build_patches: Add hack which fixes forwarding on a stacked bridge

Currently we are utilizing stacked bridges to keep configuration of DSA
devices as close as possible to swconfig devices. The lower bridge is
for configuration of the DSA hardware and is vlan-aware, while the upper
bridge is used to connect wireless interfaces to the client interface.

A packet arriving from the switch might have the offload_fwd_mark flag
set in the skb to prevent it from being sent to DSA ports, as this has
already been done in hardware.

However, this flag is not cleared before the skb is processed by the
upper bridge, which prevents it from being sent to any other ports of
that bridge. Therefore, communication is not possible between different
ports of that bridge, while communication with the bridge interface
itself is possible.

This issue affects both the layer3 and node variant, but due to the
layer 2 architecture of the node firmware, it is far more noticeable in
the node firmware, as it prevents ethernet clients from sending packets
to the gateway.

Work around this issue by clearing the offload_fwd_mark flag before
passing the skb up.

Fixes: #205

Signed-off-by: Fabian Bläse <>
Reviewed-by: Johannes Kimmel <>
This commit is contained in:
Fabian Bläse 2022-02-24 00:06:56 +01:00
parent 5b23824344
commit 330ed1b52d
1 changed files with 32 additions and 0 deletions

View File

@ -0,0 +1,32 @@
From f53b71d2907eeb0d80e79d99fa7b756b5e5bf32b Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Fabian=20Bl=C3=A4se?= <>
Date: Thu, 24 Feb 2022 00:04:47 +0100
Subject: [PATCH] Add hack which fixes forwarding on a stacked bridge
configuration using DSA
.../hack-5.4/999-fix-stacked-bridge-forwarding.patch | 12 ++++++++++++
1 file changed, 12 insertions(+)
create mode 100644 target/linux/generic/hack-5.4/999-fix-stacked-bridge-forwarding.patch
diff --git a/target/linux/generic/hack-5.4/999-fix-stacked-bridge-forwarding.patch b/target/linux/generic/hack-5.4/999-fix-stacked-bridge-forwarding.patch
new file mode 100644
index 0000000000..e1d4cb9cd5
--- /dev/null
+++ b/target/linux/generic/hack-5.4/999-fix-stacked-bridge-forwarding.patch
@@ -0,0 +1,12 @@
+--- a/net/bridge/br_input.c
++++ b/net/bridge/br_input.c
+@@ -52,6 +52,9 @@ static int br_pass_frame_up(struct sk_bu
+ return NET_RX_DROP;
+ }
++ /* remove offload flag, so upper bridges do not drop the packet */
++ br_switchdev_frame_unmark(skb);
+ indev = skb->dev;
+ skb->dev = brdev;
+ skb = br_handle_vlan(br, NULL, vg, skb);