From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759522Ab1JGDOF (ORCPT ); Thu, 6 Oct 2011 23:14:05 -0400 Received: from terminus.zytor.com ([198.137.202.10]:53686 "EHLO mail.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1759479Ab1JGDOD (ORCPT ); Thu, 6 Oct 2011 23:14:03 -0400 References: <1317945508-19575-1-git-send-email-jistone@redhat.com> <990b8719-066b-4e1d-892f-6a3ea4241fb2@email.android.com> User-Agent: K-9 Mail for Android In-Reply-To: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Subject: Re: [PATCH] x86: Make variable_test_bit reference all of *addr From: "hpanvin@gmail.com" Date: Thu, 06 Oct 2011 20:13:38 -0700 To: Andi Kleen CC: Josh Stone , linux-kernel@vger.kernel.org, Thomas Gleixner , Ingo Molnar , x86@kernel.org, Masami Hiramatsu , Srikar Dronamraju , Jakub Jelinek Message-ID: <9d5b1868-51f5-4d88-8b0e-813e32b05a96@email.android.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Memory clobbers are universal producers, not consumers. Andi Kleen wrote: >"hpanvin@gmail.com" writes: > > >> This is concerning... the kernel relies heavily on asm volatile being >a universal memory consumer. If that is suddenly broken, we are f*** >in many, many, MANY places in the kernel all of a sudden! > >I don't think that's true. We generally add "memory" clobbers for this >purpose. asm volatile just means "don't move" > >Just this one doesn't have it for unknown reasons (someone >overoptimizing?) > >-Andi > >-- >ak@linux.intel.com -- Speaking for myself only -- Sent from my Android phone with K-9 Mail. Please excuse my brevity.