Re: [PATCH v2 01/13] scatterlist: introduce sg_nents_for_dma() helper

From: Andy Shevchenko
Date: Mon Nov 10 2025 - 10:34:27 EST


On Mon, Nov 10, 2025 at 09:21:18AM -0600, Bjorn Andersson wrote:
> On Mon, Nov 10, 2025 at 09:05:26AM -0600, Bjorn Andersson wrote:
> > On Mon, Nov 10, 2025 at 11:23:28AM +0100, Andy Shevchenko wrote:

...

> > > int sg_nents(struct scatterlist *sg);
> > > int sg_nents_for_len(struct scatterlist *sg, u64 len);
> > > +int sg_nents_for_dma(struct scatterlist *sgl, unsigned int sglen, size_t len);


^^^

> > > +int sg_nents_for_dma(struct scatterlist *sgl, unsigned int sglen, size_t len)
>
> All but two clients store the value in an unsigned int. Changing the
> return type to unsigned int also signals that the function is just
> returning a count (no errors).

The type is chosen for the consistency with the existing APIs.
So, I prefer consistency in this case, if we need to change type, we need to do
that for all above APIs I believe. And this is out of the scope here.

Personally I was also puzzled of the choice as *nents members are all unsigned
int in the scatterlist.h.

...

> > We need an EXPORT_SYMBOL() here.

Good catch! I'll add it in next version.

> > With that, this looks good to me.
> >
> > Reviewed-by: Bjorn Andersson <andersson@xxxxxxxxxx>

Thanks!

--
With Best Regards,
Andy Shevchenko