Re: [RFC 00/17] DRM: fix struct sg_table nents vs. orig_nents misuse

Daniel Vetter
2020-04-28T15:32:11Z

On Tue, Apr 28, 2020 at 04:02:57PM +0200, Christoph Hellwig wrote:
> On Tue, Apr 28, 2020 at 03:19:48PM +0200, Marek Szyprowski wrote:
> > 1. introduce a dma_{map,sync,unmap}_sgtable() wrappers, which will use
> > a proper sg_table entries and call respective DMA-mapping functions
> > and adapt current code to it
>
> That sounds reasonable to me. Those could be pretty trivial wrappers.
>
> >
> >
> > 2. rename nents and orig_nents to nr_pages, nr_dmas to clearly state
> > which one refers to which part of the scatterlist; I'm open for
> > other names for those entries
>
> nr_cpu_ents and nr_dma_ents might be better names, but it still would be
> a whole lot of churn for little gain. I think just good wrappers like
> suggested above might be more helpful.

I guess long-term we could aim for both? I.e. roll out better wrappers
first, once that's soaked through the tree, rename the last offenders.

Personally I like nr_cpu_ents and nr_dma_ents, that's about as clear as it
gets.
-Daniel
--
Daniel Vetter
Software Engineer, Intel Corporation