[PATCH] gpio: msc313: remove kcalloc

[PATCH] gpio: msc313: remove kcalloc

[Rosen Penev]

Use a flexible array member to combine kzalloc and kcalloc.

Signed-off-by: Rosen Penev <rosenp@gmail.com>
---
 drivers/gpio/gpio-msc313.c | 8 ++------
 1 file changed, 2 insertions(+), 6 deletions(-)

diff --git a/drivers/gpio/gpio-msc313.c b/drivers/gpio/gpio-msc313.c
index 7345afdc78de..de3e6da2a089 100644
--- a/drivers/gpio/gpio-msc313.c
+++ b/drivers/gpio/gpio-msc313.c
@@ -483,7 +483,7 @@ MSC313_GPIO_CHIPDATA(ssd20xd);
 struct msc313_gpio {
 	void __iomem *base;
 	const struct msc313_gpio_data *gpio_data;
-	u8 *saved;
+	u8 saved[];
 };
 
 static int msc313_gpio_set(struct gpio_chip *chip, unsigned int offset, int value)
@@ -631,16 +631,12 @@ static int msc313_gpio_probe(struct platform_device *pdev)
 	if (!parent_domain)
 		return -ENODEV;
 
-	gpio = devm_kzalloc(dev, sizeof(*gpio), GFP_KERNEL);
+	gpio = devm_kzalloc(dev, struct_size(gpio, saved, match_data->num), GFP_KERNEL);
 	if (!gpio)
 		return -ENOMEM;
 
 	gpio->gpio_data = match_data;
 
-	gpio->saved = devm_kcalloc(dev, gpio->gpio_data->num, sizeof(*gpio->saved), GFP_KERNEL);
-	if (!gpio->saved)
-		return -ENOMEM;
-
 	gpio->base = devm_platform_ioremap_resource(pdev, 0);
 	if (IS_ERR(gpio->base))
 		return PTR_ERR(gpio->base);
-- 
2.53.0

Re: [PATCH] gpio: msc313: remove kcalloc

[Daniel Palmer]

Hi Rosen,

On Sun, 8 Mar 2026 at 11:15, Rosen Penev <rosenp@gmail.com> wrote:
>
> Use a flexible array member to combine kzalloc and kcalloc.

Thanks for the patch. This looks good to me. If I get time I will
build and test this but I can see why it shouldn't work.

Acked-by: Daniel Palmer <daniel@thingy.jp>

Re: [PATCH] gpio: msc313: remove kcalloc

[Linus Walleij]

On Sun, Mar 8, 2026 at 3:15 AM Rosen Penev <rosenp@gmail.com> wrote:

> Use a flexible array member to combine kzalloc and kcalloc.
>
> Signed-off-by: Rosen Penev <rosenp@gmail.com>
(...)
>  struct msc313_gpio {
>         void __iomem *base;
>         const struct msc313_gpio_data *gpio_data;

Do you wanna add:

const unsigned int saved_size;

> -       u8 *saved;
> +       u8 saved[];

u8 saved[] __counted_by(saved_size);

>  static int msc313_gpio_set(struct gpio_chip *chip, unsigned int offset, int value)
> @@ -631,16 +631,12 @@ static int msc313_gpio_probe(struct platform_device *pdev)
>         if (!parent_domain)
>                 return -ENODEV;
>
> -       gpio = devm_kzalloc(dev, sizeof(*gpio), GFP_KERNEL);
> +       gpio = devm_kzalloc(dev, struct_size(gpio, saved, match_data->num), GFP_KERNEL);
>         if (!gpio)
>                 return -ENOMEM;

gpio->saved_size = match_data->num;

I know it takes some bytes more but it feels way safer.

Yours,
Linus Walleij

Re: [PATCH] gpio: msc313: remove kcalloc

[Rosen Penev]

On Sun, Mar 8, 2026 at 5:06 PM Linus Walleij <linusw@kernel.org> wrote:
>
> On Sun, Mar 8, 2026 at 3:15 AM Rosen Penev <rosenp@gmail.com> wrote:
>
> > Use a flexible array member to combine kzalloc and kcalloc.
> >
> > Signed-off-by: Rosen Penev <rosenp@gmail.com>
> (...)
> >  struct msc313_gpio {
> >         void __iomem *base;
> >         const struct msc313_gpio_data *gpio_data;
>
> Do you wanna add:
>
> const unsigned int saved_size;
So in the code there's

for (i = 0; i < gpio->gpio_data->num; i++)

which is equivalent to match->num.

__counted_by doesn't support pointers AFAIK.
>
> > -       u8 *saved;
> > +       u8 saved[];
>
> u8 saved[] __counted_by(saved_size);
>
> >  static int msc313_gpio_set(struct gpio_chip *chip, unsigned int offset, int value)
> > @@ -631,16 +631,12 @@ static int msc313_gpio_probe(struct platform_device *pdev)
> >         if (!parent_domain)
> >                 return -ENODEV;
> >
> > -       gpio = devm_kzalloc(dev, sizeof(*gpio), GFP_KERNEL);
> > +       gpio = devm_kzalloc(dev, struct_size(gpio, saved, match_data->num), GFP_KERNEL);
> >         if (!gpio)
> >                 return -ENOMEM;
>
> gpio->saved_size = match_data->num;
>
> I know it takes some bytes more but it feels way safer.
>
> Yours,
> Linus Walleij

