[PATCH 1/3] drm/ttm: split BO structure initialization into a separate function

[Nicolai Hähnle]

From: Nicolai Hähnle <nicolai.haehnle at amd.com>

Allow callers to opt out of calling ttm_bo_validate immediately. This
allows more flexibility in how locking of the reservation object is
done, which is needed to fix a locking bug (destroy locked mutex)
in amdgpu.

Signed-off-by: Nicolai Hähnle <nicolai.haehnle at amd.com>
---
 drivers/gpu/drm/ttm/ttm_bo.c | 62 +++++++++++++++++++++++++++++---------------
 include/drm/ttm/ttm_bo_api.h | 45 ++++++++++++++++++++++++++++++++
 2 files changed, 86 insertions(+), 21 deletions(-)

diff --git a/drivers/gpu/drm/ttm/ttm_bo.c b/drivers/gpu/drm/ttm/ttm_bo.c
index 76bee42..ce4c0f5 100644
--- a/drivers/gpu/drm/ttm/ttm_bo.c
+++ b/drivers/gpu/drm/ttm/ttm_bo.c
@@ -1120,41 +1120,30 @@ int ttm_bo_validate(struct ttm_buffer_object *bo,
 }
 EXPORT_SYMBOL(ttm_bo_validate);
 
-int ttm_bo_init(struct ttm_bo_device *bdev,
-		struct ttm_buffer_object *bo,
-		unsigned long size,
-		enum ttm_bo_type type,
-		struct ttm_placement *placement,
-		uint32_t page_alignment,
-		bool interruptible,
-		struct file *persistent_swap_storage,
-		size_t acc_size,
-		struct sg_table *sg,
-		struct reservation_object *resv,
-		void (*destroy) (struct ttm_buffer_object *))
+int ttm_bo_init_top(struct ttm_bo_device *bdev,
+		    struct ttm_buffer_object *bo,
+		    unsigned long size,
+		    enum ttm_bo_type type,
+		    uint32_t page_alignment,
+		    struct file *persistent_swap_storage,
+		    size_t acc_size,
+		    struct sg_table *sg,
+		    struct reservation_object *resv,
+		    void (*destroy) (struct ttm_buffer_object *))
 {
 	int ret = 0;
 	unsigned long num_pages;
 	struct ttm_mem_global *mem_glob = bdev->glob->mem_glob;
-	bool locked;
 
 	ret = ttm_mem_global_alloc(mem_glob, acc_size, false, false);
 	if (ret) {
 		pr_err("Out of kernel memory\n");
-		if (destroy)
-			(*destroy)(bo);
-		else
-			kfree(bo);
 		return -ENOMEM;
 	}
 
 	num_pages = (size + PAGE_SIZE - 1) >> PAGE_SHIFT;
 	if (num_pages == 0) {
 		pr_err("Illegal buffer object size\n");
-		if (destroy)
-			(*destroy)(bo);
-		else
-			kfree(bo);
 		ttm_mem_global_free(mem_glob, acc_size);
 		return -EINVAL;
 	}
@@ -1204,6 +1193,37 @@ int ttm_bo_init(struct ttm_bo_device *bdev,
 		ret = drm_vma_offset_add(&bdev->vma_manager, &bo->vma_node,
 					 bo->mem.num_pages);
 
+	return ret;
+}
+EXPORT_SYMBOL(ttm_bo_init_top);
+
+int ttm_bo_init(struct ttm_bo_device *bdev,
+		struct ttm_buffer_object *bo,
+		unsigned long size,
+		enum ttm_bo_type type,
+		struct ttm_placement *placement,
+		uint32_t page_alignment,
+		bool interruptible,
+		struct file *persistent_swap_storage,
+		size_t acc_size,
+		struct sg_table *sg,
+		struct reservation_object *resv,
+		void (*destroy) (struct ttm_buffer_object *))
+{
+	bool locked;
+	int ret;
+
+	ret = ttm_bo_init_top(bdev, bo, size, type, page_alignment,
+			      persistent_swap_storage, acc_size, sg, resv,
+			      destroy);
+	if (ret) {
+		if (destroy)
+			(*destroy)(bo);
+		else
+			kfree(bo);
+		return ret;
+	}
+
 	/* passed reservation objects should already be locked,
 	 * since otherwise lockdep will be angered in radeon.
 	 */
diff --git a/include/drm/ttm/ttm_bo_api.h b/include/drm/ttm/ttm_bo_api.h
index f195899..d44b8e4 100644
--- a/include/drm/ttm/ttm_bo_api.h
+++ b/include/drm/ttm/ttm_bo_api.h
@@ -453,6 +453,51 @@ size_t ttm_bo_dma_acc_size(struct ttm_bo_device *bdev,
 			   unsigned struct_size);
 
 /**
+ * ttm_bo_init_top
+ *
+ * @bdev: Pointer to a ttm_bo_device struct.
+ * @bo: Pointer to a ttm_buffer_object to be initialized.
+ * @size: Requested size of buffer object.
+ * @type: Requested type of buffer object.
+ * @flags: Initial placement flags.
+ * @page_alignment: Data alignment in pages.
+ * @persistent_swap_storage: Usually the swap storage is deleted for buffers
+ * pinned in physical memory. If this behaviour is not desired, this member
+ * holds a pointer to a persistent shmem object. Typically, this would
+ * point to the shmem object backing a GEM object if TTM is used to back a
+ * GEM user interface.
+ * @acc_size: Accounted size for this object.
+ * @resv: Pointer to a reservation_object, or NULL to let ttm allocate one.
+ * @destroy: Destroy function. Use NULL for kfree().
+ *
+ * This function initializes a pre-allocated struct ttm_buffer_object.
+ * As this object may be part of a larger structure, this function,
+ * together with the @destroy function,
+ * enables driver-specific objects derived from a ttm_buffer_object.
+ *
+ * Unlike ttm_bo_init, @bo is not validated, and when an error is returned,
+ * the caller is responsible for freeing @bo (but the setup performed by
+ * ttm_bo_init_top itself is cleaned up).
+ *
+ * On successful return, the object kref and list_kref are set to 1.
+ *
+ * Returns
+ * -ENOMEM: Out of memory.
+ * -EINVAL: Invalid buffer size.
+ */
+
+extern int ttm_bo_init_top(struct ttm_bo_device *bdev,
+			   struct ttm_buffer_object *bo,
+			   unsigned long size,
+			   enum ttm_bo_type type,
+			   uint32_t page_alignment,
+			   struct file *persistent_swap_storage,
+			   size_t acc_size,
+			   struct sg_table *sg,
+			   struct reservation_object *resv,
+			   void (*destroy) (struct ttm_buffer_object *));
+
+/**
  * ttm_bo_init
  *
  * @bdev: Pointer to a ttm_bo_device struct.
-- 
2.9.3