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Thu, 13 Aug 2026 18:23:58 +0000 Message-ID: <2d467216-db52-47a0-baaa-b6d4f9c99268@intel.com> Date: Thu, 13 Aug 2026 11:23:55 -0700 User-Agent: Mozilla Thunderbird Subject: Re: [RESEND PATCH v4 08/15] fs/resctrl: Add interface to display supported and active kernel-mode policy To: Babu Moger , "Moger, Babu" , , , , , , , , CC: , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , References: <328e237e-3d26-47c0-8167-8ffe5d765daf@intel.com> <924aedc6-c2dc-4c09-84d5-2bdf1370ab36@amd.com> <24adc700-2062-44d1-92f3-4bc18d134b8d@intel.com> From: Reinette Chatre Content-Language: en-US In-Reply-To: Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 8bit X-ClientProxiedBy: MW4PR04CA0378.namprd04.prod.outlook.com (2603:10b6:303:81::23) To SJ2PR11MB8370.namprd11.prod.outlook.com (2603:10b6:a03:540::20) Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: SJ2PR11MB8370:EE_|MN2PR11MB4584:EE_ X-MS-Office365-Filtering-Correlation-Id: 843ec447-9615-4ecb-7a22-08def9680acc 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;ARA:13230040|366016|23010399003|376014|7416014|1800799024|921020|10067099003|56012099006|11063799006|4143699003|22082099003|18002099003; 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>>>>> +        if (!rdtgrp) { >>>>> +            ret = -ENOENT; >>>>> +            goto out_unlock; >>>> >>>> If this fails there needs to be content in last_cmd_status. Otherwise this >>>> fails and then last_cmd_status reads "ok" or worse .. an old failure message. >>> >>> if (WARN_ON(!rdtgrp)) { >>>      rdt_last_cmd_puts("Invalid kernel mode group\n"); >>>      ret = -ENOENT; >>>      goto out_unlock; >>> } >> It is not clear to me why the WARN_ON() was added. Is the resource group not being >> associated with kernel mode not a legitimate scenario if the kernel mode group was >> re-assigned while the reader of this file was blocked on the mutex? >> > A valid group is required whenever any global mode is enabled. > Reaching this condition without one is unexpected and should be > treated as a bug. > > To help catch this, I added a WARN_ON() to log the issue. I think > updating last_cmd_status is reasonable as well and should provide > the necessary user-visible error indication. ah - thanks. I misread this snippet as an interaction with a resource group's files. Reinette