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=-2.1 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 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 52E06C2BA83 for ; Fri, 14 Feb 2020 08:12:44 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 2903F222C2 for ; Fri, 14 Feb 2020 08:12:44 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="tj2Myhm/" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729069AbgBNIMn (ORCPT ); Fri, 14 Feb 2020 03:12:43 -0500 Received: from mail-wm1-f67.google.com ([209.85.128.67]:34963 "EHLO mail-wm1-f67.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728332AbgBNIMX (ORCPT ); Fri, 14 Feb 2020 03:12:23 -0500 Received: by mail-wm1-f67.google.com with SMTP id b17so9581012wmb.0; Fri, 14 Feb 2020 00:12:21 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to:user-agent; bh=p+whp3SRlB3fcTDZeactPintXvEpOGniGrr5mWYhRNY=; b=tj2Myhm/kLBda1uCPkEcFyxgHOGUbf9nPC1yRk/wUGuz3xW2N2cp/BOztmVEpms2Iw Es2XmgXYlQlpR8cCq/qJGJqbaS2YJGjLERM0Wp8vKGgBVWV77Wkp0NuImZkCNd1y2cNc VDOYA9dGfR+XSLecDu2M4nV4E53S5K1IP49BAvuslw2NJftNUCs23UVi5KEvgJcbzniq cnI9gau1+0Zot2mJr4sMXgifFoqX/EmzWuJ6aR/HcS1jauqY1emNNQm0tXqcPkHtPNYQ 5+A8eAPKOW7NxdilnDZVvwb9Wruj8vFilFKX78eOCr0upl4xY6RURct1ehT493Q0jjV6 tRnQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to:user-agent; bh=p+whp3SRlB3fcTDZeactPintXvEpOGniGrr5mWYhRNY=; b=US8s8+Qw9MQ4Q3KYKfXED1XDpOr0Jq3lRm1+698XckKfyFLXknrhCiEbsMY7G9N9zt kmxsYMGUyjs3gzW1HHXcxkMwPZ6NwyvaxZY2JmX9F3Xt6ubG5afHdrX1/5Rv1IRIuVT3 Wg+yGRWTd+NVEpxvqso7rGso9gg2FpihKMELMJTwP5bDg7LAJL/KpyfJQrvSNOnyGgrq x7zPiT2ZvcCAu+Ngx6MdNsC+ADpuGvOfBKjk/Xex2U6qNhB6B/bt5UeT7VkDoOXhkzUE lrdKApJfbTLei9YYkf4fC2zt9a1p0hprez8ZvT0ea8JzT/+stnknHBu1vlKQwPQYJZR9 Htvg== X-Gm-Message-State: APjAAAUyKuO2WwCFjIuqZntxXyH1fz5eUwN2XkgSAkMHsNRdCmftL/xC l3s5sjfieGwISL+kyzFohuA= X-Google-Smtp-Source: APXvYqyrxrWm6rhJSwzRVJAsMRHqTij9c7qVsUL/yEXgQ9HFAOZxBfWRBLF6+bXWF7lsU2vFs11LmA== X-Received: by 2002:a05:600c:20e:: with SMTP id 14mr3191543wmi.104.1581667940936; Fri, 14 Feb 2020 00:12:20 -0800 (PST) Received: from andrea (ip-213-220-200-127.net.upcbroadband.cz. [213.220.200.127]) by smtp.gmail.com with ESMTPSA id x10sm5847657wrv.60.2020.02.14.00.12.19 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 14 Feb 2020 00:12:20 -0800 (PST) Date: Fri, 14 Feb 2020 09:12:13 +0100 From: Andrea Parri To: Boqun Feng Cc: linux-kernel@vger.kernel.org, Alan Stern , Will Deacon , Peter Zijlstra , Nicholas Piggin , David Howells , Jade Alglave , Luc Maranget , "Paul E. McKenney" , Akira Yokosawa , Daniel Lustig , Jonathan Corbet , linux-arch@vger.kernel.org, linux-doc@vger.kernel.org Subject: Re: [RFC 2/3] tools/memory-model: Add a litmus test for atomic_set() Message-ID: <20200214081213.GA17708@andrea> References: <20200214040132.91934-1-boqun.feng@gmail.com> <20200214040132.91934-3-boqun.feng@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200214040132.91934-3-boqun.feng@gmail.com> User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org > @@ -0,0 +1,24 @@ > +C Atomic-set-observable-to-RMW > + > +(* > + * Result: Never > + * > + * Test of the result of atomic_set() must be observable to atomic RMWs. > + *) > + > +{ > + atomic_t v = ATOMIC_INIT(1); > +} > + > +P0(atomic_t *v) > +{ > + (void)atomic_add_unless(v,1,0); We blacklisted this primitive some time ago, cf. section "LIMITATIONS", entry (6b) in tools/memory-model/README; the discussion was here: https://lkml.kernel.org/r/20180829211053.20531-3-paulmck@linux.vnet.ibm.com but unfortunately I can't remember other details at the moment: maybe it is just a matter of or the proper time to update that section. Thanks, Andrea