LXR linux/include/linux/percpu.h

   1#ifndef __LINUX_PERCPU_H
   2#define __LINUX_PERCPU_H
   3#include <linux/spinlock.h> /* For preempt_disable() */
   4#include <linux/slab.h> /* For kmalloc() */
   5#include <linux/smp.h>
   6#include <linux/string.h> /* For memset() */
   7#include <asm/percpu.h>
   8
   9/* Enough to cover all DEFINE_PER_CPUs in kernel, including modules. */
  10#ifndef PERCPU_ENOUGH_ROOM
  11#define PERCPU_ENOUGH_ROOM 32768
  12#endif
  13
  14/* Must be an lvalue. */
  15#define get_cpu_var(var) (*({ preempt_disable(); &__get_cpu_var(var); }))
  16#define put_cpu_var(var) preempt_enable()
  17
  18#ifdef CONFIG_SMP
  19
  20struct percpu_data {
  21        void *ptrs[NR_CPUS];
  22};
  23
  24/* 
  25 * Use this to get to a cpu's version of the per-cpu object allocated using
  26 * alloc_percpu.  Non-atomic access to the current CPU's version should
  27 * probably be combined with get_cpu()/put_cpu().
  28 */ 
  29#define per_cpu_ptr(ptr, cpu)                   \
  30({                                              \
  31        struct percpu_data *__p = (struct percpu_data *)~(unsigned long)(ptr); \
  32        (__typeof__(ptr))__p->ptrs[(cpu)];      \
  33})
  34
  35extern void *__alloc_percpu(size_t size);
  36extern void free_percpu(const void *);
  37
  38#else /* CONFIG_SMP */
  39
  40#define per_cpu_ptr(ptr, cpu) ({ (void)(cpu); (ptr); })
  41
  42static inline void *__alloc_percpu(size_t size)
  43{
  44        void *ret = kmalloc(size, GFP_KERNEL);
  45        if (ret)
  46                memset(ret, 0, size);
  47        return ret;
  48}
  49static inline void free_percpu(const void *ptr)
  50{       
  51        kfree(ptr);
  52}
  53
  54#endif /* CONFIG_SMP */
  55
  56/* Simple wrapper for the common case: zeros memory. */
  57#define alloc_percpu(type)      ((type *)(__alloc_percpu(sizeof(type))))
  58
  59#endif /* __LINUX_PERCPU_H */
  60