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SubjectRe: [PATCH net-next v6 2/5] net/lapb: support netdev events
On 2020-11-25 22:49, Jakub Kicinski wrote:
> On Tue, 24 Nov 2020 10:39:35 +0100 Martin Schiller wrote:
>> 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: Martin Schiller <ms@dev.tdt.de>
>
>> +/* 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) {
>
> Flip condition, save indentation.
>
> if (dev->type != ARPHRD_X25)
> return NOTIFY_DONE;
>
> You can also pull out of all the cases:
>
> lapb = lapb_devtostruct(dev);
> if (!lapb)
> return NOTIFY_DONE;
>
> right?
>
>> + switch (event) {
>> + case NETDEV_UP:
>> + lapb_dbg(0, "(%p) Interface up: %s\n", dev,
>> + dev->name);
>> +
>> + if (netif_carrier_ok(dev)) {
>> + lapb = lapb_devtostruct(dev);
>> + if (!lapb)
>> + break;
>
>> static int __init lapb_init(void)
>> {
>> + register_netdevice_notifier(&lapb_dev_notifier);
>
> This can fail, so:
>
> return register_netdevice_notifier(&lapb_dev_notifier);
>
>> return 0;
>> }
>>
>> 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>");

Thanks for your hints! I will send an update.

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