drm/shmem-helper: Pass GEM shmem object in public interfaces

Change all GEM SHMEM object functions that receive a GEM object
of type struct drm_gem_object to expect an object of type
struct drm_gem_shmem_object instead.

This change reduces the number of upcasts from struct drm_gem_object
by moving them into callers. The C compiler can now verify that the
GEM SHMEM functions are called with the correct type.

For consistency, the patch also renames drm_gem_shmem_free_object to
drm_gem_shmem_free. It further updates documentation for a number of
functions.

v3:
	* fix docs for drm_gem_shmem_object_free()
v2:
	* mention _object_ callbacks in docs (Daniel)

Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Acked-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: https://patchwork.freedesktop.org/patch/msgid/20211108093149.7226-4-tzimmermann@suse.de

1 files changed, 36 insertions, 47 deletions

diff --git a/drivers/gpu/drm/drm_gem_shmem_helper.c b/drivers/gpu/drm/drm_gem_shmem_helper.c
index 72ac263f20be..dfff073bf1e8 100644
--- a/drivers/gpu/drm/drm_gem_shmem_helper.c
+++ b/drivers/gpu/drm/drm_gem_shmem_helper.c
@@ -27,6 +27,11 @@
  *
  * This library provides helpers for GEM objects backed by shmem buffers
  * allocated using anonymous pageable memory.
+ *
+ * Functions that operate on the GEM object receive struct &drm_gem_shmem_object.
+ * For GEM callback helpers in struct &drm_gem_object functions, see likewise
+ * named functions with an _object_ infix (e.g., drm_gem_shmem_object_vmap() wraps
+ * drm_gem_shmem_vmap()). These helpers perform the necessary type conversion.
  */
 
 static const struct drm_gem_object_funcs drm_gem_shmem_funcs = {
@@ -117,15 +122,15 @@ struct drm_gem_shmem_object *drm_gem_shmem_create(struct drm_device *dev, size_t
 EXPORT_SYMBOL_GPL(drm_gem_shmem_create);
 
 /**
- * drm_gem_shmem_free_object - Free resources associated with a shmem GEM object
- * @obj: GEM object to free
+ * drm_gem_shmem_free - Free resources associated with a shmem GEM object
+ * @shmem: shmem GEM object to free
  *
  * This function cleans up the GEM object state and frees the memory used to
  * store the object itself.
  */
-void drm_gem_shmem_free_object(struct drm_gem_object *obj)
+void drm_gem_shmem_free(struct drm_gem_shmem_object *shmem)
 {
-	struct drm_gem_shmem_object *shmem = to_drm_gem_shmem_obj(obj);
+	struct drm_gem_object *obj = &shmem->base;
 
 	WARN_ON(shmem->vmap_use_count);
 
@@ -149,7 +154,7 @@ void drm_gem_shmem_free_object(struct drm_gem_object *obj)
 	mutex_destroy(&shmem->vmap_lock);
 	kfree(shmem);
 }
-EXPORT_SYMBOL_GPL(drm_gem_shmem_free_object);
+EXPORT_SYMBOL_GPL(drm_gem_shmem_free);
 
 static int drm_gem_shmem_get_pages_locked(struct drm_gem_shmem_object *shmem)
 {
@@ -244,7 +249,7 @@ EXPORT_SYMBOL(drm_gem_shmem_put_pages);
 
 /**
  * drm_gem_shmem_pin - Pin backing pages for a shmem GEM object
- * @obj: GEM object
+ * @shmem: shmem GEM object
  *
  * This function makes sure the backing pages are pinned in memory while the
  * buffer is exported.
@@ -252,10 +257,8 @@ EXPORT_SYMBOL(drm_gem_shmem_put_pages);
  * Returns:
  * 0 on success or a negative error code on failure.
  */
-int drm_gem_shmem_pin(struct drm_gem_object *obj)
+int drm_gem_shmem_pin(struct drm_gem_shmem_object *shmem)
 {
-	struct drm_gem_shmem_object *shmem = to_drm_gem_shmem_obj(obj);
-
 	WARN_ON(shmem->base.import_attach);
 
 	return drm_gem_shmem_get_pages(shmem);
@@ -264,15 +267,13 @@ EXPORT_SYMBOL(drm_gem_shmem_pin);
 
