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Sat, 4 Apr 2026 00:03:30 +0000 Message-ID: <7fe71e6c-e447-4aac-aac8-30941e755209@intel.com> Date: Fri, 3 Apr 2026 17:03:28 -0700 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v4 3/7] fs/resctrl: Add interface to disable a monitor event To: Tony Luck , Fenghua Yu , "Maciej Wieczor-Retman" , Peter Newman , James Morse , Babu Moger , Drew Fustini , Dave Martin , Chen Yu , David E Box , CC: , References: <20260330214322.96686-1-tony.luck@intel.com> <20260330214322.96686-4-tony.luck@intel.com> Content-Language: en-US From: Reinette Chatre In-Reply-To: <20260330214322.96686-4-tony.luck@intel.com> Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit X-ClientProxiedBy: MW4PR04CA0137.namprd04.prod.outlook.com (2603:10b6:303:84::22) To SJ2PR11MB7573.namprd11.prod.outlook.com (2603:10b6:a03:4d2::10) Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: SJ2PR11MB7573:EE_|PH0PR11MB4952:EE_ X-MS-Office365-Filtering-Correlation-Id: 4aec3367-7629-4c4c-c6ad-08de91dd9ab8 X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|366016|376014|1800799024|921020|56012099003|22082099003|18002099003; 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But there > is no way to clean up and disable events. Missing why it is required to disable events. > > Add resctrl_disable_mon_event(). (can be seen from patch) > Adding/removing events is only > possible when the file system is not mounted. Add a WARN_ON() to While this is accurate that it should not be possible to enable/disable events while resctrl is mounted, this is *not* the *only* time when it should not be possible. Here it is unfortunately not straight forward since only some events require per-domain state which requires the event to be enabled before any domain comes online, potentially very early in initialization. To me the addition of this warning adds false security. Also, consider that resctrl_mounted is protected by rdtgroup_mutex and this addition gives architecture code free access without any protection. To do this right resctrl may need to add more state to an event but how that may look is unclear since an architecture may require per-domain architectural state for an event while resctrl fs needs none. At this time these scenarios may just fall into the "architecture must do the right thing" category since it has best information on how state is managed for the events as they are enabled/disabled. Reinette