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Subject[PATCH v4 3/5] acpi_processor: do not mark present at boot but not onlined CPU as onlined
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 <>
- 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;

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

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