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=-0.9 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,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 4443EC606BD for ; Mon, 8 Jul 2019 17:30:48 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 1573B216FD for ; Mon, 8 Jul 2019 17:30:48 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=fb.com header.i=@fb.com header.b="YtjbrlQZ"; dkim=pass (1024-bit key) header.d=fb.onmicrosoft.com header.i=@fb.onmicrosoft.com header.b="J72ID1e6" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2388191AbfGHRaq (ORCPT ); Mon, 8 Jul 2019 13:30:46 -0400 Received: from mx0b-00082601.pphosted.com ([67.231.153.30]:45956 "EHLO mx0b-00082601.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728708AbfGHRaq (ORCPT ); Mon, 8 Jul 2019 13:30:46 -0400 Received: from pps.filterd (m0109332.ppops.net [127.0.0.1]) by mx0a-00082601.pphosted.com (8.16.0.27/8.16.0.27) with SMTP id x68HTDE5021381; Mon, 8 Jul 2019 10:29:53 -0700 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=fb.com; h=from : to : cc : subject : date : message-id : references : in-reply-to : content-type : content-id : content-transfer-encoding : mime-version; s=facebook; bh=x56FKSBgXOLvZMD+y3raguvfgHanfiop/tmf7yxKJYY=; b=YtjbrlQZ1KnjfbBOiHBpCkWxxlXu0WZ8e8LiV2iz/QSCTRBX4nOUMYB1ARsvrYmEaTRQ rohnfxxdCKGBlpzne6+IQ0oP6YNIxYdoOSWPtQn2yV5X4FDQcyXgr5Ht6XDT6Azpw+Fn x397Fd9PX3m85t6LqvHpus3MORRFLAId9l8= Received: from mail.thefacebook.com (mailout.thefacebook.com [199.201.64.23]) by mx0a-00082601.pphosted.com with ESMTP id 2tm7e30r61-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-SHA384 bits=256 verify=NOT); Mon, 08 Jul 2019 10:29:53 -0700 Received: from prn-hub03.TheFacebook.com (2620:10d:c081:35::127) by prn-hub05.TheFacebook.com (2620:10d:c081:35::129) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA384) id 15.1.1713.5; Mon, 8 Jul 2019 10:29:51 -0700 Received: from NAM01-SN1-obe.outbound.protection.outlook.com (192.168.54.28) by o365-in.thefacebook.com (192.168.16.27) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA384) id 15.1.1713.5 via Frontend Transport; Mon, 8 Jul 2019 10:29:51 -0700 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=fb.onmicrosoft.com; s=selector1-fb-onmicrosoft-com; h=From:Date:Subject:Message-ID:Content-Type:MIME-Version:X-MS-Exchange-SenderADCheck; bh=x56FKSBgXOLvZMD+y3raguvfgHanfiop/tmf7yxKJYY=; b=J72ID1e6yEPH/JQFvABF23eQcysYppP2uH5TKtl3nY3p/kNHZbyJ1ycd43oO93NckS3ZJNg1wu22xcpawtqMjlm2m+bS2jLv2Q+/k08LNz/ZukYuOO0FYMV/uiRygmzMJFLGYx6tOjwVzmeFOBlgwPfaPVSlEXyYU+tf7qXWcds= Received: from DM6PR15MB2635.namprd15.prod.outlook.com (20.179.161.152) by DM6PR15MB3737.namprd15.prod.outlook.com (10.141.167.27) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.2052.18; Mon, 8 Jul 2019 17:29:49 +0000 Received: from DM6PR15MB2635.namprd15.prod.outlook.com ([fe80::fc39:8b78:f4df:a053]) by DM6PR15MB2635.namprd15.prod.outlook.com ([fe80::fc39:8b78:f4df:a053%3]) with mapi id 15.20.2052.020; Mon, 8 Jul 2019 17:29:49 +0000 From: Roman Gushchin To: Tejun Heo CC: Peng Wang , "lizefan@huawei.com" , "hannes@cmpxchg.org" , "cgroups@vger.kernel.org" , "linux-kernel@vger.kernel.org" Subject: Re: [PATCH] cgroup: minor tweak for logic to get cgroup css Thread-Topic: [PATCH] cgroup: minor tweak for logic to get cgroup css Thread-Index: AQHVMUV9d2o/bgH9tUqXCEtcJHSYqabA9ciAgAANIwA= Date: Mon, 8 Jul 2019 17:29:49 +0000 Message-ID: <20190708172944.GA24662@tower.DHCP.thefacebook.com> References: <20190703020749.22988-1-rocking@whu.edu.cn> <20190708164243.GE657710@devbig004.ftw2.facebook.com> In-Reply-To: <20190708164243.GE657710@devbig004.ftw2.facebook.com> Accept-Language: en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: