Reviewed-by: Zhao Liu <zhao1.liu@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
 rust/qemu-api/tests/tests.rs | 115 ++++++++++++++++++++---------------
 1 file changed, 67 insertions(+), 48 deletions(-)

diff --git a/rust/qemu-api/tests/tests.rs b/rust/qemu-api/tests/tests.rs
index 68557fb85c7..953cb15975b 100644
--- a/rust/qemu-api/tests/tests.rs
+++ b/rust/qemu-api/tests/tests.rs
@@ -2,7 +2,7 @@
 // Author(s): Manos Pitsidianakis <manos.pitsidianakis@linaro.org>
 // SPDX-License-Identifier: GPL-2.0-or-later
 
-use std::ffi::CStr;
+use std::{cell::Cell, ffi::CStr, sync::Mutex};
 
 use qemu_api::{
     bindings::*,
@@ -14,55 +14,74 @@
     zeroable::Zeroable,
 };
 
+// Test that macros can compile.
+pub static VMSTATE: VMStateDescription = VMStateDescription {
+    name: c_str!("name").as_ptr(),
+    unmigratable: true,
+    ..Zeroable::ZERO
+};
+
+#[derive(qemu_api_macros::offsets)]
+#[repr(C)]
+#[derive(qemu_api_macros::Object)]
+pub struct DummyState {
+    parent: DeviceState,
+    migrate_clock: bool,
+}
+
+declare_properties! {
+    DUMMY_PROPERTIES,
+        define_property!(
+            c_str!("migrate-clk"),
+            DummyState,
+            migrate_clock,
+            unsafe { &qdev_prop_bool },
+            bool
+        ),
+}
+
+unsafe impl ObjectType for DummyState {
+    type Class = <DeviceState as ObjectType>::Class;
+    const TYPE_NAME: &'static CStr = c_str!("dummy");
+}
+
+impl ObjectImpl for DummyState {
+    type ParentType = DeviceState;
+    const ABSTRACT: bool = false;
+}
+
+impl DeviceImpl for DummyState {
+    fn properties() -> &'static [Property] {
+        &DUMMY_PROPERTIES
+    }
+    fn vmsd() -> Option<&'static VMStateDescription> {
+        Some(&VMSTATE)
+    }
+}
+
+fn init_qom() {
+    // Tests can run in parallel; currently they do not need the
+    // Big QEMU Lock, so use an independent mutex (LazyLock is
+    // not available until Rust 1.80.0) to serialize calls to
+    // `type_register()`.  If the tests start needing the BQL,
+    // bql_lock()/bql_unlock() can be wrapped in a similar way
+    // to `Mutex<>` and this can be changed to use a BqlCell.
+    static ONCE: Mutex<Cell<bool>> = Mutex::new(Cell::new(false));
+
+    let g = ONCE.lock().unwrap();
+    if !g.get() {
+        unsafe {
+            module_call_init(module_init_type::MODULE_INIT_QOM);
+        }
+        g.set(true);
+    }
+}
+
 #[test]
-fn test_device_decl_macros() {
-    // Test that macros can compile.
-    pub static VMSTATE: VMStateDescription = VMStateDescription {
-        name: c_str!("name").as_ptr(),
-        unmigratable: true,
-        ..Zeroable::ZERO
-    };
-
-    #[derive(qemu_api_macros::offsets)]
-    #[repr(C)]
-    #[derive(qemu_api_macros::Object)]
-    pub struct DummyState {
-        pub _parent: DeviceState,
-        pub migrate_clock: bool,
-    }
-
-    declare_properties! {
-        DUMMY_PROPERTIES,
-            define_property!(
-                c_str!("migrate-clk"),
-                DummyState,
-                migrate_clock,
-                unsafe { &qdev_prop_bool },
-                bool
-            ),
-    }
-
-    unsafe impl ObjectType for DummyState {
-        type Class = <DeviceState as ObjectType>::Class;
-        const TYPE_NAME: &'static CStr = c_str!("dummy");
-    }
-
-    impl ObjectImpl for DummyState {
-        type ParentType = DeviceState;
-        const ABSTRACT: bool = false;
-    }
-
-    impl DeviceImpl for DummyState {
-        fn properties() -> &'static [Property] {
-            &DUMMY_PROPERTIES
-        }
-        fn vmsd() -> Option<&'static VMStateDescription> {
-            Some(&VMSTATE)
-        }
-    }
-
+/// Create and immediately drop an instance.
+fn test_object_new() {
+    init_qom();
     unsafe {
-        module_call_init(module_init_type::MODULE_INIT_QOM);
         object_unref(object_new(DummyState::TYPE_NAME.as_ptr()).cast());
     }
 }
-- 
2.47.1