Re: [PATCH] gpio: Fix lockdep warnings in gpiolib_{cdev,sysfs}_register()

[Marek Szyprowski <m.szyprowski@samsung.com>]

On 28.02.2026 14:14, Tzung-Bi Shih wrote:
> A lockdep warning is reported in gpiolib-cdev driver:
>
>    WARNING: drivers/gpio/gpiolib-cdev.c:2735 at
>    gpiolib_cdev_register+0x114/0x140, CPU#1: swapper/0/1
>    Modules linked in:
>    CPU: 1 UID: 0 PID: 1 Comm: swapper/0 Not tainted
>    7.0.0-rc1-next-20260227-00065-g6af4b9cfeded #12259 PREEMPT
>    Hardware name: Samsung Exynos (Flattened Device Tree)
>    Call trace:
>      unwind_backtrace from show_stack+0x10/0x14
>      show_stack from dump_stack_lvl+0x68/0x88
>      dump_stack_lvl from __warn+0x94/0x210
>      __warn from warn_slowpath_fmt+0x1b0/0x1bc
>      warn_slowpath_fmt from gpiolib_cdev_register+0x114/0x140
>      gpiolib_cdev_register from gpiochip_setup_dev+0x4c/0xd0
>      gpiochip_setup_dev from gpiochip_add_data_with_key+0x960/0xad4
>      gpiochip_add_data_with_key from devm_gpiochip_add_data_with_key+0x20/0x5c
>
> This is because the SRCU wasn't held in gpiolib_cdev_register() when the
> caller is from gpiochip_add_data_with_key() instead of
> gpiochip_setup_devs().  gpiochip_sysfs_register() shares the similar
> concern.
>
> Given that both gpiolib_cdev_register() and gpiochip_sysfs_register()
> are only called from gpiolib but no external users.  Remove the lockdep
> checks to fix the warnings.
>
> Reported-by: Marek Szyprowski <m.szyprowski@samsung.com>
> Closes: https://lore.kernel.org/all/506ce9b3-d492-4fce-9d02-330e411911e2@samsung.com/
> Fixes: cf674f1a0c98 ("gpio: Ensure struct gpio_chip for gpiochip_setup_dev()")
> Signed-off-by: Tzung-Bi Shih <tzungbi@kernel.org>

Tested-by: Marek Szyprowski <m.szyprowski@samsung.com>

> ---
>   drivers/gpio/gpiolib-cdev.c  | 2 --
>   drivers/gpio/gpiolib-sysfs.c | 2 --
>   2 files changed, 4 deletions(-)
>
> diff --git a/drivers/gpio/gpiolib-cdev.c b/drivers/gpio/gpiolib-cdev.c
> index 7ebdb4993a74..f36b7c06996d 100644
> --- a/drivers/gpio/gpiolib-cdev.c
> +++ b/drivers/gpio/gpiolib-cdev.c
> @@ -2732,8 +2732,6 @@ int gpiolib_cdev_register(struct gpio_chip *gc, dev_t devt)
>   	struct gpio_device *gdev = gc->gpiodev;
>   	int ret;
>   
> -	lockdep_assert_held(&gdev->srcu);
> -
>   	cdev_init(&gdev->chrdev, &gpio_fileops);
>   	gdev->chrdev.owner = THIS_MODULE;
>   	gdev->dev.devt = MKDEV(MAJOR(devt), gdev->id);
> diff --git a/drivers/gpio/gpiolib-sysfs.c b/drivers/gpio/gpiolib-sysfs.c
> index 748a3eb1bf35..fc06b0c2881b 100644
> --- a/drivers/gpio/gpiolib-sysfs.c
> +++ b/drivers/gpio/gpiolib-sysfs.c
> @@ -990,8 +990,6 @@ int gpiochip_sysfs_register(struct gpio_chip *gc)
>   	struct device *parent;
>   	int err;
>   
> -	lockdep_assert_held(&gdev->srcu);
> -
>   	/*
>   	 * Many systems add gpio chips for SOC support very early,
>   	 * before driver model support is available.  In those cases we

Best regards
-- 
Marek Szyprowski, PhD
Samsung R&D Institute Poland