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=-2.1 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, 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 E18F9C2D0F1 for ; Mon, 30 Mar 2020 23:35:51 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id B226620774 for ; Mon, 30 Mar 2020 23:35:51 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="p87pYBLC" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729381AbgC3Xft (ORCPT ); Mon, 30 Mar 2020 19:35:49 -0400 Received: from mail-pg1-f196.google.com ([209.85.215.196]:33979 "EHLO mail-pg1-f196.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729196AbgC3Xft (ORCPT ); Mon, 30 Mar 2020 19:35:49 -0400 Received: by mail-pg1-f196.google.com with SMTP id l14so2322941pgb.1; Mon, 30 Mar 2020 16:35:46 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=subject:to:cc:references:from:message-id:date:user-agent :mime-version:in-reply-to:content-language:content-transfer-encoding; bh=Ihsd+LIKK09BkgBU5lK2nHCqw9TRvnbaMLRrOxk0h2k=; b=p87pYBLC3MmWCxVZxPixFPk6zecH/3RVA/V+yOI0oeJczOLk1ARxjJOILz3yRWLgh9 dpo1UMPXP/oOHEay3q8cjdIUnznd/37ul1yDXPofgGVctfE8neuhZsP+WzjN+aCDj9iS OOVobG4/HmQYZ3jG3i5O2CY7/cD7iiCetln5QPTQzyZNe6LCaSzMOGp8oNBwoOJZmZUi 1mk4RYiUQmiklpe5P+EkU8LTxHdr3j9OES2HMhberyOXNwUdxAD09N+2uIXtlAuopr+a 6rXTfjJ5hdjpi+0PTRpBFFl3mlzNJdwLw97inGC1pSO6SmPHu9yfL7IyaaPp/OebOubK whxg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:subject:to:cc:references:from:message-id:date :user-agent:mime-version:in-reply-to:content-language :content-transfer-encoding; bh=Ihsd+LIKK09BkgBU5lK2nHCqw9TRvnbaMLRrOxk0h2k=; b=Av06UhtnAYjYYBnrdqKiUk/3VzsD9LCzAsEjr7cVLnPEaBJ+J2CEFOFHpc/WCIR6DR phOSLtsLG0z+1lVg4tnUAMbD0gf/U1/hEgK5R0G6pUo9w5izOkdVCT0mqeyZcJ7EnF8B Wx6yebGY0ymV8Cp5tsMyfdJUU1Cp3+STgMt65KZ3idLNuQbyGzQBC9YjbuIlJOS5WCGg 4PAc0puzhFsp3Pg4l+dSx+K9BN1DB1i21cOIIOuZtnheFJEPVAX//o+P0J9rM88A6Ibj RzPtpwME/C555NcYLW2V/hHjmqe5xQPNkaJFPM58Oogep9QNfWQo1s9UuNILsf4r23iL Sh8A== X-Gm-Message-State: ANhLgQ3vHlN1xIpbK/DBcEz+KaBp/RioVsp3mPzgsro636/qSjWxTNHo Y6J0HEVX0OuZX2A1sW+9UPfdrKqG X-Google-Smtp-Source: ADFU+vu3oMl5981LfcveEQsB0jz8wUh2Fvws/6FzXOCgNF7QgTXM4QbqbUJrfuD3cK8bW+/d58RzFw== X-Received: by 2002:a63:1003:: with SMTP id f3mr15181161pgl.450.1585611345613; Mon, 30 Mar 2020 16:35:45 -0700 (PDT) Received: from [192.168.1.18] (i223-218-245-204.s42.a013.ap.plala.or.jp. [223.218.245.204]) by smtp.googlemail.com with ESMTPSA id gi2sm521816pjb.30.2020.03.30.16.35.41 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 30 Mar 2020 16:35:44 -0700 (PDT) Subject: Re: [PATCH net] veth: xdp: use head instead of hard_start To: Jesper Dangaard Brouer , Mao Wenan Cc: davem@davemloft.net, ast@kernel.org, daniel@iogearbox.net, kuba@kernel.org, hawk@kernel.org, john.fastabend@gmail.com, kafai@fb.com, songliubraving@fb.com, yhs@fb.com, andriin@fb.com, jwi@linux.ibm.com, jianglidong3@jd.com, edumazet@google.com, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, bpf@vger.kernel.org, kernel-janitors@vger.kernel.org References: <20200330102631.31286-1-maowenan@huawei.com> <20200330133442.132bde0c@carbon> From: Toshiaki Makita Message-ID: <3053de4c-cee6-f6fc-efc2-09c6250f3ef2@gmail.com> Date: Tue, 31 Mar 2020 08:35:39 +0900 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:68.0) Gecko/20100101 Thunderbird/68.6.0 MIME-Version: 1.0 In-Reply-To: <20200330133442.132bde0c@carbon> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org Hi Mao & Jesper (Resending with plain text...) On 2020/03/30 20:34, Jesper Dangaard Brouer wrote: > On Mon, 30 Mar 2020 18:26:31 +0800 > Mao Wenan wrote: > >> xdp.data_hard_start is mapped to the first >> address of xdp_frame, but the pointer hard_start >> is the offset(sizeof(struct xdp_frame)) of xdp_frame, >> it should use head instead of hard_start to >> set xdp.data_hard_start. Otherwise, if BPF program >> calls helper_function such as bpf_xdp_adjust_head, it >> will be confused for xdp_frame_end. > > I have noticed this[1] and have a patch in my current patchset for > fixing this. IMHO is is not so important fix right now, as the effect > is that you currently only lose 32 bytes of headroom. > > [1] https://lore.kernel.org/netdev/158446621887.702578.17234304084556809684.stgit@firesoul/ You are right, the subtraction is not necessary here. Thank you for working on this. Toshiaki Makita