LXR linux/include/linux/percpu

   1#ifndef __PERCPU_IDA_H__
   2#define __PERCPU_IDA_H__
   3
   4#include <linux/types.h>
   5#include <linux/bitops.h>
   6#include <linux/init.h>
   7#include <linux/sched.h>
   8#include <linux/spinlock_types.h>
   9#include <linux/wait.h>
  10#include <linux/cpumask.h>
  11
  12struct percpu_ida_cpu;
  13
  14struct percpu_ida {
  15        /*
  16         * number of tags available to be allocated, as passed to
  17         * percpu_ida_init()
  18         */
  19        unsigned                        nr_tags;
  20        unsigned                        percpu_max_size;
  21        unsigned                        percpu_batch_size;
  22
  23        struct percpu_ida_cpu __percpu  *tag_cpu;
  24
  25        /*
  26         * Bitmap of cpus that (may) have tags on their percpu freelists:
  27         * steal_tags() uses this to decide when to steal tags, and which cpus
  28         * to try stealing from.
  29         *
  30         * It's ok for a freelist to be empty when its bit is set - steal_tags()
  31         * will just keep looking - but the bitmap _must_ be set whenever a
  32         * percpu freelist does have tags.
  33         */
  34        cpumask_t                       cpus_have_tags;
  35
  36        struct {
  37                spinlock_t              lock;
  38                /*
  39                 * When we go to steal tags from another cpu (see steal_tags()),
  40                 * we want to pick a cpu at random. Cycling through them every
  41                 * time we steal is a bit easier and more or less equivalent:
  42                 */
  43                unsigned                cpu_last_stolen;
  44
  45                /* For sleeping on allocation failure */
  46                wait_queue_head_t       wait;
  47
  48                /*
  49                 * Global freelist - it's a stack where nr_free points to the
  50                 * top
  51                 */
  52                unsigned                nr_free;
  53                unsigned                *freelist;
  54        } ____cacheline_aligned_in_smp;
  55};
  56
  57/*
  58 * Number of tags we move between the percpu freelist and the global freelist at
  59 * a time
  60 */
  61#define IDA_DEFAULT_PCPU_BATCH_MOVE     32U
  62/* Max size of percpu freelist, */
  63#define IDA_DEFAULT_PCPU_SIZE   ((IDA_DEFAULT_PCPU_BATCH_MOVE * 3) / 2)
  64
  65int percpu_ida_alloc(struct percpu_ida *pool, int state);
  66void percpu_ida_free(struct percpu_ida *pool, unsigned tag);
  67
  68void percpu_ida_destroy(struct percpu_ida *pool);
  69int __percpu_ida_init(struct percpu_ida *pool, unsigned long nr_tags,
  70        unsigned long max_size, unsigned long batch_size);
  71static inline int percpu_ida_init(struct percpu_ida *pool, unsigned long nr_tags)
  72{
  73        return __percpu_ida_init(pool, nr_tags, IDA_DEFAULT_PCPU_SIZE,
  74                IDA_DEFAULT_PCPU_BATCH_MOVE);
  75}
  76
  77typedef int (*percpu_ida_cb)(unsigned, void *);
  78int percpu_ida_for_each_free(struct percpu_ida *pool, percpu_ida_cb fn,
  79        void *data);
  80
  81unsigned percpu_ida_free_tags(struct percpu_ida *pool, int cpu);
  82#endif /* __PERCPU_IDA_H__ */
  83