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Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.13.0 Subject: Re: [PATCH] USB:bugfix a controller halt error Content-Language: en-US To: Alan Stern , liulongfang Cc: gregkh@linuxfoundation.org, linux-usb@vger.kernel.org, linux-kernel@vger.kernel.org References: <20230721100015.27124-1-liulongfang@huawei.com> From: Oliver Neukum In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-ClientProxiedBy: FR2P281CA0057.DEUP281.PROD.OUTLOOK.COM (2603:10a6:d10:93::17) To VI1PR04MB7104.eurprd04.prod.outlook.com (2603:10a6:800:126::9) MIME-Version: 1.0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: VI1PR04MB7104:EE_|AM9PR04MB7569:EE_ X-MS-Office365-Filtering-Correlation-Id: 03395b4e-a219-4152-3c94-08db8c427440 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:VI1PR04MB7104.eurprd04.prod.outlook.com;PTR:;CAT:NONE;SFS:(13230028)(366004)(396003)(346002)(136003)(376002)(39860400002)(451199021)(31686004)(2906002)(4326008)(6486002)(4744005)(36756003)(8676002)(41300700001)(316002)(66476007)(66556008)(66946007)(110136005)(478600001)(38100700002)(6512007)(53546011)(186003)(8936002)(86362001)(31696002)(5660300002)(2616005)(6506007)(43740500002)(45980500001);DIR:OUT;SFP:1101; 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It is made before we know the actual maxpacket size for ep0, > and as a result it might return an error code even when it works okay. > This shouldn't happen, but a lot of USB hardware is unreliable. > > Therefore we must not ignore the result merely because r < 0. If we do > that, the kernel might stop working with some devices. Right. However, we must make sure we are operating on controlled results. As is we are operating on a random buffer without checking an IO operation has been performed on it. Regards Oliver