Re: [PATCH] Bluetooth: hci_serdev: Init hci_uart proto_lock to avoid oops

From: Lukas Wunner
Date: Thu Nov 16 2017 - 19:00:06 EST

On Fri, Nov 17, 2017 at 12:54:53AM +0100, Lukas Wunner wrote:
> John Stultz reports a boot time crash with the HiKey board (which uses
> hci_serdev) occurring in hci_uart_tx_wakeup(). That function is
> contained in hci_ldisc.c, but also called from the newer hci_serdev.c.
> It acquires the proto_lock in struct hci_uart and it turns out that we
> forgot to init the lock in the serdev code path, thus causing the crash.
> John bisected the crash to commit 67d2f8781b9f ("Bluetooth: hci_ldisc:
> Allow sleeping while proto locks are held"), but the issue was present
> before and the commit merely exposed it. (Perhaps by luck, the crash
> did not occur with rwlocks.)
> Init the proto_lock in the serdev code path to avoid the oops.

Apologies, I botched Gustavo Padovan's and Johan Hedberg's e-mail
address in the To: header, please fix up when replying.