xwayland: Delete all frame_callback_list nodes in xwl_unrealize_window

We were only calling xwl_present_unrealize_window for the toplevel
window, but the list can contain entries from child windows as well,
in which case we were leaving dangling pointers to freed memory.

Closes: #1000
Fixes: c5067fea "xwayland: Use single frame callback for Present
                     flips and normal updates"
Reviewed-by: Olivier Fourdan <ofourdan@redhat.com>
Tested-by: Olivier Fourdan <ofourdan@redhat.com>

hw/xwayland/xwayland-present.c

@@ -524,14 +524,8 @@ xwl_present_flips_stop(WindowPtr window)
 }
 
 void
-xwl_present_unrealize_window(WindowPtr window)
+xwl_present_unrealize_window(struct xwl_present_window *xwl_present_window)
 {
-    struct xwl_present_window *xwl_present_window = xwl_present_window_priv(window);
-
-    if (!xwl_present_window ||
-        xorg_list_is_empty(&xwl_present_window->frame_callback_list))
-        return;
-
     /* The pending frame callback may never be called, so drop it and shorten
      * the frame timer interval.
      */

hw/xwayland/xwayland-present.h

@@ -67,7 +67,7 @@ struct xwl_present_event {
 void xwl_present_frame_callback(struct xwl_present_window *xwl_present_window);
 Bool xwl_present_init(ScreenPtr screen);
 void xwl_present_cleanup(WindowPtr window);
-void xwl_present_unrealize_window(WindowPtr window);
+void xwl_present_unrealize_window(struct xwl_present_window *xwl_present_window);
 
 #endif /* GLAMOR_HAS_GBM */
 

hw/xwayland/xwayland-window.c

@@ -607,8 +607,15 @@ xwl_unrealize_window(WindowPtr window)
         wl_callback_destroy(xwl_window->frame_callback);
 
 #ifdef GLAMOR_HAS_GBM
-    if (xwl_screen->present)
-        xwl_present_unrealize_window(window);
+    if (xwl_screen->present) {
+        struct xwl_present_window *xwl_present_window, *tmp;
+
+        xorg_list_for_each_entry_safe(xwl_present_window, tmp,
+                                      &xwl_window->frame_callback_list,
+                                      frame_callback_list) {
+            xwl_present_unrealize_window(xwl_present_window);
+        }
+    }
 #endif
 
     free(xwl_window);