diff mbox series

[v3,02/24] gpio: of: assign and read the hog pointer atomically

Message ID 20240208095920.8035-3-brgl@bgdev.pl
State New
Headers show
Series gpio: rework locking and object life-time control | expand

Commit Message

Bartosz Golaszewski Feb. 8, 2024, 9:58 a.m. UTC 
From: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>

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>
---
 drivers/gpio/gpiolib-of.c | 4 ++--
 drivers/gpio/gpiolib.c    | 2 +-
 2 files changed, 3 insertions(+), 3 deletions(-)
diff mbox series

Patch

diff --git a/drivers/gpio/gpiolib-of.c b/drivers/gpio/gpiolib-of.c
index 77509aa19900..bd6b8702c790 100644
--- a/drivers/gpio/gpiolib-of.c
+++ b/drivers/gpio/gpiolib-of.c
@@ -800,7 +800,7 @@  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
 	}
 
@@ -848,7 +848,7 @@  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);
 }
 
diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c
index 181faeeceb3f..8ca9aebfa81f 100644
--- a/drivers/gpio/gpiolib.c
+++ b/drivers/gpio/gpiolib.c
@@ -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;
 	}