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=-2.3 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=no 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 D81E1C83000 for ; Wed, 29 Apr 2020 21:12:39 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id BD9EC206F0 for ; Wed, 29 Apr 2020 21:12:39 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726871AbgD2VMj (ORCPT ); Wed, 29 Apr 2020 17:12:39 -0400 Received: from correo.us.es ([193.147.175.20]:53284 "EHLO mail.us.es" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726511AbgD2VMj (ORCPT ); Wed, 29 Apr 2020 17:12:39 -0400 Received: from antivirus1-rhel7.int (unknown [192.168.2.11]) by mail.us.es (Postfix) with ESMTP id 788BF12BFE0 for ; Wed, 29 Apr 2020 23:12:37 +0200 (CEST) Received: from antivirus1-rhel7.int (localhost [127.0.0.1]) by antivirus1-rhel7.int (Postfix) with ESMTP id 68260BAAB4 for ; Wed, 29 Apr 2020 23:12:37 +0200 (CEST) Received: by antivirus1-rhel7.int (Postfix, from userid 99) id 5DA43BAAAF; Wed, 29 Apr 2020 23:12:37 +0200 (CEST) Received: from antivirus1-rhel7.int (localhost [127.0.0.1]) by antivirus1-rhel7.int (Postfix) with ESMTP id 6229F5211E for ; Wed, 29 Apr 2020 23:12:35 +0200 (CEST) Received: from 192.168.1.97 (192.168.1.97) by antivirus1-rhel7.int (F-Secure/fsigk_smtp/550/antivirus1-rhel7.int); Wed, 29 Apr 2020 23:12:35 +0200 (CEST) X-Virus-Status: clean(F-Secure/fsigk_smtp/550/antivirus1-rhel7.int) Received: from us.es (unknown [90.77.255.23]) (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 4553842EF9E0 for ; Wed, 29 Apr 2020 23:12:35 +0200 (CEST) Date: Wed, 29 Apr 2020 23:12:34 +0200 X-SMTPAUTHUS: auth mail.us.es From: Pablo Neira Ayuso To: Netfilter Development Subject: Re: [PATCH libnetfilter_queue 0/3] pktbuff API updates Message-ID: <20200429211234.GB14508@salvia> References: <20200426132356.8346-1-pablo@netfilter.org> <20200427110614.GA15436@dimstar.local.net> <20200427170656.GA22296@salvia> <20200428043302.GB15436@dimstar.local.net> <20200428103407.GA1160@salvia> <20200428211452.GF15436@dimstar.local.net> <20200428225520.GA30421@salvia> <20200429132840.GA3833@dimstar.local.net> <20200429190020.GA16096@salvia> <20200429195414.GC3833@dimstar.local.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200429195414.GC3833@dimstar.local.net> User-Agent: Mutt/1.10.1 (2018-07-13) X-Virus-Scanned: ClamAV using ClamSMTP Sender: netfilter-devel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netfilter-devel@vger.kernel.org On Thu, Apr 30, 2020 at 05:54:14AM +1000, Duncan Roe wrote: > On Wed, Apr 29, 2020 at 09:00:20PM +0200, Pablo Neira Ayuso wrote: > > On Wed, Apr 29, 2020 at 11:28:40PM +1000, Duncan Roe wrote: > > > On Wed, Apr 29, 2020 at 12:55:20AM +0200, Pablo Neira Ayuso wrote: > > > > On Wed, Apr 29, 2020 at 07:14:52AM +1000, Duncan Roe wrote: > > > > > On Tue, Apr 28, 2020 at 12:34:07PM +0200, Pablo Neira Ayuso wrote: > > > > [...] > > > I think we should not be usurping the data pointer of mnl_cb_run(). > > > I can see people wanting to use it to pass a pointer to e.g. some > > > kind of database that callbacks need to access. There's no > > > performance gain to recycling the buffer: the CB doesn't need to > > > call pktb_head_size() on every invocation, that can be done once by > > > main() e.g. > > > > > > static size_t sizeof_head; > > > ... > > > int main(int argc, char *argv[]) > > > { > > > ... > > > sizeof_head = pktb_head_size(); /* Avoid multiple calls in CB */ > > > ... > > > static int queue_cb(const struct nlmsghdr *nlh, void *data) > > > { > > > char head[sizeof_head]; > > > > You might also declare the pre-allocated pkt_buff as a global if you > > don't want to use the data pointer in mnl_cb_run(). > > I'm uneasy about this. We're writing a library here. We shouldn't be dictating > to the user that he must declare globals. "static" won't do in a multi-threaded > program, but you could use "thread local" (malloc'd under the covers, (tiny) > performance hit c/w stack (which is always thread local)). > > "The road to bloat is paved with tiny performance hits" [1] In nf_queue, the way to go is to set the _GSO flag on the client and then set on NFT_QUEUE_FLAG_CPU_FANOUT from the nft queue rule. If you need multiple processes, then users pre-allocate one pkt_buff per process.