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=-2.6 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_PASS,USER_AGENT_NEOMUTT 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 921CDECDFB3 for ; Mon, 16 Jul 2018 22:30:10 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 43190208E8 for ; Mon, 16 Jul 2018 22:30:10 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="Z+NEjSGB" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 43190208E8 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=gmail.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729859AbeGPW7f (ORCPT ); Mon, 16 Jul 2018 18:59:35 -0400 Received: from mail-pg1-f196.google.com ([209.85.215.196]:42734 "EHLO mail-pg1-f196.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728947AbeGPW7f (ORCPT ); Mon, 16 Jul 2018 18:59:35 -0400 Received: by mail-pg1-f196.google.com with SMTP id y4-v6so8011601pgp.9; Mon, 16 Jul 2018 15:30:07 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to:user-agent; bh=3LCBQukFGsv7pauFjoa3wVWBHgP7axdu3xwNudgBOKw=; b=Z+NEjSGBXUghub3usZwsJskptsjZeNoepsfK7jCP6L9FKRlUwvY/MQuDl9sfoNCPO0 K84KziD/VfJ3waoho0oymSp2WVDyU8eAkim5m++DqacqIr0qjPIgdpeZBcOoP3dGoBtA lyO/BresJWEtm+NKR6Xt3jeLeBmAbg+KWvYAcDJLkGum83BslkALJ3QmtDA3lf0kDc6X U54HPAtkXkOR/bZrMKEpOhgR7B1IBdXudVnClOBpkSBhauLoGjxgqUTVH8vb37j7skMD Ort9UALUkxDGGCal3YZkaODsBjvviUg3NU4fWl6F3KOEQxIUg8F1y0aogQCvB6UDkgfL YUfQ== 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=3LCBQukFGsv7pauFjoa3wVWBHgP7axdu3xwNudgBOKw=; b=o8r48yS9TRn4G/6Yk3ocGN2SOWJ9NvFz6gMISQd/5AO2iRf1sLKiF6Z86YDw/Fnjxq iaXTEUrPI3vkhqm69PCWotvIT50nXOJI8GFKYbSATG7Asnzp+a5YiH230HW13AW9I0QB dHwERuJDfiCX6cXKoDCb6dNrzsZ6BuGURuWYfNzMjl0sRs0iPUYe6cW1tHZiddUUDXIM prxj0tjrVlYXl+GaFawiPMx+kRMxR7WA9NCXhG7eA6VU+hT4/LwZ2wUSksUcHcp3wKc0 oSOkNuIecGqdPUagjym08mwQ3hPTefL7clzV+4AFz4eirlI057ZDMn5slhS5q/XiIOoi i76g== X-Gm-Message-State: AOUpUlEv642D4DuvyQ554ZLziDU7uIX4TK1PLMZNwXmu7/F4jvNXToPk HFlUGiX9tmLcizkkvggZmRiAl9Xa X-Google-Smtp-Source: AAOMgpfLn3lmfSAGkQkHjVY08jpEnnxE6Qm/2d+H2QxK5hfPiRajo4V3IVenQv+/Dyg9kpJFVSi4kg== X-Received: by 2002:a62:5dd7:: with SMTP id n84-v6mr19914575pfj.68.1531780207300; Mon, 16 Jul 2018 15:30:07 -0700 (PDT) Received: from ast-mbp.dhcp.thefacebook.com ([2620:10d:c090:200::7:3f88]) by smtp.gmail.com with ESMTPSA id a25-v6sm45161458pgv.51.2018.07.16.15.30.05 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Mon, 16 Jul 2018 15:30:06 -0700 (PDT) Date: Mon, 16 Jul 2018 15:30:04 -0700 From: Alexei Starovoitov To: Eddie Hao Cc: ast@kernel.org, daniel@iogearbox.net, davem@davemloft.net, netdev@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] bpf: allow BPF programs access skb_shared_info->gso_segs field Message-ID: <20180716223003.fvh6edj3zlfegy52@ast-mbp.dhcp.thefacebook.com> References: <20180715084524.181717-1-eddieh@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20180715084524.181717-1-eddieh@google.com> User-Agent: NeoMutt/20180223 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sun, Jul 15, 2018 at 01:45:24AM -0700, Eddie Hao wrote: > This adds the ability to read gso_segs from a BPF program. This is useful > for user space monitoring systems to get gso_segs statistics for each > arbitrary group of flows defined by the BPF program. > > Signed-off-by: Eddie Hao > --- > include/uapi/linux/bpf.h | 1 + > net/core/filter.c | 9 +++++++++ > 2 files changed, 10 insertions(+) > > diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h > index b7db3261c62d..282085445616 100644 > --- a/include/uapi/linux/bpf.h > +++ b/include/uapi/linux/bpf.h > @@ -2266,6 +2266,7 @@ struct __sk_buff { > /* ... here. */ > > __u32 data_meta; > + unsigned short gso_segs; 'short' will make it harder to extend due to struct hole. please use __u32 instead. > }; > > struct bpf_tunnel_key { > diff --git a/net/core/filter.c b/net/core/filter.c > index b9ec916f4e3a..f17e249f3fbb 100644 > --- a/net/core/filter.c > +++ b/net/core/filter.c > @@ -5820,6 +5820,15 @@ static u32 bpf_convert_ctx_access(enum bpf_access_type type, > bpf_target_off(struct sock_common, > skc_num, 2, target_size)); > break; > + > + case offsetof(struct __sk_buff, gso_segs): > + BUILD_BUG_ON(FIELD_SIZEOF(struct skb_shared_info, gso_segs) != > + sizeof(unsigned short)); > + off = offsetof(struct sk_buff, end); > + off += offsetof(struct skb_shared_info, gso_segs); did you test this patch? Above math doesn't look correct. NET_SKBUFF_DATA_USES_OFFSET is not handled. At least one more LDX is needed. > + *insn++ = BPF_LDX_MEM(BPF_SIZEOF(unsigned short), si->dst_reg, > + si->src_reg, off); I think BUILD_BUG_ON is a bit of overkill when BPF_LDX_MEM can use BPF_FIELD_SIZEOF(struct skb_shared_info, gso_segs) instead.