Re: [PATCH RFC v1 net-next 11/12] bridge: br_vlan_fill_forward_path_mode no _UNTAG_HW for dsa

[Nikolay Aleksandrov <razor@blackwall.org>]

On 13/10/2024 21:55, Eric Woudstra wrote:
> In network setup as below:
> 
>              fastpath bypass
>  .----------------------------------------.
> /                                          \
> |                        IP - forwarding    |
> |                       /                \  v
> |                      /                  wan ...
> |                     /
> |                     |
> |                     |
> |                   brlan.1
> |                     |
> |    +-------------------------------+
> |    |           vlan 1              |
> |    |                               |
> |    |     brlan (vlan-filtering)    |
> |    |               +---------------+
> |    |               |  DSA-SWITCH   |
> |    |    vlan 1     |               |
> |    |      to       |               |
> |    |   untagged    1     vlan 1    |
> |    +---------------+---------------+
> .         /                   \
>  ----->wlan1                 lan0
>        .                       .
>        .                       ^
>        ^                     vlan 1 tagged packets
>      untagged packets
> 
> Now that DEV_PATH_MTK_WDMA is added to nft_dev_path_info() the forward
> path is filled also when ending with the mediatek wlan1, info.indev not
> NULL now in nft_dev_forward_path(). This results in a direct transmit
> instead of a neighbor transmit. This is how it should be, But this fails.
> 
> br_vlan_fill_forward_path_mode() sets DEV_PATH_BR_VLAN_UNTAG_HW when
> filling in from brlan.1 towards wlan1. But it should be set to
> DEV_PATH_BR_VLAN_UNTAG in this case. Using BR_VLFLAG_ADDED_BY_SWITCHDEV
> is not correct. The dsa switchdev adds it as a foreign port.
> 
> Use BR_VLFLAG_TAGGING_BY_SWITCHDEV to make sure DEV_PATH_BR_VLAN_UNTAG is
> set when there is a dsa-switch inside the bridge.
> 
> Signed-off-by: Eric Woudstra <ericwouds@gmail.com>
> ---
>  net/bridge/br_private.h |  1 +
>  net/bridge/br_vlan.c    | 18 +++++++++++++++++-
>  2 files changed, 18 insertions(+), 1 deletion(-)
> 
> diff --git a/net/bridge/br_private.h b/net/bridge/br_private.h
> index 8da7798f9368..7d427214cc7c 100644
> --- a/net/bridge/br_private.h
> +++ b/net/bridge/br_private.h
> @@ -180,6 +180,7 @@ enum {
>  	BR_VLFLAG_MCAST_ENABLED = BIT(2),
>  	BR_VLFLAG_GLOBAL_MCAST_ENABLED = BIT(3),
>  	BR_VLFLAG_NEIGH_SUPPRESS_ENABLED = BIT(4),
> +	BR_VLFLAG_TAGGING_BY_SWITCHDEV = BIT(5),
>  };
>  
>  /**
> diff --git a/net/bridge/br_vlan.c b/net/bridge/br_vlan.c
> index 1830d7d617cd..b7877724b969 100644
> --- a/net/bridge/br_vlan.c
> +++ b/net/bridge/br_vlan.c
> @@ -3,6 +3,7 @@
>  #include <linux/netdevice.h>
>  #include <linux/rtnetlink.h>
>  #include <linux/slab.h>
> +#include <net/dsa.h>
>  #include <net/switchdev.h>
>  
>  #include "br_private.h"
> @@ -100,6 +101,19 @@ static void __vlan_flags_commit(struct net_bridge_vlan *v, u16 flags)
>  	__vlan_flags_update(v, flags, true);
>  }
>  
> +static inline bool br_vlan_tagging_by_switchdev(struct net_bridge *br)

no inline in .c files and also constify br

> +{
> +#if IS_ENABLED(CONFIG_NET_DSA)
> +	struct net_bridge_port *p;
> +
> +	list_for_each_entry(p, &br->port_list, list) {
> +		if (dsa_user_dev_check(p->dev))

I don't think this can change at runtime, so please keep a counter in
the bridge and don't walk the port list on every vlan add.

> +			return false;
> +	}
> +#endif
> +	return true;
> +}
> +
>  static int __vlan_vid_add(struct net_device *dev, struct net_bridge *br,
>  			  struct net_bridge_vlan *v, u16 flags,
>  			  struct netlink_ext_ack *extack)
> @@ -113,6 +127,8 @@ static int __vlan_vid_add(struct net_device *dev, struct net_bridge *br,
>  	if (err == -EOPNOTSUPP)
>  		return vlan_vid_add(dev, br->vlan_proto, v->vid);
>  	v->priv_flags |= BR_VLFLAG_ADDED_BY_SWITCHDEV;
> +	if (br_vlan_tagging_by_switchdev(br))
> +		v->priv_flags |= BR_VLFLAG_TAGGING_BY_SWITCHDEV;
>  	return err;
>  }
>  
> @@ -1491,7 +1507,7 @@ int br_vlan_fill_forward_path_mode(struct net_bridge *br,
>  
>  	if (path->bridge.vlan_mode == DEV_PATH_BR_VLAN_TAG)
>  		path->bridge.vlan_mode = DEV_PATH_BR_VLAN_KEEP;
> -	else if (v->priv_flags & BR_VLFLAG_ADDED_BY_SWITCHDEV)
> +	else if (v->priv_flags & BR_VLFLAG_TAGGING_BY_SWITCHDEV)
>  		path->bridge.vlan_mode = DEV_PATH_BR_VLAN_UNTAG_HW;
>  	else
>  		path->bridge.vlan_mode = DEV_PATH_BR_VLAN_UNTAG;