perf_counter tools: when no command is feed to perfstat, display help and exit

Signed-off-by: Wu Fengguang <fengguang.wu@intel.com>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Paul Mackerras <paulus@samba.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 3 insertions, 0 deletions

diff --git a/Documentation/perf_counter/kerneltop.c b/Documentation/perf_counter/kerneltop.c
index 0bd3c13150b1..81a68aac137f 100644
--- a/Documentation/perf_counter/kerneltop.c
+++ b/Documentation/perf_counter/kerneltop.c
@@ -387,6 +387,9 @@ int do_perfstat(int argc, char *argv[])
         argc -= optind;
         argv += optind;
 
+        if (!argc)
+                display_help();
+
         /*
          * Enable counters and exec the command:
          */