 /**
  * drm_gem_shmem_unpin - Unpin backing pages for a shmem GEM object
- * @obj: GEM object
+ * @shmem: shmem GEM object
  *
  * This function removes the requirement that the backing pages are pinned in
  * memory.
  */
-void drm_gem_shmem_unpin(struct drm_gem_object *obj)
+void drm_gem_shmem_unpin(struct drm_gem_shmem_object *shmem)
 {
-	struct drm_gem_shmem_object *shmem = to_drm_gem_shmem_obj(obj);
-
 	WARN_ON(shmem->base.import_attach);
 
 	drm_gem_shmem_put_pages(shmem);
@@ -346,9 +347,8 @@ err_zero_use:
  * Returns:
  * 0 on success or a negative error code on failure.
  */
-int drm_gem_shmem_vmap(struct drm_gem_object *obj, struct dma_buf_map *map)
+int drm_gem_shmem_vmap(struct drm_gem_shmem_object *shmem, struct dma_buf_map *map)
 {
-	struct drm_gem_shmem_object *shmem = to_drm_gem_shmem_obj(obj);
 	int ret;
 
 	ret = mutex_lock_interruptible(&shmem->vmap_lock);
@@ -394,10 +394,8 @@ static void drm_gem_shmem_vunmap_locked(struct drm_gem_shmem_object *shmem,
  * This function hides the differences between dma-buf imported and natively
  * allocated objects.
  */
-void drm_gem_shmem_vunmap(struct drm_gem_object *obj, struct dma_buf_map *map)
+void drm_gem_shmem_vunmap(struct drm_gem_shmem_object *shmem, struct dma_buf_map *map)
 {
-	struct drm_gem_shmem_object *shmem = to_drm_gem_shmem_obj(obj);
-
 	mutex_lock(&shmem->vmap_lock);
 	drm_gem_shmem_vunmap_locked(shmem, map);
 	mutex_unlock(&shmem->vmap_lock);
@@ -432,10 +430,8 @@ drm_gem_shmem_create_with_handle(struct drm_file *file_priv,
 /* Update madvise status, returns true if not purged, else
  * false or -errno.
  */
-int drm_gem_shmem_madvise(struct drm_gem_object *obj, int madv)
+int drm_gem_shmem_madvise(struct drm_gem_shmem_object *shmem, int madv)
 {
-	struct drm_gem_shmem_object *shmem = to_drm_gem_shmem_obj(obj);
-
 	mutex_lock(&shmem->pages_lock);
 
 	if (shmem->madv >= 0)
@@ -449,14 +445,14 @@ int drm_gem_shmem_madvise(struct drm_gem_object *obj, int madv)
 }
 EXPORT_SYMBOL(drm_gem_shmem_madvise);
 
-void drm_gem_shmem_purge_locked(struct drm_gem_object *obj)
+void drm_gem_shmem_purge_locked(struct drm_gem_shmem_object *shmem)
 {
+	struct drm_gem_object *obj = &shmem->base;
 	struct drm_device *dev = obj->dev;
-	struct drm_gem_shmem_object *shmem = to_drm_gem_shmem_obj(obj);
 
 	WARN_ON(!drm_gem_shmem_is_purgeable(shmem));
 
-	dma_unmap_sgtable(obj->dev->dev, shmem->sgt, DMA_BIDIRECTIONAL, 0);
+	dma_unmap_sgtable(dev->dev, shmem->sgt, DMA_BIDIRECTIONAL, 0);
 	sg_free_table(shmem->sgt);
 	kfree(shmem->sgt);
 	shmem->sgt = NULL;
@@ -475,18 +471,15 @@ void drm_gem_shmem_purge_locked(struct drm_gem_object *obj)
 	 */
 	shmem_truncate_range(file_inode(obj->filp), 0, (loff_t)-1);
 
-	invalidate_mapping_pages(file_inode(obj->filp)->i_mapping,
-			0, (loff_t)-1);
+	invalidate_mapping_pages(file_inode(obj->filp)->i_mapping, 0, (loff_t)-1);
 }
 EXPORT_SYMBOL(drm_gem_shmem_purge_locked);
 
-bool drm_gem_shmem_purge(struct drm_gem_object *obj)
+bool drm_gem_shmem_purge(struct drm_gem_shmem_object *shmem)
 {
-	struct drm_gem_shmem_object *shmem = to_drm_gem_shmem_obj(obj);
-
 	if (!mutex_trylock(&shmem->pages_lock))
 		return false;
-	drm_gem_shmem_purge_locked(obj);
+	drm_gem_shmem_purge_locked(shmem);
 	mutex_unlock(&shmem->pages_lock);
 
 	return true;
@@ -594,7 +587,7 @@ static const struct vm_operations_struct drm_gem_shmem_vm_ops = {
 
