[英]Problem of _do_fork() in Linux kernel module programming
I am new to Linux programming, and I am stuck in trouble when programming a loadable kernel module for the Operating System course. 我是Linux编程的新手,为操作系统课程编程可加载的内核模块时遇到麻烦。 In this task, I need to create a kernel thread when initializing the module, and then run a function. 在此任务中,我需要在初始化模块时创建一个内核线程,然后运行一个函数。 Within the function, a child process should be created by using _do_fork() routine defined in kernel/fork.c. 在该函数内,应使用kernel / fork.c中定义的_do_fork()例程创建一个子进程。 The parameter list of _do_fork is as below: _do_fork的参数列表如下:
long _do_fork(unsigned long clone_flags,
unsigned long stack_start,
unsigned long stack_size,
int __user *parent_tidptr,
int __user *child_tidptr,
unsigned long tls)
My question is how to fill out the parameter "stack_start"? 我的问题是如何填写参数“ sttack_start”? I know it specifies the location of stack which is used by the child process. 我知道它指定了子进程使用的堆栈的位置。 Any one can give me an example of how to use _do_fork()? 谁能给我一个有关如何使用_do_fork()的示例?
Here attaches part of my code: 这里附上我的部分代码:
static struct task_struct *task;
int my_fork(void *argc){
long pid = 0;
/* fork a process using do_fork */
pid = _do_fork(SIGCHLD, ???, 0, NULL, NULL, 0);
printk("This is child process with pid %ld\n", pid);
return 0;
}
static int __init program2_init(void){
printk("[program2] : Module_init\n");
/* create a kernel thread to run my_fork */
task = kthread_create(&my_fork, NULL, "GoodThread");
// wake up the thread
if (!IS_ERR(task)) {
printk("kthread starts\n");
wake_up_process(task);
}
return 0;
}
And requirement in this assignment is attached: 并附上此作业的要求:
When program2.ko being initialized, create a kernel thread and run my_fork function. 初始化program2.ko时,创建一个内核线程并运行my_fork函数。 (10 points) Within my_fork, fork a process to execute the test program. (10分)在my_fork中,派生一个进程来执行测试程序。 (10 points) (10点)
Hints: 1) Use “_do_fork” to fork a new process. 提示:1)使用“ _do_fork”派生一个新进程。 (/kernel/fork.c) (/kernel/fork.c)
Thanks a lot!!! 非常感谢!!!
If you search for uses of _do_fork
, you will find, for instance, kernel_thread
in kernel/fork.c
: 如果搜索_do_fork
用途, _do_fork
,您将在kernel/fork.c
找到kernel_thread
:
/*
* Create a kernel thread.
*/
pid_t kernel_thread(int (*fn)(void *), void *arg, unsigned long flags)
{
return _do_fork(flags|CLONE_VM|CLONE_UNTRACED, (unsigned long)fn,
(unsigned long)arg, NULL, NULL, 0);
}
which is a very good example of how to create a kernel thread using _do_fork
! 这是如何使用_do_fork
创建内核线程的一个很好的例子! ;) ;)
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