Re: [PATCH 1/2] can: netlink: support setting hardware filters

[Vincent Mailhol]

On Sat. 19 Aug. 2023, 01:19, Jakub Kicinski <kuba@xxxxxxxxxx> wrote:
>
> On Thu, 17 Aug 2023 12:10:13 +0200 Martin Hundebøll wrote:
> > +             int len = nla_len(data[IFLA_CAN_HW_FILTER]);
> > +             int num_filter = len / sizeof(struct can_filter);
> > +             struct can_filter *filter = nla_data(data[IFLA_CAN_HW_FILTER]);
>
> This will prevent you from ever extending struct can_filter in
> a backward-compatible fashion, right? I obviously know very little
> about CAN but are you confident a more bespoke API to manipulate
> filters individually and allow extensibility is not warranted?

I follow Jakub's point of view.

The current struct can_filter is not sound. Some devices such as the
ES582.1 supports filtering of the CAN frame based on the flags (i.e.
SFF/EFF, RTR, FDF).

I think that each of the fields of the filter should have its own NLA
declaration with the whole thing wrapped within a NLA_NESTED_ARRAY.

I also think that there should then be a method to report the precise
filtering capabilities of the hardware.


Yours sincerely,
Vincent Mailhol