编写模块遍历系统中的进程
源程序：list.c
/*****************************************
*功能:利用进程链表遍历当前系统中的所有进程
*同时可以打印出进程的相关信息
*
* ***************************************/
#include <linux/list.h>
#include <linux/module.h>
#include <linux/init.h>
#include <linux/sched.h>
#define METHOD 2
static int list_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 = NULL;
task = NULL;
pos = NULL;
method = NULL;
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("系统当前共 %d 个进程!!", count);
return 0;
}
static void list_exit(void)
{
printk( KERN_ALERT "GOOD BYE!!\n");
}
module_init( list_init );
module_exit( list_exit );
MODULE_AUTHOR( "Along" );
MODULE_LICENSE( "GPL" );
我的Makefile:
obj-m := list.o
KERNELDIR ?= /lib/modules/$(shell uname -r)/build
PWD := $(shell pwd)
all:
make -C $(KERNELDIR) M=$(PWD) modules
clean:
make -C $(KERNELDIR) M=$(PWD) clean
这个程序主要用到了几个关键的宏list_for_each,list_for_each_entry,for_each_process 。我们可以通过修改程序中 METHOD 的值查看不同宏运行产生的结果。
