Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S945835AbcJaTPj (ORCPT ); Mon, 31 Oct 2016 15:15:39 -0400 Received: from shards.monkeyblade.net ([184.105.139.130]:56290 "EHLO shards.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S945816AbcJaTPg (ORCPT ); Mon, 31 Oct 2016 15:15:36 -0400 Date: Mon, 31 Oct 2016 15:15:34 -0400 (EDT) Message-Id: <20161031.151534.329043104568805244.davem@davemloft.net> To: jkbs@redhat.com Cc: tom@herbertland.com, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, kuznet@ms2.inr.ac.ru, jmorris@namei.org, yoshfuji@linux-ipv6.org, kaber@trash.net Subject: Re: [PATCH net-next 5/5] ipv6: Compute multipath hash for forwarded ICMP errors from offending packet From: David Miller In-Reply-To: <8760oa9egg.fsf@redhat.com> References: <8760oa9egg.fsf@redhat.com> X-Mailer: Mew version 6.7 on Emacs 24.5 / Mule 6.0 (HANACHIRUSATO) Mime-Version: 1.0 Content-Type: Text/Plain; charset=us-ascii Content-Transfer-Encoding: 7bit X-Greylist: Sender succeeded SMTP AUTH, not delayed by milter-greylist-4.5.12 (shards.monkeyblade.net [149.20.54.216]); Mon, 31 Oct 2016 11:16:01 -0700 (PDT) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 813 Lines: 22 From: Jakub Sitnicki Date: Sun, 30 Oct 2016 14:03:11 +0100 > 2) ensure the flow labels used in both directions are the same (either > reflected by one side, or fixed, e.g. not used and set to 0), so that > the 4-tuple we hash over when forwarding, label, next hdr>, is the same both ways, modulo the order of > addresses. Even Linux, by default, does not do reflection. See the flowlabel_consistency sysctl, which we set by default to '1'. I think we need to think a lot more about how systems actually set and use flowlabels. Also, one issue I also had with this series was adding a new member to the flow label. Is it possible to implement this like the ipv4 side did, by simply passing a new parameter around to the necessary functions? Thanks.