1 files changed, 22 insertions, 5 deletions

diff --git a/drivers/acpi/scan.c b/drivers/acpi/scan.c
index ff9f6226085d..3e009674f333 100644
--- a/drivers/acpi/scan.c
+++ b/drivers/acpi/scan.c
@@ -1336,9 +1336,25 @@ static int acpi_bus_scan(acpi_handle handle, struct acpi_bus_ops *ops,
 
         if (child)
                 *child = device;
-        return 0;
+
+        if (device)
+                return 0;
+        else
+                return -ENODEV;
 }
 
+/*
+ * acpi_bus_add and acpi_bus_start
+ *
+ * scan a given ACPI tree and (probably recently hot-plugged)
+ * create and add or starts found devices.
+ *
+ * If no devices were found -ENODEV is returned which does not
+ * mean that this is a real error, there just have been no suitable
+ * ACPI objects in the table trunk from which the kernel could create
+ * a device and add/start an appropriate driver.
+ */
+
 int
 acpi_bus_add(struct acpi_device **child,
              struct acpi_device *parent, acpi_handle handle, int type)
@@ -1348,8 +1364,7 @@ acpi_bus_add(struct acpi_device **child,
         memset(&ops, 0, sizeof(ops));
         ops.acpi_op_add = 1;
 
-        acpi_bus_scan(handle, &ops, child);
-        return 0;
+        return acpi_bus_scan(handle, &ops, child);
 }
 EXPORT_SYMBOL(acpi_bus_add);
 
@@ -1357,11 +1372,13 @@ int acpi_bus_start(struct acpi_device *device)
 {
         struct acpi_bus_ops ops;
 
+        if (!device)
+                return -EINVAL;
+
         memset(&ops, 0, sizeof(ops));
         ops.acpi_op_start = 1;
 
-        acpi_bus_scan(device->handle, &ops, NULL);
-        return 0;
+        return acpi_bus_scan(device->handle, &ops, NULL);
 }
 EXPORT_SYMBOL(acpi_bus_start);