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=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_PASS, T_DKIMWL_WL_HIGH 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 8761AC4321D for ; Mon, 20 Aug 2018 01:29:14 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 2740620936 for ; Mon, 20 Aug 2018 01:29:14 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=oracle.com header.i=@oracle.com header.b="ixK593oM" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 2740620936 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=oracle.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726043AbeHTEmo (ORCPT ); Mon, 20 Aug 2018 00:42:44 -0400 Received: from aserp2120.oracle.com ([141.146.126.78]:53422 "EHLO aserp2120.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725944AbeHTEmo (ORCPT ); Mon, 20 Aug 2018 00:42:44 -0400 Received: from pps.filterd (aserp2120.oracle.com [127.0.0.1]) by aserp2120.oracle.com (8.16.0.22/8.16.0.22) with SMTP id w7K1T6EQ092918; Mon, 20 Aug 2018 01:29:06 GMT DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=oracle.com; h=subject : to : cc : references : from : message-id : date : mime-version : in-reply-to : content-type : content-transfer-encoding; s=corp-2018-07-02; bh=E4RSNjI3tGlH9ZeEygUpgZa+HQD33hPQwF2yrwOKreU=; b=ixK593oMgvTz3GFNm/3XNqTe2fjNFYQwqNbYwRYmLunwUdJN6px2dBzyZ2SJxaUqbVGI NO/EYW8hzG25XoZf+1YdGwDP+KRX2U9fCcXeXQhHNTqMRAeO3MTH49p+uOMDC+8kOO9L Hlv7SqvFh9mW5YsyxOuDjPvzpnl1LnO6SjF8gWfrKTq3jk8I5Uzi+NVctrqjlEQqX47W NgLpjM4455wKvNmVZA0ibWVf1xy5DWVb5f+3BMl+0oskEoAfBl8M0+648J/bTubbdHsj jU3ffphP0Npfkck5+pj++LPFG87uHWuL8i5Oi8x3mx3OJwwRqECBKV2H6BHX65iKejfq hQ== Received: from aserv0022.oracle.com (aserv0022.oracle.com [141.146.126.234]) by aserp2120.oracle.com with ESMTP id 2kxbdpknws-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Mon, 20 Aug 2018 01:29:06 +0000 Received: from aserv0122.oracle.com (aserv0122.oracle.com [141.146.126.236]) by aserv0022.oracle.com (8.14.4/8.14.4) with ESMTP id w7K1T5h1014083 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Mon, 20 Aug 2018 01:29:05 GMT Received: from abhmp0008.oracle.com (abhmp0008.oracle.com [141.146.116.14]) by aserv0122.oracle.com (8.14.4/8.14.4) with ESMTP id w7K1T3X7008289; Mon, 20 Aug 2018 01:29:04 GMT Received: from [10.182.70.180] (/10.182.70.180) by default (Oracle Beehive Gateway v4.0) with ESMTP ; Sun, 19 Aug 2018 18:29:03 -0700 Subject: Re: [PATCH V2 1/2] blk-mq: init hctx sched after update ctx and hctx mapping To: Ming Lei Cc: Jens Axboe , Bart Van Assche , Keith Busch , linux-block , Linux Kernel Mailing List References: <1534478043-7170-1-git-send-email-jianchao.w.wang@oracle.com> <1534478043-7170-2-git-send-email-jianchao.w.wang@oracle.com> From: "jianchao.wang" Message-ID: <96657784-dd95-6ea9-3ffd-25737c534075@oracle.com> Date: Mon, 20 Aug 2018 09:29:36 +0800 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.9.1 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit X-Proofpoint-Virus-Version: vendor=nai engine=5900 definitions=8990 signatures=668707 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 suspectscore=0 malwarescore=0 phishscore=0 bulkscore=0 spamscore=0 mlxscore=0 mlxlogscore=813 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1807170000 definitions=main-1808200014 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Ming On 08/17/2018 05:33 PM, Ming Lei wrote: >> + /* >> + * elevator_release will put it. >> + */ >> + __module_get(q->elv_type->elevator_owner); > I understand what elevator_release() frees is the 'ref-counter' got in > elevator_get(), but who will be the counter-pair of the above __module_get()? Sorry for my bad description. The code path is: elevator_release -> elevator_put(e->type) -> module_put(e->elevator_owner) In normal elevator switch path, elevator_get will hold a reference counter of the elevator_owner. In this patch set, the elevator_type is saved directly. To prevent the io scheduler module is removed, we need to hold a reference of the module. Thanks Jianchao