Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752181AbaBJA43 (ORCPT ); Sun, 9 Feb 2014 19:56:29 -0500 Received: from mail-ve0-f180.google.com ([209.85.128.180]:61871 "EHLO mail-ve0-f180.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751760AbaBJA41 (ORCPT ); Sun, 9 Feb 2014 19:56:27 -0500 MIME-Version: 1.0 In-Reply-To: <1391992071.18779.99.camel@triegel.csb> References: <52F3DA85.1060209@arm.com> <20140206185910.GE27276@mudshark.cambridge.arm.com> <20140206192743.GH4250@linux.vnet.ibm.com> <1391721423.23421.3898.camel@triegel.csb> <20140206221117.GJ4250@linux.vnet.ibm.com> <1391730288.23421.4102.camel@triegel.csb> <20140207042051.GL4250@linux.vnet.ibm.com> <20140207074405.GM5002@laptop.programming.kicks-ass.net> <20140207165028.GO4250@linux.vnet.ibm.com> <20140207165548.GR5976@mudshark.cambridge.arm.com> <20140207180216.GP4250@linux.vnet.ibm.com> <1391992071.18779.99.camel@triegel.csb> Date: Sun, 9 Feb 2014 16:56:26 -0800 X-Google-Sender-Auth: 3W8wPEa-zcdE2SC-JaOO91otoeg Message-ID: Subject: Re: [RFC][PATCH 0/5] arch: atomic rework From: Linus Torvalds To: Torvald Riegel Cc: Paul McKenney , Will Deacon , Peter Zijlstra , Ramana Radhakrishnan , David Howells , "linux-arch@vger.kernel.org" , "linux-kernel@vger.kernel.org" , "akpm@linux-foundation.org" , "mingo@kernel.org" , "gcc@gcc.gnu.org" Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sun, Feb 9, 2014 at 4:27 PM, Torvald Riegel wrote: > > I wouldn't characterize the situation like this (although I can't speak > for others, obviously). IMHO, it's perfectly fine on sequential / > non-synchronizing code, because we know the difference isn't observable > by a correct program. What BS is that? If you use an "atomic_store_explicit()", by definition you're either (a) f*cking insane (b) not doing sequential non-synchronizing code and a compiler that assumes that the programmer is insane may actually be correct more often than not, but it's still a shit compiler. Agreed? So I don't see how any sane person can say that speculative writes are ok. They are clearly not ok. Speculative stores are a bad idea in general. They are completely invalid for anything that says "atomic". This is not even worth discussing. Linus -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/