drm/udl: handle page mapping in dmabuf export.

Fixes dmabuf export failure with -E_NOMEM when the page is not mapped.
Signed-off-by: Haixia Shi <hshi@chromium.org>
Reviewed-by: Stéphane Marchesin <marcheu@chromium.org>
Signed-off-by: Dave Airlie <airlied@redhat.com>

drivers/gpu/drm/udl/udl_dmabuf.c

@@ -90,8 +90,11 @@ static struct sg_table *udl_map_dma_buf(struct dma_buf_attachment *attach,
 		return &udl_attach->sgt;
 
 	if (!obj->pages) {
-		DRM_ERROR("pages is null.\n");
-		return ERR_PTR(-ENOMEM);
+		ret = udl_gem_get_pages(obj);
+		if (ret) {
+			DRM_ERROR("failed to map pages.\n");
+			return ERR_PTR(ret);
+		}
 	}
 
 	page_count = obj->base.size / PAGE_SIZE;

drivers/gpu/drm/udl/udl_drv.h

@@ -129,6 +129,8 @@ struct dma_buf *udl_gem_prime_export(struct drm_device *dev,
 struct drm_gem_object *udl_gem_prime_import(struct drm_device *dev,
 				struct dma_buf *dma_buf);
 
+int udl_gem_get_pages(struct udl_gem_object *obj);
+void udl_gem_put_pages(struct udl_gem_object *obj);
 int udl_gem_vmap(struct udl_gem_object *obj);
 void udl_gem_vunmap(struct udl_gem_object *obj);
 int udl_drm_gem_mmap(struct file *filp, struct vm_area_struct *vma);

drivers/gpu/drm/udl/udl_gem.c

@@ -127,7 +127,7 @@ int udl_gem_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
 	}
 }
 
-static int udl_gem_get_pages(struct udl_gem_object *obj)
+int udl_gem_get_pages(struct udl_gem_object *obj)
 {
 	struct page **pages;
 
@@ -143,7 +143,7 @@ static int udl_gem_get_pages(struct udl_gem_object *obj)
 	return 0;
 }
 
-static void udl_gem_put_pages(struct udl_gem_object *obj)
+void udl_gem_put_pages(struct udl_gem_object *obj)
 {
 	if (obj->base.import_attach) {
 		drm_free_large(obj->pages);