Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753521Ab3JFPNy (ORCPT ); Sun, 6 Oct 2013 11:13:54 -0400 Received: from order.stressinduktion.org ([87.106.68.36]:43862 "EHLO order.stressinduktion.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752712Ab3JFPNx (ORCPT ); Sun, 6 Oct 2013 11:13:53 -0400 Date: Sun, 6 Oct 2013 17:13:51 +0200 From: Hannes Frederic Sowa To: Oussama Ghorbel Cc: "David S. Miller" , Alexey Kuznetsov , James Morris , Hideaki YOSHIFUJI , Patrick McHardy , netdev@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] Fix the upper MTU limit in ipv6 GRE tunnel Message-ID: <20131006151351.GB9295@order.stressinduktion.org> Mail-Followup-To: Oussama Ghorbel , "David S. Miller" , Alexey Kuznetsov , James Morris , Hideaki YOSHIFUJI , Patrick McHardy , netdev@vger.kernel.org, linux-kernel@vger.kernel.org References: <1380880333-3546-1-git-send-email-ou.ghorbel@gmail.com> <20131005140636.GA25076@order.stressinduktion.org> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1449 Lines: 46 On Sun, Oct 06, 2013 at 03:42:15PM +0100, Oussama Ghorbel wrote: > The initialization in ip6gre_tnl_link_config is done as the following: > static void ip6gre_tnl_link_config(struct ip6_tnl *t, int set_mtu) > { > ... > int addend = sizeof(struct ipv6hdr) + 4; > ... > /* Precalculate GRE options length */ > if (t->parms.o_flags&(GRE_CSUM|GRE_KEY|GRE_SEQ)) { > if (t->parms.o_flags&GRE_CSUM) > addend += 4; > if (t->parms.o_flags&GRE_KEY) > addend += 4; > if (t->parms.o_flags&GRE_SEQ) > addend += 4; > } > ... > dev->hard_header_len = rt->dst.dev->hard_header_len + addend; > ... > t->hlen = addend; > .. > } > > Unless they are other reasons, the hard_header_len is taken into > account the GRE_KEY, GRE_SEQ .. But only if a new route is found. The hard_header_len reinitialization is guarded by a (rt == NULL). We may have not found one on boot up. > > To make this correct we would have to refactor the usage of the variables a > > bit as is done in ipv4/ip_tunnel.c. The safest thing would be to leave this > > check as-is currently although we exclude some allowed mtus. > > > > Perhaps you want to take a look how to achieve that? ;) > > > Why not, consistency is good ... Thanks, Hannes -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/