Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752128AbaFBRd5 (ORCPT ); Mon, 2 Jun 2014 13:33:57 -0400 Received: from g2t2354.austin.hp.com ([15.217.128.53]:18859 "EHLO g2t2354.austin.hp.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751511AbaFBRdz (ORCPT ); Mon, 2 Jun 2014 13:33:55 -0400 Message-ID: <538CB56E.5010709@hp.com> Date: Mon, 02 Jun 2014 13:33:34 -0400 From: Waiman Long User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:10.0.12) Gecko/20130109 Thunderbird/10.0.12 MIME-Version: 1.0 To: Peter Zijlstra CC: Mikulas Patocka , Linus Torvalds , jejb@parisc-linux.org, deller@gmx.de, John David Anglin , linux-parisc@vger.kernel.org, linux-kernel@vger.kernel.org, paulmck@linux.vnet.ibm.com, chegu_vinod@hp.com, tglx@linutronix.de, riel@redhat.com, akpm@linux-foundation.org, davidlohr@hp.com, hpa@zytor.com, andi@firstfloor.org, aswin@hp.com, scott.norton@hp.com, Jason Low Subject: Re: [PATCH v2] introduce atomic_pointer to fix a race condition in cancelable mcs spinlocks References: <20140602162525.GH16155@laptop.programming.kicks-ass.net> <20140602163032.GI16155@laptop.programming.kicks-ass.net> In-Reply-To: <20140602163032.GI16155@laptop.programming.kicks-ass.net> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 06/02/2014 12:30 PM, Peter Zijlstra wrote: > On Mon, Jun 02, 2014 at 06:25:25PM +0200, Peter Zijlstra wrote: >> I'm almost inclined to just exclude parisc from using opt spinning. >> >> That said, this patch still doesn't address the far more interesting >> problem of actually finding these issues for these few weird archs. > So why do these archs provide xchg() and cmpxchg() at all? Wouldn't it > be much simpler if archs that cannot sanely do this, not provide these > primitives at all? I believe xchg() and cmpxchg() are used in quite a number of places within the generic kernel code. So kernel compilation will fail if those APIs aren't provided by an architecture. -Longman -- 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/