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