tests/channel-helper: set blocking in main thread

The /io/channel/command/echo tests run the reader side and the writer
side with the same underlying command channel. Setting the blocking mode
of the fd/handles while the other end is already reading/writing may
create issues (deadlock in win32 when earlier attempt of this series
were using SetNamedPipeHandleState). Let's just do it before spawning
the threads to avoid further concurrency issues.

Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>
Message-Id: <20221006113657.2656108-4-marcandre.lureau@redhat.com>

tests/unit/io-channel-helpers.c

@@ -25,7 +25,6 @@
 struct QIOChannelTest {
     QIOChannel *src;
     QIOChannel *dst;
-    bool blocking;
     size_t len;
     size_t niov;
     char *input;
@@ -42,8 +41,6 @@ static gpointer test_io_thread_writer(gpointer opaque)
 {
     QIOChannelTest *data = opaque;
 
-    qio_channel_set_blocking(data->src, data->blocking, NULL);
-
     qio_channel_writev_all(data->src,
                            data->inputv,
                            data->niov,
@@ -58,8 +55,6 @@ static gpointer test_io_thread_reader(gpointer opaque)
 {
     QIOChannelTest *data = opaque;
 
-    qio_channel_set_blocking(data->dst, data->blocking, NULL);
-
     qio_channel_readv_all(data->dst,
                           data->outputv,
                           data->niov,
@@ -113,7 +108,9 @@ void qio_channel_test_run_threads(QIOChannelTest *test,
 
     test->src = src;
     test->dst = dst;
-    test->blocking = blocking;
+
+    qio_channel_set_blocking(test->dst, blocking, NULL);
+    qio_channel_set_blocking(test->src, blocking, NULL);
 
     reader = g_thread_new("reader",
                           test_io_thread_reader,