Fix T82607: crash cancelling Cycles render during adaptive subdivision update

Now that the Blender sync mechanism deletes nodes from the scene, we need to
ensure scene update is stopped before we do this.

Also add some more early out in scene geometry update to ensure we do not
continue working on incomplete geometry data, though that was not the cause of
this crash.

4 files changed, 53 insertions, 24 deletions

diff --git a/intern/cycles/blender/blender_session.cpp b/intern/cycles/blender/blender_session.cpp
index 513cac1e0e9..8f662c9e291 100644
--- a/intern/cycles/blender/blender_session.cpp
+++ b/intern/cycles/blender/blender_session.cpp
@@ -260,6 +260,8 @@ void BlenderSession::reset_session(BL::BlendData &b_data, BL::Depsgraph &b_depsg
 
 void BlenderSession::free_session()
 {
+  session->cancel();
+
   delete sync;
   delete session;
 }
diff --git a/intern/cycles/render/geometry.cpp b/intern/cycles/render/geometry.cpp
index fdfce63bbeb..03f10075147 100644
--- a/intern/cycles/render/geometry.cpp
+++ b/intern/cycles/render/geometry.cpp
@@ -1275,12 +1275,17 @@ void GeometryManager::device_update(Device *device,
           true_displacement_used = true;
         }
 
-        if (progress.get_cancel())
+        if (progress.get_cancel()) {
           return;
+        }
       }
     }
   }
 
+  if (progress.get_cancel()) {
+    return;
+  }
+
   /* Tessellate meshes that are using subdivision */
   if (total_tess_needed) {
     scoped_callback_timer timer([scene](double time) {
@@ -1317,10 +1322,15 @@ void GeometryManager::device_update(Device *device,
 
         i++;
 
-        if (progress.get_cancel())
+        if (progress.get_cancel()) {
           return;
+        }
       }
     }
+
+    if (progress.get_cancel()) {
+      return;
+    }
   }
 
   /* Update images needed for true displacement. */
@@ -1350,8 +1360,9 @@ void GeometryManager::device_update(Device *device,
     });
     device_update_mesh(device, dscene, scene, true, progress);
   }
-  if (progress.get_cancel())
+  if (progress.get_cancel()) {
     return;
+  }
 
   {
     scoped_callback_timer timer([scene](double time) {
@@ -1360,8 +1371,9 @@ void GeometryManager::device_update(Device *device,
       }
     });
     device_update_attributes(device, dscene, scene, progress);
-    if (progress.get_cancel())
+    if (progress.get_cancel()) {
       return;
+    }
   }
 
   /* Update displacement. */
@@ -1391,11 +1403,16 @@ void GeometryManager::device_update(Device *device,
         }
       }
 
-      if (progress.get_cancel())
+      if (progress.get_cancel()) {
         return;
+      }
     }
   }
 
+  if (progress.get_cancel()) {
+    return;
+  }
+
   /* Device re-update after displacement. */
   if (displacement_done) {
     scoped_callback_timer timer([scene](double time) {
@@ -1407,8 +1424,9 @@ void GeometryManager::device_update(Device *device,
     device_free(device, dscene);
 
     device_update_attributes(device, dscene, scene, progress);
-    if (progress.get_cancel())
+    if (progress.get_cancel()) {
       return;
+    }
   }
 
   {
@@ -1455,8 +1473,9 @@ void GeometryManager::device_update(Device *device,
     }
   }
 
-  if (progress.get_cancel())
+  if (progress.get_cancel()) {
     return;
+  }
 
   {
     scoped_callback_timer timer([scene](double time) {
@@ -1465,8 +1484,9 @@ void GeometryManager::device_update(Device *device,
       }
     });
     device_update_bvh(device, dscene, scene, progress);
-    if (progress.get_cancel())
+    if (progress.get_cancel()) {
       return;
+    }
   }
 
   {
@@ -1477,8 +1497,9 @@ void GeometryManager::device_update(Device *device,
       }
     });
     device_update_mesh(device, dscene, scene, false, progress);
-    if (progress.get_cancel())
+    if (progress.get_cancel()) {
       return;
+    }
   }
 
   need_update = false;
diff --git a/intern/cycles/render/session.cpp b/intern/cycles/render/session.cpp
index c22e29043d3..8f64495c76b 100644
--- a/intern/cycles/render/session.cpp
+++ b/intern/cycles/render/session.cpp
@@ -94,21 +94,7 @@ Session::Session(const SessionParams &params_)
 
 Session::~Session()
 {
-  if (session_thread) {
-    /* wait for session thread to end */
-    progress.set_cancel("Exiting");
-
-    gpu_need_display_buffer_update = false;
-    gpu_need_display_buffer_update_cond.notify_all();
-
-    {
-      thread_scoped_lock pause_lock(pause_mutex);
-      pause = false;
-    }
-    pause_cond.notify_all();
-
-    wait();
-  }
+  cancel();
 
   if (params.write_render_cb) {
     /* Copy to display buffer and write out image if requested */
@@ -142,6 +128,25 @@ void Session::start()
   }
 }
 
+void Session::cancel()
+{
+  if (session_thread) {
+    /* wait for session thread to end */
+    progress.set_cancel("Exiting");
+
+    gpu_need_display_buffer_update = false;
+    gpu_need_display_buffer_update_cond.notify_all();
+
+    {
+      thread_scoped_lock pause_lock(pause_mutex);
+      pause = false;
+    }
+    pause_cond.notify_all();
+
+    wait();
+  }
+}
+
 bool Session::ready_to_reset()
 {
   double dt = time_dt() - reset_time;
diff --git a/intern/cycles/render/session.h b/intern/cycles/render/session.h
index a22bf7731ae..a52082bd8cb 100644
--- a/intern/cycles/render/session.h
+++ b/intern/cycles/render/session.h
@@ -146,6 +146,7 @@ class Session {
   ~Session();
 
   void start();
+  void cancel();
   bool draw(BufferParams &params, DeviceDrawParams &draw_params);
   void wait();