From patchwork Tue Apr 7 17:58:00 2015 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Stephen Boyd X-Patchwork-Id: 6174311 Return-Path: X-Original-To: patchwork-linux-arm@patchwork.kernel.org Delivered-To: patchwork-parsemail@patchwork1.web.kernel.org Received: from mail.kernel.org (mail.kernel.org [198.145.29.136]) by patchwork1.web.kernel.org (Postfix) with ESMTP id 387729F2EC for ; Tue, 7 Apr 2015 18:01:05 +0000 (UTC) Received: from mail.kernel.org (localhost [127.0.0.1]) by mail.kernel.org (Postfix) with ESMTP id 1AF8720381 for ; Tue, 7 Apr 2015 18:01:04 +0000 (UTC) Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.9]) (using TLSv1.2 with cipher DHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id E84E820295 for ; Tue, 7 Apr 2015 18:01:02 +0000 (UTC) Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.80.1 #2 (Red Hat Linux)) id 1YfXlp-0004SC-9K; Tue, 07 Apr 2015 17:58:41 +0000 Received: from smtp.codeaurora.org ([198.145.29.96]) by bombadil.infradead.org with esmtps (Exim 4.80.1 #2 (Red Hat Linux)) id 1YfXlX-0004FI-Kf for linux-arm-kernel@lists.infradead.org; Tue, 07 Apr 2015 17:58:25 +0000 Received: from smtp.codeaurora.org (localhost [127.0.0.1]) by smtp.codeaurora.org (Postfix) with ESMTP id 356FE141093; Tue, 7 Apr 2015 17:58:02 +0000 (UTC) Received: by smtp.codeaurora.org (Postfix, from userid 486) id 2186514108E; Tue, 7 Apr 2015 17:58:02 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on mail.kernel.org X-Spam-Level: X-Spam-Status: No, score=-4.2 required=5.0 tests=BAYES_00, RCVD_IN_DNSWL_MED, T_RP_MATCHES_RCVD, UNPARSEABLE_RELAY autolearn=unavailable version=3.3.1 Received: from [10.134.64.202] (i-global254.qualcomm.com [199.106.103.254]) (using TLSv1.2 with cipher DHE-RSA-AES128-SHA (128/128 bits)) (No client certificate requested) (Authenticated sender: sboyd@smtp.codeaurora.org) by smtp.codeaurora.org (Postfix) with ESMTPSA id BCE5914108E; Tue, 7 Apr 2015 17:58:00 +0000 (UTC) Message-ID: <55241AA8.8060208@codeaurora.org> Date: Tue, 07 Apr 2015 10:58:00 -0700 From: Stephen Boyd User-Agent: Mozilla/5.0 (X11; Linux i686 on x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.5.0 MIME-Version: 1.0 To: Tyler Baker Subject: Re: [PATCH v4] ARM: smp: Only expose /sys/.../cpuX/online if hotpluggable References: <1428351853-5844-1-git-send-email-sboyd@codeaurora.org> In-Reply-To: X-Virus-Scanned: ClamAV using ClamSMTP X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20150407_105823_772261_03D0F418 X-CRM114-Status: GOOD ( 26.91 ) X-Spam-Score: -0.0 (/) Cc: Mark Rutland , Russell King , Nicolas Pitre , "linux-sh@vger.kernel.org" , Magnus Damm , "linux-kernel@vger.kernel.org" , Simon Horman , Geert Uytterhoeven , Dave Martin , linux-arm-kernel X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.18-1 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+patchwork-linux-arm=patchwork.kernel.org@lists.infradead.org X-Virus-Scanned: ClamAV using ClamSMTP On 04/07/15 09:18, Tyler Baker wrote: > Hi Stephen, > > On 6 April 2015 at 13:24, 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 implementers use the op to >> indicate if a CPU can be hotplugged or not in a static fashion. >> With PSCI we may need to add 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 true, 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: >> Cc: