Re: [RFC PATCH v3] acpi: indicate to platform when hot remove returns busy

Rafael J. Wysocki
2017-06-28T22:20:52Z

On Wednesday, June 21, 2017 03:45:44 PM Lee, Chun-Yi 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.
>
> 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 | 21 +++++++++++++++------
> 1 file changed, 15 insertions(+), 6 deletions(-)
>
> diff --git a/drivers/acpi/scan.c b/drivers/acpi/scan.c
> index 3a10d7573477..41f5065190c7 100644
> --- a/drivers/acpi/scan.c
> +++ b/drivers/acpi/scan.c
> @@ -384,6 +384,20 @@ static int acpi_generic_hotplug_event(struct acpi_device *adev, u32 type)
> return -EINVAL;
> }
>
> +static int acpi_ost_status_code(u32 src, int error)
> +{
> + switch (src) {
> + case ACPI_NOTIFY_EJECT_REQUEST:
> + case ACPI_OST_EC_OSPM_EJECT:
> + if (error == -EPERM)
> + return ACPI_OST_SC_EJECT_NOT_SUPPORTED;
> + if (error == -EBUSY)
> + return ACPI_OST_SC_DEVICE_BUSY;
> + break;
> + }
> + return error ? ACPI_OST_SC_NON_SPECIFIC_FAILURE : ACPI_OST_SC_SUCCESS;
> +}

I'm not sure why you need the function above?

It only has one user anyway.

> +
> void acpi_device_hotplug(struct acpi_device *adev, u32 src)
> {
> u32 ost_code = ACPI_OST_SC_NON_SPECIFIC_FAILURE;
> @@ -404,10 +418,6 @@ 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);
>
> @@ -423,9 +433,8 @@ void acpi_device_hotplug(struct acpi_device *adev, u32 src)
> else
> goto out;
> }
> - if (!error)
> - ost_code = ACPI_OST_SC_SUCCESS;

I just would do:

switch (error) {
case 0:
ost_code = ACPI_OST_SC_SUCCESS;
break;
case -EBUSY:
ost_code = ACPI_OST_SC_DEVICE_BUSY;
break;
default:
ost_code = ACPI_OST_SC_NON_SPECIFIC_FAILURE;
break;
}

>
> + ost_code = acpi_ost_status_code(src, error);
> err_out:
> acpi_evaluate_ost(adev->handle, src, ost_code, NULL);
>
>

Thanks,
Rafael