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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 8593AC4332F for ; Fri, 10 Dec 2021 16:38:47 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S243756AbhLJQmV (ORCPT ); Fri, 10 Dec 2021 11:42:21 -0500 Received: from mxout02.lancloud.ru ([45.84.86.82]:37856 "EHLO mxout02.lancloud.ru" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S239270AbhLJQmU (ORCPT ); Fri, 10 Dec 2021 11:42:20 -0500 Received: from LanCloud DKIM-Filter: OpenDKIM Filter v2.11.0 mxout02.lancloud.ru 43106235E65B Received: from LanCloud Received: from LanCloud Received: from LanCloud Subject: Re: [PATCH v1 1/2] ata: libahci_platform: Get rid of dup message when IRQ can't be retrieved To: Andy Shevchenko , Damien Le Moal CC: Andy Shevchenko , , Linux Kernel Mailing List , Hans de Goede , "Jens Axboe" References: <20211209145937.77719-1-andriy.shevchenko@linux.intel.com> From: Sergey Shtylyov Organization: Open Mobile Platform Message-ID: <587c35bd-8877-030e-6236-d0d8c2b6811c@omp.ru> Date: Fri, 10 Dec 2021 19:38:40 +0300 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.10.1 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset="utf-8" Content-Language: en-US Content-Transfer-Encoding: 7bit X-Originating-IP: [192.168.11.198] X-ClientProxiedBy: LFEXT02.lancloud.ru (fd00:f066::142) To LFEX1907.lancloud.ru (fd00:f066::207) Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 12/10/21 11:47 AM, Andy Shevchenko wrote: >>> platform_get_irq() will print a message when it fails. >>> No need to repeat this. >>> >>> While at it, drop redundant check for 0 as platform_get_irq() spills >>> out a big WARN() in such case. >> >> The reason you should be able to remove the "if (!irq)" test is that >> platform_get_irq() never returns 0. At least, that is what the function kdoc >> says. But looking at platform_get_irq_optional(), which is called by >> platform_get_irq(), the out label is: >> >> WARN(ret == 0, "0 is an invalid IRQ number\n"); >> return ret; >> >> So 0 will be returned as-is. That is rather weird. That should be fixed to >> return -ENXIO: >> >> if (WARN(ret == 0, "0 is an invalid IRQ number\n")) >> return -ENXIO; -ENXIO seems to me more fitting indeed (than -EINVAL that I used). > > No, this is wrong for the same reasons I explained to Sergey. I fail to understand you, sorry. We're going in circles, it seems... :-/ > The problem is that this is _optional API and it has been misdesigned. > Replacing things like above will increase the mess. What's wrong with replacing IRQ0 with -ENXIO now? platform_get_irq_optional() (as in your patch) could then happily return 0 ISO -ENXIO. Contrarywise, if we don't replace IRQ0 with -ENXIO, platform_get_irq_optional() will return 0 for both IRQ0 and missing IRQ! Am I clear enough? If you don't understand me now, I don't know what to say... :-/ > >> return ret; >> >> Otherwise, I do not think that removing the "if (!irq)" hunk is safe. no ? > > No. This is not a business of the caller to workaround implementation > details (bugs) of the core APIs. > If something goes wrong, then it's platform_get_irq() to blame, and > not the libahci_platform. I'm repeating myself already: we don't work around the bug in platform_get_irq(), we're working around the driver subsystems that treat 0 specially (and so don't support IRQ0); libata treats 0 as an indication of the polling mode (moreover, it will curse if you pass to it both IRQ == 0 and a pointer to an interrupt handler! Am I clear enough this time? :-) MBR, Sergey