drm/i915: Convert BUG_ON(pin_count) from an impossible condition

Also spotted by Dan Carpenter.

obj->pin_count is unsigned so the BUG_ON(obj->pin_count<0) will never
trigger.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>

1 files changed, 3 insertions, 13 deletions

diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
index 7569b77fb403..08f57aedaf51 100644
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -4128,12 +4128,7 @@ i915_gem_object_pin(struct drm_gem_object *obj, uint32_t alignment,
                         return ret;
         }
 
-        obj_priv->pin_count++;
-
-        /* If the object is not active and not pending a flush,
-         * remove it from the inactive list
-         */
-        if (obj_priv->pin_count == 1) {
+        if (obj_priv->pin_count++ == 0) {
                 i915_gem_info_add_pin(dev_priv, obj, mappable);
                 if (!obj_priv->active)
                         list_move_tail(&obj_priv->mm_list,
@@ -4153,15 +4148,10 @@ i915_gem_object_unpin(struct drm_gem_object *obj)
         struct drm_i915_gem_object *obj_priv = to_intel_bo(obj);
 
         WARN_ON(i915_verify_lists(dev));
-        obj_priv->pin_count--;
-        BUG_ON(obj_priv->pin_count < 0);
+        BUG_ON(obj_priv->pin_count == 0);
         BUG_ON(obj_priv->gtt_space == NULL);
 
-        /* If the object is no longer pinned, and is
-         * neither active nor being flushed, then stick it on
-         * the inactive list
-         */
-        if (obj_priv->pin_count == 0) {
+        if (--obj_priv->pin_count == 0) {
                 if (!obj_priv->active)
                         list_move_tail(&obj_priv->mm_list,
                                        &dev_priv->mm.inactive_list);