test/vsock: Add retry mechanism to ioctl wrapper

Wrap the ioctl in `ioctl_int()`, which takes a pointer to the actual
int value and an expected int value. The function will not return until
either the ioctl returns the expected value or a timeout occurs, thus
avoiding immediate failure.

Signed-off-by: Xuewei Niu <niuxuewei.nxw@antgroup.com>
Reviewed-by: Stefano Garzarella <sgarzare@redhat.com>
Reviewed-by: Luigi Leonardi <leonardi@redhat.com>
Link: https://patch.msgid.link/20250708-siocinq-v6-3-3775f9a9e359@antgroup.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

Author: justxuewei

tools/testing/vsock/util.c

@@ -17,6 +17,7 @@
 #include <unistd.h>
 #include <assert.h>
 #include <sys/epoll.h>
+#include <sys/ioctl.h>
 #include <sys/mman.h>
 #include <linux/sockios.h>
 
@@ -101,28 +102,39 @@ void vsock_wait_remote_close(int fd)
 	close(epollfd);
 }
 
-/* Wait until transport reports no data left to be sent.
- * Return false if transport does not implement the unsent_bytes() callback.
+/* Wait until ioctl gives an expected int value.
+ * Return false if the op is not supported.
  */
-bool vsock_wait_sent(int fd)
+bool vsock_ioctl_int(int fd, unsigned long op, int expected)
 {
-	int ret, sock_bytes_unsent;
+	int actual, ret;
+	char name[32];
+
+	snprintf(name, sizeof(name), "ioctl(%lu)", op);
 
 	timeout_begin(TIMEOUT);
 	do {
-		ret = ioctl(fd, SIOCOUTQ, &sock_bytes_unsent);
+		ret = ioctl(fd, op, &actual);
 		if (ret < 0) {
 			if (errno == EOPNOTSUPP)
 				break;
 
-			perror("ioctl(SIOCOUTQ)");
+			perror(name);
 			exit(EXIT_FAILURE);
 		}
-		timeout_check("SIOCOUTQ");
-	} while (sock_bytes_unsent != 0);
+		timeout_check(name);
+	} while (actual != expected);
 	timeout_end();
 
-	return !ret;
+	return ret >= 0;
+}
+
+/* Wait until transport reports no data left to be sent.
+ * Return false if transport does not implement the unsent_bytes() callback.
+ */
+bool vsock_wait_sent(int fd)
+{
+	return vsock_ioctl_int(fd, SIOCOUTQ, 0);
 }
 
 /* Create socket <type>, bind to <cid, port>.

tools/testing/vsock/util.h

@@ -87,6 +87,7 @@ int vsock_stream_listen(unsigned int cid, unsigned int port);
 int vsock_seqpacket_accept(unsigned int cid, unsigned int port,
 			   struct sockaddr_vm *clientaddrp);
 void vsock_wait_remote_close(int fd);
+bool vsock_ioctl_int(int fd, unsigned long op, int expected);
 bool vsock_wait_sent(int fd);
 void send_buf(int fd, const void *buf, size_t len, int flags,
 	      ssize_t expected_ret);