[PATCH v3 23/24] gpio: remove the RW semaphore from the GPIO device

Bartosz Golaszewski
2024-02-08T09:59:51Z

With all accesses to gdev->chip being protected with SRCU, we can now
remove the RW-semaphore specific to the character device which
fullfilled the same role up to this point.

Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
---
drivers/gpio/gpiolib-cdev.c | 1 -
drivers/gpio/gpiolib.c | 4 ----
drivers/gpio/gpiolib.h | 5 -----
3 files changed, 10 deletions(-)

diff --git a/drivers/gpio/gpiolib-cdev.c b/drivers/gpio/gpiolib-cdev.c
index ccdeed013f6b..9323b357df43 100644
--- a/drivers/gpio/gpiolib-cdev.c
+++ b/drivers/gpio/gpiolib-cdev.c
@@ -24,7 +24,6 @@
#include <linux/pinctrl/consumer.h>
#include <linux/poll.h>
#include <linux/rbtree.h>
-#include <linux/rwsem.h>
#include <linux/seq_file.h>
#include <linux/spinlock.h>
#include <linux/timekeeping.h>
diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c
index a14717a3e222..97829f0c8487 100644
--- a/drivers/gpio/gpiolib.c
+++ b/drivers/gpio/gpiolib.c
@@ -963,7 +963,6 @@ int gpiochip_add_data_with_key(struct gpio_chip *gc, void *data,

BLOCKING_INIT_NOTIFIER_HEAD(&gdev->line_state_notifier);
BLOCKING_INIT_NOTIFIER_HEAD(&gdev->device_notifier);
- init_rwsem(&gdev->sem);

ret = init_srcu_struct(&gdev->srcu);
if (ret)
@@ -1102,8 +1101,6 @@ void gpiochip_remove(struct gpio_chip *gc)
struct gpio_device *gdev = gc->gpiodev;
unsigned int i;

- down_write(&gdev->sem);
-
/* FIXME: should the legacy sysfs handling be moved to gpio_device? */
gpiochip_sysfs_unregister(gdev);
gpiochip_free_hogs(gc);
@@ -1142,7 +1139,6 @@ void gpiochip_remove(struct gpio_chip *gc)
* gone.
*/
gcdev_unregister(gdev);
- up_write(&gdev->sem);
gpio_device_put(gdev);
}
EXPORT_SYMBOL_GPL(gpiochip_remove);
diff --git a/drivers/gpio/gpiolib.h b/drivers/gpio/gpiolib.h
index b3810f7d286a..07443d26cbca 100644
--- a/drivers/gpio/gpiolib.h
+++ b/drivers/gpio/gpiolib.h
@@ -16,7 +16,6 @@
#include <linux/gpio/driver.h>
#include <linux/module.h>
#include <linux/notifier.h>
-#include <linux/rwsem.h>
#include <linux/srcu.h>

#define GPIOCHIP_NAME "gpiochip"
@@ -46,9 +45,6 @@
* requested, released or reconfigured
* @device_notifier: used to notify character device wait queues about the GPIO
* device being unregistered
- * @sem: protects the structure from a NULL-pointer dereference of @chip by
- * user-space operations when the device gets unregistered during
- * a hot-unplug event
* @srcu: protects the pointer to the underlying GPIO chip
* @pin_ranges: range of pins served by the GPIO driver
*
@@ -73,7 +69,6 @@ struct gpio_device {
struct list_head list;
struct blocking_notifier_head line_state_notifier;
struct blocking_notifier_head device_notifier;
- struct rw_semaphore sem;
struct srcu_struct srcu;

#ifdef CONFIG_PINCTRL
--
2.40.1