Avoid occasional test failures due to the last sample being delayed to
another ring_buffer__poll() call. Instead, drain samples completely with
ring_buffer__consume(). This is supposed to fix a rare and non-deterministic
test failure in libbpf CI.
Fixes: cb1c9ddd5525 ("selftests/bpf: Add BPF ringbuf selftests")
Signed-off-by: Andrii Nakryiko <andrii@xxxxxxxxxx>
---
tools/testing/selftests/bpf/prog_tests/ringbuf.c | 6 ++++++
1 file changed, 6 insertions(+)
diff --git a/tools/testing/selftests/bpf/prog_tests/ringbuf.c b/tools/testing/selftests/bpf/prog_tests/ringbuf.c
index 1a48c6f7f54e..fddbc5db5d6a 100644
--- a/tools/testing/selftests/bpf/prog_tests/ringbuf.c
+++ b/tools/testing/selftests/bpf/prog_tests/ringbuf.c
@@ -220,6 +220,12 @@ void test_ringbuf(void)
if (CHECK(bg_ret <= 0, "bg_ret", "epoll_wait result: %ld", bg_ret))
goto cleanup;
+ /* due to timing variations, there could still be non-notified
+ * samples, so consume them here to collect all the samples
+ */
+ err = ring_buffer__consume(ringbuf);
+ CHECK(err < 0, "rb_consume", "failed: %d\b", err);
+
/* 3 rounds, 2 samples each */
cnt = atomic_xchg(&sample_cnt, 0);
CHECK(cnt != 6, "cnt", "exp %d samples, got %d\n", 6, cnt);
--
2.24.1
