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 mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 0E7DDC433F5 for ; Wed, 6 Oct 2021 06:32:45 +0000 (UTC) Received: from gabe.freedesktop.org (gabe.freedesktop.org [131.252.210.177]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id C658F61186 for ; Wed, 6 Oct 2021 06:32:44 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.1 mail.kernel.org C658F61186 Authentication-Results: mail.kernel.org; dmarc=fail (p=quarantine dis=none) header.from=amd.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=lists.freedesktop.org Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id F3D016F61D; Wed, 6 Oct 2021 06:32:42 +0000 (UTC) Received: from NAM12-DM6-obe.outbound.protection.outlook.com (mail-dm6nam12on2056.outbound.protection.outlook.com [40.107.243.56]) by gabe.freedesktop.org (Postfix) with ESMTPS id 282596F61A; Wed, 6 Oct 2021 06:32:41 +0000 (UTC) ARC-Seal: i=1; a=rsa-sha256; s=arcselector9901; d=microsoft.com; cv=none; b=gXjaoSLgW1TwWQSm19LEsIoIkzvOtMhaGd0duDe09izs2PCBTV2yzdlIOBlI8S1Xldrm9wI1/2NOTA1Yi3mRRyCNllxxyZjo+4menl2toOLfmJ8GpML60kuZguKhy5r37l0eP5YhB3iUOmawjGagvMHnLxr+vZtWjyRFLfcVCh8XL3ZPPIjg9Wxogxe9T9cPwB43NvofsIy32jtQQEJdoSjcd27hjIDW0EKUAn62lSEUf96fLLsf0idK+7kfP55wSsmZop3GiV2rszZJvCqPMT3tOZx2gxCVX7Rqa4DQcUTWur9H26BsN34XLPbGIUojOFAQCf5pNSxUlITeAdiqog== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=microsoft.com; s=arcselector9901; h=From:Date:Subject:Message-ID:Content-Type:MIME-Version:X-MS-Exchange-AntiSpam-MessageData-ChunkCount:X-MS-Exchange-AntiSpam-MessageData-0:X-MS-Exchange-AntiSpam-MessageData-1; bh=DOvWuEoIjiZA7EMSLzinl+4Qf5PkhADkSkgnmO9eP/g=; b=k52Z08nmMHuGPbEvjwZikAVPA5A9pHC/9EkkW1wSkdqDKO3VoAjq83FgkO7zajfhbDXoAT13uqrXmU/G4yRe9VF/bqGop/9NtIp8RDgQYOOoHRUAgFBGdIJ85wa4FNmlY2bPqvS3fkAAEKV/JF0D6luB4nq+hh0OwOm9RmzI2Y/1DoDLeym5WM7dDLPB49pLnQxXUA68IZem9gKCvTz7N4dzHiooTstYq/6y7M3BnJg/2QKFkakbvqm3SEG35vH/SnNiOWgznOfV407H1ist9Dj/3nwLonmThBgg+L5qnT0kPCyBdEnb9u14ayMAw/jKpsGuGJufS2s24JPvxETP1w== ARC-Authentication-Results: i=1; mx.microsoft.com 1; spf=pass smtp.mailfrom=amd.com; dmarc=pass action=none header.from=amd.com; dkim=pass header.d=amd.com; arc=none DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=amd.com; s=selector1; h=From:Date:Subject:Message-ID:Content-Type:MIME-Version:X-MS-Exchange-SenderADCheck; bh=DOvWuEoIjiZA7EMSLzinl+4Qf5PkhADkSkgnmO9eP/g=; b=DYdAfQFYTVqT5KCgALplsnP3r2GX7XOXU4C4YmfPbKCmMBlFk+5Y6a+ryXk1UXN2XSgWJi+9bFJi0nB/gpu3+6qQGSH5LWEHaZqw3JnnGSd3Kj0yCVyP/Nejdl9jGx7YN6oeI49ThnJcw/jS8iTl+j6DXqUI0LZznO9u7XugkLU= Authentication-Results: amd.com; dkim=none (message not signed) header.d=none;amd.com; dmarc=none action=none header.from=amd.com; Received: from DM6PR12MB3930.namprd12.prod.outlook.com (2603:10b6:5:1c9::19) by DM6PR12MB4356.namprd12.prod.outlook.com (2603:10b6:5:2aa::8) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.4566.17; Wed, 6 Oct 2021 06:32:39 +0000 Received: from DM6PR12MB3930.namprd12.prod.outlook.com ([fe80::591a:8986:aca2:c560]) by DM6PR12MB3930.namprd12.prod.outlook.com ([fe80::591a:8986:aca2:c560%3]) with mapi id 15.20.4566.023; Wed, 6 Oct 2021 06:32:39 +0000 Subject: Re: [PATCH 1/1] drm/amdgpu: ignore -EPERM error from debugfs To: =?UTF-8?Q?Christian_K=c3=b6nig?