selftests: rtnetlink: Add operational state test

Virtual devices (e.g., VXLAN) that do not have a notion of a carrier are
created with an "UNKNOWN" operational state which some users find
confusing [1].

It is possible to set the operational state from user space either
during device creation or afterwards and some applications will start
doing that in order to avoid the above problem.

Add a test for this functionality to ensure it does not regress.

[1] https://lore.kernel.org/netdev/[email protected]/

Reviewed-by: Petr Machata <[email protected]>
Signed-off-by: Ido Schimmel <[email protected]>
Reviewed-by: Simon Horman <[email protected]>
Link: https://patch.msgid.link/[email protected]
Signed-off-by: Jakub Kicinski <[email protected]>

Author: idosch

tools/testing/selftests/net/rtnetlink.sh

@@ -30,6 +30,7 @@ ALL_TESTS="
 	kci_test_address_proto
 	kci_test_enslave_bonding
 	kci_test_mngtmpaddr
+	kci_test_operstate
 "
 
 devdummy="test-dummy0"
@@ -1344,6 +1345,39 @@ kci_test_mngtmpaddr()
 	return $ret
 }
 
+kci_test_operstate()
+{
+	local ret=0
+
+	# Check that it is possible to set operational state during device
+	# creation and that it is preserved when the administrative state of
+	# the device is toggled.
+	run_cmd ip link add name vx0 up state up type vxlan id 10010 dstport 4789
+	run_cmd_grep "state UP" ip link show dev vx0
+	run_cmd ip link set dev vx0 down
+	run_cmd_grep "state DOWN" ip link show dev vx0
+	run_cmd ip link set dev vx0 up
+	run_cmd_grep "state UP" ip link show dev vx0
+
+	run_cmd ip link del dev vx0
+
+	# Check that it is possible to set the operational state of the device
+	# after creation.
+	run_cmd ip link add name vx0 up type vxlan id 10010 dstport 4789
+	run_cmd_grep "state UNKNOWN" ip link show dev vx0
+	run_cmd ip link set dev vx0 state up
+	run_cmd_grep "state UP" ip link show dev vx0
+
+	run_cmd ip link del dev vx0
+
+	if [ "$ret" -ne 0 ]; then
+		end_test "FAIL: operstate"
+		return 1
+	fi
+
+	end_test "PASS: operstate"
+}
+
 kci_test_rtnl()
 {
 	local current_test