drm/ttm: add common accounting to the resource mgr v3

It makes sense to have this in the common manager for debugging and
accounting of how much resources are used.

v2: cleanup kerneldoc a bit
v3: drop the atomic, update counter under lock instead
Signed-off-by: Christian König <christian.koenig@amd.com>
Reviewed-by: Huang Rui <ray.huang@amd.com> (v1)
Reviewed-by: Matthew Auld <matthew.auld@intel.com>
Tested-by: Bas Nieuwenhuizen <bas@basnieuwenhuizen.nl>
Link: https://patchwork.freedesktop.org/patch/msgid/20220214093439.2989-2-christian.koenig@amd.com

drivers/gpu/drm/ttm/ttm_resource.c

@@ -41,6 +41,8 @@ void ttm_resource_init(struct ttm_buffer_object *bo,
                        const struct ttm_place *place,
                        struct ttm_resource *res)
 {
+	struct ttm_resource_manager *man;
+
 	res->start = 0;
 	res->num_pages = PFN_UP(bo->base.size);
 	res->mem_type = place->mem_type;
@@ -50,6 +52,11 @@ void ttm_resource_init(struct ttm_buffer_object *bo,
 	res->bus.is_iomem = false;
 	res->bus.caching = ttm_cached;
 	res->bo = bo;
+
+	man = ttm_manager_type(bo->bdev, place->mem_type);
+	spin_lock(&bo->bdev->lru_lock);
+	man->usage += bo->base.size;
+	spin_unlock(&bo->bdev->lru_lock);
 }
 EXPORT_SYMBOL(ttm_resource_init);
 
@@ -65,6 +72,9 @@ EXPORT_SYMBOL(ttm_resource_init);
 void ttm_resource_fini(struct ttm_resource_manager *man,
 		       struct ttm_resource *res)
 {
+	spin_lock(&man->bdev->lru_lock);
+	man->usage -= res->bo->base.size;
+	spin_unlock(&man->bdev->lru_lock);
 }
 EXPORT_SYMBOL(ttm_resource_fini);
 
@@ -166,6 +176,7 @@ void ttm_resource_manager_init(struct ttm_resource_manager *man,
 	spin_lock_init(&man->move_lock);
 	man->bdev = bdev;
 	man->size = size;
+	man->usage = 0;
 
 	for (i = 0; i < TTM_MAX_BO_PRIORITY; ++i)
 		INIT_LIST_HEAD(&man->lru[i]);
@@ -226,6 +237,24 @@ int ttm_resource_manager_evict_all(struct ttm_device *bdev,
 }
 EXPORT_SYMBOL(ttm_resource_manager_evict_all);
 
+/**
+ * ttm_resource_manager_usage
+ *
+ * @man: A memory manager object.
+ *
+ * Return how many resources are currently used.
+ */
+uint64_t ttm_resource_manager_usage(struct ttm_resource_manager *man)
+{
+	uint64_t usage;
+
+	spin_lock(&man->bdev->lru_lock);
+	usage = man->usage;
+	spin_unlock(&man->bdev->lru_lock);
+	return usage;
+}
+EXPORT_SYMBOL(ttm_resource_manager_usage);
+
 /**
  * ttm_resource_manager_debug
  *
@@ -238,6 +267,7 @@ void ttm_resource_manager_debug(struct ttm_resource_manager *man,
 	drm_printf(p, "  use_type: %d\n", man->use_type);
 	drm_printf(p, "  use_tt: %d\n", man->use_tt);
 	drm_printf(p, "  size: %llu\n", man->size);
+	drm_printf(p, "  usage: %llu\n", ttm_resource_manager_usage(man));
 	if (man->func->debug)
 		man->func->debug(man, p);
 }

include/drm/ttm/ttm_resource.h

@@ -27,6 +27,7 @@
 
 #include <linux/types.h>
 #include <linux/mutex.h>
+#include <linux/atomic.h>
 #include <linux/dma-buf-map.h>
 #include <linux/dma-fence.h>
 #include <drm/drm_print.h>
@@ -130,10 +131,15 @@ struct ttm_resource_manager {
 	struct dma_fence *move;
 
 	/*
-	 * Protected by the global->lru_lock.
+	 * Protected by the bdev->lru_lock.
 	 */
-
 	struct list_head lru[TTM_MAX_BO_PRIORITY];
+
+	/**
+	 * @usage: How much of the resources are used, protected by the
+	 * bdev->lru_lock.
+	 */
+	uint64_t usage;
 };
 
 /**
@@ -283,6 +289,7 @@ void ttm_resource_manager_init(struct ttm_resource_manager *man,
 int ttm_resource_manager_evict_all(struct ttm_device *bdev,
 				   struct ttm_resource_manager *man);
 
+uint64_t ttm_resource_manager_usage(struct ttm_resource_manager *man);
 void ttm_resource_manager_debug(struct ttm_resource_manager *man,
 				struct drm_printer *p);