Fix threading conflict when doing Cycles background render

It is possible to have same image used multiple times at different frames,
which means we can not free it's buffers without any guard. From quick tests
this seems to be doing what it is supposed to.

Need more testing and port this to 2.79.

1 files changed, 13 insertions, 1 deletions

diff --git a/source/blender/blenkernel/intern/image.c b/source/blender/blenkernel/intern/image.c
index bbe6814f6b7..902076c2d14 100644
--- a/source/blender/blenkernel/intern/image.c
+++ b/source/blender/blenkernel/intern/image.c
@@ -303,8 +303,11 @@ static void image_free_anims(Image *ima)
  * Simply free the image data from memory,
  * on display the image can load again (except for render buffers).
  */
-void BKE_image_free_buffers(Image *ima)
+void BKE_image_free_buffers_ex(Image *ima, bool do_lock)
 {
+	if (do_lock) {
+		BLI_spin_lock(&image_spin);
+	}
 	image_free_cached_frames(ima);
 
 	image_free_anims(ima);
@@ -323,6 +326,15 @@ void BKE_image_free_buffers(Image *ima)
 	}
 
 	ima->ok = IMA_OK;
+
+	if (do_lock) {
+		BLI_spin_unlock(&image_spin);
+	}
+}
+
+void BKE_image_free_buffers(Image *ima)
+{
+	BKE_image_free_buffers_ex(ima, false);
 }
 
 /** Free (or release) any data used by this image (does not free the image itself). */