map is full, a hint won't do us much good. */
                this_cpu_write(*sb->alloc_hint, 0);
        } else if (nr == hint || unlikely(sb->round_robin)) {
                /* Only update the hint if we used it. */
                hint = nr + 1;
                if (hint >= depth - 1)
                        hint = 0;
                this_cpu_write(*sb->alloc_hint, hint);
        }
}

/*
 * See if we have deferred clears that we can batch move
 */
static inline bool sbitmap_deferred_clear(struct sbitmap_word *map,
                unsigned int depth, unsigned int alloc_hint, bool wrap)
{
        unsigned long mask, word_mask;

        guard(raw_spinlock_irqsave)(&map->swap_lock);

        if (!map->cleared) {
                if (depth == 0)
                        return false;

                word_mask = (~0UL) >> (BITS_PER_LONG - depth);
                /*
                 * The current behavior is to always retry after moving
                 * ->cleared to word, and we change it to retry in case
                 * of any free bits. To avoid an infinite loop, we need
                 * to take wrap & alloc_hint into account, otherwise a
                 * soft lockup may occur.
                 */
                if (!wrap && alloc_hint)
                        word_mask &= ~((1UL << alloc_hint) - 1);

                return (READ_ONCE(map->word) & word_mask) != word_mask;
        }

        /*
         * First get a stable cleared mask, setting the old mask to 0.
         */
        mask = xchg(&map->cleared, 0);

        /*
         * Now clear the masked bits in our free word
         */
        atomic_long_andnot(mask, (atomic_long_t *)&map->word);
        BUILD_BUG_ON(sizeof(atomic_long_t) != sizeof(map->word));
        return true;
}

int sbitmap_init_node(struct sbitmap *sb, unsigned int depth, int shift,
                      gfp_t flags, int node, bool round_robin,
                      bool alloc_hint)
{
        unsigned int bits_per_word;
        int i;

        if (shift < 0)
                shift = sbitmap_calculate_shift(depth);

        bits_per_word = 1U << shift;
        if (bits_per_word > BITS_PER_LONG)
                return -EINVAL;

        sb->shift = shift;
        sb->depth = depth;
        sb->map_nr = DIV_ROUND_UP(sb->depth, bits_per_word);
        sb->round_robin = round_robin;

        if (depth == 0) {
                sb->map = NULL;
                return 0;
        }

        if (alloc_hint) {
                if (init_alloc_hint(sb, flags))
                        return -ENOMEM;
        } else {
                sb->alloc_hint = NULL;
        }

        sb->map = kvzalloc_node(sb->map_nr * sizeof(*sb->map), flags, node);
        if (!sb->map) {
                free_percpu(sb->alloc_hint);
                return -ENOMEM;
        }

        for (i = 0; i < sb->map_nr; i++)
                raw_spin_lock_init(&sb->map[i].swap_lock);

        return 0;
}
EXPORT_SYMBOL_GPL(sbitmap_init_node);

void sbitmap_resize(struct sbitmap *sb, unsigned int depth)
{
        unsigned int bits_per_word = 1U << sb->shift;
        unsigned int i;

        for (i = 0; i < sb->map_nr; i++)
                sbitmap_deferred_clear(&sb->map[i], 0, 0, 0);

        sb->depth = depth;
        sb->map_nr = DIV_ROUND_UP(sb->depth, bits_per_word);
}
EXPORT_SYMBOL_GPL(sbitmap_resize);

static int __sbitmap_get_word(unsigned long *word, unsigned long depth,
                              unsigned int hint, bool wrap)
{
        int nr;

        /* don't wrap if starting from 0 */
        wrap = wrap && hint;

        while (1) {
                nr = find_next_zero_bit(word, depth, hint);
                if (unlikely(nr >= depth)) {
                        /*
                         * We started with an offset, and we didn't reset the
                         * offset to 0 in a failure case, so start from 0 to
                         * exhaust the map.
                         */
                        if (hint && wrap) {
                                hint = 0;
                                continue;
                        }
                        return -1;
                }

                if (!test_and_set_bit_lock(nr, word))
                        break;

                hint = nr + 1;
                if (hint >= depth - 1)
                        hint = 0;
        }

