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From: Andrii Nakryiko <andriin@fb.com>
To: <bpf@vger.kernel.org>, <netdev@vger.kernel.org>, <ast@fb.com>,
Cc: <andrii.nakryiko@gmail.com>, <kernel-team@fb.com>,
	Andrii Nakryiko <andriin@fb.com>
Subject: [PATCH bpf-next 1/3] selftests/bpf: fix race in tcp_rtt test
Date: Fri, 13 Mar 2020 18:39:30 -0700	[thread overview]
Message-ID: <20200314013932.4035712-1-andriin@fb.com> (raw)

Previous attempt to make tcp_rtt more robust introduced a new race, in which
server_done might be set to true before server can actually accept any
connection. Fix this by unconditionally waiting for accept(). Given socket is
non-blocking, if there are any problems with client side, it should eventually
close listening FD and let server thread exit with failure.

Fixes: 4cd729fa022c ("selftests/bpf: Make tcp_rtt test more robust to failures")
Signed-off-by: Andrii Nakryiko <andriin@fb.com>
 tools/testing/selftests/bpf/prog_tests/tcp_rtt.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/tools/testing/selftests/bpf/prog_tests/tcp_rtt.c b/tools/testing/selftests/bpf/prog_tests/tcp_rtt.c
index e08f6bb17700..e56b52ab41da 100644
--- a/tools/testing/selftests/bpf/prog_tests/tcp_rtt.c
+++ b/tools/testing/selftests/bpf/prog_tests/tcp_rtt.c
@@ -226,7 +226,7 @@ static void *server_thread(void *arg)
 		return ERR_PTR(err);
-	while (!server_done) {
+	while (true) {
 		client_fd = accept(fd, (struct sockaddr *)&addr, &len);
 		if (client_fd == -1 && errno == EAGAIN) {
@@ -272,7 +272,7 @@ void test_tcp_rtt(void)
 	CHECK_FAIL(run_test(cgroup_fd, server_fd));
 	server_done = true;
-	pthread_join(tid, &server_res);
+	CHECK_FAIL(pthread_join(tid, &server_res));

             reply	other threads:[~2020-03-14  1:39 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-03-14  1:39 Andrii Nakryiko [this message]
2020-03-14  1:39 ` [PATCH bpf-next 2/3] selftests/bpf: fix test_progs's parsing of test numbers Andrii Nakryiko
2020-03-17  5:28   ` Martin KaFai Lau
2020-03-14  1:39 ` [PATCH bpf-next 3/3] selftests/bpf: reset process and thread affinity after each test/sub-test Andrii Nakryiko
2020-03-17  5:35   ` [Potential Spoof] " Martin KaFai Lau
2020-03-17  5:39     ` Andrii Nakryiko
2020-03-17  5:27 ` [Potential Spoof] [PATCH bpf-next 1/3] selftests/bpf: fix race in tcp_rtt test Martin KaFai Lau
2020-03-17 18:58 ` Daniel Borkmann

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