netdev - Re: [PATCH] ravb: implement MTU change while device is up

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Date:   Wed, 8 May 2019 18:59:01 +0300
From:   Sergei Shtylyov <sergei.shtylyov@...entembedded.com>
To:     Ulrich Hecht <uli+renesas@...nd.eu>,
        linux-renesas-soc@...r.kernel.org
Cc:     netdev@...r.kernel.org, davem@...emloft.net, wsa@...-dreams.de,
        horms@...ge.net.au, magnus.damm@...il.com
Subject: Re: [PATCH] ravb: implement MTU change while device is up

Hello!

On 05/08/2019 06:21 PM, Ulrich Hecht wrote:

> Uses the same method as various other drivers: shut the device down,
> change the MTU, then bring it back up again.
> 
> Tested on Renesas D3 Draak board.
> 
> Signed-off-by: Ulrich Hecht <uli+renesas@...nd.eu>

   You should have CC'ed me (as an reviewer for the Renesas drivers).

> ---
>  drivers/net/ethernet/renesas/ravb_main.c | 11 +++++++----
>  1 file changed, 7 insertions(+), 4 deletions(-)

   What about sh_eth?

> 
> diff --git a/drivers/net/ethernet/renesas/ravb_main.c b/drivers/net/ethernet/renesas/ravb_main.c
> index ef8f089..02c247c 100644
> --- a/drivers/net/ethernet/renesas/ravb_main.c
> +++ b/drivers/net/ethernet/renesas/ravb_main.c
> @@ -1810,13 +1810,16 @@ static int ravb_do_ioctl(struct net_device *ndev, struct ifreq *req, int cmd)
>  
>  static int ravb_change_mtu(struct net_device *ndev, int new_mtu)
>  {
> -	if (netif_running(ndev))
> -		return -EBUSY;
> +	if (!netif_running(ndev)) {
> +		ndev->mtu = new_mtu;
> +		netdev_update_features(ndev);
> +		return 0;
> +	}
>  
> +	ravb_close(ndev);
>  	ndev->mtu = new_mtu;
> -	netdev_update_features(ndev);
>  
> -	return 0;
> +	return ravb_open(ndev);

   How about the code below instead?

	if (netif_running(ndev))
		ravb_close(ndev);

 	ndev->mtu = new_mtu;
	netdev_update_features(ndev);

	if (netif_running(ndev))
		return ravb_open(ndev);

	return 0;

[...]

MBR, Sergei