        return nr;
}

static int sbitmap_find_bit_in_word(struct sbitmap_word *map,
                                    unsigned int depth,
                                    unsigned int alloc_hint,
                                    bool wrap)
{
        int nr;

        do {
                nr = __sbitmap_get_word(&map->word, depth,
                                        alloc_hint, wrap);
                if (nr != -1)
                        break;
                if (!sbitmap_deferred_clear(map, depth, alloc_hint, wrap))
                        break;
        } while (1);

        return nr;
}

static unsigned int __map_depth_with_shallow(const struct sbitmap *sb,
                                             int index,
                                             unsigned int shallow_depth)
{
        u64 shallow_word_depth;
        unsigned int word_depth, reminder;

        word_depth = __map_depth(sb, index);
        if (shallow_depth >= sb->depth)
                return word_depth;

        shallow_word_depth = word_depth * shallow_depth;
        reminder = do_div(shallow_word_depth, sb->depth);

        if (reminder >= (index + 1) * word_depth)
                shallow_word_depth++;

        return (unsigned int)shallow_word_depth;
}

static int sbitmap_find_bit(struct sbitmap *sb,
                            unsigned int shallow_depth,
                            unsigned int index,
                            unsigned int alloc_hint,
                            bool wrap)
{
        unsigned int i;
        int nr = -1;

        for (i = 0; i < sb->map_nr; i++) {
                unsigned int depth = __map_depth_with_shallow(sb, index,
                                                              shallow_depth);

                if (depth)
                        nr = sbitmap_find_bit_in_word(&sb->map[index], depth,
                                                      alloc_hint, wrap);
                if (nr != -1) {
                        nr += index << sb->shift;
                        break;
                }

                /* Jump to next index. */
                alloc_hint = 0;
                if (++index >= sb->map_nr)
                        index = 0;
        }

        return nr;
}

static int __sbitmap_get(struct sbitmap *sb, unsigned int alloc_hint)
{
        unsigned int index;

        index = SB_NR_TO_INDEX(sb, alloc_hint);

        /*
         * Unless we're doing round robin tag allocation, just use the
         * alloc_hint to find the right word index. No point in looping
         * twice in find_next_zero_bit() for that case.
         */
        if (sb->round_robin)
                alloc_hint = SB_NR_TO_BIT(sb, alloc_hint);
        else
                alloc_hint = 0;

        return sbitmap_find_bit(sb, UINT_MAX, index, alloc_hint,
                                !sb->round_robin);
}

int sbitmap_get(struct sbitmap *sb)
{
        int nr;
        unsigned int hint, depth;

        if (WARN_ON_ONCE(unlikely(!sb->alloc_hint)))
                return -1;

        depth = READ_ONCE(sb->depth);
        hint = update_alloc_hint_before_get(sb, depth);
        nr = __sbitmap_get(sb, hint);
        update_alloc_hint_after_get(sb, depth, hint, nr);

        return nr;
}
EXPORT_SYMBOL_GPL(sbitmap_get);

static int __sbitmap_get_shallow(struct sbitmap *sb,
                                 unsigned int alloc_hint,
                                 unsigned long shallow_depth)
{
        unsigned int index;

        index = SB_NR_TO_INDEX(sb, alloc_hint);
        alloc_hint = SB_NR_TO_BIT(sb, alloc_hint);

        return sbitmap_find_bit(sb, shallow_depth, index, alloc_hint, true);
}

/**
 * sbitmap_get_shallow() - Try to allocate a free bit from a &struct sbitmap,
 * limiting the depth used from each word.
 * @sb: Bitmap to allocate from.
 * @shallow_depth: The maximum number of bits to allocate from the bitmap.
 *
 * This rather specific operation allows for having multiple users with
 * different allocation limits. E.g., there can be a high-priority class that
 * uses sbitmap_get() and a low-priority class that uses sbitmap_get_shallow()
 * with a @shallow_depth of (sb->depth >> 1). Then, the low-priority
 * class can only allocate half of the total bits in the bitmap, preventing it
 * from starving out the high-priority class.
 *
 * Return: Non-negative allocated bit number if successful, -1 otherwise.
 */
static int sbitmap_get_shallow(struct sbitmap *sb, unsigned long shallow_depth)
{
        int nr;
        unsigned int hint, depth;

        if (WARN_ON_ONCE(unlikely(!sb->alloc_hint)))
                return -1;

