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/sched.h>
   8 #include <linux/spinlock_types.h>
   9 #include <linux/wait.h>
  10 #include <linux/cpumask.h>
  11
  12 struct percpu_ida_cpu;
  13
  14 struct 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
  65 int percpu_ida_alloc(struct percpu_ida *pool, int state);
  66 void percpu_ida_free(struct percpu_ida *pool, unsigned tag);
  67
  68 void percpu_ida_destroy(struct percpu_ida *pool);
  69 int __percpu_ida_init(struct percpu_ida *pool, unsigned long nr_tags,
  70         unsigned long max_size, unsigned long batch_size);
  71 static 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
  77 typedef int (*percpu_ida_cb)(unsigned, void *);
  78 int percpu_ida_for_each_free(struct percpu_ida *pool, percpu_ida_cb fn,
  79         void *data);
  80
  81 unsigned percpu_ida_free_tags(struct percpu_ida *pool, int cpu);
  82 #endif /* __PERCPU_IDA_H__ */