x-clientproxiedby: MWHPR08CA0021.namprd08.prod.outlook.com (2603:10b6:301:5f::34) To DM6PR15MB2635.namprd15.prod.outlook.com (2603:10b6:5:1a6::24) x-ms-exchange-messagesentrepresentingtype: 1 x-originating-ip: [2620:10d:c090:200::3b5d] x-ms-publictraffictype: Email x-ms-office365-filtering-correlation-id: 078aa51e-15cb-4730-33f4-08d703c9e0b1 x-microsoft-antispam: BCL:0;PCL:0;RULEID:(2390118)(7020095)(4652040)(8989299)(4534185)(4627221)(201703031133081)(201702281549075)(8990200)(5600148)(711020)(4605104)(1401327)(2017052603328)(7193020);SRVR:DM6PR15MB3737; x-ms-traffictypediagnostic: DM6PR15MB3737: x-microsoft-antispam-prvs: x-ms-oob-tlc-oobclassifiers: OLM:7219; x-forefront-prvs: 00922518D8 x-forefront-antispam-report: SFV:NSPM;SFS:(10019020)(136003)(376002)(366004)(346002)(39860400002)(396003)(189003)(199004)(81166006)(81156014)(54906003)(446003)(316002)(186003)(6246003)(476003)(76176011)(102836004)(4744005)(11346002)(99286004)(86362001)(68736007)(7736002)(53936002)(386003)(8936002)(305945005)(6116002)(6916009)(486006)(14454004)(46003)(8676002)(6506007)(256004)(73956011)(1076003)(4326008)(25786009)(6512007)(9686003)(71200400001)(64756008)(71190400001)(478600001)(66556008)(66446008)(66946007)(66476007)(5660300002)(2906002)(229853002)(6486002)(52116002)(33656002)(6436002);DIR:OUT;SFP:1102;SCL:1;SRVR:DM6PR15MB3737;H:DM6PR15MB2635.namprd15.prod.outlook.com;FPR:;SPF:None;LANG:en;PTR:InfoNoRecords;MX:1;A:1; received-spf: None (protection.outlook.com: fb.com does not designate permitted sender hosts) x-ms-exchange-senderadcheck: 1 x-microsoft-antispam-message-info: ZFZ7BDII4Bjyb4y5Tb8y/rFR7nl3tRchRCsKiuvfq2dtigaD/nsOtN9JjVvTkUmF0/opgNC7bTRUqV1WKdDJC1HLPdsm7v1TOrpA0jL3Y3JPK1XBr8zQxDF/O0kzN7w/laowc5V4+jCZbc01c23TlnBi/DuJcxBzyQm8VQ+o2uCiXt7D+RpTFDlhaxrn3zdrZqRaQjMNrcoSJyySMwT+SEBVJcCyUUU4DyJfl4tNpL6bW80Lj3sGlPLnBXUJHyn9bT5kNTZq5rUCk3No84prrOtJ/u0uzMQ2Bk2+1qFambPJC5StHvJfDs/rrtSa5uTJPI7X/2qTGkIo1zwgIYqzMGrJE7T0KlTMUk55cPccIUZKHf8YLPcdBDHYJBluni0UEh5jk30p0dgCicBeTlZZqHeIKL7q8hJ56QlCJB3EC7M= Content-Type: text/plain; charset="us-ascii" Content-ID: <1CF7146E8EDAE740858C66A1B5C99F4E@namprd15.prod.outlook.com> Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 X-MS-Exchange-CrossTenant-Network-Message-Id: 078aa51e-15cb-4730-33f4-08d703c9e0b1 X-MS-Exchange-CrossTenant-originalarrivaltime: 08 Jul 2019 17:29:49.2691 (UTC) X-MS-Exchange-CrossTenant-fromentityheader: Hosted X-MS-Exchange-CrossTenant-id: 8ae927fe-1255-47a7-a2af-5f3a069daaa2 X-MS-Exchange-CrossTenant-mailboxtype: HOSTED X-MS-Exchange-CrossTenant-userprincipalname: guro@fb.com X-MS-Exchange-Transport-CrossTenantHeadersStamped: DM6PR15MB3737 X-OriginatorOrg: fb.com X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:,, definitions=2019-07-08_05:,, signatures=0 X-Proofpoint-Spam-Details: rule=fb_default_notspam policy=fb_default score=0 priorityscore=1501 malwarescore=0 suspectscore=1 phishscore=0 bulkscore=0 spamscore=0 clxscore=1011 lowpriorityscore=0 mlxscore=0 impostorscore=0 mlxlogscore=793 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1810050000 definitions=main-1907080215 X-FB-Internal: deliver Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Jul 08, 2019 at 09:42:43AM -0700, Tejun Heo wrote: > On Wed, Jul 03, 2019 at 10:07:49AM +0800, Peng Wang wrote: > > We could only handle the case that css exists > > and css_try_get_online() fails. >=20 > As css_tryget_online() can't handle NULL input, this is a bug fix. > Can you please clarify that in the description? - if (!css || !css_tryget_online(css)) + if (css && !css_tryget_online(css)) If css =3D=3D NULL, !css is true, and the second part of the || statement will not be evaluated. So it's not a bug fix. Thanks!