[PATCH] selftests: kselftest_harness: return Kselftest Skip code for skipped tests

["Shuah Khan (Samsung OSG)" <shuah@kernel.org>]

When a test is skipped because of unmet dependencies and/or unsupported
configuration, kselftest_harness exits with error which is treated as a
fail by the Kselftest framework. This leads to false negative result even
when the test could not be run.

Change it to return kselftest skip code when a test gets skipped to
clearly report that the test could not be run. This change add skip
handling to kselftest_harness with minimal changes adding a new skipped
field to struct __test_metadata and using it to recognize KSFT_SKIP exit
from the test function (t->fn) to __run_test() to the test_harness_run()
to return the right skip code to Kselftest framework.

Kselftest framework SKIP code is 4 and the framework prints appropriate
messages to indicate that the test is skipped.

This change is tested on uevent test and the results are as follows:

Before:

TAP version 13
selftests: uevent: uevent_filtering
========================================
[==========] Running 1 tests from 1 test cases.
[ RUN      ] global.uevent_filtering
uevent_filtering.c:355:global.uevent_filtering:Uevent filtering tests require root privileges. Skipping test
global.uevent_filtering: Test skipped at step #4
[     FAIL ] global.uevent_filtering
[==========] 0 / 1 tests passed.
[  FAILED  ]
not ok 1..1 selftests: uevent: uevent_filtering [FAIL]

After:

TAP version 13
selftests: uevent: uevent_filtering
========================================
[==========] Running 1 tests from 1 test cases.
[ RUN      ] global.uevent_filtering
uevent_filtering.c:355:global.uevent_filtering:Uevent filtering tests require root privileges. Skipping test
global.uevent_filtering: Test skipped at step #4
[     SKIP ] global.uevent_filtering
not ok 1..1 selftests: uevent: uevent_filtering [SKIP]

Signed-off-by: Shuah Khan (Samsung OSG) <shuah@kernel.org>
---
 tools/testing/selftests/kselftest_harness.h | 15 +++++++++++++--
 1 file changed, 13 insertions(+), 2 deletions(-)

diff --git a/tools/testing/selftests/kselftest_harness.h b/tools/testing/selftests/kselftest_harness.h
index 6ae3730c4ee3..7af9ab97b367 100644
--- a/tools/testing/selftests/kselftest_harness.h
+++ b/tools/testing/selftests/kselftest_harness.h
@@ -631,6 +631,7 @@ struct __test_metadata {
 	void (*fn)(struct __test_metadata *);
 	int termsig;
 	int passed;
+	int skipped;
 	int trigger; /* extra handler after the evaluation */
 	__u8 step;
 	bool no_print; /* manual trigger when TH_LOG_STREAM is not available */
@@ -694,6 +695,7 @@ void __run_test(struct __test_metadata *t)
 	int status;
 
 	t->passed = 1;
+	t->skipped = 0;
 	t->trigger = 0;
 	printf("[ RUN      ] %s\n", t->name);
 	child_pid = fork();
@@ -716,9 +718,12 @@ void __run_test(struct __test_metadata *t)
 					t->name,
 					WEXITSTATUS(status));
 			} else if (!t->passed) {
+				if (WEXITSTATUS(status) == KSFT_SKIP)
+					t->skipped = 1;
 				fprintf(TH_LOG_STREAM,
-					"%s: Test failed at step #%d\n",
+					"%s: Test %s at step #%d\n",
 					t->name,
+					(t->skipped ? "skipped" : "failed"),
 					WEXITSTATUS(status));
 			}
 		} else if (WIFSIGNALED(status)) {
@@ -743,7 +748,11 @@ void __run_test(struct __test_metadata *t)
 				status);
 		}
 	}
-	printf("[     %4s ] %s\n", (t->passed ? "OK" : "FAIL"), t->name);
+	if (t->skipped)
+		printf("[     %4s ] %s\n", "SKIP", t->name);
+	else
+		printf("[     %4s ] %s\n", (t->passed ? "OK" : "FAIL"),
+			t->name);
 }
 
 static int test_harness_run(int __attribute__((unused)) argc,
@@ -762,6 +771,8 @@ static int test_harness_run(int __attribute__((unused)) argc,
 		__run_test(t);
 		if (t->passed)
 			pass_count++;
+		else if (t->skipped)
+			return KSFT_SKIP;
 		else
 			ret = 1;
 	}
-- 
2.17.0