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Wed, 26 Nov 2025 17:17:04 +0000 From: Aaron Tomlin To: tony.luck@intel.com, reinette.chatre@intel.com, Dave.Martin@arm.com, james.morse@arm.com, babu.moger@amd.com, tglx@linutronix.de, mingo@redhat.com, bp@alien8.de, dave.hansen@linux.intel.com Cc: dave.martin@arm.com, atomlin@atomlin.com, sean@ashe.io, linux-kernel@vger.kernel.org Subject: [PATCH 2/3] fs/resctrl: Return -EINVAL for a missing seq_show implementation Date: Wed, 26 Nov 2025 12:16:51 -0500 Message-ID: <20251126171653.1004321-3-atomlin@atomlin.com> X-Mailer: git-send-email 2.51.0 In-Reply-To: <20251126171653.1004321-1-atomlin@atomlin.com> References: <20251126171653.1004321-1-atomlin@atomlin.com> Content-Transfer-Encoding: quoted-printable X-ClientProxiedBy: BLAPR03CA0013.namprd03.prod.outlook.com (2603:10b6:208:32b::18) To CWLP123MB3523.GBRP123.PROD.OUTLOOK.COM (2603:10a6:400:70::10) 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: CWLP123MB3523:EE_|CWLP123MB6960:EE_ X-MS-Office365-Filtering-Correlation-Id: d0761fac-3c70-4513-dd06-08de2d0f9ea1 X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|376014|7416014|1800799024|366016; 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charset="utf-8" The rdtgroup_seqfile_show() function, which is the sequence file handler for reading data from resctrl files, previously returned 0 (success) if the file's associated rftype did not define a .seq_show implementation. This behavior is incorrect and confusing, as a read operation that does not define a display function should be treated as an error. This patch change the function to return -EINVAL if the file type handler (i.e., rft->seq_show) is NULL, providing proper feedback that the operation is invalid for that file. Signed-off-by: Aaron Tomlin --- fs/resctrl/rdtgroup.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/fs/resctrl/rdtgroup.c b/fs/resctrl/rdtgroup.c index 8e39dfda56bc..e1dc63b2218f 100644 --- a/fs/resctrl/rdtgroup.c +++ b/fs/resctrl/rdtgroup.c @@ -314,7 +314,8 @@ static int rdtgroup_seqfile_show(struct seq_file *m, vo= id *arg) =20 if (rft->seq_show) return rft->seq_show(of, m, arg); - return 0; + + return -EINVAL; } =20 static ssize_t rdtgroup_file_write(struct kernfs_open_file *of, char *buf, --=20 2.51.0