drm/i915: add i915_address_space_fini

We already have an i915_address_space_init, so for symmetry we should
also have a _fini, plus we already open code it twice. This then also
fixes a bug where we leak the timeline for the ggtt vm.

v2: don't forget about the struct_mutex for the ggtt path.

Fixes: 80b204bc ("drm/i915: Enable multiple timelines")
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Matthew Auld <matthew.auld@intel.com>
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Link: http://patchwork.freedesktop.org/patch/msgid/20161117210411.14044-1-chris@chris-wilson.co.uk

drivers/gpu/drm/i915/i915_gem_gtt.c

@@ -2196,6 +2196,13 @@ static void i915_address_space_init(struct i915_address_space *vm,
 	list_add_tail(&vm->global_link, &dev_priv->vm_list);
 }
 
+static void i915_address_space_fini(struct i915_address_space *vm)
+{
+	i915_gem_timeline_fini(&vm->timeline);
+	drm_mm_takedown(&vm->mm);
+	list_del(&vm->global_link);
+}
+
 static void gtt_write_workarounds(struct drm_i915_private *dev_priv)
 {
 	/* This function is for gtt related workarounds. This function is
@@ -2290,9 +2297,7 @@ void  i915_ppgtt_release(struct kref *kref)
 	WARN_ON(!list_empty(&ppgtt->base.inactive_list));
 	WARN_ON(!list_empty(&ppgtt->base.unbound_list));
 
-	i915_gem_timeline_fini(&ppgtt->base.timeline);
-	list_del(&ppgtt->base.global_link);
-	drm_mm_takedown(&ppgtt->base.mm);
+	i915_address_space_fini(&ppgtt->base);
 
 	ppgtt->base.cleanup(&ppgtt->base);
 	kfree(ppgtt);
@@ -2833,8 +2838,9 @@ void i915_ggtt_cleanup_hw(struct drm_i915_private *dev_priv)
 	if (drm_mm_initialized(&ggtt->base.mm)) {
 		intel_vgt_deballoon(dev_priv);
 
-		drm_mm_takedown(&ggtt->base.mm);
-		list_del(&ggtt->base.global_link);
+		mutex_lock(&dev_priv->drm.struct_mutex);
+		i915_address_space_fini(&ggtt->base);
+		mutex_unlock(&dev_priv->drm.struct_mutex);
 	}
 
 	ggtt->base.cleanup(&ggtt->base);