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=-6.0 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS 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 60157C433E0 for ; Mon, 29 Mar 2021 15:01:05 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 28DF661964 for ; Mon, 29 Mar 2021 15:01:05 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230338AbhC2PAd (ORCPT ); Mon, 29 Mar 2021 11:00:33 -0400 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]:35701 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229441AbhC2PAT (ORCPT ); Mon, 29 Mar 2021 11:00:19 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1617030018; 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=EESeojbqeVR2ASo5IFJfG55+A5xo+WiBGyPWEwtfTjg=; b=aQJrVY/pmnJ6VESc9eibgXVV/g2HPOWQts5hS2kYEGoSLQJMANGQ/JPznT4tmEuLkajM1j GBf7u/Clv4VW/ABfSeD+9HMlRexkRRQaDRm3VVuGqzFQOgHNUTTfUDJCNDzD+NNKNxPU4T QWgkRvDrw8+NuC+fnsbv0zUMActS08A= 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-224-EUzCiIqKNOOzPxdGbMNTjg-1; Mon, 29 Mar 2021 11:00:15 -0400 X-MC-Unique: EUzCiIqKNOOzPxdGbMNTjg-1 Received: from smtp.corp.redhat.com (int-mx07.intmail.prod.int.phx2.redhat.com [10.5.11.22]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 8DCEE18C8C06; Mon, 29 Mar 2021 15:00:13 +0000 (UTC) Received: from ovpn-114-151.ams2.redhat.com (ovpn-114-151.ams2.redhat.com [10.36.114.151]) by smtp.corp.redhat.com (Postfix) with ESMTP id 2D01710027A5; Mon, 29 Mar 2021 15:00:10 +0000 (UTC) Message-ID: Subject: Re: [PATCH net-next v2 1/8] udp: fixup csum for GSO receive slow path From: Paolo Abeni To: Willem de Bruijn Cc: Network Development , "David S. Miller" , Jakub Kicinski , Steffen Klassert , Alexander Lobakin Date: Mon, 29 Mar 2021 17:00:09 +0200 In-Reply-To: References: <28d04433c648ea8143c199459bfe60650b1a0d28.1616692794.git.pabeni@redhat.com> <1a33dd110b4b43a7d65ce55e13bff4a69b89996c.camel@redhat.com> Content-Type: text/plain; charset="UTF-8" User-Agent: Evolution 3.36.5 (3.36.5-2.fc32) MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Scanned-By: MIMEDefang 2.84 on 10.5.11.22 Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org On Mon, 2021-03-29 at 09:52 -0400, Willem de Bruijn wrote: > > > That breaks the checksum-and-copy optimization when delivering to > > > local sockets. I wonder if that is a regression. > > > > The conversion to CHECKSUM_UNNECESSARY happens since > > commit 573e8fca255a27e3573b51f9b183d62641c47a3d. > > > > Even the conversion to CHECKSUM_PARTIAL happens independently from this > > series, since commit 6f1c0ea133a6e4a193a7b285efe209664caeea43. > > > > I don't see a regression here ?!? > > I mean that UDP packets with local destination socket and no tunnels > that arrive with CHECKSUM_NONE normally benefit from the > checksum-and-copy optimization in recvmsg() when copying to user. > > If those packets are now checksummed during GRO, that voids that > optimization, and the packet payload is now touched twice. The 'now' part confuses me. Nothing in this patch or this series changes the processing of CHECKSUM_NONE UDP packets with no tunnel. I do see checksum validation in the GRO engine for CHECKSUM_NONE UDP packet prior to this series. I *think* the checksum-and-copy optimization is lost since 573e8fca255a27e3573b51f9b183d62641c47a3d. Regards, Paolo