On Fri 02-03-18 14:35:08, Lee, Chun-Yi wrote:
> In current design of ACPI container offline, Kernel emits
> KOBJ_CHANGE uevent to user space to indidate that the ejection of
> the container was triggered by platform. (caa73ea15 patch)
>
> A pure KOBJ_CHANGE uevent is not enough for user space to identify
> the purpose. For example, a "udevadm trigger" command can also
> be used to emit change event to all udev rules. A udev rule can not
> identify that the event is from kernel for offline or from udevadm
> for other purpose. Then the offline action in udev rule may also be
> triggered by udevadm tool.
>
> So, similar to the change uevent of dock, kernel sends the
> KOBJ_CHANGE uevent with a offline environmental data to indicate
> purpose. It's useful by udev rule for using ENV{EVENT} filter.
Looks reasonable to me. I have also tested this on Huawei Kunlun server
which hits the offline & online storm as a result of udevadm triggered
and a container udev rule which hooks into change event and offlines
all devices attached to the container. This patch allowed the udev rule
to be more targeted at the offline event.
> Cc: Michal Hocko <mhocko@xxxxxxxxxx>
> Cc: "Rafael J. Wysocki" <rjw@xxxxxxxxxxxxx>
> Cc: Len Brown <lenb@xxxxxxxxxx>
> Signed-off-by: "Lee, Chun-Yi" <jlee@xxxxxxxx>
Acked-by: Michal Hocko <mhocko@xxxxxxxx>
Tested-by: Michal Hocko <mhocko@xxxxxxxx>
> ---
> drivers/acpi/scan.c | 3 ++-
> 1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/acpi/scan.c b/drivers/acpi/scan.c
> index 8e63d93..f6dca9b 100644
> --- a/drivers/acpi/scan.c
> +++ b/drivers/acpi/scan.c
> @@ -116,6 +116,7 @@ bool acpi_scan_is_offline(struct acpi_device *adev, bool uevent)
> {
> struct acpi_device_physical_node *pn;
> bool offline = true;
> + static const char *envp[] = { "EVENT=offline", NULL };
>
> /*
> * acpi_container_offline() calls this for all of the container's
> @@ -126,7 +127,7 @@ bool acpi_scan_is_offline(struct acpi_device *adev, bool uevent)
> list_for_each_entry(pn, &adev->physical_node_list, node)
> if (device_supports_offline(pn->dev) && !pn->dev->offline) {
> if (uevent)
> - kobject_uevent(&pn->dev->kobj, KOBJ_CHANGE);
> + kobject_uevent_env(&pn->dev->kobj, KOBJ_CHANGE, envp);
>
> offline = false;
> break;
> --
> 2.10.2
--
Michal Hocko
SUSE Labs
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