This adds test to check,that when poll() returns POLLIN,POLLRDNORM bits,
next read call won't block.

Signed-off-by: Arseniy Krasnov <redacted>
---
tools/testing/vsock/vsock_test.c | 107 +++++++++++++++++++++++++++++++
1 file changed, 107 insertions(+)

diff --git a/tools/testing/vsock/vsock_test.c b/tools/testing/vsock/vsock_test.c
index dc577461afc2..920dc5d5d979 100644
--- a/tools/testing/vsock/vsock_test.c
+++ b/tools/testing/vsock/vsock_test.c

@@ -18,6 +18,7 @@

#include <sys/socket.h>
#include <time.h>
#include <sys/mman.h>
+#include <poll.h>

#include "timeout.h"
#include "control.h"

@@ -596,6 +597,107 @@ static void test_seqpacket_invalid_rec_buffer_server(const struct test_opts *opt

	close(fd);
}

+static void test_stream_poll_rcvlowat_server(const struct test_opts *opts)
+{
+#define RCVLOWAT_BUF_SIZE 128
+	int fd;
+	int i;
+
+	fd = vsock_stream_accept(VMADDR_CID_ANY, 1234, NULL);
+	if (fd < 0) {
+		perror("accept");
+		exit(EXIT_FAILURE);
+	}
+
+	/* Send 1 byte. */
+	send_byte(fd, 1, 0);
+
+	control_writeln("SRVSENT");
+
+	/* Wait until client is ready to receive rest of data. */
+	control_expectln("CLNSENT");
+
+	for (i = 0; i < RCVLOWAT_BUF_SIZE - 1; i++)
+		send_byte(fd, 1, 0);
+
+	/* Keep socket in active state. */
+	control_expectln("POLLDONE");
+
+	close(fd);
+}
+
+static void test_stream_poll_rcvlowat_client(const struct test_opts *opts)
+{
+	unsigned long lowat_val = RCVLOWAT_BUF_SIZE;
+	char buf[RCVLOWAT_BUF_SIZE];
+	struct pollfd fds;
+	ssize_t read_res;
+	short poll_flags;
+	int fd;
+
+	fd = vsock_stream_connect(opts->peer_cid, 1234);
+	if (fd < 0) {
+		perror("connect");
+		exit(EXIT_FAILURE);
+	}
+
+	if (setsockopt(fd, SOL_SOCKET, SO_RCVLOWAT,
+			&lowat_val, sizeof(lowat_val))) {