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Mon, 20 Nov 2023 17:04:40 +0000 Message-ID: Date: Mon, 20 Nov 2023 10:04:37 -0700 User-Agent: Betterbird (Linux) Subject: Re: [PATCH v3] cxl: Add cxl_region_rwsem around commit_end write during decoder enumeration To: Davidlohr Bueso CC: , , , , , , References: <170025232811.2147250.16376901801315194121.stgit@djiang5-mobl3> Content-Language: en-US From: Dave Jiang In-Reply-To: Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit X-ClientProxiedBy: BY5PR16CA0021.namprd16.prod.outlook.com (2603:10b6:a03:1a0::34) To PH7PR11MB5984.namprd11.prod.outlook.com (2603:10b6:510:1e3::15) 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: PH7PR11MB5984:EE_|SA3PR11MB7526:EE_ X-MS-Office365-Filtering-Correlation-Id: 15af59d6-2241-492a-2bfb-08dbe9eac8f3 X-LD-Processed: 46c98d88-e344-4ed4-8496-4ed7712e255d,ExtAddr X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0; 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An assert splat emitted by cxl_num_decoders_committed(). >> However looking at the code, it looks like the write version of the rwsem >> needs to be taken due to the modification of commit_end. Wrap the write >> version of the rwsem around reading and writing of commit_end. >> >> Fixes: 176baefb2eb5 ("cxl/hdm: Commit decoder state to hardware") >> Signed-off-by: Dave Jiang > > Uhmm but do we expect concurrency during the switch/port probing phase? I would assume so, which makes the protection necessary no? > > Thanks, > Davidlohr