[PATCH net-next v4 5/6] net: bridge: Add a configurable default FDB learning limit

Johannes Nixdorf
2023-09-19T12:17:54Z

Add a Kconfig option to configure a default FDB learning limit system
wide, so a distributor building a special purpose kernel can limit all
created bridges by default.

The limit is only a soft default setting and overrideable on a per bridge
basis using netlink.

Signed-off-by: Johannes Nixdorf <jnixdorf-oss@avm.de>
---
net/bridge/Kconfig | 13 +++++++++++++
net/bridge/br_device.c | 2 ++
2 files changed, 15 insertions(+)

diff --git a/net/bridge/Kconfig b/net/bridge/Kconfig
index 3c8ded7d3e84..c0d9c08088c4 100644
--- a/net/bridge/Kconfig
+++ b/net/bridge/Kconfig
@@ -84,3 +84,16 @@ config BRIDGE_CFM
Say N to exclude this support and reduce the binary size.

If unsure, say N.
+
+config BRIDGE_DEFAULT_FDB_MAX_LEARNED
+ int "Default FDB learning limit"
+ default 0
+ depends on BRIDGE
+ help
+ Sets a default limit on the number of learned FDB entries on
+ new bridges. This limit can be overwritten via netlink on a
+ per bridge basis.
+
+ The default of 0 disables the limit.
+
+ If unsure, say 0.
diff --git a/net/bridge/br_device.c b/net/bridge/br_device.c
index 9a5ea06236bd..3214391c15a0 100644
--- a/net/bridge/br_device.c
+++ b/net/bridge/br_device.c
@@ -531,6 +531,8 @@ void br_dev_setup(struct net_device *dev)
br->bridge_ageing_time = br->ageing_time = BR_DEFAULT_AGEING_TIME;
dev->max_mtu = ETH_MAX_MTU;

+ br->fdb_max_learned = CONFIG_BRIDGE_DEFAULT_FDB_MAX_LEARNED;
+
br_netfilter_rtable_init(br);
br_stp_timer_init(br);
br_multicast_init(br);

--
2.42.0