There are currently no kernel tests that verify the effect of setting
the enabled team driver option. In a followup patch, there will be
changes to this option, so it will be important to make sure it still
behaves as it does now.

The test verifies that tcp continues to work across two different team
devices in separate network namespaces, even when member links are
manually disabled.

Signed-off-by: Marc Harvey <redacted>
---
Changes in v6:
- Use a tcp port with no associated service.
- Make tcpdump helper function not string-replace port numbers with
  associated service names, even on Fedora, which has a tcpdump patch
  that changes the required flag.
- Link to v5: https://lore.kernel.org/netdev/20260406-teaming-driver-internal-v5-4-e8a3f348a1c5@google.com/ (local)

Changes in v5:
- Use tcpdump for collecting traffic, rather than reading rx counters.
- Link to v4: https://lore.kernel.org/netdev/20260403-teaming-driver-internal-v4-4-d3032f33ca25@google.com/ (local)

Changes in v2:
- Fix shellcheck failures.
- Remove dependency on net forwarding lib and pipe viewer tools.
- Use iperf3 for tcp instead of netcat.
- Link to v1: https://lore.kernel.org/all/20260331053353.2504254-5-marcharvey@google.com/ (local)
---
 tools/testing/selftests/drivers/net/team/Makefile  |   2 +
 tools/testing/selftests/drivers/net/team/config    |   4 +
 .../testing/selftests/drivers/net/team/team_lib.sh | 148 +++++++++++++++++++
 .../drivers/net/team/transmit_failover.sh          | 158 +++++++++++++++++++++
 tools/testing/selftests/net/forwarding/lib.sh      |   9 +-
 5 files changed, 319 insertions(+), 2 deletions(-)

diff --git a/tools/testing/selftests/drivers/net/team/Makefile b/tools/testing/selftests/drivers/net/team/Makefile
index 02d6f51d5a06..777da2e0429e 100644
--- a/tools/testing/selftests/drivers/net/team/Makefile
+++ b/tools/testing/selftests/drivers/net/team/Makefile

@@ -7,9 +7,11 @@ TEST_PROGS := \
 	options.sh \
 	propagation.sh \
 	refleak.sh \
+	transmit_failover.sh \
 # end of TEST_PROGS
 
 TEST_INCLUDES := \
+	team_lib.sh \
 	../bonding/lag_lib.sh \
 	../../../net/forwarding/lib.sh \
 	../../../net/in_netns.sh \

diff --git a/tools/testing/selftests/drivers/net/team/config b/tools/testing/selftests/drivers/net/team/config
index 5d36a22ef080..8f04ae419c53 100644
--- a/tools/testing/selftests/drivers/net/team/config
+++ b/tools/testing/selftests/drivers/net/team/config

@@ -6,4 +6,8 @@ CONFIG_NETDEVSIM=m
 CONFIG_NET_IPGRE=y
 CONFIG_NET_TEAM=y
 CONFIG_NET_TEAM_MODE_ACTIVEBACKUP=y
+CONFIG_NET_TEAM_MODE_BROADCAST=y
 CONFIG_NET_TEAM_MODE_LOADBALANCE=y
+CONFIG_NET_TEAM_MODE_RANDOM=y
+CONFIG_NET_TEAM_MODE_ROUNDROBIN=y
+CONFIG_VETH=y

diff --git a/tools/testing/selftests/drivers/net/team/team_lib.sh b/tools/testing/selftests/drivers/net/team/team_lib.sh
new file mode 100644
index 000000000000..2057f5edee79
--- /dev/null
+++ b/tools/testing/selftests/drivers/net/team/team_lib.sh

@@ -0,0 +1,148 @@
+#!/bin/bash
+# SPDX-License-Identifier: GPL-2.0
+
+test_dir="$(dirname "$0")"
+export REQUIRE_MZ=no
+export NUM_NETIFS=0
+# shellcheck disable=SC1091
+source "${test_dir}/../../../net/forwarding/lib.sh"
+
+TCP_PORT="43434"
+
+# Create a team interface inside of a given network namespace with a given
+# mode, members, and IP address.
+# Arguments:
+#  namespace - Network namespace to put the team interface into.
+#  team - The name of the team interface to setup.
+#  mode - The team mode of the interface.
+#  ip_address - The IP address to assign to the team interface.
+#  prefix_length - The prefix length for the IP address subnet.
+#  $@ - members - The member interfaces of the aggregation.
+setup_team()
+{
+	local namespace=$1
+	local team=$2
+	local mode=$3
+	local ip_address=$4
+	local prefix_length=$5
+	shift 5
+	local members=("$@")
+
+	# Prerequisite: team must have no members
+	for member in "${members[@]}"; do
+		ip -n "${namespace}" link set "${member}" nomaster
+	done
+
+	# Prerequisite: team must have no address in order to set it
+	# shellcheck disable=SC2086
+	ip -n "${namespace}" addr del "${ip_address}/${prefix_length}" \
+			${NODAD} dev "${team}"
+
+	echo "Setting team in ${namespace} to mode ${mode}"
+
+	if ! ip -n "${namespace}" link set "${team}" down; then
+		echo "Failed to bring team device down"
+		return 1
+	fi
+	if ! ip netns exec "${namespace}" teamnl "${team}" setoption mode \
+			"${mode}"; then
+		echo "Failed to set ${team} mode to '${mode}'"
+		return 1
+	fi
+
+	# Aggregate the members into teams.
+	for member in "${members[@]}"; do
+		ip -n "${namespace}" link set "${member}" master "${team}"
+	done
+
+	# Bring team devices up and give them addresses.
+	if ! ip -n "${namespace}" link set "${team}" up; then
+		echo "Failed to set ${team} up"
+		return 1
+	fi
+
+	# shellcheck disable=SC2086
+	if ! ip -n "${namespace}" addr add "${ip_address}/${prefix_length}" \
+			${NODAD} dev "${team}"; then
+		echo "Failed to give ${team} IP address in ${namespace}"
+		return 1
+	fi
+}
+
+# This is global used to keep track of the sender's iperf3 process, so that it
+# can be terminated.
+declare sender_pid
+
+# Start sending and receiving TCP traffic with iperf3.
+# Globals:
+#  sender_pid - The process ID of the iperf3 sender process. Used to kill it
+#  later.
+start_listening_and_sending()
+{
+	ip netns exec "${NS2}" iperf3 -s -p "${TCP_PORT}" --logfile /dev/null &
+	# Wait for server to become reachable before starting client.
+	slowwait 5 ip netns exec "${NS1}" iperf3 -c "${NS2_IP}" -p \
+			"${TCP_PORT}" -t 1 --logfile /dev/null