= , "Das, Nirmoy" , amd-gfx@lists.freedesktop.org, dri-devel , Daniel Vetter Cc: shashank.sharma@amd.com References: <20211005131115.25595-1-nirmoy.das@amd.com> <182c1454-102e-cf2f-80eb-09baa57f8e82@amd.com> <45342056-8e15-bdb0-0237-d11476bcc8fa@amd.com> <36880798-83c8-5566-dfe8-a18b9c4783f6@amd.com> From: "Lazar, Lijo" Message-ID: <84a62bf8-65e3-0b3b-91ef-bef5f4060601@amd.com> Date: Wed, 6 Oct 2021 12:02:24 +0530 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:78.0) Gecko/20100101 Thunderbird/78.14.0 In-Reply-To: <36880798-83c8-5566-dfe8-a18b9c4783f6@amd.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 8bit X-ClientProxiedBy: PN1PR0101CA0068.INDPRD01.PROD.OUTLOOK.COM (2603:1096:c00:d::30) To DM6PR12MB3930.namprd12.prod.outlook.com (2603:10b6:5:1c9::19) MIME-Version: 1.0 Received: from [10.252.81.250] (165.204.159.242) by PN1PR0101CA0068.INDPRD01.PROD.OUTLOOK.COM (2603:1096:c00:d::30) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.4566.14 via Frontend Transport; Wed, 6 Oct 2021 06:32:35 +0000 X-MS-PublicTrafficType: Email X-MS-Office365-Filtering-Correlation-Id: bbe2bcf0-b041-4f3b-9c9a-08d9889317d0 X-MS-TrafficTypeDiagnostic: DM6PR12MB4356: X-MS-Exchange-Transport-Forked: True X-Microsoft-Antispam-PRVS: X-MS-Oob-TLC-OOBClassifiers: OLM:454; X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0; X-Microsoft-Antispam-Message-Info: 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 X-Forefront-Antispam-Report: CIP:255.255.255.255; CTRY:; LANG:en; SCL:1; SRV:; IPV:NLI; SFV:NSPM; H:DM6PR12MB3930.namprd12.prod.outlook.com; PTR:; CAT:NONE; SFS:(4636009)(366004)(26005)(6486002)(31686004)(83380400001)(86362001)(508600001)(316002)(66476007)(66946007)(66556008)(66574015)(186003)(2616005)(16576012)(4326008)(956004)(31696002)(110136005)(38100700002)(36756003)(2906002)(8676002)(53546011)(6666004)(5660300002)(8936002)(45980500001)(43740500002); DIR:OUT; SFP:1101; X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: =?utf-8?B?ckcxUG01T0s5Y1Y2ZlpKYmlSTy9HNUt1RnFWUEROQjkxb0J6Y3pjaC9NYkhw?= =?utf-8?B?RzlZZGIvUVl2QjlmNXFYck45SlE1bUNSSVordE1qZE85WG5ZQmRhUEt4Y3da?= =?utf-8?B?RXNhWk1HR0RibmhjYWdTR0tTcHpJKytSUXFrK1B1amd2TDJ2d1BvaXFDK0ta?= =?utf-8?B?bXM0MGtPS0s1c1R1YlRqMGYvSUZhT3ZRcHp5cmNhRzlYVVY0NDgyUDZoZytk?= =?utf-8?B?WEI1WEllNWFzRFpYRzBPTWNOQUtHMkNMTTl2ODhiWC9JT0JNZUtsWGZNcWJo?= =?utf-8?B?TFJld1ExM3lOSmlzU1BRTHVQMWZsNVhvSThVRkNDNkY1RTlnTEkvLzd4OG5K?= =?utf-8?B?R0NUWStIUTMyTkJpS3JuSG1PRHNESU9uR3plWWdtODU0VHF2VytzRXRyeGNq?= =?utf-8?B?VUFDZXBxbEZQNXl0WTRxSHd2djlTdVFLdzBNbkhuZlgra1I0VUoreWpnbVdt?= =?utf-8?B?bzJPSktEUVUxWEFRRnBNbHZPb2hVQmM0aWxXNW9hZFJpeEtMejV5Y1ZYeDB2?= =?utf-8?B?N3Z3VGZzSUtBM2lSTzUvYzdJeHhDNTFieXY4ck0rUnhwOE1udWZFTXlpdm1B?