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=-2.4 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_PASS, USER_AGENT_MUTT autolearn=ham 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 6168FC2BC61 for ; Mon, 29 Oct 2018 05:16:15 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 3EC042064C for ; Mon, 29 Oct 2018 05:16:14 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=amarulasolutions.com header.i=@amarulasolutions.com header.b="YpeMC0Yh" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 3EC042064C Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=amarulasolutions.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729149AbeJ2ODQ (ORCPT ); Mon, 29 Oct 2018 10:03:16 -0400 Received: from mail-ed1-f41.google.com ([209.85.208.41]:33755 "EHLO mail-ed1-f41.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729098AbeJ2ODQ (ORCPT ); Mon, 29 Oct 2018 10:03:16 -0400 Received: by mail-ed1-f41.google.com with SMTP id f1-v6so6146310edi.0 for ; Sun, 28 Oct 2018 22:16:11 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=amarulasolutions.com; s=google; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to:user-agent; bh=L8BmDcfIMNiHcYqq+EUNU6oRwocIp+IIN3LOuA/7ZIQ=; b=YpeMC0YhLurmQEdtsF7TPTr5KQLDXyqOUusmVfCynFSFT8AQ25xz0/NZC2/XsKGXLK KTODxi9MRyPD2Nu8T/hjDyVtLI7b6GMxSXhMa954BySqCfWBz1d2oiyqiujg5rP2lmM4 rXHPlHkqjyDJaLEk36W4y3pC1PY1U/2LOUAAo= 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=L8BmDcfIMNiHcYqq+EUNU6oRwocIp+IIN3LOuA/7ZIQ=; b=cIjBgQjo5QQtXUdk2uX242QerlGo4c8/QSZw0gFzMISoCZJGxhcGXvE1e7e1eNBSH9 RoPv7uD63LtvV63g6UsdEBuROIXb29ijgX8r3oAGxartp2Bl33h8OS/x5pJA1yDtk2gV MlYwRYi6I5po0/ZKWAlqUYQCVPS3LxRo9HaUu27x5Emx86LplOtYaY6Q80pGX0HMXaap c3fsWNad+4pOnPYCxhBCNrrF3OTzrJsxS2cGoQwLs66pKQYrLtj5+kby8lnk1Wif4iBL idMaY7oGQ+bNLnBgWfRXF/N4iLclVDt428hbZVy3yK29Fk1O1+M3K/4TT9BHGaVIbkjo ZmUw== X-Gm-Message-State: AGRZ1gIjFWJin9JFcmPrsVKubEkdvq+7iyKgfRtQwf8kkDwo2/XroGVt AnYUiZJJ6MP4GwNZ+HQmvtpAHNwfFafcPw== X-Google-Smtp-Source: AJdET5cCXwnZ+FquqWm+n8IYqOKTTWP2WUdVdPXaBuor4LVmci/QhEio5kn69ADMxyhZzUN88reMXw== X-Received: by 2002:a17:906:3fd3:: with SMTP id k19-v6mr4275714ejj.158.1540790170555; Sun, 28 Oct 2018 22:16:10 -0700 (PDT) Received: from andrea (15.152.230.94.awnet.cz. [94.230.152.15]) by smtp.gmail.com with ESMTPSA id b7-v6sm5386581edd.43.2018.10.28.22.16.08 (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Sun, 28 Oct 2018 22:16:09 -0700 (PDT) Date: Mon, 29 Oct 2018 06:16:02 +0100 From: Andrea Parri To: "Paul E. McKenney" Cc: Peter Zijlstra , Josh Triplett , linux-kernel@vger.kernel.org Subject: Re: [RFR] Store tearing Message-ID: <20181029051602.GA3358@andrea> References: <20181028230627.GA3420@andrea> <20181028231003.GA4021@andrea> <20181029012042.GR4170@linux.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20181029012042.GR4170@linux.ibm.com> User-Agent: Mutt/1.9.4 (2018-02-28) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sun, Oct 28, 2018 at 06:20:42PM -0700, Paul E. McKenney wrote: > On Mon, Oct 29, 2018 at 12:10:03AM +0100, Andrea Parri wrote: > > Hopefully, with Paul's proper email address this time, > > > > Andrea > > > > On Mon, Oct 29, 2018 at 12:06:27AM +0100, Andrea Parri wrote: > > > Hi, > > > > > > memory-barriers.txt says: > > > > > > [on "store tearing"] > > > > > > "In fact, a recent bug (since fixed) caused GCC to incorrectly use > > > this optimization in a volatile store.". > > > > > > I was wondering if you could help me retrieve some reference/discussions > > > about this? > > This was quite some time ago, but it involved a 32-bit volatile store > of a constant such as 0x10001. The machine in question had a narrow > store-immediate instruction, so the compiler emitted a pair of 16-bit > store-immediate instructions. This bug was fixed, though only after > significant screaming and shouting. That does sound like an interesting discussion. ;D Thanks for the info, Andrea > > Thanx, Paul >