From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jiri Pirko Subject: Re: [patch net-next v4 00/10] net: sched: allow qdiscs to share filter block instances Date: Mon, 25 Dec 2017 11:23:46 +0100 Message-ID: <20171225102346.GB1885@nanopsycho> References: <20171223155436.9014-1-jiri@resnulli.us> <20171224071956.GA1883@nanopsycho> <780a80d0-9384-ae34-4cab-3070b004b64e@gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: netdev@vger.kernel.org, davem@davemloft.net, jhs@mojatatu.com, xiyou.wangcong@gmail.com, mlxsw@mellanox.com, andrew@lunn.ch, vivien.didelot@savoirfairelinux.com, f.fainelli@gmail.com, michael.chan@broadcom.com, ganeshgr@chelsio.com, saeedm@mellanox.com, matanb@mellanox.com, leonro@mellanox.com, idosch@mellanox.com, jakub.kicinski@netronome.com, simon.horman@netronome.com, pieter.jansenvanvuuren@netronome.com, john.hurley@netronome.com, alexander.h.duyck@intel.com, ogerlitz@mellanox.com, john.fastabend@gmail.com, daniel@iogearbox.net To: David Ahern Return-path: Received: from mail-wm0-f68.google.com ([74.125.82.68]:37875 "EHLO mail-wm0-f68.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750811AbdLYKXt (ORCPT ); Mon, 25 Dec 2017 05:23:49 -0500 Received: by mail-wm0-f68.google.com with SMTP id f140so31313201wmd.2 for ; Mon, 25 Dec 2017 02:23:48 -0800 (PST) Content-Disposition: inline In-Reply-To: <780a80d0-9384-ae34-4cab-3070b004b64e@gmail.com> Sender: netdev-owner@vger.kernel.org List-ID: Sun, Dec 24, 2017 at 05:25:41PM CET, dsahern@gmail.com wrote: >On 12/24/17 1:19 AM, Jiri Pirko wrote: >> Sun, Dec 24, 2017 at 02:54:47AM CET, dsahern@gmail.com wrote: >>> On 12/23/17 9:54 AM, Jiri Pirko wrote: >>>> So back to the example. First, we create 2 qdiscs. Both will share >>>> block number 22. "22" is just an identification. If we don't pass any >>>> block number, a new one will be generated by kernel: >>>> >>>> $ tc qdisc add dev ens7 ingress block 22 >>>> ^^^^^^^^ >>>> $ tc qdisc add dev ens8 ingress block 22 >>>> ^^^^^^^^ >>>> >>>> Now if we list the qdiscs, we will see the block index in the output: >>>> >>>> $ tc qdisc >>>> qdisc ingress ffff: dev ens7 parent ffff:fff1 block 22 >>>> qdisc ingress ffff: dev ens8 parent ffff:fff1 block 22 >>>> >>>> To make is more visual, the situation looks like this: >>>> >>>> ens7 ingress qdisc ens7 ingress qdisc >>>> | | >>>> | | >>>> +----------> block 22 <----------+ >>>> >>>> Unlimited number of qdiscs may share the same block. >>>> >>>> Now we can add filter to any of qdiscs sharing the same block: >>>> >>>> $ tc filter add dev ens7 ingress protocol ip pref 25 flower dst_ip 192.168.0.0/16 action drop >>> >>> >>> Allowing config of a shared block through any qdisc that references it >>> is akin to me allowing nexthop objects to be manipulated by any route >>> that references it -- sure, it could be done but causes a lot surprises >>> to the user. >>> >>> You are adding a new tc object -- a shared block. Why the resistance to >>> creating a proper API for managing it? >> >> Again, no resistance, I said many times it would be done as a follow-up. >> But as an api already exists, it has to continue to work. Or do you >> suggest it should stop working? That, I don't agree with. >> > >That is exactly what I am saying - principle of least surprise. The new >object brings its own API and can only be modified using the new API. >The scheme above can and will surprise users. You are thinking like a tc >developer, someone intimately familiar with the code, and not like an >ordinary user of this new feature. Breaking exising tools is newer good. Note that not only about filter add/del iface but also dump and notifications. I agree to extend the api for the "block handle", sure, but the existing api should continue to work.