From mboxrd@z Thu Jan 1 00:00:00 1970 From: Arnd Bergmann Subject: Re: [PATCH 1/4] gpiolib: introduce descriptor-based GPIO interface Date: Wed, 9 Jan 2013 10:35:22 +0000 Message-ID: <201301091035.23206.arnd@arndb.de> References: <1357629535-26033-1-git-send-email-acourbot@nvidia.com> <201301081259.29839.arnd@arndb.de> Mime-Version: 1.0 Content-Type: Text/Plain; charset="utf-8" Content-Transfer-Encoding: 7bit Return-path: Received: from moutng.kundenserver.de ([212.227.126.186]:59478 "EHLO moutng.kundenserver.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755272Ab3AIKfm (ORCPT ); Wed, 9 Jan 2013 05:35:42 -0500 In-Reply-To: Sender: linux-arch-owner@vger.kernel.org List-ID: To: Alexandre Courbot Cc: Grant Likely , Linus Walleij , Guenter Roeck , Linux Kernel Mailing List , linux-arch@vger.kernel.org, "linux-arm-kernel@lists.infradead.org" , "devicetree-discuss@lists.ozlabs.org" On Wednesday 09 January 2013, Alexandre Courbot wrote: > On Tue, Jan 8, 2013 at 9:59 PM, Arnd Bergmann wrote: > > Please avoid the use of IS_ERR_OR_NULL(), especially on interfaces you > > introduce yourself. AFAICT, gpiod_get cannot return NULL, so you > > should not check for that. > > Sure - you sound like IS_ERR_OR_NULL() is generally considered evil, Correct. > may I ask why this is the case? It's very hard to get right: either you are interested in the error code, and then you don't have one in some cases, or you don't care but have to check for it anyway. When you define a function, just make it clear what the expected return values are, either NULL for error or a negative ERR_PTR value, but not both. Arnd From mboxrd@z Thu Jan 1 00:00:00 1970 From: arnd@arndb.de (Arnd Bergmann) Date: Wed, 9 Jan 2013 10:35:22 +0000 Subject: [PATCH 1/4] gpiolib: introduce descriptor-based GPIO interface In-Reply-To: References: <1357629535-26033-1-git-send-email-acourbot@nvidia.com> <201301081259.29839.arnd@arndb.de> Message-ID: <201301091035.23206.arnd@arndb.de> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On Wednesday 09 January 2013, Alexandre Courbot wrote: > On Tue, Jan 8, 2013 at 9:59 PM, Arnd Bergmann wrote: > > Please avoid the use of IS_ERR_OR_NULL(), especially on interfaces you > > introduce yourself. AFAICT, gpiod_get cannot return NULL, so you > > should not check for that. > > Sure - you sound like IS_ERR_OR_NULL() is generally considered evil, Correct. > may I ask why this is the case? It's very hard to get right: either you are interested in the error code, and then you don't have one in some cases, or you don't care but have to check for it anyway. When you define a function, just make it clear what the expected return values are, either NULL for error or a negative ERR_PTR value, but not both. Arnd