From mboxrd@z Thu Jan 1 00:00:00 1970 From: Stephen Hemminger Subject: Re: [RFC PATCH 2/3] netdev: kernel-only IFF_HIDDEN netdevice Date: Mon, 9 Apr 2018 16:03:48 -0700 Message-ID: <20180409160348.12f8a6d9@xeon-e3> References: <3bdfc39f-4935-2433-7982-9ce28c3aa166@gmail.com> <54accf73-e6cc-e03f-6a1c-34e1bbd78047@gmail.com> <20180404.133749.1802514210170809419.davem@davemloft.net> <20180407031919.GB11029@lunn.ch> <20180409221523.GH562@lunn.ch> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Cc: Andrew Lunn , David Miller , David Ahern , Jiri Pirko , si-wei liu , "Michael S. Tsirkin" , Alexander Duyck , "Brandeburg, Jesse" , Jakub Kicinski , Jason Wang , "Samudrala, Sridhar" , Netdev , virtualization@lists.linux-foundation.org, virtio-dev@lists.oasis-open.org To: Siwei Liu Return-path: Received: from mail-pl0-f67.google.com ([209.85.160.67]:38770 "EHLO mail-pl0-f67.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751367AbeDIXDv (ORCPT ); Mon, 9 Apr 2018 19:03:51 -0400 Received: by mail-pl0-f67.google.com with SMTP id c7-v6so2867407plr.5 for ; Mon, 09 Apr 2018 16:03:50 -0700 (PDT) In-Reply-To: Sender: netdev-owner@vger.kernel.org List-ID: On Mon, 9 Apr 2018 15:30:42 -0700 Siwei Liu wrote: > On Mon, Apr 9, 2018 at 3:15 PM, Andrew Lunn wrote: > >> No, implementation wise I'd avoid changing the class on the fly. What > >> I'm looking to is a means to add a secondary class or class aliasing > >> mechanism for netdevs that allows mapping for a kernel device > >> namespace (/class/net-kernel) to userspace (/class/net). Imagine > >> creating symlinks between these two namespaces as an analogy. All > >> userspace visible netdevs today will have both a kernel name and a > >> userspace visible name, having one (/class/net) referecing the other > >> (/class/net-kernel) in its own namespace. The newly introduced > >> IFF_AUTO_MANAGED device will have a kernel name only > >> (/class/net-kernel). As a result, the existing applications using > >> /class/net don't break, while we're adding the kernel namespace that > >> allows IFF_AUTO_MANAGED devices which will not be exposed to userspace > >> at all. > > > > My gut feeling is this whole scheme will not fly. You really should be > > talking to GregKH. > > Will do. Before spreading it out loudly I'd run it within netdev to > clarify the need for why not exposing the lower netdevs is critical > for cloud service providers in the face of introducing a new feature, > and we are not hiding anything but exposing it in a way that don't > break existing userspace applications while introducing feature is > possible with the limitation of keeping old userspace still. > > > > > Anyway, please remember that IFF_AUTO_MANAGED will need to be dynamic. > > A device can start out as a normal device, and will change to being > > automatic later, when the user on top of it probes. > > Sure. In whatever form it's still a netdev, and changing the namespace > should be more dynamic than changing the class. > > Thanks a lot, > -Siwei > > > > > Andrew Also, remember for netdev's /sys is really a third class API. The primary API's are netlink and ioctl. Also why not use existing network namespaces rather than inventing a new abstraction?