From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <linux-kernel-owner@vger.kernel.org>
Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand
        id S1752511AbcKHOM6 (ORCPT <rfc822;w@1wt.eu>);
        Tue, 8 Nov 2016 09:12:58 -0500
Received: from mga02.intel.com ([134.134.136.20]:35808 "EHLO mga02.intel.com"
        rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP
        id S1751455AbcKHOM5 (ORCPT <rfc822;linux-kernel@vger.kernel.org>);
        Tue, 8 Nov 2016 09:12:57 -0500
X-ExtLoop1: 1
X-IronPort-AV: E=Sophos;i="5.31,462,1473145200"; 
   d="scan'208";a="1201781"
Date: Tue, 8 Nov 2016 16:12:48 +0200
From: Mika Westerberg <mika.westerberg@linux.intel.com>
To: Arnd Bergmann <arnd@arndb.de>
Cc: Linus Walleij <linus.walleij@linaro.org>,
        Alexandre Courbot <gnurou@gmail.com>,
        "Rafael J. Wysocki" <rafael.j.wysocki@intel.com>,
        Dmitry Torokhov <dmitry.torokhov@gmail.com>,
        Wei Yongjun <weiyongjun1@huawei.com>,
        Christophe Ricard <christophe.ricard@gmail.com>,
        linux-gpio@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] ACPI / gpio: avoid warning for gpio hogging code
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-Disposition: inline
Content-Transfer-Encoding: 8bit
In-Reply-To: <20161108134035.1764500-1-arnd@arndb.de>
Organization: Intel Finland Oy - BIC 0357606-4 - Westendinkatu 7, 02160 Espoo
User-Agent: Mutt/1.7.1 (2016-10-04)
Sender: linux-kernel-owner@vger.kernel.org
List-ID: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@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 <arnd@arndb.de>

Acked-by: Mika Westerberg <mika.westerberg@linux.intel.com>