= =?utf-8?B?MUwxQk9MUUpSMXFSb3RXQ3JrWjNaU21wZURMY2RXZjhmQ1M0RCtrTHp5UEVZ?= =?utf-8?B?RlRzeTM5cXc2OWsvZ203aTY2QWVUWStqQm9NU2FSZ2VLUXNTOGFqellyd0hn?= =?utf-8?B?TlBtMmMwSFF2N2dOM21jZTZ1L29LU01Cd1UyL1FTWXNKU3ZWWWExdzk5c202?= =?utf-8?B?ZVhZczBZdm1KV1FxUEpOQ1J0OFNaRERPaUVsMVAySE9OSWRGN3hadHM3TWh2?= =?utf-8?B?MDBUVTNGcU11ZHVUTHpBdmxPNkVQV1hzSUh1d1ZQbzlFUEs1UEtFY29sN3o3?= =?utf-8?B?dENtQ3d6eVJUNk1HMk92M1FDL3gwbUxlNXl4elYzSThEckdrYUQ1VVlBMFBy?= =?utf-8?B?UjlxcEMzMXRPYk42MS9kMG9BK1h5N1VTRXJrKytRTUR4eWRJeEpoWW5wK2tM?= =?utf-8?B?S1JuNCt0VldyaEFjSXdrMS9xUWJOV25lK2o4RTlDL0crSHlFTUxjU1QwVm5p?= =?utf-8?B?a1RTdHZCN01YNE9YQXBDelJhQ0FKakFPTWpqTEVYYVc3Yk94QkRmbG9qdjhS?= =?utf-8?B?dFVYQzhZV3B1c3JhdDRhZmZmT2o2ZWF6cjBtNmh4K2czcjQ1ZUI5R1U5Y2Q0?= =?utf-8?B?ZE14UldVNW5keEYxKzFlb3Z1cXBpZFA3dzBvdzZsemhPZWtlM1F4OFp4cWcy?= =?utf-8?B?VFZlK3ZqUWJlMVE4eFFSOE03L3kzM0VOTTdNa2ZWK2tpcW1BNFVQc1FjS0hy?= =?utf-8?B?eGJ0aktFcnlNd0xHV2dsM2lQNlNsK2YyalRsZkNLZHpMdXNlOXU4ME9FRFg1?= =?utf-8?B?eUhuVXZMOEVNM2pNckVsaDBnRTNYd0oyOWtQWW5oZXNrRTVvMHYzbjNQbXhy?= =?utf-8?B?SDZKTXlwVXFRUmhTYTJvOHZ3TW11MjlCYjJGSUxqR2p4R1pzVWJmZ2lTa3ha?= =?utf-8?B?bXZFb204VTlHL1g4L1VUd0tvNlQwSFJFNUVwZTBVRWxOTTZEVHppMHhoT0Ur?= =?utf-8?B?ekpsMEo1VEhtUEFrT2hKRldaQmtCbHloOXZxWlgzU3lFT0g3K1E1S21CWEt5?= =?utf-8?B?dUx1bkJtTU5TM2NReWVXMzIxSlRqcGZUcEc0WkswZVV5Q0o5R2ZKb1JaY0Rl?= =?utf-8?B?dm5McjBER3NDc2xiaXNxSmRtSzFmRS9sdTQrZ0IzTlFFcjZ1QjZFNTEyWUNu?= =?utf-8?Q?mCLFvsaWdbENENheNIXOpgOd+EBSHvmcEwAZQui?= X-OriginatorOrg: amd.com X-MS-Exchange-CrossTenant-Network-Message-Id: bbe2bcf0-b041-4f3b-9c9a-08d9889317d0 X-MS-Exchange-CrossTenant-AuthSource: DM6PR12MB3930.namprd12.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 06 Oct 2021 06:32:39.2042 (UTC) X-MS-Exchange-CrossTenant-FromEntityHeader: Hosted X-MS-Exchange-CrossTenant-Id: 3dd8961f-e488-4e60-8e11-a82d994e183d X-MS-Exchange-CrossTenant-MailboxType: HOSTED X-MS-Exchange-CrossTenant-UserPrincipalName: rQaPJYNjsmWyqJzl386V6LvQN/bEzyzz0opXasdiUrHjFUZYLu7ggcC2hvsHyu4n X-MS-Exchange-Transport-CrossTenantHeadersStamped: DM6PR12MB4356 X-BeenThere: dri-devel@lists.freedesktop.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Direct Rendering Infrastructure - Development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" On 10/6/2021 11:49 AM, Christian König wrote: > Am 06.10.21 um 06:51 schrieb Lazar, Lijo: >> >> >> On 10/5/2021 10:15 PM, Christian König wrote: >>> Am 05.10.21 um 15:49 schrieb Das, Nirmoy: >>>> >>>> On 10/5/2021 3:22 PM, Christian König wrote: >>>>> >>>>> >>>>> Am 05.10.21 um 15:11 schrieb Nirmoy Das: >>>>>> Debugfs core APIs will throw -EPERM when user disables debugfs >>>>>> using CONFIG_DEBUG_FS_ALLOW_NONE or with kernel param. We shouldn't >>>>>> see that as an error. Also validate drm root dentry before creating >>>>>> amdgpu debugfs files. >>>>>> >>>>>> Signed-off-by: Nirmoy Das >>>>>> --- >>>>>>   drivers/gpu/drm/amd/amdgpu/amdgpu_debugfs.c | 10 ++++++++++ >>>>>>   1 file