[PATCH RFC 13/18] drm/gem: Add a flag to control whether objects can be exported

[Asahi Lina]

Drivers may want to support driver-private objects, which cannot be
shared. This allows them to share a single lock and enables other
optimizations.

Add an `exportable` field to drm_gem_object, which blocks PRIME export
if set to false. It is initialized to true in
drm_gem_private_object_init.

Signed-off-by: Asahi Lina <lina at asahilina.net>
---
 drivers/gpu/drm/drm_gem.c   | 1 +
 drivers/gpu/drm/drm_prime.c | 5 +++++
 include/drm/drm_gem.h       | 8 ++++++++
 3 files changed, 14 insertions(+)

diff --git a/drivers/gpu/drm/drm_gem.c b/drivers/gpu/drm/drm_gem.c
index 7a3cb08dc942..152ad9295a8d 100644
--- a/drivers/gpu/drm/drm_gem.c
+++ b/drivers/gpu/drm/drm_gem.c
@@ -166,6 +166,7 @@ void drm_gem_private_object_init(struct drm_device *dev,
 
 	drm_vma_node_reset(&obj->vma_node);
 	INIT_LIST_HEAD(&obj->lru_node);
+	obj->exportable = true;
 }
 EXPORT_SYMBOL(drm_gem_private_object_init);
 
diff --git a/drivers/gpu/drm/drm_prime.c b/drivers/gpu/drm/drm_prime.c
index f924b8b4ab6b..9d2dd982580e 100644
--- a/drivers/gpu/drm/drm_prime.c
+++ b/drivers/gpu/drm/drm_prime.c
@@ -391,6 +391,11 @@ static struct dma_buf *export_and_register_object(struct drm_device *dev,
 		return dmabuf;
 	}
 
+	if (!obj->exportable) {
+		dmabuf = ERR_PTR(-EINVAL);
+		return dmabuf;
+	}
+
 	if (obj->funcs && obj->funcs->export)
 		dmabuf = obj->funcs->export(obj, flags);
 	else
diff --git a/include/drm/drm_gem.h b/include/drm/drm_gem.h
index 772a4adf5287..852dec3cf763 100644
--- a/include/drm/drm_gem.h
+++ b/include/drm/drm_gem.h
@@ -361,6 +361,14 @@ struct drm_gem_object {
 	 * The current LRU list that the GEM object is on.
 	 */
 	struct drm_gem_lru *lru;
+
+	/**
+	 * @exportable:
+	 *
+	 * Whether this GEM object can be exported via the drm_gem_object_funcs->export
+	 * callback. Defaults to true.
+	 */
+	bool exportable;
 };
 
 /**

-- 
2.35.1