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