drm/i915: Fix type mismatch and accounting in i915_gem_shrink

The interface uses an unsigned long, and we can use the unsigned counter
throughout our code, so do so. In the process, we notice one instance
where the shrink count is based on a heuristic rather than the result,
and another where we ask for too many pages to be purged.

v2: nr_to_scan needs to be promoted to a long as well, so just use
    sc->nr_to_scan directly.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/i915/i915_gem.c

@@ -64,8 +64,8 @@ static unsigned long i915_gem_inactive_count(struct shrinker *shrinker,
 					     struct shrink_control *sc);
 static unsigned long i915_gem_inactive_scan(struct shrinker *shrinker,
 					    struct shrink_control *sc);
-static long i915_gem_purge(struct drm_i915_private *dev_priv, long target);
-static long i915_gem_shrink_all(struct drm_i915_private *dev_priv);
+static unsigned long i915_gem_purge(struct drm_i915_private *dev_priv, long target);
+static unsigned long i915_gem_shrink_all(struct drm_i915_private *dev_priv);
 static void i915_gem_object_truncate(struct drm_i915_gem_object *obj);
 
 static bool cpu_cache_is_coherent(struct drm_device *dev,
@@ -1728,13 +1728,13 @@ i915_gem_object_put_pages(struct drm_i915_gem_object *obj)
 	return 0;
 }
 
-static long
+static unsigned long
 __i915_gem_shrink(struct drm_i915_private *dev_priv, long target,
 		  bool purgeable_only)
 {
 	struct list_head still_bound_list;
 	struct drm_i915_gem_object *obj, *next;
-	long count = 0;
+	unsigned long count = 0;
 
 	list_for_each_entry_safe(obj, next,
 				 &dev_priv->mm.unbound_list,
@@ -1800,13 +1800,13 @@ __i915_gem_shrink(struct drm_i915_private *dev_priv, long target,
 	return count;
 }
 
-static long
+static unsigned long
 i915_gem_purge(struct drm_i915_private *dev_priv, long target)
 {
 	return __i915_gem_shrink(dev_priv, target, true);
 }
 
-static long
+static unsigned long
 i915_gem_shrink_all(struct drm_i915_private *dev_priv)
 {
 	struct drm_i915_gem_object *obj, *next;
@@ -1816,9 +1816,8 @@ i915_gem_shrink_all(struct drm_i915_private *dev_priv)
 
 	list_for_each_entry_safe(obj, next, &dev_priv->mm.unbound_list,
 				 global_list) {
-		if (obj->pages_pin_count == 0)
+		if (i915_gem_object_put_pages(obj) == 0)
 			freed += obj->base.size >> PAGE_SHIFT;
-		i915_gem_object_put_pages(obj);
 	}
 	return freed;
 }
@@ -4947,6 +4946,7 @@ i915_gem_inactive_count(struct shrinker *shrinker, struct shrink_control *sc)
 
 	if (unlock)
 		mutex_unlock(&dev->struct_mutex);
+
 	return count;
 }
 
@@ -5018,7 +5018,6 @@ i915_gem_inactive_scan(struct shrinker *shrinker, struct shrink_control *sc)
 			     struct drm_i915_private,
 			     mm.inactive_shrinker);
 	struct drm_device *dev = dev_priv->dev;
-	int nr_to_scan = sc->nr_to_scan;
 	unsigned long freed;
 	bool unlock = true;
 
@@ -5032,15 +5031,17 @@ i915_gem_inactive_scan(struct shrinker *shrinker, struct shrink_control *sc)
 		unlock = false;
 	}
 
-	freed = i915_gem_purge(dev_priv, nr_to_scan);
-	if (freed < nr_to_scan)
-		freed += __i915_gem_shrink(dev_priv, nr_to_scan,
-							false);
-	if (freed < nr_to_scan)
+	freed = i915_gem_purge(dev_priv, sc->nr_to_scan);
+	if (freed < sc->nr_to_scan)
+		freed += __i915_gem_shrink(dev_priv,
+					   sc->nr_to_scan - freed,
+					   false);
+	if (freed < sc->nr_to_scan)
 		freed += i915_gem_shrink_all(dev_priv);
 
 	if (unlock)
 		mutex_unlock(&dev->struct_mutex);
+
 	return freed;
 }