kernel module problem.

[Kamal Deep Dham <kamaldeep.dham@xxxxxxxxx>]

Hi ,

I have written a small kernel module to learn the basics of it.

=======================================================
#include <linux/module.h>
#include <linux/netdevice.h>
int my_ioctl(struct net_device *dev, struct ifreq *ifr,int cmd);
int my_open(struct net_device *dev);
int my_init(struct net_device *dev)
{
        if(dev == NULL)
        {
                printk("dev = null\n");
        }

        dev->open = my_open;
        dev->do_ioctl = my_ioctl;
        printk("my_init() called\n");
        return 0;
}
int my_ioctl(struct net_device *dev, struct ifreq *ifr,int cmd)
{
        printk("my_ioctl() called witih cmd = %d\n",cmd);
        return 0;
}
int my_open(struct net_device *dev)
{
        printk("my_open() called\n");
        return 1;
}
static struct net_device myDev = {
  "kamal\0 ",
  0, 0, 0, 0,
  0, 0,
  0, 0, 0,
  NULL, my_init
};
int init_module(void)
{
        int err;
        printk("init_module() called\n");
        if(dev_get_by_name(myDev.name)==NULL)
        {
                err  = register_netdev(&myDev);
                if (err) printk("Error Message ::%d\n",err);
        }
        else
        {
                printk("Dev Already Exist\n");
        }
        return 0;
}
void cleanup_module(void)
{
        unregister_netdev(&myDev);
        printk("cleanup_module() called.\n");
}
====================================================
I am trying to call the my_ioctl() function through SIOCDEVPRIVATE ioctl
command
from user space.  My user space program looks like this:

=====================================================
#include <stdio.h>
#include <string.h>
#include<sys/ioctl.h>
#include<sys/types.h>
#include<sys/socket.h>
#include<linux/netdevice.h>
#include<stdlib.h>
#include <errno.h>
#define LA_COMMAND  SIOCDEVPRIVATE+2
int main()
{
        int s,err;
        int Arg=100;
        struct ifreq    IfReq;
        s=socket(AF_INET, SOCK_STREAM, 0);
        /* s = socket(AF_INET, SOCK_RAW, 255); */
        if(s<0)
        {
                printf("Unable To Open The Socket\n");
                return 0;
        }
        strcpy(IfReq.ifr_name,"kamal");
        IfReq.ifr_data = (void*)&Arg;
        err = ioctl(s,LA_COMMAND, &IfReq);
        if(err < 0)
        {
                printf("Error Occured :: %d\n",errno);
                perror("");
                return 0;
        }
}
====================================================

But I am getting the following error after its execution:

#
Error Occured :: 95
Operation not supported


In file /usr/src/linux/net/core/dev.c

static int dev_ifsioc(struct ifreq *ifr, unsigned int cmd)
{
.
.
.
.
.
.
.

         default:
                        if ((cmd >= SIOCDEVPRIVATE &&
                            cmd <= SIOCDEVPRIVATE + 15) ||
                            cmd == SIOCETHTOOL) {

                                if (dev->do_ioctl) {

                                        if (!netif_device_present(dev))
                                                return -ENODEV;
                                        return dev->do_ioctl(dev, ifr,
cmd);
                                }
                                return -EOPNOTSUPP;    ==>> error is
returnded from here
        }

.
.


}



I found that in default case, dev->do_ioctl is comming NULL and hence
EOPNOTSUPP
error is returned.



can anyone have idea why this error is there ??

-Kamal

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