Netlink specs, help dealing with nested array

Netlink specs, help dealing with nested array

[Kory Maincent]

Hello Jakub, Donald or other ynl experts,

I have an issue dealing with a nested array.

Here is my current netlink spec and ethtool patches:
https://termbin.com/gbyx
https://termbin.com/b325

Here is the error I got:
https://termbin.com/c7b1

I am trying to investigate what goes wrong with ynl but I still don't know.
If someone have an idea of what is going wrong with ynl or my specs it would be
lovely! 

Regards,
-- 
Köry Maincent, Bootlin
Embedded Linux and kernel engineering
https://bootlin.com

Re: Netlink specs, help dealing with nested array

[Donald Hunter]

On Fri, 21 Jun 2024 at 15:15, Kory Maincent <kory.maincent@bootlin.com> wrote:
>
> Hello Jakub, Donald or other ynl experts,
>
> I have an issue dealing with a nested array.
>
> Here is my current netlink spec and ethtool patches:
> https://termbin.com/gbyx

The yaml spec looks okay to me.

> https://termbin.com/b325

Have a look at ctrl_fill_info in net/netlink/genetlink.c for an
example nested array.

https://elixir.bootlin.com/linux/latest/source/net/netlink/genetlink.c#L1247

I think what you need is to move this outside the loop:

nla_nest_start(skb, ETHTOOL_A_C33_PSE_PW_LIMIT_RANGES);

and add nla_nest_start(skb, index) inside the loop.

> Here is the error I got:
> https://termbin.com/c7b1
>
> I am trying to investigate what goes wrong with ynl but I still don't know.
> If someone have an idea of what is going wrong with ynl or my specs it would be
> lovely!
>
> Regards,
> --
> Köry Maincent, Bootlin
> Embedded Linux and kernel engineering
> https://bootlin.com

Re: Netlink specs, help dealing with nested array

[Jakub Kicinski]

On Fri, 21 Jun 2024 16:15:43 +0200 Kory Maincent wrote:
> Hello Jakub, Donald or other ynl experts,
> 
> I have an issue dealing with a nested array.
> 
> Here is my current netlink spec and ethtool patches:
> https://termbin.com/gbyx
> https://termbin.com/b325
> 
> Here is the error I got:
> https://termbin.com/c7b1
> 
> I am trying to investigate what goes wrong with ynl but I still don't know.
> If someone have an idea of what is going wrong with ynl or my specs it would be
> lovely! 

You're (correctly) formatting your data as a basic multi-attr.
Instead of:

+        name: c33-pse-pw-limit-ranges
+        name-prefix: ethtool-a-
+        type: indexed-array
+        sub-type: nest
+        nested-attributes: c33-pse-pw-limit

use:

+        name: c33-pse-pw-limit-ranges
+        name-prefix: ethtool-a-
+        type: nest
+        multi-attr: true
+        nested-attributes: c33-pse-pw-limit

The indexed array is described here:
https://docs.kernel.org/next/userspace-api/netlink/genetlink-legacy.html#indexed-array
it has an extra layer of nesting, which uses the index in the array 
as the type of the attribute.

Re: Netlink specs, help dealing with nested array

[Donald Hunter]

On Fri, 21 Jun 2024 at 16:19, Jakub Kicinski <kuba@kernel.org> wrote:
>
> On Fri, 21 Jun 2024 16:15:43 +0200 Kory Maincent wrote:
> > Hello Jakub, Donald or other ynl experts,
> >
> > I have an issue dealing with a nested array.
> >
> > Here is my current netlink spec and ethtool patches:
> > https://termbin.com/gbyx
> > https://termbin.com/b325
> >
> > Here is the error I got:
> > https://termbin.com/c7b1
> >
> > I am trying to investigate what goes wrong with ynl but I still don't know.
> > If someone have an idea of what is going wrong with ynl or my specs it would be
> > lovely!
>
> You're (correctly) formatting your data as a basic multi-attr.
> Instead of:
>
> +        name: c33-pse-pw-limit-ranges
> +        name-prefix: ethtool-a-
> +        type: indexed-array
> +        sub-type: nest
> +        nested-attributes: c33-pse-pw-limit
>
> use:
>
> +        name: c33-pse-pw-limit-ranges
> +        name-prefix: ethtool-a-
> +        type: nest
> +        multi-attr: true
> +        nested-attributes: c33-pse-pw-limit

Ah yes, I was "fixing" things in the wrong direction. Sorry for the confusion.

Re: Netlink specs, help dealing with nested array

[Kory Maincent]

On Fri, 21 Jun 2024 16:27:57 +0100
Donald Hunter <donald.hunter@gmail.com> wrote:

> On Fri, 21 Jun 2024 at 16:19, Jakub Kicinski <kuba@kernel.org> wrote:
>  [...]  
>  [...]  
> >
> > You're (correctly) formatting your data as a basic multi-attr.
> > Instead of:
> >
> > +        name: c33-pse-pw-limit-ranges
> > +        name-prefix: ethtool-a-
> > +        type: indexed-array
> > +        sub-type: nest
> > +        nested-attributes: c33-pse-pw-limit
> >
> > use:
> >
> > +        name: c33-pse-pw-limit-ranges
> > +        name-prefix: ethtool-a-
> > +        type: nest
> > +        multi-attr: true
> > +        nested-attributes: c33-pse-pw-limit  
> 
> Ah yes, I was "fixing" things in the wrong direction. Sorry for the confusion.

Thanks Donald and Jakub!
It is working better with the right netlink specs.

Regards,
-- 
Köry Maincent, Bootlin
Embedded Linux and kernel engineering
https://bootlin.com