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=-3.8 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS,URIBL_BLOCKED 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 D8A06C43461 for ; Wed, 2 Sep 2020 12:47:40 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id A93BC207D3 for ; Wed, 2 Sep 2020 12:47:40 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="B7mS5Yxd" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726984AbgIBMrj (ORCPT ); Wed, 2 Sep 2020 08:47:39 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:53060 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726762AbgIBMrh (ORCPT ); Wed, 2 Sep 2020 08:47:37 -0400 Received: from merlin.infradead.org (merlin.infradead.org [IPv6:2001:8b0:10b:1231::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 87D75C061244; Wed, 2 Sep 2020 05:47:35 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=merlin.20170209; h=In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=R5emDCN9N+tW0SHI20K3hMIZd+UDNfkLh7iRsInsea8=; b=B7mS5Yxdq0lOp/JdxuBG2tf0d5 c/h+WDVvE7ES/O7GnGA8tH4moh+pjEdRhSrwSzMxz4ufJKcMC0CfwcaK3mEH1TMqYtnjvJKuuFLXY 8yBXXwZfaXkugcfom75sM2ogbzidgzxx1i9gAPt1peE33bhXpp2amdmUlCFfbT2Rh46nyNuZctJBj /W69r8SQ2N/M2a7VedMWmqVeMLupoWzcm0MxyS2kXb7zPS7BLFE1FZ0gEwE23nf5miRRSdT60Vqlv QGsKbcqUP1oArmBTq43iLXi+rK6aPBJvFtLO5NQlm3CoQKx/r7Xukhzyb4xpaltHN5kvmOaT7gZRr XpX6oIAQ==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=noisy.programming.kicks-ass.net) by merlin.infradead.org with esmtpsa (Exim 4.92.3 #3 (Red Hat Linux)) id 1kDSAh-0003qC-3I; Wed, 02 Sep 2020 12:47:27 +0000 Received: from hirez.programming.kicks-ass.net (hirez.programming.kicks-ass.net [192.168.1.225]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (Client did not present a certificate) by noisy.programming.kicks-ass.net (Postfix) with ESMTPS id 893843011C6; Wed, 2 Sep 2020 14:47:25 +0200 (CEST) Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id 7979F23D3D72C; Wed, 2 Sep 2020 14:47:25 +0200 (CEST) Date: Wed, 2 Sep 2020 14:47:25 +0200 From: peterz@infradead.org To: Boqun Feng Cc: paulmck@kernel.org, linux-kernel@vger.kernel.org, linux-arch@vger.kernel.org, kernel-team@fb.com, mingo@kernel.org, stern@rowland.harvard.edu, parri.andrea@gmail.com, will@kernel.org, npiggin@gmail.com, dhowells@redhat.com, j.alglave@ucl.ac.uk, luc.maranget@inria.fr, akiyks@gmail.com Subject: Re: [PATCH kcsan 6/9] tools/memory-model: Expand the cheatsheet.txt notion of relaxed Message-ID: <20200902124725.GF1362448@hirez.programming.kicks-ass.net> References: <20200831182012.GA1965@paulmck-ThinkPad-P72> <20200831182037.2034-6-paulmck@kernel.org> <20200902035448.GC49492@debian-boqun.qqnc3lrjykvubdpftowmye0fmh.lx.internal.cloudapp.net> <20200902101412.GC1362448@hirez.programming.kicks-ass.net> <20200902123715.GD49492@debian-boqun.qqnc3lrjykvubdpftowmye0fmh.lx.internal.cloudapp.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200902123715.GD49492@debian-boqun.qqnc3lrjykvubdpftowmye0fmh.lx.internal.cloudapp.net> Sender: linux-arch-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-arch@vger.kernel.org On Wed, Sep 02, 2020 at 08:37:15PM +0800, Boqun Feng wrote: > On Wed, Sep 02, 2020 at 12:14:12PM +0200, peterz@infradead.org wrote: > > > To be accurate, atomic_set() doesn't return any value, so it cannot be > > > ordered against DR and DW ;-) > > > > Surely DW is valid for any store. > > > > IIUC, the DW colomn stands for whether the corresponding operation (in > this case, it's atomic_set()) is ordered any write that depends on this > operation. I don't think there is a write->write dependency, so DW for > atomic_set() should not be Y, just as the DW for WRITE_ONCE(). Ah, just shows I can't read I suppose ;-) I thought we were talking of the other side of the depency.