linux-kernel - Re: [PATCH] Bluetooth: hci_serdev: Init hci_uart proto

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Message-ID: <20171116235955.GA27601@wunner.de>
Date:   Fri, 17 Nov 2017 00:59:55 +0100
From:   Lukas Wunner <lukas@...ner.de>
To:     Marcel Holtmann <marcel@...tmann.org>,
        Gustavo Padovan <gustavo@...ovan.org>,
        Johan Hedberg <johan.hedberg@...il.com>,
        Rob Herring <rob.herring@...aro.org>,
        Johan Hovold <johan@...nel.org>
Cc:     Ronald Tschalaer <ronald@...ovation.ch>,
        Sumit Semwal <sumit.semwal@...aro.org>,
        linux-bluetooth@...r.kernel.org, linux-kernel@...r.kernel.org,
        John Stultz <john.stultz@...aro.org>
Subject: Re: [PATCH] Bluetooth: hci_serdev: Init hci_uart proto_lock to avoid
 oops

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.

Lukas