selftests: rtnetlink: Add a test case for multipath route get

Without previous patch a warning would be generated upon multipath route
get when FIB multipath hash policy is to use a 5-tuple for multipath
hash calculation.
Signed-off-by: Ido Schimmel <idosch@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

tools/testing/selftests/net/rtnetlink.sh

@@ -205,6 +205,8 @@ kci_test_polrouting()
 
 kci_test_route_get()
 {
+	local hash_policy=$(sysctl -n net.ipv4.fib_multipath_hash_policy)
+
 	ret=0
 
 	ip route get 127.0.0.1 > /dev/null
@@ -223,6 +225,19 @@ kci_test_route_get()
 	check_err $?
 	ip route get 10.23.7.11 from 10.23.7.12 iif "$devdummy" > /dev/null
 	check_err $?
+	ip route add 10.23.8.0/24 \
+		nexthop via 10.23.7.13 dev "$devdummy" \
+		nexthop via 10.23.7.14 dev "$devdummy"
+	check_err $?
+	sysctl -wq net.ipv4.fib_multipath_hash_policy=0
+	ip route get 10.23.8.11 > /dev/null
+	check_err $?
+	sysctl -wq net.ipv4.fib_multipath_hash_policy=1
+	ip route get 10.23.8.11 > /dev/null
+	check_err $?
+	sysctl -wq net.ipv4.fib_multipath_hash_policy="$hash_policy"
+	ip route del 10.23.8.0/24
+	check_err $?
 	ip addr del dev "$devdummy" 10.23.7.11/24
 	check_err $?