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Wysocki" CC: "lenb@kernel.org" , "gregkh@linuxfoundation.org" , "robert.moore@intel.com" , "erik.schmauss@intel.com" , "linux-acpi@vger.kernel.org" , "linux-kernel@vger.kernel.org" , Joey Lee , "mhocko@kernel.org" Subject: Re: [RFC PATCH v2 1/3] ACPI / hotplug: Send change events for offline/online requests when eject is triggered Message-ID: <20200313082026.GA4725@linux-8mug> References: <20200103043926.31507-1-clin@suse.com> <20200103043926.31507-2-clin@suse.com> <1702691.vqsIMzBuNn@kreacher> Content-Type: text/plain; charset="us-ascii" Content-Disposition: inline In-Reply-To: <1702691.vqsIMzBuNn@kreacher> User-Agent: Mutt/1.12.2 (2019-09-21) X-ClientProxiedBy: LO2P265CA0011.GBRP265.PROD.OUTLOOK.COM (2603:10a6:600:62::23) To SN1PR18MB2126.namprd18.prod.outlook.com (2603:10b6:802:29::29) MIME-Version: 1.0 X-MS-Exchange-MessageSentRepresentingType: 1 Received: from linux-8mug (111.249.38.188) by LO2P265CA0011.GBRP265.PROD.OUTLOOK.COM (2603:10a6:600:62::23) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.2814.16 via Frontend Transport; Fri, 13 Mar 2020 08:21:59 +0000 X-Originating-IP: [111.249.38.188] X-MS-PublicTrafficType: Email X-MS-Office365-Filtering-Correlation-Id: d5cf9cdf-eacb-4daf-3d7f-08d7c7279bd2 X-MS-TrafficTypeDiagnostic: SN1PR18MB2334: X-MS-Exchange-Transport-Forked: True X-Microsoft-Antispam-PRVS: X-MS-Oob-TLC-OOBClassifiers: OLM:9508; X-Forefront-PRVS: 034119E4F6 X-Forefront-Antispam-Report: SFV:NSPM;SFS:(10019020)(4636009)(39860400002)(346002)(376002)(366004)(136003)(396003)(199004)(53546011)(2906002)(81166006)(52116002)(8676002)(6496006)(54906003)(478600001)(8936002)(66476007)(66556008)(81156014)(6916009)(66946007)(316002)(33716001)(4326008)(16526019)(186003)(6666004)(9686003)(55016002)(956004)(1076003)(86362001)(33656002)(5660300002)(26005);DIR:OUT;SFP:1102;SCL:1;SRVR:SN1PR18MB2334;H:SN1PR18MB2126.namprd18.prod.outlook.com;FPR:;SPF:None;LANG:en;PTR:InfoNoRecords;A:1; Received-SPF: None (protection.outlook.com: suse.com does not designate permitted sender hosts) X-MS-Exchange-SenderADCheck: 1 X-Microsoft-Antispam: BCL:0; X-Microsoft-Antispam-Message-Info: DYBgRGT90xJEYccVNcE76zyfwliPtUsgs58hWJbXjZ+yQCfFL8+6lchPejtpZny+OLcmhpXohoHSiNr6N16tO3m4QMwJrJxXSoY55McoSMwtn3bvDIlVX2EEXU5EAPFDjUoUAYIjMlPx4L7rVzq/BgSlKJ0GZ37a3QwXcYzNziNW/Nm6M8BNAM0WoOZ4ui/9on62WJQQydJvDKNhm5QLM11cSRWrKJuvb7ppuVQYqVzff6g6JJKhRozEwEP2Vxis29vUB6R5lwKkSOnBd3CLPg+W/TEuZMqZuC4wfXbb2HWlozmA4MKJMghWUISGU7HSmBiC7z9slJrpEX9lHmih6M7jJWg5vwkU8BEKSinjwQc7I78YmoODFQKe5Qv6obfGhmLcwmYEvnwhIp/wz0tjOVTcF2i28hGAn5W8DE90Y0IzWWogcdkGEY7jaeULmHgC X-MS-Exchange-AntiSpam-MessageData: JX9t1hgeAOV6+MDEK9iqbOxiYJo/DrNpkfAf+kkwS3XkCphpaH+vgh1lpOWlxH4JbVwwPV20MmmM69hcb2Tj9Xs3Jduo425Jl80QjRnszphvk/oFov/qNa0hIhGix6VosHb2ZM7R3xh/s81lAp/5nw== X-MS-Exchange-CrossTenant-Network-Message-Id: d5cf9cdf-eacb-4daf-3d7f-08d7c7279bd2 X-MS-Exchange-CrossTenant-OriginalArrivalTime: 13 Mar 2020 08:22:04.1365 (UTC) X-MS-Exchange-CrossTenant-FromEntityHeader: Hosted X-MS-Exchange-CrossTenant-Id: 856b813c-16e5-49a5-85ec-6f081e13b527 X-MS-Exchange-CrossTenant-MailboxType: HOSTED X-MS-Exchange-CrossTenant-UserPrincipalName: feLljllCVy2hfUQaFqYeHuJ7eXTjTWgxfXaL99QBFGGLR+sVz1mRms7qeYEdYGi/ X-MS-Exchange-Transport-CrossTenantHeadersStamped: SN1PR18MB2334 X-OriginatorOrg: suse.com Sender: linux-acpi-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-acpi@vger.kernel.org Hi Rafael, On Wed, Jan 15, 2020 at 11:15:08AM +0100, Rafael J. Wysocki wrote: > On Friday, January 3, 2020 5:40:09 AM CET Chester Lin wrote: > > Here we change offline/online handling in device hotplug by sending change > > events to userland as notification so that userland can have control and > > determine when will be a good time to put them offline/online based on > > current workload. In this approach the real offline/online opertions are > > handed over to userland so that userland can have more time to prepare > > before any device change actually happens. > > > > All child devices under the ejection target are traversed and notified > > hierarchically based on ACPI namespace in ascending order when an eject > > event happens. > > > > Signed-off-by: Chester Lin > > So you replace the old flow with the new one and make the new one mandatory AFAICS. > > Thus if anyone has relied on the old flow, they now need to switch over. > > This is unfriendly and generally unwelcome, so please avoid making changes like > that. > Thank you for the reminder. > Instead, I would consider adding a device attribute to allow user space to > opt in for getting offline notifications for specific individual devices (by > setting that attribute user space would tell the kernel that it wants to > get offline notifications for the device in question and it would take > care of offlining it as needed). > Thanks for your advice. If no one is working on this device attribute [please free feel to correct me if I'm wrong], I am willing to implement it and will send a new RFC patch for code review. Regards, Chester