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Commit 2c22e652 authored by Rafael J. Wysocki's avatar Rafael J. Wysocki
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ACPI / scan: Use direct recurrence for device hierarchy walks 



Rework acpi_bus_trim() and acpi_bus_device_attach(), which is
renamed as acpi_bus_attach(), to walk the list of each device
object's children directly and call themselves recursively for
each child instead of using acpi_walk_namespace().  This
simplifies the code quite a bit and avoids the overhead of
callbacks and the ACPICA's internal processing which are not
really necessary for these two routines.

Signed-off-by: default avatarRafael J. Wysocki <rafael.j.wysocki@intel.com>
parent 25db115b

drivers/acpi/scan.c

+45 −75
Original line number Diff line number Diff line
@@ -1909,54 +1909,40 @@ static int acpi_scan_attach_handler(struct acpi_device *device) 
	return ret;

}



static acpi_status acpi_bus_device_attach(acpi_handle handle, u32 lvl_not_used,

					  void *not_used, void **ret_not_used)

static void acpi_bus_attach(struct acpi_device *device)

{

	struct acpi_device *device;

	unsigned long long sta;

	struct acpi_device *child;

	int ret;



	/*

	 * Ignore errors ignored by acpi_bus_check_add() to avoid terminating

	 * namespace walks prematurely.

	 */

	if (acpi_bus_type_and_status(handle, &ret, &sta))

		return AE_OK;



	if (acpi_bus_get_device(handle, &device))

		return AE_CTRL_DEPTH;



	acpi_set_device_status(device, sta);

	acpi_bus_get_status(device);

	/* Skip devices that are not present. */

	if (!acpi_device_is_present(device))

		goto err;



	if (!acpi_device_is_present(device)) {

		device->flags.visited = false;

		return;

	}

	if (device->handler)

		return AE_OK;

		goto ok;



	if (!device->flags.initialized) {

		acpi_bus_update_power(device, NULL);

		device->flags.initialized = true;

	}

	device->flags.visited = false;

	ret = acpi_scan_attach_handler(device);

	if (ret < 0)

		goto err;

		return;



	device->flags.match_driver = true;

	if (ret > 0)

		goto ok;



	if (!ret) {

		ret = device_attach(&device->dev);

		if (ret < 0)

		goto err;



 ok:

			return;

	}

	device->flags.visited = true;

	return AE_OK;



 err:

	device->flags.visited = false;

	return AE_CTRL_DEPTH;

 ok:

	list_for_each_entry(child, &device->children, node)

		acpi_bus_attach(child);

}



/**
@@ -1976,64 +1962,48 @@ static acpi_status acpi_bus_device_attach(acpi_handle handle, u32 lvl_not_used, 
int acpi_bus_scan(acpi_handle handle)

{

	void *device = NULL;

	int error = 0;



	if (ACPI_SUCCESS(acpi_bus_check_add(handle, 0, NULL, &device)))

		acpi_walk_namespace(ACPI_TYPE_ANY, handle, ACPI_UINT32_MAX,

				    acpi_bus_check_add, NULL, NULL, &device);



	if (!device)

		error = -ENODEV;

	else if (ACPI_SUCCESS(acpi_bus_device_attach(handle, 0, NULL, NULL)))

		acpi_walk_namespace(ACPI_TYPE_ANY, handle, ACPI_UINT32_MAX,

				    acpi_bus_device_attach, NULL, NULL, NULL);



	return error;

	if (device) {

		acpi_bus_attach(device);

		return 0;

	}

	return -ENODEV;

}

EXPORT_SYMBOL(acpi_bus_scan);



static acpi_status acpi_bus_device_detach(acpi_handle handle, u32 lvl_not_used,

					  void *not_used, void **ret_not_used)

/**

 * acpi_bus_trim - Detach scan handlers and drivers from ACPI device objects.

 * @adev: Root of the ACPI namespace scope to walk.

 *

 * Must be called under acpi_scan_lock.

 */

void acpi_bus_trim(struct acpi_device *adev)

{

	struct acpi_device *device = NULL;

	struct acpi_scan_handler *handler = adev->handler;

	struct acpi_device *child;



	if (!acpi_bus_get_device(handle, &device)) {

		struct acpi_scan_handler *dev_handler = device->handler;

	list_for_each_entry_reverse(child, &adev->children, node)

		acpi_bus_trim(child);



		if (dev_handler) {

			if (dev_handler->detach)

				dev_handler->detach(device);

	if (handler) {

		if (handler->detach)

			handler->detach(adev);



			device->handler = NULL;

		adev->handler = NULL;

	} else {

			device_release_driver(&device->dev);

		device_release_driver(&adev->dev);

	}

	/*

		 * Most likely, the device is going away, so put it into D3cold

		 * before that.

	 * Most likely, the device is going away, so put it into D3cold before

	 * that.

	 */

		acpi_device_set_power(device, ACPI_STATE_D3_COLD);

		device->flags.initialized = false;

		device->flags.visited = false;

	}

	return AE_OK;

}



/**

 * acpi_bus_trim - Remove ACPI device node and all of its descendants

 * @start: Root of the ACPI device nodes subtree to remove.

 *

 * Must be called under acpi_scan_lock.

 */

void acpi_bus_trim(struct acpi_device *start)

{

	/*

	 * Execute acpi_bus_device_detach() as a post-order callback to detach

	 * all ACPI drivers from the device nodes being removed.

	 */

	acpi_walk_namespace(ACPI_TYPE_ANY, start->handle, ACPI_UINT32_MAX, NULL,

			    acpi_bus_device_detach, NULL, NULL);

	acpi_bus_device_detach(start->handle, 0, NULL, NULL);

	acpi_device_set_power(adev, ACPI_STATE_D3_COLD);

	adev->flags.initialized = false;

	adev->flags.visited = false;

}

EXPORT_SYMBOL_GPL(acpi_bus_trim);