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diff --git a/include/linux/sbitmap.h b/include/linux/sbitmap.h
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+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Fast and scalable bitmaps.
+ *
+ * Copyright (C) 2016 Facebook
+ * Copyright (C) 2013-2014 Jens Axboe
+ */
+
+#ifndef __LINUX_SCALE_BITMAP_H
+#define __LINUX_SCALE_BITMAP_H
+
+#include <linux/atomic.h>
+#include <linux/bitops.h>
+#include <linux/cache.h>
+#include <linux/list.h>
+#include <linux/log2.h>
+#include <linux/minmax.h>
+#include <linux/percpu.h>
+#include <linux/slab.h>
+#include <linux/smp.h>
+#include <linux/types.h>
+#include <linux/wait.h>
+
+struct seq_file;
+
+/**
+ * struct sbitmap_word - Word in a &struct sbitmap.
+ */
+struct sbitmap_word {
+ /**
+ * @word: word holding free bits
+ */
+ unsigned long word;
+
+ /**
+ * @cleared: word holding cleared bits
+ */
+ unsigned long cleared ____cacheline_aligned_in_smp;
+} ____cacheline_aligned_in_smp;
+
+/**
+ * struct sbitmap - Scalable bitmap.
+ *
+ * A &struct sbitmap is spread over multiple cachelines to avoid ping-pong. This
+ * trades off higher memory usage for better scalability.
+ */
+struct sbitmap {
+ /**
+ * @depth: Number of bits used in the whole bitmap.
+ */
+ unsigned int depth;
+
+ /**
+ * @shift: log2(number of bits used per word)
+ */
+ unsigned int shift;
+
+ /**
+ * @map_nr: Number of words (cachelines) being used for the bitmap.
+ */
+ unsigned int map_nr;
+
+ /**
+ * @round_robin: Allocate bits in strict round-robin order.
+ */
+ bool round_robin;
+
+ /**
+ * @map: Allocated bitmap.
+ */
+ struct sbitmap_word *map;
+
+ /*
+ * @alloc_hint: Cache of last successfully allocated or freed bit.
+ *
+ * This is per-cpu, which allows multiple users to stick to different
+ * cachelines until the map is exhausted.
+ */
+ unsigned int __percpu *alloc_hint;
+};
+
+#define SBQ_WAIT_QUEUES 8
+#define SBQ_WAKE_BATCH 8
+
+/**
+ * struct sbq_wait_state - Wait queue in a &struct sbitmap_queue.
+ */
+struct sbq_wait_state {
+ /**
+ * @wait: Wait queue.
+ */
+ wait_queue_head_t wait;
+} ____cacheline_aligned_in_smp;
+
+/**
+ * struct sbitmap_queue - Scalable bitmap with the added ability to wait on free
+ * bits.
+ *
+ * A &struct sbitmap_queue uses multiple wait queues and rolling wakeups to
+ * avoid contention on the wait queue spinlock. This ensures that we don't hit a
+ * scalability wall when we run out of free bits and have to start putting tasks
+ * to sleep.
+ */
+struct sbitmap_queue {
+ /**
+ * @sb: Scalable bitmap.
+ */
+ struct sbitmap sb;
+
+ /**
+ * @wake_batch: Number of bits which must be freed before we wake up any
+ * waiters.
+ */
+ unsigned int wake_batch;
+
+ /**
+ * @wake_index: Next wait queue in @ws to wake up.
+ */
+ atomic_t wake_index;
+
+ /**
+ * @ws: Wait queues.
+ */
+ struct sbq_wait_state *ws;
+
+ /*
+ * @ws_active: count of currently active ws waitqueues
+ */
+ atomic_t ws_active;
+
+ /**
+ * @min_shallow_depth: The minimum shallow depth which may be passed to
+ * sbitmap_queue_get_shallow()
+ */
+ unsigned int min_shallow_depth;
+
+ /**
+ * @completion_cnt: Number of bits cleared passed to the
+ * wakeup function.
+ */
+ atomic_t completion_cnt;
+
+ /**
+ * @wakeup_cnt: Number of thread wake ups issued.
+ */
+ atomic_t wakeup_cnt;
+};
+
+/**
+ * sbitmap_init_node() - Initialize a &struct sbitmap on a specific memory node.
+ * @sb: Bitmap to initialize.
+ * @depth: Number of bits to allocate.
+ * @shift: Use 2^@shift bits per word in the bitmap; if a negative number if
+ * given, a good default is chosen.
+ * @flags: Allocation flags.
+ * @node: Memory node to allocate on.
