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

Ira Weiny
2024-10-11T20:41:09Z

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
*/
struct dev_dax {
struct dax_region *region;