Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753786AbbBMPwo (ORCPT ); Fri, 13 Feb 2015 10:52:44 -0500 Received: from foss-mx-na.arm.com ([217.140.108.86]:43586 "EHLO foss-mx-na.foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753025AbbBMPwn (ORCPT ); Fri, 13 Feb 2015 10:52:43 -0500 Date: Fri, 13 Feb 2015 15:52:08 +0000 From: Mark Rutland To: Stephen Boyd Cc: Russell King - ARM Linux , "Paul E. McKenney" , Krzysztof Kozlowski , "linux-arm-kernel@lists.infradead.org" , "linux-kernel@vger.kernel.org" , Arnd Bergmann , Bartlomiej Zolnierkiewicz , Marek Szyprowski , Catalin Marinas , Will Deacon Subject: Re: [PATCH v2] ARM: Don't use complete() during __cpu_die Message-ID: <20150213155208.GG10496@leverpostej> References: <1423131270-24047-1-git-send-email-k.kozlowski@samsung.com> <20150205105035.GL8656@n2100.arm.linux.org.uk> <20150205142918.GA10634@linux.vnet.ibm.com> <20150205161100.GQ8656@n2100.arm.linux.org.uk> <54D95DB8.9010308@codeaurora.org> <20150210151416.GD9432@leverpostej> <54DA6E92.3090109@codeaurora.org> <54DA725E.6080305@codeaurora.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <54DA725E.6080305@codeaurora.org> 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 Content-Length: 3405 Lines: 102 [...] > > Aside: For that last row we really should be setting cpu->hotpluggable > > in struct cpu based on what cpu_ops::cpu_disable returns (from what I > > can tell we use that op to indicate if a CPU can be hotplugged). > > > > There's a patch for that (tm). > > ----8<---- > > From: Stephen Boyd > Subject: [PATCH] ARM: smp: Only expose /sys/.../cpuX/online if hotpluggable > > Writes to /sys/.../cpuX/online fail if we determine the platform > doesn't support hotplug for that CPU. Let's figure this out > befoer we make the sysfs nodes so that the online file doesn't > even exist if it's not possible to hotplug the CPU. > > Signed-off-by: Stephen Boyd > --- > arch/arm/include/asm/smp.h | 6 ++++++ > arch/arm/kernel/setup.c | 2 +- > arch/arm/kernel/smp.c | 11 ++++------- > 3 files changed, 11 insertions(+), 8 deletions(-) > > diff --git a/arch/arm/include/asm/smp.h b/arch/arm/include/asm/smp.h > index 18f5a554134f..9f82430efd59 100644 > --- a/arch/arm/include/asm/smp.h > +++ b/arch/arm/include/asm/smp.h > @@ -123,4 +123,10 @@ struct of_cpu_method { > */ > extern void smp_set_ops(struct smp_operations *); > > +#ifdef CONFIG_HOTPLUG_CPU > +extern int platform_can_hotplug_cpu(unsigned int cpu); > +#else > +static inline int platform_can_hotplug_cpu(unsigned int cpu) { return 0; } > +#endif > + > #endif /* ifndef __ASM_ARM_SMP_H */ > diff --git a/arch/arm/kernel/setup.c b/arch/arm/kernel/setup.c > index 715ae19bc7c8..c61c09defc78 100644 > --- a/arch/arm/kernel/setup.c > +++ b/arch/arm/kernel/setup.c > @@ -974,7 +974,7 @@ static int __init topology_init(void) > > for_each_possible_cpu(cpu) { > struct cpuinfo_arm *cpuinfo = &per_cpu(cpu_data, cpu); > - cpuinfo->cpu.hotpluggable = 1; > + cpuinfo->cpu.hotpluggable = platform_can_hotplug_cpu(cpu); > register_cpu(&cpuinfo->cpu, cpu); > } > > diff --git a/arch/arm/kernel/smp.c b/arch/arm/kernel/smp.c > index fe0386c751b2..4d213b24db60 100644 > --- a/arch/arm/kernel/smp.c > +++ b/arch/arm/kernel/smp.c > @@ -174,18 +174,19 @@ static int platform_cpu_kill(unsigned int cpu) > return 1; > } > > -static int platform_cpu_disable(unsigned int cpu) > +int platform_can_hotplug_cpu(unsigned int cpu) > { > if (smp_ops.cpu_disable) > - return smp_ops.cpu_disable(cpu); > + return smp_ops.cpu_disable(cpu) ? 0 : 1; > > /* > * By default, allow disabling all CPUs except the first one, > * since this is special on a lot of platforms, e.g. because > * of clock tick interrupts. > */ > - return cpu == 0 ? -EPERM : 0; > + return cpu == 0 ? 0 : 1; > } > + > /* > * __cpu_disable runs on the processor to be shutdown. > */ > @@ -194,10 +195,6 @@ int __cpu_disable(void) > unsigned int cpu = smp_processor_id(); > int ret; > > - ret = platform_cpu_disable(cpu); > - if (ret) > - return ret; For PSCI 0.2+ I was hoping to hook the MIGRATE logic in here. The secure side may reject hotplugging of a CPU, but it's a dynamic property of the system and so can't be probed once at boot time. I guess when I manage to get around to that I can restore a hook here. Thanks, Mark. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/