[PATCH net-next v3 4/4] selftests: net: Add protodown tests

[Ido Schimmel <idosch@nvidia.com>]

Add a selftest for the protodown mechanism.

Five test cases are included:

1. Basic protodown toggling: Verify that setting protodown on macvlan
   results in DOWN operational state and clearing it restores UP.

2. Same as the previous test case, but with vxlan.

3. Protodown reasons: Verify that protodown cannot be cleared while
   there are active protodown reasons, but can be cleared once all
   reasons are removed.

4. Protodown with lower device being toggled: Verify that toggling the
   lower device's carrier while protodown is on does not cause the
   macvlan to gain carrier.

5. Protodown with lower device down: Verify that toggling protodown
   while the lower device has no carrier does not cause the macvlan to
   gain carrier.

Note that the last two test cases fail without "net: Do not turn on
carrier when protodown is on" and "net: Do not unconditionally turn on
carrier when turning off protodown":

 # ./protodown.sh
 TEST: Basic protodown on/off with macvlan                           [ OK ]
 TEST: Basic protodown on/off with vxlan                             [ OK ]
 TEST: Protodown reasons                                             [ OK ]
 TEST: Protodown with lower device toggled                           [FAIL]
         Macvlan operational state is not DOWN despite protodown
 TEST: Protodown with lower device down                              [FAIL]
         Macvlan is not LOWERLAYERDOWN after clearing protodown

Assisted-by: Claude:claude-opus-4-6
Signed-off-by: Ido Schimmel <idosch@nvidia.com>
---
 tools/testing/selftests/net/Makefile     |   1 +
 tools/testing/selftests/net/protodown.sh | 182 +++++++++++++++++++++++
 2 files changed, 183 insertions(+)
 create mode 100755 tools/testing/selftests/net/protodown.sh

