From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 52CFFEDE9A5 for ; Thu, 14 Sep 2023 11:05:26 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231404AbjINLF3 (ORCPT ); Thu, 14 Sep 2023 07:05:29 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:47226 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229485AbjINLF1 (ORCPT ); Thu, 14 Sep 2023 07:05:27 -0400 Received: from frasgout.his.huawei.com (frasgout.his.huawei.com [185.176.79.56]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 49AF21BF8; Thu, 14 Sep 2023 04:05:23 -0700 (PDT) Received: from lhrpeml500005.china.huawei.com (unknown [172.18.147.226]) by frasgout.his.huawei.com (SkyGuard) with ESMTP id 4RmZF36jdgz6HJdP; Thu, 14 Sep 2023 19:03:35 +0800 (CST) Received: from localhost (10.202.227.76) by lhrpeml500005.china.huawei.com (7.191.163.240) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2507.31; Thu, 14 Sep 2023 12:05:20 +0100 Date: Thu, 14 Sep 2023 12:05:19 +0100 From: Jonathan Cameron To: James Morse CC: , , , , , , , , , Salil Mehta , Russell King , Jean-Philippe Brucker , , Subject: Re: [RFC PATCH v2 03/35] drivers: base: Allow parts of GENERIC_CPU_DEVICES to be overridden Message-ID: <20230914120519.0000247e@Huawei.com> In-Reply-To: <20230913163823.7880-4-james.morse@arm.com> References: <20230913163823.7880-1-james.morse@arm.com> <20230913163823.7880-4-james.morse@arm.com> Organization: Huawei Technologies Research and Development (UK) Ltd. X-Mailer: Claws Mail 4.1.0 (GTK 3.24.33; x86_64-w64-mingw32) MIME-Version: 1.0 Content-Type: text/plain; charset="US-ASCII" Content-Transfer-Encoding: 7bit X-Originating-IP: [10.202.227.76] X-ClientProxiedBy: lhrpeml100004.china.huawei.com (7.191.162.219) To lhrpeml500005.china.huawei.com (7.191.163.240) X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: linux-arch@vger.kernel.org On Wed, 13 Sep 2023 16:37:51 +0000 James Morse wrote: > Architectures often have extra per-cpu work that needs doing > before a CPU is registered, often to determine if a CPU is > hotpluggable. > > To allow the ACPI architectures to use GENERIC_CPU_DEVICES, move > the cpu_register() call into arch_register_cpu(), which is made __weak > so architectures with extra work can override it. > This aligns with the way x86, ia64 and loongarch register hotplug CPUs > when they become present. Perhaps call out that you are also making cpu_devices visible outside of base/cpu.c Note it isn't obvious to me why you do that in this patch. I assume it will be needed later... Otherwise seems sensible to me. > > Signed-off-by: James Morse > --- > Changes since RFC: > * Dropped __init from x86/ia64 arch_register_cpu() > --- > arch/ia64/include/asm/cpu.h | 1 - > arch/ia64/kernel/topology.c | 2 +- > arch/loongarch/include/asm/cpu.h | 1 - > arch/x86/include/asm/cpu.h | 1 - > arch/x86/kernel/topology.c | 2 +- > drivers/base/cpu.c | 14 ++++++++++---- > include/linux/cpu.h | 5 +++++ > 7 files changed, 17 insertions(+), 9 deletions(-) > > diff --git a/arch/ia64/include/asm/cpu.h b/arch/ia64/include/asm/cpu.h > index db125df9e088..a3e690e685e5 100644 > --- a/arch/ia64/include/asm/cpu.h > +++ b/arch/ia64/include/asm/cpu.h > @@ -16,7 +16,6 @@ DECLARE_PER_CPU(struct ia64_cpu, cpu_devices); > DECLARE_PER_CPU(int, cpu_state); > > #ifdef CONFIG_HOTPLUG_CPU > -extern int arch_register_cpu(int num); > extern void arch_unregister_cpu(int); > #endif > > diff --git