内核线程执行 [英] Kernel Thread implementation

问题描述

我写了下面code创建内核线程：

I wrote the following code to create a kernel thread:

#include<linux/init.h>
#include<linux/module.h>
#include<linux/kernel.h>
#include<linux/kthread.h>
#include<linux/sched.h>

struct task_struct *task;
int data;
int ret;
int thread_function(void *data)
{
    int var;
    var = 10;
    return var;
}

static int kernel_init(void)
{
    data = 20;
    printk(KERN_INFO"--------------------------------------------");
    task = kthread_create(&thread_function,(void *)data,"pradeep");
    task = kthread_run(&thread_function,(void *)data,"pradeep");
    printk(KERN_INFO"Kernel Thread : %s\n",task->comm);
    return 0;
}

static void kernel_exit(void)
{
    ret = kthread_stop(task);
}

module_init(kernel_init);
module_exit(kernel_exit);

在给insmod命令，我可以创建一个名为普拉迪普内核线程，我可以用看到新的线程
PS -ef 命令如下：

On giving the insmod command, I am able to create a kernel thread named "pradeep" and I can see the new thread using the ps -ef command as follows

root      6071     2  0 10:21 ?        00:00:00 [pradeep]

和其父是kthreadd的PID为2。
但我无法停止对给 rmmod的命令这个线程。这是给下面的输出：

and its parent is kthreadd whose PID is 2. But I am not able to stop this thread on giving rmmod command. It is giving the following output:

ERROR: Removing 'pradeep': Device or resource busy.

有人可以告诉我怎么杀这个主题？

Can somebody please tell me how to kill this thread?

推荐答案

您应该只使用 kthread_create之一（）或 kthread_run（）：

/**
 * kthread_run - create and wake a thread.
 * @threadfn: the function to run until signal_pending(current).
 * @data: data ptr for @threadfn.
 * @namefmt: printf-style name for the thread.
 *
 * Description: Convenient wrapper for kthread_create() followed by
 * wake_up_process().  Returns the kthread or ERR_PTR(-ENOMEM).
 */
#define kthread_run(threadfn, data, namefmt, ...)                      \
({                                                                     \
    struct task_struct *__k                                            \
            = kthread_create(threadfn, data, namefmt, ## __VA_ARGS__); \
    if (!IS_ERR(__k))                                                  \
            wake_up_process(__k);                                      \
    __k;                                                               \
})

所以，你要创建的两个的线程和漏水的其中之一：

So you're creating two threads and leaking one of them:

task = kthread_create(&thread_function,(void*) &data,"pradeep");
task = kthread_run(&thread_function,(void*) &data,"pradeep");

此外，你的线程功能可能会丢失一些细节：

Furthermore, your thread function might be missing some details:

/**
 * kthread_create - create a kthread.
 * @threadfn: the function to run until signal_pending(current).
 * @data: data ptr for @threadfn.
 * @namefmt: printf-style name for the thread.
 *
 * Description: This helper function creates and names a kernel
 * thread.  The thread will be stopped: use wake_up_process() to start
 * it.  See also kthread_run().
 *
 * When woken, the thread will run @threadfn() with @data as its
 * argument. @threadfn() can either call do_exit() directly if it is a
 * standalone thread for which noone will call kthread_stop(), or
 * return when 'kthread_should_stop()' is true (which means
 * kthread_stop() has been called).  The return value should be zero
 * or a negative error number; it will be passed to kthread_stop().
 *
 * Returns a task_struct or ERR_PTR(-ENOMEM).
 */

我觉得两种选择终止线程是：

I think the two choices for terminating a thread are:

1. 呼叫 do_exit（）时，即可大功告成。


2. 返回一个值时，另一个线程调用 kthread_stop（）。

1. Call do_exit() when you're done.
2. Return a value when another thread calls kthread_stop().

希望解决这些两个小问题后，你就会有一个功能线程的创建者/收割机。

Hopefully after fixing these two small problems, you'll have a functional thread creator / reaper.

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