[mutter] renderer/native: Don't clear GPU data with pending page flips

[Marge Bot <marge-bot src gnome org>]

commit 287908e05ad310f3c27009a4ca6bfb40ee65c973
Author: Jonas Ådahl <jadahl gmail com>
Date:   Thu Dec 9 11:18:21 2021 +0100

    renderer/native: Don't clear GPU data with pending page flips
    
    An incorrect assumption that after mode set there would be no pending
    page flips was made. This meant that if there was a mode set, followed
    by a page flip, if that page flip was for a CRTC on a now unused GPU,
    we'd crash due to the renderer GPU data having already been freed. This
    commit avoids that by keeping it alive as long as the page flips are
    still in the air. It fixes crashes with backtraces such as
    
      0) meta_render_device_get_egl_display (render_device=0x0)
         at ../src/backends/native/meta-render-device.c:320
      1) secondary_gpu_state_free (secondary_gpu_state=0x1c8cc30)
         at ../src/backends/native/meta-onscreen-native.c:560
      2) meta_onscreen_native_dispose (object=0x1cb65e0)
         at ../src/backends/native/meta-onscreen-native.c:2168
      3) g_object_unref (_object=<optimized out>)
         at ../gobject/gobject.c:3540
      4) g_object_unref (_object=0x1cb65e0)
         at ../gobject/gobject.c:3470
      5) clutter_stage_view_finalize (object=0x1cbb450)
         at ../clutter/clutter/clutter-stage-view.c:1412
      6) g_object_unref (_object=<optimized out>)
         at ../gobject/gobject.c:3578
      7) g_object_unref (_object=0x1cbb450)
         at ../gobject/gobject.c:3470
      8) meta_kms_page_flip_closure_free (closure=0x1d47e60)
         at ../src/backends/native/meta-kms-page-flip.c:76
      9) g_list_foreach (list=<optimized out>, func=0x7fb3ada67111 <meta_kms_page_flip_closure_free>, 
user_data=0x0)
         at ../glib/glist.c:1090
     10) g_list_free_full (list=0x1cb4d20 = {...}, free_func=<optimized out>)
         at ../glib/glist.c:244
     11) meta_kms_page_flip_data_unref (page_flip_data=0x1c65510)
         at ../src/backends/native/meta-kms-page-flip.c:109
     12) meta_kms_callback_data_free (callback_data=0x227ebf0)
         at ../src/backends/native/meta-kms.c:372
     13) flush_callbacks (kms=0x18e2630)
         at ../src/backends/native/meta-kms.c:391
     14) callback_idle (user_data=0x18e2630)
         at ../src/backends/native/meta-kms.c
    
    Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/2147>

 src/backends/native/meta-onscreen-native.c |  6 +++
 src/backends/native/meta-onscreen-native.h |  2 +
 src/backends/native/meta-renderer-native.c | 74 ++++++++++++++++++++++++++----
 3 files changed, 73 insertions(+), 9 deletions(-)
---
diff --git a/src/backends/native/meta-onscreen-native.c b/src/backends/native/meta-onscreen-native.c
index 763eb559e1..cc2a8ca763 100644
--- a/src/backends/native/meta-onscreen-native.c
+++ b/src/backends/native/meta-onscreen-native.c
@@ -2219,3 +2219,9 @@ meta_onscreen_native_class_init (MetaOnscreenNativeClass *klass)
     meta_onscreen_native_swap_buffers_with_damage;
   onscreen_class->direct_scanout = meta_onscreen_native_direct_scanout;
 }
+
+MetaCrtc *
+meta_onscreen_native_get_crtc (MetaOnscreenNative *onscreen_native)
+{
+  return onscreen_native->crtc;
+}
diff --git a/src/backends/native/meta-onscreen-native.h b/src/backends/native/meta-onscreen-native.h
index 020fc8a14a..5c99181d39 100644
--- a/src/backends/native/meta-onscreen-native.h
+++ b/src/backends/native/meta-onscreen-native.h
@@ -56,4 +56,6 @@ MetaOnscreenNative * meta_onscreen_native_new (MetaRendererNative *renderer_nati
                                                int                 width,
                                                int                 height);
 
