drm/shmem-helpers: Simplify dma-buf importing

- Ditch the ->pages array
- Make it a private gem bo, which means no shmem object, which means
  fireworks if anyone calls drm_gem_object_get_pages. But we've just
  made sure that's all covered.

v2: Rebase

v3: I forgot to remove the page_count mangling from the free path too.
Noticed by Boris while testing.

Cc: Boris Brezillon <boris.brezillon@collabora.com>
Tested-by: Boris Brezillon <boris.brezillon@collabora.com>
Acked-by: Thomas Zimmermann <tzimmermann@suse.de>
Cc: Gerd Hoffmann <kraxel@redhat.com>
Cc: Rob Herring <robh@kernel.org>
Cc: Noralf Trønnes <noralf@tronnes.org>
Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200529140542.2103713-1-daniel.vetter@ffwll.ch

diff --git a/drivers/gpu/drm/drm_gem_shmem_helper.c b/drivers/gpu/drm/drm_gem_shmem_helper.c
index 06cee8e97d27a55833f45afc5b912905df0d3199..f750063968efc01356bc6998282212bc4a42c178 100644 (file)
--- a/drivers/gpu/drm/drm_gem_shmem_helper.c
+++ b/drivers/gpu/drm/drm_gem_shmem_helper.c
@@ -35,22 +35,12 @@ static const struct drm_gem_object_funcs drm_gem_shmem_funcs = {
        .mmap = drm_gem_shmem_mmap,
 };
 
-/**
- * drm_gem_shmem_create - Allocate an object with the given size
- * @dev: DRM device
- * @size: Size of the object to allocate
- *
- * This function creates a shmem GEM object.
- *
- * Returns:
- * A struct drm_gem_shmem_object * on success or an ERR_PTR()-encoded negative
- * error code on failure.
- */
-struct drm_gem_shmem_object *drm_gem_shmem_create(struct drm_device *dev, size_t size)
+static struct drm_gem_shmem_object *
+__drm_gem_shmem_create(struct drm_device *dev, size_t size, bool private)
 {
        struct drm_gem_shmem_object *shmem;
        struct drm_gem_object *obj;
-       int ret;
+       int ret = 0;
 
        size = PAGE_ALIGN(size);
 
@@ -64,7 +54,10 @@ struct drm_gem_shmem_object *drm_gem_shmem_create(struct drm_device *dev, size_t
        if (!obj->funcs)
                obj->funcs = &drm_gem_shmem_funcs;
 
-       ret = drm_gem_object_init(dev, obj, size);
+       if (private)
+               drm_gem_private_object_init(dev, obj, size);
+       else
+               ret = drm_gem_object_init(dev, obj, size);
        if (ret)
                goto err_free;
 
@@ -96,6 +89,21 @@ err_free:
 
        return ERR_PTR(ret);
 }
+/**
+ * drm_gem_shmem_create - Allocate an object with the given size
+ * @dev: DRM device
+ * @size: Size of the object to allocate
+ *
+ * This function creates a shmem GEM object.
+ *
+ * Returns:
+ * A struct drm_gem_shmem_object * on success or an ERR_PTR()-encoded negative
+ * error code on failure.
+ */
+struct drm_gem_shmem_object *drm_gem_shmem_create(struct drm_device *dev, size_t size)
+{
+       return __drm_gem_shmem_create(dev, size, false);
+}
 EXPORT_SYMBOL_GPL(drm_gem_shmem_create);
 
 /**
@@ -113,9 +121,7 @@ void drm_gem_shmem_free_object(struct drm_gem_object *obj)
        WARN_ON(shmem->vmap_use_count);
 
        if (obj->import_attach) {
-               shmem->pages_use_count--;
                drm_prime_gem_destroy(obj, shmem->sgt);
-               kvfree(shmem->pages);
        } else {
                if (shmem->sgt) {
                        dma_unmap_sg(obj->dev->dev, shmem->sgt->sgl,
@@ -371,7 +377,7 @@ drm_gem_shmem_create_with_handle(struct drm_file *file_priv,
        struct drm_gem_shmem_object *shmem;
        int ret;
 
-       shmem = drm_gem_shmem_create(dev, size);
+       shmem = __drm_gem_shmem_create(dev, size, true);
        if (IS_ERR(shmem))
                return shmem;
 
@@ -695,36 +701,16 @@ drm_gem_shmem_prime_import_sg_table(struct drm_device *dev,
                                    struct sg_table *sgt)
 {
        size_t size = PAGE_ALIGN(attach->dmabuf->size);
-       size_t npages = size >> PAGE_SHIFT;
        struct drm_gem_shmem_object *shmem;
-       int ret;
 
        shmem = drm_gem_shmem_create(dev, size);
        if (IS_ERR(shmem))
                return ERR_CAST(shmem);
 
-       shmem->pages = kvmalloc_array(npages, sizeof(struct page *), GFP_KERNEL);
-       if (!shmem->pages) {
-               ret = -ENOMEM;
-               goto err_free_gem;
-       }
-
-       ret = drm_prime_sg_to_page_addr_arrays(sgt, shmem->pages, NULL, npages);
-       if (ret < 0)
-               goto err_free_array;
-
        shmem->sgt = sgt;
-       shmem->pages_use_count = 1; /* Permanently pinned from our point of view */
 
        DRM_DEBUG_PRIME("size = %zu\n", size);
 
        return &shmem->base;
-
-err_free_array:
-       kvfree(shmem->pages);
-err_free_gem:
-       drm_gem_object_put(&shmem->base);
-
-       return ERR_PTR(ret);
 }
 EXPORT_SYMBOL_GPL(drm_gem_shmem_prime_import_sg_table);