[PATCH v2 0/2] workqueue lockdep limitations/bugs

This addresses the first two issues.

The third problem is actually caught when the flush ever does
anything, but that might be rare depending on the circumstances,
so I still think it'd be nice to catch it somehow, but right now
I don't have the time to look into it.

johannes

v2:
 * move the acquire/release into flush_work() where it used to be
 * also re-add the acquire/release into flush_workqueue()