/* Linux network device status watcher

   (C) 2002 Stefan Rompf
   GPL Version 2 applies

   compile with something like
    gcc -c -DMODULE -D__KERNEL__ -O2 dev_watch.c
*/

#include <linux/sched.h>
#include <linux/config.h>
#include <linux/module.h>
#include <linux/netdevice.h>
#include <linux/if.h>
#include <linux/rtnetlink.h>

static volatile pid_t me;

static volatile int running = 1;

static int devwatcher(void *dummy)
{
        struct net_device *dev;
	
	daemonize();
	strcpy(current->comm, "devwatchd");

	while(running) {
		rtnl_lock();
		for (dev=dev_base; dev; dev = dev->next) {

			/* State of netif_carrier_ok() is reflected
			   into dev_flags by this loop, and a netlink
			   message is omitted whenever the state
			   changes */

			if (dev->flags & IFF_RUNNING) {
				if (!netif_carrier_ok(dev)) {
					write_lock(&dev_base_lock);
					dev->flags &= ~IFF_RUNNING;
					write_unlock(&dev_base_lock);
					netdev_state_change(dev);
				}
			} else {
				if (netif_carrier_ok(dev)) {
					write_lock(&dev_base_lock);
					dev->flags |= IFF_RUNNING;
					write_unlock(&dev_base_lock);
					netdev_state_change(dev);
				}
			}
		}
		rtnl_unlock();

		set_current_state(TASK_INTERRUPTIBLE);
		schedule_timeout(HZ);
	}
		

	me = 0;
	return 0;
}

static int __init devwatch_init(void) {
	me = kernel_thread(devwatcher, NULL, CLONE_FS | CLONE_FILES | CLONE_SIGNAL);

	if (!me) return 1;

	return 0;
}


static void __exit devwatch_cleanup(void) {
	running = 0;
	while(me) schedule();
}


EXPORT_NO_SYMBOLS;

module_init(devwatch_init);
module_exit(devwatch_cleanup);