linux-kernel - Re: [PATCH] net: dsa: mv88e6xxx: avoid error message on remove from VLAN 0

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Date:   Fri, 31 May 2019 10:31:05 -0400
From:   Vivien Didelot <vivien.didelot@...il.com>
To:     Nikita Yushchenko <nikita.yoush@...entembedded.com>
Cc:     Andrew Lunn <andrew@...n.ch>,
        Florian Fainelli <f.fainelli@...il.com>,
        "David S. Miller" <davem@...emloft.net>,
        Heiner Kallweit <hkallweit1@...il.com>,
        Marek Behún <marek.behun@....cz>,
        Russell King <rmk+kernel@...linux.org.uk>,
        netdev@...r.kernel.org, linux-kernel@...r.kernel.org,
        Chris Healy <cphealy@...il.com>,
        Nikita Yushchenko <nikita.yoush@...entembedded.com>
Subject: Re: [PATCH] net: dsa: mv88e6xxx: avoid error message on remove from
 VLAN 0

Hi Nikita,

On Fri, 31 May 2019 10:35:14 +0300, Nikita Yushchenko <nikita.yoush@...entembedded.com> wrote:
> When non-bridged, non-vlan'ed mv88e6xxx port is moving down, error
> message is logged:
> 
> failed to kill vid 0081/0 for device eth_cu_1000_4
> 
> This is caused by call from __vlan_vid_del() with vin set to zero, over
> call chain this results into _mv88e6xxx_port_vlan_del() called with
> vid=0, and mv88e6xxx_vtu_get() called from there returns -EINVAL.
> 
> On symmetric path moving port up, call goes through
> mv88e6xxx_port_vlan_prepare() that calls mv88e6xxx_port_check_hw_vlan()
> that returns -EOPNOTSUPP for zero vid.
> 
> This patch changes mv88e6xxx_vtu_get() to also return -EOPNOTSUPP for
> zero vid, then this error code is explicitly cleared in
> dsa_slave_vlan_rx_kill_vid() and error message is no longer logged.
> 
> Signed-off-by: Nikita Yushchenko <nikita.yoush@...entembedded.com>
> ---
>  drivers/net/dsa/mv88e6xxx/chip.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/net/dsa/mv88e6xxx/chip.c b/drivers/net/dsa/mv88e6xxx/chip.c
> index 28414db979b0..6b77fde5f0e4 100644
> --- a/drivers/net/dsa/mv88e6xxx/chip.c
> +++ b/drivers/net/dsa/mv88e6xxx/chip.c
> @@ -1392,7 +1392,7 @@ static int mv88e6xxx_vtu_get(struct mv88e6xxx_chip *chip, u16 vid,
>  	int err;
>  
>  	if (!vid)
> -		return -EINVAL;
> +		return -EOPNOTSUPP;
>  
>  	entry->vid = vid - 1;
>  	entry->valid = false;

I'm not sure that I like the semantic of it, because the driver can actually
support VID 0 per-se, only the kernel does not use VLAN 0. Thus I would avoid
calling the port_vlan_del() ops for VID 0, directly into the upper DSA layer.

Florian, Andrew, wouldn't the following patch be more adequate?

    diff --git a/net/dsa/slave.c b/net/dsa/slave.c
    index 1e2ae9d59b88..80f228258a92 100644
    --- a/net/dsa/slave.c
    +++ b/net/dsa/slave.c
    @@ -1063,6 +1063,10 @@ static int dsa_slave_vlan_rx_kill_vid(struct net_device *dev, __be16 proto,
            struct bridge_vlan_info info;
            int ret;
     
    +       /* VID 0 has a special meaning and is never programmed in hardware */
    +       if (!vid)
    +               return 0;
    +
            /* Check for a possible bridge VLAN entry now since there is no
             * need to emulate the switchdev prepare + commit phase.
             */


Thanks,
Vivien