class_create 和 device_create 引起的内核崩溃

最新推荐文章于 2023-08-09 16:54:21 发布

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本文介绍了一个导致内核崩溃的LED设备驱动代码示例，并提供了修改建议以避免崩溃并自动生成设备文件。

如下代码可运行，总是会导致内核崩溃：

基于2.6内核 CentOS5.5

#include <linux/module.h>
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/types.h>
#include <linux/fs.h>
#include <linux/cdev.h>
#include <linux/device.h>


uint led_major =0 ,led_minor = 0;
dev_t led_dev_no;

module_param(led_major,uint,S_IWUGO);

struct cdev led_cdev;

static struct class  *dev_class = NULL;
static struct device *dev_device = NULL;



static int leddev_open(struct inode *inode, struct file *file)
{
    printk("ledev_open\n");
    return 0;
}
static ssize_t leddev_read(struct file *file,char __user *userbuf,size_t count, loff_t *ppos)
{   
    printk("leddev_read\n");
    return 0;
}

static ssize_t leddev_write(struct file *file, const char __user *buffer,size_t size, loff_t *ppos)
{
    printk("leddev_write\n");
    return 0;

}
static int leddev_close(struct inode *inode, struct file *file)
{
    printk("leddev_close\n");
    return 0;
}


struct file_operations leddev_fops = 
{
    .owner = THIS_MODULE,
    .open  = leddev_open,
    .read  = leddev_read,
    .write = leddev_write,
    .release = leddev_close
};


static int __init leddev_init(void)
{
    int result;
    led_dev_no= MKDEV(led_major,led_minor);
    if(led_major)
    {
        result = register_chrdev_region(led_dev_no,1,"leddev");
    }
    else
    {
        result = alloc_chrdev_region(&led_dev_no,0,1,"leddev");
    }

    if(result < 0)

    {
        printk(KERN_WARNING"led: can't get major %d\n",led_major);
        return result;
    }

    
    cdev_init(&led_cdev, &leddev_fops);
    led_cdev.owner = THIS_MODULE;
    result = cdev_add(&led_cdev,led_dev_no,1);
    if(result < 0)
    {
        printk(KERN_WARNING"led: can'cdev_add ");
        goto fail_alloc_chrdev_region;
    }
    
    dev_class = class_create(THIS_MODULE,"leddev");
    if(IS_ERR(dev_class))
    {
        printk("class_create failed\n");
        result = PTR_ERR(dev_class);
        goto  fail_class_create;
    }
    dev_device = device_create(dev_class,NULL,led_dev_no,NULL,"leddev");
    if(IS_ERR(dev_device))
    {
        printk("class_create failed\n");
        result = PTR_ERR(dev_device);
        goto  fail_device_create;
    }

    
    
	return 0;
fail_device_create:
    class_destroy(dev_class);   

fail_class_create:
    cdev_del(&led_cdev);
    
fail_alloc_chrdev_region:
    unregister_chrdev_region(led_dev_no,1);
    return result;
    
}
static void __exit leddev_exit(void)
{ 
    device_destroy(dev_class,led_dev_no);
    class_destroy(dev_class);
    unregister_chrdev_region(led_dev_no,1);
    cdev_del(&led_cdev);
    return ;
}



module_init(leddev_init);
module_exit(leddev_exit);

MODULE_LICENSE("GPL");

dev_device = device_create(dev_class,NULL,led_dev_no,NULL,"leddev"); 改为

<pre name="code" class="cpp">dev_device = class_device_create(dev_class,NULL,led_dev_no,NULL,"leddev"); 内核不再崩溃

自动生成设备文件

[root@Tech automkod]# ll /dev/leddev 
crw------- 1 root root 252, 0 07-11 01:09 /dev/leddev