Re: [RFC PATCH v3 2/3] acpi_memhotplug: Add prepare_remove operation
From: Wen Congyang <hidden>
Date: 2012-11-24 16:23:52
Also in:
linux-acpi, lkml
At 2012/11/24 1:50, Vasilis Liaskovitis Wrote:
Offlining and removal of memory is now done in the prepare_remove callback, not in the remove callback. The prepare_remove callback will be called when trying to remove a memory device with the following ways: 1. send eject request by SCI 2. echo 1>/sys/bus/pci/devices/PNP0C80:XX/eject 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
If we don't remove it when unbinding it, it may cause kernel panicked. I have explained in another mail. Thanks Wen Congyang
quoted hunk ↗ jump to hunk
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. Signed-off-by: Vasilis Liaskovitis<redacted> --- drivers/acpi/acpi_memhotplug.c | 18 ++++++++++++++++-- 1 files changed, 16 insertions(+), 2 deletions(-)diff --git a/drivers/acpi/acpi_memhotplug.c b/drivers/acpi/acpi_memhotplug.c index eb30e5a..d0cfbd9 100644 --- a/drivers/acpi/acpi_memhotplug.c +++ b/drivers/acpi/acpi_memhotplug.c@@ -55,6 +55,7 @@ MODULE_LICENSE("GPL"); static int acpi_memory_device_add(struct acpi_device *device); static int acpi_memory_device_remove(struct acpi_device *device, int type); +static int acpi_memory_device_prepare_remove(struct acpi_device *device); static const struct acpi_device_id memory_device_ids[] = { {ACPI_MEMORY_DEVICE_HID, 0},@@ -69,6 +70,7 @@ static struct acpi_driver acpi_memory_device_driver = { .ops = { .add = acpi_memory_device_add, .remove = acpi_memory_device_remove, + .prepare_remove = acpi_memory_device_prepare_remove, }, };@@ -448,6 +450,20 @@ static int acpi_memory_device_add(struct acpi_device *device) static int acpi_memory_device_remove(struct acpi_device *device, int type) { struct acpi_memory_device *mem_device = NULL; + + if (!device || !acpi_driver_data(device)) + return -EINVAL; + + mem_device = acpi_driver_data(device); + + acpi_memory_device_free(mem_device); + + return 0; +} + +static int acpi_memory_device_prepare_remove(struct acpi_device *device) +{ + struct acpi_memory_device *mem_device = NULL; int result; if (!device || !acpi_driver_data(device))@@ -459,8 +475,6 @@ static int acpi_memory_device_remove(struct acpi_device *device, int type) if (result) return result; - acpi_memory_device_free(mem_device); - return 0; }
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