include/linux/percpu_ida.h

   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/spinlock_types.h>
   8 #include <linux/wait.h>
   9 #include <linux/cpumask.h>
  10
  11 struct percpu_ida_cpu;
  12
  13 struct percpu_ida {
  14         /*
  15          * number of tags available to be allocated, as passed to
  16          * percpu_ida_init()
  17          */
  18         unsigned                        nr_tags;
  19
  20         struct percpu_ida_cpu __percpu  *tag_cpu;
  21
  22         /*
  23          * Bitmap of cpus that (may) have tags on their percpu freelists:
  24          * steal_tags() uses this to decide when to steal tags, and which cpus
  25          * to try stealing from.
  26          *
  27          * It's ok for a freelist to be empty when its bit is set - steal_tags()
  28          * will just keep looking - but the bitmap _must_ be set whenever a
  29          * percpu freelist does have tags.
  30          */
  31         cpumask_t                       cpus_have_tags;
  32
  33         struct {
  34                 spinlock_t              lock;
  35                 /*
  36                  * When we go to steal tags from another cpu (see steal_tags()),
  37                  * we want to pick a cpu at random. Cycling through them every
  38                  * time we steal is a bit easier and more or less equivalent:
  39                  */
  40                 unsigned                cpu_last_stolen;
  41
  42                 /* For sleeping on allocation failure */
  43                 wait_queue_head_t       wait;
  44
  45                 /*
  46                  * Global freelist - it's a stack where nr_free points to the
  47                  * top
  48                  */
  49                 unsigned                nr_free;
  50                 unsigned                *freelist;
  51         } ____cacheline_aligned_in_smp;
  52 };
  53
  54 int percpu_ida_alloc(struct percpu_ida *pool, gfp_t gfp);
  55 void percpu_ida_free(struct percpu_ida *pool, unsigned tag);
  56
  57 void percpu_ida_destroy(struct percpu_ida *pool);
  58 int percpu_ida_init(struct percpu_ida *pool, unsigned long nr_tags);
  59
  60 #endif /* __PERCPU_IDA_H__ */