print_metric_only_json and print_metric_end in stat-display.c may
create a metric value of "none" which fails validation as isfloat. Add
a helper to properly validate metric numeric values.

Signed-off-by: Ian Rogers <irogers@google.com>
---
 tools/perf/tests/shell/lib/perf_json_output_lint.py | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/tools/perf/tests/shell/lib/perf_json_output_lint.py b/tools/perf/tests/shell/lib/perf_json_output_lint.py
index 1369baaa0361..dafbde56cc76 100644
--- a/tools/perf/tests/shell/lib/perf_json_output_lint.py
+++ b/tools/perf/tests/shell/lib/perf_json_output_lint.py
@@ -43,6 +43,9 @@ def isint(num):
 def is_counter_value(num):
   return isfloat(num) or num == '<not counted>' or num == '<not supported>'
 
+def is_metric_value(num):
+  return isfloat(num) or num == 'none'
+
 def check_json_output(expected_items):
   checks = {
       'counters': lambda x: isfloat(x),
@@ -57,7 +60,7 @@ def check_json_output(expected_items):
       'event-runtime': lambda x: isfloat(x),
       'interval': lambda x: isfloat(x),
       'metric-unit': lambda x: True,
-      'metric-value': lambda x: isfloat(x),
+      'metric-value': lambda x: is_metric_value(x),
       'metric-threshold': lambda x: x in ['unknown', 'good', 'less good', 'nearly bad', 'bad'],
       'metricgroup': lambda x: True,
       'node': lambda x: True,
-- 
2.51.2.1041.gc1ab5b90ca-goog