From patchwork Wed Aug 18 06:24:55 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Christoph Hellwig X-Patchwork-Id: 12443411 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=-16.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT 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 D52F0C4338F for ; Wed, 18 Aug 2021 06:36:53 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id BECEA60F11 for ; Wed, 18 Aug 2021 06:36:53 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S238116AbhHRGhY (ORCPT ); Wed, 18 Aug 2021 02:37:24 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:51454 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S237981AbhHRGhX (ORCPT ); Wed, 18 Aug 2021 02:37:23 -0400 Received: from casper.infradead.org (casper.infradead.org [IPv6:2001:8b0:10b:1236::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 80F4BC061764 for ; Tue, 17 Aug 2021 23:36:49 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.20170209; h=Content-Transfer-Encoding:MIME-Version: References:In-Reply-To:Message-Id:Date:Subject:Cc:To:From:Sender:Reply-To: Content-Type:Content-ID:Content-Description; bh=FXmTMF6Ajh70k0duCWm0jFiKANkPK/mgbhge+anQB8U=; b=AyDStgbo3Wg90sV+CuhwoX0jeQ Dj7QnuifN+rI6qt9MLD2vYF/shSBkMYwnE0CATzfq5Vw+9GjFJyYme1gr3zpVMqZtM5MJOQJxtGix 45s01yGVl1OZ0WnBykc29PWZTInH5hjf5UCHdky/A3UysN2sHcAujxatI62TbsnWUg7zlqJCncWmt yrk5MHZyxXXcSQpQwS8zGy7cTJk8LoV2t9Skm00TzgjobOfESB/NeRzYE+afMuZ1t6QpXPMDZnMQU 4KcePiMj57DKNg/w5dAp7IUFoLf0sY+zBOEji0p5z3m0969E8WdkqolnBBbAKBtTC3CewUMmjUJcO VAuLWs0g==; Received: from 213-225-12-39.nat.highway.a1.net ([213.225.12.39] helo=localhost) by casper.infradead.org with esmtpsa (Exim 4.94.2 #2 (Red Hat Linux)) id 1mGF9p-003Rmb-10; Wed, 18 Aug 2021 06:34:46 +0000 From: Christoph Hellwig To: Jens Axboe Cc: Hillf Danton , Tetsuo Handa , Pavel Tatashin , "Reviewed-by : Tyler Hicks" , linux-block@vger.kernel.org Subject: [PATCH 7/7] loop: avoid holding loop_ctl_mutex over add_disk Date: Wed, 18 Aug 2021 08:24:55 +0200 Message-Id: <20210818062455.211065-8-hch@lst.de> X-Mailer: git-send-email 2.30.2 In-Reply-To: <20210818062455.211065-1-hch@lst.de> References: <20210818062455.211065-1-hch@lst.de> MIME-Version: 1.0 X-SRS-Rewrite: SMTP reverse-path rewritten from by casper.infradead.org. See http://www.infradead.org/rpr.html Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org To avoid complex lock ordering issues loop_ctl_mutex should not be held over add_disk. Add a new Lo_new state for a loop device that has just been created but which is not live yet. Reported-by: Tetsuo Handa Signed-off-by: Christoph Hellwig --- drivers/block/loop.c | 16 ++++++++++++---- drivers/block/loop.h | 1 + 2 files changed, 13 insertions(+), 4 deletions(-) diff --git a/drivers/block/loop.c b/drivers/block/loop.c index 043673bda8b3..80f462edc39f 100644 --- a/drivers/block/loop.c +++ b/drivers/block/loop.c @@ -2329,7 +2329,7 @@ static int loop_add(int i) lo = kzalloc(sizeof(*lo), GFP_KERNEL); if (!lo) goto out; - lo->lo_state = Lo_unbound; + lo->lo_state = Lo_new; err = mutex_lock_killable(&loop_ctl_mutex); if (err) @@ -2343,8 +2343,9 @@ static int loop_add(int i) } else { err = idr_alloc(&loop_index_idr, lo, 0, 0, GFP_KERNEL); } + mutex_unlock(&loop_ctl_mutex); if (err < 0) - goto out_unlock; + goto out_free_dev; i = err; err = -ENOMEM; @@ -2414,15 +2415,22 @@ static int loop_add(int i) disk->event_flags = DISK_EVENT_FLAG_UEVENT; sprintf(disk->disk_name, "loop%d", i); add_disk(disk); + + err = mutex_lock_killable(&loop_ctl_mutex); + if (err) + goto out_del_gendisk; + lo->lo_state = Lo_unbound; mutex_unlock(&loop_ctl_mutex); + return i; +out_del_gendisk: + del_gendisk(lo->lo_disk); + blk_cleanup_disk(lo->lo_disk); out_cleanup_tags: blk_mq_free_tag_set(&lo->tag_set); out_free_idr: idr_remove(&loop_index_idr, i); -out_unlock: - mutex_unlock(&loop_ctl_mutex); out_free_dev: kfree(lo); out: diff --git a/drivers/block/loop.h b/drivers/block/loop.h index d14ce6bdc014..608a20c23c64 100644 --- a/drivers/block/loop.h +++ b/drivers/block/loop.h @@ -24,6 +24,7 @@ enum { Lo_bound, Lo_rundown, Lo_deleting, + Lo_new, }; struct loop_func_table;