perf list: Add usage

Currently 'perf list' is not very helpful if you forget the syntax:

  $ perf list -h

  List of pre-defined events (to be used in -e):

After:
  $ perf list -h

   usage: perf list [hw|sw|cache|tracepoint|pmu|event_glob]

Signed-off-by: David Ahern <dsahern@gmail.com>
Acked-by: Ingo Molnar <mingo@kernel.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Link: http://lkml.kernel.org/r/527133AD.4030003@gmail.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

1 files changed, 14 insertions, 3 deletions

diff --git a/tools/perf/builtin-list.c b/tools/perf/builtin-list.c
index 45000e7d4398..011195e38f21 100644
--- a/tools/perf/builtin-list.c
+++ b/tools/perf/builtin-list.c
@@ -14,20 +14,31 @@
 #include "util/parse-events.h"
 #include "util/cache.h"
 #include "util/pmu.h"
+#include "util/parse-options.h"
 
 int cmd_list(int argc, const char **argv, const char *prefix __maybe_unused)
 {
         int i;
+        const struct option list_options[] = {
+                OPT_END()
+        };
+        const char * const list_usage[] = {
+                "perf list [hw|sw|cache|tracepoint|pmu|event_glob]",
+                NULL
+        };
+
+        argc = parse_options(argc, argv, list_options, list_usage,
+                             PARSE_OPT_STOP_AT_NON_OPTION);
 
         setup_pager();
 
-        if (argc == 1) {
+        if (argc == 0) {
                 print_events(NULL, false);
                 return 0;
         }
 
-        for (i = 1; i < argc; ++i) {
-                if (i > 2)
+        for (i = 0; i < argc; ++i) {
+                if (i)
                         putchar('\n');
                 if (strncmp(argv[i], "tracepoint", 10) == 0)
                         print_tracepoint_events(NULL, NULL, false);