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SubjectRe: [RFC PATCH v4] acpi: indicate to platform when hot remove returns busy
On Mon, Jul 3, 2017 at 4:26 PM, Lee, Chun-Yi <joeyli.kernel@gmail.com> wrote:
> In hotplug logic, it always indicates non-specific failure to
> platform through _OST when handing acpi hot-remove event failed. Then
> platform terminates the hot-remove process but it can not identify
> the reason.
>
> Base on current hot-remove code, there have two situations that it
> returns busy:
> - OSPM try to offline an individual device, but the device offline
> function returns busy.
> - When the ejection event is applied to an "not offlined yet" container.
> OSPM send kobject change event to userspace and returns busy.
>
> Both of them will returns -EBUSY to acpi device hotplug function then
> hotplug function indicates non-specific failure to platform just like
> any other error, e.g. -ENODEV or -EIO.
>
> The benefit to platform for identifying the OS busy state is that
> platform can be applied different approach to handle the busy but
> not just terminate the hot-remove process by unknown reason. For
> example, platform can wait for a while then triggers hot-remove
> again.
>
> This RFC patch adds one more parameter to the handler function of
> acpi generic hotplug event to give the function a chance to propose
> the return code of _OST. In this case, it sets ost return code to
> ACPI_OST_SC_DEVICE_BUSY when the acpi hot remove function returns
> -EBUSY.
>

Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>

> v4:
> Use switch-case statements to simplify code. (Andy Shevchenko, Rafael J. Wysocki)
>
> v3:
> Removed redundant 'else' in acpi_ost_status_code(). (Andy Shevchenko)
>
> v2:
> Do not overwrite ost code in acpi_generic_hotplug_event(). Move
> the "error code to ost code" logic to a help function. (Andy Shevchenko)
>
> Cc: "Rafael J. Wysocki" <rjw@rjwysocki.net>
> Cc: Len Brown <lenb@kernel.org>
> Cc: Andy Shevchenko <andy.shevchenko@gmail.com>
> Cc: Michal Hocko <mhocko@suse.cz>
> Signed-off-by: "Lee, Chun-Yi" <jlee@suse.com>
> ---
> drivers/acpi/scan.c | 18 +++++++++++++-----
> 1 file changed, 13 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/acpi/scan.c b/drivers/acpi/scan.c
> index d531629..ce88175 100644
> --- a/drivers/acpi/scan.c
> +++ b/drivers/acpi/scan.c
> @@ -404,10 +404,6 @@ void acpi_device_hotplug(struct acpi_device *adev, u32 src)
> error = dock_notify(adev, src);
> } else if (adev->flags.hotplug_notify) {
> error = acpi_generic_hotplug_event(adev, src);
> - if (error == -EPERM) {
> - ost_code = ACPI_OST_SC_EJECT_NOT_SUPPORTED;
> - goto err_out;
> - }
> } else {
> int (*notify)(struct acpi_device *, u32);
>
> @@ -423,8 +419,20 @@ void acpi_device_hotplug(struct acpi_device *adev, u32 src)
> else
> goto out;
> }
> - if (!error)
> + switch (error) {
> + case 0:
> ost_code = ACPI_OST_SC_SUCCESS;
> + break;
> + case -EPERM:
> + ost_code = ACPI_OST_SC_EJECT_NOT_SUPPORTED;
> + break;
> + case -EBUSY:
> + ost_code = ACPI_OST_SC_DEVICE_BUSY;
> + break;
> + default:
> + ost_code = ACPI_OST_SC_NON_SPECIFIC_FAILURE;
> + break;
> + }
>
> err_out:
> acpi_evaluate_ost(adev->handle, src, ost_code, NULL);
> --
> 2.10.2
>



--
With Best Regards,
Andy Shevchenko

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