Commit 156c9b70 authored by Andrii Nakryiko's avatar Andrii Nakryiko Committed by Alexei Starovoitov
Browse files

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: cb1c9ddd ("selftests/bpf: Add BPF ringbuf selftests")
Signed-off-by: default avatarAndrii Nakryiko <andrii@kernel.org>
Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20201130223336.904192-2-andrii@kernel.org
parent f6a8250e

tools/testing/selftests/bpf/prog_tests/ringbuf.c

+6 −0
Original line number Diff line number Diff line
@@ -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);