linux-kernel - Re: Kernel Oops: btusb: 4.2rc1 System lockup with BT dongle insert

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Message-ID: <d51df2e1e321efc18d74f3cc33bd4106.squirrel@mungewell.org>
Date:	Fri, 17 Jul 2015 11:14:37 -0400
From:	simon@...gewell.org
To:	"Kim, Milo" <milo.kim@...com>
Cc:	linux-bluetooth@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: Kernel Oops: btusb: 4.2rc1 System lockup with BT dongle insert -
 log attached


>> So in summary this problem is showing up now as the 'User Helper
>> Fallback'
>> is now forced on, obviously the underlying problem needs to be fixed -
>> but
>> I don't know when it crept in.
>>
>
> The 'CONFIG_FW_LOADER_USER_HELPER_FALLBACK' enables to load firmware
> data manually by accessing /sys/class/firmware/<name>/data. It runs in
> case the firmware file is missing.
> This user helper fallback will be enabled if one of LP55xx driver is
> included in your dot config. Please see my patch below.
>
> https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/drivers/leds?id=b67893206fc0a0e8af87130e67f3d8ae553fc87c
>
> However, I'm not sure why this affects your system lockup. Can I have
> more details?

Hi Milo,
I'm not suggesting that your patch is the cause, just that it is an
'enabler' and and explains why the problem (system lockup when I plug USB
Bluetooth dongle in) appears now.

A full Oops log is further back in this thread:
http://www.spinics.net/lists/linux-bluetooth/msg63090.html


>> Will try building 4.1 with this option to see if it fails.

A very quick test as I was leaving the house this morning shows that 4.1
with 'CONFIG_FW_LOADER_USER_HELPER_FALLBACK' does not show the problem.

So at least we know the 'real' problem is a recent change to the code.
Simon

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