Re: wake_up_process implied memory barrier clarification

From: Oleg Nesterov
Date: Mon Aug 31 2015 - 14:36:16 EST


On 08/31, Boqun Feng wrote:
>
> Fair enough, I went too far. How about just a single paragraph saying
> that:
>
> The wake_up(), wait_event() and their friends have proper barriers in
> them, but these implicity barriers are only for the correctness for
> sleep and wakeup. So don't rely on these barriers for things that are
> neither wait-conditons nor task states.
>
> Is that OK to you?

Ask Paul ;) but personally I agree.

To me, the only thing a user should know about wake_up/try_to_wake_up
and barriers is that you do not need another barrier between setting
condition and waking up.

Oleg.

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