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Thu, 29 May 2025 20:55:24 +0000 Date: Thu, 29 May 2025 13:55:21 -0700 From: Dan Williams To: , Davidlohr Bueso , Jonathan Cameron , Dave Jiang , Vishal Verma , Ira Weiny , Dan Williams CC: , Alok Tiwari Subject: Re: [PATCH] cxl/pci: Replace mutex_lock_io() w mutex_lock() for mailbox access Message-ID: <6838c9b94d05_3e70100e7@dwillia2-xfh.jf.intel.com.notmuch> References: <20250529205117.1990465-1-alison.schofield@intel.com> Content-Type: text/plain; charset="us-ascii" Content-Disposition: inline In-Reply-To: <20250529205117.1990465-1-alison.schofield@intel.com> X-ClientProxiedBy: BY5PR03CA0007.namprd03.prod.outlook.com (2603:10b6:a03:1e0::17) 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_|DM3PPF5EA507B64:EE_ X-MS-Office365-Filtering-Correlation-Id: 6f989e74-8fa3-4430-2b83-08dd9ef32212 X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|1800799024|366016|376014; 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X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: =?us-ascii?Q?OpBqSNIZqe8QE5AEDkBk/MXY2FixT2E0BlEyIkxbhRWYorJRvIJsPyDI9rgF?= =?us-ascii?Q?v28f3Q/aNQWPDn3E2Vp/+lTGVQxarVTGZeRgFMMXGwPo7HqbqwawUzF7zzvo?= =?us-ascii?Q?Eb6wnXMHqRMSmqrIg++y5xBjrMH0g76mEe4+9yQCjCywaYY/KeQ6heawGD7c?= =?us-ascii?Q?7GRb+kwLHgIUinEauPzNppojYWak1cX/DJisHpGOVe5Sq07uQpS4bUoXeyae?= =?us-ascii?Q?Cdi2zhvmHMbvUfNZMffp7xNuzX60wNxC8bGlF/2Emr0bUcvGhmg592Phi+7x?= =?us-ascii?Q?KJHqH85t7t59j0rQ09Kin47j3Nt3kXmyF1PZMlBc8xCzkLVvZhJ6nLSRx6gI?= =?us-ascii?Q?7rylxAO618s7Ez4qv61fXqjt+2yoMgTL79gomiigtIYvgCW/Gp1pQU3WO7As?= =?us-ascii?Q?Xbv0bqgNaFQNKk/A2oJVjZOSU5UVAqflefBcM6L0UdF0no5rq9ZHssu94N/o?= =?us-ascii?Q?1Ntd6x5lsQEcXUn8fFlA4HBXDWN/rZxOlR1utM6KGDmb8zr5xHCZ0LGEHM9P?= =?us-ascii?Q?2qDwrQemNn2skeX07bnIckhr9u/cFGGLsjrEhIyq9s7exMvkoLuswg1uXpD3?= =?us-ascii?Q?pK5fP3YNQH22INA3JgGUyIiWVI9vXRwa9Ls6yf/9VLjb/iWABaboXbUgDXbf?= =?us-ascii?Q?E/H7LTQhMn4dgx2o0hwBgymVxm1yz28x4ZynMI/RRDc4KKP1OudHNkSjnqew?= =?us-ascii?Q?uwdCimwjQHVEMr7auZ7PUwwG0AQyoDG8POkddZ4juLX4HZLB0qXDU6apnFjC?= =?us-ascii?Q?ACycBj/u0rCMic/1VjCWpULbVOGWskbcVqsX0xyWhfQfniFzgsM9xjdrmdkA?= =?us-ascii?Q?xrCrPc6agprDJWDG3cmLYLkIxUNlspBLfxxeEsVI/d3dawg3fPceKTZ8lO1H?= =?us-ascii?Q?oK+KMNZT68zdlwWcLM7HBWlKGDVOKu7rk2y/YW1RUNgS9ReNYhRD6ZadYTLH?= =?us-ascii?Q?Qw1iaLL+r7NjAIV6hU5yzKxtpvQrHgmUgHD/FAjddGFMPHngUi1n436y87PD?= =?us-ascii?Q?WMmNA5ZpEESMIoDhBVLlrHdnOBxOdWXeKAZOvnnE2PQU63OzbB4cAQzKF9QZ?= =?us-ascii?Q?c3b7d8gOzirm28HAnClbVf8N6ESQFLknfBhSwuqzqZePweaf6hXhbnLMMp96?