From 96ea4fa60c4528d95bdbce7f4212c015ab3e8113 Mon Sep 17 00:00:00 2001 From: Jakub Kicinski Date: Tue, 6 Jan 2026 12:02:05 -0800 Subject: [PATCH] selftests: tls: avoid flakiness in data_steal We see the following failure a few times a week: # RUN global.data_steal ... # tls.c:3280:data_steal:Expected recv(cfd, buf2, sizeof(buf2), MSG_DONTWAIT) (10000) == -1 (-1) # data_steal: Test failed # FAIL global.data_steal not ok 8 global.data_steal The 10000 bytes read suggests that the child process did a recv() of half of the data using the TLS ULP and we're now getting the remaining half. The intent of the test is to get the child to enter _TCP_ recvmsg handler, so it needs to enter the syscall before parent installed the TLS recvmsg with setsockopt(SOL_TLS). Instead of the 10msec sleep send 1 byte of data and wait for the child to consume it. Reviewed-by: Sabrina Dubroca Link: https://patch.msgid.link/20260106200205.1593915-1-kuba@kernel.org Signed-off-by: Jakub Kicinski --- tools/testing/selftests/net/tls.c | 16 ++++++++++++---- 1 file changed, 12 insertions(+), 4 deletions(-) diff --git a/tools/testing/selftests/net/tls.c b/tools/testing/selftests/net/tls.c index a4d16a460fbe4..9e2ccea13d702 100644 --- a/tools/testing/selftests/net/tls.c +++ b/tools/testing/selftests/net/tls.c @@ -3260,17 +3260,25 @@ TEST(data_steal) { ASSERT_EQ(setsockopt(cfd, IPPROTO_TCP, TCP_ULP, "tls", sizeof("tls")), 0); /* Spawn a child and get it into the read wait path of the underlying - * TCP socket. + * TCP socket (before kernel .recvmsg is replaced with the TLS one). */ pid = fork(); ASSERT_GE(pid, 0); if (!pid) { - EXPECT_EQ(recv(cfd, buf, sizeof(buf) / 2, MSG_WAITALL), - sizeof(buf) / 2); + EXPECT_EQ(recv(cfd, buf, sizeof(buf) / 2 + 1, MSG_WAITALL), + sizeof(buf) / 2 + 1); exit(!__test_passed(_metadata)); } - usleep(10000); + /* Send a sync byte and poll until it's consumed to ensure + * the child is in recv() before we proceed to install TLS. + */ + ASSERT_EQ(send(fd, buf, 1, 0), 1); + do { + usleep(500); + } while (recv(cfd, buf, 1, MSG_PEEK | MSG_DONTWAIT) == 1); + EXPECT_EQ(errno, EAGAIN); + ASSERT_EQ(setsockopt(fd, SOL_TLS, TLS_TX, &tls, tls.len), 0); ASSERT_EQ(setsockopt(cfd, SOL_TLS, TLS_RX, &tls, tls.len), 0); -- 2.47.3