Messages in this thread | | | Date | Mon, 23 Nov 2020 11:38:34 +0100 | From | Martin Schiller <> | Subject | Re: [PATCH net-next v4 2/5] net/lapb: support netdev events |
| |
On 2020-11-23 11:08, Xie He wrote: > On Mon, Nov 23, 2020 at 1:36 AM Xie He <xie.he.0141@gmail.com> wrote: >> >> Some drivers don't support carrier status and will never change it. >> Their carrier status will always be UP. There will not be a >> NETDEV_CHANGE event.
Well, one could argue that we would have to repair these drivers, but I don't think that will get us anywhere.
From this point of view it will be the best to handle the NETDEV_UP in the lapb event handler and establish the link analog to the NETDEV_CHANGE event if the carrier is UP.
>> >> lapbether doesn't change carrier status. I also have my own virtual >> HDLC WAN driver (for testing) which also doesn't change carrier >> status. >> >> I just tested with lapbether. When I bring up the interface, there >> will only be NETDEV_PRE_UP and then NETDEV_UP. There will not be >> NETDEV_CHANGE. The carrier status is alway UP. >> >> I haven't tested whether a device can receive NETDEV_CHANGE when it is >> down. It's possible for a device driver to call netif_carrier_on when >> the interface is down. Do you know what will happen if a device driver >> calls netif_carrier_on when the interface is down? > > I just did a test on lapbether and saw there would be no NETDEV_CHANGE > event when the netif is down, even if netif_carrier_on/off is called. > So we can rest assured of this part.
| |