        depth = READ_ONCE(sb->depth);
        hint = update_alloc_hint_before_get(sb, depth);
        nr = __sbitmap_get_shallow(sb, hint, shallow_depth);
        update_alloc_hint_after_get(sb, depth, hint, nr);

        return nr;
}

bool sbitmap_any_bit_set(const struct sbitmap *sb)
{
        unsigned int i;

        for (i = 0; i < sb->map_nr; i++) {
                if (sb->map[i].word & ~sb->map[i].cleared)
                        return true;
        }
        return false;
}
EXPORT_SYMBOL_GPL(sbitmap_any_bit_set);

static unsigned int __sbitmap_weight(const struct sbitmap *sb, bool set)
{
        unsigned int i, weight = 0;

        for (i = 0; i < sb->map_nr; i++) {
                const struct sbitmap_word *word = &sb->map[i];
                unsigned int word_depth = __map_depth(sb, i);

                if (set)
                        weight += bitmap_weight(&word->word, word_depth);
                else
                        weight += bitmap_weight(&word->cleared, word_depth);
        }
        return weight;
}

static unsigned int sbitmap_cleared(const struct sbitmap *sb)
{
        return __sbitmap_weight(sb, false);
}

unsigned int sbitmap_weight(const struct sbitmap *sb)
{
        return __sbitmap_weight(sb, true) - sbitmap_cleared(sb);
}
EXPORT_SYMBOL_GPL(sbitmap_weight);

void sbitmap_show(struct sbitmap *sb, struct seq_file *m)
{
        seq_printf(m, "depth=%u\n", sb->depth);
        seq_printf(m, "busy=%u\n", sbitmap_weight(sb));
        seq_printf(m, "cleared=%u\n", sbitmap_cleared(sb));
        seq_printf(m, "bits_per_word=%u\n", 1U << sb->shift);
        seq_printf(m, "map_nr=%u\n", sb->map_nr);
}
EXPORT_SYMBOL_GPL(sbitmap_show);

static inline void emit_byte(struct seq_file *m, unsigned int offset, u8 byte)
{
        if ((offset & 0xf) == 0) {
                if (offset != 0)
                        seq_putc(m, '\n');
                seq_printf(m, "%08x:", offset);
        }
        if ((offset & 0x1) == 0)
                seq_putc(m, ' ');
        seq_printf(m, "%02x", byte);
}

void sbitmap_bitmap_show(struct sbitmap *sb, struct seq_file *m)
{
        u8 byte = 0;
        unsigned int byte_bits = 0;
        unsigned int offset = 0;
        int i;

        for (i = 0; i < sb->map_nr; i++) {
                unsigned long word = READ_ONCE(sb->map[i].word);
                unsigned long cleared = READ_ONCE(sb->map[i].cleared);
                unsigned int word_bits = __map_depth(sb, i);

                word &= ~cleared;

                while (word_bits > 0) {
                        unsigned int bits = min(8 - byte_bits, word_bits);

                        byte |= (word & (BIT(bits) - 1)) << byte_bits;
                        byte_bits += bits;
                        if (byte_bits == 8) {
                                emit_byte(m, offset, byte);
                                byte = 0;
                                byte_bits = 0;
                                offset++;
                        }
                        word >>= bits;
                        word_bits -= bits;
                }
        }
        if (byte_bits) {
                emit_byte(m, offset, byte);
                offset++;
        }
        if (offset)
                seq_putc(m, '\n');
}
EXPORT_SYMBOL_GPL(sbitmap_bitmap_show);

static unsigned int sbq_calc_wake_batch(struct sbitmap_queue *sbq,
                                        unsigned int depth)
{
        return clamp_t(unsigned int,
                       min(depth, sbq->min_shallow_depth) / SBQ_WAIT_QUEUES,
                       1, SBQ_WAKE_BATCH);
}

int sbitmap_queue_init_node(struct sbitmap_queue *sbq, unsigned int depth,
                            int shift, bool round_robin, gfp_t flags, int node)
{
        int ret;
        int i;

        ret = sbitmap_init_node(&sbq->sb, depth, shift, flags, node,
                                round_robin, true);
        if (ret)
                return ret;

