[PATCH] drm: Wrap direct calls to driver->gem_free_object from CMA

[Chris Wilson]

Since the introduction of (struct_mutex) lockless GEM bo freeing, there
are a pair of driver vfuncs for freeing the GEM bo, of which the driver
may choose to only implement driver->gem_object_free_unlocked (and so
avoid taking the struct_mutex along the free path). However, the CMA GEM
helpers were still calling driver->gem_free_object directly, now NULL,
and promptly dying on the fancy new lockless drivers. Oops.

Robert Foss bisected this to b82caafcf2303 (drm/vc4: Use lockless gem BO
free callback) on his vc4 device, but that just serves as an enabler for
9f0ba539d13ae (drm/gem: support BO freeing without dev->struct_mutex).

Reported-by: Robert Foss <robert.foss at collabora.com>
Fixes: 9f0ba539d13ae (drm/gem: support BO freeing without dev->struct_mutex)
Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
Cc: Robert Foss <robert.foss at collabora.com>
Cc: Daniel Vetter <daniel.vetter at intel.com>
Cc: Eric Anholt <eric at anholt.net>
Cc: Alex Deucher <alexdeucher at gmail.com>
Cc: Lucas Stach <l.stach at pengutronix.de>
Cc: stable at vger.kernel.org
---
 drivers/gpu/drm/drm_fb_cma_helper.c  |  2 +-
 drivers/gpu/drm/drm_gem_cma_helper.c | 12 +++---------
 2 files changed, 4 insertions(+), 10 deletions(-)

diff --git a/drivers/gpu/drm/drm_fb_cma_helper.c b/drivers/gpu/drm/drm_fb_cma_helper.c
index 172cafe11c71..5075fae3c4e2 100644
--- a/drivers/gpu/drm/drm_fb_cma_helper.c
+++ b/drivers/gpu/drm/drm_fb_cma_helper.c
@@ -445,7 +445,7 @@ err_cma_destroy:
 err_fb_info_destroy:
 	drm_fb_helper_release_fbi(helper);
 err_gem_free_object:
-	dev->driver->gem_free_object(&obj->base);
+	drm_gem_object_unreference_unlocked(&obj->base);
 	return ret;
 }
 EXPORT_SYMBOL(drm_fbdev_cma_create_with_funcs);
diff --git a/drivers/gpu/drm/drm_gem_cma_helper.c b/drivers/gpu/drm/drm_gem_cma_helper.c
index e1ab008b3f08..1d6c335584ec 100644
--- a/drivers/gpu/drm/drm_gem_cma_helper.c
+++ b/drivers/gpu/drm/drm_gem_cma_helper.c
@@ -121,7 +121,7 @@ struct drm_gem_cma_object *drm_gem_cma_create(struct drm_device *drm,
 	return cma_obj;
 
 error:
-	drm->driver->gem_free_object(&cma_obj->base);
+	drm_gem_object_unreference_unlocked(&cma_obj->base);
 	return ERR_PTR(ret);
 }
 EXPORT_SYMBOL_GPL(drm_gem_cma_create);
@@ -162,18 +162,12 @@ drm_gem_cma_create_with_handle(struct drm_file *file_priv,
 	 * and handle has the id what user can see.
 	 */
 	ret = drm_gem_handle_create(file_priv, gem_obj, handle);
-	if (ret)
-		goto err_handle_create;
-
 	/* drop reference from allocate - handle holds it now. */
 	drm_gem_object_unreference_unlocked(gem_obj);
+	if (ret)
+		return ERR_PTR(ret);
 
 	return cma_obj;
-
-err_handle_create:
-	drm->driver->gem_free_object(gem_obj);
-
-	return ERR_PTR(ret);
 }
 
 /**
-- 
2.8.1