From 1d425aa6a14b7d877d6a52eb681d6dfe9e31c610 Mon Sep 17 00:00:00 2001
From: Jiri Slaby <jslaby@suse.cz>
Date: Sun, 1 Apr 2018 12:53:52 +0200
Subject: [PATCH] DRM fix

Signed-off-by: Jiri Slaby <jslaby@suse.cz>
---
 drivers/gpu/drm/drm_dp_mst_topology.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/drm_dp_mst_topology.c b/drivers/gpu/drm/drm_dp_mst_topology.c
index 70dcfa58d3c2..f07bfb5f4073 100644
--- a/drivers/gpu/drm/drm_dp_mst_topology.c
+++ b/drivers/gpu/drm/drm_dp_mst_topology.c
@@ -1288,7 +1288,10 @@ static struct drm_dp_mst_branch *drm_dp_get_mst_branch_device(struct drm_dp_mst_
 			}
 		}
 	}
-	kref_get(&mstb->kref);
+	if (WARN_ON_ONCE(!mstb))
+		;
+	else
+		kref_get(&mstb->kref);
 out:
 	mutex_unlock(&mgr->lock);
 	return mstb;
-- 
2.16.3