On Wed, Jun 2, 2021 at 3:56 PM Johannes Berg <johannes@xxxxxxxxxxxxxxxx> wrote: >>> The only thing I'd be worried about is that different implementations >>> use it for different meanings, but I guess that's not that big a deal? >> >> The spectrum of sane use of the IFLA_PARENT_DEV_NAME attribute by >> various subsystems and (or) drivers will be quite narrow. It should do >> exactly what its name says - identify a parent device. > > Sure, I was more worried there could be multiple interpretations as to > what "a parent device" is, since userspace does nothing but pass a > string in. But we can say it should be a 'struct device' in the kernel. > >> We can not handle the attribute in the common rtnetlink code since >> rtnetlink does not know the HW configuration details. That is why >> IFLA_PARENT_DEV_NAME should be handled by the RTNL ->newlink() >> callback. But after all the processing, the device that is identified >> by the IFLA_PARENT_DEV_NAME attribute should appear in the >> netdev->dev.parent field with help of SET_NETDEV_DEV(). Eventually >> RTNL will be able to fill IFLA_PARENT_DEV_NAME during the netdevs dump >> on its own, taking data from netdev->dev.parent. > > I didn't do that second part, but I guess that makes sense. > > Want to send a follow-up patch to my other patch? I guess you should've > gotten it, but if not the new series is here: > > https://lore.kernel.org/netdev/20210602082840.85828-1-johannes@xxxxxxxxxxxxxxxx/T/#t Yes, I saw the second version of your RFC and even attempted to provide a full picture of why this attribute should be generic. I will send a follow-up series tonight with parent device exporting support and with some usage examples. >> I assume that IFLA_PARENT_DEV_NAME could replace the IFLA_LINK >> attribute usage in such drivers as MBIM and RMNET. But the best way to >> evolve these drivers is to make them WWAN-subsystem-aware using the >> WWAN interface configuration API from your proposal, IMHO. > > Right. -- Sergey
