ACPI / PM: Prevent acpi_power_get_inferred_state() from making changes

acpi_power_get_inferred_state() should not update
device->power.state behind the back of its caller, so make it return
the state via a pointer instead.
Signed-off-by: NRafael J. Wysocki <rjw@sisk.pl>
Signed-off-by: NLen Brown <len.brown@intel.com>

drivers/acpi/bus.c

@@ -222,7 +222,8 @@ int acpi_bus_get_power(acpi_handle handle, int *state)
 		 * indirectly (via power resources).
 		 */
 		if (device->power.flags.power_resources) {
-			result = acpi_power_get_inferred_state(device);
+			result = acpi_power_get_inferred_state(device,
+							&device->power.state);
 			if (result)
 				return result;
 		} else if (device->power.flags.explicit_get) {

drivers/acpi/internal.h

@@ -41,7 +41,7 @@ static inline int acpi_debugfs_init(void) { return 0; }
 int acpi_power_init(void);
 int acpi_device_sleep_wake(struct acpi_device *dev,
                            int enable, int sleep_state, int dev_state);
-int acpi_power_get_inferred_state(struct acpi_device *device);
+int acpi_power_get_inferred_state(struct acpi_device *device, int *state);
 int acpi_power_transition(struct acpi_device *device, int state);
 extern int acpi_power_nocheck;
 

drivers/acpi/power.c

@@ -423,19 +423,16 @@ int acpi_disable_wakeup_device_power(struct acpi_device *dev)
                              Device Power Management
    -------------------------------------------------------------------------- */
 
-int acpi_power_get_inferred_state(struct acpi_device *device)
+int acpi_power_get_inferred_state(struct acpi_device *device, int *state)
 {
 	int result = 0;
 	struct acpi_handle_list *list = NULL;
 	int list_state = 0;
 	int i = 0;
 
-
-	if (!device)
+	if (!device || !state)
 		return -EINVAL;
 
-	device->power.state = ACPI_STATE_UNKNOWN;
-
 	/*
 	 * We know a device's inferred power state when all the resources
 	 * required for a given D-state are 'on'.
@@ -450,13 +447,12 @@ int acpi_power_get_inferred_state(struct acpi_device *device)
 			return result;
 
 		if (list_state == ACPI_POWER_RESOURCE_STATE_ON) {
-			device->power.state = i;
+			*state = i;
 			return 0;
 		}
 	}
 
-	device->power.state = ACPI_STATE_D3;
-
+	*state = ACPI_STATE_D3;
 	return 0;
 }