[RFC PATCH 072/162] drm/i915: Avoid some false positives in assert_object_held()

[Matthew Auld]

From: Thomas Hellström <thomas.hellstrom at intel.com>

In a ww transaction where we've already locked a reservation
object, assert_object_held() might not throw a splat even if
the object is unlocked. Improve on that situation by asserting
that the reservation object's ww mutex is indeed locked.

Signed-off-by: Thomas Hellström <thomas.hellstrom at intel.com>
Cc: Matthew Auld <matthew.auld at intel.com>
---
 drivers/gpu/drm/i915/gem/i915_gem_object.h | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/i915/gem/i915_gem_object.h b/drivers/gpu/drm/i915/gem/i915_gem_object.h
index d0cc62d1c65e..d56643b3b518 100644
--- a/drivers/gpu/drm/i915/gem/i915_gem_object.h
+++ b/drivers/gpu/drm/i915/gem/i915_gem_object.h
@@ -117,7 +117,14 @@ i915_gem_object_put(struct drm_i915_gem_object *obj)
 	__drm_gem_object_put(&obj->base);
 }
 
-#define assert_object_held(obj) dma_resv_assert_held((obj)->base.resv)
+#ifdef CONFIG_LOCKDEP
+#define assert_object_held(obj) do {					\
+		dma_resv_assert_held((obj)->base.resv);			\
+		WARN_ON(!ww_mutex_is_locked(&(obj)->base.resv->lock)); \
+	} while (0)
+#else
+#define assert_object_held(obj) do { } while (0)
+#endif
 
 #define object_is_isolated(obj)					\
 	(!IS_ENABLED(CONFIG_LOCKDEP) ||				\
-- 
2.26.2