On Mon, Sep 5, 2011 at 11:48 PM, canquan.shen <shencanquan@xxxxxxxxxx> wrote:
> On 2011/9/6 12:19, Bjorn Helgaas wrote:
>>>
>>> 主题: [PATCH] acpi: Fix hot cpu remove problem on acpi subsystem
>>>
>>> In Xen virtualization environment, When I used xen tools (xm vcpu-set
>>> vcpu_number ) to test the vcpu add and remove, I found it is failure on vcpu
>>> remove, I found the reason is that nothing to do when cpu remove in
>>> acpi_processor_hotplug_notify function, so I add the code of send the
>>> OFFLINE message to udev and add the rule of udev. it is ok on vcpu remove.
>>> Signed-off-by: Shen canquan<shencanquan@xxxxxxxxxx>
>>> ---
>>> drivers/acpi/processor_driver.c | 2 ++
>>> 1 files changed, 2 insertions(+), 0 deletions(-)
>>> diff --git a/drivers/acpi/processor_driver.c
>>> b/drivers/acpi/processor_driver.c
>>> index a4e0f1b..a1c564f 100644
>>> --- a/drivers/acpi/processor_driver.c
>>> +++ b/drivers/acpi/processor_driver.c
>>> @@ -677,6 +677,8 @@ static void acpi_processor_hotplug_notify(acpi_handle
>>> handle,
>>> "Driver data is NULL, dropping
>>> EJECT\n");
>>> return;
>>> }
>>> +
>>> + kobject_uevent(&device->dev.kobj, KOBJ_OFFLINE);
>>> break;
>>> default:
>>> ACPI_DEBUG_PRINT((ACPI_DB_INFO,
>>
>> The processor driver used to generate ONLINE and OFFLINE messages. I
>> removed them with c1815e0740. According to the changelog, the driver
>> core still generates KOBJ_ADD and KOBJ_REMOVE events.
>
> Thanks for your answer.
> When I used xen tools (xm vcpu-set vcpu_numer) to reduce the cpu number. I
> don't found any event . I use the following tool to capture the event:
> udevadm monitor --env --kernel --udev.
>
> If I used xen tools to add the cpu number , udev module will receive the
> KOBJ_ADD event.
>
> In my patch ,It is more fine to replace KOBJ_OFFLINE to KOBJ_REMOVE event .
I don't think we should emit KOBJ_REMOVE from the ACPI processor
driver. KOBJ_ADD is emitted by the driver model core
(device_register() -> device_add() path), and I think KOBJ_REMOVE
should also be emitted from the driver model core.
Is acpi_processor_remove() called when you remove a processor? I see
a path where it will be called via acpi_eject_store():
acpi_eject_store
acpi_os_hotplug_execute(acpi_bus_hot_remove_device)
acpi_bus_hot_remove_device
acpi_bus_trim
acpi_bus_remove
device_release_driver
dev->driver->remove (acpi_processor_remove())
acpi_device_unregister
device_unregister
device_del
kobject_uevent(KOBJ_REMOVE)
but as far as I can tell, this path is only used when we write
something to the "eject" sysfs file. I would think we'd want to use
most of this same path when we hot remove a CPU via the ACPI SCI
mechanism.
If you change acpi_processor_hotplug_notify() to use acpi_bus_trim()
for the removal case, you should get KOBJ_REMOVE events. Would that
be enough to make the xen vcpu remove work, or at least get you
closer?
> btw: how to find changelog of the c1815e0740.
git show c1815e0740
Bjorn
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