Commit a4989fa9 authored by Martin Schiller's avatar Martin Schiller Committed by Jakub Kicinski
Browse files

net/lapb: support netdev events 



This patch allows layer2 (LAPB) to react to netdev events itself and
avoids the detour via layer3 (X.25).

1. Establish layer2 on NETDEV_UP events, if the carrier is already up.

2. Call lapb_disconnect_request() on NETDEV_GOING_DOWN events to signal
   the peer that the connection will go down.
   (Only when the carrier is up.)

3. When a NETDEV_DOWN event occur, clear all queues, enter state
   LAPB_STATE_0 and stop all timers.

4. The NETDEV_CHANGE event makes it possible to handle carrier loss and
   detection.

   In case of Carrier Loss, clear all queues, enter state LAPB_STATE_0
   and stop all timers.

   In case of Carrier Detection, we start timer t1 on a DCE interface,
   and on a DTE interface we change to state LAPB_STATE_1 and start
   sending SABM(E).

Signed-off-by: default avatarMartin Schiller <ms@dev.tdt.de>
Acked-by: default avatarXie He <xie.he.0141@gmail.com>
Signed-off-by: default avatarJakub Kicinski <kuba@kernel.org>
parent 7eed751b

net/lapb/lapb_iface.c

+81 −1
Original line number Diff line number Diff line
@@ -418,14 +418,94 @@ int lapb_data_transmit(struct lapb_cb *lapb, struct sk_buff *skb) 
	return used;

}



/* Handle device status changes. */

static int lapb_device_event(struct notifier_block *this, unsigned long event,

			     void *ptr)

{

	struct net_device *dev = netdev_notifier_info_to_dev(ptr);

	struct lapb_cb *lapb;



	if (!net_eq(dev_net(dev), &init_net))

		return NOTIFY_DONE;



	if (dev->type != ARPHRD_X25)

		return NOTIFY_DONE;



	lapb = lapb_devtostruct(dev);

	if (!lapb)

		return NOTIFY_DONE;



	switch (event) {

	case NETDEV_UP:

		lapb_dbg(0, "(%p) Interface up: %s\n", dev, dev->name);



		if (netif_carrier_ok(dev)) {

			lapb_dbg(0, "(%p): Carrier is already up: %s\n", dev,

				 dev->name);

			if (lapb->mode & LAPB_DCE) {

				lapb_start_t1timer(lapb);

			} else {

				if (lapb->state == LAPB_STATE_0) {

					lapb->state = LAPB_STATE_1;

					lapb_establish_data_link(lapb);

				}

			}

		}

		break;

	case NETDEV_GOING_DOWN:

		if (netif_carrier_ok(dev))

			lapb_disconnect_request(dev);

		break;

	case NETDEV_DOWN:

		lapb_dbg(0, "(%p) Interface down: %s\n", dev, dev->name);

		lapb_dbg(0, "(%p) S%d -> S0\n", dev, lapb->state);

		lapb_clear_queues(lapb);

		lapb->state = LAPB_STATE_0;

		lapb->n2count   = 0;

		lapb_stop_t1timer(lapb);

		lapb_stop_t2timer(lapb);

		break;

	case NETDEV_CHANGE:

		if (netif_carrier_ok(dev)) {

			lapb_dbg(0, "(%p): Carrier detected: %s\n", dev,

				 dev->name);

			if (lapb->mode & LAPB_DCE) {

				lapb_start_t1timer(lapb);

			} else {

				if (lapb->state == LAPB_STATE_0) {

					lapb->state = LAPB_STATE_1;

					lapb_establish_data_link(lapb);

				}

			}

		} else {

			lapb_dbg(0, "(%p) Carrier lost: %s\n", dev, dev->name);

			lapb_dbg(0, "(%p) S%d -> S0\n", dev, lapb->state);

			lapb_clear_queues(lapb);

			lapb->state = LAPB_STATE_0;

			lapb->n2count   = 0;

			lapb_stop_t1timer(lapb);

			lapb_stop_t2timer(lapb);

		}

		break;

	}



	return NOTIFY_DONE;

}



static struct notifier_block lapb_dev_notifier = {

	.notifier_call = lapb_device_event,

};



static int __init lapb_init(void)

{

	return 0;

	return register_netdevice_notifier(&lapb_dev_notifier);

}



static void __exit lapb_exit(void)

{

	WARN_ON(!list_empty(&lapb_list));



	unregister_netdevice_notifier(&lapb_dev_notifier);

}



MODULE_AUTHOR("Jonathan Naylor <g4klx@g4klx.demon.co.uk>");

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