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Message-ID: <CAMZ6RqJGjEMfst=4ksGeTnxovbALpSH4DX0fnajqKrO8Jivgag@mail.gmail.com> Date: Tue, 22 Aug 2023 01:50:04 +0900 From: Vincent Mailhol <vincent.mailhol@...il.com> To: Oliver Hartkopp <socketcan@...tkopp.net> Cc: Jakub Kicinski <kuba@...nel.org>, Martin Hundebøll <martin@...nix.com>, Wolfgang Grandegger <wg@...ndegger.com>, Marc Kleine-Budde <mkl@...gutronix.de>, "David S . Miller" <davem@...emloft.net>, Eric Dumazet <edumazet@...gle.com>, Paolo Abeni <pabeni@...hat.com>, Chandrasekar Ramakrishnan <rcsekar@...sung.com>, linux-can <linux-can@...r.kernel.org>, netdev <netdev@...r.kernel.org>, open list <linux-kernel@...r.kernel.org> Subject: Re: [PATCH 1/2] can: netlink: support setting hardware filters On Mon. 21 Aug. 2023 at 04:21, Oliver Hartkopp <socketcan@...tkopp.net> wrote: > On 19.08.23 15:29, Vincent Mailhol wrote: > > On Sat. 19 Aug. 2023 at 22:10, Vincent Mailhol > > <vincent.mailhol@...il.com> wrote: > >> On Sat. 19 Aug. 2023, 01:19, Jakub Kicinski <kuba@...nel.org> 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 wrote too fast. The EFF and RTR flags are contained in the canid_t, > > so the current struct can_filter is able to handle these two flags. > > But it remains true that the CAN-FD flags (FDF and BRS) are currently > > not handled. Not to mention that more flags will come with the > > upcoming CAN XL. > > You are right with FDF where we could use the former CAN_ERR_FLAG value > which is not needed for hw filter API. And what about the BRS flag? > But regarding CAN XL we could use the Standard 11 bit ID handling with > another flag inside the remaining 18 bits. Then, wouldn't you still need one more flag to indicate that this is a CAN XL filter? > The general concept of re-using the struct can_filter makes sense to me > as this follows the widely used pattern in the af_can.c core and CAN_RAW > sockets. > > Best regards, > Oliver > > > > >> 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
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