include/linux/pcounter.h

   1 #ifndef __LINUX_PCOUNTER_H
   2 #define __LINUX_PCOUNTER_H
   3
   4 struct pcounter {
   5 #ifdef CONFIG_SMP
   6         void            (*add)(struct pcounter *self, int inc);
   7         int             (*getval)(const struct pcounter *self);
   8         int             *per_cpu_values;
   9 #else
  10         int             val;
  11 #endif
  12 };
  13
  14 /*
  15  * Special macros to let pcounters use a fast version of {getvalue|add}
  16  * using a static percpu variable per pcounter instead of an allocated one,
  17  * saving one dereference.
  18  * This might be changed if/when dynamic percpu vars become fast.
  19  */
  20 #ifdef CONFIG_SMP
  21 #include <linux/cpumask.h>
  22 #include <linux/percpu.h>
  23
  24 #define DEFINE_PCOUNTER(NAME)                                   \
  25 static DEFINE_PER_CPU(int, NAME##_pcounter_values);             \
  26 static void NAME##_pcounter_add(struct pcounter *self, int inc) \
  27 {                                                               \
  28        __get_cpu_var(NAME##_pcounter_values) += inc;            \
  29 }                                                               \
  30                                                                 \
  31 static int NAME##_pcounter_getval(const struct pcounter *self)  \
  32 {                                                               \
  33        int res = 0, cpu;                                        \
  34                                                                 \
  35        for_each_possible_cpu(cpu)                               \
  36                res += per_cpu(NAME##_pcounter_values, cpu);     \
  37        return res;                                              \
  38 }
  39
  40 #define PCOUNTER_MEMBER_INITIALIZER(NAME, MEMBER)               \
  41         MEMBER = {                                              \
  42                 .add    = NAME##_pcounter_add,                  \
  43                 .getval = NAME##_pcounter_getval,               \
  44         }
  45
  46 extern void pcounter_def_add(struct pcounter *self, int inc);
  47 extern int pcounter_def_getval(const struct pcounter *self);
  48
  49 static inline int pcounter_alloc(struct pcounter *self)
  50 {
  51         int rc = 0;
  52         if (self->add == NULL) {
  53                 self->per_cpu_values = alloc_percpu(int);
  54                 if (self->per_cpu_values != NULL) {
  55                         self->add    = pcounter_def_add;
  56                         self->getval = pcounter_def_getval;
  57                 } else
  58                         rc = 1;
  59         }
  60         return rc;
  61 }
  62
  63 static inline void pcounter_free(struct pcounter *self)
  64 {
  65         if (self->per_cpu_values != NULL) {
  66                 free_percpu(self->per_cpu_values);
  67                 self->per_cpu_values = NULL;
  68                 self->getval = NULL;
  69                 self->add = NULL;
  70         }
  71 }
  72
  73 static inline void pcounter_add(struct pcounter *self, int inc)
  74 {
  75         self->add(self, inc);
  76 }
  77
  78 static inline int pcounter_getval(const struct pcounter *self)
  79 {
  80         return self->getval(self);
  81 }
  82
  83 #else /* CONFIG_SMP */
  84
  85 static inline void pcounter_add(struct pcounter *self, int inc)
  86 {
  87         self->val += inc;
  88 }
  89
  90 static inline int pcounter_getval(const struct pcounter *self)
  91 {
  92         return self->val;
  93 }
  94
  95 #define DEFINE_PCOUNTER(NAME)
  96 #define PCOUNTER_MEMBER_INITIALIZER(NAME, MEMBER)
  97 #define pcounter_alloc(self) 0
  98 #define pcounter_free(self)
  99
 100 #endif /* CONFIG_SMP */
 101
 102 #endif /* __LINUX_PCOUNTER_H */