INFO: trying to register non-static key.
the code is fine but needs lockdep annotation.
turning off the locking correctness validator.
CPU: 1 PID: 1285 Comm: kworker/u5:0 Not tainted 5.1.0-rc5-next-20190417 #27
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Workqueue: hci1 hci_cmd_work
Call Trace:
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack+0x172/0x1f0 lib/dump_stack.c:113
 assign_lock_key kernel/locking/lockdep.c:775 [inline]
 register_lock_class+0x167e/0x1860 kernel/locking/lockdep.c:1084
 __lock_acquire+0xf9/0x3fb0 kernel/locking/lockdep.c:3571
 lock_acquire+0x16f/0x3f0 kernel/locking/lockdep.c:4200
 percpu_down_read include/linux/percpu-rwsem.h:36 [inline]
 hci_uart_send_frame+0x85/0x470 drivers/bluetooth/hci_ldisc.c:287
 hci_send_frame+0x1b8/0x2d0 net/bluetooth/hci_core.c:3584
 hci_cmd_work+0x137/0x270 net/bluetooth/hci_core.c:4497
 process_one_work+0x98e/0x1790 kernel/workqueue.c:2268
 worker_thread+0x98/0xe40 kernel/workqueue.c:2414
 kthread+0x357/0x430 kernel/kthread.c:254
 ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:352