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=-2.5 required=3.0 tests=DKIMWL_WL_MED,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_PASS, USER_AGENT_MUTT 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 240FEC282CB for ; Wed, 6 Feb 2019 00:59:36 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id E10792175B for ; Wed, 6 Feb 2019 00:59:35 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=fomichev-me.20150623.gappssmtp.com header.i=@fomichev-me.20150623.gappssmtp.com header.b="ICl72fB2" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728576AbfBFA7e (ORCPT ); Tue, 5 Feb 2019 19:59:34 -0500 Received: from mail-pg1-f196.google.com ([209.85.215.196]:44829 "EHLO mail-pg1-f196.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726062AbfBFA7e (ORCPT ); Tue, 5 Feb 2019 19:59:34 -0500 Received: by mail-pg1-f196.google.com with SMTP id y1so2167368pgk.11 for ; Tue, 05 Feb 2019 16:59:33 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=fomichev-me.20150623.gappssmtp.com; s=20150623; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to:user-agent; bh=MORWZMacA9oyM1vgFq+zQlKzZ0lAVkIoA7mubZUS49o=; b=ICl72fB29N4ESYSf5mha0eLHzRHpXfZq/ViYo8sLMqCrKfCZiD/qVXPHw9AT1htylL KUg9SVWec5erVIbA+GJHu97mHpTqZAfwutomB7vVhpU/BQqmy1jJb8vVYMK5IFlg6ghX UvPd5mnCjtLyxWpCQAXovOegFon6KJ18ZFvQ+YcMBY3u6EXgtJ7GU07iPiGKyV76yeQZ KKx4C8Yf7yorl+250PwTOV4OGc/O9cew8NHrL/LageiL6SVTPsIRX1miB/oUtbx/gVu4 A3a1o5jb+uzpPi5BN3DBc5WGQ8ZeSjAtlyvOSdwT8MKzmbdwpWe9pJRvnChT3Y6C+npj zGHA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to:user-agent; bh=MORWZMacA9oyM1vgFq+zQlKzZ0lAVkIoA7mubZUS49o=; b=ZTD++JWi5xasdjH/INr1EntV/70OqTUCfoJjI1rRTA1QVSN8ifu59+dFFgtGrxVjvU XapgdwHPa89/c3vE8ZHQvY8eut78i5xm937kiyDip4l8SP1mDs/usxHXFww8XmnWwGmD 2CkMlyXkI+G8bnA9chzf/KykpQc2jsTQOKVJsQPITjCOrBfwT4AdS2hAgYocxqvonqkb yKWgDfuBj1shsa+ZRkABcTv0HNBt3NfxdBks7w5F3SPA1VCZdvGJbO4EvAGTxaklfS6n OQFrrP4CKdQqoqPbgZPML06lUTcnXsyyE8TJPyrRtYs7WtstZs7x/8c5rR/doBK6X7hP eg0Q== X-Gm-Message-State: AHQUAuaYiPeg7yF7elC0D9/arSAITaGU58AWVyMFC5MPPXFz318nJiKk 9ZZgCfw1xsz3Xm2SX6htdVEFgg== X-Google-Smtp-Source: AHgI3IYfG1L5rYgAUokynm4Ey4gzgfb3y4aDta0d2A5DyWVMt330NjxBBEiP7241pf0ku1QrCVCEyQ== X-Received: by 2002:a62:3241:: with SMTP id y62mr7839408pfy.178.1549414772898; Tue, 05 Feb 2019 16:59:32 -0800 (PST) Received: from localhost ([2601:646:8f00:18d9:d0fa:7a4b:764f:de48]) by smtp.gmail.com with ESMTPSA id b5sm8230711pfc.150.2019.02.05.16.59.31 (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Tue, 05 Feb 2019 16:59:32 -0800 (PST) Date: Tue, 5 Feb 2019 16:59:31 -0800 From: Stanislav Fomichev To: Alexei Starovoitov Cc: Willem de Bruijn , Stanislav Fomichev , Network Development , David Miller , Alexei Starovoitov , Daniel Borkmann , simon.horman@netronome.com, Willem de Bruijn Subject: Re: [RFC bpf-next 0/7] net: flow_dissector: trigger BPF hook when called from eth_get_headlen Message-ID: <20190206005931.GF10769@mini-arch> References: <20190205173629.160717-1-sdf@google.com> <20190205204003.GB10769@mini-arch> <20190206004714.pz44evow5uwgvt4x@ast-mbp.dhcp.thefacebook.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190206004714.pz44evow5uwgvt4x@ast-mbp.dhcp.thefacebook.com> User-Agent: Mutt/1.11.2 (2019-01-07) Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org On 02/05, Alexei Starovoitov wrote: > On Tue, Feb 05, 2019 at 12:40:03PM -0800, Stanislav Fomichev wrote: > > On 02/05, Willem de Bruijn wrote: > > > On Tue, Feb 5, 2019 at 12:57 PM Stanislav Fomichev wrote: > > > > > > > > Currently, when eth_get_headlen calls flow dissector, it doesn't pass any > > > > skb. Because we use passed skb to lookup associated networking namespace > > > > to find whether we have a BPF program attached or not, we always use > > > > C-based flow dissector in this case. > > > > > > > > The goal of this patch series is to add new networking namespace argument > > > > to the eth_get_headlen and make BPF flow dissector programs be able to > > > > work in the skb-less case. > > > > > > > > The series goes like this: > > > > 1. introduce __init_skb and __init_skb_shinfo; those will be used to > > > > initialize temporary skb > > > > 2. introduce skb_net which can be used to get networking namespace > > > > associated with an skb > > > > 3. add new optional network namespace argument to __skb_flow_dissect and > > > > plumb through the callers > > > > 4. add new __flow_bpf_dissect which constructs temporary on-stack skb > > > > (using __init_skb) and calls BPF flow dissector program > > > > > > The main concern I see with this series is this cost of skb zeroing > > > for every packet in the device driver receive routine, *independent* > > > from the real skb allocation and zeroing which will likely happen > > > later. > > Yes, plus ~200 bytes on the stack for the callers. > > > > Not sure how visible this zeroing though, I can probably try to get some > > numbers from BPF_PROG_TEST_RUN (running current version vs running with > > on-stack skb). > > imo extra 256 byte memset for every packet is non starter. We can put pre-allocated/initialized skbs without data into percpu or even use pcpu_freelist_pop/pcpu_freelist_push to make sure we don't have to think about having multiple percpu for irq/softirq/process contexts. Any concerns with that approach? Any other possible concerns with the overall series?