[PATCH v3 04/24] gpio: provide and use gpiod_get_label()

Bartosz Golaszewski
2024-02-08T09:59:31Z

We will soon serialize access to the descriptor label using SRCU. The
write-side of the protection will require calling synchronize_srcu()
which must not be called from atomic context. We have two irq helpers:
gpiochip_lock_as_irq() and gpiochip_unlock_as_irq() that set the label
if the GPIO is not requested but is being used as interrupt. They are
called with a spinlock held from the interrupt subsystem.

They must not do it if we are to use SRCU so instead let's move the
special corner case to a dedicated getter.

First: let's implement and use the getter where it's applicable.

Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
---
drivers/gpio/gpiolib-cdev.c | 4 ++--
drivers/gpio/gpiolib.c | 9 +++++++--
drivers/gpio/gpiolib.h | 1 +
3 files changed, 10 insertions(+), 4 deletions(-)

diff --git a/drivers/gpio/gpiolib-cdev.c b/drivers/gpio/gpiolib-cdev.c
index 34d6712fa07c..2c0a0700762d 100644
--- a/drivers/gpio/gpiolib-cdev.c
+++ b/drivers/gpio/gpiolib-cdev.c
@@ -2305,8 +2305,8 @@ static void gpio_desc_to_lineinfo(struct gpio_desc *desc,
if (desc->name)
strscpy(info->name, desc->name, sizeof(info->name));

- if (desc->label)
- strscpy(info->consumer, desc->label,
+ if (gpiod_get_label(desc))
+ strscpy(info->consumer, gpiod_get_label(desc),
sizeof(info->consumer));

dflags = READ_ONCE(desc->flags);
diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c
index 8ca9aebfa81f..8331fdbb6faa 100644
--- a/drivers/gpio/gpiolib.c
+++ b/drivers/gpio/gpiolib.c
@@ -105,6 +105,11 @@ static void gpiochip_irqchip_free_valid_mask(struct gpio_chip *gc);

static bool gpiolib_initialized;

+const char *gpiod_get_label(struct gpio_desc *desc)
+{
+ return desc->label;
+}
+
static inline void desc_set_label(struct gpio_desc *d, const char *label)
{
d->label = label;
@@ -2391,7 +2396,7 @@ char *gpiochip_dup_line_label(struct gpio_chip *gc, unsigned int offset)
*
* Until this happens, this allocation needs to be atomic.
*/
- label = kstrdup(desc->label, GFP_ATOMIC);
+ label = kstrdup(gpiod_get_label(desc), GFP_ATOMIC);
if (!label)
return ERR_PTR(-ENOMEM);

@@ -4732,7 +4737,7 @@ static void gpiolib_dbg_show(struct seq_file *s, struct gpio_device *gdev)
is_irq = test_bit(FLAG_USED_AS_IRQ, &desc->flags);
active_low = test_bit(FLAG_ACTIVE_LOW, &desc->flags);
seq_printf(s, " gpio-%-3d (%-20.20s|%-20.20s) %s %s %s%s\n",
- gpio, desc->name ?: "", desc->label,
+ gpio, desc->name ?: "", gpiod_get_label(desc),
is_out ? "out" : "in ",
value >= 0 ? (value ? "hi" : "lo") : "? ",
is_irq ? "IRQ " : "",
diff --git a/drivers/gpio/gpiolib.h b/drivers/gpio/gpiolib.h
index c3ae5bfa3f2e..1058f326fe2b 100644
--- a/drivers/gpio/gpiolib.h
+++ b/drivers/gpio/gpiolib.h
@@ -208,6 +208,7 @@ int gpio_set_debounce_timeout(struct gpio_desc *desc, unsigned int debounce);
int gpiod_hog(struct gpio_desc *desc, const char *name,
unsigned long lflags, enum gpiod_flags dflags);
int gpiochip_get_ngpios(struct gpio_chip *gc, struct device *dev);
+const char *gpiod_get_label(struct gpio_desc *desc);

/*
* Return the GPIO number of the passed descriptor relative to its chip
--
2.40.1