Re: [PATCH v2 17/21] drivers: Remove explicit invocations of mmiowb()

[Linus Torvalds]

On Fri, Apr 5, 2019 at 4:01 AM Will Deacon <will.deacon@xxxxxxx> wrote:
>
> mmiowb() is now implied by spin_unlock() on architectures that require
> it, so there is no reason to call it from driver code. This patch was
> generated using coccinelle:
>
>         @mmiowb@
>         @@
>         - mmiowb();

So I love the patch series, and think we should just do it, but I do
wonder if some of the drivers involved end up relying on memory
ordering things (store_release -> load_aquire) and IO ordering rather
than using locking...

Wouldn't such use now be broken on ia64 SN platforms? Do we care?

So it might be worth noting that a lot of the mmiowb()s here weren't
paired with spin_unlock?

                    Linus