If we bail out of the submit before actually adding the cmdstream
to the kernel ring there is no valid fence to put. Make sure to skip
the fence_put in that case.
Signed-off-by: Lucas Stach <l.stach@pengutronix.de>
 
                /* initially, until copy_from_user() and bo lookup succeeds: */
                submit->nr_bos = 0;
+               submit->fence = NULL;
 
                ww_acquire_init(&submit->ticket, &reservation_ww_class);
        }
        }
 
        ww_acquire_fini(&submit->ticket);
-       dma_fence_put(submit->fence);
+       if (submit->fence)
+               dma_fence_put(submit->fence);
        kfree(submit);
 }