        sbq->min_shallow_depth = UINT_MAX;
        sbq->wake_batch = sbq_calc_wake_batch(sbq, depth);
        atomic_set(&sbq->wake_index, 0);
        atomic_set(&sbq->ws_active, 0);
        atomic_set(&sbq->completion_cnt, 0);
        atomic_set(&sbq->wakeup_cnt, 0);

        sbq->ws = kzalloc_node(SBQ_WAIT_QUEUES * sizeof(*sbq->ws), flags, node);
        if (!sbq->ws) {
                sbitmap_free(&sbq->sb);
                return -ENOMEM;
        }

        for (i = 0; i < SBQ_WAIT_QUEUES; i++)
                init_waitqueue_head(&sbq->ws[i].wait);

        return 0;
}
EXPORT_SYMBOL_GPL(sbitmap_queue_init_node);

static void sbitmap_queue_update_wake_batch(struct sbitmap_queue *sbq,
                                            unsigned int depth)
{
        unsigned int wake_batch;

        wake_batch = sbq_calc_wake_batch(sbq, depth);
        if (sbq->wake_batch != wake_batch)
                WRITE_ONCE(sbq->wake_batch, wake_batch);
}

void sbitmap_queue_recalculate_wake_batch(struct sbitmap_queue *sbq,
                                            unsigned int users)
{
        unsigned int wake_batch;
        unsigned int depth = (sbq->sb.depth + users - 1) / users;

        wake_batch = clamp_val(depth / SBQ_WAIT_QUEUES,
                        1, SBQ_WAKE_BATCH);

        WRITE_ONCE(sbq->wake_batch, wake_batch);
}
EXPORT_SYMBOL_GPL(sbitmap_queue_recalculate_wake_batch);

void sbitmap_queue_resize(struct sbitmap_queue *sbq, unsigned int depth)
{
        sbitmap_queue_update_wake_batch(sbq, depth);
        sbitmap_resize(&sbq->sb, depth);
}
EXPORT_SYMBOL_GPL(sbitmap_queue_resize);

int __sbitmap_queue_get(struct sbitmap_queue *sbq)
{
        return sbitmap_get(&sbq->sb);
}
EXPORT_SYMBOL_GPL(__sbitmap_queue_get);

unsigned long __sbitmap_queue_get_batch(struct sbitmap_queue *sbq, int nr_tags,
                                        unsigned int *offset)
{
        struct sbitmap *sb = &sbq->sb;
        unsigned int hint, depth;
        unsigned long index, nr;
        int i;

        if (unlikely(sb->round_robin))
                return 0;

        depth = READ_ONCE(sb->depth);
        hint = update_alloc_hint_before_get(sb, depth);

        index = SB_NR_TO_INDEX(sb, hint);

        for (i = 0; i < sb->map_nr; i++) {
                struct sbitmap_word *map = &sb->map[index];
                unsigned long get_mask;
                unsigned int map_depth = __map_depth(sb, index);
                unsigned long val;

                sbitmap_deferred_clear(map, 0, 0, 0);
                val = READ_ONCE(map->word);
                if (val == (1UL << (map_depth - 1)) - 1)
                        goto next;

                nr = find_first_zero_bit(&val, map_depth);
                if (nr + nr_tags <= map_depth) {
                        atomic_long_t *ptr = (atomic_long_t *) &map->word;

                        get_mask = ((1UL << nr_tags) - 1) << nr;
                        while (!atomic_long_try_cmpxchg(ptr, &val,
                                                          get_mask | val))
                                ;
                        get_mask = (get_mask & ~val) >> nr;
                        if (get_mask) {
                                *offset = nr + (index << sb->shift);
                                update_alloc_hint_after_get(sb, depth, hint,
                                                        *offset + nr_tags - 1);
                                return get_mask;
                        }
                }
next:
                /* Jump to next index. */
                if (++index >= sb->map_nr)
                        index = 0;
        }

        return 0;
}

int sbitmap_queue_get_shallow(struct sbitmap_queue *sbq,
                              unsigned int shallow_depth)
{
        WARN_ON_ONCE(shallow_depth < sbq->min_shallow_depth);

        return sbitmap_get_shallow(&sbq->sb, shallow_depth);
}
EXPORT_SYMBOL_GPL(sbitmap_queue_get_shallow);

