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=-11.2 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,URIBL_BLOCKED,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 00028C55178 for ; Mon, 2 Nov 2020 12:32:33 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id B51A42225B for ; Mon, 2 Nov 2020 12:32:33 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728847AbgKBMcc (ORCPT ); Mon, 2 Nov 2020 07:32:32 -0500 Received: from szxga04-in.huawei.com ([45.249.212.190]:6733 "EHLO szxga04-in.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728832AbgKBMca (ORCPT ); Mon, 2 Nov 2020 07:32:30 -0500 Received: from DGGEMS404-HUB.china.huawei.com (unknown [172.30.72.58]) by szxga04-in.huawei.com (SkyGuard) with ESMTP id 4CPskK2kPRzkdkY; Mon, 2 Nov 2020 20:32:25 +0800 (CST) Received: from [127.0.0.1] (10.57.60.129) by DGGEMS404-HUB.china.huawei.com (10.3.19.204) with Microsoft SMTP Server id 14.3.487.0; Mon, 2 Nov 2020 20:32:18 +0800 Subject: Re: [PATCH] drm/irq: Add irq as false detection To: Thomas Zimmermann , Tian Tao , , , , , , References: <1604315990-56787-1-git-send-email-tiantao6@hisilicon.com> <8a76d144-f8ba-bbbc-9177-53088f6dc73a@suse.de> From: "tiantao (H)" Message-ID: Date: Mon, 2 Nov 2020 20:32:17 +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: <8a76d144-f8ba-bbbc-9177-53088f6dc73a@suse.de> 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 20:09, Thomas Zimmermann 写道: > Hi > > Am 02.11.20 um 12:19 schrieb Tian Tao: >> Add the detection of false for irq, so that the EINVAL is not >> returned when dev->irq_enabled is false. >> >> Signed-off-by: Tian Tao >> --- >> drivers/gpu/drm/drm_irq.c | 3 +++ >> 1 file changed, 3 insertions(+) >> >> diff --git a/drivers/gpu/drm/drm_irq.c b/drivers/gpu/drm/drm_irq.c >> index 09d6e9e..7537a3d 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; >> + > > Dereferencing a pointer before NULL-checking it, is Yoda programming. :) > I'd just drop the test for !dev and assume that dev is always valid. > > I suggest to change the int return value to void and return nothing. > > Re-reading the actual implementation of this function, this location > might be too early. Further below there already is a test for > irq_enabled. Put a drm_WARN_ON around it and it should be fine. This way > the vblank handlers will be disabled and erroneous callers will see a > warning in the kernel's log. > thank you，I will send a new patch to fix that. > Best regards > Thomas > >> irq_enabled = dev->irq_enabled; >> dev->irq_enabled = false; >> >> >