From mboxrd@z Thu Jan 1 00:00:00 1970 From: Peter Oskolkov Subject: Re: [PATCH net] net/ipv6: do not copy DST_NOCOUNT flag on rt init Date: Mon, 17 Sep 2018 09:11:35 -0700 Message-ID: References: <20180913203814.189698-1-posk@google.com> <351e6fbc-5356-b5c1-0638-0554843ad833@gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Cc: davem@davemloft.net, netdev@vger.kernel.org To: dsahern@gmail.com Return-path: Received: from mail-lj1-f193.google.com ([209.85.208.193]:36608 "EHLO mail-lj1-f193.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726795AbeIQVjq (ORCPT ); Mon, 17 Sep 2018 17:39:46 -0400 Received: by mail-lj1-f193.google.com with SMTP id v26-v6so13711945ljj.3 for ; Mon, 17 Sep 2018 09:11:44 -0700 (PDT) In-Reply-To: <351e6fbc-5356-b5c1-0638-0554843ad833@gmail.com> Sender: netdev-owner@vger.kernel.org List-ID: On Thu, Sep 13, 2018 at 9:11 PM David Ahern wrote: > > On 9/13/18 1:38 PM, Peter Oskolkov wrote: > > > diff --git a/net/ipv6/route.c b/net/ipv6/route.c > > index 3eed045c65a5..a3902f805305 100644 > > --- a/net/ipv6/route.c > > +++ b/net/ipv6/route.c > > @@ -946,7 +946,7 @@ static void ip6_rt_init_dst_reject(struct rt6_info *rt, struct fib6_info *ort) > > > > static void ip6_rt_init_dst(struct rt6_info *rt, struct fib6_info *ort) > > { > > - rt->dst.flags |= fib6_info_dst_flags(ort); > > + rt->dst.flags |= fib6_info_dst_flags(ort) & ~DST_NOCOUNT; > > I think my mistake is setting dst.flags in ip6_rt_init_dst. Flags > argument is passed to ip6_dst_alloc which is always invoked before > ip6_rt_copy_init is called which is the only caller of ip6_rt_init_dst. ip6_rt_cache_alloc calls ip6_dst_alloc with zero as flags; and only one flag is copied later (DST_HOST) outside of ip6_rt_init_dst(). If the flag assignment is completely removed from ip6_rt_init_dst(), then DST_NOPOLICY flag will be lost. Which may be OK, but is more than what this patch tries to solve (do not copy DST_NOCOUNT flag). > > > > > if (ort->fib6_flags & RTF_REJECT) { > > ip6_rt_init_dst_reject(rt, ort); > > >