On Wed, Sep 15, 2010 at 5:39 PM, Tayade, Nilesh <Nilesh.Tayade@xxxxxxxxxxxx> wrote:
Can't it be because you are using size = 1byte in copy_from_user? Make it 'count'.
After your suggestion I tried changing
---------------------------------------------------------
#include <linux/init.h>
#include <linux/module.h>
#include <linux/kernel.h> /* printk() */
#include <linux/slab.h> /* kmalloc() */
#include <linux/fs.h> /* everything... */
#include <linux/errno.h> /* error codes */
#include <linux/types.h> /* size_t */
#include <linux/proc_fs.h>
#include <linux/fcntl.h> /* O_ACCMODE */
#include <asm/system.h> /* cli(), *_flags */
#include <asm/uaccess.h> /* copy_from/to_user */
/* Declaration of memory.c functions */
int bond_open(struct inode *inode, struct file *filp) { return 0;};
int bond_release(struct inode *inode, struct file *filp){ return 0;};
ssize_t bond_read(struct file *filp, char *buf, size_t count, loff_t *f_pos)
{
/* Transfering data to user space */
copy_to_user(buf,bond_buffer,1);
/* Changing reading position as best suits */
if (*f_pos == 0) {
*f_pos+=1;
return 1;
} else {
return 0;
}
};
ssize_t bond_write(struct file *filp, char *buf, size_t count, loff_t *f_pos)
{
char *tmp;
tmp=buf+count-1;
copy_from_user(bond_buffer,tmp,1);
return 1;
} ;
void bond_exit(void);
int bond_init(void);
/* Structure that declares the usual file */
/* access functions */
struct file_operations bond_fops = {
read: bond_read,
write: bond_write,
open: bond_open,
release: bond_release
};
/* Global variables of the driver */
/* Major number */
int bond_major = 60;
/* Buffer to store data */
char *bond_buffer;
I am not sure if the above statement I wrote is supposed to be written like that only.
static int bond_init(void) {
printk("<1> Hello bond new driver!\n");
int result;
/* Registering device */
result = register_chrdev(bond_major, "bond", &bond_fops);
if (result < 0) {
printk(
"<1>memory: cannot obtain major number %d\n", bond_major);
return result;
}
/* Allocating memory for the buffer */
bond_buffer = kmalloc(1, GFP_KERNEL);
kmalloc here I passed on 10 (and compiled and checked there were same results no change)
if any other changes let me know I will try.
if (!bond_buffer) {
result = -ENOMEM;
goto fail;
}
memset(bond_buffer, 0, 1);
Changed the value of 1 to 10 here recompiled (did not worked same problem)
Are you referring to this area to be changed.
printk("<1>Inserting bond module\n");
return 0;
fail:
bond_exit();
return result;
return 0;
}
static void bond_exit(void) {
printk("<1> Bye, bond world\n");
/* Freeing the major number */
unregister_chrdev(bond_major, "bond");
/* Freeing buffer memory */
if (bond_buffer) {
kfree(bond_buffer);
}
printk("<1>Removing bond module\n");
}
module_init(bond_init);
module_exit(bond_exit);
I am not having any clue to any of above so let me know what you or some one reading this thread thinks about it.
