From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932122AbdJJJsk (ORCPT ); Tue, 10 Oct 2017 05:48:40 -0400 Received: from ozlabs.org ([103.22.144.67]:50965 "EHLO ozlabs.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932081AbdJJJsi (ORCPT ); Tue, 10 Oct 2017 05:48:38 -0400 From: Michael Ellerman To: Thomas Gleixner , Thiago Jung Bauermann Cc: Daniel Black , linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] powerpc: Drop lockdep_assert_cpus_held call from arch_update_cpu_topology In-Reply-To: References: <20171005000430.8080-1-bauerman@linux.vnet.ibm.com> <87o9pl5u4m.fsf@linux.vnet.ibm.com> Date: Tue, 10 Oct 2017 20:48:36 +1100 Message-ID: <87o9pfwcy3.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 Thomas Gleixner writes: ... > > So no, the lockdep assertion triggers in #1 and #2 because > > #1 does definitely not hold it > > #2 is indirectily protected, but we have no way to express that to lockdep > > So yes, it's safe for both cases to remove that assertion. Thanks for clarifying that. > If there are other call sites, then they need to be checked. If not, you're > good. I also see a call in partition_sched_domains(). The comment there says "call with hotplug lock held" and I'm sure all callers do so ... But seriously I think the patch is good because we know there are at least two callers who are safe but can't hold the lock, so doing an assert there is definitely wrong. So I'll apply the patch with a slightly reworked commit message. cheers