how to include linux kernel header files - linux-kernel

Question

I am attempting some Linux kernel development.
I have a problem in including a header file sched.h (which exists in the path /usr/src/linux-3.12.26/kernel/sched, not in /usr/src/linux-3.12.26/include/linux ).
But when I "sudo make -C /usr/src/linux-3.12.26/ M=$(pwd) modules" I got the error "fatal error: kernel/sched/sched.h: doesn't exist"
Here is my code:
#include <linux/init.h>
#include <linux/module.h>
#include <linux/percpu.h>
#include </usr/src/linux-3.12.26/kernel/sched/sched.h>
int __init init_current(void){
int cpu_num=0;
struct task_struct *p;
for(cpu_num=0;cpu_num<8;cpu_num++)
{
p=curr_task(cpu_num);
printk(KERN_ALERT "current task on cpu %d is %d\n", cpu_num, p->pid);
}
return 0;
}
void __exit exit_current(void)
{
printk(KERN_ALERT "FINISHED！\n");
}
MODULE_LICENSE("GPL");
module_init(init_current);
module_exit(exit_current);
There may be some errors in the code. My intention is to get the current running process in different cores.
#Santosh A .Thanks for continuing concerning my puzzle.After I changed the Makefile in /usr/src/linux-3.12.26/(see my answer above，it may not be normative,but work ),the headers I include can be found.Then I get another problem. Here is my code:
#include <linux/init.h>
#include <linux/module.h>
//#include <linux/sched.h>
#include <linux/percpu.h>
#include <sched/sched.h>
static int __init init_current(void){
int cpu_num=0;
extern struct task_struct *p;
struct rq *q;
extern struct rq * cpu_rq(int);
for(cpu_num=0;cpu_num<8;cpu_num++)
{
q=cpu_rq(cpu_num);
p=q->curr;
printk(KERN_ALERT "current task on cpu %d is %d\n", cpu_num, p->pid);
}
return 0;
}
static void __exit exit_current(void)
{
printk(KERN_ALERT "FINISHED！\n");
}
MODULE_LICENSE("GPL");
module_init(init_current);
module_exit(exit_current);
Here is error info:
/home/wison/code/current/current.c: In function ‘init_current’:
kernel/sched/sched.h:539:23: error: expected identifier or ‘(’ before ‘&’ token
#define cpu_rq(cpu) (&per_cpu(runqueues, (cpu)))
^
/home/wison/code/current/current.c:11:28: note: in expansion of macro ‘cpu_rq’
extern struct rq * cpu_rq(int);