LDD3中scull的例子

scull模块我已经编译成功，另外我在网上找了个测试程序想测试一下，但编译的时候老是出问题：

In file included from ioctl_test.c:5:
scull.h:34: error: field ‘sem’ has incomplete type
scull.h:35: error: field ‘cdev’ has incomplete type

源代码：
C/C++ code

#include <sys/ioctl.h>   
#include <fcntl.h>  
#include <stdlib.h>  
#include <stdio.h>  
#include "scull.h"  
    
  
int main()  
{  
    int code = 0;  
  
    ……
  
    exit(0);  
}  

我网上查了一下，说好像是用户空间和内核空间的问题，但还是没弄明白，希望有人能指点一下。

补一下涉及的结构体：
C/C++ code

struct scull_dev {
    struct scull_qset *data;  /* Pointer to first quantum set */
    int quantum;              /* the current quantum size */
    int qset;                 /* the current array size */
    unsigned long size;       /* amount of data stored here */
    unsigned int access_key;  /* used by sculluid and scullpriv */
    struct semaphore sem;     /* mutual exclusion semaphore     */
    struct cdev cdev;      /* Char device structure        */
};