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.")
Reviewed-by: Boris Brezillon <boris.brezillon@free-electrons.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20170301185602.6873-2-eric@anholt.net

diff --git a/drivers/gpu/drm/vc4/vc4_bo.c b/drivers/gpu/drm/vc4/vc4_bo.c
index e5c7aa935b4b84379cc5fdddb59d6b666540f38f..af29432a6471a1063da5e0611430052c754a8a16 100644 (file)
--- a/drivers/gpu/drm/vc4/vc4_bo.c
+++ b/drivers/gpu/drm/vc4/vc4_bo.c
@@ -317,6 +317,14 @@ 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);