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 or SCI-initiated eject of memory devices fail e.g with: echo 1 >/sys/bus/pci/devices/PNP0C80:XX/eject 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. acpi_bus_remove() is 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. Note that unbinding the acpi driver from a memory device with: echo "PNP0C80:XX" > /sys/bus/acpi/drivers/acpi_memhotplug/unbind will no longer try to remove the memory. This is in compliance with normal unbind driver core semantics, see the discussion in v2 of this patchset: https://lkml.org/lkml/2012/11/16/649 After a successful unbind of the driver: - OSPM ejects of the memory device cannot proceed, as acpi_eject_store will return -ENODEV on missing driver. - SCI ejects of the memory device also cannot proceed, as they will also get a "driver data is NULL" error. So the memory can continue to be used safely after unbind. Patchset based on Rafael's linux-pm/linux-next (commit 78c38651). Comments welcome. v2->v3: - remove driver core changes. Only acpi core changes needed. Unbind semantics follow driver core rules. Unbind does not remove memory. - new patch to set enable bit in order to proceed with ejects on driver re-binding scenario. 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. Vasilis Liaskovitis (3): acpi: Introduce prepare_remove operation in acpi_device_ops acpi_memhotplug: Add prepare_remove operation acpi_memhotplug: Allow eject to proceed on rebind scenario drivers/acpi/acpi_memhotplug.c | 21 +++++++++++++++++---- drivers/acpi/scan.c | 9 ++++++++- include/acpi/acpi_bus.h | 2 ++ 3 files changed, 27 insertions(+), 5 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
