[PATCH v2] ACPI / scan: Send the change uevent with offine environmental data

[PATCH v2] ACPI / scan: Send the change uevent with offine environmental data

[Lee, Chun-Yi]

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.

v2:
Fix build warning for the environmental string

Cc: "Rafael J. Wysocki" <rjw@rjwysocki.net>
Cc: Len Brown <lenb@kernel.org>
Acked-by: Michal Hocko <mhocko@suse.com>
Tested-by: Michal Hocko <mhocko@suse.com>
Signed-off-by: "Lee, Chun-Yi" <jlee@suse.com>
---
 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..490498e 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;
+	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

Re: [PATCH v2] ACPI / scan: Send the change uevent with offine environmental data

[Rafael J. Wysocki]

On Tuesday, March 20, 2018 6:51:26 AM CET 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.
> 
> v2:
> Fix build warning for the environmental string
> 
> Cc: "Rafael J. Wysocki" <rjw@rjwysocki.net>
> Cc: Len Brown <lenb@kernel.org>
> Acked-by: Michal Hocko <mhocko@suse.com>
> Tested-by: Michal Hocko <mhocko@suse.com>
> Signed-off-by: "Lee, Chun-Yi" <jlee@suse.com>
> ---
>  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..490498e 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;
> +	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;
> 

Applied, thanks!