Re: [PATCH v4] acpi: Fix CPU hot removal problem

[Bjorn Helgaas]

On Wed, Sep 14, 2011 at 7:06 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:Canquan Shen <shencanquan@xxxxxxxxxx>

Reviewed-by: Bjorn Helgaas <bhelgaas@xxxxxxxxxx>

> ---
>  drivers/acpi/processor_driver.c |    6 ++++++
>  1 files changed, 6 insertions(+), 0 deletions(-)
>
> diff --git a/drivers/acpi/processor_driver.c
> b/drivers/acpi/processor_driver.c
> index a4e0f1b..03d92d6 100644
> --- a/drivers/acpi/processor_driver.c
> +++ b/drivers/acpi/processor_driver.c
> @@ -641,6 +641,7 @@ static void acpi_processor_hotplug_notify(acpi_handle
> handle,
>        struct acpi_processor *pr;
>        struct acpi_device *device = NULL;
>        int result;
> +       u32 id;
>
>
>        switch (event) {
> @@ -677,6 +678,11 @@ static void acpi_processor_hotplug_notify(acpi_handle
> handle,
>                                    "Driver data is NULL, dropping EJECT\n");
>                        return;
>                }
> +               id = pr->id;
> +               if (acpi_bus_trim(device, 1)) {
> +                       printk(KERN_ERR  PREFIX
> +                                   "Fail to Remove CPU %d\n", id);
> +               }
>                break;
>        default:
>                ACPI_DEBUG_PRINT((ACPI_DB_INFO,
> --
> 1.7.6.0
>
>
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