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=-6.9 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS autolearn=unavailable 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 BE48EC1975A for ; Tue, 17 Mar 2020 17:30:26 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 9322C20735 for ; Tue, 17 Mar 2020 17:30:26 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="Skadqx1j" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726858AbgCQRaZ (ORCPT ); Tue, 17 Mar 2020 13:30:25 -0400 Received: from us-smtp-delivery-74.mimecast.com ([63.128.21.74]:35692 "EHLO us-smtp-delivery-74.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726747AbgCQRaZ (ORCPT ); Tue, 17 Mar 2020 13:30:25 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1584466224; 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: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=yx3RZws4yQG7gnfYNWis4eEV1lTKG+jOjgsTDqL0uy4=; b=Skadqx1jc+2X9yuon2bT0VmTNvyYo5G+gX/b+C7fSsHcKzovl7MgUvaKjhGhEf/s2cIS0I QqOeL1aSX2vTu5U0KgDX3bDG7FJ4QwzeJoi4kU+1nZgBYNylY56UakgnfWmgGrXmE5jCr5 eppR6Tt+Gzm8VR3d+wsFw4nROhEfAo0= 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-440-XnU9gnxyNTaB9hxOwPbNGQ-1; Tue, 17 Mar 2020 13:30:10 -0400 X-MC-Unique: XnU9gnxyNTaB9hxOwPbNGQ-1 Received: from smtp.corp.redhat.com (int-mx03.intmail.prod.int.phx2.redhat.com [10.5.11.13]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id E5C50802C86; Tue, 17 Mar 2020 17:29:59 +0000 (UTC) Received: from firesoul.localdomain (unknown [10.40.208.26]) by smtp.corp.redhat.com (Postfix) with ESMTP id 81B4860BEE; Tue, 17 Mar 2020 17:29:59 +0000 (UTC) Received: from [192.168.42.3] (localhost [IPv6:::1]) by firesoul.localdomain (Postfix) with ESMTP id 9288930721A66; Tue, 17 Mar 2020 18:29:58 +0100 (CET) Subject: [PATCH RFC v1 10/15] net: XDP-generic determining XDP frame size From: Jesper Dangaard Brouer To: sameehj@amazon.com Cc: Jesper Dangaard Brouer , netdev@vger.kernel.org, bpf@vger.kernel.org, zorik@amazon.com, akiyano@amazon.com, gtzalik@amazon.com, =?utf-8?q?Toke_H=C3=B8iland-J=C3=B8rgensen?= , Daniel Borkmann , Alexei Starovoitov , John Fastabend , Alexander Duyck , Jeff Kirsher , David Ahern , Willem de Bruijn , Ilias Apalodimas , Lorenzo Bianconi Date: Tue, 17 Mar 2020 18:29:58 +0100 Message-ID: <158446619851.702578.5555301782398712923.stgit@firesoul> In-Reply-To: <158446612466.702578.2795159620575737080.stgit@firesoul> References: <158446612466.702578.2795159620575737080.stgit@firesoul> User-Agent: StGit/0.19 MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit X-Scanned-By: MIMEDefang 2.79 on 10.5.11.13 Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org The SKB "head" pointer points to the data area that contains skb_shared_info, that can be found via skb_end_pointer(). Given xdp->data_hard_start have been established (basically pointing to skb->head), frame size is between skb_end_pointer() and data_hard_start, plus the size reserved to skb_shared_info. Change the bpf_xdp_adjust_tail fix up of skb->len, to be a positive offset number on grow, and negative number on shrink. As this seems more natural when reading the code Signed-off-by: Jesper Dangaard Brouer --- net/core/dev.c | 14 ++++++++------ 1 file changed, 8 insertions(+), 6 deletions(-) diff --git a/net/core/dev.c b/net/core/dev.c index 9c941cd38b13..645e5c48a52f 100644 --- a/net/core/dev.c +++ b/net/core/dev.c @@ -4546,6 +4546,11 @@ static u32 netif_receive_generic_xdp(struct sk_buff *skb, xdp->data_meta = xdp->data; xdp->data_end = xdp->data + hlen; xdp->data_hard_start = skb->data - skb_headroom(skb); + + /* SKB "head" area always have tailroom for skb_shared_info */ + xdp->frame_sz = (void *)skb_end_pointer(skb) - xdp->data_hard_start; + xdp->frame_sz += SKB_DATA_ALIGN(sizeof(struct skb_shared_info)); + orig_data_end = xdp->data_end; orig_data = xdp->data; eth = (struct ethhdr *)xdp->data; @@ -4569,14 +4574,11 @@ static u32 netif_receive_generic_xdp(struct sk_buff *skb, skb_reset_network_header(skb); } - /* check if bpf_xdp_adjust_tail was used. it can only "shrink" - * pckt. - */ - off = orig_data_end - xdp->data_end; + /* check if bpf_xdp_adjust_tail was used */ + off = xdp->data_end - orig_data_end; if (off != 0) { skb_set_tail_pointer(skb, xdp->data_end - xdp->data); - skb->len -= off; - + skb->len += off; /* positive on grow, negative on shrink */ } /* check if XDP changed eth hdr such SKB needs update */