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

From: Eric Woudstra <[email-masked]>
Date: Sun, 13 Oct 2024 20:55:07 +0200

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 <[email-masked]>
---
 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)
+{
+#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))
+			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;
-- 
2.45.2