Re: [RFC][PATCH] atomic: Fix atomic_set_release() for 'funny' architectures

[Chris Metcalf]

On 6/9/2017 7:05 AM, Peter Zijlstra wrote:
> Subject: atomic: Fix atomic_set_release() for 'funny' architectures
>
> Those architectures that have a special atomic_set implementation also
> need a special atomic_set_release(), because for the very same reason
> WRITE_ONCE() is broken for them, smp_store_release() is too.
>
> The vast majority is architectures that have spinlock hash based atomic
> implementation except hexagon which seems to have a hardware 'feature'.
>
> The spinlock based atomics should be SC, that is, none of them appear to
> place extra barriers in atomic_cmpxchg() or any of the other SC atomic
> primitives and therefore seem to rely on their spinlock implementation
> being SC (I did not fully validate all that).
>
> Therefore, the normal atomic_set() is SC and can be used at
> atomic_set_release().

Acked-by: Chris Metcalf <cmetcalf@xxxxxxxxxxxx> [for tile]

--
Chris Metcalf, Mellanox Technologies
http://www.mellanox.com