Commit d22ddcbc authored by Rafael J. Wysocki's avatar Rafael J. Wysocki
Browse files

ACPI / hotplug: Add demand_offline hotplug profile flag 



Add a new ACPI hotplug profile flag, demand_offline, such that if
set for the given ACPI device object's scan handler, it will cause
acpi_scan_hot_remove() to check if that device object's physical
companions are offline upfront and fail the hot removal if that
is not the case.

That flag will be useful to overcome a problem with containers on
some system where they can only be hot-removed after some cleanup
operations carried out by user space, which needs to be notified
of the container hot-removal before the kernel attempts to offline
devices in the container.  In those cases the current implementation
of acpi_scan_hot_remove() is not sufficient, because it first tries
to offline the devices in the container and only if that is
suffcessful it tries to offline the container itself.  As a result,
the container hot-removal notification is not delivered to user space
at the right time.

Signed-off-by: default avatarRafael J. Wysocki <rafael.j.wysocki@intel.com>
parent bfecc2b3

drivers/acpi/scan.c

+37 −4
Original line number Diff line number Diff line
@@ -126,6 +126,24 @@ acpi_device_modalias_show(struct device *dev, struct device_attribute *attr, cha 
}

static DEVICE_ATTR(modalias, 0444, acpi_device_modalias_show, NULL);



static bool acpi_scan_is_offline(struct acpi_device *adev)

{

	struct acpi_device_physical_node *pn;

	bool offline = true;



	mutex_lock(&adev->physical_node_lock);



	list_for_each_entry(pn, &adev->physical_node_list, node)

		if (device_supports_offline(pn->dev) && !pn->dev->offline) {

			kobject_uevent(&pn->dev->kobj, KOBJ_CHANGE);

			offline = false;

			break;

		}



	mutex_unlock(&adev->physical_node_lock);

	return offline;

}



static acpi_status acpi_bus_offline(acpi_handle handle, u32 lvl, void *data,

				    void **ret_p)

{
@@ -196,12 +214,11 @@ static acpi_status acpi_bus_online(acpi_handle handle, u32 lvl, void *data, 
	return AE_OK;

}



static int acpi_scan_hot_remove(struct acpi_device *device)

static int acpi_scan_try_to_offline(struct acpi_device *device)

{

	acpi_handle handle = device->handle;

	struct device *errdev;

	struct device *errdev = NULL;

	acpi_status status;

	unsigned long long sta;



	/*

	 * Carry out two passes here and ignore errors in the first pass,
@@ -212,7 +229,6 @@ static int acpi_scan_hot_remove(struct acpi_device *device) 
	 *

	 * If the first pass is successful, the second one isn't needed, though.

	 */

	errdev = NULL;

	status = acpi_walk_namespace(ACPI_TYPE_ANY, handle, ACPI_UINT32_MAX,

				     NULL, acpi_bus_offline, (void *)false,

				     (void **)&errdev);
@@ -241,6 +257,23 @@ static int acpi_scan_hot_remove(struct acpi_device *device) 
			return -EBUSY;

		}

	}

	return 0;

}



static int acpi_scan_hot_remove(struct acpi_device *device)

{

	acpi_handle handle = device->handle;

	unsigned long long sta;

	acpi_status status;



	if (device->handler->hotplug.demand_offline && !acpi_force_hot_remove) {

		if (!acpi_scan_is_offline(device))

			return -EBUSY;

	} else {

		int error = acpi_scan_try_to_offline(device);

		if (error)

			return error;

	}



	ACPI_DEBUG_PRINT((ACPI_DB_INFO,

		"Hot-removing device %s...\n", dev_name(&device->dev)));

include/acpi/acpi_bus.h

+2 −1
Original line number Diff line number Diff line
@@ -91,8 +91,9 @@ struct acpi_device; 


struct acpi_hotplug_profile {

	struct kobject kobj;

	bool enabled:1;

	int (*scan_dependent)(struct acpi_device *adev);

	bool enabled:1;

	bool demand_offline:1;

};



static inline struct acpi_hotplug_profile *to_acpi_hotplug_profile(

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