디바이스 드라이버 모듈 프로그래밍

" 리눅스 매니아를 위한 커널 프로그래밍 " 이란 책으로 리눅스 프로그래밍 공부를 하고 있는데 ....
잘 되지 않는 부분이 있어서 ... 질문 올립니다 ...

 1 #include <linux/module.h>
 2 #include <linux/kernel.h>
 3 #include <linux/malloc.h>
 4 #include <linux/fs.h>
 5 #include <asm/uaccess.h>
 6
 7 #define DEVICE_NAME "mydrv"
 8 #define MYDRV_MAJOR 250
 9
10 static int mydrv_open(struct inode *inode, struct file *file)
11 {
12     if (MAJOR(inode->i_rdev)!=MYDRV_MAJOR)
13         return -1;
14     MOD_INC_USE_COUNT;
15     return 0;
16 }
17
18 static int mydrv_release(struct inode * inode, struct file *file)
19 {
20     if (MAJOR(inode->i_rdev) != MYDRV_MAJOR)
21         return -1;
22     MOD_DEC_USE_COUNT;
23     return 0;
24 }
25
26 static ssize_t mydrv_read(struct file *file, char *buf, size_t count, loff_t *ppos)
27 {
28     printk("mydrv_read is invorked\n");
29     return 0;
30 }
31
32 static ssize_t mydrv_write(struct file *file, char *buf, size_t count, loff_t *ppos)
33 {
34     printk("mydrv_write is invoked\n");
35     return 0;
36 }
37
38 struct file_operations mydrv_fops = {
39     NULL,
40     mydrv_read,
41     mydrv_write,
42     NULL,
43     NULL,
44     NULL,
45     NULL,
46     mydrv_open,
47     NULL,
48     mydrv_release,
49     NULL,
50     NULL,
51     NULL,
52     NULL
53 };
54
55 int init_module()
56 {
57     int result;
58
59     result = register_chrdev(MYDRV_MAJOR, "mydrv", &mydrv_fops);
60     if (result < 0) {
61         printk("mydrv : %d character device driver can't be registered\n", MYDRV_MAJOR);
62         return  result;
63     }
64
65     return 0;
66 }
67
68 void cleanup(void)
69 {
70     unregister_chrdev(MYDRV_MAJOR, "mydev");
71 }

이 프로그램을 컴파일했는데

[2002 Thu May 22 root@pulip] gcc -D__KERNEL__ -D_LINUX -DMODULE -c mydrv.c
mydrv.c:40: warning: initialization from incompatible pointer type
mydrv.c:46: warning: initialization from incompatible pointer type
mydrv.c:48: warning: initialization from incompatible pointer type

이런 에러가 뜨네여

file_operations 이란 구조체가 이상한듯 해서 .....
include/linux/fs.h 라는 파일을 뒤져보았습니다.

struct file_operations {
    struct module *owner;
    loff_t (*llseek) (struct file *, loff_t, int);
    ssize_t (*read) (struct file *, char *, size_t, loff_t *);
    ssize_t (*write) (struct file *, const char *, size_t, loff_t *);
    int (*readdir) (struct file *, void *, filldir_t);
    unsigned int (*poll) (struct file *, struct poll_table_struct *);
    int (*ioctl) (struct inode *, struct file *, unsigned int, unsigned long);
    int (*mmap) (struct file *, struct vm_area_struct *);
    int (*open) (struct inode *, struct file *);
    int (*flush) (struct file *);
    int (*release) (struct inode *, struct file *);
    int (*fsync) (struct file *, struct dentry *, int datasync);
    int (*fasync) (int, struct file *, int);
    int (*lock) (struct file *, int, struct file_lock *);
    ssize_t (*readv) (struct file *, const struct iovec *, unsigned long, loff_t *);
    ssize_t (*writev) (struct file *, const struct iovec *, unsigned long, loff_t *);
    ssize_t (*sendpage) (struct file *, struct page *, int, size_t, loff_t *, int);
    unsigned long (*get_unmapped_area)(struct file *, unsigned long, unsigned long, unsigned long, unsigned long);
};

구조체랑 file_operations 라는 구조체가 맞지 않는것 같아서

소스코드 부분을

struct file_operations mydrv_fops = {
    NULL,
    NULL,
    mydrv_read,
    mydrv_write,
    NULL,
    NULL,
    NULL,
    NULL,
    mydrv_open,
    NULL,
    mydrv_release,
    NULL,
    NULL,
    NULL,
    NULL,
    NULL,
    NULL,
    NULL
};

이렇게 고치고 해보았지만 ... 역시 warning이 뜨네여 ..

mydrv.c:42: warning: initialization from incompatible pointer type

pointer의 타입이 맞지 않는다고 하는데 .... 저는 이상한점을 찾을수가 없네요.
도움 부탁드립니다 ........