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=-15.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS autolearn=ham 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 27712C2B9F4 for ; Fri, 25 Jun 2021 11:00:01 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 05C9B6145F for ; Fri, 25 Jun 2021 11:00:01 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229940AbhFYLCU (ORCPT ); Fri, 25 Jun 2021 07:02:20 -0400 Received: from relay.sw.ru ([185.231.240.75]:51496 "EHLO relay.sw.ru" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229445AbhFYLCT (ORCPT ); Fri, 25 Jun 2021 07:02:19 -0400 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=virtuozzo.com; s=relay; h=Content-Type:Mime-Version:Message-Id:Subject:From :Date; bh=Y8Tmva5LSabemDAgTdVRUCEIMwXrcd8byL8UmD6LHt8=; b=jEsSz18eBqmDJtmOi/0 A7QYi8L+sEcbp+CyBTX1AKSlBKH+l06jZcL5iXtQ1dag1AyIBEtgdSAQgqwIHAsTZTDIloaYsWdVu gOaPxI4ncz2CYWmVwcNoeerLQvZgJ7Y5VqM6vh4OLTWlHSRZ5zmYs9rjPnEq5EVe4o0qI8jsV7A=; Received: from [192.168.15.9] (helo=mikhalitsyn-laptop) by relay.sw.ru with esmtps (TLS1.3) tls TLS_AES_256_GCM_SHA384 (Exim 4.94.2) (envelope-from ) id 1lWQcG-001nm6-AH; Fri, 25 Jun 2021 13:59:57 +0300 Date: Fri, 25 Jun 2021 13:59:54 +0300 From: Alexander Mikhalitsyn To: Stephen Hemminger Cc: netdev@vger.kernel.org, David Ahern , Andrei Vagin , Alexander Mikhalitsyn Subject: Re: [PATCHv2 iproute2] ip route: ignore ENOENT during save if RT_TABLE_MAIN is being dumped Message-Id: <20210625135954.44ecba2e8875141380a52d7d@virtuozzo.com> In-Reply-To: <20210624083647.0f173c4b@hermes.local> References: <20210622150330.28014-1-alexander.mikhalitsyn@virtuozzo.com> <20210624152812.29031-1-alexander.mikhalitsyn@virtuozzo.com> <20210624083647.0f173c4b@hermes.local> X-Mailer: Sylpheed 3.7.0 (GTK+ 2.24.33; x86_64-redhat-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org On Thu, 24 Jun 2021 08:36:47 -0700 Stephen Hemminger wrote: > On Thu, 24 Jun 2021 18:28:12 +0300 > Alexander Mikhalitsyn wrote: > > > We started to use in-kernel filtering feature which allows to get only needed > > tables (see iproute_dump_filter()). From the kernel side it's implemented in > > net/ipv4/fib_frontend.c (inet_dump_fib), net/ipv6/ip6_fib.c (inet6_dump_fib). > > The problem here is that behaviour of "ip route save" was changed after > > c7e6371bc ("ip route: Add protocol, table id and device to dump request"). > > If filters are used, then kernel returns ENOENT error if requested table is absent, > > but in newly created net namespace even RT_TABLE_MAIN table doesn't exist. > > It is really allocated, for instance, after issuing "ip l set lo up". > > > > Reproducer is fairly simple: > > $ unshare -n ip route save > dump > > Error: ipv4: FIB table does not exist. > > Dump terminated > > > > Expected result here is to get empty dump file (as it was before this change). > > > > v2: reworked, so, now it takes into account NLMSGERR_ATTR_MSG > > (see nl_dump_ext_ack_done() function). We want to suppress error messages > > in stderr about absent FIB table from kernel too. > > > > Fixes: c7e6371bc ("ip route: Add protocol, table id and device to dump request") > > Cc: David Ahern > > Cc: Stephen Hemminger > > Cc: Andrei Vagin > > Cc: Alexander Mikhalitsyn > > Signed-off-by: Alexander Mikhalitsyn > > --- > > include/libnetlink.h | 5 +++++ > > ip/iproute.c | 8 +++++++- > > lib/libnetlink.c | 31 ++++++++++++++++++++++++++----- > > 3 files changed, 38 insertions(+), 6 deletions(-) > > > > diff --git a/include/libnetlink.h b/include/libnetlink.h > > index b9073a6a..93c22a09 100644 > > --- a/include/libnetlink.h > > +++ b/include/libnetlink.h > > @@ -121,6 +121,11 @@ int rtnl_dump_filter_nc(struct rtnl_handle *rth, > > void *arg, __u16 nc_flags); > > #define rtnl_dump_filter(rth, filter, arg) \ > > rtnl_dump_filter_nc(rth, filter, arg, 0) > > +int rtnl_dump_filter_suppress_rtnl_errmsg_nc(struct rtnl_handle *rth, > > + rtnl_filter_t filter, > > + void *arg1, __u16 nc_flags, const int *errnos); > > +#define rtnl_dump_filter_suppress_rtnl_errmsg(rth, filter, arg, errnos) \ > > + rtnl_dump_filter_suppress_rtnl_errmsg_nc(rth, filter, arg, 0, errnos) > > int rtnl_talk(struct rtnl_handle *rtnl, struct nlmsghdr *n, > > struct nlmsghdr **answer) > > __attribute__((warn_unused_result)); > > diff --git a/ip/iproute.c b/ip/iproute.c > > index 5853f026..796d6d17 100644 > > --- a/ip/iproute.c > > +++ b/ip/iproute.c > > @@ -1734,6 +1734,8 @@ static int iproute_list_flush_or_save(int argc, char **argv, int action) > > char *od = NULL; > > unsigned int mark = 0; > > rtnl_filter_t filter_fn; > > + /* last 0 is array trailing */ > > + int suppress_rtnl_errnos[2] = { 0, 0 }; > > > > The design would be clearer if there were two arguments rather than magic array of size 2. > Also these are being used as boolean. I've reworked that to make code cleaner and sent v3. I decided to keep array on the stack but introduced initializer-macro SUPPRESS_ERRORS_INIT which can be extended anytime (now it allows to suppress up to 3 errors). In iplink_vrf.c rtnl_talk_suppress_rtnl_errmsg function is used, which allows to suppress all errors, but sometime it may be helpful to suppress just a few errors. That's a reason why I didn't implemented variant which allows to suppress only one errno (ENOENT) for my particular case. Thanks, Alex