Re: [PATCH v2] acpi : acpi_bus_trim() stops removing devices whenfailing to remove the device
From: Greg Kroah-Hartman
Date: Fri Oct 19 2012 - 13:59:36 EST
On Fri, Oct 19, 2012 at 06:29:52AM +0200, Rafael J. Wysocki wrote:
> On Thursday 11 of October 2012 19:12:28 Yasuaki Ishimatsu wrote:
> > acpi_bus_trim() stops removing devices, when acpi_bus_remove() return error
> > number. But acpi_bus_remove() cannot return error number correctly.
> > acpi_bus_remove() only return -EINVAL, when dev argument is NULL. Thus even if
> > device cannot be removed correctly, acpi_bus_trim() ignores and continues to
> > remove devices. acpi_bus_hot_remove_device() uses acpi_bus_trim() for removing
> > devices. Therefore acpi_bus_hot_remove_device() can send "_EJ0" to firmware,
> > even if the device is running on the system. In this case, the system cannot
> > work well.
> > Vasilis hit the bug at memory hotplug and reported it as follow:
> > https://lkml.org/lkml/2012/9/26/318
> > So acpi_bus_trim() should check whether device was removed or not correctly.
> > The patch adds error check into some functions to remove the device.
> > Applying the patch, acpi_bus_trim() stops removing devices when failing
> > to remove the device. But I think there is no impact with the
> > exceptionof CPU and Memory hotplug path. Because other device also fails
> > but the fail is an irregular case like device is NULL.
> > v1->v2
> > - add a rollback for reinstalling a notify handler.
> > Signed-off-by: Yasuaki Ishimatsu <isimatu.yasuaki@xxxxxxxxxxxxxx>
> Greg, do you think there may be any problems with the changes in dd.c?
Yes, I don't like it.
remove should always work, just like the exit call in a module. It
means that the core wants to remove the driver, so it is going to
happen, a driver can't refuse it.
Which brings me to the larger question, why would this solve anything?
If the kernel wants to unbind a device, why would we ever not want that
So, NAK on this patch, sorry. Fix up the ACPI core to handle this
properly, don't mess with the driver core here.
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