Re: [PATCH 3/4] dma-buf: add support for mapping with dma mapping attributes

[Christoph Hellwig]

On Mon, Jan 21, 2019 at 12:20:42PM -0800, Liam Mark wrote:
> I have left this to clients, but if they own the buffer they can have the 
> knowledge as to whether CPU access is needed in that use case (example for 
> post-processing).

That is an API design which the user is more likely to get wrong than
right and thus does not pass the smell test.