changed, 10 insertions(+) >>>>>> >>>>>> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_debugfs.c >>>>>> b/drivers/gpu/drm/amd/amdgpu/amdgpu_debugfs.c >>>>>> index 6611b3c7c149..d786072e918b 100644 >>>>>> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_debugfs.c >>>>>> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_debugfs.c >>>>>> @@ -1617,6 +1617,16 @@ int amdgpu_debugfs_init(struct >>>>>> amdgpu_device *adev) >>>>>>       struct dentry *ent; >>>>>>       int r, i; >>>>>>   +    if (IS_ERR(root)) { >>>>>> +        /* When debugfs is disabled we get -EPERM which is not an >>>>>> +         * error as this is user controllable. >>>>>> +         */ >>>>> >>>>> Well setting primary->debugfs_root to an error code is probably not >>>>> a good idea to begin with. >>>>> >>>>> When debugfs is disabled that should most likely be NULL. >>>> >>>> >>>> If we set primary->debugfs_root to  NULL then we need to add bunch >>>> of NULL checks everywhere before creating any debugfs files >>>> >>>> because debugfs_create_{file|dir}() with NULL root is still valid. I >>>> am assuming a hypothetical case when debugfs_root dir creation fails >>>> even with debugfs enabled >>>> >>>> but further calls are successful.  This wont be a problem if we >>>> propagate the error code. >>> >>> Yeah, but an error code in members is ugly like hell and potentially >>> causes crashes instead. >>> >>> I strongly suggest to fix this so that root is NULL when debugfs >>> isn't available and we add proper checks for that instead. >> >> This shouldn't be done. A NULL is a valid parent for debugfs API. An >> invalid parent is always checked like this >>           if (IS_ERR(parent)) >>                 return parent; >> >> Instead of adding redundant work like NULL checks, let the API do its >> work and don't break the API contract. For ex: usage of sample client, >> you may look at the drm usage; it does the same. > > Yeah, but that is horrible API design and should be avoided. > > ERR_PTR(), PTR_ERR(), IS_ERR() and similar are supposed to be used as > alternative to signaling errors as return values from functions and > should *never* ever be used to signal errors in pointer members. > One escape route may be - add another export from debugfs like debugfs_is_valid_node() which adheres to the current logic in debugfs API and use that in client code. Whenever debugfs changes to a different logic from IS_ERR, let that be changed. Thanks, Lijo > Regards, > Christian. > >> >> Thanks, >> Lijo >> >>> >>> Regards, >>> Christian. >>> >>>> >>>> >>>> Regards, >>>> >>>> Nirmoy >>>> >>>>> >>>>> Regards, >>>>> Christian. >>>>> >>>>>> +        if (PTR_ERR(root) == -EPERM) >>>>>> +            return 0; >>>>>> + >>>>>> +        return PTR_ERR(ent); >>>>>> +    } >>>>>> + >>>>>>       ent = debugfs_create_file("amdgpu_preempt_ib", 0600, root, >>>>>> adev, >>>>>>                     &fops_ib_preempt); >>>>>>       if (IS_ERR(ent)) { >>>>> >>> >