+ * @round_robin: If true, be stricter about allocation order; always allocate
+ * starting from the last allocated bit. This is less efficient
+ * than the default behavior (false).
+ * @alloc_hint: If true, apply percpu hint for where to start searching for
+ * a free bit.
+ *
+ * Return: Zero on success or negative errno on failure.
+ */
+int sbitmap_init_node(struct sbitmap *sb, unsigned int depth, int shift,
+ gfp_t flags, int node, bool round_robin, bool alloc_hint);
+
+/* sbitmap internal helper */
+static inline unsigned int __map_depth(const struct sbitmap *sb, int index)
+{
+ if (index == sb->map_nr - 1)
+ return sb->depth - (index << sb->shift);
+ return 1U << sb->shift;
+}
+
+/**
+ * sbitmap_free() - Free memory used by a &struct sbitmap.
+ * @sb: Bitmap to free.
+ */
+static inline void sbitmap_free(struct sbitmap *sb)
+{
+ free_percpu(sb->alloc_hint);
+ kvfree(sb->map);
+ sb->map = NULL;
+}
+
+/**
+ * sbitmap_resize() - Resize a &struct sbitmap.
+ * @sb: Bitmap to resize.
+ * @depth: New number of bits to resize to.
+ *
+ * Doesn't reallocate anything. It's up to the caller to ensure that the new
+ * depth doesn't exceed the depth that the sb was initialized with.
+ */
+void sbitmap_resize(struct sbitmap *sb, unsigned int depth);
+
+/**
+ * sbitmap_get() - Try to allocate a free bit from a &struct sbitmap.
+ * @sb: Bitmap to allocate from.
+ *
+ * This operation provides acquire barrier semantics if it succeeds.
+ *
+ * Return: Non-negative allocated bit number if successful, -1 otherwise.
+ */
+int sbitmap_get(struct sbitmap *sb);
+
+/**
+ * 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 a single word.
+ *
+ * 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 (1 << (@sb->shift - 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.
+ */
+int sbitmap_get_shallow(struct sbitmap *sb, unsigned long shallow_depth);
+
+/**
+ * sbitmap_any_bit_set() - Check for a set bit in a &struct sbitmap.
+ * @sb: Bitmap to check.
+ *
+ * Return: true if any bit in the bitmap is set, false otherwise.
+ */
+bool sbitmap_any_bit_set(const struct sbitmap *sb);
+
+#define SB_NR_TO_INDEX(sb, bitnr) ((bitnr) >> (sb)->shift)
+#define SB_NR_TO_BIT(sb, bitnr) ((bitnr) & ((1U << (sb)->shift) - 1U))
+
+typedef bool (*sb_for_each_fn)(struct sbitmap *, unsigned int, void *);
+
+/**
+ * __sbitmap_for_each_set() - Iterate over each set bit in a &struct sbitmap.
+ * @start: Where to start the iteration.
+ * @sb: Bitmap to iterate over.
+ * @fn: Callback. Should return true to continue or false to break early.
+ * @data: Pointer to pass to callback.
+ *
+ * This is inline even though it's non-trivial so that the function calls to the
+ * callback will hopefully get optimized away.
+ */
+static inline void __sbitmap_for_each_set(struct sbitmap *sb,
+ unsigned int start,
+ sb_for_each_fn fn, void *data)
+{
+ unsigned int index;
+ unsigned int nr;
+ unsigned int scanned = 0;
+
+ if (start >= sb->depth)
+ start = 0;
+ index = SB_NR_TO_INDEX(sb, start);
+ nr = SB_NR_TO_BIT(sb, start);
+
+ while (scanned < sb->depth) {
+ unsigned long word;
+ unsigned int depth = min_t(unsigned int,
+ __map_depth(sb, index) - nr,
+ sb->depth - scanned);
+
+ scanned += depth;
+ word = sb->map[index].word & ~sb->map[index].cleared;
+ if (!word)
+ goto next;
+
+ /*
+ * On the first iteration of the outer loop, we need to add the
+ * bit offset back to the size of the word for find_next_bit().
+ * On all other iterations, nr is zero, so this is a noop.
+ */
+ depth += nr;
+ while (1) {
+ nr = find_next_bit(&word, depth, nr);
+ if (nr >= depth)
+ break;
+ if (!fn(sb, (index << sb->shift) + nr, data))
+ return;
+
+ nr++;
+ }
+next:
+ nr = 0;
+ if (++index >= sb->map_nr)
+ index = 0;
+ }
+}
+
+/**
+ * sbitmap_for_each_set() - Iterate over each set bit in a &struct sbitmap.
