Re: [PATCH] can: Unify MTU settings for CAN interfaces

[Marc Kleine-Budde <mkl@pengutronix.de>]

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On 03/07/2014 09:23 AM, Oliver Hartkopp wrote:
> CAN interfaces only support MTU values of 16 (CAN 2.0) and 72 (CAN FD).
> Setting the MTU to other values is pointless but it does not really hurt.
> With the introduction of the CAN FD support in drivers/net/can a new
> function to switch the MTU for CAN FD has been introduced.
> 
> This patch makes use of this can_change_mtu() function to check for correct
> MTU settings also in legacy CAN (2.0) devices.
> 
> Signed-off-by: Oliver Hartkopp <socketcan@hartkopp.net>

> diff --git a/drivers/net/can/slcan.c b/drivers/net/can/slcan.c
> index 3fcdae2..f5b16e0 100644
> --- a/drivers/net/can/slcan.c
> +++ b/drivers/net/can/slcan.c
> @@ -411,10 +411,16 @@ static void slc_free_netdev(struct net_device *dev)
>  	slcan_devs[i] = NULL;
>  }
>  
> +static int slcan_change_mtu(struct net_device *dev, int new_mtu)
> +{
> +	return -EINVAL;
> +}
> +

Why is the slcan special?

>  static const struct net_device_ops slc_netdev_ops = {
>  	.ndo_open               = slc_open,
>  	.ndo_stop               = slc_close,
>  	.ndo_start_xmit         = slc_xmit,
> +	.ndo_change_mtu         = slcan_change_mtu,
>  };
>  
>  static void slc_setup(struct net_device *dev)

Marc

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