On Wed, Jul 06, 2016 at 11:17:10AM +0900, Byungchul Park wrote:
> 
> lock(A)
> wait_for(B)
> ~~~~~~~~~~~~~~~~~~~~~~~~ <- serialized by atomic operation
>               lock(A)
>               unlock(A)
>               wake(B)
> unlock(A)

By the way, I have a question. Is there anyone who could answer it?

I want to serialize between two context's lock operations, for example,

        context A       context B
        --------------  --------------
        lock A
        lock B          ...
        lock C
        atomic_inc_return
        ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ <- serialization
                        atomic_read
                        lock D
        ...             lock E
                        lock F

so that we can see these in the order like A -> B -> C -> D -> E -> F.

atomic_inc_return() is used after lock C in context A, and atomic_read()
is used before lock D in context B. And I want to make it serialized when
the atomic_read() can see the increased value.

Can I use smp_mb__after_atomic() just after atomic_read() or should I use
smp_mb()? I think anyway I have to choose one of them for that ordering.

Thank you,
Byungchul

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