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SubjectRe: [PATCH v4 3/5] acpi_processor: do not mark present at boot but not onlined CPU as onlined
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On Mon, 2014-04-14 at 17:11 +0200, Igor Mammedov 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@redhat.com>
> ---
> v2:
> - fix regression in v1 leading to NULL pointer dereference
> on CPU unplug, do not remove "pr->dev = dev;"
> ---
> drivers/acpi/acpi_processor.c | 1 -
> 1 files changed, 0 insertions(+), 1 deletions(-)
>
> diff --git a/drivers/acpi/acpi_processor.c b/drivers/acpi/acpi_processor.c
> index c29c2c3..42d66f8 100644
> --- a/drivers/acpi/acpi_processor.c
> +++ b/drivers/acpi/acpi_processor.c
> @@ -404,7 +404,6 @@ static int acpi_processor_add(struct acpi_device *device,
> goto err;
>
> pr->dev = dev;
> - dev->offline = pr->flags.need_hotplug_init;

IIRC, this change was necessary to handle the case when maxcpus=X is
specified at boot. In this case, excessive CPU's dev->offline needs to
be set to 1. Can you verify this?

Thanks,
-Toshi



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