From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751679AbeDDK2n (ORCPT ); Wed, 4 Apr 2018 06:28:43 -0400 Received: from ozlabs.org ([103.22.144.67]:58607 "EHLO ozlabs.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751573AbeDDK2i (ORCPT ); Wed, 4 Apr 2018 06:28:38 -0400 Authentication-Results: ozlabs.org; dmarc=none (p=none dis=none) header.from=ellerman.id.au From: Michael Ellerman To: Peter Zijlstra Cc: Andrea Parri , Benjamin Herrenschmidt , Paul Mackerras , Ingo Molnar , linux-kernel@vger.kernel.org, Linus Torvalds Subject: Re: [PATCH for-4.17 2/2] powerpc: Remove smp_mb() from arch_spin_is_locked() In-Reply-To: <20180328110809.GE4129@hirez.programming.kicks-ass.net> References: <1522060667-7034-1-git-send-email-andrea.parri@amarulasolutions.com> <1522109216.7364.30.camel@kernel.crashing.org> <20180327102521.GA7347@andrea> <87a7us3h66.fsf@concordia.ellerman.id.au> <20180328110436.GR4043@hirez.programming.kicks-ass.net> <20180328110809.GE4129@hirez.programming.kicks-ass.net> Date: Wed, 04 Apr 2018 20:28:36 +1000 Message-ID: <87tvsrmfjf.fsf@concordia.ellerman.id.au> MIME-Version: 1.0 Content-Type: text/plain Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Peter Zijlstra writes: > On Wed, Mar 28, 2018 at 01:04:36PM +0200, Peter Zijlstra wrote: >> On Wed, Mar 28, 2018 at 04:25:37PM +1100, Michael Ellerman wrote: >> > Documenting it would definitely be good, but even then I'd be inclined >> > to leave the barrier in our implementation. Matching the documented >> > behaviour is one thing, but the actual real-world behaviour on well >> > tested platforms (ie. x86) is more important. >> >> By that argument you should switch your spinlock implementation to RCpc >> and include that SYNC in either lock or unlock already ;-) > > *RCsc* obviously... clearly I need to wake up moar. It's just a jumble of letters to me - I didn't even notice ;) cheers