 /**
  * drm_gem_shmem_mmap - Memory-map a shmem GEM object
- * @obj: gem object
+ * @shmem: shmem GEM object
  * @vma: VMA for the area to be mapped
  *
  * This function implements an augmented version of the GEM DRM file mmap
@@ -603,9 +596,9 @@ static const struct vm_operations_struct drm_gem_shmem_vm_ops = {
  * Returns:
  * 0 on success or a negative error code on failure.
  */
-int drm_gem_shmem_mmap(struct drm_gem_object *obj, struct vm_area_struct *vma)
+int drm_gem_shmem_mmap(struct drm_gem_shmem_object *shmem, struct vm_area_struct *vma)
 {
-	struct drm_gem_shmem_object *shmem;
+	struct drm_gem_object *obj = &shmem->base;
 	int ret;
 
 	if (obj->import_attach) {
@@ -616,8 +609,6 @@ int drm_gem_shmem_mmap(struct drm_gem_object *obj, struct vm_area_struct *vma)
 		return dma_buf_mmap(obj->dma_buf, vma, 0);
 	}
 
-	shmem = to_drm_gem_shmem_obj(obj);
-
 	ret = drm_gem_shmem_get_pages(shmem);
 	if (ret) {
 		drm_gem_vm_close(vma);
@@ -636,15 +627,13 @@ EXPORT_SYMBOL_GPL(drm_gem_shmem_mmap);
 
 /**
  * drm_gem_shmem_print_info() - Print &drm_gem_shmem_object info for debugfs
+ * @shmem: shmem GEM object
  * @p: DRM printer
  * @indent: Tab indentation level
- * @obj: GEM object
  */
-void drm_gem_shmem_print_info(struct drm_printer *p, unsigned int indent,
-			      const struct drm_gem_object *obj)
+void drm_gem_shmem_print_info(const struct drm_gem_shmem_object *shmem,
+			      struct drm_printer *p, unsigned int indent)
 {
-	const struct drm_gem_shmem_object *shmem = to_drm_gem_shmem_obj(obj);
-
 	drm_printf_indent(p, indent, "pages_use_count=%u\n", shmem->pages_use_count);
 	drm_printf_indent(p, indent, "vmap_use_count=%u\n", shmem->vmap_use_count);
 	drm_printf_indent(p, indent, "vaddr=%p\n", shmem->vaddr);
@@ -654,7 +643,7 @@ EXPORT_SYMBOL(drm_gem_shmem_print_info);
 /**
  * drm_gem_shmem_get_sg_table - Provide a scatter/gather table of pinned
  *                              pages for a shmem GEM object
- * @obj: GEM object
+ * @shmem: shmem GEM object
  *
  * This function exports a scatter/gather table suitable for PRIME usage by
  * calling the standard DMA mapping API.
@@ -665,9 +654,9 @@ EXPORT_SYMBOL(drm_gem_shmem_print_info);
  * Returns:
  * A pointer to the scatter/gather table of pinned pages or NULL on failure.
  */
-struct sg_table *drm_gem_shmem_get_sg_table(struct drm_gem_object *obj)
+struct sg_table *drm_gem_shmem_get_sg_table(struct drm_gem_shmem_object *shmem)
 {
-	struct drm_gem_shmem_object *shmem = to_drm_gem_shmem_obj(obj);
+	struct drm_gem_object *obj = &shmem->base;
 
 	WARN_ON(shmem->base.import_attach);
 
@@ -678,7 +667,7 @@ EXPORT_SYMBOL_GPL(drm_gem_shmem_get_sg_table);
 /**
  * drm_gem_shmem_get_pages_sgt - Pin pages, dma map them, and return a
  *				 scatter/gather table for a shmem GEM object.
- * @obj: GEM object
+ * @shmem: shmem GEM object
  *
  * This function returns a scatter/gather table suitable for driver usage. If
  * the sg table doesn't exist, the pages are pinned, dma-mapped, and a sg
@@ -691,10 +680,10 @@ EXPORT_SYMBOL_GPL(drm_gem_shmem_get_sg_table);
  * Returns:
  * A pointer to the scatter/gather table of pinned pages or errno on failure.
  */
-struct sg_table *drm_gem_shmem_get_pages_sgt(struct drm_gem_object *obj)
+struct sg_table *drm_gem_shmem_get_pages_sgt(struct drm_gem_shmem_object *shmem)
 {
+	struct drm_gem_object *obj = &shmem->base;
 	int ret;
-	struct drm_gem_shmem_object *shmem = to_drm_gem_shmem_obj(obj);
 	struct sg_table *sgt;
 
 	if (shmem->sgt)
@@ -706,7 +695,7 @@ struct sg_table *drm_gem_shmem_get_pages_sgt(struct drm_gem_object *obj)
 	if (ret)
 		return ERR_PTR(ret);
 
-	sgt = drm_gem_shmem_get_sg_table(&shmem->base);
+	sgt = drm_gem_shmem_get_sg_table(shmem);
 	if (IS_ERR(sgt)) {
 		ret = PTR_ERR(sgt);
 		goto err_put_pages;