From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932934AbeCFOoC (ORCPT ); Tue, 6 Mar 2018 09:44:02 -0500 Received: from aserp2130.oracle.com ([141.146.126.79]:54698 "EHLO aserp2130.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753785AbeCFOjm (ORCPT ); Tue, 6 Mar 2018 09:39:42 -0500 Subject: Re: [PATCH V4] scsi: core: use blk_mq_requeue_request in __scsi_queue_insert To: jejb@linux.vnet.ibm.com, martin.petersen@oracle.com Cc: Bart.VanAssche@wdc.com, linux-scsi@vger.kernel.org, linux-kernel@vger.kernel.org, Christoph Hellwig References: <1520042049-8874-1-git-send-email-jianchao.w.wang@oracle.com> From: "jianchao.wang" Message-ID: <46a8136a-3dbb-0b73-4dfe-2a44a860dbe7@oracle.com> Date: Tue, 6 Mar 2018 22:39:38 +0800 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.6.0 MIME-Version: 1.0 In-Reply-To: <1520042049-8874-1-git-send-email-jianchao.w.wang@oracle.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit X-Proofpoint-Virus-Version: vendor=nai engine=5900 definitions=8823 signatures=668683 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 suspectscore=0 malwarescore=0 phishscore=0 bulkscore=0 spamscore=0 mlxscore=0 mlxlogscore=999 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1711220000 definitions=main-1803060165 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Martin Can you take your precious time to review this ? Thanks in advice. Jianchao On 03/03/2018 09:54 AM, Jianchao Wang wrote: > In scsi core, __scsi_queue_insert should just put request back on > the queue and retry using the same command as before. However, for > blk-mq, scsi_mq_requeue_cmd is employed here which will unprepare > the request. To align with the semantics of __scsi_queue_insert, > use blk_mq_requeue_request with kick_requeue_list == true and put > the reference of scsi_device. > > Cc: Christoph Hellwig > Signed-off-by: Jianchao Wang > Reviewed-by: Bart Van Assche > --- > Changelog: > V3 -> V4: > - modify the comment and make it more clearly > > V2 -> V3: > - add comment to explain why we need a put_device in > __scsi_queue_insert > - add reviewed-by > > V1 -> V2: > - add put_device on scsi_device->sdev_gendev > drivers/scsi/scsi_lib.c | 14 +++++++++++++- > 1 file changed, 13 insertions(+), 1 deletion(-) > > diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c > index a86df9c..6ce33f6 100644 > --- a/drivers/scsi/scsi_lib.c > +++ b/drivers/scsi/scsi_lib.c > @@ -191,7 +191,19 @@ static void __scsi_queue_insert(struct scsi_cmnd *cmd, int reason, bool unbusy) > */ > cmd->result = 0; > if (q->mq_ops) { > - scsi_mq_requeue_cmd(cmd); > + /* > + * Before a SCSI command is dispatched, > + * get_device(&sdev->sdev_gendev) is called and the host, > + * target and device busy counters are increased. Since > + * requeuing a request causes these actions to be repeated and > + * since scsi_device_unbusy() has already been called, > + * put_device(&device->sdev_gendev) must still be called. Call > + * put_device() after blk_mq_requeue_request() to avoid that > + * removal of the SCSI device can start before requeueing has > + * happened. > + */ > + blk_mq_requeue_request(cmd->request, true); > + put_device(&device->sdev_gendev); > return; > } > spin_lock_irqsave(q->queue_lock, flags); >