From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752655AbbBRX2B (ORCPT ); Wed, 18 Feb 2015 18:28:01 -0500 Received: from smtp.codeaurora.org ([198.145.29.96]:44901 "EHLO smtp.codeaurora.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752192AbbBRX2A (ORCPT ); Wed, 18 Feb 2015 18:28:00 -0500 Message-ID: <54E51FFD.7080506@codeaurora.org> Date: Wed, 18 Feb 2015 15:27:57 -0800 From: Stephen Boyd User-Agent: Mozilla/5.0 (X11; Linux i686 on x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.4.0 MIME-Version: 1.0 To: Simon Horman CC: Russell King , linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, Mark Rutland , Nicolas Pitre , Dave Martin , Magnus Damm , linux-sh@vger.kernel.org Subject: Re: [PATCH v3] ARM: smp: Only expose /sys/.../cpuX/online if hotpluggable References: <1423874574-3494-1-git-send-email-sboyd@codeaurora.org> <20150218222731.GC24177@verge.net.au> In-Reply-To: <20150218222731.GC24177@verge.net.au> Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 02/18/15 14:27, Simon Horman wrote: > On Fri, Feb 13, 2015 at 04:42:54PM -0800, Stephen Boyd wrote: >> Writes to /sys/.../cpuX/online fail if we determine the platform >> doesn't support hotplug for that CPU. Furthermore, if the cpu_die >> op isn't specified the system hangs when we try to offline a CPU >> and it comes right back online unexpectedly. Let's figure this >> stuff out before we make the sysfs nodes so that the online file >> doesn't even exist if it isn't (at least sometimes) possible to >> hotplug the CPU. >> >> Add a new cpu_can_disable op and repoint all cpu_disable >> implementations at it because all current users use the op to >> indicate if a CPU can be hotplugged or not in a static fashion. >> With PSCI we may need to introduce a cpu_disable op so that the >> secure OS can be migrated off the CPU we're trying to hotplug. >> In this case, the cpu_can_disable op will indicate that all CPUs >> are hotpluggable by returning 1, but the cpu_disable op will make >> a PSCI migration call and occasionally fail, denying the hotplug >> of a CPU. This shouldn't be any worse than x86 where we may >> indicate that all CPUs are hotpluggable but occasionally we can't >> offline a CPU due to check_irq_vectors_for_cpu_disable() failing >> to find a CPU to move vectors to. >> >> Cc: Mark Rutland >> Cc: Nicolas Pitre >> Cc: Dave Martin >> Cc: Simon Horman >> Cc: Magnus Damm >> Cc: >> Signed-off-by: Stephen Boyd >> --- >> >> Changes since v2: >> * Left cpu_disable op in place >> * Split out shmobile function deletion >> >> arch/arm/common/mcpm_platsmp.c | 12 ++++-------- >> arch/arm/include/asm/smp.h | 10 ++++++++++ >> arch/arm/kernel/setup.c | 2 +- >> arch/arm/kernel/smp.c | 15 ++++++++++++++- >> arch/arm/mach-shmobile/common.h | 2 +- >> arch/arm/mach-shmobile/platsmp.c | 4 ++-- >> arch/arm/mach-shmobile/smp-r8a7790.c | 2 +- >> arch/arm/mach-shmobile/smp-r8a7791.c | 2 +- >> arch/arm/mach-shmobile/smp-sh73a0.c | 2 +- >> 9 files changed, 35 insertions(+), 16 deletions(-) > I think it would make sense to separate the ARM-core changes > from the mach-shmobile integration changes. Are you saying two (three?) patches to add the op, and then move over each struct smp_operations? It's all going through rmk's tree so I'll leave that up to him. -- Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, a Linux Foundation Collaborative Project