From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754052AbcHVIdr (ORCPT ); Mon, 22 Aug 2016 04:33:47 -0400 Received: from mx2.suse.de ([195.135.220.15]:49338 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750839AbcHVIdp (ORCPT ); Mon, 22 Aug 2016 04:33:45 -0400 Date: Mon, 22 Aug 2016 10:33:42 +0200 From: Petr Mladek To: Chris Metcalf Cc: Peter Zijlstra , "Rafael J. Wysocki" , Russell King , Thomas Gleixner , Aaron Tomlin , Ingo Molnar , Andrew Morton , Daniel Thompson , "Ralf Baechle ralf @ linux-mips . org David S. Miller" , linux-mips@linux-mips.org, sparclinux@vger.kernel.org, x86@kernel.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v8 1/4] nmi_backtrace: add more trigger_*_cpu_backtrace() methods Message-ID: <20160822083342.GA4866@pathway.suse.cz> References: <1471377024-2244-1-git-send-email-cmetcalf@mellanox.com> <1471377024-2244-2-git-send-email-cmetcalf@mellanox.com> <20160818141242.GK26194@pathway.suse.cz> <233b9270-2f35-b3c5-2520-bf513153f260@mellanox.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <233b9270-2f35-b3c5-2520-bf513153f260@mellanox.com> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri 2016-08-19 21:54:31, Chris Metcalf wrote: > On 8/18/2016 10:12 AM, Petr Mladek wrote: > >On Tue 2016-08-16 15:50:21, Chris Metcalf wrote: > >>Currently you can only request a backtrace of either all cpus, or > >>all cpus but yourself. It can also be helpful to request a remote > >>backtrace of a single cpu, and since we want that, the logical > >>extension is to support a cpumask as the underlying primitive. > >> > >>This change modifies the existing lib/nmi_backtrace.c code to take > >>a cpumask as its basic primitive, and modifies the linux/nmi.h code > >>to use the new "cpumask" method instead. > >> > >>The mips code ignored the "include_self" boolean but with this change > >>it will now also dump a local backtrace if requested. > >> > >>diff --git a/arch/mips/kernel/process.c b/arch/mips/kernel/process.c > >>index 7429ad09fbe3..fea1fa7726e3 100644 > >>--- a/arch/mips/kernel/process.c > >>+++ b/arch/mips/kernel/process.c > >>@@ -569,9 +569,16 @@ static void arch_dump_stack(void *info) > >> dump_stack(); > >> } > >>-void arch_trigger_all_cpu_backtrace(bool include_self) > >>+void arch_trigger_cpumask_backtrace(const cpumask_t *mask, bool exclude_self) > >> { > >>- smp_call_function(arch_dump_stack, NULL, 1); > >>+ long this_cpu = get_cpu(); > >>+ > >>+ if (cpumask_test_cpu(this_cpu, mask) && !exclude_self) > >>+ dump_stack(); > >The bit is not cleared in the mask. Therefore arch_dump_stack > >will get called for this CPU as well. > > Actually, and kind of confusingly, smp_call_function_many() never calls > the current cpu, even if it is in the mask. So this code is OK as-is. I see it now. > >Otherwise the patch patch looks good to me. > > Great, thanks! Should I add your Reviewed-by? Yup. This patch looks fine then: Reviewed-by: Petr Mladek Best Regards, Petr