linux-kernel - Re: [PATCH net-next 4/4] net: dsa: Utilize __vlan_find_dev_deep

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Date:   Fri, 2 Oct 2020 08:42:20 +0000
From:   Vladimir Oltean <vladimir.oltean@....com>
To:     Florian Fainelli <f.fainelli@...il.com>
CC:     "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
        Andrew Lunn <andrew@...n.ch>,
        Vivien Didelot <vivien.didelot@...il.com>,
        "David S. Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>,
        open list <linux-kernel@...r.kernel.org>,
        "olteanv@...il.com" <olteanv@...il.com>
Subject: Re: [PATCH net-next 4/4] net: dsa: Utilize __vlan_find_dev_deep_rcu()

On Thu, Oct 01, 2020 at 07:42:15PM -0700, Florian Fainelli wrote:
> Now that we are guaranteed that dsa_untag_bridge_pvid() is called after
> eth_type_trans() we can utilize __vlan_find_dev_deep_rcu() which will
> take care of finding an 802.1Q upper on top of a bridge master.
> 
> A common use case, prior to 12a1526d067 ("net: dsa: untag the bridge
> pvid from rx skbs") was to configure a bridge 802.1Q upper like this:
> 
> ip link add name br0 type bridge vlan_filtering 0
> ip link add link br0 name br0.1 type vlan id 1
> 
> in order to pop the default_pvid VLAN tag.
> 
> With this change we restore that behavior while still allowing the DSA
> receive path to automatically pop the VLAN tag.
> 
> Signed-off-by: Florian Fainelli <f.fainelli@...il.com>
> ---

Reviewed-by: Vladimir Oltean <vladimir.oltean@....com>

>  net/dsa/dsa_priv.h | 11 +++--------
>  1 file changed, 3 insertions(+), 8 deletions(-)
> 
> diff --git a/net/dsa/dsa_priv.h b/net/dsa/dsa_priv.h
> index d6ce8c2a2590..12998bf04e55 100644
> --- a/net/dsa/dsa_priv.h
> +++ b/net/dsa/dsa_priv.h
> @@ -204,7 +204,6 @@ static inline struct sk_buff *dsa_untag_bridge_pvid(struct sk_buff *skb)
>  	struct net_device *br = dp->bridge_dev;
>  	struct net_device *dev = skb->dev;
>  	struct net_device *upper_dev;
> -	struct list_head *iter;
>  	u16 vid, pvid, proto;
>  	int err;
>  
> @@ -246,13 +245,9 @@ static inline struct sk_buff *dsa_untag_bridge_pvid(struct sk_buff *skb)
>  	 * supports because vlan_filtering is 0. In that case, we should
>  	 * definitely keep the tag, to make sure it keeps working.
>  	 */
> -	netdev_for_each_upper_dev_rcu(dev, upper_dev, iter) {
> -		if (!is_vlan_dev(upper_dev))
> -			continue;
> -
> -		if (vid == vlan_dev_vlan_id(upper_dev))
> -			return skb;
> -	}
> +	upper_dev = __vlan_find_dev_deep_rcu(br, htons(proto), vid);
> +	if (upper_dev)
> +		return skb;
>  
>  	__vlan_hwaccel_clear_tag(skb);
>  
> -- 
> 2.25.1
>