OSCL-LXR linux-6.0.1/​include/​linux/​sbitmap.h	Source navigation Diff markup Identifier search General search
	Version: linux-6.0.1 spark-3.0.0 hadoop-3.2.0-src hadoop-3.3.0-src spark-2.4.7 linux-4.15.13 hadoop-2.7.4-src Revert   Change

 /* 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_cnt: Number of frees remaining before we wake up.
      */
     atomic_t wait_cnt;
 
     /**
      * @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;
 };
 
 /**
  * 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.
  */
 void sbitmap_queue_wake_up(struct sbitmap_queue *sbq);
 
 /**
  * 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 */

This page was automatically generated by the 2.1.0 LXR engine. The LXR team