Re: w1: 3.14-rc7 - possible recursive locking detected

[Dr. H. Nikolaus Schaller]

Hi,

Am 23.03.2014 um 22:50 schrieb David Fries:

> On Mon, Mar 17, 2014 at 10:38:13PM +0100, Belisko Marek wrote:
>> Hi,
>> 
>> booting latest 3.14-rc7 on gta04 board gives following warning:
>> 
>> [    3.101409] Driver for 1-wire Dallas network protocol.
>> [    3.109649] omap_hdq omap_hdq: OMAP HDQ Hardware Rev 0.5. Driver in
>> [    3.400146]        CPU0
>> [    3.402709]        ----
>> [    3.405273]   lock(&(&priv->bus_notifier)->rwsem);
>> [    3.410308]   lock(&(&priv->bus_notifier)->rwsem);
>> [    3.415374]
>> [    3.415374]  *** DEADLOCK ***
>> 
>> AFAIK we didn't see that on (at least 3/14-rc2).
> 
> The last drivers/w1 change went in before v3.14-rc1, so if it is
> something in the w1 code, it has either been there or something else
> in the rest of the kernel changed to expose it.  I'm using the ds2490
> USB w1 dongle, I didn't see that problem when enabling lock debugging
> on 3.14.0-rc5+ which includes some changes I'm working on.
> 
> https://github.com/dfries/linux.git w1_rework

Further analysis shows that It only occurs when using the device tree.

So it may have to do something with nested driver probing/locking running
differently between DT and board file.

BR,
Nikolaus

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