Commit 
0794469da3f7b2093575cbdfc1108308dd3641ce: ("ACPI: struct device -
replace bus_id with dev_name(), dev_set_name()") introduced a bug by
testing 'dev_name(ldev)' instead of 'ldev->bus' for NULL when printing
out the bus information.
So if ldev->bus was NULL, we'd oops.
Reported-and-tested-by: Bruno Prémont <bonbons@linux-vserver.org>
Cc: Kay Sievers <kay.sievers@vrfy.org>
Cc: Len Brown <len.brown@intel.com>
Cc: Greg Kroah-Hartman <gregkh@suse.de>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
                           dev->wakeup.state.enabled ? "enabled" : "disabled");
                if (ldev)
                        seq_printf(seq, "%s:%s",
-                                  dev_name(ldev) ? ldev->bus->name : "no-bus",
+                                  ldev->bus ? ldev->bus->name : "no-bus",
                                   dev_name(ldev));
                seq_printf(seq, "\n");
                put_device(ldev);