+ * @sb: Bitmap to iterate over.
+ * @fn: Callback. Should return true to continue or false to break early.
+ * @data: Pointer to pass to callback.
+ */
+static inline void sbitmap_for_each_set(struct sbitmap *sb, sb_for_each_fn fn,
+ void *data)
+{
+ __sbitmap_for_each_set(sb, 0, fn, data);
+}
+
+static inline unsigned long *__sbitmap_word(struct sbitmap *sb,
+ unsigned int bitnr)
+{
+ return &sb->map[SB_NR_TO_INDEX(sb, bitnr)].word;
+}
+
+/* Helpers equivalent to the operations in asm/bitops.h and linux/bitmap.h */
+
+static inline void sbitmap_set_bit(struct sbitmap *sb, unsigned int bitnr)
+{
+ set_bit(SB_NR_TO_BIT(sb, bitnr), __sbitmap_word(sb, bitnr));
+}
+
+static inline void sbitmap_clear_bit(struct sbitmap *sb, unsigned int bitnr)
+{
+ clear_bit(SB_NR_TO_BIT(sb, bitnr), __sbitmap_word(sb, bitnr));
+}
+
+/*
+ * This one is special, since it doesn't actually clear the bit, rather it
+ * sets the corresponding bit in the ->cleared mask instead. Paired with
+ * the caller doing sbitmap_deferred_clear() if a given index is full, which
+ * will clear the previously freed entries in the corresponding ->word.
+ */
+static inline void sbitmap_deferred_clear_bit(struct sbitmap *sb, unsigned int bitnr)
+{
+ unsigned long *addr = &sb->map[SB_NR_TO_INDEX(sb, bitnr)].cleared;
+
+ set_bit(SB_NR_TO_BIT(sb, bitnr), addr);
+}
+
+/*
+ * Pair of sbitmap_get, and this one applies both cleared bit and
+ * allocation hint.
+ */
+static inline void sbitmap_put(struct sbitmap *sb, unsigned int bitnr)
+{
+ sbitmap_deferred_clear_bit(sb, bitnr);
+
+ if (likely(sb->alloc_hint && !sb->round_robin && bitnr < sb->depth))
+ *raw_cpu_ptr(sb->alloc_hint) = bitnr;
+}
+
+static inline int sbitmap_test_bit(struct sbitmap *sb, unsigned int bitnr)
+{
+ return test_bit(SB_NR_TO_BIT(sb, bitnr), __sbitmap_word(sb, bitnr));
+}
+
+static inline int sbitmap_calculate_shift(unsigned int depth)
+{
+ int shift = ilog2(BITS_PER_LONG);
+
+ /*
+ * If the bitmap is small, shrink the number of bits per word so
+ * we spread over a few cachelines, at least. If less than 4
+ * bits, just forget about it, it's not going to work optimally
+ * anyway.
+ */
+ if (depth >= 4) {
+ while ((4U << shift) > depth)
+ shift--;
+ }
+
+ return shift;
+}
+
+/**
+ * sbitmap_show() - Dump &struct sbitmap information to a &struct seq_file.
+ * @sb: Bitmap to show.
+ * @m: struct seq_file to write to.
+ *
+ * This is intended for debugging. The format may change at any time.
+ */
+void sbitmap_show(struct sbitmap *sb, struct seq_file *m);
+
+
+/**
+ * sbitmap_weight() - Return how many set and not cleared bits in a &struct
+ * sbitmap.
+ * @sb: Bitmap to check.
+ *
+ * Return: How many set and not cleared bits set
+ */
+unsigned int sbitmap_weight(const struct sbitmap *sb);
+
+/**
+ * sbitmap_bitmap_show() - Write a hex dump of a &struct sbitmap to a &struct
+ * seq_file.
+ * @sb: Bitmap to show.
+ * @m: struct seq_file to write to.
+ *
+ * This is intended for debugging. The output isn't guaranteed to be internally
+ * consistent.
+ */
+void sbitmap_bitmap_show(struct sbitmap *sb, struct seq_file *m);
+
+/**
+ * sbitmap_queue_init_node() - Initialize a &struct sbitmap_queue on a specific
+ * memory node.
+ * @sbq: Bitmap queue to initialize.
+ * @depth: See sbitmap_init_node().
+ * @shift: See sbitmap_init_node().
+ * @round_robin: See sbitmap_get().
+ * @flags: Allocation flags.
+ * @node: Memory node to allocate on.
+ *
+ * Return: Zero on success or negative errno on failure.
