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=-11.3 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,NICE_REPLY_A, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=ham 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 6F14EC00A89 for ; Mon, 2 Nov 2020 09:08:35 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 10EBF223AB for ; Mon, 2 Nov 2020 09:08:35 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728344AbgKBJId (ORCPT ); Mon, 2 Nov 2020 04:08:33 -0500 Received: from szxga04-in.huawei.com ([45.249.212.190]:6729 "EHLO szxga04-in.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727806AbgKBJIc (ORCPT ); Mon, 2 Nov 2020 04:08:32 -0500 Received: from DGGEMS405-HUB.china.huawei.com (unknown [172.30.72.58]) by szxga04-in.huawei.com (SkyGuard) with ESMTP id 4CPn936cbxzkdXL; Mon, 2 Nov 2020 17:06:47 +0800 (CST) Received: from [127.0.0.1] (10.57.60.129) by DGGEMS405-HUB.china.huawei.com (10.3.19.205) with Microsoft SMTP Server id 14.3.487.0; Mon, 2 Nov 2020 17:06:43 +0800 Subject: Re: [PATCH] drm/hisilicon: Remove redundant null check To: Thomas Zimmermann , Tian Tao , , , , , , , , References: <1604050046-64539-1-git-send-email-tiantao6@hisilicon.com> <2dbbbad0-53cf-52cc-3b6b-0d1547f7e085@suse.de> From: "tiantao (H)" Message-ID: <48f68940-14a4-6ea7-4296-53970cd74015@huawei.com> Date: Mon, 2 Nov 2020 17:06:43 +0800 User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:60.0) Gecko/20100101 Thunderbird/60.8.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset="utf-8"; format=flowed Content-Transfer-Encoding: 8bit X-Originating-IP: [10.57.60.129] X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 在 2020/11/2 17:03, Thomas Zimmermann 写道: > Hi > > Am 02.11.20 um 09:46 schrieb tiantao (H): >> >> >> 在 2020/11/2 16:32, Thomas Zimmermann 写道: >>> Hi >>> >>> Am 30.10.20 um 10:27 schrieb Tian Tao: >>>> drm_irq_uninstall can handle the case where dev->irq_enable is false, >>>> so Remove redundant null check. >>>> >>>> Signed-off-by: Tian Tao >>>> --- >>>>   drivers/gpu/drm/hisilicon/hibmc/hibmc_drm_drv.c | 6 +++--- >>>>   1 file changed, 3 insertions(+), 3 deletions(-) >>>> >>>> diff --git a/drivers/gpu/drm/hisilicon/hibmc/hibmc_drm_drv.c >>>> b/drivers/gpu/drm/hisilicon/hibmc/hibmc_drm_drv.c >>>> index 0c1b40d..b71589b1 100644 >>>> --- a/drivers/gpu/drm/hisilicon/hibmc/hibmc_drm_drv.c >>>> +++ b/drivers/gpu/drm/hisilicon/hibmc/hibmc_drm_drv.c >>>> @@ -246,13 +246,13 @@ static int hibmc_unload(struct drm_device *dev) >>>>         drm_atomic_helper_shutdown(dev); >>>>   -    if (dev->irq_enabled) >>>> -        drm_irq_uninstall(dev); >>>> - >>>> +    drm_irq_uninstall(dev); >>> >>> Removing this check would at least result in an error, [1] so rather >>> leave it in for now. >>> >> Now there seems to be no driver to check the return value of >> drm_irq_uninstall > > True. No clean-up code should ever fail. But currently, it's not handled > by drm_irq_uninstall(). > > A better fix would be to have drm_irq_uninstall() return early with a > warning if IRQs are disabled. And for most drivers, a managed version of > drm_irq_install() would be useful. > Codes like the following diff --git a/drivers/gpu/drm/drm_irq.c b/drivers/gpu/drm/drm_irq.c index 09d6e9e..572357c 100644 --- a/drivers/gpu/drm/drm_irq.c +++ b/drivers/gpu/drm/drm_irq.c @@ -172,6 +172,9 @@ int drm_irq_uninstall(struct drm_device *dev) bool irq_enabled; int i; + if(!dev->irq_enabled || !dev) + return 0; > Best regards > Thomas > >>> Instead, we could discuss if drm_irq_install() should become a managed >>> interface. >> >> Codes like the following >> diff --git a/drivers/gpu/drm/drm_irq.c b/drivers/gpu/drm/drm_irq.c >> index 09d6e9e..572357c 100644 >> --- a/drivers/gpu/drm/drm_irq.c >> +++ b/drivers/gpu/drm/drm_irq.c >> @@ -172,6 +172,9 @@ int drm_irq_uninstall(struct drm_device *dev) >>         bool irq_enabled; >>         int i; >> >> +       if(!dev->irq_enabled || !dev) >> +               return 0; >> >>> >>> Best regards >>> Thomas >>> >>> [1] >>> https://elixir.bootlin.com/linux/latest/source/drivers/gpu/drm/drm_irq.c#L201 >>> >>> >>>>       pci_disable_msi(dev->pdev); >>>> + >>>>       hibmc_kms_fini(priv); >>>>       hibmc_mm_fini(priv); >>>>       dev->dev_private = NULL; >>>> + >>>>       return 0; >>>>   } >>>> >>> >> >