From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754540AbcEDWGJ (ORCPT ); Wed, 4 May 2016 18:06:09 -0400 Received: from cloud.av8n.com ([174.136.99.130]:51444 "EHLO cloud.av8n.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754364AbcEDWGG (ORCPT ); Wed, 4 May 2016 18:06:06 -0400 Subject: Re: linux/bitops.h To: "H. Peter Anvin" , tytso@mit.edu, noloader@gmail.com, linux-kernel@vger.kernel.org, Stephan Mueller , Herbert Xu , andi@firstfloor.org, Sandy Harris , cryptography@lakedaemon.net, linux-crypto@vger.kernel.org References: <1462170413-7164-1-git-send-email-tytso@mit.edu> <1462170413-7164-2-git-send-email-tytso@mit.edu> <20160504174901.GC3901@thunk.org> <20160504190723.GD3901@thunk.org> <572A6CDD.10503@av8n.com> From: John Denker Message-ID: <572A724C.6010704@av8n.com> Date: Wed, 4 May 2016 15:06:04 -0700 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.7.2 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Quilt: IylxH9ie7xzdJOnCpEMv5FubjyetnYLIwURAlvKHfWlEpTn8E0fjpWaLJYykSoGJ Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 05/04/2016 02:56 PM, H. Peter Anvin wrote: >> Beware that shifting by an amount >= the number of bits in the >> word remains Undefined Behavior. > This construct has been supported as a rotate since at least gcc2. How then should we understand the story told in commit d7e35dfa? Is the story wrong? At the very least, something inconsistent is going on. There are 8 functions. Why did d7e35dfa change one of them but not the other 7?