linux-kernel - Re: [PATCH v3 5/5] acpi_processor: do not mark present at boot but not onlined CPU as onlined

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Message-ID: <20140414092147.GD19771@gmail.com>
Date:	Mon, 14 Apr 2014 11:21:47 +0200
From:	Ingo Molnar <mingo@...nel.org>
To:	Igor Mammedov <imammedo@...hat.com>
Cc:	linux-kernel@...r.kernel.org, tglx@...utronix.de, mingo@...hat.com,
	hpa@...or.com, x86@...nel.org, bp@...e.de,
	paul.gortmaker@...driver.com, JBeulich@...e.com, prarit@...hat.com,
	drjones@...hat.com, toshi.kani@...com, riel@...hat.com,
	gong.chen@...ux.intel.com, andi@...stfloor.org, lenb@...nel.org,
	rjw@...ysocki.net, linux-acpi@...r.kernel.org
Subject: Re: [PATCH v3 5/5] acpi_processor: do not mark present at boot but
 not onlined CPU as onlined


* Igor Mammedov <imammedo@...hat.com> wrote:

> acpi_processor_add() assumes that present at boot CPUs
> are always onlined, it is not so if a CPU failed to become
> onlined. As result acpi_processor_add() will mark such CPU
> device as onlined in sysfs and following attempts to
> online/offline it using /sys/device/system/cpu/cpuX/online
> attribute will fail.
> 
> Do not poke into device internals in acpi_processor_add()
> and touch "struct device { .offline }" attribute, since
> for CPUs onlined at boot it's set by:
>   topology_init() -> arch_register_cpu() -> register_cpu()
> before ACPI device tree is parsed, and for hotplugged
> CPUs it's set when userspace onlines CPU via sysfs.
> 
> Signed-off-by: Igor Mammedov <imammedo@...hat.com>
> ---
>  drivers/acpi/acpi_processor.c |    3 ---
>  1 files changed, 0 insertions(+), 3 deletions(-)

Can this fix be moved first too, or does it have undesirable side 
effects on unmodified kernels?

Thanks,

	Ingo
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