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: c80f1ba75df2 ("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>

diff --git a/drivers/gpio/gpiolib-acpi.c b/drivers/gpio/gpiolib-acpi.c
index 83fcfff..fec93b9 100644 (file)
--- a/drivers/gpio/gpiolib-acpi.c
+++ b/drivers/gpio/gpiolib-acpi.c
@@ -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;