drm/i915: Count how many VMA are bound for an object

Since we may have VMA allocated for an object, but we interrupted their
binding, there is a disparity between have elements on the obj->vma_list
and being bound. i915_gem_obj_bound_any() does this check, but this is
not rigorously observed - add an explicit count to make it easier.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Reviewed-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1470293567-10811-7-git-send-email-chris@chris-wilson.co.uk
diff --git a/drivers/gpu/drm/i915/i915_gem_shrinker.c b/drivers/gpu/drm/i915/i915_gem_shrinker.c
index 5d4772c..b95cd9f 100644
--- a/drivers/gpu/drm/i915/i915_gem_shrinker.c
+++ b/drivers/gpu/drm/i915/i915_gem_shrinker.c
@@ -48,19 +48,15 @@
 #endif
 }
 
-static int num_vma_bound(struct drm_i915_gem_object *obj)
+static bool any_vma_pinned(struct drm_i915_gem_object *obj)
 {
 	struct i915_vma *vma;
-	int count = 0;
 
-	list_for_each_entry(vma, &obj->vma_list, obj_link) {
-		if (drm_mm_node_allocated(&vma->node))
-			count++;
+	list_for_each_entry(vma, &obj->vma_list, obj_link)
 		if (vma->pin_count)
-			count++;
-	}
+			return true;
 
-	return count;
+	return false;
 }
 
 static bool swap_available(void)
@@ -82,7 +78,10 @@
 	 * to the GPU, simply unbinding from the GPU is not going to succeed
 	 * in releasing our pin count on the pages themselves.
 	 */
-	if (obj->pages_pin_count != num_vma_bound(obj))
+	if (obj->pages_pin_count > obj->bind_count)
+		return false;
+
+	if (any_vma_pinned(obj))
 		return false;
 
 	/* We can only return physical pages to the system if we can either