[RFC][PATCH] wake_up_var() memory ordering

Peter Zijlstra peterz at infradead.org
Tue Jun 25 06:27:36 PDT 2019


On Tue, Jun 25, 2019 at 02:12:22PM +0200, Andreas Gruenbacher wrote:

> > Only if we do as David suggested and make clean_and_wake_up_bit()
> > provide the RELEASE barrier.
> 
> (It's clear_and_wake_up_bit, not clean_and_wake_up_bit.)

Yes, typing hard.

> > That is, currently clear_and_wake_up_bit() is
> >
> >         clear_bit()
> >         smp_mb__after_atomic();
> >         wake_up_bit();
> >

> Now I'm confused because clear_and_wake_up_bit() in mainline does use
> clear_bit_unlock(), so it's the exact opposite of what you just said.

Argh; clearly I couldn't read. And then yes, you're right.



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