Commit c82064f2 authored Nov 08, 2016 by Arnd Bergmann Committed by Linus Walleij Nov 09, 2016

ACPI / gpio: avoid warning for gpio hogging code

The newly added acpi_gpiochip_scan_gpios function produces a few harmless
warnings:

drivers/gpio/gpiolib-acpi.c: In function ‘acpi_gpiochip_add’:
drivers/gpio/gpiolib-acpi.c:925:7: error: ‘dflags’ may be used uninitialized in this function [-Werror=maybe-uninitialized]
drivers/gpio/gpiolib-acpi.c:925:9: error: ‘lflags’ may be used uninitialized in this function [-Werror=maybe-uninitialized]

The problem is that he compiler cannot know that a negative return value
from fwnode_property_read_u32_array() or acpi_gpiochip_pin_to_gpio_offset()
implies that the IS_ERR(gpio_desc) is true, as the value could in theory
be below -MAX_ERRNO.

The function already initializes its output values to zero, and moving
that intialization a little higher up ensures that we can never have
uninitialized data in the caller.

Fixes: c80f1ba7 ("ACPI / gpio: Add hogging support")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

parent e0275034

drivers/gpio/gpiolib-acpi.c

+4 −4

Original line number	Diff line number	Diff line
		@@ -866,6 +866,10 @@ static struct gpio_desc *acpi_gpiochip_parse_own_gpio(
		u32 gpios[2];
		int ret;

		*lflags = 0;
		*dflags = 0;
		*name = NULL;

		ret = fwnode_property_read_u32_array(fwnode, "gpios", gpios,
		ARRAY_SIZE(gpios));
		if (ret < 0)
		@@ -879,10 +883,6 @@ static struct gpio_desc *acpi_gpiochip_parse_own_gpio(
		if (IS_ERR(desc))
		return desc;

		*lflags = 0;
		*dflags = 0;
		*name = NULL;

		if (gpios[1])
		*lflags \|= GPIO_ACTIVE_LOW;