Re: [PATCH v7 07/20] gpiolib: cdev: support GPIO_V2_GET_LINE_IOCTL and GPIO_V2_LINE_GET_VALUES_IOCTL

[Bartosz Golaszewski <bgolaszewski@xxxxxxxxxxxx>]

On Wed, Sep 9, 2020 at 11:24 AM Kent Gibson <warthog618@xxxxxxxxx> wrote:
>
> On Sat, Sep 05, 2020 at 09:35:36PM +0800, Kent Gibson wrote:
> > Add support for requesting lines using the GPIO_V2_GET_LINE_IOCTL, and
> > returning their current values using GPIO_V2_LINE_GET_VALUES_IOCTL.
> >
> > The struct linereq implementation is based on the v1 struct linehandle
> > implementation.
> >
> > Signed-off-by: Kent Gibson <warthog618@xxxxxxxxx>
> > ---
> >
>
> [snip]
>
> >               if (copy_from_user(&offset, ip, sizeof(offset)))
> >                       return -EFAULT;
> > @@ -1104,6 +1505,25 @@ int gpiolib_cdev_register(struct gpio_device *gdev, dev_t devt)
> >                MAJOR(devt), gdev->id);
> >
> >       return 0;
> > +     /*
> > +      * array sizes must ensure 64-bit alignment and not create holes in
> > +      * the struct packing.
> > +      */
> > +     BUILD_BUG_ON(IS_ALIGNED(GPIO_V2_LINES_MAX, 2));
> > +     BUILD_BUG_ON(IS_ALIGNED(GPIO_MAX_NAME_SIZE, 8));
> > +
> > +     /*
> > +      * check that uAPI structs are 64-bit aligned for 32/64-bit
> > +      * compatibility
> > +      */
> > +     BUILD_BUG_ON(IS_ALIGNED(sizeof(struct gpio_v2_line_attribute), 8));
> > +     BUILD_BUG_ON(IS_ALIGNED(sizeof(struct gpio_v2_line_config_attribute), 8));
> > +     BUILD_BUG_ON(IS_ALIGNED(sizeof(struct gpio_v2_line_config), 8));
> > +     BUILD_BUG_ON(IS_ALIGNED(sizeof(struct gpio_v2_line_request), 8));
> > +     BUILD_BUG_ON(IS_ALIGNED(sizeof(struct gpio_v2_line_info), 8));
> > +     BUILD_BUG_ON(IS_ALIGNED(sizeof(struct gpio_v2_line_info_changed), 8));
> > +     BUILD_BUG_ON(IS_ALIGNED(sizeof(struct gpio_v2_line_event), 8));
> > +     BUILD_BUG_ON(IS_ALIGNED(sizeof(struct gpio_v2_line_values), 8));
> >  }
> >
>
> A couple of things here - these should all be !IS_ALIGNED.
> And the BUILD_BUG_ON gets compiled out, and so doesn't fail, if they are
> after the return.
>
> How would you like that fixed - v8 or a patch once v7 is in?
>
> Cheers,
> Kent.

v8 please. Why is it compiled out though? Does it need some config option?

Bart