Kernel module is removed successfully although warning message 'not found" - c

Question

Yesterday I installed a very simple kernel module in my embedded Linux system. "hello.ko".
When I install this module to our system, it's normally:
#insmod hello.ko
Initing kernel module
#
#lsmod
hello 638 0 - Live 0xf628f000
But when I remove this kernel module, It can be removed normally but rmmod notice 'hello.ko' not found
# rmmod hello
Cleaning kernel module
rmmod: module 'hello' not found
#lsmod <------------------- already be removed
#
# uname -a
# Linux SWITCH 2.6.32 #8 Thu Jun 23 20:34:48 KST 2016 ppc GNU/Linux
It's very strange. Could anyone explain for me why 'hello.ko' is removed but there's log 'rmmod module not found'?
The following are source code of hello.ko
#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/config.h>
#include <linux/version.h>
#include <linux/types.h>
#include <linux/string.h>
int init_module(void)
{
printk (KERN_EMERG "Initing kernel module\n");
return 0;
}
void cleanup_module(void)
{
printk (KERN_EMERG "Cleaning kernel module\n");
}
MODULE_DESCRIPTION ("Kernel function replacement module");
MODULE_AUTHOR ("DASAN Networks Inc.");
MODULE_LICENSE ("GPL");

Answer 1

You need to add few things in my opinion __init and __exit macros and module_init and module_exit macros, try with:
#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/version.h>
#include <linux/types.h>
#include <linux/string.h>
static int __init init_example(void)
{
printk (KERN_EMERG "Initing kernel module\n");
return 0;
}
static void __exit cleanup_example(void)
{
printk (KERN_EMERG "Cleaning kernel module\n");
}
module_init(init_example);
module_exit(cleanup_example);
MODULE_DESCRIPTION ("Kernel function replacement module");
MODULE_AUTHOR ("DASAN Networks Inc.");
MODULE_LICENSE ("GPL");