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(-) -- 1.7.9 -- 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
