From mboxrd@z Thu Jan 1 00:00:00 1970 From: James Chapman Subject: Re: [PATCH net-next 2/2] l2tp: add peer_offset parameter Date: Tue, 2 Jan 2018 20:59:44 +0000 Message-ID: References: <20171228145340.GA1292@alphalink.fr> <20171228182347.GA8732@localhost.localdomain> <20171228194556.GA1256@alphalink.fr> <27e0a7c8-b95b-04eb-d808-bcae67e417b1@katalix.com> <20180102180557.GB1402@alphalink.fr> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 8bit Cc: netdev@vger.kernel.org, Hangbin Liu To: Guillaume Nault , Lorenzo Bianconi , "David S. Miller" Return-path: Received: from mail.katalix.com ([82.103.140.233]:34067 "EHLO mail.katalix.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750726AbeABU7s (ORCPT ); Tue, 2 Jan 2018 15:59:48 -0500 In-Reply-To: Content-Language: en-GB Sender: netdev-owner@vger.kernel.org List-ID: On 02/01/18 20:08, James Chapman wrote: > On 02/01/18 18:05, Guillaume Nault wrote: >>>> Lorenzo, is this being added to fix interoperability with another >>>> L2TPv3 >>>> implementation? If so, can you share more details? >>>> >>> Hi James, >>> >>> I introduced peer_offset parameter to fix a specific setup where >>> tunnel endpoints >>> running L2TPv3 would use different values for tx offset (since in >>> iproute2 there is no >>> restriction on it), not to fix a given an interoperability issue. >>> >> Yes, but was it just to test iproute2's peer_offset option? Or is there >> a plan to use it for real? >> >>> I introduced this feature since: >>>   - offset has been added for long time to L2TPv3 implementation >>>     (commit f7faffa3ff8ef6ae712ef16312b8a2aa7a1c95fe and >>>     commit 309795f4bec2d69cd507a631f82065c2198a0825) and I wanted to >>> preserve UABI >>>   - have the same degree of freedom for offset parameter we have in >>> L2TPv2 and fix the issue >>>     described above >>> >> AFAIU, the current L2TPv2 implementation never sets the offset field >> and nobody ever realised. >> >>> Now what we can do I guess is: >>> - as suggested by Guillaume drop completely the offset support >>> without removing >>>    netlink attribute in order to not break UABI >>> - fix offset support initializing properly padding bits >>> >> I'd go for the first one. I just wonder if that looks acceptable to >> David an James. > > I think the first one too. Also update iproute2 to remove or hide the > offset and peer_offset parameters. > > I just realised the peer_offset attribute changes are already applied in net-next. (I missed these when they were submitted just before Christmas.) Should these commits be reverted? We probably don't want v4.15 to get an additional l2tp peer_offset attribute if we are going to remove it and the rest of the code supporting configurable offset attributes in the next release. 81487bf Merge branch 'l2tp-next' f15bc54 l2tp: add peer_offset parameter 820da53 l2tp: fix missing print session offset info