I am trying to have a communication between kernel and user space...The code i am using is as follows

//************KERNEL SPACE CODE***********************
#include <linux/config.h>
#include <linux/module.h>
#include <linux/kernel.h>
#include <sys/socket.h>
#include <linux/netlink.h>
#include <linux/init.h>

MODULE_LICENSE("GPL");
#define NETLINK_TEST 17
#define wake_up_interruptible(x)
void nl_data_ready (struct sock *sk, int len);
static int debug = 0;
struct sock *netlink_kernel_create(int unit, void (*input)(struct sock *sk, int len));
module_param(debug, int, 0);
MODULE_PARM_DESC(debug, "Debug information (default 0)");

static struct sock *nl_sk = NULL
void nl_data_ready (struct sock *sk, int len)
{
wake_up_interruptible(sk->sk_sleep);
}

void netlink_test()
{
struct sk_buff *skb = NULL;
struct nlmsghdr *nlh = NULL;
int err;
u32 pid;

nl_sk = netlink_kernel_create(NETLINK_TEST,nl_data_ready);
skb = skb_recv_datagram(nl_sk, 0, 0, &err);

nlh = (struct nlmsghdr *)skb->data;
printk(KERN_INFO "%s: received netlink message payload: %s\n", __FUNCTION__, NLMSG_DATA(nlh));

pid = nlh->nlmsg_pid;
//NETLINK_CB(skb).groups = 0;
NETLINK_CB(skb).pid = 0;
NETLINK_CB(skb).dst_pid = pid;
//NETLINK_CB(skb).dst_groups = 0;
netlink_unicast(nl_sk, skb, pid, MSG_DONTWAIT);
//sock_release(nl_sk->sk_socket);
}

static int __init my_module_init(void)
{
printk(KERN_INFO "Initializing Netlink Socket");
netlink_test();
return 0;
}

static void __exit my_module_exit(void)
{
printk(KERN_INFO "Goodbye");
}

module_init(my_module_init);
module_exit(my_module_exit);
//****************************************************
while compiling the make file i get the error as
/root/socket/sirk.c:13: error: conflicting types for `netlink_kernel_create'
include/linux/netlink.h:130: error: previous declaration of `netlink_kernel_create'
/root/socket/sirk.c:18: error: syntax error before "void"

can anybody tell me the solution for these errors

Pay attention at red characters:

BTW, What is output of command "uname -r" at your box???

Good luck,
Giang Hu.

As the error message states netlink_kernel_create declaration is contradicting

netlink_kernel_create available in netlink.h
as the following signature
struct sock *netlink_kernel_create(int unit, void (*input)(struct sock *sk, int len));

you have used,
sock *netlink_kernel_create(int unit, void (*input)(struct sock *sk, int len));

with an undefined datatype sock

hope this helps!!!