This happens on 64-bit big-endian machines.
SO_RCVLOWAT requires an int parameter. However, instead of int, the test
uses unsigned long in one place and size_t in another. Both are 8 bytes
long on 64-bit machines. The kernel, having received the 8 bytes, doesn't
test for the exact size of the parameter, it only cares that it's >=
sizeof(int), and casts the 4 lower-addressed bytes to an int, which, on
a big-endian machine, contains 0. 0 doesn't trigger an error, SO_RCVLOWAT
returns with success and the socket stays with the default SO_RCVLOWAT = 1,
which results in test failures.
Fixes: b1346338fbae ("vsock_test: POLLIN + SO_RCVLOWAT test")
Fixes: 542e893fbadc ("vsock/test: two tests to check credit update logic")
Signed-off-by: Konstantin Shkolnyy <kshk@xxxxxxxxxxxxx>
---
Notes:
The problem was found on s390 (big endian), while x86-64 didn't show it. After this fix, all tests pass on s390.
Changes for v2:
- add "Fixes:" lines to the commit message
tools/testing/vsock/vsock_test.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/tools/testing/vsock/vsock_test.c b/tools/testing/vsock/vsock_test.c
index 8d38dbf8f41f..7fd25b814b4b 100644
--- a/tools/testing/vsock/vsock_test.c
+++ b/tools/testing/vsock/vsock_test.c
@@ -835,7 +835,7 @@ static void test_stream_poll_rcvlowat_server(const struct test_opts *opts)
static void test_stream_poll_rcvlowat_client(const struct test_opts *opts)
{
- unsigned long lowat_val = RCVLOWAT_BUF_SIZE;
+ int lowat_val = RCVLOWAT_BUF_SIZE;
char buf[RCVLOWAT_BUF_SIZE];
struct pollfd fds;
short poll_flags;
@@ -1357,7 +1357,7 @@ static void test_stream_rcvlowat_def_cred_upd_client(const struct test_opts *opt
static void test_stream_credit_update_test(const struct test_opts *opts,
bool low_rx_bytes_test)
{
- size_t recv_buf_size;
+ int recv_buf_size;
struct pollfd fds;
size_t buf_size;
void *buf;
--
2.34.1
