OK, so 25-mm1 gave a lockdep error which made me look into this.

The first thing that I noticed was the horrible mess; the second thing I
saw was hacks like: 71e93d15

The problem is that arch idle routines are somewhat inconsitent with
their IRQ state handling and instead of fixing _that_, we go paper over
the problem.

So the thing I've tried to do is set a standard for idle routines and
fix them all up to adhere to that. So the rules are:

  idle routines are entered with IRQs disabled
  idle routines will exit with IRQs enabled

Nearly all already did this in one form or another.

Merge the 32 and 64 bit bits so they no longer have different bugs.

As for the actual lockdep warning; __sti_mwait() did a plainly un-annotated
irq-enable.
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Tested-by: Bob Copeland <me@bobcopeland.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>