drm: extract legacy ctxbitmap flushing

The ctxbitmap code is only used by legacy drivers so lets try to keep it
as separated as possible. Furthermore, the locking is non-obvious and
kinda weird with ctxlist_mutex *and* struct_mutex. Keeping all ctxbitmap
access in one file is much easier to review and makes drm_release() more
readable.

Reviewed-by: Alex Deucher <alexander.deucher@amd.com>
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: David Herrmann <dh.herrmann@gmail.com>
diff --git a/drivers/gpu/drm/drm_fops.c b/drivers/gpu/drm/drm_fops.c
index bc583fe..55143f7 100644
--- a/drivers/gpu/drm/drm_fops.c
+++ b/drivers/gpu/drm/drm_fops.c
@@ -457,25 +457,7 @@
 	if (dev->driver->driver_features & DRIVER_GEM)
 		drm_gem_release(dev, file_priv);
 
-	mutex_lock(&dev->ctxlist_mutex);
-	if (!list_empty(&dev->ctxlist)) {
-		struct drm_ctx_list *pos, *n;
-
-		list_for_each_entry_safe(pos, n, &dev->ctxlist, head) {
-			if (pos->tag == file_priv &&
-			    pos->handle != DRM_KERNEL_CONTEXT) {
-				if (dev->driver->context_dtor)
-					dev->driver->context_dtor(dev,
-								  pos->handle);
-
-				drm_ctxbitmap_free(dev, pos->handle);
-
-				list_del(&pos->head);
-				kfree(pos);
-			}
-		}
-	}
-	mutex_unlock(&dev->ctxlist_mutex);
+	drm_ctxbitmap_flush(dev, file_priv);
 
 	mutex_lock(&dev->master_mutex);