a/arch/ia64/kernel/topology.c b/arch/ia64/kernel/topology.c > index 94a848b06f15..741863a187a6 100644 > --- a/arch/ia64/kernel/topology.c > +++ b/arch/ia64/kernel/topology.c > @@ -59,7 +59,7 @@ void __ref arch_unregister_cpu(int num) > } > EXPORT_SYMBOL(arch_unregister_cpu); > #else > -static int __init arch_register_cpu(int num) > +int __init arch_register_cpu(int num) > { > return register_cpu(&sysfs_cpus[num].cpu, num); > } > diff --git a/arch/loongarch/include/asm/cpu.h b/arch/loongarch/include/asm/cpu.h > index 7afe8cbb844e..b8568e637420 100644 > --- a/arch/loongarch/include/asm/cpu.h > +++ b/arch/loongarch/include/asm/cpu.h > @@ -130,7 +130,6 @@ enum cpu_type_enum { > > #if !defined(__ASSEMBLY__) > #ifdef CONFIG_HOTPLUG_CPU > -int arch_register_cpu(int num); > void arch_unregister_cpu(int cpu); > #endif > #endif /* ! __ASSEMBLY__ */ > diff --git a/arch/x86/include/asm/cpu.h b/arch/x86/include/asm/cpu.h > index 3a233ebff712..96dc4665e87d 100644 > --- a/arch/x86/include/asm/cpu.h > +++ b/arch/x86/include/asm/cpu.h > @@ -28,7 +28,6 @@ struct x86_cpu { > }; > > #ifdef CONFIG_HOTPLUG_CPU > -extern int arch_register_cpu(int num); > extern void arch_unregister_cpu(int); > extern void soft_restart_cpu(void); > #endif > diff --git a/arch/x86/kernel/topology.c b/arch/x86/kernel/topology.c > index ca004e2e4469..0bab03130033 100644 > --- a/arch/x86/kernel/topology.c > +++ b/arch/x86/kernel/topology.c > @@ -54,7 +54,7 @@ void arch_unregister_cpu(int num) > EXPORT_SYMBOL(arch_unregister_cpu); > #else /* CONFIG_HOTPLUG_CPU */ > > -static int __init arch_register_cpu(int num) > +int __init arch_register_cpu(int num) > { > return register_cpu(&per_cpu(cpu_devices, num).cpu, num); > } > diff --git a/drivers/base/cpu.c b/drivers/base/cpu.c > index 34b48f660b6b..579064fda97b 100644 > --- a/drivers/base/cpu.c > +++ b/drivers/base/cpu.c > @@ -525,19 +525,25 @@ bool cpu_is_hotpluggable(unsigned int cpu) > EXPORT_SYMBOL_GPL(cpu_is_hotpluggable); > > #ifdef CONFIG_GENERIC_CPU_DEVICES > -static DEFINE_PER_CPU(struct cpu, cpu_devices); > +DEFINE_PER_CPU(struct cpu, cpu_devices); > + > +int __weak arch_register_cpu(int cpu) > +{ > + return register_cpu(&per_cpu(cpu_devices, cpu), cpu); > +} > #endif > > static void __init cpu_dev_register_generic(void) > { > -#ifdef CONFIG_GENERIC_CPU_DEVICES > int i; > > + if (!IS_ENABLED(CONFIG_GENERIC_CPU_DEVICES)) > + return; > + > for_each_present_cpu(i) { > - if (register_cpu(&per_cpu(cpu_devices, i), i)) > + if (arch_register_cpu(i)) > panic("Failed to register CPU device"); > } > -#endif > } > > #ifdef CONFIG_GENERIC_CPU_VULNERABILITIES > diff --git a/include/linux/cpu.h b/include/linux/cpu.h > index 0abd60a7987b..a71691d7c2ca 100644 > --- a/include/linux/cpu.h > +++ b/include/linux/cpu.h > @@ -80,12 +80,17 @@ extern __printf(4, 5) > struct device *cpu_device_create(struct device *parent, void *drvdata, > const struct attribute_group **groups, > const char *fmt, ...); > +extern int arch_register_cpu(int cpu); > #ifdef CONFIG_HOTPLUG_CPU > extern void unregister_cpu(struct cpu *cpu); > extern ssize_t arch_cpu_probe(const char *, size_t); > extern ssize_t arch_cpu_release(const char *, size_t); > #endif > > +#ifdef CONFIG_GENERIC_CPU_DEVICES > +DECLARE_PER_CPU(struct cpu, cpu_devices); > +#endif > + > /* > * These states are not related to the core CPU hotplug mechanism. They are > * used by various (sub)architectures to track internal state