From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-0.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 6C94BC432C0 for ; Tue, 3 Dec 2019 02:47:11 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 3F1C320684 for ; Tue, 3 Dec 2019 02:47:11 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726142AbfLCCrK (ORCPT ); Mon, 2 Dec 2019 21:47:10 -0500 Received: from shards.monkeyblade.net ([23.128.96.9]:44208 "EHLO shards.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725941AbfLCCrK (ORCPT ); Mon, 2 Dec 2019 21:47:10 -0500 Received: from localhost (unknown [IPv6:2601:601:9f00:1c3::3d5]) (using TLSv1 with cipher AES256-SHA (256/256 bits)) (Client did not present a certificate) (Authenticated sender: davem-davemloft) by shards.monkeyblade.net (Postfix) with ESMTPSA id 6364314F121E1; Mon, 2 Dec 2019 18:47:07 -0800 (PST) Date: Mon, 02 Dec 2019 18:47:04 -0800 (PST) Message-Id: <20191202.184704.723174427717421022.davem@davemloft.net> To: liuhangbin@gmail.com Cc: netdev@vger.kernel.org, ja@ssi.bg, marcelo.leitner@gmail.com, dsahern@gmail.com, edumazet@google.com Subject: Re: [PATCHv2 net] ipv6/route: should not update neigh confirm time during PMTU update From: David Miller In-Reply-To: <20191203021137.26809-1-liuhangbin@gmail.com> References: <20191122061919.26157-1-liuhangbin@gmail.com> <20191203021137.26809-1-liuhangbin@gmail.com> X-Mailer: Mew version 6.8 on Emacs 26.1 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, 02 Dec 2019 18:47:07 -0800 (PST) Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org From: Hangbin Liu Date: Tue, 3 Dec 2019 10:11:37 +0800 > Fix it by removing the dst_confirm_neigh() in __ip6_rt_update_pmtu() as > there is no two-way communication during PMTU update. > > v2: remove dst_confirm_neigh directly as David Miller pointed out. That's not what I said. I said that this interface is designed for situations where the neigh update is appropriate, and that's what happens for most callers _except_ these tunnel cases. The tunnel use is the exception and invoking the interface inappropriately. It is important to keep the neigh reachability fresh for TCP flows so you cannot remove this dst_confirm_neigh() call. Instead, make a new interface that the tunnel use cases can call into to elide the neigh update. Yes, this means you will have too update all of the tunnel callers into these calls chains but that's the price we have to pay in this situation unfortunately.