= =?us-ascii?Q?D1Ajp9kHsJHnCmYujPedrpf6JaQh9BdzX45n1heTtE6C8VpoKZJXUqHXJhz8?= =?us-ascii?Q?kw+PYCxlQw0q5CeHdcsOi3YRgCHX/TY+Qvv+Ik9Ogn1XWwI544ae2RQpKNZY?= =?us-ascii?Q?ytAOcqVYVjKTFGyjAb9YtwCXkJ4G2a6syDMTrc5iMx2SRGX/m/+0xYWyx/Hw?= =?us-ascii?Q?c+MQIYpnhokxL9c2AmfT+kngwu2BMIzrvMVGpbQhijtoBkRzEyAmtMGtAAC+?= =?us-ascii?Q?T8Civ8Qp0iEtLH3PGERtQDviNXt/4F75oNLfiE/YDIkjPsq+ki2sA32mK4k7?= =?us-ascii?Q?hMNbq6q6KFqoeUZqaHX8xLDxGCygrUezoOsUt6TqfelOz7aCwrgPzz5iH1yb?= =?us-ascii?Q?xI5k1xFvbh5A6kGynHfqgmUqSXHM93hk/cEhfnr+J/PqmzcJKfrEV35Ai17R?= =?us-ascii?Q?nKu/VnOgZiHKBm6PNwxUyzAiQAQVB6cw6DrR28d50325n2Txwui8qWn+vpgN?= =?us-ascii?Q?Wg=3D=3D?= X-MS-Exchange-CrossTenant-Network-Message-Id: 6f989e74-8fa3-4430-2b83-08dd9ef32212 X-MS-Exchange-CrossTenant-AuthSource: PH8PR11MB8107.namprd11.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 29 May 2025 20:55:24.3545 (UTC) X-MS-Exchange-CrossTenant-FromEntityHeader: Hosted X-MS-Exchange-CrossTenant-Id: 46c98d88-e344-4ed4-8496-4ed7712e255d X-MS-Exchange-CrossTenant-MailboxType: HOSTED X-MS-Exchange-CrossTenant-UserPrincipalName: fS9h3nCInap+7qCVa8BzUbjqXkYvAfhPoI5r+SwOv9mo+HCTIABVpdzJ4m3jNz0B8FZfdVejq0+jc0MYoIRN0Fc9MZZTMyarg0SpwePwkXs= X-MS-Exchange-Transport-CrossTenantHeadersStamped: DM3PPF5EA507B64 X-OriginatorOrg: intel.com alison.schofield@ wrote: > From: Alison Schofield > > mutex_lock_io() differs from mutex_lock() in that it may call > io_schedule() when a task must sleep waiting for the lock. This > distinction only makes sense in block I/O or memory reclaim paths, > where giving I/O a chance to make progress is useful. > > At this call site, cxl_pci_mbox_send(), the mutex protects an MMIO > mailbox. The task holding the lock is not blocking I/O progress, so > calling io_schedule(), as mutex_lock_io() may do, has no practical > effect. > > Although there is no functional change, using the correct locking > primitive, that more accurately reflects the semantics and intended > use of the lock, improves code clarity and avoids misleading readers > and tools. > > Reported-by: Alok Tiwari > Closes: https://lore.kernel.org/linux-cxl/0d2af1e8-7f1b-438c-a090-fd366c8c63e0@oracle.com/ > Suggested-by: Dan Williams > Fixes: 8adaf747c9f0 ("cxl/mem: Find device capabilities") > Signed-off-by: Alison Schofield Looks good to me, I would suggest that Dave drop the Fixes: tag on applying since there is no need to backport this. Reviewed-by: Dan Williams