Re: [PATCH 07/13] drm/i915: Introduce dedicated object VMA iterator

Chris Wilson
2016-01-08T11:44:08Z

On Fri, Jan 08, 2016 at 11:29:46AM +0000, Tvrtko Ursulin wrote:
> From: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
>
> Purpose is to catch places which iterate the object VMA list
> without holding the big lock.
>
> Implemented by open coding list_for_each_entry to make the
> macro compatible with existing call sites.
>
> Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
> Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
> +#define i915_gem_obj_for_each_vma(vma, obj) \
> + for (WARN_ON_ONCE(!mutex_is_locked(&(obj)->base.dev->struct_mutex)), \

Let's not go around adding WARN(!mutex_locked) to GEM code when
lockdep_assert_held doesn't add overhead outside of testing.
-Chris

--
Chris Wilson, Intel Open Source Technology Centre