Re: [PATCH] gpio: msc313: remove kcalloc

[Gustavo A. R. Silva]

On 3/9/26 10:27, Rosen Penev wrote:
> On Sun, Mar 8, 2026 at 5:06 PM Linus Walleij <linusw@kernel.org> wrote:
>>
>> On Sun, Mar 8, 2026 at 3:15 AM Rosen Penev <rosenp@gmail.com> wrote:
>>
>>> Use a flexible array member to combine kzalloc and kcalloc.
>>>
>>> Signed-off-by: Rosen Penev <rosenp@gmail.com>
>> (...)
>>>   struct msc313_gpio {
>>>          void __iomem *base;
>>>          const struct msc313_gpio_data *gpio_data;
>>
>> Do you wanna add:
>>
>> const unsigned int saved_size;
> So in the code there's
> 
> for (i = 0; i < gpio->gpio_data->num; i++)
> 
> which is equivalent to match->num.
> 
> __counted_by doesn't support pointers AFAIK.

We actually have __counted_by_ptr().

-Gustavo

Re: [PATCH] gpio: msc313: remove kcalloc

[Bartosz Golaszewski]

On Mon, Mar 9, 2026 at 2:27 AM Rosen Penev <rosenp@gmail.com> wrote:
>
> On Sun, Mar 8, 2026 at 5:06 PM Linus Walleij <linusw@kernel.org> wrote:
> >
> > On Sun, Mar 8, 2026 at 3:15 AM Rosen Penev <rosenp@gmail.com> wrote:
> >
> > > Use a flexible array member to combine kzalloc and kcalloc.
> > >
> > > Signed-off-by: Rosen Penev <rosenp@gmail.com>
> > (...)
> > >  struct msc313_gpio {
> > >         void __iomem *base;
> > >         const struct msc313_gpio_data *gpio_data;
> >
> > Do you wanna add:
> >
> > const unsigned int saved_size;
> So in the code there's
>
> for (i = 0; i < gpio->gpio_data->num; i++)
>
> which is equivalent to match->num.
>
> __counted_by doesn't support pointers AFAIK.
> >

This is a regular flexible array of u8. It should work fine with
__counted_by and I too am in favor of using it as it has become
standard for flexible arrays.

Bart

Re: [PATCH] gpio: msc313: remove kcalloc

[Rosen Penev]

On Mon, Mar 9, 2026 at 2:03 AM Bartosz Golaszewski <brgl@kernel.org> wrote:
>
> On Mon, Mar 9, 2026 at 2:27 AM Rosen Penev <rosenp@gmail.com> wrote:
> >
> > On Sun, Mar 8, 2026 at 5:06 PM Linus Walleij <linusw@kernel.org> wrote:
> > >
> > > On Sun, Mar 8, 2026 at 3:15 AM Rosen Penev <rosenp@gmail.com> wrote:
> > >
> > > > Use a flexible array member to combine kzalloc and kcalloc.
> > > >
> > > > Signed-off-by: Rosen Penev <rosenp@gmail.com>
> > > (...)
> > > >  struct msc313_gpio {
> > > >         void __iomem *base;
> > > >         const struct msc313_gpio_data *gpio_data;
> > >
> > > Do you wanna add:
> > >
> > > const unsigned int saved_size;
> > So in the code there's
> >
> > for (i = 0; i < gpio->gpio_data->num; i++)
> >
> > which is equivalent to match->num.
> >
> > __counted_by doesn't support pointers AFAIK.
> > >
>
> This is a regular flexible array of u8. It should work fine with
> __counted_by and I too am in favor of using it as it has become
> standard for flexible arrays.
That requires adding an extra variable in the struct.
>
> Bart

Re: [PATCH] gpio: msc313: remove kcalloc

[Bartosz Golaszewski]

On Mon, Mar 9, 2026 at 11:00 PM Rosen Penev <rosenp@gmail.com> wrote:
>
> On Mon, Mar 9, 2026 at 2:03 AM Bartosz Golaszewski <brgl@kernel.org> wrote:
> >
> > On Mon, Mar 9, 2026 at 2:27 AM Rosen Penev <rosenp@gmail.com> wrote:
> > >
> > > On Sun, Mar 8, 2026 at 5:06 PM Linus Walleij <linusw@kernel.org> wrote:
> > > >
> > > > On Sun, Mar 8, 2026 at 3:15 AM Rosen Penev <rosenp@gmail.com> wrote:
> > > >
> > > > > Use a flexible array member to combine kzalloc and kcalloc.
> > > > >
> > > > > Signed-off-by: Rosen Penev <rosenp@gmail.com>
> > > > (...)
> > > > >  struct msc313_gpio {
> > > > >         void __iomem *base;
> > > > >         const struct msc313_gpio_data *gpio_data;
> > > >
> > > > Do you wanna add:
> > > >
> > > > const unsigned int saved_size;
> > > So in the code there's
> > >
> > > for (i = 0; i < gpio->gpio_data->num; i++)
> > >
> > > which is equivalent to match->num.
> > >
> > > __counted_by doesn't support pointers AFAIK.
> > > >
> >
> > This is a regular flexible array of u8. It should work fine with
> > __counted_by and I too am in favor of using it as it has become
> > standard for flexible arrays.
> That requires adding an extra variable in the struct.

That's ok, it's negligible and provides tangible advantages.

Please do the same for your other patches.

Bart