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

drivers/gpu/drm/i915/i915_debugfs.c

@@ -174,6 +174,9 @@ describe_obj(struct seq_file *m, struct drm_i915_gem_object *obj)
 	if (obj->fence_reg != I915_FENCE_REG_NONE)
 		seq_printf(m, " (fence: %d)", obj->fence_reg);
 	list_for_each_entry(vma, &obj->vma_list, obj_link) {
+		if (!drm_mm_node_allocated(&vma->node))
+			continue;
+
 		seq_printf(m, " (%sgtt offset: %08llx, size: %08llx",
 			   vma->is_ggtt ? "g" : "pp",
 			   vma->node.start, vma->node.size);
@@ -335,20 +338,18 @@ static int per_file_stats(int id, void *ptr, void *data)
 	struct drm_i915_gem_object *obj = ptr;
 	struct file_stats *stats = data;
 	struct i915_vma *vma;
-	int bound = 0;
 
 	stats->count++;
 	stats->total += obj->base.size;
-
+	if (!obj->bind_count)
+		stats->unbound += obj->base.size;
 	if (obj->base.name || obj->base.dma_buf)
 		stats->shared += obj->base.size;
 
 	list_for_each_entry(vma, &obj->vma_list, obj_link) {
 		if (!drm_mm_node_allocated(&vma->node))
 			continue;
 
-		bound++;
-
 		if (vma->is_ggtt) {
 			stats->global += vma->node.size;
 		} else {
@@ -364,9 +365,6 @@ static int per_file_stats(int id, void *ptr, void *data)
 			stats->inactive += vma->node.size;
 	}
 
-	if (!bound)
-		stats->unbound += obj->base.size;
-
 	return 0;
 }
 

drivers/gpu/drm/i915/i915_drv.h

@@ -2221,6 +2221,8 @@ struct drm_i915_gem_object {
 	unsigned int frontbuffer_bits:INTEL_FRONTBUFFER_BITS;
 
 	unsigned int has_wc_mmap;
+	/** Count of VMA actually bound by this object */
+	unsigned int bind_count;
 	unsigned int pin_display;
 
 	struct sg_table *pages;
@@ -3266,7 +3268,6 @@ i915_gem_obj_ggtt_offset(struct drm_i915_gem_object *o)
 	return i915_gem_obj_ggtt_offset_view(o, &i915_ggtt_view_normal);
 }
 
-bool i915_gem_obj_bound_any(struct drm_i915_gem_object *o);
 bool i915_gem_obj_ggtt_bound_view(struct drm_i915_gem_object *o,
 				  const struct i915_ggtt_view *view);
 bool i915_gem_obj_bound(struct drm_i915_gem_object *o,

drivers/gpu/drm/i915/i915_gem.c

@@ -2107,7 +2107,7 @@ i915_gem_object_put_pages(struct drm_i915_gem_object *obj)
 	if (obj->pages_pin_count)
 		return -EBUSY;
 
-	BUG_ON(i915_gem_obj_bound_any(obj));
+	GEM_BUG_ON(obj->bind_count);
 
 	/* ->put_pages might need to allocate memory for the bit17 swizzle
 	 * array, hence protect them from being reaped by removing them from gtt
@@ -2965,7 +2965,6 @@ static void __i915_vma_iounmap(struct i915_vma *vma)
 static int __i915_vma_unbind(struct i915_vma *vma, bool wait)
 {
 	struct drm_i915_gem_object *obj = vma->obj;
-	struct drm_i915_private *dev_priv = to_i915(obj->base.dev);
 	int ret;
 
 	if (list_empty(&vma->obj_link))
@@ -2979,7 +2978,8 @@ static int __i915_vma_unbind(struct i915_vma *vma, bool wait)
 	if (vma->pin_count)
 		return -EBUSY;
 
-	BUG_ON(obj->pages == NULL);
+	GEM_BUG_ON(obj->bind_count == 0);
+	GEM_BUG_ON(!obj->pages);
 
 	if (wait) {
 		ret = i915_gem_object_wait_rendering(obj, false);
@@ -3019,8 +3019,9 @@ static int __i915_vma_unbind(struct i915_vma *vma, bool wait)
 
