drm/vc4: Fix OOPSes from trying to cache a partially constructed BO.

If a CMA allocation failed, the partially constructed BO would be
unreferenced through the normal path, and we might choose to put it in
the BO cache.  If we then reused it before it expired from the cache,
the kernel would OOPS.

Signed-off-by: Eric Anholt <eric@anholt.net>
Fixes: c826a6e10644 ("drm/vc4: Add a BO cache.")
Signed-off-by: Tim Gardner <tim.gardner@canonical.com>

diff --git a/drivers/gpu/drm/vc4/vc4_bo.c b/drivers/gpu/drm/vc4/vc4_bo.c
index 5ec14f25625dde6fd61e10415092fa25527cc151..fd83a28076564b9ea5cf0f2ba29b884ee3c5af43 100644 (file)
--- a/drivers/gpu/drm/vc4/vc4_bo.c
+++ b/drivers/gpu/drm/vc4/vc4_bo.c
@@ -314,6 +314,14 @@ void vc4_free_object(struct drm_gem_object *gem_bo)
                goto out;
        }
 
+       /* If this object was partially constructed but CMA allocation
+        * had failed, just free it.
+        */
+       if (!bo->base.vaddr) {
+               vc4_bo_destroy(bo);
+               goto out;
+       }
+
        cache_list = vc4_get_cache_list_for_size(dev, gem_bo->size);
        if (!cache_list) {
                vc4_bo_destroy(bo);