lkml.org 
[lkml]   [2012]   [Nov]   [12]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [RFC PATCH 0/3] acpi: Introduce prepare_remove device operation
On Mon, Nov 12, 2012 at 12:00:55PM +0800, Wen Congyang wrote:
> At 11/09/2012 02:29 AM, Vasilis Liaskovitis Wrote:
> > As discussed in
> > https://patchwork.kernel.org/patch/1581581/
> > the driver core remove function needs to always succeed. This means we need
> > to know that the device can be successfully removed before acpi_bus_trim /
> > acpi_bus_hot_remove_device are called. This can cause panics when OSPM-initiated
> > eject (echo 1 > /sys/bus/acpi/devices/PNP/eject) of memory devices fails, since
> > the ACPI core goes ahead and ejects the device regardless of whether the memory
> > is still in use or not.
> >
> > For this reason a new acpi_device operation called prepare_remove is introduced.
> > This operation should be registered for acpi devices whose removal (from kernel
> > perspective) can fail. Memory devices fall in this category.
> >
> > acpi_bus_hot_remove_device is changed to handle removal in 2 steps:
> > - preparation for removal i.e. perform part of removal that can fail outside of
> > ACPI core. Should succeed for device and all its children.
> > - if above step was successfull, proceed to actual ACPI removal
>
> If we unbind the device from the driver, we still need to do preparation. But
> you don't do it in your patch.

yes, driver_unbind breaks with the current patchset. I 'll try to fix and
repost. However, I think this will require a new driver-core wide prepare_remove
callback (not only acpi-specific). I am not sure that would be acceptable.

thanks,

- Vasilis

>
> Thanks
> Wen Congyang
> >
> > acpi_bus_trim is changed accordingly to handle preparation for removal and
> > actual removal.
> >
> > With this patchset, only acpi memory devices use the new prepare_remove
> > device operation. The actual memory removal (VM-related offline and other memory
> > cleanups) is moved to prepare_remove. The old remove operation just cleans up
> > the acpi structures. Directly ejecting PNP0C80 memory devices works safely. I
> > haven't tested yet with an ACPI container which contains memory devices.
> >
> > Other ACPI devices (e.g. CPU) do not register prepare_remove callbacks, and
> > their OSPM-side eject should not be affected.
> >
> > I am not happy with the name prepare_remove. Comments welcome. Let me know if I
> > should work more in this direction (I think Yasuaki might also look into this
> > and might have a simpler idea)
> >
> > Patches are on top of Rafael's linux-pm/linux-next
> >
> > Vasilis Liaskovitis (3):
> > acpi: Introduce prepare_remove operation in acpi_device_ops
> > acpi: Make acpi_bus_trim handle device removal preparation
> > acpi_memhotplug: Add prepare_remove operation
> >
> > drivers/acpi/acpi_memhotplug.c | 24 +++++++++++++++++++++---
> > drivers/acpi/dock.c | 2 +-
> > drivers/acpi/scan.c | 32 +++++++++++++++++++++++++++++---
> > drivers/pci/hotplug/acpiphp_glue.c | 4 ++--
> > drivers/pci/hotplug/sgi_hotplug.c | 2 +-
> > include/acpi/acpi_bus.h | 4 +++-
> > 6 files changed, 57 insertions(+), 11 deletions(-)
> >
>


\
 
 \ /
  Last update: 2012-11-12 19:01    [W:0.075 / U:0.112 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site