From 495f4ee1e5df81ccce9793aeee4d52700aed7160 Mon Sep 17 00:00:00 2001
From: Xavier Hallade <me@ph0b.com>
Date: Wed, 9 Jul 2025 14:36:45 +0200
Subject: [PATCH] 4.2LTS: Fix #141171: oneAPI: Rendering artifacts in
 barbershop scene

max_shaders was not updated when Embree was disabled.

Backported from: 7691e6520b213e3b685cf1d6130ad0d0de0c7cf6

Pull Request: https://projects.blender.org/blender/blender/pulls/141230
---
 intern/cycles/device/oneapi/device_impl.cpp | 19 +++++++++++--------
 1 file changed, 11 insertions(+), 8 deletions(-)

diff --git a/intern/cycles/device/oneapi/device_impl.cpp b/intern/cycles/device/oneapi/device_impl.cpp
index d062c435345..b28a6976070 100644
--- a/intern/cycles/device/oneapi/device_impl.cpp
+++ b/intern/cycles/device/oneapi/device_impl.cpp
@@ -529,18 +529,21 @@ void OneapiDevice::const_copy_to(const char *name, void *host, size_t size)
              << string_human_readable_number(size) << " bytes. ("
              << string_human_readable_size(size) << ")";
 
-#  ifdef WITH_EMBREE_GPU
-  if (embree_scene != nullptr && strcmp(name, "data") == 0) {
+  if (strcmp(name, "data") == 0) {
     assert(size <= sizeof(KernelData));
+    KernelData *const data = static_cast<KernelData *>(host);
 
-    /* Update scene handle(since it is different for each device on multi devices) */
-    KernelData *const data = (KernelData *)host;
-    data->device_bvh = embree_scene;
-
-    /* We need this number later for proper local memory allocation. */
+    /* We need this value when allocating local memory for integrator_sort_bucket_pass
+     * and integrator_sort_write_pass kernels. */
     scene_max_shaders_ = data->max_shaders;
-  }
+
+#  ifdef WITH_EMBREE_GPU
+    if (embree_scene != nullptr) {
+      /* Update scene handle(since it is different for each device on multi devices) */
+      data->device_bvh = embree_scene;
+    }
 #  endif
+  }
 
   ConstMemMap::iterator i = const_mem_map_.find(name);
   device_vector<uchar> *data;