Re: [PATCH 1/5] input: twl6040-vibra: fix DT node memory management
From: H. Nikolaus Schaller
Date: Wed Apr 20 2016 - 05:03:22 EST
> Am 19.04.2016 um 19:06 schrieb Dmitry Torokhov <dmitry.torokhov@xxxxxxxxx>:
>
> On Tue, Apr 19, 2016 at 09:43:08AM +0200, H. Nikolaus Schaller wrote:
>>
>>> Am 18.04.2016 um 23:22 schrieb Dmitry Torokhov <dmitry.torokhov@xxxxxxxxx>:
>>>
>>> On Mon, Apr 18, 2016 at 09:55:37PM +0200, H. Nikolaus Schaller wrote:
>>>> commit e7ec014a47e4 ("Input: twl6040-vibra - update for device tree support")
>>>>
>>>> made the separate vibra DT node to a subnode of the twl6040.
>>>>
>>>> It now calls of_find_node_by_name() to locate the "vibra" subnode.
>>>> This function has a side effect to call of_node_put on() for the twl6040
>>>> parent node passed in as a parameter. This causes trouble later on.
>>>>
>>>> Solution: we must call of_node_get() before of_find_node_by_name()
>>>
>>> God, what messed up API.
>>
>> Yes, indeed. It is opposite to the usual object ownership rule that the code
>> fragment that asks for a handle has to release it.
>>
>> Usually it does not become obvious because often CONFIG_OF_DYNAMIC=n.
>> This disables all of_node refcounting completely so such bugs remain unnoticed.
>>
>>> Any chance we can make it a bit more sane and
>>> not drop the reference inside it instead?
>>
>> Well, if you want to change ~2000 files, test on all platforms and ask Linus
>> for agreement?
>
> It's not that bad, let's see what DT maintainers say to the patch I
> posted...
Thanks! Would make me more happy a well.
Nikolaus