make error aliased to undefined symbol devone_init - c

Question

I have just made a driver program, and when I execute make, it said
make error aliased to undefined symbol devone_init
I find many sites and cannot find the same error.Because I am new to
device programing , I am not clear about init_module.
#include <linux/init.h>
#include <linux/module.h>
#include <linux/types.h>
#include <linux/kernel.h>
#include <linux/fs.h>
#include <linux/cdev.h>
#include <linux/sched.h>
#include <asm/current.h>
#include <asm/uaccess.h>
MODULE_LICENCE("Dual BSD/GPL");
#define DRIVER_NAME "devone";
static int devone_devs = 2;
static int devone_major = 0;
module_param(devone_major. uint, 0);
static struct cdev devone_cdev;
static int devone_open(struct inode *inode, struct file *file)
{
printk("%s: major %d minor %d (pid %d)\n", __func__, imajor(inode), iminor(inode), current->pid);
inode->i_private = inode;
file->private_data = file;
printk("i_private=%p private_data=%p\n", inode->i_private, file->private_data);
return 0;
}
static int devone_close(struct inode *inode, struct file *file)
{
printk("%s: major %d minor %d (pid %d)\n", __func__, imajor(inode), iminor(inode), current->pid);
inode->i_private = inode;
file->private_data = file;
printk("i_private=%p private_data=%p\n", inode->i_private, file->private_data);
return 0;
}
struct file_operations devone_fops = {
.open = devone_opens;
.release = devone_close;
}
static int devone_init(void)
{
dev_t dev = MKDEV(devone_major, 0);
int alloc_ret = 0;
int major;
int cdev_err = 0;
alloc_ret = alloc_chrdev_region(&dev, 0, devone_devs, DRIVER_NAME);
if(alloc_ret)
goto error;
devone_major = major = MAJOR(dev);
cdev_init(&devone_cdev, &devone_fops);
devone_cdev.owner = THIS_MODULE;
cdev_err = cdev_add(&devone_cdev, MKDEV(devone_major, 0), devone_devs);
if(cdev_err)
goto error;
printk(KERN_ALERT "%s driver(%d) loaded\n", DRIVER_NAME, major);
return 0;
error:
if(cdev_err == 0)
cdev_del(devone_cdev);
if(alloc_ret == 0)
unregister_chrdev_region(dev, devone_devs);
return -1;
}
static void devone_exit(void)
{
dev_t dev = MKDEV(devone_major, 0);
cdev_del(&devone_cdev);
cdev_del(&devone_cdev);
unregister_chrdev_region(dev, devone_devs);
printk(KERN_ALERT "%s driver unloaded\n", DRIVER_NAME);
}
module_init(devone_init);
module_exit(devone_exit);
here is my makefile.When I add cflags , it returned cflags was changed.
#CFLAGS += -Wall
CFILES = devone.c
obj-m += sample.o
KDIR =/lib/modules/$(shell uname -r)/build
sample-objs := $(CFILES:.c=.o)
all:
$(MAKE) -C $(KDIR) M=$(shell pwd) modules
clean:
rm -rf *.o *.ko *.mod.* *.symvers *.order

Answer 1

There are several minute problems in the code which is preventing it from compilation. Modified code which compiles properly is below. you can compare and find out the diff.
#include <linux/init.h>
#include <linux/module.h>
#include <linux/types.h>
#include <linux/kernel.h>
#include <linux/fs.h>
#include <linux/cdev.h>
#include <linux/sched.h>
#include <asm/current.h>
#include <asm/uaccess.h>
#define DRIVER_NAME "devone"
static int devone_devs = 2;
static int devone_major = 0;
module_param(devone_major, uint, 0);
static struct cdev devone_cdev;
static int devone_open(struct inode *inode, struct file *file)
{
printk("%s: major %d minor %d (pid %d)\n", __func__, imajor(inode), iminor(inode), current->pid);
inode->i_private = inode;
file->private_data = file;
printk("i_private=%p private_data=%p\n", inode->i_private, file->private_data);
return 0;
}
static int devone_close(struct inode *inode, struct file *file)
{
printk("%s: major %d minor %d (pid %d)\n", __func__, imajor(inode), iminor(inode), current->pid);
inode->i_private = inode;
file->private_data = file;
printk("i_private=%p private_data=%p\n", inode->i_private, file->private_data);
return 0;
}
struct file_operations devone_fops = {
.open = devone_open,
.release = devone_close,
};
static int devone_init(void)
{
dev_t dev = MKDEV(devone_major, 0);
int alloc_ret = 0;
int major;
int cdev_err = 0;
alloc_ret = alloc_chrdev_region(&dev, 0, devone_devs, DRIVER_NAME);
if(alloc_ret)
goto error;
devone_major = major = MAJOR(dev);
cdev_init(&devone_cdev, &devone_fops);
devone_cdev.owner = THIS_MODULE;
cdev_err = cdev_add(&devone_cdev, MKDEV(devone_major, 0), devone_devs);
if(cdev_err)
goto error;
printk(KERN_ALERT "%s driver(%d) loaded\n", DRIVER_NAME, major);
return 0;
error:
if(cdev_err == 0)
cdev_del(&devone_cdev);
if(alloc_ret == 0)
unregister_chrdev_region(dev, devone_devs);
return -1;
}
static void devone_exit(void)
{
dev_t dev = MKDEV(devone_major, 0);
cdev_del(&devone_cdev);
cdev_del(&devone_cdev);
unregister_chrdev_region(dev, devone_devs);
printk(KERN_ALERT "%s driver unloaded\n", DRIVER_NAME);
}
module_init(devone_init);
module_exit(devone_exit);
MODULE_LICENSE("Dual BSD/GPL");