Linus Torvalds [off-list ref] wrote:

quoted

Add a wakeup call for a case whereby the caller already has the waitqueue
spinlock held.

That naming is crazy.

Sorry, yeah.  This is a bit hacked together at the moment and needs some more
tidying up.  I've had a lot of problems with performance regressions of up to
40% from seemingly simple changes involving moving locks around - it turns out
that the problem was that I was running with kasan enabled.

David