From 156c9b70dbfb83eeeff39e9202eb5f8bb6d0fd04 Mon Sep 17 00:00:00 2001 From: Andrii Nakryiko Date: Mon, 30 Nov 2020 14:33:36 -0800 Subject: [PATCH] selftests/bpf: Drain ringbuf samples at the end of test 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 Signed-off-by: Alexei Starovoitov Link: https://lore.kernel.org/bpf/20201130223336.904192-2-andrii@kernel.org --- 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); -- 2.11.0