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=-7.2 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS 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 C5225C4338F for ; Sat, 24 Jul 2021 08:13:12 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 9325E60E97 for ; Sat, 24 Jul 2021 08:13:12 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234555AbhGXHcU (ORCPT ); Sat, 24 Jul 2021 03:32:20 -0400 Received: from us-smtp-delivery-124.mimecast.com ([216.205.24.124]:38629 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234232AbhGXHcT (ORCPT ); Sat, 24 Jul 2021 03:32:19 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1627114370; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=93hq5CZItUG7Rw8nFRa2iRJVTYVV2mYt138MAmHu6C4=; b=iRbd+TzSvtH/7lUksqgONe/4yMRpr4vnHn5mmJmZRCXlzinblgxzQw2BGzrnLcvkaeBMjO LxTMgDvoalOE5qrgFUXVl3SyMteRrH+nZb+7KVT2/2IAj6yaW0xwypxqfXA88zN2t9avUb 0xKpFkTcR4jeF8wsAbsfvDvg7sOiW1c= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-457-bCY0bk2oM6GxySqTQGq4jQ-1; Sat, 24 Jul 2021 04:12:48 -0400 X-MC-Unique: bCY0bk2oM6GxySqTQGq4jQ-1 Received: from smtp.corp.redhat.com (int-mx02.intmail.prod.int.phx2.redhat.com [10.5.11.12]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 3E69E801A92; Sat, 24 Jul 2021 08:12:47 +0000 (UTC) Received: from Laptop-X1 (ovpn-13-95.pek2.redhat.com [10.72.13.95]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 0FD6960C0F; Sat, 24 Jul 2021 08:12:43 +0000 (UTC) Date: Sat, 24 Jul 2021 16:12:39 +0800 From: Hangbin Liu To: Andrii Nakryiko Cc: Martynas Pumputis , Networking , Stephen Hemminger , David Ahern , Daniel Borkmann Subject: Re: [PATCH iproute2] libbpf: fix attach of prog with multiple sections Message-ID: References: <20210705124307.201303-1-m@lambda.lt> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Scanned-By: MIMEDefang 2.79 on 10.5.11.12 Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org On Fri, Jul 23, 2021 at 09:09:01AM -0700, Andrii Nakryiko wrote: > On Fri, Jul 23, 2021 at 12:55 AM Hangbin Liu wrote: > > > > On Thu, Jul 22, 2021 at 09:51:50PM -0700, Andrii Nakryiko wrote: > > > > > > This is still problematic, because one section can have multiple BPF > > > > > > programs. I.e., it's possible two define two or more XDP BPF programs > > > > > > all with SEC("xdp") and libbpf works just fine with that. I suggest > > > > > > moving users to specify the program name (i.e., C function name > > > > > > representing the BPF program). All the xdp_mycustom_suffix namings are > > > > I just propose an implementation as you suggested. > > > > > > > > a hack and will be rejected by libbpf 1.0, so it would be great to get > > > > > > a head start on fixing this early on. > > > > > > > > > > Thanks for bringing this up. Currently, there is no way to specify a > > > > > function name with "tc exec bpf" (only a section name via the "sec" arg). So > > > > > probably, we should just add another arg to specify the function name. > > > > > > > > How about add a "prog" arg to load specified program name and mark > > > > "sec" as not recommended? To keep backwards compatibility we just load the > > > > first program in the section. > > > > > > Why not error out if there is more than one program with the same > > > section name? if there is just one (and thus section name is still > > > unique) -- then proceed. It seems much less confusing, IMO. > > > > If you and others think it's OK to only support one program each section. > > I do no object. > > > > I'm not sure we are on the same page. I'll try to summarize what I > understood and you guys can decide for yourself what you want to do. > > So I like your idea of introducing "prog" arg that will expect BPF > program name (i.e., C function name). In that case the name is always > unique. For existing "sec" arg, for backwards compatibility, I'd keep > it working, but when "sec" is used I'd check that the match is unique > (i.e., there is only one BPF program within the specified section). If > not and there are more than one matching BPF programs, that's a hard > error, because otherwise you essentially randomly pick one BPF program > out of a few. Cool, we are in the same page now. Thanks Hangbin