From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jiri Pirko Subject: Re: [PATCH net-next v2] ipv4: fib: Replay events when registering FIB notifier Date: Wed, 2 Nov 2016 14:48:45 +0100 Message-ID: <20161102134845.GI1713@nanopsycho.orion> References: <1477948427-9189-1-git-send-email-idosch@idosch.org> <1477949046.7065.320.camel@edumazet-glaptop3.roam.corp.google.com> <20161031225737.7nfoy4ka3ydzhptq@splinter> <1478009999.7065.334.camel@edumazet-glaptop3.roam.corp.google.com> <5818B146.20209@cumulusnetworks.com> <20161101170345.pq2ewecw35mrurkp@splinter> <58194BD6.5040406@cumulusnetworks.com> <20161102072032.GA1713@nanopsycho.orion> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: Ido Schimmel , Eric Dumazet , "netdev@vger.kernel.org" , "davem@davemloft.net" , Jiri Pirko , mlxsw , David Ahern , Nikolay Aleksandrov , Andy Gospodarek , Vivien Didelot , Andrew Lunn , Florian Fainelli , alexander.h.duyck@intel.com, Alexey Kuznetsov , James Morris , Hideaki YOSHIFUJI , Patrick McHardy , Ido Schimmel To: Roopa Prabhu Return-path: Received: from mail-wm0-f65.google.com ([74.125.82.65]:35691 "EHLO mail-wm0-f65.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754259AbcKBNss (ORCPT ); Wed, 2 Nov 2016 09:48:48 -0400 Received: by mail-wm0-f65.google.com with SMTP id 68so3174827wmz.2 for ; Wed, 02 Nov 2016 06:48:48 -0700 (PDT) Content-Disposition: inline In-Reply-To: Sender: netdev-owner@vger.kernel.org List-ID: Wed, Nov 02, 2016 at 02:29:40PM CET, roopa@cumulusnetworks.com wrote: >On Wed, Nov 2, 2016 at 12:20 AM, Jiri Pirko wrote: >> Wed, Nov 02, 2016 at 03:13:42AM CET, roopa@cumulusnetworks.com wrote: >>> >[snip] > >>>I understand..but, if you are adding some core infrastructure for switchdev ..it cannot be >>>based on the number of simple use-cases or data you have today. >>> >>>I won't be surprised if tomorrow other switch drivers have a case where they need to >>>reset the hw routing table state and reprogram all routes again. Re-registering the notifier to just >>>get the routing state of the kernel will not scale. For the long term, since the driver does not maintain a cache, >> >> Driver (mlxsw, rocker) maintain a cache. So I'm not sure why you say >> otherwise. >> >> >>>a pull api with efficient use of rtnl will be useful for other such cases as well. >> >> How do you imagine this "pull API" should look like? > > >Just like you already have added fib notifiers to parallel fib netlink >notifications, the pull API is a parallel to 'netlink dump'. >Is my imagination too wild ? :) Perhaps I'm slow, but I don't understand what you mean. > > >> >> >>> >>> >>>If you don't want to get to the complexity of a new api right away because of the >>>simple case of management interface routes you have, Can your driver register the notifier early ? >>>(I am sure you have probably already thought about this) >> >> Register early? What it would resolve? I must be missing something. We >> register as early as possible. But the thing is, we cannot register >> in a past. And that is what this patch resolves. > >sure, you must be having a valid problem then. I was just curious why >your driver is not up and initialized before any of the addresses or >routes get configured in the system (even on a management port). Ours If you unload the module and load it again for example. This is a valid usecase. >does. But i agree there can be races and you cannot always guarantee >(I was just responding to ido's comment about adding complexity for a >small problem he has to solve for management routes). Our driver does >a pull before it starts. This helps when we want to reset the hardware >routing table state too. Can you point me to you driver in the tree? I would like to see how you do "the pull". > > >But, my point was, when you are defining an API, you cannot quantify >the 'past' to be just the very 'close past' or 'the past is just the >management routes that were added' . Tomorrow the 'past' can be the >full routing table if you need to reset the hardware state. Sure.