drm/i915: Context objects can never be active when freed

Due to how we only release the pining on the context state on
retirement and never track activity on the context vma itself, the
object can never be active at the point of release. Replace the
conditional transfer of ownership onto an active-reference with an
assert that the object is idle.
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20180625100604.22598-2-chris@chris-wilson.co.uk

drivers/gpu/drm/i915/intel_lrc.c

@@ -1344,7 +1344,9 @@ static void execlists_context_destroy(struct intel_context *ce)
 		return;
 
 	intel_ring_free(ce->ring);
-	__i915_gem_object_release_unless_active(ce->state->obj);
+
+	GEM_BUG_ON(i915_gem_object_is_active(ce->state->obj));
+	i915_gem_object_put(ce->state->obj);
 }
 
 static void execlists_context_unpin(struct intel_context *ce)

drivers/gpu/drm/i915/intel_ringbuffer.c

@@ -1167,8 +1167,11 @@ static void intel_ring_context_destroy(struct intel_context *ce)
 {
 	GEM_BUG_ON(ce->pin_count);
 
-	if (ce->state)
-		__i915_gem_object_release_unless_active(ce->state->obj);
+	if (!ce->state)
+		return;
+
+	GEM_BUG_ON(i915_gem_object_is_active(ce->state->obj));
+	i915_gem_object_put(ce->state->obj);
 }
 
 static int __context_pin_ppgtt(struct i915_gem_context *ctx)