Data is not written into /proc file - c

Question

I wrote a kernel module which creates a /proc file. I also wrote an user space code which writes into the file and I fetch that written data to my module using "copy_from_user" method and print in the kernel logs.
The data is written successfully on the logs but when I open the proc file in an editor then its blank.
Can anyone explain me why this is so?
The user space code is
#include<fcntl.h>
main()
{
int fd=open("/proc/MY_PROC_FILE", O_RDWR);
write(fd, "linux is awesome", 16);
return 0;
}
The module is
int open_callback(struct inode *p, struct file *q)
{
printk(KERN_ALERT "open callback\n");
return 0;
}
ssize_t write_callback(struct file *p, const char __user *buffer, size_t len, loff_t *s)
{
printk(KERN_ALERT "write callback\n");
char msg[256];
copy_from_user(msg, buffer, len);
printk("%s\n", msg);
return 0;
}
static struct proc_dir_entry *my_proc_entry;
static struct file_operations fs={
.open=open_callback,
.read=read_callback,
.write=write_callback,
.release=release_callback
};
static int start(void)
{
printk(KERN_ALERT "proc module registered\n");
my_proc_entry=proc_create(file_name, 0, NULL, &fs);
if(my_proc_entry==NULL)
{
printk(KERN_ALERT "os error\n");
return -ENOMEM;
}
return 0;
}
static void stop(void)
{
remove_proc_entry(file_name, NULL);
printk(KERN_ALERT "proc module unregistered\n");
}
module_init(start);
module_exit(stop);
MODULE_LICENSE("GPL");
Thanks in advance for any help

Answer 1

You did not implemented read_callback()
when you gona read that proc file then that read_callback() will be called. Here you need to write code to write back(Using copy_to_user()) what was written earlier in write_callback() callback.
First you need to store what was written by user in write_callback() in some global memory for kernel space then on only you can write that back in read_callback()
This is best example of what you want to do. http://www.makelinux.net/books/lkmpg/x810