Revert "driver core: don't always lock parent in shutdown"

This reverts commit ba63537.

The series is being reverted before -rc1 as there are still reports of
lockups on shutdown, so it's not quite ready for "prime time."

Reported-by: Andrey Skvortsov <andrej.skvortzov@gmail.com>
Link: https://lore.kernel.org/r/ZvMkkhyJrohaajuk@skv.local
Cc: Christoph Hellwig <hch@lst.de>
Cc: David Jeffery <djeffery@redhat.com>
Cc: Keith Busch <kbusch@kernel.org>
Cc: Laurence Oberman <loberman@redhat.com>
Cc: Nathan Chancellor <nathan@kernel.org>
Cc: Sagi Grimberg <sagi@grimberg.me>
Cc: Stuart Hayes <stuart.w.hayes@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Author: gregkh

drivers/base/core.c

@@ -4816,7 +4816,7 @@ void device_shutdown(void)
 		spin_unlock(&devices_kset->list_lock);
 
 		/* hold lock to avoid race with probe/release */
-		if (parent && dev->bus && dev->bus->need_parent_lock)
+		if (parent)
 			device_lock(parent);
 		device_lock(dev);
 
@@ -4840,7 +4840,7 @@ void device_shutdown(void)
 		}
 
 		device_unlock(dev);
-		if (parent && dev->bus && dev->bus->need_parent_lock)
+		if (parent)
 			device_unlock(parent);
 
 		put_device(dev);