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Content-Language: en-US To: Greg KH Cc: linux-kernel@vger.kernel.org, peterz@infradead.org, "Rafael J. Wysocki" References: <20230530194012.44411-1-chris.hyser@oracle.com> <2023053025-blinks-vexingly-60d3@gregkh> From: chris hyser In-Reply-To: <2023053025-blinks-vexingly-60d3@gregkh> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-ClientProxiedBy: MN2PR18CA0001.namprd18.prod.outlook.com (2603:10b6:208:23c::6) To CO1PR10MB4705.namprd10.prod.outlook.com (2603:10b6:303:96::11) MIME-Version: 1.0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: CO1PR10MB4705:EE_|SA2PR10MB4794:EE_ X-MS-Office365-Filtering-Correlation-Id: 73092a90-269e-45a9-dc77-08db6156a307 X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0; X-Microsoft-Antispam-Message-Info: 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73092a90-269e-45a9-dc77-08db6156a307 X-MS-Exchange-CrossTenant-AuthSource: CO1PR10MB4705.namprd10.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 30 May 2023 21:41:33.5365 (UTC) X-MS-Exchange-CrossTenant-FromEntityHeader: Hosted X-MS-Exchange-CrossTenant-Id: 4e2c6054-71cb-48f1-bd6c-3a9705aca71b X-MS-Exchange-CrossTenant-MailboxType: HOSTED X-MS-Exchange-CrossTenant-UserPrincipalName: 83XQG82loCqdxQSv2edR7CSHL5wO7HVZU9CX5Ll4sx15KqZwNuaDCVRRrUY7ZnrEwhcIf9GnaPsE3DVkWtDTSA== X-MS-Exchange-Transport-CrossTenantHeadersStamped: SA2PR10MB4794 X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.254,Aquarius:18.0.957,Hydra:6.0.573,FMLib:17.11.176.26 definitions=2023-05-30_16,2023-05-30_01,2023-05-22_02 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 spamscore=0 malwarescore=0 phishscore=0 bulkscore=0 adultscore=0 mlxscore=0 suspectscore=0 mlxlogscore=999 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2304280000 definitions=main-2305300176 X-Proofpoint-ORIG-GUID: wkVUXvHWC0GUaKT8VPIjSevo_GCpWNHB X-Proofpoint-GUID: wkVUXvHWC0GUaKT8VPIjSevo_GCpWNHB Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 5/30/23 16:18, Greg KH wrote: > On Tue, May 30, 2023 at 03:40:08PM -0400, chris hyser wrote: >> v2: >> Apologies. I sent this the first time without including lkml. >> >> v1: >> This originally started as an attempt to solve a divide by zero issue in sched >> debug code that was introduced when a sysctl value with non-zero checking was >> moved to a simple u32 debugfs file. In looking at ways to solve this, it was >> mentioned I should look at providing general debugfs files with min/max >> checking. >> >> One problem was that a check for greater than zero for say a u8 succeeds for a >> number like 256 (but stores a zero anyway) as the upper bits that don't fit into >> storage are silently dropped. Therefore values greater than the storage capacity >> must also fail. Getting an error when what the user wrote is not what was >> actually stored, seems like a useful requirement for the other simple files and >> so I moved the check into there. >> >> To enable easy testing, a test module and test script are provided which can >> validate the new functions as well as check the new limits on the older >> functions. This was stuck under selftests, but it is not currently tied into the >> testing infrastructure. > > This is a lot of new infrastructure for a single debugfs file that you > could just check for in the file write callback instead. > > I'm all for cool new features, but wow, this seems like major overkill. > Are you _SURE_ you need it all? The current use case obviously does not require all of this. The idea was instead of a one off fix, it might be useful to provide a generic solution to a common class of problems. So sending this out hopefully would help determine the perceived usefulness. -chrish