From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-0.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 56DB6C4332D for ; Thu, 19 Mar 2020 08:48:57 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 2DE5A20732 for ; Thu, 19 Mar 2020 08:48:57 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727095AbgCSIsB (ORCPT ); Thu, 19 Mar 2020 04:48:01 -0400 Received: from Galois.linutronix.de ([193.142.43.55]:59784 "EHLO Galois.linutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727053AbgCSIsB (ORCPT ); Thu, 19 Mar 2020 04:48:01 -0400 Received: from p5de0bf0b.dip0.t-ipconnect.de ([93.224.191.11] helo=nanos.tec.linutronix.de) by Galois.linutronix.de with esmtpsa (TLS1.2:DHE_RSA_AES_256_CBC_SHA256:256) (Exim 4.80) (envelope-from ) id 1jEqqD-0002xp-G4; Thu, 19 Mar 2020 09:47:49 +0100 Received: by nanos.tec.linutronix.de (Postfix, from userid 1000) id AB625103088; Thu, 19 Mar 2020 09:47:47 +0100 (CET) From: Thomas Gleixner To: Bjorn Helgaas Cc: Marc Gonzalez , Aman Sharma , Lorenzo Pieralisi , Thomas Petazzoni , Andrew Murray , Linus Walleij , Ryder Lee , Karthikeyan Mitran , Hou Zhiqiang , Mans Rullgard , Matthias Brugger , linux-pci@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, linux-mediatek@lists.infradead.org, Marc Zyngier Subject: Re: [PATCH 4/5] pci: handled return value of platform_get_irq correctly In-Reply-To: <20200318222238.GA247500@google.com> References: <20200318222238.GA247500@google.com> Date: Thu, 19 Mar 2020 09:47:47 +0100 Message-ID: <877dzgennw.fsf@nanos.tec.linutronix.de> MIME-Version: 1.0 Content-Type: text/plain X-Linutronix-Spam-Score: -1.0 X-Linutronix-Spam-Level: - X-Linutronix-Spam-Status: No , -1.0 points, 5.0 required, ALL_TRUSTED=-1,SHORTCIRCUIT=-0.0001 Sender: linux-pci-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-pci@vger.kernel.org Bjorn Helgaas writes: > On Wed, Mar 18, 2020 at 02:42:48PM +0100, Thomas Gleixner wrote: >> Bjorn Helgaas writes: >> > On Fri, Mar 13, 2020 at 04:56:42PM -0500, Bjorn Helgaas wrote: >> >> On Fri, Mar 13, 2020 at 10:05:58PM +0100, Thomas Gleixner wrote: >> >> > > I think the best pattern is: >> >> > > >> >> > > irq = platform_get_irq(pdev, i); >> >> > > if (irq < 0) >> >> > > return irq; >> >> > >> >> > Careful. 0 is not a valid interrupt. >> >> >> >> Should callers of platform_get_irq() check for a 0 return value? >> >> About 900 of them do not. >> >> I don't know what I was looking at. >> >> platform_get_irq() does the right thing already, so checking for irq < 0 >> is sufficient. >> >> Sorry for the confusion! > > Thanks, I was indeed confused! Maybe we could reduce future confusion > by strengthening the comments slightly, e.g., > > - * Return: IRQ number on success, negative error number on failure. > + * Return: non-zero IRQ number on success, negative error number on failure. > > I don't want to push my luck, but it's pretty hard to prove that > platform_get_irq() never returns 0. What would you think of something > like the following? No objections from my side.