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

From: Waiman Long
Date: Thu Jan 23 2014 - 12:48:11 EST

On 01/23/2014 12:15 PM, Linus Torvalds wrote:
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.


Thank for the info. I am less familiar with that kind of issues on other architecture. I will add a smp_mb__after_atomic_dec() & send out a new patch.

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