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gpio: of: assign and read the hog pointer atomically

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The device nodes representing GPIO hogs cannot be deleted without
unregistering the GPIO chip so there's no need to serialize their access.
However we must ensure that users can get the right address so write and
read it atomically.

Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Acked-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
This commit is contained in:
Bartosz Golaszewski
2024-01-05 13:12:45 +01:00
parent e348544f79
commit 8ce6fd81a4
2 changed files with 3 additions and 3 deletions
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4
drivers/gpio/gpiolib-of.c
View File

@@ -801,7 +801,7 @@ static int of_gpiochip_add_hog(struct gpio_chip *chip, struct device_node *hog)
return ret;
#ifdef CONFIG_OF_DYNAMIC
desc->hog = hog;
WRITE_ONCE(desc->hog, hog);
#endif
}
@@ -849,7 +849,7 @@ static void of_gpiochip_remove_hog(struct gpio_chip *chip,
struct gpio_desc *desc;
for_each_gpio_desc_with_flag(chip, desc, FLAG_IS_HOGGED)
if (desc->hog == hog)
if (READ_ONCE(desc->hog) == hog)
gpiochip_free_own_desc(desc);
}

2
drivers/gpio/gpiolib.c
View File

@@ -2330,7 +2330,7 @@ static bool gpiod_free_commit(struct gpio_desc *desc)
clear_bit(FLAG_EDGE_FALLING, &desc->flags);
clear_bit(FLAG_IS_HOGGED, &desc->flags);
#ifdef CONFIG_OF_DYNAMIC
desc->hog = NULL;
WRITE_ONCE(desc->hog, NULL);
#endif
ret = true;
}