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>

drivers/gpu/drm/drm_stub.c

@@ -109,7 +109,6 @@ EXPORT_SYMBOL(drm_ut_debug_printk);
 
 static int drm_minor_get_id(struct drm_device *dev, int type)
 {
-	int new_id;
 	int ret;
 	int base = 0, limit = 63;
 
@@ -121,25 +120,11 @@ static int drm_minor_get_id(struct drm_device *dev, int type)
                 limit = base + 255;
         }
 
-again:
-	if (idr_pre_get(&drm_minors_idr, GFP_KERNEL) == 0) {
-		DRM_ERROR("Out of memory expanding drawable idr\n");
-		return -ENOMEM;
-	}
 	mutex_lock(&dev->struct_mutex);
-	ret = idr_get_new_above(&drm_minors_idr, NULL,
-				base, &new_id);
+	ret = idr_alloc(&drm_minors_idr, NULL, base, limit, GFP_KERNEL);
 	mutex_unlock(&dev->struct_mutex);
-	if (ret == -EAGAIN)
-		goto again;
-	else if (ret)
-		return ret;
 
-	if (new_id >= limit) {
-		idr_remove(&drm_minors_idr, new_id);
-		return -EINVAL;
-	}
-	return new_id;
+	return ret == -ENOSPC ? -EINVAL : ret;
 }
 
 struct drm_master *drm_master_create(struct drm_minor *minor)