selftests/bpf: abstract away test log output

This patch changes how test output is printed out. By default, if test
had no errors, the only output will be a single line with test number,
name, and verdict at the end, e.g.:

  #31 xdp:OK

If test had any errors, all log output captured during test execution
will be output after test completes.

It's possible to force output of log with `-v` (`--verbose`) option, in
which case output won't be buffered and will be output immediately.

To support this, individual tests are required to use helper methods for
logging: `test__printf()` and `test__vprintf()`.

Signed-off-by: Andrii Nakryiko <andriin@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

1 files changed, 2 insertions, 6 deletions

diff --git a/tools/testing/selftests/bpf/prog_tests/send_signal.c b/tools/testing/selftests/bpf/prog_tests/send_signal.c
index 54218ee3c004..d950f4558897 100644
--- a/tools/testing/selftests/bpf/prog_tests/send_signal.c
+++ b/tools/testing/selftests/bpf/prog_tests/send_signal.c
@@ -202,8 +202,8 @@ static int test_send_signal_nmi(void)
 			 -1 /* cpu */, -1 /* group_fd */, 0 /* flags */);
 	if (pmu_fd == -1) {
 		if (errno == ENOENT) {
-			printf("%s:SKIP:no PERF_COUNT_HW_CPU_CYCLES\n",
-				__func__);
+			test__printf("%s:SKIP:no PERF_COUNT_HW_CPU_CYCLES\n",
+				     __func__);
 			return 0;
 		}
 		/* Let the test fail with a more informative message */
@@ -222,8 +222,4 @@ void test_send_signal(void)
 	ret |= test_send_signal_tracepoint();
 	ret |= test_send_signal_perf();
 	ret |= test_send_signal_nmi();
-	if (!ret)
-		printf("test_send_signal:OK\n");
-	else
-		printf("test_send_signal:FAIL\n");
 }