void sbitmap_queue_min_shallow_depth(struct sbitmap_queue *sbq,
                                     unsigned int min_shallow_depth)
{
        sbq->min_shallow_depth = min_shallow_depth;
        sbitmap_queue_update_wake_batch(sbq, sbq->sb.depth);
}
EXPORT_SYMBOL_GPL(sbitmap_queue_min_shallow_depth);

static void __sbitmap_queue_wake_up(struct sbitmap_queue *sbq, int nr)
{
        int i, wake_index, woken;

        if (!atomic_read(&sbq->ws_active))
                return;

        wake_index = atomic_read(&sbq->wake_index);
        for (i = 0; i < SBQ_WAIT_QUEUES; i++) {
                struct sbq_wait_state *ws = &sbq->ws[wake_index];

                /*
                 * Advance the index before checking the current queue.
                 * It improves fairness, by ensuring the queue doesn't
                 * need to be fully emptied before trying to wake up
                 * from the next one.
                 */
                wake_index = sbq_index_inc(wake_index);

                if (waitqueue_active(&ws->wait)) {
                        woken = wake_up_nr(&ws->wait, nr);
                        if (woken == nr)
                                break;
                        nr -= woken;
                }
        }

        if (wake_index != atomic_read(&sbq->wake_index))
                atomic_set(&sbq->wake_index, wake_index);
}

void sbitmap_queue_wake_up(struct sbitmap_queue *sbq, int nr)
{
        unsigned int wake_batch = READ_ONCE(sbq->wake_batch);
        unsigned int wakeups;

        if (!atomic_read(&sbq->ws_active))
                return;

        atomic_add(nr, &sbq->completion_cnt);
        wakeups = atomic_read(&sbq->wakeup_cnt);

        do {
                if (atomic_read(&sbq->completion_cnt) - wakeups < wake_batch)
                        return;
        } while (!atomic_try_cmpxchg(&sbq->wakeup_cnt,
                                     &wakeups, wakeups + wake_batch));

        __sbitmap_queue_wake_up(sbq, wake_batch);
}
EXPORT_SYMBOL_GPL(sbitmap_queue_wake_up);

static inline void sbitmap_update_cpu_hint(struct sbitmap *sb, int cpu, int tag)
{
        if (likely(!sb->round_robin && tag < sb->depth))
                data_race(*per_cpu_ptr(sb->alloc_hint, cpu) = tag);
}

void sbitmap_queue_clear_batch(struct sbitmap_queue *sbq, int offset,
                                int *tags, int nr_tags)
{
        struct sbitmap *sb = &sbq->sb;
        unsigned long *addr = NULL;
        unsigned long mask = 0;
        int i;

        smp_mb__before_atomic();
        for (i = 0; i < nr_tags; i++) {
                const int tag = tags[i] - offset;
                unsigned long *this_addr;

                /* since we're clearing a batch, skip the deferred map */
                this_addr = &sb->map[SB_NR_TO_INDEX(sb, tag)].word;
                if (!addr) {
                        addr = this_addr;
                } else if (addr != this_addr) {
                        atomic_long_andnot(mask, (atomic_long_t *) addr);
                        mask = 0;
                        addr = this_addr;
                }
                mask |= (1UL << SB_NR_TO_BIT(sb, tag));
        }

        if (mask)
                atomic_long_andnot(mask, (atomic_long_t *) addr);

        smp_mb__after_atomic();
        sbitmap_queue_wake_up(sbq, nr_tags);
        sbitmap_update_cpu_hint(&sbq->sb, raw_smp_processor_id(),
                                        tags[nr_tags - 1] - offset);
}

void sbitmap_queue_clear(struct sbitmap_queue *sbq, unsigned int nr,
                         unsigned int cpu)
{
        /*
         * Once the clear bit is set, the bit may be allocated out.
         *
         * Orders READ/WRITE on the associated instance(such as request
         * of blk_mq) by this bit for avoiding race with re-allocation,
         * and its pair is the memory barrier implied in __sbitmap_get_word.
         *
         * One invariant is that the clear bit has to be zero when the bit
         * is in use.
         */
        smp_mb__before_atomic();
        sbitmap_deferred_clear_bit(&sbq->sb, nr);

