[PATCH v2] perf test tsc: Fix error message report when not supported.

[Chengdong Li]

By default `perf test tsc` does not return the error message
when child process detected kernel does not support. Instead, child
process print error message to stderr, unfortunately the stderr is
redirected to /dev/null when verbose <= 0.

This patch did three things:
- returns TEST_SKIP to parent process instead of TEST_OK when
  perf_read_tsc_conversion() is not supported.
- add a new subtest of testing if TSC is supported on current
  architecture by moving exist code to a separate function.
- extended test suite definition to contain above two subtests.

Changes since v1 (thanks for the feedback from Adrian Hunter):
- rebase commit to current source.

Signed-off-by: Chengdong Li <chengdongli@xxxxxxxxxxx>
---
 tools/perf/tests/perf-time-to-tsc.c | 36 +++++++++++++++++++++--------
 1 file changed, 27 insertions(+), 9 deletions(-)

diff --git a/tools/perf/tests/perf-time-to-tsc.c b/tools/perf/tests/perf-time-to-tsc.c
index d12d0ad81801..fc7c380af5a0 100644
--- a/tools/perf/tests/perf-time-to-tsc.c
+++ b/tools/perf/tests/perf-time-to-tsc.c
@@ -47,6 +47,17 @@
 	}					\
 }
 
+static int test__tsc_is_supported(struct test_suite *test __maybe_unused,
+				  int subtest __maybe_unused)
+{
+	if (!TSC_IS_SUPPORTED) {
+		pr_debug("Test not supported on this architecture");
+		return TEST_SKIP;
+	}
+
+	return TEST_OK;
+}
+
 /**
  * test__perf_time_to_tsc - test converting perf time to TSC.
  *
@@ -70,7 +81,7 @@ static int test__perf_time_to_tsc(struct test_suite *test __maybe_unused, int su
 	struct perf_cpu_map *cpus = NULL;
 	struct evlist *evlist = NULL;
 	struct evsel *evsel = NULL;
-	int err = -1, ret, i;
+	int err = TEST_FAIL, ret, i;
 	const char *comm1, *comm2;
 	struct perf_tsc_conversion tc;
 	struct perf_event_mmap_page *pc;
@@ -79,10 +90,6 @@ static int test__perf_time_to_tsc(struct test_suite *test __maybe_unused, int su
 	u64 test_time, comm1_time = 0, comm2_time = 0;
 	struct mmap *md;
 
-	if (!TSC_IS_SUPPORTED) {
-		pr_debug("Test not supported on this architecture");
-		return TEST_SKIP;
-	}
 
 	threads = thread_map__new(-1, getpid(), UINT_MAX);
 	CHECK_NOT_NULL__(threads);
@@ -124,8 +131,8 @@ static int test__perf_time_to_tsc(struct test_suite *test __maybe_unused, int su
 	ret = perf_read_tsc_conversion(pc, &tc);
 	if (ret) {
 		if (ret == -EOPNOTSUPP) {
-			fprintf(stderr, " (not supported)");
-			return 0;
+			pr_debug("perf_read_tsc_conversion is not supported in current kernel");
+			err = TEST_SKIP;
 		}
 		goto out_err;
 	}
@@ -191,7 +198,7 @@ static int test__perf_time_to_tsc(struct test_suite *test __maybe_unused, int su
 	    test_tsc >= comm2_tsc)
 		goto out_err;
 
-	err = 0;
+	err = TEST_OK;
 
 out_err:
 	evlist__delete(evlist);
@@ -200,4 +207,15 @@ static int test__perf_time_to_tsc(struct test_suite *test __maybe_unused, int su
 	return err;
 }
 
-DEFINE_SUITE("Convert perf time to TSC", perf_time_to_tsc);
+static struct test_case time_to_tsc_tests[] = {
+	TEST_CASE_REASON("TSC support", tsc_is_supported,
+			 "This architecture does not support"),
+	TEST_CASE_REASON("Perf time to TSC", perf_time_to_tsc,
+			 "perf_read_tsc_conversion is not supported"),
+	{ .name = NULL, }
+};
+
+struct test_suite suite__perf_time_to_tsc = {
+	.desc = "Convert perf time to TSC",
+	.test_cases = time_to_tsc_tests,
+};
-- 
2.27.0