On Wed, May 07, 2025 at 06:48:33AM -0500, Konstantin Shkolnyy wrote:
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 <kshk@xxxxxxxxxxxxx>
---
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);
I worked on something similar but I didn't yet send it.
I like the delay you put, but I prefer to use the timeout stuff we have
to retry, like I did here:
@@ -1264,20 +1270,25 @@ static void test_unsent_bytes_client(const struct test_opts *op
ts, 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 {
- perror("ioctl");
- exit(EXIT_FAILURE);
+ /* Although we have a control message, we are not sure that the vsock
+ * transport has sent us notification that the buffer has been copied
+ * and cleared, so in some cases we may still see unsent bytes.
+ * Better to do a few iterations to be sure.
+ */
+ timeout_begin(TIMEOUT);
+ do {
+ ret = ioctl(fd, SIOCOUTQ, &sock_bytes_unsent);
+ if (ret < 0) {
+ if (errno == EOPNOTSUPP) {
+ fprintf(stderr, "Test skipped, SIOCOUTQ not supported.\n");
+ break;
+ } else {
+ 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);
- }
+ } while (sock_bytes_unsent != 0);
+ timeout_end();
What about combining the two?
Thanks,
Stefano
