[PATCH v3 10/11] gpio: Leverage revocable for accessing struct gpio_chip

Tzung-Bi Shih
2026-02-13T09:31:32Z

Struct gpio_device now provides a revocable provider to the underlying
struct gpio_chip. Leverage revocable for accessing the struct
gpio_chip.

Signed-off-by: Tzung-Bi Shih <tzungbi@kernel.org>
---
v3:
- Change revocable API usages accordingly.

v2: https://lore.kernel.org/all/20260203061059.975605-11-tzungbi@kernel.org
- Separate from v1(a) for excluding gpio_chip_guard and combine v1(b).

v1(a):
- https://lore.kernel.org/all/20260116081036.352286-23-tzungbi@kernel.org
v1(b):
- https://lore.kernel.org/all/20260116081036.352286-19-tzungbi@kernel.org

drivers/gpio/gpiolib.c | 60 +++++++++++++-----------------------------
1 file changed, 18 insertions(+), 42 deletions(-)

diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c
index 34f2665a9311..2ba78add3417 100644
--- a/drivers/gpio/gpiolib.c
+++ b/drivers/gpio/gpiolib.c
@@ -338,7 +338,10 @@ EXPORT_SYMBOL(gpio_device_get_label);
*/
struct gpio_chip *gpio_device_get_chip(struct gpio_device *gdev)
{
- return rcu_dereference_check(gdev->chip, 1);
+ struct gpio_chip *gc;
+
+ revocable_try_access_with(gdev->chip_rp, gc);
+ return gc;
}
EXPORT_SYMBOL_GPL(gpio_device_get_chip);

@@ -556,9 +559,7 @@ static struct gpio_desc *gpio_name_to_desc(const char * const name)

list_for_each_entry_srcu(gdev, &gpio_devices, list,
srcu_read_lock_held(&gpio_devices_srcu)) {
- guard(srcu)(&gdev->srcu);
-
- gc = srcu_dereference(gdev->chip, &gdev->srcu);
+ revocable_try_access_with(gdev->chip_rp, gc);
if (!gc)
continue;

@@ -972,9 +973,7 @@ static void gpiochip_setup_devs(void)

list_for_each_entry_srcu(gdev, &gpio_devices, list,
srcu_read_lock_held(&gpio_devices_srcu)) {
- guard(srcu)(&gdev->srcu);
-
- gc = srcu_dereference(gdev->chip, &gdev->srcu);
+ revocable_try_access_with(gdev->chip_rp, gc);
if (!gc) {
dev_err(&gdev->dev, "Underlying GPIO chip is gone\n");
continue;
@@ -1378,11 +1377,11 @@ struct gpio_device *gpio_device_find(const void *data,
if (!device_is_registered(&gdev->dev))
continue;

- guard(srcu)(&gdev->srcu);
-
- gc = srcu_dereference(gdev->chip, &gdev->srcu);
+ revocable_try_access_with(gdev->chip_rp, gc);
+ if (!gc)
+ continue;

- if (gc && match(gc, data))
+ if (match(gc, data))
return gpio_device_get(gdev);
}

@@ -3310,18 +3309,10 @@ static int gpio_chip_get_value(struct gpio_chip *gc, const struct gpio_desc *des

static int gpiod_get_raw_value_commit(const struct gpio_desc *desc)
{
- struct gpio_device *gdev;
struct gpio_chip *gc;
int value;

- /* FIXME Unable to use gpio_chip_guard due to const desc. */
- gdev = desc->gdev;
-
- guard(srcu)(&gdev->srcu);
-
- gc = srcu_dereference(gdev->chip, &gdev->srcu);
- if (!gc)
- return -ENODEV;
+ revocable_try_access_or_return(desc->gdev->chip_rp, gc);

value = gpio_chip_get_value(gc, desc);
value = value < 0 ? value : !!value;
@@ -3360,9 +3351,10 @@ static int gpio_chip_get_multiple(struct gpio_chip *gc,
/* The 'other' chip must be protected with its GPIO device's SRCU. */
static bool gpio_device_chip_cmp(struct gpio_device *gdev, struct gpio_chip *gc)
{
- guard(srcu)(&gdev->srcu);
+ struct gpio_chip *chip;

- return gc == srcu_dereference(gdev->chip, &gdev->srcu);
+ revocable_try_access_with(gdev->chip_rp, chip);
+ return chip ? chip == gc : false;
}

int gpiod_get_array_value_complex(bool raw, bool can_sleep,
@@ -3385,11 +3377,7 @@ int gpiod_get_array_value_complex(bool raw, bool can_sleep,
if (!can_sleep)
WARN_ON(array_info->gdev->can_sleep);

- guard(srcu)(&array_info->gdev->srcu);
- gc = srcu_dereference(array_info->gdev->chip,
- &array_info->gdev->srcu);
- if (!gc)
- return -ENODEV;
+ revocable_try_access_or_return(array_info->gdev->chip_rp, gc);

ret = gpio_chip_get_multiple(gc, array_info->get_mask,
value_bitmap);
@@ -3726,11 +3714,7 @@ int gpiod_set_array_value_complex(bool raw, bool can_sleep,
return -EPERM;
}

- guard(srcu)(&array_info->gdev->srcu);
- gc = srcu_dereference(array_info->gdev->chip,
- &array_info->gdev->srcu);
- if (!gc)
- return -ENODEV;
+ revocable_try_access_or_return(array_info->gdev->chip_rp, gc);

if (!raw && !bitmap_empty(array_info->invert_mask, array_size))
bitmap_xor(value_bitmap, value_bitmap,
@@ -4024,7 +4008,6 @@ EXPORT_SYMBOL_GPL(gpiod_is_shared);
*/
int gpiod_to_irq(const struct gpio_desc *desc)
{
- struct gpio_device *gdev;
struct gpio_chip *gc;
int offset;
int ret;
@@ -4033,12 +4016,7 @@ int gpiod_to_irq(const struct gpio_desc *desc)
if (ret <= 0)
return -EINVAL;

- gdev = desc->gdev;
- /* FIXME Cannot use gpio_chip_guard due to const desc. */
- guard(srcu)(&gdev->srcu);
- gc = srcu_dereference(gdev->chip, &gdev->srcu);
- if (!gc)
- return -ENODEV;
+ revocable_try_access_or_return(desc->gdev->chip_rp, gc);

offset = gpiod_hwgpio(desc);
if (gc->to_irq) {
@@ -5413,9 +5391,7 @@ static int gpiolib_seq_show(struct seq_file *s, void *v)
if (priv->newline)
seq_putc(s, '\n');

- guard(srcu)(&gdev->srcu);
-
- gc = srcu_dereference(gdev->chip, &gdev->srcu);
+ revocable_try_access_with(gdev->chip_rp, gc);
if (!gc) {
seq_printf(s, "%s: (dangling chip)\n", dev_name(&gdev->dev));
return 0;
--
2.53.0.310.g728cabbaf7-goog