Fix T63178 Eevee animation render crash

If image buffer is not loaded and blender attempts to reload it (during
`BKE_image_acquire_ibuf`) over and over for each frame rendered.
When attempting this reload, image_load_image_file is calling
`BKE_image_free_buffers` and tag the Image to the (GPU) image_free_queue
(because this run on the rendering thread).

If the main thread decide to redraw the UI and go through `GPU_free_unused_buffers` they all get deleted and if that happens before the rendering thread use them ... segfault.

If I replace the environment textures with correct ones (the file does not seems to contain them), there is no crash when rendering.

I used a list of GPUTexture from blender Image to increase and decrease the
reference counter correctly.

This add very little memory and computation overhead.

3 files changed, 15 insertions, 4 deletions

diff --git a/source/blender/gpu/GPU_viewport.h b/source/blender/gpu/GPU_viewport.h
index 23e5ee28533..198a9ec98e2 100644
--- a/source/blender/gpu/GPU_viewport.h
+++ b/source/blender/gpu/GPU_viewport.h
@@ -42,6 +42,7 @@ typedef struct ViewportMemoryPool {
   struct BLI_mempool *shgroups;
   struct BLI_mempool *uniforms;
   struct BLI_mempool *passes;
+  struct BLI_mempool *images;
 } ViewportMemoryPool;
 
 /* All FramebufferLists are just the same pointers with different names */
diff --git a/source/blender/gpu/intern/gpu_draw.c b/source/blender/gpu/intern/gpu_draw.c
index e25c7d7f11e..edc2f2171a5 100644
--- a/source/blender/gpu/intern/gpu_draw.c
+++ b/source/blender/gpu/intern/gpu_draw.c
@@ -1199,12 +1199,13 @@ void GPU_free_smoke_velocity(SmokeModifierData *smd)
 }
 
 static LinkNode *image_free_queue = NULL;
+static ThreadMutex img_queue_mutex = BLI_MUTEX_INITIALIZER;
 
 static void gpu_queue_image_for_free(Image *ima)
 {
-  BLI_thread_lock(LOCK_OPENGL);
+  BLI_mutex_lock(&img_queue_mutex);
   BLI_linklist_prepend(&image_free_queue, ima);
-  BLI_thread_unlock(LOCK_OPENGL);
+  BLI_mutex_unlock(&img_queue_mutex);
 }
 
 void GPU_free_unused_buffers(Main *bmain)
@@ -1213,7 +1214,7 @@ void GPU_free_unused_buffers(Main *bmain)
     return;
   }
 
-  BLI_thread_lock(LOCK_OPENGL);
+  BLI_mutex_lock(&img_queue_mutex);
 
   /* images */
   for (LinkNode *node = image_free_queue; node; node = node->next) {
@@ -1228,7 +1229,7 @@ void GPU_free_unused_buffers(Main *bmain)
   BLI_linklist_free(image_free_queue, NULL);
   image_free_queue = NULL;
 
-  BLI_thread_unlock(LOCK_OPENGL);
+  BLI_mutex_unlock(&img_queue_mutex);
 }
 
 static void gpu_free_image_immediate(Image *ima)
diff --git a/source/blender/gpu/intern/gpu_viewport.c b/source/blender/gpu/intern/gpu_viewport.c
index 88b97ee2228..558b3f025a8 100644
--- a/source/blender/gpu/intern/gpu_viewport.c
+++ b/source/blender/gpu/intern/gpu_viewport.c
@@ -632,6 +632,15 @@ void GPU_viewport_free(GPUViewport *viewport)
   if (viewport->vmempool.passes != NULL) {
     BLI_mempool_destroy(viewport->vmempool.passes);
   }
+  if (viewport->vmempool.images != NULL) {
+    BLI_mempool_iter iter;
+    GPUTexture **tex;
+    BLI_mempool_iternew(viewport->vmempool.images, &iter);
+    while ((tex = BLI_mempool_iterstep(&iter))) {
+      GPU_texture_free(*tex);
+    }
+    BLI_mempool_destroy(viewport->vmempool.images);
+  }
 
   DRW_instance_data_list_free(viewport->idatalist);
   MEM_freeN(viewport->idatalist);