Re: [REPOST] RFC: sched: Prevent wakeup to enter critical section needlessly

[Andi Kleen]

> wait_event:
> 
> 	prepare_to_wait(wq)	// takes wq->lock
> 
> 	if (!CONDITION)
> 		schedule();
> 
> Now,
> 
> 	CONDITION = 1;
> 	wake_up(wq);
> 
> at least need the full mb() before lits_empty().

You're right, but it would probably only matter for inlining with LTO
(if the LTO compiler ever decides to do that)

Without that a call should be always enough barrier in practice.

So yes I would add the mb, but most likely it will not make much
difference. Just make sure to comment it.

-Andi
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