ioctl.c

static int rwbuf_ioctl(struct inode *node, struct file * filep, unsigned int cmd, unsigned long arg)
{
	if(cmd==RWBUF_CLEAR)
	{
		rwlen = 0;
		printk(KERN_ALERT "rwbuf in kernel zero-ed\n");
		return 0;
	}
	else if(cmd==RWBUF_LENGTH)
	{
		printk(KERN_ALERT "length of buffer\n");
		return rwlen;
	}
	else if(cmd==RWBUF_NUM)
	{
		printk(KERN_ALERT "num of writing\n");
		return writenum;
	}
	return 0;
}