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Tue, 8 May 2018 04:40:01 -0400 Received: from mail-pl0-f48.google.com ([209.85.160.48]:39720 "EHLO mail-pl0-f48.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932540AbeEHIj7 (ORCPT ); Tue, 8 May 2018 04:39:59 -0400 X-Google-Smtp-Source: AB8JxZqTKjKry9jJ4OWhZ2Dj+j9F3sgjE3+VvaPHluguAanakdz67iE/5qZ6vgLkUNyo/krkquVv+Q== Subject: Re: [usb-storage] [PATCH] usb: storage: Fix a possible data race in uas_queuecommand_lck To: Oliver Neukum , stern@rowland.harvard.edu, gregkh@linuxfoundation.org Cc: linux-usb@vger.kernel.org, linux-scsi@vger.kernel.org, usb-storage@lists.one-eyed-alien.net, linux-kernel@vger.kernel.org References: <20180508074743.13622-1-baijiaju1990@gmail.com> <1525768070.24345.8.camel@suse.com> From: Jia-Ju Bai Message-ID: <37706c9a-8b12-8440-29fd-34342e47a68e@gmail.com> Date: Tue, 8 May 2018 16:39:50 +0800 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:52.0) Gecko/20100101 Thunderbird/52.2.0 MIME-Version: 1.0 In-Reply-To: <1525768070.24345.8.camel@suse.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit Content-Language: en-US Sender: linux-usb-owner@vger.kernel.org X-Mailing-List: linux-usb@vger.kernel.org X-getmail-retrieved-from-mailbox: INBOX X-Mailing-List: linux-kernel@vger.kernel.org List-ID: On 2018/5/8 16:27, Oliver Neukum wrote: > Am Dienstag, den 08.05.2018, 15:47 +0800 schrieb Jia-Ju Bai: >> The write operations to "cmnd->result" and "cmnd->scsi_done" >> are protected by the lock on line 642-643, but the write operations >> to these data on line 634-635 are not protected by the lock. >> Thus, there may exist a data race for "cmnd->result" >> and "cmnd->scsi_done". > No, > > the write operations need no lock. The low level driver at this point > owns the command. We cannot race with abort() for a command within > queuecommand(). We take the lock where we take it to protect > dev->resetting. > > I don't see why the scope of the lock would need to be enlarged. Okay, thanks for your reply and explanation. Best wishes, Jia-Ju Bai