Add a selftest to verify bonding behavior when `lacp_active` is set to `off`.

The test checks the following:
- The passive LACP bond should not send LACPDUs before receiving a partner's
  LACPDU.
- The transmitted LACPDUs must not include the active flag.
- After transitioning to EXPIRED and DEFAULTED states, the passive side should
  still not initiate LACPDUs.

Signed-off-by: Hangbin Liu <liuhangbin@gmail.com>
---
 .../selftests/drivers/net/bonding/Makefile    |  3 +-
 .../drivers/net/bonding/bond_passive_lacp.sh  | 93 +++++++++++++++++++
 2 files changed, 95 insertions(+), 1 deletion(-)
 create mode 100755 tools/testing/selftests/drivers/net/bonding/bond_passive_lacp.sh

diff --git a/tools/testing/selftests/drivers/net/bonding/Makefile b/tools/testing/selftests/drivers/net/bonding/Makefile
index 2b10854e4b1e..44b98f17f8ff 100644
--- a/tools/testing/selftests/drivers/net/bonding/Makefile
+++ b/tools/testing/selftests/drivers/net/bonding/Makefile
@@ -10,7 +10,8 @@ TEST_PROGS := \
 	mode-2-recovery-updelay.sh \
 	bond_options.sh \
 	bond-eth-type-change.sh \
-	bond_macvlan_ipvlan.sh
+	bond_macvlan_ipvlan.sh \
+	bond_passive_lacp.sh
 
 TEST_FILES := \
 	lag_lib.sh \
diff --git a/tools/testing/selftests/drivers/net/bonding/bond_passive_lacp.sh b/tools/testing/selftests/drivers/net/bonding/bond_passive_lacp.sh
new file mode 100755
index 000000000000..017d96a319a3
--- /dev/null
+++ b/tools/testing/selftests/drivers/net/bonding/bond_passive_lacp.sh
@@ -0,0 +1,93 @@
+#!/bin/bash
+# SPDX-License-Identifier: GPL-2.0
+#
+# Test if a bond interface works with lacp_active=off.
+
+# shellcheck disable=SC2034
+REQUIRE_MZ=no
+NUM_NETIFS=0
+lib_dir=$(dirname "$0")
+# shellcheck disable=SC1091
+source "$lib_dir"/../../../net/forwarding/lib.sh
+
+check_port_state()
+{
+	local netns=$1
+	local port=$2
+	local state=$3
+
+	ip -n "${netns}" -d -j link show "$port" | \
+		jq -e ".[].linkinfo.info_slave_data.ad_actor_oper_port_state_str | index(\"${state}\") != null" > /dev/null
+}
+
+trap cleanup EXIT
+setup_ns c_ns s_ns
+defer cleanup_all_ns
+
+# shellcheck disable=SC2154
+ip -n "${c_ns}" link add eth0 type veth peer name eth0 netns "${s_ns}"
+ip -n "${c_ns}" link add eth1 type veth peer name eth1 netns "${s_ns}"
+ip -n "${s_ns}" link set eth0 up
+ip -n "${s_ns}" link set eth1 up
+ip -n "${c_ns}" link add bond0 type bond mode 802.3ad lacp_active off lacp_rate fast
+ip -n "${c_ns}" link set eth0 master bond0
+ip -n "${c_ns}" link set eth1 master bond0
+ip -n "${c_ns}" link set bond0 up
+
+# 1. The passive side shouldn't send LACPDU.
+RET=0
+client_mac=$(cmd_jq "ip -j -n ${c_ns} link show bond0" ".[].address")
+# Wait for the first LACPDU due to state change.
+sleep 2
+timeout 62 ip netns exec "${c_ns}" tcpdump --immediate-mode -c 1 -i eth0 \
+	-nn -l -vvv ether proto 0x8809 2> /dev/null > /tmp/client_init.out
+grep -q "System $client_mac" /tmp/client_init.out && RET=1
+log_test "802.3ad" "init port pkt lacp_active off"
+
+# 2. The passive side should not have the 'active' flag.
+RET=0
+check_port_state "${c_ns}" "eth0" "active" && RET=1
+log_test "802.3ad" "port state lacp_active off"
+
+# Set up the switch side with active mode.
+ip -n "${s_ns}" link set eth0 down
+ip -n "${s_ns}" link set eth1 down
+ip -n "${s_ns}" link add bond0 type bond mode 802.3ad lacp_active on lacp_rate fast
+ip -n "${s_ns}" link set eth0 master bond0
+ip -n "${s_ns}" link set eth1 master bond0
+ip -n "${s_ns}" link set bond0 up
+
+# 3. The active side should have the 'active' flag.
+RET=0
+check_port_state "${s_ns}" "eth0" "active" || RET=1
+log_test "802.3ad" "port state lacp_active on"
+
+# 4. Make sure the connection has not expired.
+RET=0
+slowwait 15 check_port_state "${s_ns}" "eth0" "expired" && RET=1
+slowwait 15 check_port_state "${s_ns}" "eth1" "expired" && RET=1
+log_test "bond 802.3ad" "port connect lacp_active off"
+
+# After testing, disconnect one port on each side to check the state.
+ip -n "${s_ns}" link set eth0 nomaster
+ip -n "${s_ns}" link set eth0 up
+ip -n "${c_ns}" link set eth1 nomaster
+ip -n "${c_ns}" link set eth1 up
+# 5. The passive side shouldn't send LACPDU anymore.
+RET=0
+# Wait for LACPDU due to state change.
+sleep 5
+timeout 62 ip netns exec "${c_ns}" tcpdump --immediate-mode -c 1 -i eth0 \
+	-nn -l -vvv ether proto 0x8809 2> /dev/null > /tmp/client_dis.out
+grep -q "System $client_mac" /tmp/client_dis.out && RET=1
+log_test "bond 802.3ad" "disconnect port pkt lacp_active off"
+
+# 6. The active side keeps sending LACPDU.
+RET=0
+switch_mac=$(cmd_jq "ip -j -n ${s_ns} link show bond0" ".[].address")
+timeout 62 ip netns exec "${s_ns}" tcpdump --immediate-mode -c 1 -i eth1 \
+	-nn -l -vvv ether proto 0x8809 2> /dev/null > /tmp/switch.out
+grep -q "System $switch_mac" /tmp/switch.out || RET=1
+log_test "bond 802.3ad" "disconnect port pkt lacp_active on"
+
+exit "$EXIT_STATUS"
-- 
2.46.0

