drm: convert to idr_alloc()

Convert to the much saner new idr interface.

* drm_ctxbitmap_next() error handling in drm_addctx() seems broken.
  drm_ctxbitmap_next() return -errno on failure not -1.

[artem.savkov@gmail.com: missing idr_preload_end in drm_gem_flink_ioctl]
[jslaby@suse.cz: fix drm_gem_flink_ioctl() return value]
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: David Airlie <airlied@linux.ie>
Signed-off-by: Artem Savkov <artem.savkov@gmail.com>
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/drivers/gpu/drm/drm_crtc.c b/drivers/gpu/drm/drm_crtc.c
index 99928b9..792c3e3 100644
--- a/drivers/gpu/drm/drm_crtc.c
+++ b/drivers/gpu/drm/drm_crtc.c
@@ -266,32 +266,21 @@
 static int drm_mode_object_get(struct drm_device *dev,
 			       struct drm_mode_object *obj, uint32_t obj_type)
 {
-	int new_id = 0;
 	int ret;
 
-again:
-	if (idr_pre_get(&dev->mode_config.crtc_idr, GFP_KERNEL) == 0) {
-		DRM_ERROR("Ran out memory getting a mode number\n");
-		return -ENOMEM;
-	}
-
 	mutex_lock(&dev->mode_config.idr_mutex);
-	ret = idr_get_new_above(&dev->mode_config.crtc_idr, obj, 1, &new_id);
-
-	if (!ret) {
+	ret = idr_alloc(&dev->mode_config.crtc_idr, obj, 1, 0, GFP_KERNEL);
+	if (ret >= 0) {
 		/*
 		 * Set up the object linking under the protection of the idr
 		 * lock so that other users can't see inconsistent state.
 		 */
-		obj->id = new_id;
+		obj->id = ret;
 		obj->type = obj_type;
 	}
 	mutex_unlock(&dev->mode_config.idr_mutex);
 
-	if (ret == -EAGAIN)
-		goto again;
-
-	return ret;
+	return ret < 0 ? ret : 0;
 }
 
 /**