[PATCH net v2 2/2] selftests: forwarding: bridge_mdb_max: add tests for mdb_n_entries warning

Nikolay Aleksandrov
2026-02-13T07:01:35Z

Recently we were able to trigger a warning in the mdb_n_entries counting
code. Add tests that exercise different ways which used to trigger that
warning.

Reviewed-by: Ido Schimmel <idosch@nvidia.com>
Signed-off-by: Nikolay Aleksandrov <nikolay@nvidia.com>
---
v2: fix 2 typos

.../net/forwarding/bridge_mdb_max.sh | 90 ++++++++++++++++++-
1 file changed, 88 insertions(+), 2 deletions(-)

diff --git a/tools/testing/selftests/net/forwarding/bridge_mdb_max.sh b/tools/testing/selftests/net/forwarding/bridge_mdb_max.sh
index 3da9d93ab36f..cf7a2d43a81a 100755
--- a/tools/testing/selftests/net/forwarding/bridge_mdb_max.sh
+++ b/tools/testing/selftests/net/forwarding/bridge_mdb_max.sh
@@ -28,6 +28,7 @@ ALL_TESTS="
test_8021d
test_8021q
test_8021qvs
+ test_mdb_count_warning
"

NUM_NETIFS=4
@@ -83,8 +84,6 @@ switch_create_8021q()
{
local br_flags=$1; shift

- log_info "802.1q $br_flags${br_flags:+ }tests"
-
ip link add name br0 type bridge vlan_filtering 1 vlan_default_pvid 0 \
mcast_snooping 1 $br_flags \
mcast_igmp_version 3 mcast_mld_version 2
@@ -106,6 +105,7 @@ switch_create_8021q()

switch_create_8021qvs()
{
+ log_info "802.1q mcast_vlan_snooping 1 tests"
switch_create_8021q "mcast_vlan_snooping 1"
bridge vlan global set dev br0 vid 10 mcast_igmp_version 3
bridge vlan global set dev br0 vid 10 mcast_mld_version 2
@@ -1272,6 +1272,76 @@ test_8021qvs_toggle_vlan_snooping()
test_toggle_vlan_snooping_permanent
}

+mdb_count_check_warn()
+{
+ local msg=$1; shift
+
+ dmesg | grep -q "WARNING:.*br_multicast_port_ngroups_dec.*"
+ check_fail $? "$msg"
+}
+
+test_mdb_count_mcast_vlan_snooping_flush()
+{
+ RET=0
+
+ # check if we already have a warning
+ mdb_count_check_warn "Check MDB entries count warning before test"
+
+ bridge mdb add dev br0 port "$swp1" grp 239.0.0.1 permanent vid 10
+ ip link set dev br0 down
+ ip link set dev br0 type bridge mcast_vlan_snooping 1
+ bridge mdb flush dev br0
+
+ mdb_count_check_warn "Check MDB entries count warning after test"
+
+ ip link set dev br0 type bridge mcast_vlan_snooping 0
+ ip link set dev br0 up
+
+ log_test "MDB count warning: mcast_vlan_snooping and MDB flush"
+}
+
+test_mdb_count_mcast_snooping_flush()
+{
+ RET=0
+
+ # check if we already have a warning
+ mdb_count_check_warn "Check MDB entries count warning before test"
+
+ bridge mdb add dev br0 port "$swp1" grp 239.0.0.1 permanent vid 10
+ ip link set dev br0 type bridge mcast_snooping 0
+ ip link set dev br0 type bridge mcast_vlan_snooping 1
+ bridge mdb flush dev br0
+
+ mdb_count_check_warn "Check MDB entries count warning after test"
+
+ ip link set dev br0 type bridge mcast_vlan_snooping 0
+ ip link set dev br0 type bridge mcast_snooping 1
+
+ log_test "MDB count warning: mcast_snooping and MDB flush"
+}
+
+test_mdb_count_vlan_state_flush()
+{
+ RET=0
+
+ # check if we already have a warning
+ mdb_count_check_warn "Check MDB entries count warning before test"
+
+ bridge mdb add dev br0 port "$swp1" grp 239.0.0.1 permanent vid 10
+ ip link set dev br0 down
+ bridge vlan set vid 10 dev "$swp1" state blocking
+ ip link set dev br0 type bridge mcast_vlan_snooping 1
+ ip link set dev br0 up
+ bridge mdb flush dev br0
+
+ mdb_count_check_warn "Check MDB entries count warning after test"
+
+ bridge vlan set vid 10 dev "$swp1" state forwarding
+ ip link set dev br0 type bridge mcast_vlan_snooping 0
+
+ log_test "MDB count warning: disabled vlan state and MDB flush"
+}
+
# test groups

test_8021d()
@@ -1297,6 +1367,7 @@ test_8021q()
{
# Tests for vlan_filtering 1 mcast_vlan_snooping 0.

+ log_info "802.1q tests"
switch_create_8021q
setup_wait

@@ -1334,6 +1405,21 @@ test_8021qvs()
switch_destroy
}

+test_mdb_count_warning()
+{
+ # Tests for mdb_n_entries warning
+
+ log_info "MDB count warning tests"
+ switch_create_8021q
+ setup_wait
+
+ test_mdb_count_mcast_vlan_snooping_flush
+ test_mdb_count_mcast_snooping_flush
+ test_mdb_count_vlan_state_flush
+
+ switch_destroy
+}
+
if ! bridge link help 2>&1 | grep -q "mcast_max_groups"; then
echo "SKIP: iproute2 too old, missing bridge \"mcast_max_groups\" support"
exit $ksft_skip
--
2.47.3