+ */
+int sbitmap_queue_init_node(struct sbitmap_queue *sbq, unsigned int depth,
+ int shift, bool round_robin, gfp_t flags, int node);
+
+/**
+ * sbitmap_queue_free() - Free memory used by a &struct sbitmap_queue.
+ *
+ * @sbq: Bitmap queue to free.
+ */
+static inline void sbitmap_queue_free(struct sbitmap_queue *sbq)
+{
+ kfree(sbq->ws);
+ sbitmap_free(&sbq->sb);
+}
+
+/**
+ * sbitmap_queue_recalculate_wake_batch() - Recalculate wake batch
+ * @sbq: Bitmap queue to recalculate wake batch.
+ * @users: Number of shares.
+ *
+ * Like sbitmap_queue_update_wake_batch(), this will calculate wake batch
+ * by depth. This interface is for HCTX shared tags or queue shared tags.
+ */
+void sbitmap_queue_recalculate_wake_batch(struct sbitmap_queue *sbq,
+ unsigned int users);
+
+/**
+ * sbitmap_queue_resize() - Resize a &struct sbitmap_queue.
+ * @sbq: Bitmap queue to resize.
+ * @depth: New number of bits to resize to.
+ *
+ * Like sbitmap_resize(), this doesn't reallocate anything. It has to do
+ * some extra work on the &struct sbitmap_queue, so it's not safe to just
+ * resize the underlying &struct sbitmap.
+ */
+void sbitmap_queue_resize(struct sbitmap_queue *sbq, unsigned int depth);
+
+/**
+ * __sbitmap_queue_get() - Try to allocate a free bit from a &struct
+ * sbitmap_queue with preemption already disabled.
+ * @sbq: Bitmap queue to allocate from.
+ *
+ * Return: Non-negative allocated bit number if successful, -1 otherwise.
+ */
+int __sbitmap_queue_get(struct sbitmap_queue *sbq);
+
+/**
+ * __sbitmap_queue_get_batch() - Try to allocate a batch of free bits
+ * @sbq: Bitmap queue to allocate from.
+ * @nr_tags: number of tags requested
+ * @offset: offset to add to returned bits
+ *
+ * Return: Mask of allocated tags, 0 if none are found. Each tag allocated is
+ * a bit in the mask returned, and the caller must add @offset to the value to
+ * get the absolute tag value.
+ */
+unsigned long __sbitmap_queue_get_batch(struct sbitmap_queue *sbq, int nr_tags,
+ unsigned int *offset);
+
+/**
+ * sbitmap_queue_get_shallow() - Try to allocate a free bit from a &struct
+ * sbitmap_queue, limiting the depth used from each word, with preemption
+ * already disabled.
+ * @sbq: Bitmap queue to allocate from.
+ * @shallow_depth: The maximum number of bits to allocate from a single word.
+ * See sbitmap_get_shallow().
+ *
+ * If you call this, make sure to call sbitmap_queue_min_shallow_depth() after
+ * initializing @sbq.
+ *
+ * Return: Non-negative allocated bit number if successful, -1 otherwise.
+ */
+int sbitmap_queue_get_shallow(struct sbitmap_queue *sbq,
+ unsigned int shallow_depth);
+
+/**
+ * sbitmap_queue_get() - Try to allocate a free bit from a &struct
+ * sbitmap_queue.
+ * @sbq: Bitmap queue to allocate from.
+ * @cpu: Output parameter; will contain the CPU we ran on (e.g., to be passed to
+ * sbitmap_queue_clear()).
+ *
+ * Return: Non-negative allocated bit number if successful, -1 otherwise.
+ */
+static inline int sbitmap_queue_get(struct sbitmap_queue *sbq,
+ unsigned int *cpu)
+{
+ int nr;
+
+ *cpu = get_cpu();
+ nr = __sbitmap_queue_get(sbq);
+ put_cpu();
+ return nr;
+}
+
+/**
+ * sbitmap_queue_min_shallow_depth() - Inform a &struct sbitmap_queue of the
+ * minimum shallow depth that will be used.
+ * @sbq: Bitmap queue in question.
+ * @min_shallow_depth: The minimum shallow depth that will be passed to
+ * sbitmap_queue_get_shallow() or __sbitmap_queue_get_shallow().
+ *
+ * sbitmap_queue_clear() batches wakeups as an optimization. The batch size
+ * depends on the depth of the bitmap. Since the shallow allocation functions
+ * effectively operate with a different depth, the shallow depth must be taken
+ * into account when calculating the batch size. This function must be called
+ * with the minimum shallow depth that will be used. Failure to do so can result
+ * in missed wakeups.
