/*************************************************************************
    > File Name: process.c
    > Author: GatieMe
    > Mail: gatieme@163.com
    > Created Time: 2016年04月01日 星期五 21时09分29秒
 ************************************************************************/



#include <linux/init.h>

#include <linux/module.h>
#include <linux/moduleparam.h>

#include <linux/sched.h>



//#define METHOD 2
static unsigned int METHOD = 1;
moudle_param(METHOD, uint,0400);

static int list_process_init(void)
{
    struct task_struct *task, *p;
    struct list_head *pos;
    int count;
    char *method;
    count = 0; /*下面这些初始化完全是为了消除编译时的警告信息*/
    p = 0;
    task = 0;
    pos = 0;
    method = 0;
    task = &init_task;

    printk(KERN_ALERT"PID\tCOMM\n");

    switch(METHOD)
    {

        case 1:

            method = "list_for_each";

            break;

        case 2:

            method = "for_each_process";

            break;

        case 3:

            method = "list_for_each_entry";

            break;

    }

    printk( "The method is %s\n", method );

#if METHOD == 1

    list_for_each( pos, &task->tasks )
    {
        p = list_entry( pos, struct task_struct, tasks );
        count++;
        printk( KERN_ALERT "%d\t%s\n", p->pid, p->comm );

    }

#elif METHOD == 2

    for_each_process(task)
    {
        count++;
        printk( KERN_ALERT "%d\t%s\n", task->pid, task->comm );
    }

#elif METHOD == 3

    list_for_each_entry( p, &task->tasks, tasks )
    {
        count++;
        printk( KERN_ALERT "%d\t%s\n", p->pid, p->comm );
    }

#endif

    printk("there are %d process in your system now...", count);

    return 0;
}

static void list_process_exit(void)
{
    printk( KERN_ALERT "GOOD BYE!!\n");
}



module_init(list_process_init);
module_exit(list_process_exit);

MODULE_AUTHOR("gatieme");
MODULE_LICENSE("GPL");