gpio: provide and use gpiod_get_label()

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>
Acked-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>

diff --git a/drivers/gpio/gpiolib-cdev.c b/drivers/gpio/gpiolib-cdev.c
index 34d6712fa07cff0a0a0407310b18642cd0aeeeed..2c0a0700762d8d94e3be0ac43ad232f97a1392c8 100644 (file)
--- 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 03d7c3f92f5e3d53ed9ff0566f62d9e408a154b0..c014404c3bed4f0bf087e85eac8ee06f9723ad8b 100644 (file)
--- 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 c3ae5bfa3f2e48ccc01f757a95bc4cf9810505f0..1058f326fe2b76df30831a0eadaf1e85204bac91 100644 (file)
--- 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