Regarding the NETLINK-socket Program for OSK5912

["Azhar Mr." <shaik.azharuddin@yahoo.co.in>]

Hi,
I want to have communication between kernel module and
user space application. For communication I am using
netlink sockets. I have successfully compiled user
space application. But unable to compile kernel
module. :-(. It is giving error as 'Dereferencing
pointer to incomplete type'

The psuedocode is as follows for kernel module 

#include <sys/socket.h>
#include <linux/netlink.h>

#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/mm.h>
#include <linux/slab.h>
#include <linux/fs.h>
#include <linux/sched.h>
#include <asm/uaccess.h>
#include <linux/poll.h>
#include <linux/interrupt.h>
#include <linux/wait.h>
#include <linux/delay.h>
#include <linux/time.h>
#include <linux/vmalloc.h>
#include <asm/io.h>

#include <linux/init.h>
#include <linux/list.h>
#include <linux/platform_device.h>
#include <linux/timer.h>
#include <linux/err.h>
#include <linux/input.h>
#include <asm/arch/hardware.h>
#include <asm/arch/gpio.h>
#include <asm/arch/irqs.h>
#include <asm/arch/mux.h>
#include <asm/arch/board.h>

#define MAX_PAYLOAD 1024
/* Define any of the valid GPIO pins as LED_GPIO */
#define LED_GPIO 7

/* Defines the value written to the pin defined as
LED_GPIO */
#define LED_STATUS 1

MODULE_LICENSE("Dual BSD/GPL");

// Note: Debug is not implemented
static int debug = 0;

module_param(debug, int, 0);
MODULE_PARM_DESC(debug, "Debug information (default
0)");

static struct sock *nl_sk = NULL;

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

static 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 init_module(void)
{
	/* requesting for LED_GPIO */
	if(omap_request_gpio(LED_GPIO)<0)
	{
	printk("[ERROR]: Failed in allocating the requested
GPIO Pin \n");
		return -1;
	}
	
	/* setting LED_GPIO as output pin */
	omap_set_gpio_direction(LED_GPIO,0);

	/* writing to LED_GPIO the value of LED_STATUS */
	omap_set_gpio_dataout(LED_GPIO,1);

	/* printing the value of LED_GPIO pin */
	printk("value of pin # %d =
%d\n",LED_GPIO,omap_get_gpio_datain(LED_GPIO));

	printk("\n [START] : netlink_test");
	netlink_test();
	printk("\n [END] : netlink_test");
	
	return 0;
}

static void __exit cleanup_module(void)
{
	omap_free_gpio(LED_GPIO);	
	printk("[SUCCESS]: LED_GLOW Module unregistered
successfull.\n");
}

After compiling the kernel module I am getting the
following errors



drivers/leds/leds-glow.c:1:24: sys/socket.h: No such
file or directory
drivers/leds/leds-glow.c: In function `nl_data_ready':
drivers/leds/leds-glow.c:53: error: dereferencing
pointer to incomplete type
drivers/leds/leds-glow.c: At top level:
drivers/leds/leds-glow.c:57: warning: function
declaration isn't a prototype
drivers/leds/leds-glow.c: In function `netlink_test':
drivers/leds/leds-glow.c:63: error: `NETLINK_TEST'
undeclared (first use in this function)
drivers/leds/leds-glow.c:63: error: (Each undeclared
identifier is reported only once
drivers/leds/leds-glow.c:63: error: for each function
it appears in.)
drivers/leds/leds-glow.c:63: warning: passing arg 2 of
`netlink_kernel_create' makes integer from pointer
without a cast
drivers/leds/leds-glow.c:63: error: too few arguments
to function `netlink_kernel_create'
drivers/leds/leds-glow.c:67: warning: char format,
void arg (arg 3)
drivers/leds/leds-glow.c:70: error: structure has no
member named `groups'
drivers/leds/leds-glow.c:72: error: structure has no
member named `dst_pid'
drivers/leds/leds-glow.c:73: error: structure has no
member named `dst_groups'
drivers/leds/leds-glow.c:75: error: dereferencing
pointer to incomplete type
drivers/leds/leds-glow.c: At top level:
drivers/leds/leds-glow.c:79: warning: static
declaration for `init_module' follows non-static
drivers/leds/leds-glow.c:104: warning: static
declaration for `cleanup_module' follows
non-staticdrivers/leds/leds-glow.c:79: warning:
`init_module' defined but not used
drivers/leds/leds-glow.c:104: warning:
`cleanup_module' defined but not used
make[2]: *** [drivers/leds/leds-glow.o] Error 1
make[1]: *** [drivers/leds] Error 2
make: *** [drivers] Error 2

Please Help.

Regards
Azharuddin


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