Commit ccfb6ff4 authored by Bartosz Golaszewski's avatar Bartosz Golaszewski
Browse files

gpio: don't set label from irq helpers 



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.

Don't actually set the label to "interrupt" in the above case but rather
use the newly added gpiod_get_label() helper to hide the logic that
atomically checks the descriptor flags and returns the address of a
static "interrupt" string.

Signed-off-by: default avatarBartosz Golaszewski <bartosz.golaszewski@linaro.org>
Reviewed-by: default avatarLinus Walleij <linus.walleij@linaro.org>
Acked-by: default avatarAndy Shevchenko <andriy.shevchenko@linux.intel.com>
parent d23dc4a9

drivers/gpio/gpiolib.c

+8 −13
Original line number Diff line number Diff line
@@ -107,7 +107,14 @@ static bool gpiolib_initialized; 


const char *gpiod_get_label(struct gpio_desc *desc)

{

	return desc->label;

	unsigned long flags;



	flags = READ_ONCE(desc->flags);

	if (test_bit(FLAG_USED_AS_IRQ, &flags) &&

	    !test_bit(FLAG_REQUESTED, &flags))

		return "interrupt";



	return test_bit(FLAG_REQUESTED, &flags) ? desc->label : NULL;

}



static inline void desc_set_label(struct gpio_desc *d, const char *label)
@@ -3599,14 +3606,6 @@ int gpiochip_lock_as_irq(struct gpio_chip *gc, unsigned int offset) 
	set_bit(FLAG_USED_AS_IRQ, &desc->flags);

	set_bit(FLAG_IRQ_IS_ENABLED, &desc->flags);



	/*

	 * If the consumer has not set up a label (such as when the

	 * IRQ is referenced from .to_irq()) we set up a label here

	 * so it is clear this is used as an interrupt.

	 */

	if (!desc->label)

		desc_set_label(desc, "interrupt");



	return 0;

}

EXPORT_SYMBOL_GPL(gpiochip_lock_as_irq);
@@ -3629,10 +3628,6 @@ void gpiochip_unlock_as_irq(struct gpio_chip *gc, unsigned int offset) 


	clear_bit(FLAG_USED_AS_IRQ, &desc->flags);

	clear_bit(FLAG_IRQ_IS_ENABLED, &desc->flags);



	/* If we only had this marking, erase it */

	if (desc->label && !strcmp(desc->label, "interrupt"))

		desc_set_label(desc, NULL);

}

EXPORT_SYMBOL_GPL(gpiochip_unlock_as_irq);