Re: [PATCH v10 1/4] qrwlock: A queue read/write lock implementation

[Linus Torvalds]

On Thu, Jan 23, 2014 at 9:12 AM, Waiman Long <waiman.long@xxxxxx> wrote:
>
> I thought that all atomic RMW instructions are memory barrier.

On x86 they are. Not necessarily elsewhere.

> If they are not, what kind of barrier should be added?

smp_mb__before_atomic_xyz() and smp_mb__after_atomic_xyz() will do it,
and are no-op (well, barriers - I don't think it matters) on x86.

            Linus
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