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=-1.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS,URIBL_BLOCKED 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 C0C0AC282C3 for ; Thu, 24 Jan 2019 11:56:43 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 942B921872 for ; Thu, 24 Jan 2019 11:56:43 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727535AbfAXL4m (ORCPT ); Thu, 24 Jan 2019 06:56:42 -0500 Received: from www62.your-server.de ([213.133.104.62]:53080 "EHLO www62.your-server.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726105AbfAXL4m (ORCPT ); Thu, 24 Jan 2019 06:56:42 -0500 Received: from [78.46.172.3] (helo=sslproxy06.your-server.de) by www62.your-server.de with esmtpsa (TLSv1.2:DHE-RSA-AES256-GCM-SHA384:256) (Exim 4.89_1) (envelope-from ) id 1gmdcb-0004VO-H1; Thu, 24 Jan 2019 12:56:37 +0100 Received: from [178.197.249.22] (helo=linux.home) by sslproxy06.your-server.de with esmtpsa (TLSv1.2:ECDHE-RSA-AES256-GCM-SHA384:256) (Exim 4.89) (envelope-from ) id 1gmdcb-000C8K-B0; Thu, 24 Jan 2019 12:56:37 +0100 Subject: Re: [PATCH bpf-next v2 2/8] libbpf: Add a helper for retrieving a prog via index To: Jesper Dangaard Brouer , Maciej Fijalkowski Cc: ast@kernel.org, netdev@vger.kernel.org, jakub.kicinski@netronome.com References: <20190121091041.14666-1-maciejromanfijalkowski@gmail.com> <20190121091041.14666-3-maciejromanfijalkowski@gmail.com> <91d162e0-3d15-c1d8-1e80-8d0a4f561540@iogearbox.net> <20190123144159.000051bd@gmail.com> <20190123152451.7fcdb226@redhat.com> From: Daniel Borkmann Message-ID: <99b1958f-d04c-2b4a-81c1-e9942512df37@iogearbox.net> Date: Thu, 24 Jan 2019 12:56:36 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.3.0 MIME-Version: 1.0 In-Reply-To: <20190123152451.7fcdb226@redhat.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit X-Authenticated-Sender: daniel@iogearbox.net X-Virus-Scanned: Clear (ClamAV 0.100.2/25326/Thu Jan 24 03:30:43 2019) Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org On 01/23/2019 03:24 PM, Jesper Dangaard Brouer wrote: > On Wed, 23 Jan 2019 14:41:59 +0100 > Maciej Fijalkowski wrote: > >> On Wed, 23 Jan 2019 11:41:11 +0100 >> Daniel Borkmann wrote: >> >>> On 01/21/2019 10:10 AM, Maciej Fijalkowski wrote: >>>> xdp_redirect_cpu has a 6 different XDP programs that can be attached to >>>> network interface. This sample has a option --prognum that allows user >>>> for specifying which particular program from a given set will be >>>> attached to network interface. >>>> In order to make it easier when converting the mentioned sample to >>>> libbpf usage, add a function to libbpf that will return program's fd for >>>> a given index. >>>> >>>> Note that there is already a bpf_object__find_prog_by_idx, which could >>>> be exported and might be used for that purpose, but it operates on the >>>> number of ELF section and here we need an index from a programs array >>>> within the bpf_object. >>> >>> Series in general looks good to me. Few minor comments, mainly in relation >>> to the need for libbpf extensions. >>> >>> Would it not be a better interface to the user to instead choose the prog >>> based on section name and then retrieve it via bpf_object__find_program_by_title() >>> instead of prognum (which feels less user friendly) at least? >> >> I couldn't decide which one from: >> * adding a libbpf helper >> * changing the xdp_redirect_cpu behaviour >> >> would be more invasive when I was converting this sample to libbpf >> support. >> >> Your suggestion sounds good, but I'm wondering about the actual >> implementation. I suppose that we would choose the program via >> command line. Some program section names in this sample are a bit >> long and it might be irritating for user to type in for example >> "xdp_cpu_map5_lb_hash_ip_pairs", no? Or maybe we can live with this. >> In case of typo and program being not found it would be good to print >> out the section names to choose from in usage(). > > Please feel free to deprecate or remove the xdp_redirect_cpu --prognum > option. I would prefer if this was indeed converted to selecting the > program based on the name in the _kern.c file, instead of a number. Given this is BPF sample code, there is no need to deprecate, lets just remove --prognum option and add a new one for selection by name. > Listing the avail programs will be helpful, and you can also > shorten/rename the program names. > > For easy of use, consider doing like 'ip' tool from[1] iproute2, and > find the first best matching string. Copy pasted code below signature > for inspiration.