> >> Consider the following sequence of operations for a hotplugged memory
> >> device:
> >>
> >> 1. echo "PNP0C80:XX" > /sys/bus/acpi/drivers/acpi_memhotplug/unbind
> >> 2. echo 1 >/sys/bus/pci/devices/PNP0C80:XX/eject
> >>
> >> If we don't offline/remove the memory, we have no chance to do it in
> >> step 2. After
> >> step2, the memory is used by the kernel, but we have powered off it. It
> >> is very
> >> dangerous.
> >
> > How does power-off happen after unbind? acpi_eject_store checks for existing
> > driver before taking any action:
> >
> > #ifndef FORCE_EJECT
> > if (acpi_device->driver == NULL) {
> > ret = -ENODEV;
> > goto err;
> > }
> > #endif
> >
> > FORCE_EJECT is not defined afaict, so the function returns without scheduling
> > acpi_bus_hot_remove_device. Is there another code path that calls power-off?
>
> Consider the following case:
>
> We hotremove the memory device by SCI and unbind it from the driver at the same time:
>
> CPUa CPUb
> acpi_memory_device_notify()
> unbind it from the driver
> acpi_bus_hot_remove_device()
Can we make acpi_bus_remove() to fail if a given acpi_device is not
bound with a driver? If so, can we make the unbind operation to perform
unbind only?
Thanks,
-Toshi
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