On Tue, Mar 24, 2026 at 2:16 AM Bartosz Golaszewski <[email protected]> wrote:
>
> On Mon, 23 Mar 2026 17:43:00 +0100, Rosen Penev <[email protected]> said:
> > On Mon, Mar 23, 2026 at 3:00 AM Bartosz Golaszewski <[email protected]> wrote:
> >>
> >> On Sat, Mar 21, 2026 at 12:00 AM Rosen Penev <[email protected]> wrote:
> >> >
> >> > >
> >> > > static int gpio_mockup_probe(struct platform_device *pdev)
> >> > > {
> >> > > ...
> >> > > u16 ngpio;
> >> > > ...
> >> > > rv = device_property_read_u16(dev, "nr-gpios", &ngpio);
> >> > > ...
> >> > > gc->ngpio = ngpio;
> >> > > ...
> >> > > chip->lines = devm_kcalloc(dev, gc->ngpio,
> >> > > sizeof(*chip->lines), GFP_KERNEL);
> >> > >
> >> > > But this begs the question: why add nr_lines when ngpio is already part
> >> > > of the struct:
> >> > Maintainers for some inexplicable reason want an extra variable for
> >> > __counted_by works.
> >>
> >> I believe what Kees means here is: you can use ngpio for __counted_by()
> >> like so:
> >>
> >> __counted_by(gc.ngpio)
> > __counted_by doesn't support nested variables like that.
> >
> > drivers/gpio/gpio-mockup.c:59:61: error: ‘gc’ undeclared here (not in
> > a function)
> > 59 | struct gpio_mockup_line_status lines[]
> > __counted_by(gc.ngpio);
>
> The following spin on your patch builds fine for me:
>
> diff --git a/drivers/gpio/gpio-mockup.c b/drivers/gpio/gpio-mockup.c
> index a7d69f3835c1e..9427ab8c45f73 100644
> --- a/drivers/gpio/gpio-mockup.c
> +++ b/drivers/gpio/gpio-mockup.c
> @@ -52,10 +52,10 @@ struct gpio_mockup_line_status {
>
> struct gpio_mockup_chip {
> struct gpio_chip gc;
> - struct gpio_mockup_line_status *lines;
> struct irq_domain *irq_sim_domain;
> struct dentry *dbg_dir;
> struct mutex lock;
> + struct gpio_mockup_line_status lines[] __counted_by(gc.ngpio);
You're using an older compiler. This does not work at all.
* Optional: only supported since gcc >= 15
* Optional: only supported since clang >= 18
> };
>
> struct gpio_mockup_dbgfs_private {
> @@ -436,15 +436,16 @@ static int gpio_mockup_probe(struct platform_device
> *pdev)
> if (rv)
> name = dev_name(dev);
>
> - chip = devm_kzalloc(dev, sizeof(*chip), GFP_KERNEL);
> + chip = devm_kzalloc(dev, struct_size(chip, lines, ngpio), GFP_KERNEL);
> if (!chip)
> return -ENOMEM;
>
> - mutex_init(&chip->lock);
> -
> gc = &chip->gc;
> - gc->base = base;
> gc->ngpio = ngpio;
> + gc->base = base;
> +
> + mutex_init(&chip->lock);
> +
> gc->label = name;
> gc->owner = THIS_MODULE;
> gc->parent = dev;
> @@ -460,11 +461,6 @@ static int gpio_mockup_probe(struct platform_device
> *pdev)
> gc->request = gpio_mockup_request;
> gc->free = gpio_mockup_free;
>
> - chip->lines = devm_kcalloc(dev, gc->ngpio,
> - sizeof(*chip->lines), GFP_KERNEL);
> - if (!chip->lines)
> - return -ENOMEM;
> -
> for (i = 0; i < gc->ngpio; i++)
> chip->lines[i].dir = GPIO_LINE_DIRECTION_IN;
>
> Bart
