From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-1.1 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_PASS,UNPARSEABLE_RELAY autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id F1A18C10F0E for ; Sat, 13 Apr 2019 00:04:59 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id B78F7218C3 for ; Sat, 13 Apr 2019 00:04:59 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=oracle.com header.i=@oracle.com header.b="zIRM5q93" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726898AbfDMAE7 (ORCPT ); Fri, 12 Apr 2019 20:04:59 -0400 Received: from aserp2130.oracle.com ([141.146.126.79]:45646 "EHLO aserp2130.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726765AbfDMAE6 (ORCPT ); Fri, 12 Apr 2019 20:04:58 -0400 Received: from pps.filterd (aserp2130.oracle.com [127.0.0.1]) by aserp2130.oracle.com (8.16.0.27/8.16.0.27) with SMTP id x3D048XT068856; Sat, 13 Apr 2019 00:04:47 GMT DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=oracle.com; h=to : cc : subject : from : references : date : in-reply-to : message-id : mime-version : content-type; s=corp-2018-07-02; bh=cgZIvkDZ77yg9SvwpZSCfx3oA3KFmAar6EesdHF3ezQ=; b=zIRM5q932BlVEB7/i0Xjb8UiWii7cq1TgWYAY/sizxwboFRMCbiTLnRgF0WWtiRX08B2 d/AbypLFeaRM5I+av0/h68zKPsGzE5dxppbdIfgEPpNIiXBv6TrVoYUPd+/umKzb8wk/ vq7SejZl/NJMmqKdp6lPiXMGn8NvL8AaKnJi65mFrd9fhNMU5Npn413UYzX9F2AiTDGO z3+vYAGbF51QDdj00CrtKNJEd++t8oWR5IW7E5bLFxZJkV/k8G8nkOj90GDCse3ZTnb1 2BfQ1TQEe3HCCX6M8myxkeDG1NgkSk0JKULBOTmvJW52KGerWOO5rxna5IFaUyw01fTg cA== Received: from aserp3030.oracle.com (aserp3030.oracle.com [141.146.126.71]) by aserp2130.oracle.com with ESMTP id 2rphmf13me-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Sat, 13 Apr 2019 00:04:47 +0000 Received: from pps.filterd (aserp3030.oracle.com [127.0.0.1]) by aserp3030.oracle.com (8.16.0.27/8.16.0.27) with SMTP id x3D03j78061908; Sat, 13 Apr 2019 00:04:47 GMT Received: from aserv0121.oracle.com (aserv0121.oracle.com [141.146.126.235]) by aserp3030.oracle.com with ESMTP id 2rt9uqddw7-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Sat, 13 Apr 2019 00:04:47 +0000 Received: from abhmp0003.oracle.com (abhmp0003.oracle.com [141.146.116.9]) by aserv0121.oracle.com (8.14.4/8.13.8) with ESMTP id x3D04hH7004121; Sat, 13 Apr 2019 00:04:44 GMT Received: from ca-mkp.ca.oracle.com (/10.159.214.123) by default (Oracle Beehive Gateway v4.0) with ESMTP ; Fri, 12 Apr 2019 17:04:43 -0700 To: Ming Lei Cc: Jens Axboe , linux-block@vger.kernel.org, Dongli Zhang , James Smart , Bart Van Assche , linux-scsi@vger.kernel.org, "Martin K . Petersen" , Christoph Hellwig , "James E . J . Bottomley" , jianchao wang Subject: Re: [PATCH V5 9/9] SCSI: don't hold device refcount in IO path From: "Martin K. Petersen" Organization: Oracle Corporation References: <20190412033032.10418-1-ming.lei@redhat.com> <20190412033032.10418-10-ming.lei@redhat.com> Date: Fri, 12 Apr 2019 20:04:40 -0400 In-Reply-To: <20190412033032.10418-10-ming.lei@redhat.com> (Ming Lei's message of "Fri, 12 Apr 2019 11:30:32 +0800") Message-ID: User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/26.1.92 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain X-Proofpoint-Virus-Version: vendor=nai engine=5900 definitions=9225 signatures=668685 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 suspectscore=0 malwarescore=0 phishscore=0 bulkscore=0 spamscore=0 mlxscore=0 mlxlogscore=731 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1810050000 definitions=main-1904120158 X-Proofpoint-Virus-Version: vendor=nai engine=5900 definitions=9225 signatures=668685 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 priorityscore=1501 malwarescore=0 suspectscore=0 phishscore=0 bulkscore=0 spamscore=0 clxscore=1015 lowpriorityscore=0 mlxscore=0 impostorscore=0 mlxlogscore=754 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1810050000 definitions=main-1904120159 Sender: linux-block-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org Ming, > scsi_device's refcount is always grabbed in IO path. > > Turns out it isn't necessary, because blk_queue_cleanup() will > drain any in-flight IOs, then cancel timeout/requeue work, and > SCSI's requeue_work is canceled too in __scsi_remove_device(). > > Also scsi_device won't go away until blk_cleanup_queue() is done. > > So don't hold the refcount in IO path, especially the refcount isn't > required in IO path since blk_queue_enter() / blk_queue_exit() > is introduced in the legacy block layer. This all looks good to me. I assume it will go through Jens' tree? Acked-by: Martin K. Petersen -- Martin K. Petersen Oracle Linux Engineering