+MetaCrtc * meta_onscreen_native_get_crtc (MetaOnscreenNative *onscreen_native);
+
 #endif /* META_ONSCREEN_NATIVE_H */
diff --git a/src/backends/native/meta-renderer-native.c b/src/backends/native/meta-renderer-native.c
index 440b33c0d6..b38fceecf6 100644
--- a/src/backends/native/meta-renderer-native.c
+++ b/src/backends/native/meta-renderer-native.c
@@ -93,6 +93,8 @@ struct _MetaRendererNative
   gboolean pending_mode_set;
 
   GList *kept_alive_onscreens;
+  GList *lingering_onscreens;
+  guint release_unused_gpus_idle_id;
 
   GList *power_save_page_flip_onscreens;
   guint power_save_page_flip_source_id;
@@ -688,13 +690,6 @@ meta_renderer_native_queue_power_save_page_flip (MetaRendererNative *renderer_na
                     g_object_ref (onscreen));
 }
 
-static void
-clear_kept_alive_onscreens (MetaRendererNative *renderer_native)
-{
-  g_clear_list (&renderer_native->kept_alive_onscreens,
-                g_object_unref);
-}
-
 static gboolean
 is_gpu_unused (gpointer key,
                gpointer value,
@@ -728,11 +723,70 @@ free_unused_gpu_datas (MetaRendererNative *renderer_native)
       g_hash_table_add (used_gpus, gpu);
     }
 
+  for (l = renderer_native->lingering_onscreens; l; l = l->next)
+    {
+      MetaOnscreenNative *onscreen_native = META_ONSCREEN_NATIVE (l->data);
+      MetaCrtc *crtc = meta_onscreen_native_get_crtc (onscreen_native);
+
+      g_hash_table_add (used_gpus, meta_crtc_get_gpu (crtc));
+    }
+
   g_hash_table_foreach_remove (renderer_native->gpu_datas,
                                is_gpu_unused,
                                used_gpus);
 }
 
+static gboolean
+release_unused_gpus_idle (gpointer user_data)
+{
+  MetaRendererNative *renderer_native = META_RENDERER_NATIVE (user_data);
+
+  renderer_native->release_unused_gpus_idle_id = 0;
+  free_unused_gpu_datas (renderer_native);
+
+  return G_SOURCE_REMOVE;
+}
+
+static void
+old_onscreen_freed (gpointer  user_data,
+                    GObject  *freed_onscreen)
+{
+  MetaRendererNative *renderer_native = META_RENDERER_NATIVE (user_data);
+
+  renderer_native->lingering_onscreens =
+    g_list_remove (renderer_native->lingering_onscreens, freed_onscreen);
+
+  if (!renderer_native->release_unused_gpus_idle_id)
+    {
+      renderer_native->release_unused_gpus_idle_id =
+        g_idle_add (release_unused_gpus_idle, renderer_native);
+    }
+}
+
+static void
+clear_kept_alive_onscreens (MetaRendererNative *renderer_native)
+{
+  GList *l;
+
+  for (l = renderer_native->kept_alive_onscreens; l; l = l->next)
+    {
+      CoglOnscreen *onscreen;
+
+      if (!COGL_IS_ONSCREEN (l->data))
+        continue;
+
+      onscreen = COGL_ONSCREEN (l->data);
+      g_object_weak_ref (G_OBJECT (onscreen),
+                         old_onscreen_freed,
+                         renderer_native);
+      renderer_native->lingering_onscreens =
+        g_list_prepend (renderer_native->lingering_onscreens, onscreen);
+    }
+
+  g_clear_list (&renderer_native->kept_alive_onscreens,
+                g_object_unref);
+}
+
 void
 meta_renderer_native_post_mode_set_updates (MetaRendererNative *renderer_native)
 {
@@ -2061,8 +2115,6 @@ meta_renderer_native_finalize (GObject *object)
 {
   MetaRendererNative *renderer_native = META_RENDERER_NATIVE (object);
 
-  clear_kept_alive_onscreens (renderer_native);
-
   g_clear_list (&renderer_native->power_save_page_flip_onscreens,
                 g_object_unref);
   g_clear_handle_id (&renderer_native->power_save_page_flip_source_id,
@@ -2070,6 +2122,10 @@ meta_renderer_native_finalize (GObject *object)
 
   g_list_free (renderer_native->pending_mode_set_views);
 
+  g_clear_handle_id (&renderer_native->release_unused_gpus_idle_id,
+                     g_source_remove);
+  clear_kept_alive_onscreens (renderer_native);
+
   g_hash_table_destroy (renderer_native->gpu_datas);
   g_clear_object (&renderer_native->gles3);