Commit d5444408c7 for qemu.org

commit d5444408c7ef4cc17aa02879713a6de828b94967
Author: Peter Maydell <peter.maydell@linaro.org>
Date:   Fri Mar 6 17:01:29 2026 +0000

    tests/qtest/vhost-user-test: Use g_timeout_add() to schedule connect

    In vhost-user-test, we currently create a new g_thread to run the
    connect_thread() function.  This function sleeps for 1 second, and
    then calls test_server_create_chr() to create and configure a
    chardev:

        chr = qemu_chr_new(server->chr_name, chr_path, server->context);
        g_assert(chr);

        qemu_chr_fe_init(&server->chr, chr, &error_abort);
        qemu_chr_fe_set_handlers(&server->chr, chr_can_read, chr_read,
                                 chr_event, NULL, server, server->context, true);

    This has a race condition, because when we set the
    'reconnect-ms=1000' option on the chardev the socket chardev's
    implementation handles the connect asynchronously, via a background
    thread and a callback invoked in the main-loop thread.  This means
    that that callback and the test_server_create_chr() call to
    qemu_chr_fe_set_handlers() can both enter the char-socket code
    simultaneously.  The result is random assertion failures and memory
    leaks reported by the clang address-sanitizer.

    Fix this by using g_timeout_source_new() to set up a GSource that
    will run test_server_connect() on the main-loop thread.  This ensures
    it can't execute in parallel with the callback that the socket
    chardev sets up.  This is similar to how we already handle the
    reconnect_cb() in test_reconnect().

    Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
    Reviewed-by: Fabiano Rosas <farosas@suse.de>
    Signed-off-by: Fabiano Rosas <farosas@suse.de>

diff --git a/tests/qtest/vhost-user-test.c b/tests/qtest/vhost-user-test.c
index d2bb21d5b9..c8b5f8ff71 100644
--- a/tests/qtest/vhost-user-test.c
+++ b/tests/qtest/vhost-user-test.c
@@ -930,26 +930,42 @@ reconnect_cb(gpointer user_data)
     return FALSE;
 }

-static gpointer
-connect_thread(gpointer data)
+static gboolean connect_cb(gpointer user_data)
 {
-    TestServer *s = data;
+    TestServer *s = user_data;

-    /* wait for qemu to start before first try, to avoid extra warnings */
-    g_usleep(G_USEC_PER_SEC);
     test_server_connect(s);

-    return NULL;
+    /* We only need to be called once */
+    return G_SOURCE_REMOVE;
+}
+
+/* Initial delay before connect, in milliseconds (1 second) */
+#define INITIAL_CONNECT_DELAY_MS (1 * 1000)
+
+static void test_schedule_connect(TestServer *s)
+{
+    /*
+     * Wait for a bit for QEMU to start before we first try to connect,
+     * to avoid extra warnings. We must run the "connect" on the
+     * main-loop thread so it doesn't race with a callback that
+     * the socket-chardev sets up on the main-loop.
+     */
+    GSource *src = g_timeout_source_new(INITIAL_CONNECT_DELAY_MS);
+    g_source_set_callback(src, connect_cb, s, NULL);
+    g_source_attach(src, s->context);
+    g_source_unref(src);
 }

 static void *vhost_user_test_setup_reconnect(GString *cmd_line, void *arg)
 {
     TestServer *s = test_server_new("reconnect", arg);

-    g_thread_unref(g_thread_new("connect", connect_thread, s));
     append_mem_opts(s, cmd_line, 256, TEST_MEMFD_AUTO);
     s->vu_ops->append_opts(s, cmd_line, ",server=on");

+    test_schedule_connect(s);
+
     g_test_queue_destroy(vhost_user_test_cleanup, s);

     return s;
@@ -983,10 +999,11 @@ static void *vhost_user_test_setup_connect_fail(GString *cmd_line, void *arg)

     s->test_fail = true;

-    g_thread_unref(g_thread_new("connect", connect_thread, s));
     append_mem_opts(s, cmd_line, 256, TEST_MEMFD_AUTO);
     s->vu_ops->append_opts(s, cmd_line, ",server=on");

+    test_schedule_connect(s);
+
     g_test_queue_destroy(vhost_user_test_cleanup, s);

     return s;
@@ -998,10 +1015,11 @@ static void *vhost_user_test_setup_flags_mismatch(GString *cmd_line, void *arg)

     s->test_flags = TEST_FLAGS_DISCONNECT;

-    g_thread_unref(g_thread_new("connect", connect_thread, s));
     append_mem_opts(s, cmd_line, 256, TEST_MEMFD_AUTO);
     s->vu_ops->append_opts(s, cmd_line, ",server=on");

+    test_schedule_connect(s);
+
     g_test_queue_destroy(vhost_user_test_cleanup, s);

     return s;