From mboxrd@z Thu Jan 1 00:00:00 1970 From: Thomas Graf Subject: Re: the future of ethtool Date: Mon, 15 Nov 2010 18:33:35 -0500 Message-ID: <20101115233335.GB24292@canuck.infradead.org> References: <4CE18CEA.5080502@garzik.org> <1289852326.2586.32.camel@bwh-desktop> <20101115124428.7b857ccb@nehalam> <1289855642.2586.38.camel@bwh-desktop> <20101115131453.16958d68@nehalam> <1289857936.2586.51.camel@bwh-desktop> <4CE1B8FD.3000007@garzik.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: Ben Hutchings , Stephen Hemminger , NetDev , David Miller To: Jeff Garzik Return-path: Received: from canuck.infradead.org ([134.117.69.58]:40114 "EHLO canuck.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752996Ab0KOXdn (ORCPT ); Mon, 15 Nov 2010 18:33:43 -0500 Content-Disposition: inline In-Reply-To: <4CE1B8FD.3000007@garzik.org> Sender: netdev-owner@vger.kernel.org List-ID: On Mon, Nov 15, 2010 at 05:49:33PM -0500, Jeff Garzik wrote: > s/only// I don't think Stephen is suggesting sending _some_ ops > through netlink and others through old-ioctl. That's just silly. > Any new netlink interface should transit all existing ETHTOOL_xxx > commands/structures. > > But presumably, one would have the ability to send multiple > ETHTOOL_xxx bundled together into a single netlink transaction, > facilitating the kernel's calling of struct ethtool_ops' > ->begin() > ... first operation specified by userspace via netlink ... > ... second operation specified by userspace via netlink ... > ... etc. > ->end() > > The underlying struct ethtool_ops remains unchanged; you're only > changing the transit method. > > Thus, the ethtool userspace utility would switch entirely to > netlink, while the ioctl processing code remains for binary > compatibility. > > Or... ethtool userspace utility could remain unchanged, and a new > 'nictool' utility provides the same features but with (a) a new CLI > and (b) exclusively uses netlink rather than ioctl. I actually have code for this including userspace. I never submitted it because I wasn't confident it is the way to go since it literally duplicates all ethtool code in the kernel. There is one major problem with bundling multiple requests though. If one change request fails but other changes have been committed already we can't really undo them without causing lots of races. We have to leave the device in a somewhat inconsistent state. It's even difficult to tell what has been comitted and what hasn't. It also makes error reporting more difficult as a -ERANGE error code could apply to any of the values to be changed. I tried to solve this by splitting the validate/change operation and thus be able to validate all requests before starting to commit them. This would mean changing all drivers though which I wasn't willing to do. I can clean up what I have and submit it so we have something to start with.