On Fri, 25 Jul 2025 06:28:48 +0000 Hangbin Liu wrote:
> Add a selftest to verify bonding behavior when `lacp_active` is set to `off`.
> 
> The test checks the following:
> - The passive LACP bond should not send LACPDUs before receiving a partner's
>   LACPDU.
> - The transmitted LACPDUs must not include the active flag.
> - After transitioning to EXPIRED and DEFAULTED states, the passive side should
>   still not initiate LACPDUs.

Strangely this test fails on a normal kernel build but passes with
debug options enabled:

https://netdev.bots.linux.dev/contest.html?branch=net-next-2025-07-25--09-00&test=bond-passive-lacp-sh

On Fri, Jul 25, 2025 at 07:21:12AM -0700, Jakub Kicinski wrote:
> On Fri, 25 Jul 2025 06:28:48 +0000 Hangbin Liu wrote:
> > Add a selftest to verify bonding behavior when `lacp_active` is set to `off`.
> > 
> > The test checks the following:
> > - The passive LACP bond should not send LACPDUs before receiving a partner's
> >   LACPDU.
> > - The transmitted LACPDUs must not include the active flag.
> > - After transitioning to EXPIRED and DEFAULTED states, the passive side should
> >   still not initiate LACPDUs.
> 
> Strangely this test fails on a normal kernel build but passes with
> debug options enabled:
> 
> https://netdev.bots.linux.dev/contest.html?branch=net-next-2025-07-25--09-00&test=bond-passive-lacp-sh

I guess on the normal kernel, the checking starts too soon before negotiation
finished. I will add some sleep time before checking.

Thanks
Hangbin