linux驱动模块编译问题

我的驱动的ffile_operations dev_fops 如下：
static struct file_operations dev_fops = {
    .owner    =THIS_MODULE,
    .read  =    buttons_read,
    .write =    button_write,//91行
    .ioctl    =sbc2440_leds_ioctl,
};

write函数原型：static ssize_t button_write(struct file *file,char __user *buf,size_t count,loff_t *f_pos)

编译的时候出现如下警告：

drivers/char/getin.c:91: warning: initialization from incompatible pointer type

91行要怎么写呢？


模块能编译出来，我感觉有警告心里就不踏实一样，测试驱动也没有问题，

在我用的内核源代码的include/linux/fs.h里有

复制代码 struct file_operations {         struct module *owner;         loff_t (*llseek) (struct file *, loff_t, int);         ssize_t (*read) (struct file *, char __user *, size_t, loff_t *);         ssize_t (*write) (struct file *, const char __user *, size_t, loff_t *);         ssize_t (*aio_read) (struct kiocb *, const struct iovec *, unsigned long, loff_t); ...

所以驱动里的write()函数严格的声明可以写成

复制代码 static ssize_t button_write(struct file *file,const char __user *buf,size_t count,loff_t *f_pos);

不过你可以放心，这个不影响驱动的功能，只是编译器严格检查函数原型造成的警告而已