+ */
+void sbitmap_queue_min_shallow_depth(struct sbitmap_queue *sbq,
+ unsigned int min_shallow_depth);
+
+/**
+ * sbitmap_queue_clear() - Free an allocated bit and wake up waiters on a
+ * &struct sbitmap_queue.
+ * @sbq: Bitmap to free from.
+ * @nr: Bit number to free.
+ * @cpu: CPU the bit was allocated on.
+ */
+void sbitmap_queue_clear(struct sbitmap_queue *sbq, unsigned int nr,
+ unsigned int cpu);
+
+/**
+ * sbitmap_queue_clear_batch() - Free a batch of allocated bits
+ * &struct sbitmap_queue.
+ * @sbq: Bitmap to free from.
+ * @offset: offset for each tag in array
+ * @tags: array of tags
+ * @nr_tags: number of tags in array
+ */
+void sbitmap_queue_clear_batch(struct sbitmap_queue *sbq, int offset,
+ int *tags, int nr_tags);
+
+static inline int sbq_index_inc(int index)
+{
+ return (index + 1) & (SBQ_WAIT_QUEUES - 1);
+}
+
+static inline void sbq_index_atomic_inc(atomic_t *index)
+{
+ int old = atomic_read(index);
+ int new = sbq_index_inc(old);
+ atomic_cmpxchg(index, old, new);
+}
+
+/**
+ * sbq_wait_ptr() - Get the next wait queue to use for a &struct
+ * sbitmap_queue.
+ * @sbq: Bitmap queue to wait on.
+ * @wait_index: A counter per "user" of @sbq.
+ */
+static inline struct sbq_wait_state *sbq_wait_ptr(struct sbitmap_queue *sbq,
+ atomic_t *wait_index)
+{
+ struct sbq_wait_state *ws;
+
+ ws = &sbq->ws[atomic_read(wait_index)];
+ sbq_index_atomic_inc(wait_index);
+ return ws;
+}
+
+/**
+ * sbitmap_queue_wake_all() - Wake up everything waiting on a &struct
+ * sbitmap_queue.
+ * @sbq: Bitmap queue to wake up.
+ */
+void sbitmap_queue_wake_all(struct sbitmap_queue *sbq);
+
+/**
+ * sbitmap_queue_wake_up() - Wake up some of waiters in one waitqueue
+ * on a &struct sbitmap_queue.
+ * @sbq: Bitmap queue to wake up.
+ * @nr: Number of bits cleared.
+ */
+void sbitmap_queue_wake_up(struct sbitmap_queue *sbq, int nr);
+
+/**
+ * sbitmap_queue_show() - Dump &struct sbitmap_queue information to a &struct
+ * seq_file.
+ * @sbq: Bitmap queue to show.
+ * @m: struct seq_file to write to.
+ *
+ * This is intended for debugging. The format may change at any time.
+ */
+void sbitmap_queue_show(struct sbitmap_queue *sbq, struct seq_file *m);
+
+struct sbq_wait {
+ struct sbitmap_queue *sbq; /* if set, sbq_wait is accounted */
+ struct wait_queue_entry wait;
+};
+
+#define DEFINE_SBQ_WAIT(name) \
+ struct sbq_wait name = { \
+ .sbq = NULL, \
+ .wait = { \
+ .private = current, \
+ .func = autoremove_wake_function, \
+ .entry = LIST_HEAD_INIT((name).wait.entry), \
+ } \
+ }
+
+/*
+ * Wrapper around prepare_to_wait_exclusive(), which maintains some extra
+ * internal state.
+ */
+void sbitmap_prepare_to_wait(struct sbitmap_queue *sbq,
+ struct sbq_wait_state *ws,
+ struct sbq_wait *sbq_wait, int state);
+
+/*
+ * Must be paired with sbitmap_prepare_to_wait().
+ */
+void sbitmap_finish_wait(struct sbitmap_queue *sbq, struct sbq_wait_state *ws,
+ struct sbq_wait *sbq_wait);
+
+/*
+ * Wrapper around add_wait_queue(), which maintains some extra internal state
+ */
+void sbitmap_add_wait_queue(struct sbitmap_queue *sbq,
+ struct sbq_wait_state *ws,
+ struct sbq_wait *sbq_wait);
+
+/*
+ * Must be paired with sbitmap_add_wait_queue()
+ */
+void sbitmap_del_wait_queue(struct sbq_wait *sbq_wait);
+
+#endif /* __LINUX_SCALE_BITMAP_H */
generated by cgit v1.2.3 (git 2.39.1) at 2024-06-10 07:02:02 +0000