drm/ttm: further cleanup ttm_mem_reg handling

Stop touching the backend private pointer alltogether and
make sure we never put the same mem twice by.
Signed-off-by: Christian König <christian.koenig@amd.com>
Reviewed-by: Madhav Chauhan <madhav.chauhan@amd.com>
Link: https://patchwork.freedesktop.org/patch/375613/

drivers/gpu/drm/ttm/ttm_bo.c

@@ -312,7 +312,6 @@ static int ttm_bo_handle_move_mem(struct ttm_buffer_object *bo,
 			if (bdev->driver->move_notify)
 				bdev->driver->move_notify(bo, evict, mem);
 			bo->mem = *mem;
-			mem->mm_node = NULL;
 			goto moved;
 		}
 	}
@@ -616,7 +615,6 @@ static void ttm_bo_release(struct kref *kref)
 	ttm_bo_cleanup_memtype_use(bo);
 	dma_resv_unlock(bo->base.resv);
 
-	BUG_ON(bo->mem.mm_node != NULL);
 	atomic_dec(&ttm_bo_glob.bo_count);
 	dma_fence_put(bo->moving);
 	if (!ttm_bo_uses_embedded_gem_object(bo))
@@ -843,12 +841,29 @@ static int ttm_mem_evict_first(struct ttm_bo_device *bdev,
 	return ret;
 }
 
+static int ttm_bo_mem_get(struct ttm_buffer_object *bo,
+			  const struct ttm_place *place,
+			  struct ttm_mem_reg *mem)
+{
+	struct ttm_mem_type_manager *man = &bo->bdev->man[mem->mem_type];
+
+	mem->mm_node = NULL;
+	if (!man->func || !man->func->get_node)
+		return 0;
+
+	return man->func->get_node(man, bo, place, mem);
+}
+
 void ttm_bo_mem_put(struct ttm_buffer_object *bo, struct ttm_mem_reg *mem)
 {
 	struct ttm_mem_type_manager *man = &bo->bdev->man[mem->mem_type];
 
-	if (mem->mm_node)
-		(*man->func->put_node)(man, mem);
+	if (!man->func || !man->func->put_node)
+		return;
+
+	man->func->put_node(man, mem);
+	mem->mm_node = NULL;
+	mem->mem_type = TTM_PL_SYSTEM;
 }
 EXPORT_SYMBOL(ttm_bo_mem_put);
 
@@ -902,7 +917,7 @@ static int ttm_bo_mem_force_space(struct ttm_buffer_object *bo,
 
 	ticket = dma_resv_locking_ctx(bo->base.resv);
 	do {
-		ret = (*man->func->get_node)(man, bo, place, mem);
+		ret = ttm_bo_mem_get(bo, place, mem);
 		if (likely(!ret))
 			break;
 		if (unlikely(ret != -ENOSPC))
@@ -1032,7 +1047,6 @@ int ttm_bo_mem_space(struct ttm_buffer_object *bo,
 	if (unlikely(ret))
 		return ret;
 
-	mem->mm_node = NULL;
 	for (i = 0; i < placement->num_placement; ++i) {
 		const struct ttm_place *place = &placement->placement[i];
 		struct ttm_mem_type_manager *man;
@@ -1044,20 +1058,16 @@ int ttm_bo_mem_space(struct ttm_buffer_object *bo,
 			goto error;
 
 		type_found = true;
-		mem->mm_node = NULL;
-		if (mem->mem_type == TTM_PL_SYSTEM)
-			return 0;
-
-		man = &bdev->man[mem->mem_type];
-		ret = (*man->func->get_node)(man, bo, place, mem);
+		ret = ttm_bo_mem_get(bo, place, mem);
 		if (ret == -ENOSPC)
 			continue;
 		if (unlikely(ret))
 			goto error;
 
+		man = &bdev->man[mem->mem_type];
 		ret = ttm_bo_add_move_fence(bo, man, mem, ctx->no_wait_gpu);
 		if (unlikely(ret)) {
-			(*man->func->put_node)(man, mem);
+			ttm_bo_mem_put(bo, mem);
 			if (ret == -EBUSY)
 				continue;
 
@@ -1076,12 +1086,8 @@ int ttm_bo_mem_space(struct ttm_buffer_object *bo,
 			goto error;
 
 		type_found = true;
-		mem->mm_node = NULL;
-		if (mem->mem_type == TTM_PL_SYSTEM)
-			return 0;
-
 		ret = ttm_bo_mem_force_space(bo, place, mem, ctx);
-		if (ret == 0 && mem->mm_node)
+		if (likely(!ret))
 			return 0;
 
 		if (ret && ret != -EBUSY)
@@ -1129,7 +1135,7 @@ static int ttm_bo_move_buffer(struct ttm_buffer_object *bo,
 		goto out_unlock;
 	ret = ttm_bo_handle_move_mem(bo, &mem, false, ctx);
 out_unlock:
-	if (ret && mem.mm_node)
+	if (ret)
 		ttm_bo_mem_put(bo, &mem);
 	return ret;
 }
@@ -1144,7 +1150,7 @@ static bool ttm_bo_places_compat(const struct ttm_place *places,
 	for (i = 0; i < num_placement; i++) {
 		const struct ttm_place *heap = &places[i];
 
-		if (mem->mm_node && (mem->start < heap->fpfn ||
+		if ((mem->start < heap->fpfn ||
 		     (heap->lpfn != 0 && (mem->start + mem->num_pages) > heap->lpfn)))
 			continue;
 

include/drm/ttm/ttm_bo_driver.h

@@ -564,8 +564,6 @@ int ttm_bo_mem_space(struct ttm_buffer_object *bo,
 		     struct ttm_operation_ctx *ctx);
 
 void ttm_bo_mem_put(struct ttm_buffer_object *bo, struct ttm_mem_reg *mem);
-void ttm_bo_mem_put_locked(struct ttm_buffer_object *bo,
-			   struct ttm_mem_reg *mem);
 
 int ttm_bo_device_release(struct ttm_bo_device *bdev);