[PATCH v3 04/11] gpio: Ensure struct gpio_chip for gpiochip_setup_dev()

Tzung-Bi Shih posted 11 patches 1 month, 2 weeks ago
[PATCH v3 04/11] gpio: Ensure struct gpio_chip for gpiochip_setup_dev()
Posted by Tzung-Bi Shih 1 month, 2 weeks ago
Ensure struct gpio_chip for gpiochip_setup_dev().  This eliminates a few
checks for struct gpio_chip.

Signed-off-by: Tzung-Bi Shih <tzungbi@kernel.org>
---
v3:
- Pass struct gpio_chip * only.

v2: https://lore.kernel.org/all/20260203061059.975605-5-tzungbi@kernel.org
- No changes.

v1: https://lore.kernel.org/all/20260116081036.352286-10-tzungbi@kernel.org

 drivers/gpio/gpiolib-cdev.c  | 12 ++----------
 drivers/gpio/gpiolib-cdev.h  |  2 +-
 drivers/gpio/gpiolib-sysfs.c | 13 +++----------
 drivers/gpio/gpiolib-sysfs.h |  4 ++--
 drivers/gpio/gpiolib.c       | 24 +++++++++++++++++-------
 5 files changed, 25 insertions(+), 30 deletions(-)

diff --git a/drivers/gpio/gpiolib-cdev.c b/drivers/gpio/gpiolib-cdev.c
index 2adc3c070908..b028198adba8 100644
--- a/drivers/gpio/gpiolib-cdev.c
+++ b/drivers/gpio/gpiolib-cdev.c
@@ -2782,9 +2782,9 @@ static const struct file_operations gpio_fileops = {
 #endif
 };
 
-int gpiolib_cdev_register(struct gpio_device *gdev, dev_t devt)
+int gpiolib_cdev_register(struct gpio_chip *gc, dev_t devt)
 {
-	struct gpio_chip *gc;
+	struct gpio_device *gdev = gc->gpiodev;
 	int ret;
 
 	cdev_init(&gdev->chrdev, &gpio_fileops);
@@ -2802,14 +2802,6 @@ int gpiolib_cdev_register(struct gpio_device *gdev, dev_t devt)
 		return ret;
 	}
 
-	guard(srcu)(&gdev->srcu);
-	gc = srcu_dereference(gdev->chip, &gdev->srcu);
-	if (!gc) {
-		cdev_device_del(&gdev->chrdev, &gdev->dev);
-		destroy_workqueue(gdev->line_state_wq);
-		return -ENODEV;
-	}
-
 	gpiochip_dbg(gc, "added GPIO chardev (%d:%d)\n", MAJOR(devt), gdev->id);
 
 	return 0;
diff --git a/drivers/gpio/gpiolib-cdev.h b/drivers/gpio/gpiolib-cdev.h
index b42644cbffb8..4a9cb3335d99 100644
--- a/drivers/gpio/gpiolib-cdev.h
+++ b/drivers/gpio/gpiolib-cdev.h
@@ -7,7 +7,7 @@
 
 struct gpio_device;
 
-int gpiolib_cdev_register(struct gpio_device *gdev, dev_t devt);
+int gpiolib_cdev_register(struct gpio_chip *gc, dev_t devt);
 void gpiolib_cdev_unregister(struct gpio_device *gdev);
 
 #endif /* GPIOLIB_CDEV_H */
diff --git a/drivers/gpio/gpiolib-sysfs.c b/drivers/gpio/gpiolib-sysfs.c
index 97e269f30945..3fdcfa0c7d42 100644
--- a/drivers/gpio/gpiolib-sysfs.c
+++ b/drivers/gpio/gpiolib-sysfs.c
@@ -978,10 +978,10 @@ void gpiod_unexport(struct gpio_desc *desc)
 }
 EXPORT_SYMBOL_GPL(gpiod_unexport);
 
-int gpiochip_sysfs_register(struct gpio_device *gdev)
+int gpiochip_sysfs_register(struct gpio_chip *chip)
 {
+	struct gpio_device *gdev = chip->gpiodev;
 	struct gpiodev_data *data;
-	struct gpio_chip *chip;
 	struct device *parent;
 	int err;
 
@@ -994,12 +994,6 @@ int gpiochip_sysfs_register(struct gpio_device *gdev)
 	if (!class_is_registered(&gpio_class))
 		return 0;
 
-	guard(srcu)(&gdev->srcu);
-
-	chip = srcu_dereference(gdev->chip, &gdev->srcu);
-	if (!chip)
-		return -ENODEV;
-
 	/*
 	 * For sysfs backward compatibility we need to preserve this
 	 * preferred parenting to the gpio_chip parent field, if set.
@@ -1080,10 +1074,9 @@ void gpiochip_sysfs_unregister(struct gpio_chip *chip)
  */
 static int gpiofind_sysfs_register(struct gpio_chip *gc, const void *data)
 {
-	struct gpio_device *gdev = gc->gpiodev;
 	int ret;
 
-	ret = gpiochip_sysfs_register(gdev);
+	ret = gpiochip_sysfs_register(gc);
 	if (ret)
 		gpiochip_err(gc, "failed to register the sysfs entry: %d\n", ret);
 
diff --git a/drivers/gpio/gpiolib-sysfs.h b/drivers/gpio/gpiolib-sysfs.h
index 9ee2f9dd268f..aacc8e6454a4 100644
--- a/drivers/gpio/gpiolib-sysfs.h
+++ b/drivers/gpio/gpiolib-sysfs.h
@@ -7,12 +7,12 @@ struct gpio_device;
 
