On Tue, Sep 13, 2011 at 8:18 PM, canquan.shen <shencanquan@xxxxxxxxxx> wrote:
> We run linux as a guest in Xen environment. When we used the xen tools
> (xm vcpu-set <n>) to hot add and remove vcpu to and from the guest, we
> encountered the failure on vcpu removal. We found the reason is that it
> didn't go to really remove cpu in the cpu removal code path.
>
> This patch adds acpi_bus_trim in acpi_process_hotplug_notify to fix this
> issue. With this patch, it works fine for us.
>
> Signed-off-by: Shen canquan <shencanquan@xxxxxxxxxx>
> ---
> drivers/acpi/processor_driver.c | 7 +++++++
> 1 files changed, 7 insertions(+), 0 deletions(-)
>
> diff --git a/drivers/acpi/processor_driver.c
> b/drivers/acpi/processor_driver.c
> index a4e0f1b..0856ef8 100644
> --- a/drivers/acpi/processor_driver.c
> +++ b/drivers/acpi/processor_driver.c
> @@ -677,6 +677,13 @@ static void acpi_processor_hotplug_notify(acpi_handle
> handle,
> "Driver data is NULL, dropping EJECT\n");
> return;
> }
> + ACPI_DEBUG_PRINT((ACPI_DB_INFO,
> + "Hot-removing processor device %s\n",
> + dev_name(&device->dev)));
> + if (acpi_bus_trim(device, 1)) {
> + printk(KERN_ERR "ACPI: Removing device failed!\n");
We can do better than that. Nobody ever looks at ACPI_DEBUG_PRINT info.
u32 id;
...
id = pr->id;
if (acpi_bus_trim(device, 1))
printk(KERN_ERR PREFIX "Failed to remove CPU %d\n", id);
(No "return" needed here. In fact, the "return" at the bottom of
acpi_processor_hotplug_notify() is also superfluous. You could remove
it at the same time.)
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