[PATCH v3 06/24] gpio: add SRCU infrastructure to struct gpio_desc

Bartosz Golaszewski
2024-02-08T09:59:33Z

Extend the GPIO descriptor with an SRCU structure in order to serialize
the access to the label. Initialize and clean it up where applicable.

Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
---
drivers/gpio/gpiolib.c | 18 ++++++++++++++++--
drivers/gpio/gpiolib.h | 3 +++
2 files changed, 19 insertions(+), 2 deletions(-)

diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c
index fbfddc9860fd..b26d39bc3389 100644
--- a/drivers/gpio/gpiolib.c
+++ b/drivers/gpio/gpiolib.c
@@ -672,6 +672,10 @@ EXPORT_SYMBOL_GPL(gpiochip_line_is_valid);
static void gpiodev_release(struct device *dev)
{
struct gpio_device *gdev = to_gpio_device(dev);
+ unsigned int i;
+
+ for (i = 0; i < gdev->ngpio; i++)
+ cleanup_srcu_struct(&gdev->descs[i].srcu);

ida_free(&gpio_ida, gdev->id);
kfree_const(gdev->label);
@@ -836,7 +840,7 @@ int gpiochip_add_data_with_key(struct gpio_chip *gc, void *data,
struct lock_class_key *request_key)
{
struct gpio_device *gdev;
- unsigned int i;
+ unsigned int i, j;
int base = 0;
int ret = 0;

@@ -970,6 +974,13 @@ int gpiochip_add_data_with_key(struct gpio_chip *gc, void *data,
for (i = 0; i < gc->ngpio; i++) {
struct gpio_desc *desc = &gdev->descs[i];

+ ret = init_srcu_struct(&desc->srcu);
+ if (ret) {
+ for (j = 0; j < i; j++)
+ cleanup_srcu_struct(&gdev->descs[j].srcu);
+ goto err_remove_of_chip;
+ }
+
if (gc->get_direction && gpiochip_line_is_valid(gc, i)) {
assign_bit(FLAG_IS_OUT,
&desc->flags, !gc->get_direction(gc, i));
@@ -981,7 +992,7 @@ int gpiochip_add_data_with_key(struct gpio_chip *gc, void *data,

ret = gpiochip_add_pin_ranges(gc);
if (ret)
- goto err_remove_of_chip;
+ goto err_cleanup_desc_srcu;

acpi_gpiochip_add(gc);

@@ -1020,6 +1031,9 @@ int gpiochip_add_data_with_key(struct gpio_chip *gc, void *data,
gpiochip_irqchip_free_valid_mask(gc);
err_remove_acpi_chip:
acpi_gpiochip_remove(gc);
+err_cleanup_desc_srcu:
+ for (i = 0; i < gdev->ngpio; i++)
+ cleanup_srcu_struct(&gdev->descs[i].srcu);
err_remove_of_chip:
gpiochip_free_hogs(gc);
of_gpiochip_remove(gc);
diff --git a/drivers/gpio/gpiolib.h b/drivers/gpio/gpiolib.h
index 1058f326fe2b..6e14b629c48b 100644
--- a/drivers/gpio/gpiolib.h
+++ b/drivers/gpio/gpiolib.h
@@ -17,6 +17,7 @@
#include <linux/module.h>
#include <linux/notifier.h>
#include <linux/rwsem.h>
+#include <linux/srcu.h>

#define GPIOCHIP_NAME "gpiochip"

@@ -147,6 +148,7 @@ void gpiod_line_state_notify(struct gpio_desc *desc, unsigned long action);
* @label: Name of the consumer
* @name: Line name
* @hog: Pointer to the device node that hogs this line (if any)
+ * @srcu: SRCU struct protecting the label pointer.
*
* These are obtained using gpiod_get() and are preferable to the old
* integer-based handles.
@@ -184,6 +186,7 @@ struct gpio_desc {
#ifdef CONFIG_OF_DYNAMIC
struct device_node *hog;
#endif
+ struct srcu_struct srcu;
};

#define gpiod_not_found(desc) (IS_ERR(desc) && PTR_ERR(desc) == -ENOENT)
--
2.40.1