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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id EAD55C4167B for ; Wed, 6 Dec 2023 22:44:10 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1377646AbjLFWoC (ORCPT ); Wed, 6 Dec 2023 17:44:02 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:48648 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229642AbjLFWoB (ORCPT ); Wed, 6 Dec 2023 17:44:01 -0500 Received: from zeniv.linux.org.uk (zeniv.linux.org.uk [IPv6:2a03:a000:7:0:5054:ff:fe1c:15ff]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 24D8ED5B; Wed, 6 Dec 2023 14:44:07 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=linux.org.uk; s=zeniv-20220401; h=Sender:In-Reply-To:Content-Type: MIME-Version:References:Message-ID:Subject:Cc:To:From:Date:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=To9ucKTvN543g4EQHIcIczpJa6wUxMMz7xk5pdznqwo=; b=d7JS3LFBmBt2LemFl6aJnf7yrF pktEdrm6H+yEfe9JcinFzn2+knQltLAeCaA+mlRWiBCntnBj1n6YexrKopAcaIm7/wBwzlptDJfjg lQcKyE45QDLdcJHeY50G+k/QkMfNYiuJV9uB51Jf3EF8ZecSwBh3AKgKZGINkhCSOT6v3fRcgbNVV dRD9F667VjY15hhfGY2eXLoh3nusDt3R1U4sP9tTYX9qCv9rkVunAt0zmmuQCOcR12J/t0/Rijk5G 5QsQX7NfkvItf5GJoUy8sNbDLuEMTli4wF3kZ/zaknTxGzIlvCyWsggLgXndvhWj+AtfXb2VR7xqj atGi9E0g==; Received: from viro by zeniv.linux.org.uk with local (Exim 4.96 #2 (Red Hat Linux)) id 1rB0ca-007y6e-06; Wed, 06 Dec 2023 22:44:00 +0000 Date: Wed, 6 Dec 2023 22:43:59 +0000 From: Al Viro To: David Laight Cc: "linux-arch@vger.kernel.org" , gus Gusenleitner Klaus , Al Viro , Thomas Gleixner , lkml , Ingo Molnar , "bp@alien8.de" , "dave.hansen@linux.intel.com" , "x86@kernel.org" , "David S. Miller" , "dsahern@kernel.org" , "kuba@kernel.org" , Paolo Abeni , Eric Dumazet Subject: Re: [RFC][PATCHES v2] checksum stuff Message-ID: <20231206224359.GR1674809@ZenIV> References: <20231019050250.GV800259@ZenIV> <20231019061427.GW800259@ZenIV> <20231019063925.GX800259@ZenIV> <20231019080615.GY800259@ZenIV> <20231021071525.GA789610@ZenIV> <20231021222203.GA800259@ZenIV> <20231022194020.GA972254@ZenIV> <20231205022100.GB1674809@ZenIV> <602ab11ffa2c4cc49bb9ecae2f0540b0@AcuMS.aculab.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <602ab11ffa2c4cc49bb9ecae2f0540b0@AcuMS.aculab.com> Sender: Al Viro Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Dec 06, 2023 at 11:10:45AM +0000, David Laight wrote: > Do we? > I've not seen any justification for this at all. > IIRC the ICMPv4 reply code needs the checksum function return 0xffff > for all-zero input. > > So the correct and simple fix is to initialise the sum to 0xffff > in the checksum function. You do realize that ICMPv4 reply code is not the only user of those, right? Sure, we can special-case it there. And audit the entire call tree, proving that no other call chains need the same. Care to post the analysis? I have the beginnings of that and it's already long and convoluted and touches far too many places, all of which will have to be watched indefinitely, so that changes in there don't introduce new breakage. I could be wrong. About many things, including the depth of your aversion to RTFS. But frankly, until that analysis shows up somewhere, I'm going to ignore your usual handwaving.