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gpio: don't let lockdep complain about inherently dangerous RCU usage

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There are two legacy, deprecated functions - gpiod_to_chip() and
gpio_device_get_chip() - that still have users in tree. They return the
address of the SRCU-protected chip outside of the read-only critical
sections. They are inherently dangerous and the users should convert to
safer alternatives. Let's explicitly silence lockdep warnings by using
rcu_dereference_check(ptr, 1). While at it: reuse
gpio_device_get_chip() in gpiod_to_chip().

Fixes: d83cee3d2b ("gpio: protect the pointer to gpio_chip in gpio_device with SRCU")
Reported-by: kernel test robot <oliver.sang@intel.com>
Closes: https://lore.kernel.org/oe-lkp/202402122234.d85cca9b-lkp@intel.com
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
This commit is contained in:
Bartosz Golaszewski
2024-02-14 09:44:19 +01:00
parent d82b9e0887
commit 0d7fa0eda4
1 changed files with 3 additions and 2 deletions
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5
drivers/gpio/gpiolib.c
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@@ -221,7 +221,8 @@ struct gpio_chip *gpiod_to_chip(const struct gpio_desc *desc)
{
if (!desc)
return NULL;
return rcu_dereference(desc->gdev->chip);
return gpio_device_get_chip(desc->gdev);
}
EXPORT_SYMBOL_GPL(gpiod_to_chip);
@@ -291,7 +292,7 @@ EXPORT_SYMBOL(gpio_device_get_label);
*/
struct gpio_chip *gpio_device_get_chip(struct gpio_device *gdev)
{
return rcu_dereference(gdev->chip);
return rcu_dereference_check(gdev->chip, 1);
}
EXPORT_SYMBOL_GPL(gpio_device_get_chip);