From mboxrd@z Thu Jan 1 00:00:00 1970 From: Eric Dumazet Subject: Re: [PATCH net] ipv6: kill sk_dst_lock Date: Mon, 30 Nov 2015 10:27:32 -0800 Message-ID: <1448908052.24696.136.camel@edumazet-glaptop2.roam.corp.google.com> References: <1448730683.24696.94.camel@edumazet-glaptop2.roam.corp.google.com> <1448731434.24696.97.camel@edumazet-glaptop2.roam.corp.google.com> <1448854142.24696.109.camel@edumazet-glaptop2.roam.corp.google.com> <1448901315.24696.127.camel@edumazet-glaptop2.roam.corp.google.com> <1448907188.5804.31.camel@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit Cc: Dmitry Vyukov , "David S. Miller" , Vlad Yasevich , Hideaki YOSHIFUJI , netdev To: Paolo Abeni Return-path: Received: from mail-pa0-f41.google.com ([209.85.220.41]:34699 "EHLO mail-pa0-f41.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753899AbbK3S1e (ORCPT ); Mon, 30 Nov 2015 13:27:34 -0500 Received: by padhx2 with SMTP id hx2so192399640pad.1 for ; Mon, 30 Nov 2015 10:27:33 -0800 (PST) In-Reply-To: <1448907188.5804.31.camel@redhat.com> Sender: netdev-owner@vger.kernel.org List-ID: On Mon, 2015-11-30 at 19:13 +0100, Paolo Abeni wrote: > On Mon, 2015-11-30 at 08:35 -0800, Eric Dumazet wrote: > > ip6_sk_dst_lookup_flow() uses sk_dst_check() anyway, so the simplest > > way to fix the mess is to remove sk_dst_lock completely, as we did for > > IPv4. > > Probably I'm missing something here, but why we don't need to sync the > update of sk_dst_cache and of dst_cookie (i.e. put them under the same > lock)? > > Can't we end up with inconsistent values after concurrent udp > sendmsg() ? I do not think this is an issue. A route is best effort. If really a packet is dropped during a route flap, no big deal, especially if this is during a fuzzer test ;)