Re: [PATCH kernel v8 09/31] powerpc/powernv: Do not set "read" flag if direction==DMA_NONE

From: David Gibson
Date: Wed Apr 15 2015 - 04:33:12 EST

On Fri, Apr 10, 2015 at 04:30:51PM +1000, Alexey Kardashevskiy wrote:
> Normally a bitmap from the iommu_table is used to track what TCE entry
> is in use. Since we are going to use iommu_table without its locks and
> do xchg() instead, it becomes essential not to put bits which are not
> implied in the direction flag.

It's not clear to me from this why lack of locking implies the need to
not put extra bits in.

> This adds iommu_direction_to_tce_perm() (its counterpart is there already)
> and uses it for powernv's pnv_tce_build().
> Signed-off-by: Alexey Kardashevskiy <aik@xxxxxxxxx>

I have no objection to the patch though, so

Reviewed-by: David Gibson <david@xxxxxxxxxxxxxxxxxxxxx>

David Gibson | I'll have my music baroque, and my code
david AT | minimalist, thank you. NOT _the_ _other_
| _way_ _around_!

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