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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 Monday, April 14, 2014 05:11:15 PM 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;

    This line is to ensure that dev->offline and pr->flags.need_hotplug_init are
    consistent with each other. If you remove it, you need to ensure that they
    will be consistent in some other way.

    >
    > /* Trigger the processor driver's .probe() if present. */
    > if (device_attach(dev) >= 0)
    >

    --
    I speak only for myself.
    Rafael J. Wysocki, Intel Open Source Technology Center.


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