Re: [net-next PATCH] net: dsa: rtl8366: Properly clear member config

[Jakub Kicinski <kuba@kernel.org>]

On Sat,  5 Sep 2020 12:32:33 +0200 Linus Walleij wrote:
> When removing a port from a VLAN we are just erasing the
> member config for the VLAN, which is wrong: other ports
> can be using it.
> 
> Just mask off the port and only zero out the rest of the
> member config once ports using of the VLAN are removed
> from it.
> 
> Reported-by: Florian Fainelli <f.fainelli@gmail.com>
> Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

I see you labeled this for net-net, but it reads like a fix, is it not?

Fixes: d8652956cf37 ("net: dsa: realtek-smi: Add Realtek SMI driver")

Like commit 15ab7906cc92 ("net: dsa: rtl8366: Fix VLAN semantics") had?

> diff --git a/drivers/net/dsa/rtl8366.c b/drivers/net/dsa/rtl8366.c
> index 2dcde7a91721..bd3c947976ce 100644
> --- a/drivers/net/dsa/rtl8366.c
> +++ b/drivers/net/dsa/rtl8366.c
> @@ -471,13 +471,19 @@ int rtl8366_vlan_del(struct dsa_switch *ds, int port,
>  				return ret;
>  
>  			if (vid == vlanmc.vid) {
> -				/* clear VLAN member configurations */
> -				vlanmc.vid = 0;
> -				vlanmc.priority = 0;
> -				vlanmc.member = 0;
> -				vlanmc.untag = 0;
> -				vlanmc.fid = 0;
> -
> +				/* Remove this port from the VLAN */
> +				vlanmc.member &= ~BIT(port);
> +				vlanmc.untag &= ~BIT(port);
> +				/*
> +				 * If no ports are members of this VLAN
> +				 * anymore then clear the whole member
> +				 * config so it can be reused.
> +				 */
> +				if (!vlanmc.member && vlanmc.untag) {
> +					vlanmc.vid = 0;
> +					vlanmc.priority = 0;
> +					vlanmc.fid = 0;
> +				}
>  				ret = smi->ops->set_vlan_mc(smi, i, &vlanmc);
>  				if (ret) {
>  					dev_err(smi->dev,