Subject: Re: [PATCH 0/3] virtio/vringh: kill off ACCESS_ONCE()

From: Mark Rutland <[email-masked]>
Date: Fri, 25 Nov 2016 18:07:03 +0000

On Fri, Nov 25, 2016 at 09:52:50AM -0800, Linus Torvalds wrote:
> READ/WRITE_ONCE() are atomic *WHEN*THAT*IS*POSSIBLE*.

> But sometimes it's not going to be atomic.

That's the problem.

Common code may rely on something being atomic when that's only true on
a subset of platforms. On others, it's silently "fixed" into something
that isn't atomic, and we get no diagnostic. The bug lurks beneath the
surface.

Thanks,
Mark.