[PATCH] gpiolib: Mark gpio_devt, gpiolib_initialized and gpio_stub_drv as __ro_after_init

[PATCH] gpiolib: Mark gpio_devt, gpiolib_initialized and gpio_stub_drv as __ro_after_init

[Len Bao]

The 'gpio_devt' and 'gpiolib_initialized' variables are initialized only
during the init phase in the 'gpiolib_dev_init' function and never
changed. So, mark these as __ro_after_init.

The 'gpio_stub_drv' variable is initialized only in the declaration and
never changed. So, this variable could be 'const', but using the
'driver_register' and 'driver_unregister' functions discards the 'const'
qualifier. Therefore, as an alternative, mark it as a __ro_after_init.

Signed-off-by: Len Bao <len.bao@gmx.us>
---
 drivers/gpio/gpiolib.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c
index 1e6dce430..6b2bc0b78 100644
--- a/drivers/gpio/gpiolib.c
+++ b/drivers/gpio/gpiolib.c
@@ -55,7 +55,7 @@
 
 /* Device and char device-related information */
 static DEFINE_IDA(gpio_ida);
-static dev_t gpio_devt;
+static dev_t gpio_devt __ro_after_init;
 #define GPIO_DEV_MAX 256 /* 256 GPIO chip devices supported */
 
 static int gpio_bus_match(struct device *dev, const struct device_driver *drv)
@@ -114,7 +114,7 @@ static int gpiochip_irqchip_init_hw(struct gpio_chip *gc);
 static int gpiochip_irqchip_init_valid_mask(struct gpio_chip *gc);
 static void gpiochip_irqchip_free_valid_mask(struct gpio_chip *gc);
 
-static bool gpiolib_initialized;
+static bool gpiolib_initialized __ro_after_init;
 
 const char *gpiod_get_label(struct gpio_desc *desc)
 {
@@ -5340,7 +5340,7 @@ EXPORT_SYMBOL_GPL(gpiod_put_array);
  * gpio_device of the GPIO chip with the firmware node and then simply
  * bind it to this stub driver.
  */
-static struct device_driver gpio_stub_drv = {
+static struct device_driver gpio_stub_drv __ro_after_init = {
 	.name = "gpio_stub_drv",
 	.bus = &gpio_bus_type,
 };
-- 
2.43.0

Re: [PATCH] gpiolib: Mark gpio_devt, gpiolib_initialized and gpio_stub_drv as __ro_after_init

[Linus Walleij]

Hi Len,

thanks for your patch!

On Sat, May 16, 2026 at 12:58 PM Len Bao <len.bao@gmx.us> wrote:

> The 'gpio_devt' and 'gpiolib_initialized' variables are initialized only
> during the init phase in the 'gpiolib_dev_init' function and never
> changed. So, mark these as __ro_after_init.
>
> The 'gpio_stub_drv' variable is initialized only in the declaration and
> never changed. So, this variable could be 'const', but using the
> 'driver_register' and 'driver_unregister' functions discards the 'const'
> qualifier. Therefore, as an alternative, mark it as a __ro_after_init.
>
> Signed-off-by: Len Bao <len.bao@gmx.us>

Patches like this should be CC to linux-hardening.

Anyways it looks good to me!
Reviewed-by: Linus Walleij <linusw@kernel.org>

Yours,
Linus Walleij

Re: [PATCH] gpiolib: Mark gpio_devt, gpiolib_initialized and gpio_stub_drv as __ro_after_init

[Bartosz Golaszewski]

On Sat, 16 May 2026 10:57:34 +0000, Len Bao wrote:
> The 'gpio_devt' and 'gpiolib_initialized' variables are initialized only
> during the init phase in the 'gpiolib_dev_init' function and never
> changed. So, mark these as __ro_after_init.
> 
> The 'gpio_stub_drv' variable is initialized only in the declaration and
> never changed. So, this variable could be 'const', but using the
> 'driver_register' and 'driver_unregister' functions discards the 'const'
> qualifier. Therefore, as an alternative, mark it as a __ro_after_init.
> 
> [...]

Applied, thanks!

[1/1] gpiolib: Mark gpio_devt, gpiolib_initialized and gpio_stub_drv as __ro_after_init
      https://git.kernel.org/brgl/c/b12e12ee4138e30d786eda02223e87044c989bb1

Best regards,
-- 
Bartosz Golaszewski <bartosz.golaszewski@oss.qualcomm.com>

Re: [PATCH] gpiolib: Mark gpio_devt, gpiolib_initialized and gpio_stub_drv as __ro_after_init

[Len Bao]

Hi Linus,

On Mon, May 25, 2026 at 10:10:02AM +0200, Linus Walleij wrote:
> Hi Len,
> 
> thanks for your patch!
> 
> On Sat, May 16, 2026 at 12:58 PM Len Bao <len.bao@gmx.us> wrote:
> 
> > The 'gpio_devt' and 'gpiolib_initialized' variables are initialized only
> > during the init phase in the 'gpiolib_dev_init' function and never
> > changed. So, mark these as __ro_after_init.
> >
> > The 'gpio_stub_drv' variable is initialized only in the declaration and
> > never changed. So, this variable could be 'const', but using the
> > 'driver_register' and 'driver_unregister' functions discards the 'const'
> > qualifier. Therefore, as an alternative, mark it as a __ro_after_init.
> >
> > Signed-off-by: Len Bao <len.bao@gmx.us>
> 
> Patches like this should be CC to linux-hardening.

Ok, next time I will CC to linux-hardening. Thanks for the guidance.

> Anyways it looks good to me!
> Reviewed-by: Linus Walleij <linusw@kernel.org>

Thanks for your time to look at this.

Regards,
Len Bao

> Yours,
> Linus Walleij