On Thursday, November 15, 2012 11:22:47 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 or driver unbind of memory devices fails e.g with: > > echo 1 >/sys/bus/pci/devices/PNP0C80:XX/eject > echo "PNP0C80:XX" > /sys/bus/acpi/drivers/acpi_memhotplug/unbind > > since the ACPI core goes ahead and ejects the device regardless of whether the > 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. > A similar operation is introduced in bus_type to safely handle driver unbind > from the device driver core. > > acpi_bus_hot_remove_device and driver_unbind are changed to handle removal in 2 > steps: > - preparation for removal i.e. perform part of removal that can fail. Should > succeed for device and all its children. > - if above step was successfull, proceed to actual device 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. > > v1->v2: > - new patch to introduce bus_type prepare_remove callback. Needed to prepare > removal on driver unbinding from device-driver core. > - v1 patches 1 and 2 simplified and merged in one. acpi_bus_trim does not require > argument changes. > > Comments welcome. > > Vasilis Liaskovitis (3): > driver core: Introduce prepare_remove in bus_type > acpi: Introduce prepare_remove operation in acpi_device_ops > acpi_memhotplug: Add prepare_remove operation > > drivers/acpi/acpi_memhotplug.c | 22 ++++++++++++++++++++-- > drivers/acpi/scan.c | 21 ++++++++++++++++++++- > drivers/base/bus.c | 36 ++++++++++++++++++++++++++++++++++++ > include/acpi/acpi_bus.h | 2 ++ > include/linux/device.h | 2 ++ > 5 files changed, 80 insertions(+), 3 deletions(-) CCs of all driver core patches have to go to Greg Kroah-Hartman. Thanks, Rafael -- I speak only for myself. Rafael J. Wysocki, Intel Open Source Technology Center. -- To unsubscribe from this list: send the line "unsubscribe linux-acpi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
