[PATCH V2 5/5 nf] selftests: netfilter: add command usage

[Fabian Frederick <fabf@xxxxxxxxx>]

Avoid bad command arguments.
Based on tools/power/cpupower/bench/cpufreq-bench_plot.sh

Signed-off-by: Fabian Frederick <fabf@xxxxxxxxx>
---
V2: new patch

 tools/testing/selftests/netfilter/nft_flowtable.sh | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/tools/testing/selftests/netfilter/nft_flowtable.sh b/tools/testing/selftests/netfilter/nft_flowtable.sh
index 44a8798262369..431296c0f91cf 100755
--- a/tools/testing/selftests/netfilter/nft_flowtable.sh
+++ b/tools/testing/selftests/netfilter/nft_flowtable.sh
@@ -86,12 +86,23 @@ omtu=9000
 lmtu=1500
 rmtu=2000
 
+usage(){
+	echo "nft_flowtable.sh [OPTIONS]"
+	echo
+	echo "MTU options"
+	echo "   -o originator"
+	echo "   -l link"
+	echo "   -r responder"
+	exit 1
+}
+
 while getopts "o:l:r:" o
 do
 	case $o in
 		o) omtu=$OPTARG;;
 		l) lmtu=$OPTARG;;
 		r) rmtu=$OPTARG;;
+		*) usage;;
 	esac
 done
 
-- 
2.27.0