From: Evgeniy Polyakov <redacted>
Date: Wed, 9 Aug 2006 10:25:15 +0400

Unfortunately it is impossible to use list_empty(), since due to RCU
issues kevent can not use list_del_init(), so list_empty() will
always show that list is not empty.

I see, just use the LIST_POISON* scheme for now, it's something
we can refine later.