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=-11.2 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 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 09992C41604 for ; Sat, 3 Oct 2020 11:17:49 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id BE40F206C9 for ; Sat, 3 Oct 2020 11:17:48 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1725768AbgJCLRs (ORCPT ); Sat, 3 Oct 2020 07:17:48 -0400 Received: from correo.us.es ([193.147.175.20]:37478 "EHLO mail.us.es" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725730AbgJCLRs (ORCPT ); Sat, 3 Oct 2020 07:17:48 -0400 Received: from antivirus1-rhel7.int (unknown [192.168.2.11]) by mail.us.es (Postfix) with ESMTP id F32BC120831 for ; Sat, 3 Oct 2020 13:17:45 +0200 (CEST) Received: from antivirus1-rhel7.int (localhost [127.0.0.1]) by antivirus1-rhel7.int (Postfix) with ESMTP id E3BB7DA791 for ; Sat, 3 Oct 2020 13:17:45 +0200 (CEST) Received: by antivirus1-rhel7.int (Postfix, from userid 99) id D97F6DA789; Sat, 3 Oct 2020 13:17:45 +0200 (CEST) Received: from antivirus1-rhel7.int (localhost [127.0.0.1]) by antivirus1-rhel7.int (Postfix) with ESMTP id 98F40DA704; Sat, 3 Oct 2020 13:17:43 +0200 (CEST) Received: from 192.168.1.97 (192.168.1.97) by antivirus1-rhel7.int (F-Secure/fsigk_smtp/550/antivirus1-rhel7.int); Sat, 03 Oct 2020 13:17:43 +0200 (CEST) X-Virus-Status: clean(F-Secure/fsigk_smtp/550/antivirus1-rhel7.int) Received: from us.es (unknown [90.174.3.162]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) (Authenticated sender: 1984lsi) by entrada.int (Postfix) with ESMTPSA id 30EA642EF9E0; Sat, 3 Oct 2020 13:17:43 +0200 (CEST) Date: Sat, 3 Oct 2020 13:17:41 +0200 X-SMTPAUTHUS: auth mail.us.es From: Pablo Neira Ayuso To: Phil Sutter Cc: netfilter-devel@vger.kernel.org, Serhey Popovych Subject: Re: [iptables PATCH 1/3] libxtables: Make sure extensions register in revision order Message-ID: <20201003111741.GA3035@salvia> References: <20200922225341.8976-1-phil@nwl.cc> <20200922225341.8976-2-phil@nwl.cc> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20200922225341.8976-2-phil@nwl.cc> User-Agent: Mutt/1.10.1 (2018-07-13) X-Virus-Scanned: ClamAV using ClamSMTP Precedence: bulk List-ID: X-Mailing-List: netfilter-devel@vger.kernel.org Hi Phil, On Wed, Sep 23, 2020 at 12:53:39AM +0200, Phil Sutter wrote: > Insert extensions into pending lists in ordered fashion: Group by > extension name (and, for matches, family) and order groups by descending > revision number. > > This allows to simplify the later full registration considerably. Since > that involves kernel compatibility checks, the extra cycles here pay off > eventually. > > Signed-off-by: Phil Sutter > --- > libxtables/xtables.c | 64 +++++++++++++++++++++++++++++++++++++++----- > 1 file changed, 58 insertions(+), 6 deletions(-) > > diff --git a/libxtables/xtables.c b/libxtables/xtables.c > index 8907ba2069be7..63d0ea5def2d5 100644 > --- a/libxtables/xtables.c > +++ b/libxtables/xtables.c > @@ -948,8 +948,14 @@ static void xtables_check_options(const char *name, const struct option *opt) > } > } > > +static int xtables_match_prefer(const struct xtables_match *a, > + const struct xtables_match *b); > + > void xtables_register_match(struct xtables_match *me) > { > + struct xtables_match **pos; > + bool seen_myself = false; > + > if (me->next) { > fprintf(stderr, "%s: match \"%s\" already registered\n", > xt_params->program_name, me->name); > @@ -1001,10 +1007,32 @@ void xtables_register_match(struct xtables_match *me) > if (me->extra_opts != NULL) > xtables_check_options(me->name, me->extra_opts); > > + /* order into linked list of matches pending full registration */ > + for (pos = &xtables_pending_matches; *pos; pos = &(*pos)->next) { > + /* NOTE: No extension_cmp() here as we accept all families */ > + if (strcmp(me->name, (*pos)->name) || > + me->family != (*pos)->family) { > + if (seen_myself) > + break; > + continue; > + } > + seen_myself = true; > + if (xtables_match_prefer(me, *pos) >= 0) xtables_match_prefer() evaluates >= 0 if 'me' has higher revision number than *pos. So list order is: higher revision first. > + break; > + } > + if (!*pos) > + pos = &xtables_pending_matches; > > - /* place on linked list of matches pending full registration */ > - me->next = xtables_pending_matches; > - xtables_pending_matches = me; > + me->next = *pos; This line above is placing 'me' right before the existing match in the list. > + *pos = me; This line above only works if *pos is &xtables_pending_matches? Looking at the in-tree extensions, they are always ordered from lower to higher (in array definitions).