我正在开发与用户空间程序通信的Linux内核模块。该模块等待从用户空间发送的消息，以便在内核模式下进行打印。
这是模块：
#include <linux/init.h>
#include <linux/module.h>
#include <linux/fs.h>
#include <linux/device.h>
#include <linux/kernel.h>
#include <linux/uaccess.h>
MODULE_LICENSE("GPL");
MODULE_AUTHOR("Gaston");
MODULE_DESCRIPTION("A simple Linux char driver");
MODULE_VERSION("0.1");
#define MAX 256
static char message[MAX] =""; ///< Memory for the string that is passed from userspace
ssize_t exer_open(struct inode *pinode, struct file *pfile) {
printk(KERN_INFO "Device has been opened\n");
return 0;
}
ssize_t exer_read(struct file *pfile, char __user *buffer, size_t length, loff_t *offset) {
return 0;
}
ssize_t exer_write(struct file *pfile, const char __user *buffer, size_t length, loff_t *offset) {
if (length > MAX)
return -EINVAL;
if (copy_from_user(message, buffer, length) != 0)
return -EFAULT;
printk(KERN_INFO "Received %s characters from the user\n", message);
return 0;
}
ssize_t exer_close(struct inode *pinode, struct file *pfile) {
printk(KERN_INFO "Device successfully closed\n");
return 0;
}
struct file_operations exer_file_operations = {
.owner = THIS_MODULE,
.open = exer_open,
.read = exer_read,
.write = exer_write,
.release = exer_close,
};
int exer_simple_module_init(void) {
printk(KERN_INFO "Initializing the LKM\n");
register_chrdev(240, "Simple Char Drv", &exer_file_operations);
return 0;
}
void exer_simple_module_exit(void) {
unregister_chrdev(240, "Simple Char Drv");
}
module_init(exer_simple_module_init);
module_exit(exer_simple_module_exit);
这是用户空间程序：
#include<stdio.h>
#include<stdlib.h>
#include<errno.h>
#include<fcntl.h>
#include<string.h>
#include<unistd.h>
#define BUFFER_LENGTH 256
int main()
{
int ret, fd;
char stringToSend[BUFFER_LENGTH];
fd = open("/dev/char_device", O_RDWR); // Open the device with read/write access
if (fd < 0)
{
perror("Failed to open the device...");
return errno;
}
printf("Type in a short string to send to the kernel module:\n");
scanf("%s", stringToSend); // Read in a string (with spaces)
printf("Writing message to the device [%s].\n", stringToSend);
ret = write(fd, stringToSend, strlen(stringToSend)); // Send the string to the LKM
if (ret < 0)
{
perror("Failed to write the message to the device.");
return errno;
}
return 0;
}
这工作正常，并且我从用户空间输入的消息被打印在内核空间中。
现在，我使用此示例来学习内核线程编程。
我试图使LKM写函数成为内核线程必须执行的函数，所以我像这样修改了模块：
#include <linux/init.h>
#include <linux/module.h>
#include <linux/fs.h>
#include <linux/device.h>
#include <linux/kernel.h>
#include <linux/uaccess.h>
#include <linux/kthread.h>
MODULE_LICENSE("GPL");
MODULE_AUTHOR("Gaston");
MODULE_DESCRIPTION("A simple Linux char driver");
MODULE_VERSION("0.1");
#define MAX 256
static struct task_struct *thread1;
static char message[MAX] =""; ///< Memory for the string that is passed from userspace
ssize_t exer_open(struct inode *pinode, struct file *pfile) {
printk(KERN_INFO "Device has been opened\n");
return 0;
}
ssize_t exer_write(struct file *pfile, const char __user *buffer, size_t length, loff_t *offset) {
if (length > MAX)
return -EINVAL;
printk("Thread_fuction is running ...\n");
if (copy_from_user(message, buffer, length) != 0)
return -EFAULT;
printk(KERN_INFO "Received this message : %s ,from the user\n", message);
return 0;
}
struct file_operations exer_file_operations = {
.owner = THIS_MODULE,
.open = exer_open,
.write = exer_write,
};
int exer_simple_module_init(void) {
char our_thread[8]="thread1";
printk(KERN_INFO "Initializing the LKM\n");
register_chrdev(240, "Simple Char Drv", &exer_file_operations);
thread1 = kthread_create(exer_write,NULL,our_thread);
if((thread1))
{
printk(KERN_INFO "Thread is created");
wake_up_process(thread1);
}
return 0;
}
void exer_simple_module_exit(void) {
int ret;
unregister_chrdev(240, "Simple Char Drv");
ret = kthread_stop(thread1);
if(!ret)
printk(KERN_INFO "Thread stopped");
}
module_init(exer_simple_module_init);
module_exit(exer_simple_module_exit);
这里的问题，当我编译模块时，发生错误：
/exer_simple_char_drv.c:63:27：错误：传递的参数1为
指针类型不兼容的“ kthread_create_on_node”
[-Werror =不兼容的指针类型] thread1 =
kthread_create（exer_write，NULL，our_thread）;
搜索网络，发现通过调用该函数创建了一个线程：
struct task_struct *kthread_create(int (*function)(void *data), void *data, const char name[], ...)
该函数具有第一个参数，即线程必须执行的函数，并且具有参数
(void *data)，但是，我的写内核函数没有相同的参数：ssize_t exer_write(struct file *pfile, const char __user *buffer, size_t length, loff_t *offset)
请问有办法解决这个问题吗？如何修改我的Linux内核以将
write函数作为线程执行？谢谢。
最佳答案
你不能您的线程函数必须使用以下格式：
int my_thread_function(void *data)
您可以随心所欲地调用它-不必将其称为
my_thread_function-且不必将参数称为data，但它必须是void *。这将不起作用：
ssize_t exer_write(struct file *pfile, const char __user *buffer, size_t length, loff_t *offset)
我建议编写一个新函数作为您的线程函数：
int exer_write_in_thread(void *data) {
exer_write(???, ???, ???, ???);
return 0;
}
显然，您必须弄清楚要使用什么参数调用
exer_write。