backends/native: Ignore udev events while we're paused

When the native backend is paused we still process the udev events
even though this isn't needed and may just cause unneeded events to be
triggered afterwards.

Since we'll resume with full changes on such event, we can just block
the signal hander when paused and restore it afterwards.

As per this we can cleanup also a bit the device adding signal handling
given that now we don't have to disconnect/reconnect it again.

Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/1964>

src/backends/native/meta-backend-native.c

@@ -87,8 +87,6 @@ struct _MetaBackendNative
   MetaKms *kms;
 
   gboolean is_headless;
-
-  gulong udev_device_added_handler_id;
 };
 
 static GInitableIface *initable_parent_iface;
@@ -100,20 +98,11 @@ G_DEFINE_TYPE_WITH_CODE (MetaBackendNative, meta_backend_native, META_TYPE_BACKE
                          G_IMPLEMENT_INTERFACE (G_TYPE_INITABLE,
                                                 initable_iface_init))
 
-static void
-disconnect_udev_device_added_handler (MetaBackendNative *native);
-
 static void
 meta_backend_native_dispose (GObject *object)
 {
   MetaBackendNative *native = META_BACKEND_NATIVE (object);
 
-  if (native->udev_device_added_handler_id)
-    {
-      disconnect_udev_device_added_handler (native);
-      native->udev_device_added_handler_id = 0;
-    }
-
   if (native->kms)
     meta_kms_prepare_shutdown (native->kms);
 
@@ -485,20 +474,6 @@ on_udev_device_added (MetaUdev          *udev,
   meta_backend_add_gpu (backend, META_GPU (new_gpu_kms));
 }
 
-static void
-connect_udev_device_added_handler (MetaBackendNative *native)
-{
-  native->udev_device_added_handler_id =
-    g_signal_connect (native->udev, "device-added",
-                      G_CALLBACK (on_udev_device_added), native);
-}
-
-static void
-disconnect_udev_device_added_handler (MetaBackendNative *native)
-{
-  g_clear_signal_handler (&native->udev_device_added_handler_id, native->udev);
-}
-
 static gboolean
 init_gpus (MetaBackendNative  *native,
            GError            **error)
@@ -549,7 +524,9 @@ init_gpus (MetaBackendNative  *native,
       return FALSE;
     }
 
-  connect_udev_device_added_handler (native);
+  g_signal_connect_object (native->udev, "device-added",
+                           G_CALLBACK (on_udev_device_added), native,
+                           0);
 
   return TRUE;
 }
@@ -724,8 +701,7 @@ meta_backend_native_pause (MetaBackendNative *native)
 
   meta_seat_native_release_devices (seat);
   meta_renderer_pause (renderer);
-
+  meta_udev_pause (native->udev);
-  disconnect_udev_device_added_handler (native);
 
   meta_monitor_manager_native_pause (monitor_manager_native);
 }
@@ -749,10 +725,9 @@ void meta_backend_native_resume (MetaBackendNative *native)
                            "Backend (resume)");
 
   meta_monitor_manager_native_resume (monitor_manager_native);
+  meta_udev_resume (native->udev);
   meta_kms_resume (native->kms);
 
-  connect_udev_device_added_handler (native);
-
   meta_seat_native_reclaim_devices (seat);
   meta_renderer_resume (renderer);
 

src/backends/native/meta-udev.c

@@ -222,6 +222,18 @@ meta_udev_new (MetaBackendNative *backend_native)
   return udev;
 }
 
+void
+meta_udev_pause (MetaUdev *udev)
+{
+  g_signal_handler_block (udev->gudev_client, udev->uevent_handler_id);
+}
+
+void
+meta_udev_resume (MetaUdev *udev)
+{
+  g_signal_handler_unblock (udev->gudev_client, udev->uevent_handler_id);
+}
+
 static void
 meta_udev_finalize (GObject *object)
 {

src/backends/native/meta-udev.h

@@ -44,6 +44,10 @@ gboolean meta_udev_is_drm_device (MetaUdev    *udev,
 GList * meta_udev_list_drm_devices (MetaUdev  *udev,
                                     GError   **error);
 
+void meta_udev_pause (MetaUdev *udev);
+
+void meta_udev_resume (MetaUdev *udev);
+
 MetaUdev * meta_udev_new (MetaBackendNative *backend_native);
 
 #endif /* META_UDEV_H */