 	/* Since the unbound list is global, only move to that list if
 	 * no more VMAs exist. */
-	if (list_empty(&obj->vma_list))
-		list_move_tail(&obj->global_list, &dev_priv->mm.unbound_list);
+	if (--obj->bind_count == 0)
+		list_move_tail(&obj->global_list,
+			       &to_i915(obj->base.dev)->mm.unbound_list);
 
 	/* And finally now the object is completely decoupled from this vma,
 	 * we can drop its hold on the backing storage and allow it to be
@@ -3255,6 +3256,7 @@ i915_gem_object_bind_to_vm(struct drm_i915_gem_object *obj,
 
 	list_move_tail(&obj->global_list, &dev_priv->mm.bound_list);
 	list_add_tail(&vma->vm_link, &vm->inactive_list);
+	obj->bind_count++;
 
 	return vma;
 
@@ -3450,7 +3452,6 @@ int i915_gem_object_set_cache_level(struct drm_i915_gem_object *obj,
 {
 	struct drm_device *dev = obj->base.dev;
 	struct i915_vma *vma, *next;
-	bool bound = false;
 	int ret = 0;
 
 	if (obj->cache_level == cache_level)
@@ -3474,8 +3475,7 @@ int i915_gem_object_set_cache_level(struct drm_i915_gem_object *obj,
 			ret = i915_vma_unbind(vma);
 			if (ret)
 				return ret;
-		} else
-			bound = true;
+		}
 	}
 
 	/* We can reuse the existing drm_mm nodes but need to change the
@@ -3485,7 +3485,7 @@ int i915_gem_object_set_cache_level(struct drm_i915_gem_object *obj,
 	 * rewrite the PTE in the belief that doing so tramples upon less
 	 * state and so involves less work.
 	 */
-	if (bound) {
+	if (obj->bind_count) {
 		/* Before we change the PTE, the GPU must not be accessing it.
 		 * If we wait upon the object, we know that all the bound
 		 * VMA are no longer active.
@@ -4223,6 +4223,7 @@ void i915_gem_free_object(struct drm_gem_object *gem_obj)
 			dev_priv->mm.interruptible = was_interruptible;
 		}
 	}
+	GEM_BUG_ON(obj->bind_count);
 
 	/* Stolen objects don't hold a ref, but do hold pin count. Fix that up
 	 * before progressing. */
@@ -4840,17 +4841,6 @@ bool i915_gem_obj_ggtt_bound_view(struct drm_i915_gem_object *o,
 	return false;
 }
 
-bool i915_gem_obj_bound_any(struct drm_i915_gem_object *o)
-{
-	struct i915_vma *vma;
-
-	list_for_each_entry(vma, &o->vma_list, obj_link)
-		if (drm_mm_node_allocated(&vma->node))
-			return true;
-
-	return false;
-}
-
 unsigned long i915_gem_obj_ggtt_size(struct drm_i915_gem_object *o)
 {
 	struct i915_vma *vma;

drivers/gpu/drm/i915/i915_gem_shrinker.c

@@ -48,19 +48,15 @@ static bool mutex_is_locked_by(struct mutex *mutex, struct task_struct *task)
 #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 @@ static bool can_release_pages(struct drm_i915_gem_object *obj)
 	 * 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

drivers/gpu/drm/i915/i915_gem_stolen.c

@@ -708,6 +708,7 @@ i915_gem_object_create_stolen_for_preallocated(struct drm_device *dev,
 	vma->bound |= GLOBAL_BIND;
 	__i915_vma_set_map_and_fenceable(vma);
 	list_add_tail(&vma->vm_link, &ggtt->base.inactive_list);
+	obj->bind_count++;
 
 	list_add_tail(&obj->global_list, &dev_priv->mm.bound_list);
 	i915_gem_object_pin_pages(obj);