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Date:   Mon, 13 Jun 2022 09:10:58 +0200
From:   Marc Kleine-Budde <mkl@pengutronix.de>
To:     Dario Binacchi <dario.binacchi@amarulasolutions.com>
Cc:     linux-kernel@vger.kernel.org, michael@amarulasolutions.com,
        Amarula patchwork <linux-amarula@amarulasolutions.com>,
        Oliver Hartkopp <socketcan@hartkopp.net>,
        "David S. Miller" <davem@davemloft.net>,
        Eric Dumazet <edumazet@google.com>,
        Jakub Kicinski <kuba@kernel.org>,
        Paolo Abeni <pabeni@redhat.com>,
        Vincent Mailhol <mailhol.vincent@wanadoo.fr>,
        Wolfgang Grandegger <wg@grandegger.com>,
        linux-can@vger.kernel.org, netdev@vger.kernel.org
Subject: Re: [PATCH v3 05/13] can: netlink: dump bitrate 0 if
 can_priv::bittiming.bitrate is -1U
Message-ID: <20220613071058.h6bmy6emswh76q5s@pengutronix.de>
References: <20220612213927.3004444-1-dario.binacchi@amarulasolutions.com>
 <20220612213927.3004444-6-dario.binacchi@amarulasolutions.com>
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On 12.06.2022 23:39:19, Dario Binacchi wrote:
> Adding Netlink support to the slcan driver made it necessary to set the
> bitrate to a fake value (-1U) to prevent open_candev() from failing. In
> this case the command `ip --details -s -s link show' would print
> 4294967295 as the bitrate value. The patch change this value in 0.
>=20
> Suggested-by: Marc Kleine-Budde <mkl@pengutronix.de>
> Signed-off-by: Dario Binacchi <dario.binacchi@amarulasolutions.com>
> ---
>=20
> (no changes since v1)
>=20
>  drivers/net/can/dev/netlink.c | 12 +++++++++---
>  1 file changed, 9 insertions(+), 3 deletions(-)
>=20
> diff --git a/drivers/net/can/dev/netlink.c b/drivers/net/can/dev/netlink.c
> index 7633d98e3912..788a6752fcc7 100644
> --- a/drivers/net/can/dev/netlink.c
> +++ b/drivers/net/can/dev/netlink.c
> @@ -505,11 +505,16 @@ static int can_fill_info(struct sk_buff *skb, const=
 struct net_device *dev)
>  	struct can_ctrlmode cm =3D {.flags =3D priv->ctrlmode};
>  	struct can_berr_counter bec =3D { };
>  	enum can_state state =3D priv->state;
> +	__u32 bitrate =3D priv->bittiming.bitrate;
> +	int ret =3D 0;
> =20
>  	if (priv->do_get_state)
>  		priv->do_get_state(dev, &state);
> =20
> -	if ((priv->bittiming.bitrate &&

What about changing this line to:

        if ((priv->bittiming.bitrate && priv->bittiming.bitrate !=3D -1 &&

This would make the code a lot cleaner. Can you think of a nice macro
name for the -1?

0 could be CAN_BITRATE_UNCONFIGURED or _UNSET. For -1 I cannot find a
catchy name, something like CAN_BITRATE_CONFIGURED_UNKOWN or
SET_UNKNOWN.

The macros can be added to bittiming.h and be part of this patch. Ofq
course the above code (and slcan.c) would make use of the macros instead
of using 0 and -1.

Marc

--=20
Pengutronix e.K.                 | Marc Kleine-Budde           |
Embedded Linux                   | https://www.pengutronix.de  |
Vertretung West/Dortmund         | Phone: +49-231-2826-924     |
Amtsgericht Hildesheim, HRA 2686 | Fax:   +49-5121-206917-5555 |

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