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=-0.8 required=3.0 tests=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 E70C3C5DF60 for ; Fri, 8 Nov 2019 19:57:34 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id C61402067B for ; Fri, 8 Nov 2019 19:57:34 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2388926AbfKHT5d convert rfc822-to-8bit (ORCPT ); Fri, 8 Nov 2019 14:57:33 -0500 Received: from mout.kundenserver.de ([212.227.126.131]:50579 "EHLO mout.kundenserver.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2388678AbfKHT5d (ORCPT ); Fri, 8 Nov 2019 14:57:33 -0500 Received: from mail-qk1-f169.google.com ([209.85.222.169]) by mrelayeu.kundenserver.de (mreue009 [212.227.15.129]) with ESMTPSA (Nemesis) id 1N7zJj-1hpgym2s8x-0151yp; Fri, 08 Nov 2019 20:57:31 +0100 Received: by mail-qk1-f169.google.com with SMTP id h15so6339492qka.13; Fri, 08 Nov 2019 11:57:31 -0800 (PST) X-Gm-Message-State: APjAAAVmtIn+xsVYCTCzLtPfK6bfCyoI+heb1Ny+7/sidNHAzVRIbLNu wTxoflQFzvlPZWpjJmCEEOr+4R8zUcG6EZByXok= X-Google-Smtp-Source: APXvYqwbEOv9N5n3ZVSMCaT2AayZZFizNM7xZNN/vq5TItdY6JMB/hXbfpzfEILBcvqaJNvSbipOgEpXoOH0B2jqyjk= X-Received: by 2002:a37:4f13:: with SMTP id d19mr10475357qkb.138.1573243050314; Fri, 08 Nov 2019 11:57:30 -0800 (PST) MIME-Version: 1.0 References: <20191108170120.22331-1-will@kernel.org> <20191108170120.22331-2-will@kernel.org> In-Reply-To: <20191108170120.22331-2-will@kernel.org> From: Arnd Bergmann Date: Fri, 8 Nov 2019 20:57:14 +0100 X-Gmail-Original-Message-ID: Message-ID: Subject: Re: [PATCH 01/13] compiler.h: Split {READ,WRITE}_ONCE definitions out into rwonce.h To: Will Deacon Cc: "linux-kernel@vger.kernel.org" , Yunjae Lee , SeongJae Park , "Paul E. McKenney" , Josh Triplett , Matt Turner , Ivan Kokshaysky , Richard Henderson , Peter Zijlstra , Alan Stern , Michael Ellerman , "Michael S. Tsirkin" , Jason Wang , Joe Perches , Boqun Feng , alpha , virtualization@lists.linux-foundation.org, Christian Borntraeger Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 8BIT X-Provags-ID: V03:K1:WN2iI+qyF2aSt8E8GeKGmxpYo3P2QxddmHwDuUf+2xOBmvCiXN1 kfo03Y5w0Ed4/W8YtsfC67k8nnzv9O2z9711Ijn03wGaGTixokJJiaw8tAHBJ9cYCbCssiz Y2PsFV9C1+nQzCzb82xfQ06UlKQRgwLbbTKvxd2E7K8Gy5O38Glw7sMriEYvgOHRMSuO3q1 GaxO+KieHHsxR9s9J7o2Q== X-UI-Out-Filterresults: notjunk:1;V03:K0:bYkMvnYhV+E=:5i3VTKBS0g9a2FZ+pwIr/h YGXwH9EYPtpdpROfWmYRD8/qsvV5WJtT9N4XydZgBoxBTkEKg4CUMYzn/GpaQjz5kMOXfnF1f MppuGBcAI5xDJpx7/bOD4Cjt2zvLYJIaCzH8cU5MHM01uUndyxLEcA5KoAzUzexHN34ly4Di6 3K9cuWzfla586x0lmwdxYkBLCbwApbKUc29p5d4sx2jS28pTqqGYovQdriPQ2INaUIjitX68x yHQYLiEv4gTceKnDvGfN85XlUEH2xH9/2l2uHpaHXPp7raydECobeYgohHlLS+g59JjHzdFQX Bc3ah8+euWPyRK+Etayp9cnuiqm/UmdNIcPdoKbsDEugcMW9BAQ2qDSurObGnIH15EnnZvfEF 4LheLtq4DWgU72V2Rr2vPTZco1DXkJ4w7kAcxDs3Ts36ZJpjjaTxzoUvrmkWFKu3o1NsSSdtz 6diG03KThrYLE4Aza5PiV3jt6QL1NvcR6M9nARqhQFzOG6ObZm9QZI0TrTvADlKe1LFVJ3s6m RGkpxNSrGt/7D/zBz3UDeBXB3tANmBEZnLr5smBbJE7mKI12z0vVNmX6rU4Bva5fg2YdqGNWN k48lfUG2+PJqzcbKozpHvqN52rswG2476rp2jPCIlPr0KZY8MT3DwUm4zkIUnzivZRPRtGaUS 5YWKXSsJ09jptgYVHmIMccRcFrauU+PmsavJHTP1hXeXeRUrrM56JrFtOlm5G5ZsEKxftZrnh 6aYlRvZkotFNPVdZ+jZRQ4V+hPXC+AWwMExucHXDN+2dQl0g0TJvKPOqJwnvu/oLxHjf6cGDz MGDr1slo0ciqEUpnP5XOlbKcNg127ZJTOUv1v9gMGYx8HUrai2US24TbwHYvbYPFl9siebGd4 pM58UcjGFKWFvwd3Z9Dg== Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Nov 8, 2019 at 6:01 PM Will Deacon wrote: > > In preparation for allowing architectures to define their own > implementation of the 'READ_ONCE()' macro, move the generic > '{READ,WRITE}_ONCE()' definitions out of the unwieldy 'linux/compiler.h' > and into a new 'rwonce.h' header under 'asm-generic'. Adding Christian Bornträger to Cc, he originally added the READ_ONCE()/WRITE_ONCE() code. I wonder if it would be appropriate now to revert back to a much simpler version of these helpers for any modern compiler. As I understand, only gcc-4.6 and gcc4.7 actually need the song-and-dance version with the union and switch/case, while for others, we can might be able back to a macro doing a volatile access. Arnd