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Petersen" , linux-scsi@vger.kernel.org Subject: Re: [PATCH 03/14] scsi: core: Do not truncate INQUIRY data on modern devices From: "Martin K. Petersen" Organization: Oracle Corporation Message-ID: References: <20220302053559.32147-1-martin.petersen@oracle.com> <20220302053559.32147-4-martin.petersen@oracle.com> <82c21426-4d23-1e5f-ef9b-212d623eb8f7@acm.org> Date: Thu, 03 Mar 2022 22:40:42 -0500 In-Reply-To: <82c21426-4d23-1e5f-ef9b-212d623eb8f7@acm.org> (Bart Van Assche's message of "Wed, 2 Mar 2022 16:14:44 -0800") Content-Type: text/plain X-ClientProxiedBy: SA9PR10CA0025.namprd10.prod.outlook.com (2603:10b6:806:a7::30) To CO1PR10MB4754.namprd10.prod.outlook.com (2603:10b6:303:91::24) MIME-Version: 1.0 X-MS-PublicTrafficType: Email X-MS-Office365-Filtering-Correlation-Id: 41ad079e-49bf-40c4-f180-08d9fd90c32b X-MS-TrafficTypeDiagnostic: DM5PR10MB1497:EE_ X-Microsoft-Antispam-PRVS: 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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 X-Forefront-Antispam-Report: CIP:255.255.255.255;CTRY:;LANG:en;SCL:1;SRV:;IPV:NLI;SFV:NSPM;H:CO1PR10MB4754.namprd10.prod.outlook.com;PTR:;CAT:NONE;SFS:(13230001)(366004)(6512007)(186003)(26005)(38350700002)(5660300002)(38100700002)(6486002)(2906002)(83380400001)(508600001)(8936002)(86362001)(316002)(6916009)(66556008)(66946007)(6506007)(66476007)(4326008)(8676002)(52116002)(36916002);DIR:OUT;SFP:1101; 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I'm asking this because the number of LLDs that sets > inquiry_len is small: > > $ git grep -nH '>inquiry_len[[:blank:]]*=[[:blank:]]'|grep -v scsi_scan > drivers/firewire/sbp2.c:1508: sdev->inquiry_len = 36; > drivers/staging/rts5208/rtsx.c:67: sdev->inquiry_len = 36; > drivers/usb/image/microtek.c:323: s->inquiry_len = 0x24; > drivers/usb/storage/scsiglue.c:77: sdev->inquiry_len = 36; > > Does any of these LLDs support SPC-4 devices? Can this change > e.g. break support for certain USB sticks? The intent is to enable more modern protocol features on devices attached using USB. I was concerned about blindly increasingly the inquiry length and risk breaking older devices that we know are likely to have problems in this department. At the same time the conservative clamp on the inquiry length prevents several useful features from being enabled on modern devices. There is a risk associated with any change. This patch tries to strike a reasonable balance between avoiding regressions and accommodating modern USB SSDs. -- Martin K. Petersen Oracle Linux Engineering