Re: [PATCH v4 05/28] dax: Document dax dev range tuple

Jonathan Cameron
2024-10-16T15:48:30Z

On Fri, 11 Oct 2024 15:40:58 -0500
Ira Weiny <ira.weiny@intel.com> wrote:

> Jonathan Cameron wrote:
> > On Mon, 07 Oct 2024 18:16:11 -0500
> > Ira Weiny <ira.weiny@intel.com> wrote:
> >
> > > The device DAX structure is being enhanced to track additional DCD
> > > information.
> > >
> > > The current range tuple was not fully documented. Document it prior to
> > > adding information for DC.
> > >
> > > Suggested-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
> > > Signed-off-by: Ira Weiny <ira.weiny@intel.com>
> > >
> > Isn't this a nested struct?
> > https://docs.kernel.org/doc-guide/kernel-doc.html#nested-structs-unions
> >
> > I'm not quite sure how we document when it's a nested pointer to a
> > a structure. Is it the same as for a 'normal' nested struct?
>
> In this case I think it best to document the struct and just document the
> reference. See below.
>
> >
> > > ---
> > > Changes:
> > > [iweiny: move to start of series]
> > > ---
> > > drivers/dax/dax-private.h | 5 ++++-
> > > 1 file changed, 4 insertions(+), 1 deletion(-)
> > >
> > > diff --git a/drivers/dax/dax-private.h b/drivers/dax/dax-private.h
> > > index 446617b73aea..ccde98c3d4e2 100644
> > > --- a/drivers/dax/dax-private.h
> > > +++ b/drivers/dax/dax-private.h
> > > @@ -58,7 +58,10 @@ struct dax_mapping {
> > > * @dev - device core
> > > * @pgmap - pgmap for memmap setup / lifetime (driver owned)
> > > * @nr_range: size of @ranges
> > > - * @ranges: resource-span + pgoff tuples for the instance
> > > + * @ranges: range tuples of memory used
> > > + * @pgoff: page offset
> > @ranges.pgoff?
> > etc
>
> Ok yea.
>
> As for the pointer to a structure. I think the best thing to do is simply
> document that structure.
>
> Something like this building on this patch:
>
>
> diff --git a/drivers/dax/dax-private.h b/drivers/dax/dax-private.h
> index ccde98c3d4e2..b9816c933575 100644
> --- a/drivers/dax/dax-private.h
> +++ b/drivers/dax/dax-private.h
> @@ -40,6 +40,12 @@ struct dax_region {
> struct device *youngest;
> };
>
> +/**
> + * struct dax_mapping - device to display mapping range attributes
> + * @dev: device representing this range
> + * @range_id: index within dev_dax ranges array
> + * @id: ida of this mapping
> + */
> struct dax_mapping {
> struct device dev;
> int range_id;
> @@ -59,9 +65,9 @@ struct dax_mapping {
> * @pgmap - pgmap for memmap setup / lifetime (driver owned)
> * @nr_range: size of @ranges
> * @ranges: range tuples of memory used
> - * @pgoff: page offset
> - * @range: resource-span
> - * @mapping: device to assist in interrogating the range layout
> + * @ranges.pgoff: page offset
> + * @ranges.range: resource-span
> + * @ranges.mapping: reference to the dax_mapping for this range

Maybe just pull out definition of struct dev_dax_range?
Avoids this confusion and no particularly obvious reason why it
is embedded in the definition of dev_dax.

> */
> struct dev_dax {
> struct dax_region *region;
>