diff --git a/tools/testing/selftests/net/Makefile b/tools/testing/selftests/net/Makefile
index 88c7573a8295..ff1d58625589 100644
--- a/tools/testing/selftests/net/Makefile
+++ b/tools/testing/selftests/net/Makefile
@@ -69,6 +69,7 @@ TEST_PROGS := \
 	nl_netdev.py \
 	nl_nlctrl.py \
 	pmtu.sh \
+	protodown.sh \
 	psock_snd.sh \
 	reuseaddr_ports_exhausted.sh \
 	reuseport_addr_any.sh \
diff --git a/tools/testing/selftests/net/protodown.sh b/tools/testing/selftests/net/protodown.sh
new file mode 100755
index 000000000000..0a7b78c63c37
--- /dev/null
+++ b/tools/testing/selftests/net/protodown.sh
@@ -0,0 +1,182 @@
+#!/bin/bash
+# SPDX-License-Identifier: GPL-2.0
+#
+# Test the protodown mechanism. Verify basic protodown toggling, protodown
+# reasons, operational state when the lower device carrier changes, and correct
+# operational state when the lower device has no carrier.
+
+# shellcheck disable=SC1091,SC2034,SC2154,SC2317
+source lib.sh
+
+require_command jq
+
+ALL_TESTS="
+	protodown_basic_macvlan
+	protodown_basic_vxlan
+	protodown_reasons
+	protodown_lower_toggle
+	protodown_lower_down
+"
+
+operstate_get()
+{
+	local ns=$1; shift
+	local dev=$1; shift
+
+	ip -n "$ns" -j link show dev "$dev" | jq -r '.[].operstate'
+}
+
+operstate_check()
+{
+	local ns=$1; shift
+	local dev=$1; shift
+	local expected=$1; shift
+
+	local current
+	current=$(operstate_get "$ns" "$dev")
+
+	[ "$current" = "$expected" ]
+}
+
+setup_prepare()
+{
+	setup_ns NS
+	defer cleanup_all_ns
+
+	ip -n "$NS" link add name dummy0 up type dummy
+
+	ip -n "$NS" link add name macvlan0 link dummy0 up type macvlan mode bridge
+
+	ip -n "$NS" link add name vxlan0 up type vxlan id 10010 dstport 4789
+}
+
+protodown_basic()
+{
+	local dev=$1; shift
+
+	ip -n "$NS" link set dev "$dev" protodown on
+	check_err $? "Failed to set protodown on"
+
+	busywait "$BUSYWAIT_TIMEOUT" operstate_check "$NS" "$dev" DOWN
+	check_err $? "Operational state is not DOWN after setting protodown"
+
+	ip -n "$NS" link set dev "$dev" protodown off
+	check_err $? "Failed to set protodown off"
+
+	busywait "$BUSYWAIT_TIMEOUT" operstate_check "$NS" "$dev" UP
+	check_err $? "Operational state is not UP after clearing protodown"
+}
+
+protodown_basic_macvlan()
+{
+	RET=0
+
+	protodown_basic macvlan0
+
+	log_test "Basic protodown on/off with macvlan"
+}
+
+protodown_basic_vxlan()
+{
+	RET=0
+
+	protodown_basic vxlan0
+
+	log_test "Basic protodown on/off with vxlan"
+}
+
+protodown_reasons()
+{
+	RET=0
+
+	ip -n "$NS" link set dev macvlan0 protodown on
+
+	ip -n "$NS" link set dev macvlan0 protodown_reason 0 on
+	check_err $? "Failed to set protodown reason bit 0"
+
+	# Cannot clear protodown while reasons are active.
+	ip -n "$NS" link set dev macvlan0 protodown off 2>/dev/null
+	check_fail $? "Clearing protodown succeeded with active reasons"
+
+	ip -n "$NS" link set dev macvlan0 protodown_reason 0 off
+	check_err $? "Failed to clear protodown reason bit 0"
+
+	# Can clear protodown when no reasons are active.
+	ip -n "$NS" link set dev macvlan0 protodown off
+	check_err $? "Failed to clear protodown with no active reasons"
+
+	busywait "$BUSYWAIT_TIMEOUT" operstate_check "$NS" macvlan0 UP
+	check_err $? "Operational state is not UP after clearing protodown"
+
+	log_test "Protodown reasons"
+}
+
+protodown_lower_toggle()
+{
+	RET=0
+
+	ip -n "$NS" link set dev macvlan0 protodown on
+
+	busywait "$BUSYWAIT_TIMEOUT" operstate_check "$NS" macvlan0 DOWN
+	check_err $? "Operational state is not DOWN after setting protodown"
+
+	# Toggle carrier on the lower device. The macvlan should stay DOWN
+	# because protodown is on.
+	ip -n "$NS" link set dev dummy0 carrier off
+	ip -n "$NS" link set dev dummy0 carrier on
+
+	busywait "$BUSYWAIT_TIMEOUT" operstate_check "$NS" dummy0 UP
+	check_err $? "Lower device is not UP after carrier on"
+
+	busywait "$BUSYWAIT_TIMEOUT" operstate_check "$NS" macvlan0 DOWN
+	check_err $? "Macvlan operational state is not DOWN despite protodown"
+
+	# Clear protodown and verify the macvlan comes back up.
+	ip -n "$NS" link set dev macvlan0 protodown off
+
+	busywait "$BUSYWAIT_TIMEOUT" operstate_check "$NS" macvlan0 UP
+	check_err $? "Operational state is not UP after clearing protodown"
+
+	log_test "Protodown with lower device toggled"
+}
+
+protodown_lower_down()
+{
+	RET=0
+
+	# Bring the lower device carrier down first.
+	ip -n "$NS" link set dev dummy0 carrier off
+
+	busywait "$BUSYWAIT_TIMEOUT" operstate_check "$NS" macvlan0 LOWERLAYERDOWN
+	check_err $? "Macvlan is not LOWERLAYERDOWN with lower carrier off"
+
+	# Toggle protodown on and off while lower has no carrier. The macvlan
+	# should not transition to UP.
+	ip -n "$NS" link set dev macvlan0 protodown on
+
+	busywait "$BUSYWAIT_TIMEOUT" operstate_check "$NS" macvlan0 LOWERLAYERDOWN
+	check_err $? "Macvlan is not LOWERLAYERDOWN after setting protodown"
+
+	ip -n "$NS" link set dev macvlan0 protodown off
+
+	busywait "$BUSYWAIT_TIMEOUT" operstate_check "$NS" macvlan0 LOWERLAYERDOWN
+	check_err $? "Macvlan is not LOWERLAYERDOWN after clearing protodown"
+
+	# Bring the lower device carrier up. The macvlan should transition to
+	# UP.
+	ip -n "$NS" link set dev dummy0 carrier on
+
+	busywait "$BUSYWAIT_TIMEOUT" operstate_check "$NS" dummy0 UP
+	check_err $? "Lower device is not UP after carrier on"
+
+	busywait "$BUSYWAIT_TIMEOUT" operstate_check "$NS" macvlan0 UP
+	check_err $? "Macvlan is not UP after lower device is UP"
+
+	log_test "Protodown with lower device down"
+}
+
+trap defer_scopes_cleanup EXIT
+setup_prepare
+tests_run
+
+exit "$EXIT_STATUS"
-- 
2.54.0