Although documented in the comments we don't display all the various
invocations we can in the usage.

Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
---
 tests/rcutorture.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/tests/rcutorture.c b/tests/rcutorture.c
index 49311c82ea4..e8b2169e7dd 100644
--- a/tests/rcutorture.c
+++ b/tests/rcutorture.c
@@ -413,7 +413,8 @@ static void gtest_stress_10_5(void)
 
 static void usage(int argc, char *argv[])
 {
-    fprintf(stderr, "Usage: %s [nreaders [ perf | stress ] ]\n", argv[0]);
+    fprintf(stderr, "Usage: %s [nreaders [ [r|u]perf | stress [duration]]\n",
+            argv[0]);
     exit(-1);
 }
 
-- 
2.20.1