Re: [PATCH v5 2/4] arch: Add lightweight memory barriers dma_rmb() and dma_wmb()

Will Deacon
2014-11-26T16:04:56Z

On Tue, Nov 25, 2014 at 04:26:28PM +0000, Alexander Duyck wrote:
> On 11/25/2014 06:01 AM, Will Deacon wrote:
> > If we ever see platforms using Linux/dma_alloc_coherent with devices
> > mastering from a different outer-shareable domain that the one containing
> > the CPUs, then we'll need to revisit this.
>
> Would we just need a system wide memory barrier in that case instead of
> an outer shareable memory barrier, or would we need to look as something
> like a sync barrier?

I think dmb(sy) would do the trick, but let's cross that bridge if/when we
have to.

Will