From patchwork Tue Jun 19 07:00:37 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "jianchao.wang" X-Patchwork-Id: 10473371 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork.web.codeaurora.org (Postfix) with ESMTP id 1D8B9603B5 for ; Tue, 19 Jun 2018 06:59:31 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 1B64A28A02 for ; Tue, 19 Jun 2018 06:59:31 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 1019B28A0C; Tue, 19 Jun 2018 06:59:31 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-8.0 required=2.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,MAILING_LIST_MULTI,RCVD_IN_DNSWL_HI, UNPARSEABLE_RELAY autolearn=ham version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id A2A2F28A02 for ; Tue, 19 Jun 2018 06:59:30 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S937309AbeFSG73 (ORCPT ); Tue, 19 Jun 2018 02:59:29 -0400 Received: from userp2130.oracle.com ([156.151.31.86]:48650 "EHLO userp2130.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S935908AbeFSG73 (ORCPT ); Tue, 19 Jun 2018 02:59:29 -0400 Received: from pps.filterd (userp2130.oracle.com [127.0.0.1]) by userp2130.oracle.com (8.16.0.22/8.16.0.22) with SMTP id w5J6wvrk188768; Tue, 19 Jun 2018 06:59:27 GMT DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=oracle.com; h=from : to : cc : subject : date : message-id; s=corp-2017-10-26; bh=PfFA2rBNJvD28yGuA5Ef0100Jii92KvUUKnoSUrwqYY=; b=rFZwbdLQzur42jRHL6EB1ZSevMJR2vVHjxirWiJSyEi+fjO4KUpVmJj85qDF5iFSsux4 PaHLsbl801NfmJpdWtNUELBfLEWcksqR4aitLwXEhuGmtkJUJrCcifo6IM13V7d0/fg6 e/ns8lgHzCBLn6KbRBnM9T4j4VYAgdv/UenFBc/FY6WUbauUmAVgficPQYpXib0nONsv EYAklJ2dWf76k64ZcZKj0X11XElhEJVpLEfx3wgQ4KoSNOrtgYkTOBgmTcwdArUndFrR f5o7Q2ii30jgxch09hYu4h24PhZmtdFUBSPT0AVQzWw9/OhKd0+++dnoVyoBX5Cf7JHg rQ== Received: from aserv0021.oracle.com (aserv0021.oracle.com [141.146.126.233]) by userp2130.oracle.com with ESMTP id 2jmt01etye-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Tue, 19 Jun 2018 06:59:27 +0000 Received: from aserv0121.oracle.com (aserv0121.oracle.com [141.146.126.235]) by aserv0021.oracle.com (8.14.4/8.14.4) with ESMTP id w5J6xQoI019407 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Tue, 19 Jun 2018 06:59:26 GMT Received: from abhmp0016.oracle.com (abhmp0016.oracle.com [141.146.116.22]) by aserv0121.oracle.com (8.14.4/8.13.8) with ESMTP id w5J6xQm8003770; Tue, 19 Jun 2018 06:59:26 GMT Received: from will-ThinkCentre-M910s.cn.oracle.com (/10.182.70.254) by default (Oracle Beehive Gateway v4.0) with ESMTP ; Mon, 18 Jun 2018 23:59:26 -0700 From: Jianchao Wang To: axboe@kernel.dk Cc: linux-block@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH] blk-mq: use mutex_trylock to avoid lock inversion Date: Tue, 19 Jun 2018 15:00:37 +0800 Message-Id: <1529391637-1704-1-git-send-email-jianchao.w.wang@oracle.com> X-Mailer: git-send-email 2.7.4 X-Proofpoint-Virus-Version: vendor=nai engine=5900 definitions=8928 signatures=668702 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 suspectscore=1 malwarescore=0 phishscore=0 bulkscore=0 spamscore=0 mlxscore=0 mlxlogscore=944 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1805220000 definitions=main-1806190081 Sender: linux-block-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP Currently, the kobject_del for kobjs of mq, hctx and ctx is invoked under sysfs_lock, lock inversion will come up when other one is acessing the associated sysfs file and trying to acquire the sysfs_lock. To fix it, use mutex_trylock in blk_mq_sysfs_ops and blk_mq_hw_sysfs_ops, if the lock in on contending, return -EAGAIN. Signed-off-by: Jianchao Wang --- block/blk-mq-sysfs.c | 52 ++++++++++++++++++++++++++++++++-------------------- 1 file changed, 32 insertions(+), 20 deletions(-) diff --git a/block/blk-mq-sysfs.c b/block/blk-mq-sysfs.c index aafb442..210804f 100644 --- a/block/blk-mq-sysfs.c +++ b/block/blk-mq-sysfs.c @@ -53,11 +53,14 @@ static ssize_t blk_mq_sysfs_show(struct kobject *kobj, struct attribute *attr, if (!entry->show) return -EIO; - res = -ENOENT; - mutex_lock(&q->sysfs_lock); - if (!blk_queue_dying(q)) - res = entry->show(ctx, page); - mutex_unlock(&q->sysfs_lock); + res = -EAGAIN; + if (mutex_trylock(&q->sysfs_lock)) { + if (!blk_queue_dying(q)) + res = entry->show(ctx, page); + else + res = -ENOENT; + mutex_unlock(&q->sysfs_lock); + } return res; } @@ -76,11 +79,14 @@ static ssize_t blk_mq_sysfs_store(struct kobject *kobj, struct attribute *attr, if (!entry->store) return -EIO; - res = -ENOENT; - mutex_lock(&q->sysfs_lock); - if (!blk_queue_dying(q)) - res = entry->store(ctx, page, length); - mutex_unlock(&q->sysfs_lock); + res = -EAGAIN; + if (mutex_trylock(&q->sysfs_lock)) { + if (!blk_queue_dying(q)) + res = entry->store(ctx, page, length); + else + res = -ENOENT; + mutex_unlock(&q->sysfs_lock); + } return res; } @@ -99,11 +105,14 @@ static ssize_t blk_mq_hw_sysfs_show(struct kobject *kobj, if (!entry->show) return -EIO; - res = -ENOENT; - mutex_lock(&q->sysfs_lock); - if (!blk_queue_dying(q)) - res = entry->show(hctx, page); - mutex_unlock(&q->sysfs_lock); + res = -EAGAIN; + if (mutex_trylock(&q->sysfs_lock)) { + if (!blk_queue_dying(q)) + res = entry->show(hctx, page); + else + res = -ENOENT; + mutex_unlock(&q->sysfs_lock); + } return res; } @@ -123,11 +132,14 @@ static ssize_t blk_mq_hw_sysfs_store(struct kobject *kobj, if (!entry->store) return -EIO; - res = -ENOENT; - mutex_lock(&q->sysfs_lock); - if (!blk_queue_dying(q)) - res = entry->store(hctx, page, length); - mutex_unlock(&q->sysfs_lock); + res = -EAGAIN; + if (mutex_trylock(&q->sysfs_lock)) { + if (!blk_queue_dying(q)) + res = entry->store(hctx, page, length); + else + res = -ENOENT; + mutex_unlock(&q->sysfs_lock); + } return res; }