打不开设备

Question

我有一个小问题。我将此模块安装到我的内核中，并将其写在 /proc 下

当我尝试从用户模式打开（）它时，我收到以下消息：

“无法打开设备文件：my_dev”

static int module_permission(struct inode *inode, int op, struct nameidata *foo)
{
 //if its write
 if ((op == 2)&&(writer == DOESNT_EXIST)){
  writer = EXIST ;
  return 0;
 }
 //if its read
 if (op == 4 ){
  numOfReaders++;
  return 0;
 }
 return -EACCES;
}

int procfs_open(struct inode *inode, struct file *file)
{
 try_module_get(THIS_MODULE);
 return 0;
}

static struct file_operations File_Ops_4_Our_Proc_File = {
 .read   = procfs_read,
 .write   = procfs_write,
 .open   = procfs_open,
 .release = procfs_close,
};

static struct inode_operations Inode_Ops_4_Our_Proc_File = {
 .permission = module_permission, /* check for permissions */
};

int init_module()
{
 /* create the /proc file */
 Our_Proc_File = create_proc_entry(PROC_ENTRY_FILENAME, 0644, NULL);
 /* check if the /proc file was created successfuly */
 if (Our_Proc_File == NULL){
  printk(KERN_ALERT "Error: Could not initialize /proc/%s\n",
         PROC_ENTRY_FILENAME);
  return -ENOMEM;
 }

 Our_Proc_File->owner = THIS_MODULE;
 Our_Proc_File->proc_iops = &Inode_Ops_4_Our_Proc_File;
 Our_Proc_File->proc_fops = &File_Ops_4_Our_Proc_File;
 Our_Proc_File->mode = S_IFREG | S_IRUGO | S_IWUSR;
 Our_Proc_File->uid = 0;
 Our_Proc_File->gid = 0;
 Our_Proc_File->size = 80;

 //i added init the writewr status
 writer = DOESNT_EXIST;
 numOfReaders = 0 ;
 printk(KERN_INFO "/proc/%s created\n", PROC_ENTRY_FILENAME);
 return 0;
}

Answer 1

open("/proc/ex3mod", O_WRONLY) = -1 EACCES (Permission denied)

就像之前的评论者所说，您没有打开 proc 文件的权限。尝试使用chmod 修复权限。