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Tue, 3 Feb 2026 21:14:37 +0000 From: Date: Tue, 3 Feb 2026 13:14:35 -0800 To: Li Ming , Jonathan Cameron CC: dave , dave.jiang , alison.schofield , vishal.l.verma , ira.weiny , dan.j.williams , linux-cxl , linux-kernel Message-ID: <6982653bdfcbc_68d310065@dwillia2-mobl4.notmuch> In-Reply-To: <19c23e33320.c78951ef7300.3027465952765956716@zohomail.com> References: <20260201093002.1281858-1-ming.li@zohomail.com> <20260201093002.1281858-3-ming.li@zohomail.com> <20260202153924.00002396@huawei.com> <19c23e33320.c78951ef7300.3027465952765956716@zohomail.com> Subject: Re: [PATCH 2/2] cxl/core: Hold grandparent port lock while dport adding Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit X-ClientProxiedBy: BY5PR03CA0028.namprd03.prod.outlook.com (2603:10b6:a03:1e0::38) To PH8PR11MB8107.namprd11.prod.outlook.com (2603:10b6:510:256::6) Precedence: bulk X-Mailing-List: linux-cxl@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: PH8PR11MB8107:EE_|MW4PR11MB7128:EE_ X-MS-Office365-Filtering-Correlation-Id: dd36b2f5-9373-4884-0f09-08de63693cc0 X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|376014|1800799024|366016; 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For unregister_port() > > (which is easier to track down that the add path locking) the lock > > taken depends on where the port is that is being unregistered. > > Specifically root ports are unregistered under parent->uport_dev, not > > parent->dev. > You are right. > When cxl acpi driver attempts to add a cxl host bridge port, it will hold cxl_root->uport_dev. > Otherwide, hold parent_port->dev lock for the new port addition. > So I think it is possible that memdev can observe a cxl host bridge port but it has not been attach yet. > Maybe I should hold the lock of the new port's host. > Let's see if other reviewers have more comments on that. So, I think current code is ok, if cxl_mem_probe() races cxl_acpi_probe() in the same way that case is already caught by the cxl_bus_rescan() at the end of cxl_acpi_probe().