[PATCH 36/55] drm/i915: Kill drop_pages()

Chris Wilson
2016-07-25T17:39:34Z

The drop_pages() function is a dangerous trap in that it can release the
passed in object pointer and so unless the caller is aware, it can
easily trick us into using the stale object afterwards. Move it into its
solitary callsite where we know it is safe.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
---
drivers/gpu/drm/i915/i915_gem.c | 20 +++++---------------
1 file changed, 5 insertions(+), 15 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
index 9169f5f3d20c..bcc05dd2be5a 100644
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -306,20 +306,6 @@ i915_gem_object_unbind(struct drm_i915_gem_object *obj)
return ret;
}

-static int
-drop_pages(struct drm_i915_gem_object *obj)
-{
- int ret;
-
- i915_gem_object_get(obj);
- ret = i915_gem_object_unbind(obj);
- if (ret == 0)
- ret = i915_gem_object_put_pages(obj);
- i915_gem_object_put(obj);
-
- return ret;
-}
-
int
i915_gem_object_attach_phys(struct drm_i915_gem_object *obj,
int align)
@@ -340,7 +326,11 @@ i915_gem_object_attach_phys(struct drm_i915_gem_object *obj,
if (obj->base.filp == NULL)
return -EINVAL;

- ret = drop_pages(obj);
+ ret = i915_gem_object_unbind(obj);
+ if (ret)
+ return ret;
+
+ ret = i915_gem_object_put_pages(obj);
if (ret)
return ret;

--
2.8.1