[PATCH net] vsock/test: Fix occasional failure in SIOCOUTQ tests
From: Konstantin Shkolnyy <hidden>
Date: 2025-05-07 11:48:53
Also in:
lkml, virtualization
Subsystem:
the rest, vm sockets (af_vsock) · Maintainers:
Linus Torvalds, Stefano Garzarella
These tests:
"SOCK_STREAM ioctl(SIOCOUTQ) 0 unsent bytes"
"SOCK_SEQPACKET ioctl(SIOCOUTQ) 0 unsent bytes"
output: "Unexpected 'SIOCOUTQ' value, expected 0, got 64 (CLIENT)".
They test that the SIOCOUTQ ioctl reports 0 unsent bytes after the data
have been received by the other side. However, sometimes there is a delay
in updating this "unsent bytes" counter, and the test fails even though
the counter properly goes to 0 several milliseconds later.
The delay occurs in the kernel because the used buffer notification
callback virtio_vsock_tx_done(), called upon receipt of the data by the
other side, doesn't update the counter itself. It delegates that to
a kernel thread (via vsock->tx_work). Sometimes that thread is delayed
more than the test expects.
Change the test to try SIOCOUTQ several times with small delays in between.
Signed-off-by: Konstantin Shkolnyy <redacted>
---
tools/testing/vsock/vsock_test.c | 26 ++++++++++++++++----------
1 file changed, 16 insertions(+), 10 deletions(-)
diff --git a/tools/testing/vsock/vsock_test.c b/tools/testing/vsock/vsock_test.c
index d0f6d253ac72..143f1cba2d18 100644
--- a/tools/testing/vsock/vsock_test.c
+++ b/tools/testing/vsock/vsock_test.c@@ -1264,21 +1264,27 @@ static void test_unsent_bytes_client(const struct test_opts *opts, int type) send_buf(fd, buf, sizeof(buf), 0, sizeof(buf)); control_expectln("RECEIVED"); - ret = ioctl(fd, SIOCOUTQ, &sock_bytes_unsent); - if (ret < 0) { - if (errno == EOPNOTSUPP) { - fprintf(stderr, "Test skipped, SIOCOUTQ not supported.\n"); - } else { + /* SIOCOUTQ isn't guaranteed to instantly track sent data */ + for (int i = 0; i < 10; i++) { + ret = ioctl(fd, SIOCOUTQ, &sock_bytes_unsent); + if (ret == 0 && sock_bytes_unsent == 0) + goto success; + + if (ret < 0) { + if (errno == EOPNOTSUPP) { + fprintf(stderr, "Test skipped, SIOCOUTQ not supported.\n"); + goto success; + } perror("ioctl"); exit(EXIT_FAILURE); } - } else if (ret == 0 && sock_bytes_unsent != 0) { - fprintf(stderr, - "Unexpected 'SIOCOUTQ' value, expected 0, got %i\n", - sock_bytes_unsent); - exit(EXIT_FAILURE); + usleep(10 * 1000); } + fprintf(stderr, "Unexpected 'SIOCOUTQ' value, expected 0, got %i\n", + sock_bytes_unsent); + exit(EXIT_FAILURE); +success: close(fd); }
--
2.34.1