Re: [PATCH RESEND 4/6 v13] gpiolib: Fix default attributes for class

From: Grant Likely
Date: Fri Feb 15 2013 - 17:55:23 EST

On Tue, 15 Jan 2013 12:51:54 +0100, Roland Stigge <stigge@xxxxxxxxx> wrote:
> There is a race condition between creating a gpio or gpiochip device and adding
> default attributes. This patch fixes this by defining the default attributes as
> dev_attrs of the class. For this, it was necessary to create a separate
> gpiochip_class besides gpio_class.
> Signed-off-by: Roland Stigge <stigge@xxxxxxxxx>

Hi Roland,

Yup, that's a bug. Thanks for looking at this. Unfortunately creating a
new class creates a new problem because it changes the userspace ABI
(the gpiochip simlinks move to a different class directory).

Instead, I think the correct solution here is to use (struct device *)->groups
to add attributes to a device. Unfortunately that means that
create_device() won't work anymore. It does some useful setup work
though that I don't want to have to reproduce. You could create a
variant that also allows groups to be set, or you could factor out the
allocation/setup stuff so we can do an allocate/fixup/register sequence.


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