[alsa-devel] [PATCH] ASoC: wm8962: Convert to devm_input_allocate_device()

[Leon Romanovsky]

On Sun, Apr 28, 2013 at 12:47 PM, Mark Brown <broonie at kernel.org> wrote:
> On Sun, Apr 28, 2013 at 08:00:29AM +0300, Leon Romanovsky wrote:
>> On Thu, Apr 25, 2013 at 3:52 PM, Mark Brown <broonie at kernel.org> wrote:
>
>> > This seems like a bug that should be fixed on the API side, it's really
>> > not what you'd expect a devm function to do, and if you are explicitly
>> > freeing a devm allocated object there's an expectation that you need to
>> > call a corresponding devm cleanup function.
>
>> I can't agree with you about the "expectation" - device memory can be in use.
>> This code will free memory after all references will be freed.
>> Additionally it is up-to developer to decide what to do if
>> input_register_device call failed.
>> According to the code base
>> (http://lxr.free-electrons.com/ident?i=input_free_device)
>> the patch is not correct.
>
> Right, but what I'm saying is that this is not how a devm_ API is
> expected to behave and is therefore at best error prone on two fronts -
> both due to the fact that you need to clean up explicitly even if the
> resource is not actually managed and also due to the fact that the
> regular free function is being used rather than a devm_ one when
> explicit deallocation is done.  Neither of these things is normal for a
> devm_ API.  The behaviour you're describing says that the managed
> function should actually be registration not allocation.
I think the reason of our misunderstanding is due to the name of
input_free_device call. From the code, it is device destroy function,
and the freeing itself done as an error handling of
input_register_device
(http://lxr.free-electrons.com/source/drivers/input/input.c#L2114).

How do you think we need to proceed? Do I need to send patches with
explicit call to input_free_device function?

--
Leon Romanovsky | Independent Linux Consultant
        www.leon.nu | leon at leon.nu