wait-for-sync-obj: clear tasks on shutdown

src/state.rs

@@ -1073,6 +1073,7 @@ impl State {
         self.cursor_user_groups.clear();
         self.cursor_user_group_hardware_cursor.take();
         self.cpu_worker.clear();
+        self.wait_for_sync_obj.clear();
     }
 
     pub fn remove_toplevel_id(&self, id: ToplevelIdentifier) {

src/video/drm/wait_for_sync_obj.rs

@@ -87,6 +87,12 @@ impl WaitForSyncObj {
         }
     }
 
+    pub fn clear(&self) {
+        self.inner.ctx.take();
+        self.inner.busy.clear();
+        self.inner.idle.take();
+    }
+
     pub fn set_ctx(&self, ctx: Option<Rc<SyncObjCtx>>) {
         self.inner.ctx.set(ctx);
         let busy_waiters: Vec<_> = self.inner.busy.lock().drain_values().collect();
@@ -163,13 +169,6 @@ impl WaitForSyncObj {
     }
 }
 
-impl Drop for WaitForSyncObj {
-    fn drop(&mut self) {
-        self.inner.busy.clear();
-        self.inner.idle.take();
-    }
-}
-
 impl WaiterInner {
     async fn run(self: Rc<Self>) {
         let mut buf = Buf::new(8);