From mboxrd@z Thu Jan 1 00:00:00 1970 From: Mika Westerberg Subject: Re: [PATCH] ACPI / gpio: avoid warning for gpio hogging code Date: Tue, 8 Nov 2016 16:12:48 +0200 Message-ID: <20161108141248.GA1447@lahna.fi.intel.com> References: <20161108134035.1764500-1-arnd@arndb.de> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8bit Return-path: Content-Disposition: inline In-Reply-To: <20161108134035.1764500-1-arnd@arndb.de> Sender: linux-kernel-owner@vger.kernel.org To: Arnd Bergmann Cc: Linus Walleij , Alexandre Courbot , "Rafael J. Wysocki" , Dmitry Torokhov , Wei Yongjun , Christophe Ricard , linux-gpio@vger.kernel.org, linux-kernel@vger.kernel.org List-Id: linux-gpio@vger.kernel.org On Tue, Nov 08, 2016 at 02:40:06PM +0100, Arnd Bergmann wrote: > 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 Acked-by: Mika Westerberg