[PATCH 0/2] wait: introduce WQ_FLAG_EXCLUSIVE_HEAD

[Oleg Nesterov <oleg@redhat.com>]

On 03/19, Oleg Nesterov wrote:
>
> OK, I'll try to test/cleanup/resend tomorrow.

Cough. Still un-tested, sorry. I will test it somehow and report,
but I'd like to send this for review right now.

Because I simply can't decide what the new flag should actually
do, so please ack/nack the semantics/naming at least.

Changes:

	1. I decided it would be better to change __wait_event()
	   to accept wait.flags right now. This looks better in
	   any case to me, and otherwise we need to introduce the
	   __wait_exclusive_enum.

	   The change looks trivial (both actually), please tell
	   me if you think it doesn't deserve a separate patch.

	2. I won't insist, but WQ_FLAG_EXCLUSIVE_HEAD can be used
	   without WQ_FLAG_EXCLUSIVE.

	   Unlikely this can be useful, but it looks more natural
	   this way. Otherwise we need to add another check to
	   ensure that WQ_FLAG_EXCLUSIVE_HEAD can't come alone.

	   However, perhaps this means the new flag needs another
	   name. I agree in advance with any.

Oleg.