From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pb0-f46.google.com (mail-pb0-f46.google.com [209.85.160.46]) by kanga.kvack.org (Postfix) with ESMTP id 1A4416B00B0 for ; Fri, 27 Sep 2013 10:05:09 -0400 (EDT) Received: by mail-pb0-f46.google.com with SMTP id rq2so2614514pbb.33 for ; Fri, 27 Sep 2013 07:05:08 -0700 (PDT) Message-ID: <1380290700.17366.95.camel@joe-AO722> Subject: Re: [PATCH v6 5/6] MCS Lock: Restructure the MCS lock defines and locking code into its own file From: Joe Perches Date: Fri, 27 Sep 2013 07:05:00 -0700 In-Reply-To: <20130927134802.GA15690@laptop.programming.kicks-ass.net> References: <1380226007.2170.2.camel@buesod1.americas.hpqcorp.net> <1380226997.2602.11.camel@j-VirtualBox> <1380228059.2170.10.camel@buesod1.americas.hpqcorp.net> <1380229794.2602.36.camel@j-VirtualBox> <1380231702.3467.85.camel@schen9-DESK> <1380235333.3229.39.camel@j-VirtualBox> <1380236265.3467.103.camel@schen9-DESK> <20130927060213.GA6673@gmail.com> <20130927112323.GJ3657@laptop.programming.kicks-ass.net> <1380289495.17366.91.camel@joe-AO722> <20130927134802.GA15690@laptop.programming.kicks-ass.net> Content-Type: text/plain; charset="ISO-8859-1" Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Peter Zijlstra Cc: Ingo Molnar , Tim Chen , Jason Low , Davidlohr Bueso , Ingo Molnar , Andrew Morton , Andrea Arcangeli , Alex Shi , Andi Kleen , Michel Lespinasse , Davidlohr Bueso , Matthew R Wilcox , Dave Hansen , Rik van Riel , Peter Hurley , linux-kernel@vger.kernel.org, linux-mm On Fri, 2013-09-27 at 15:48 +0200, Peter Zijlstra wrote: > On Fri, Sep 27, 2013 at 06:44:55AM -0700, Joe Perches wrote: > > It's a CHK test, so it's only tested with --strict > > > > $ scripts/checkpatch.pl -f --strict kernel/mutex.c 2>&1 | grep memory > > CHECK: memory barrier without comment > > CHECK: memory barrier without comment > > > > It could be changed to WARN so it's always on. > > Yes please, we can't be too careful with memory barriers. I'll send the patch separately. It seems a pretty noisy test. There are 13 hits just in arch/x86/kernel/ $ ./scripts/checkpatch.pl -f arch/x86/kernel/*.c | grep -A3 "memory barrier" WARNING: memory barrier without comment #685: FILE: x86/kernel/alternative.c:685: + smp_wmb(); -- WARNING: memory barrier without comment #401: FILE: x86/kernel/kvm.c:401: + rmb(); WARNING: memory barrier without comment #403: FILE: x86/kernel/kvm.c:403: + rmb(); -- WARNING: memory barrier without comment #702: FILE: x86/kernel/kvm.c:702: + smp_wmb(); WARNING: memory barrier without comment #704: FILE: x86/kernel/kvm.c:704: + smp_wmb(); -- WARNING: memory barrier without comment #62: FILE: x86/kernel/ldt.c:62: + wmb(); WARNING: memory barrier without comment #64: FILE: x86/kernel/ldt.c:64: + wmb(); -- WARNING: memory barrier without comment #204: FILE: x86/kernel/smpboot.c:204: + wmb(); WARNING: memory barrier without comment #265: FILE: x86/kernel/smpboot.c:265: + wmb(); -- WARNING: memory barrier without comment #557: FILE: x86/kernel/smpboot.c:557: + mb(); -- WARNING: memory barrier without comment #1065: FILE: x86/kernel/smpboot.c:1065: + mb(); -- WARNING: memory barrier without comment #1321: FILE: x86/kernel/smpboot.c:1321: + mb(); WARNING: memory barrier without comment #1399: FILE: x86/kernel/smpboot.c:1399: + mb(); -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org