        /*
         * Pairs with the memory barrier in set_current_state() to ensure the
         * proper ordering of clear_bit_unlock()/waitqueue_active() in the waker
         * and test_and_set_bit_lock()/prepare_to_wait()/finish_wait() in the
         * waiter. See the comment on waitqueue_active().
         */
        smp_mb__after_atomic();
        sbitmap_queue_wake_up(sbq, 1);
        sbitmap_update_cpu_hint(&sbq->sb, cpu, nr);
}
EXPORT_SYMBOL_GPL(sbitmap_queue_clear);

void sbitmap_queue_wake_all(struct sbitmap_queue *sbq)
{
        int i, wake_index;

        /*
         * Pairs with the memory barrier in set_current_state() like in
         * sbitmap_queue_wake_up().
         */
        smp_mb();
        wake_index = atomic_read(&sbq->wake_index);
        for (i = 0; i < SBQ_WAIT_QUEUES; i++) {
                struct sbq_wait_state *ws = &sbq->ws[wake_index];

                if (waitqueue_active(&ws->wait))
                        wake_up(&ws->wait);

                wake_index = sbq_index_inc(wake_index);
        }
}
EXPORT_SYMBOL_GPL(sbitmap_queue_wake_all);

void sbitmap_queue_show(struct sbitmap_queue *sbq, struct seq_file *m)
{
        bool first;
        int i;

        sbitmap_show(&sbq->sb, m);

        seq_puts(m, "alloc_hint={");
        first = true;
        for_each_possible_cpu(i) {
                if (!first)
                        seq_puts(m, ", ");
                first = false;
                seq_printf(m, "%u", *per_cpu_ptr(sbq->sb.alloc_hint, i));
        }
        seq_puts(m, "}\n");

        seq_printf(m, "wake_batch=%u\n", sbq->wake_batch);
        seq_printf(m, "wake_index=%d\n", atomic_read(&sbq->wake_index));
        seq_printf(m, "ws_active=%d\n", atomic_read(&sbq->ws_active));

        seq_puts(m, "ws={\n");
        for (i = 0; i < SBQ_WAIT_QUEUES; i++) {
                struct sbq_wait_state *ws = &sbq->ws[i];
                seq_printf(m, "\t{.wait=%s},\n",
                           waitqueue_active(&ws->wait) ? "active" : "inactive");
        }
        seq_puts(m, "}\n");

        seq_printf(m, "round_robin=%d\n", sbq->sb.round_robin);
        seq_printf(m, "min_shallow_depth=%u\n", sbq->min_shallow_depth);
}
EXPORT_SYMBOL_GPL(sbitmap_queue_show);

void sbitmap_add_wait_queue(struct sbitmap_queue *sbq,
                            struct sbq_wait_state *ws,
                            struct sbq_wait *sbq_wait)
{
        if (!sbq_wait->sbq) {
                sbq_wait->sbq = sbq;
                atomic_inc(&sbq->ws_active);
                add_wait_queue(&ws->wait, &sbq_wait->wait);
        }
}
EXPORT_SYMBOL_GPL(sbitmap_add_wait_queue);

void sbitmap_del_wait_queue(struct sbq_wait *sbq_wait)
{
        list_del_init(&sbq_wait->wait.entry);
        if (sbq_wait->sbq) {
                atomic_dec(&sbq_wait->sbq->ws_active);
                sbq_wait->sbq = NULL;
        }
}
EXPORT_SYMBOL_GPL(sbitmap_del_wait_queue);

void sbitmap_prepare_to_wait(struct sbitmap_queue *sbq,
                             struct sbq_wait_state *ws,
                             struct sbq_wait *sbq_wait, int state)
{
        if (!sbq_wait->sbq) {
                atomic_inc(&sbq->ws_active);
                sbq_wait->sbq = sbq;
        }
        prepare_to_wait_exclusive(&ws->wait, &sbq_wait->wait, state);
}
EXPORT_SYMBOL_GPL(sbitmap_prepare_to_wait);

void sbitmap_finish_wait(struct sbitmap_queue *sbq, struct sbq_wait_state *ws,
                         struct sbq_wait *sbq_wait)
{
        finish_wait(&ws->wait, &sbq_wait->wait);
        if (sbq_wait->sbq) {
                atomic_dec(&sbq->ws_active);
                sbq_wait->sbq = NULL;
        }
}
EXPORT_SYMBOL_GPL(sbitmap_finish_wait);