From: Ben Skeggs <bskeggs@redhat.com>
Date: Fri, 15 Jun 2018 07:59:28 +1000
Subject: drm/nouveau/core: ERR_PTR vs NULL bug in nvkm_engine_info()
Git-commit: f7fbbf2ccaa0f557c4615a5cf3e1e5704585628a
Patch-mainline: v4.19-rc1
References: FATE#326289 FATE#326079 FATE#326049 FATE#322398 FATE#326166

Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Ben Skeggs <bskeggs@redhat.com>
Acked-by: Petr Tesarik <ptesarik@suse.com>
---
 drivers/gpu/drm/nouveau/nvkm/core/engine.c |    3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

--- a/drivers/gpu/drm/nouveau/nvkm/core/engine.c
+++ b/drivers/gpu/drm/nouveau/nvkm/core/engine.c
@@ -87,11 +87,12 @@ nvkm_engine_info(struct nvkm_subdev *sub
 {
 	struct nvkm_engine *engine = nvkm_engine(subdev);
 	if (engine->func->info) {
-		if ((engine = nvkm_engine_ref(engine))) {
+		if (!IS_ERR((engine = nvkm_engine_ref(engine)))) {
 			int ret = engine->func->info(engine, mthd, data);
 			nvkm_engine_unref(&engine);
 			return ret;
 		}
+		return PTR_ERR(engine);
 	}
 	return -ENOSYS;
 }