PCI: acpiphp: check whether _ADR evaluation succeeded

Check whether we evaluated _ADR successfully.  Previously we ignored
failure, so we would have used garbage data from the stack as the device
and function number.

We return AE_OK so that we ignore only this slot and continue looking
for other slots.

Found by Coverity (CID 113981).
Signed-off-by: NBjorn Helgaas <bhelgaas@google.com>

drivers/pci/hotplug/acpiphp_glue.c

@@ -132,6 +132,15 @@ register_slot(acpi_handle handle, u32 lvl, void *context, void **rv)
 	if (!acpi_pci_check_ejectable(pbus, handle) && !is_dock_device(handle))
 		return AE_OK;
 
+	status = acpi_evaluate_integer(handle, "_ADR", NULL, &adr);
+	if (ACPI_FAILURE(status)) {
+		warn("can't evaluate _ADR (%#x)\n", status);
+		return AE_OK;
+	}
+
+	device = (adr >> 16) & 0xffff;
+	function = adr & 0xffff;
+
 	pdev = pbus->self;
 	if (pdev && pci_is_pcie(pdev)) {
 		tmp = acpi_find_root_bridge_handle(pdev);
@@ -144,10 +153,6 @@ register_slot(acpi_handle handle, u32 lvl, void *context, void **rv)
 		}
 	}
 
-	acpi_evaluate_integer(handle, "_ADR", NULL, &adr);
-	device = (adr >> 16) & 0xffff;
-	function = adr & 0xffff;
-
 	newfunc = kzalloc(sizeof(struct acpiphp_func), GFP_KERNEL);
 	if (!newfunc)
 		return AE_NO_MEMORY;