Tyler Baker >> Cc: Geert Uytterhoeven >> Signed-off-by: Stephen Boyd >> --- >> >> Changes since v3: >> * Return bool instead of int from 'cpu_can_disable' op >> >> 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(-) >> >> diff --git a/arch/arm/common/mcpm_platsmp.c b/arch/arm/common/mcpm_platsmp.c >> index 92e54d7c6f46..2b25b6038f66 100644 >> --- a/arch/arm/common/mcpm_platsmp.c >> +++ b/arch/arm/common/mcpm_platsmp.c >> @@ -65,14 +65,10 @@ static int mcpm_cpu_kill(unsigned int cpu) >> return !mcpm_wait_for_cpu_powerdown(pcpu, pcluster); >> } >> >> -static int mcpm_cpu_disable(unsigned int cpu) >> +static bool mcpm_cpu_can_disable(unsigned int cpu) >> { >> - /* >> - * We assume all CPUs may be shut down. >> - * This would be the hook to use for eventual Secure >> - * OS migration requests as described in the PSCI spec. >> - */ >> - return 0; >> + /* We assume all CPUs may be shut down. */ >> + return true; >> } >> >> static void mcpm_cpu_die(unsigned int cpu) >> @@ -92,7 +88,7 @@ static struct smp_operations __initdata mcpm_smp_ops = { >> .smp_secondary_init = mcpm_secondary_init, >> #ifdef CONFIG_HOTPLUG_CPU >> .cpu_kill = mcpm_cpu_kill, >> - .cpu_disable = mcpm_cpu_disable, >> + .cpu_can_disable = mcpm_cpu_can_disable, >> .cpu_die = mcpm_cpu_die, >> #endif >> }; >> diff --git a/arch/arm/include/asm/smp.h b/arch/arm/include/asm/smp.h >> index 18f5a554134f..e15856a1a380 100644 >> --- a/arch/arm/include/asm/smp.h >> +++ b/arch/arm/include/asm/smp.h >> @@ -104,6 +104,7 @@ struct smp_operations { >> #ifdef CONFIG_HOTPLUG_CPU >> int (*cpu_kill)(unsigned int cpu); >> void (*cpu_die)(unsigned int cpu); >> + bool (*cpu_can_disable)(unsigned int cpu); >> int (*cpu_disable)(unsigned int cpu); >> #endif >> #endif >> @@ -123,4 +124,13 @@ 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 6c777e908a24..955d45d0f70c 100644 >> --- a/arch/arm/kernel/setup.c >> +++ b/arch/arm/kernel/setup.c >> @@ -992,7 +992,7 @@ 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); >> } >> > When I tested this patch before I only tried building > multi_v7_defconfig (which built fine) however I've added this patch to > my to-build branch and sent it through the CI loop. It appears that > there quite a few build errors on the other defconfigs[0][1]. > > ../arch/arm/kernel/setup.c: In function 'topology_init': > ../arch/arm/kernel/setup.c:977:3: error: implicit declaration of > function 'platform_can_hotplug_cpu' > [-Werror=implicit-function-declaration] > cc1: some warnings being treated as errors > make[2]: *** [arch/arm/kernel/setup.o] Error 1 > Ah right. asm/smp.h is not included unless CONFIG_SMP=y. We can move it into smp_plat.h. I'll wait to see if there any other comments before sending an update. ---8<--- diff --git a/arch/arm/include/asm/smp.h b/arch/arm/include/asm/smp.h index e15856a1a380..2563453d7b37 100644 --- a/arch/arm/include/asm/smp.h +++ b/arch/arm/include/asm/smp.h @@ -124,13 +124,4 @@ 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/include/asm/smp_plat.h b/arch/arm/include/asm/smp_plat.h index 0ad7d490ee6f..ebadc9956ffc 100644 --- a/arch/arm/include/asm/smp_plat.h +++ b/arch/arm/include/asm/smp_plat.h @@ -106,4 +106,13 @@ static inline u32 mpidr_hash_size(void) extern int platform_can_cpu_hotplug(void); +#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