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=-5.3 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,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 DB173C43331 for ; Mon, 11 Nov 2019 18:01:44 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id AE591206BA for ; Mon, 11 Nov 2019 18:01:44 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726927AbfKKSBo (ORCPT ); Mon, 11 Nov 2019 13:01:44 -0500 Received: from dispatch1-us1.ppe-hosted.com ([67.231.154.164]:38292 "EHLO dispatch1-us1.ppe-hosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726910AbfKKSBo (ORCPT ); Mon, 11 Nov 2019 13:01:44 -0500 X-Virus-Scanned: Proofpoint Essentials engine Received: from webmail.solarflare.com (uk.solarflare.com [193.34.186.16]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-SHA384 (256/256 bits)) (No client certificate requested) by mx1-us5.ppe-hosted.com (PPE Hosted ESMTP Server) with ESMTPS id 79175580051; Mon, 11 Nov 2019 18:01:41 +0000 (UTC) Received: from [10.17.20.203] (10.17.20.203) by ukex01.SolarFlarecom.com (10.17.10.4) with Microsoft SMTP Server (TLS) id 15.0.1395.4; Mon, 11 Nov 2019 18:01:33 +0000 Subject: Re: [PATCH net-next] sfc: trace_xdp_exception on XDP failure To: Arthur Fabre CC: Solarflare linux maintainers , "Charles McLachlan" , Martin Habets , David Miller , "Alexei Starovoitov" , Daniel Borkmann , "Jakub Kicinski" , Jesper Dangaard Brouer , John Fastabend , netdev , bpf , kernel-team References: <20191111105100.2992-1-afabre@cloudflare.com> From: Edward Cree Message-ID: <6a3705cc-809d-0c7a-d39f-97d61c4ce58c@solarflare.com> Date: Mon, 11 Nov 2019 18:01:30 +0000 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.7.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset="utf-8" Content-Language: en-US Content-Transfer-Encoding: 7bit X-Originating-IP: [10.17.20.203] X-ClientProxiedBy: ocex03.SolarFlarecom.com (10.20.40.36) To ukex01.SolarFlarecom.com (10.17.10.4) X-TM-AS-Product-Ver: SMEX-12.5.0.1300-8.5.1010-25036.003 X-TM-AS-Result: No-6.224200-8.000000-10 X-TMASE-MatchedRID: QW5G6BKkLTrmLzc6AOD8DfHkpkyUphL9SeIjeghh/zNcpms3pMhT0ciT Wug2C4DNl1M7KT9/aqDCGaYSzXQ4OcxAixoJws1YA9lly13c/gHYuVu0X/rOkPa7agslQWYYS8X QUmo7QNjtxcbrBYMsBPI1z1fnOPlxeW+Dbewdu5u84C/3iwAgxBfbPFE2GHrVX30pMm+iz0jD1l mWT+88Nu0ooccEm+Y0l57hPGdoWxvti3IwtSm+K5qvoi7RQmPSBnIRIVcCWN9Z+M9E/Hx6KHs6g pw5sMWK4vM1YF6AJbZFi+KwZZttL7ew1twePJJB3QfwsVk0UbsIoUKaF27lxbFqR/fS2lRWQI+Z YiTJvTP3JJ+Vk6CDGYP9zRn7y7SSAPJbQtdK6V5drZQZg8ilGyo0N27D4SnfxH+VL6lfYyS5tBV HNvTD6aKAQfLsnhLrKWSt4DmvbhpicKLmK2TeKmsPn5C6nWpTnqg/VrSZEiM= X-TM-AS-User-Approved-Sender: Yes X-TM-AS-User-Blocked-Sender: No X-TMASE-Result: 10--6.224200-8.000000 X-TMASE-Version: SMEX-12.5.0.1300-8.5.1010-25036.003 X-MDID: 1573495303-L0Xg_U-n0USA Sender: bpf-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: bpf@vger.kernel.org On 11/11/2019 17:38, Arthur Fabre wrote: > On Mon, Nov 11, 2019 at 5:27 PM Edward Cree wrote: >> >> On 11/11/2019 10:51, Arthur Fabre wrote: >>> diff --git a/drivers/net/ethernet/sfc/rx.c b/drivers/net/ethernet/sfc/rx.c >>> index a7d9841105d8..5bfe1f6112a1 100644 >>> --- a/drivers/net/ethernet/sfc/rx.c >>> +++ b/drivers/net/ethernet/sfc/rx.c >>> @@ -678,6 +678,7 @@ static bool efx_do_xdp(struct efx_nic *efx, struct efx_channel *channel, >>> "XDP is not possible with multiple receive fragments (%d)\n", >>> channel->rx_pkt_n_frags); >>> channel->n_rx_xdp_bad_drops++; >>> + trace_xdp_exception(efx->net_dev, xdp_prog, xdp_act); >>> return false; >>> } >> AIUI trace_xdp_exception() is improper here as we have not run >> the XDP program (and xdp_act is thus uninitialised). >> >> The other three, below, appear to be correct. >> -Ed >> > > Good point. Do you know under what conditions we'd end up with > "fragmented" packets? As far as I can tell this isn't IP > fragmentation? Fragments in this case means that the packet data are spread across multiple RX buffers (~= memory pages). This should only happen if the RX packet is too big to fit in a single buffer, and when enabling XDP we ensure that the MTU is small enough to prevent that. So in theory this can't happen if the NIC is functioning correctly. -Ed