Previously we checked the device_attach() return value only when
CONFIG_BUG=y.  That caused this warning in builds where CONFIG_BUG is not
set:
  drivers/pci/bus.c:237:6: warning: variable 'retval' set but not used [-Wunused-but-set-variable]
Check the return value of device_attach() always and clean up after
failure.
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
 
        dev->match_driver = true;
        retval = device_attach(&dev->dev);
-       WARN_ON(retval < 0);
+       if (retval < 0) {
+               dev_warn(&dev->dev, "device attach failed (%d)\n", retval);
+               pci_proc_detach_device(dev);
+               pci_remove_sysfs_dev_files(dev);
+               return;
+       }
 
        dev->is_added = 1;
 }