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Subject: Re: [PATCH] Bluetooth: hci_serdev: Init hci_uart proto_lock to avoid
 oops
From: Marcel Holtmann <marcel@holtmann.org>
In-Reply-To: <CALAqxLWbh=pmbZEfa03LvOTxBD7bnPVNdHs-os5xZjvhkSWT2Q@mail.gmail.com>
Date: Tue, 2 Jan 2018 21:45:44 +0100
Cc: Lukas Wunner <lukas@wunner.de>,
        Rob Herring <rob.herring@linaro.org>,
        Johan Hovold <johan@kernel.org>,
        Ronald Tschalaer <ronald@innovation.ch>,
        Sumit Semwal <sumit.semwal@linaro.org>,
        "open list:BLUETOOTH DRIVERS" <linux-bluetooth@vger.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Message-Id: <D250C682-CAD9-48FD-9B82-25E6934AAC0D@holtmann.org>
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 <20171116213045.GA17506@wunner.de> <20171116214504.GB17506@wunner.de>
 <CALAqxLX-qp=rc8P7ynGrUwWHgP2EBAwoEES-aOOuehtnJSDR+A@mail.gmail.com>
 <f181189de5fd4c75da4708425df99e70abc6a127.1510875912.git.lukas@wunner.de>
 <25BE9D66-9609-42D0-8A83-E15758FA3A1B@holtmann.org>
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To: John Stultz <john.stultz@linaro.org>
Sender: linux-kernel-owner@vger.kernel.org
List-ID: <linux-bluetooth.vger.kernel.org>

Hi John,

>>>> 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.
>>>> 
>> [snip]
>>> patch has been applied to bluetooth-next tree.
>> 
>> Sorry to be a nuisance if its just a timing thing, but I wanted to
>> follow up on this just to make sure it didn't fall through the cracks,
>> as I noticed w/ -rc3 it hasn't landed yet.
> 
> Happy new year all,
>  Just wanted to send another ping on this as it seems it hasn't made
> it into -rc6. Did this get missed as being tagged as a (at least
> functional) regression fix?

since it wasn’t marked as urgent fix, it never went on the path to -rc. It is on the path for the next release. And then can be included in -stable if needed.

Regards

Marcel