 #ifdef CONFIG_GPIO_SYSFS
 
-int gpiochip_sysfs_register(struct gpio_device *gdev);
+int gpiochip_sysfs_register(struct gpio_chip *chip);
 void gpiochip_sysfs_unregister(struct gpio_chip *chip);
 
 #else
 
-static inline int gpiochip_sysfs_register(struct gpio_device *gdev)
+static inline int gpiochip_sysfs_register(struct gpio_chip *chip)
 {
 	return 0;
 }
diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c
index 3ff57b1e51bf..74ee7bfb974c 100644
--- a/drivers/gpio/gpiolib.c
+++ b/drivers/gpio/gpiolib.c
@@ -882,14 +882,14 @@ static const struct device_type gpio_dev_type = {
 };
 
 #ifdef CONFIG_GPIO_CDEV
-#define gcdev_register(gdev, devt)	gpiolib_cdev_register((gdev), (devt))
+#define gcdev_register(gc, devt)	gpiolib_cdev_register((gc), (devt))
 #define gcdev_unregister(gdev)		gpiolib_cdev_unregister((gdev))
 #else
 /*
  * gpiolib_cdev_register() indirectly calls device_add(), which is still
  * required even when cdev is not selected.
  */
-#define gcdev_register(gdev, devt)	device_add(&(gdev)->dev)
+#define gcdev_register(gc, devt)	device_add(&(gc)->gpiodev->dev)
 #define gcdev_unregister(gdev)		device_del(&(gdev)->dev)
 #endif
 
@@ -897,8 +897,9 @@ static const struct device_type gpio_dev_type = {
  * An initial reference count has been held in gpiochip_add_data_with_key().
  * The caller should drop the reference via gpio_device_put() on errors.
  */
-static int gpiochip_setup_dev(struct gpio_device *gdev)
+static int gpiochip_setup_dev(struct gpio_chip *gc)
 {
+	struct gpio_device *gdev = gc->gpiodev;
 	struct fwnode_handle *fwnode = dev_fwnode(&gdev->dev);
 	int ret;
 
@@ -911,11 +912,11 @@ static int gpiochip_setup_dev(struct gpio_device *gdev)
 	if (fwnode && !fwnode->dev)
 		fwnode_dev_initialized(fwnode, false);
 
-	ret = gcdev_register(gdev, gpio_devt);
+	ret = gcdev_register(gc, gpio_devt);
 	if (ret)
 		return ret;
 
-	ret = gpiochip_sysfs_register(gdev);
+	ret = gpiochip_sysfs_register(gc);
 	if (ret)
 		goto err_remove_device;
 
@@ -962,13 +963,22 @@ static void machine_gpiochip_add(struct gpio_chip *gc)
 static void gpiochip_setup_devs(void)
 {
 	struct gpio_device *gdev;
+	struct gpio_chip *gc;
 	int ret;
 
 	guard(srcu)(&gpio_devices_srcu);
 
 	list_for_each_entry_srcu(gdev, &gpio_devices, list,
 				 srcu_read_lock_held(&gpio_devices_srcu)) {
-		ret = gpiochip_setup_dev(gdev);
+		guard(srcu)(&gdev->srcu);
+
+		gc = srcu_dereference(gdev->chip, &gdev->srcu);
+		if (!gc) {
+			dev_err(&gdev->dev, "Underlying GPIO chip is gone\n");
+			continue;
+		}
+
+		ret = gpiochip_setup_dev(gc);
 		if (ret) {
 			gpio_device_put(gdev);
 			dev_err(&gdev->dev,
@@ -1226,7 +1236,7 @@ int gpiochip_add_data_with_key(struct gpio_chip *gc, void *data,
 	 * (i.e., `gpio_bus_type` is ready).  Otherwise, defer until later.
 	 */
 	if (gpiolib_initialized) {
-		ret = gpiochip_setup_dev(gdev);
+		ret = gpiochip_setup_dev(gc);
 		if (ret)
 			goto err_teardown_shared;
 	}
-- 
2.53.0.310.g728cabbaf7-goog
Re: [PATCH v3 04/11] gpio: Ensure struct gpio_chip for gpiochip_setup_dev()
Posted by Bartosz Golaszewski 1 month, 1 week ago
On Fri, Feb 13, 2026 at 10:31 AM Tzung-Bi Shih <tzungbi@kernel.org> wrote:
>
> Ensure struct gpio_chip for gpiochip_setup_dev().  This eliminates a few
> checks for struct gpio_chip.
>
> Signed-off-by: Tzung-Bi Shih <tzungbi@kernel.org>
> ---
>
> -int gpiochip_sysfs_register(struct gpio_device *gdev)
> +int gpiochip_sysfs_register(struct gpio_chip *chip)
>  {
> +       struct gpio_device *gdev = chip->gpiodev;
>         struct gpiodev_data *data;
> -       struct gpio_chip *chip;
>         struct device *parent;
>         int err;
>
> @@ -994,12 +994,6 @@ int gpiochip_sysfs_register(struct gpio_device *gdev)
>         if (!class_is_registered(&gpio_class))
>                 return 0;
>
> -       guard(srcu)(&gdev->srcu);
> -
> -       chip = srcu_dereference(gdev->chip, &gdev->srcu);
> -       if (!chip)
> -               return -ENODEV;

I think it would make sense to add lockdep checks when removing guards
in non-static functions.

Bart