[mutter] display: Handle late unredirect (un)inhibit calls

[Carlos Garnacho <carlosg src gnome org>]

commit f352c3d79da99e961341c1d2b5dd334dcade0271
Author: Jonas Ådahl <jadahl gmail com>
Date:   Wed Sep 25 22:23:09 2019 +0200

    display: Handle late unredirect (un)inhibit calls
    
    When tearing down, gnome-shell may call various methods a bit late,
    specifically while MetaDisplay is closing, after MetaCompositor is
    freed.
    
    Handle calls to the fullscreen unredirect inhibitation counters
    happening after MetaCompositor tear down by ignoring them. We're closing
    anyway, so it's not a problem.
    
    Fixes: https://gitlab.gnome.org/GNOME/gnome-shell/issues/1710
    
    https://gitlab.gnome.org/GNOME/mutter/merge_requests/808

 src/compositor/compositor.c | 22 ++++++++++++++++------
 1 file changed, 16 insertions(+), 6 deletions(-)
---
diff --git a/src/compositor/compositor.c b/src/compositor/compositor.c
index 1ab65ed5a..c2e2e1923 100644
--- a/src/compositor/compositor.c
+++ b/src/compositor/compositor.c
@@ -1285,9 +1285,14 @@ meta_compositor_class_init (MetaCompositorClass *klass)
 void
 meta_disable_unredirect_for_display (MetaDisplay *display)
 {
-  MetaCompositor *compositor = get_compositor_for_display (display);
-  MetaCompositorPrivate *priv =
-    meta_compositor_get_instance_private (compositor);
+  MetaCompositor *compositor;
+  MetaCompositorPrivate *priv;
+
+  if (display->closing)
+    return;
+
+  compositor = get_compositor_for_display (display);
+  priv = meta_compositor_get_instance_private (compositor);
 
   priv->disable_unredirect_count++;
 }
@@ -1302,9 +1307,14 @@ meta_disable_unredirect_for_display (MetaDisplay *display)
 void
 meta_enable_unredirect_for_display (MetaDisplay *display)
 {
-  MetaCompositor *compositor = get_compositor_for_display (display);
-  MetaCompositorPrivate *priv =
-    meta_compositor_get_instance_private (compositor);
+  MetaCompositor *compositor;
+  MetaCompositorPrivate *priv;
+
+  if (display->closing)
+    return;
+
+  compositor = get_compositor_for_display (display);
+  priv = meta_compositor_get_instance_private (compositor);
 
   if (priv->disable_unredirect_count == 0)
     g_warning ("Called enable_unredirect_for_display while unredirection is enabled.");