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=-10.1 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=unavailable 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 E7AE0CA9EA9 for ; Fri, 18 Oct 2019 22:14:52 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id B2F3121852 for ; Fri, 18 Oct 2019 22:14:52 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1571436892; bh=dcVigU6fDMmZoextzHaCniTrTK6eBi3KgAmY8viInsA=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=kia7IU2Oa1xC6V3paFj0XnePFJRzJN8r1MN9ymB4LazWnNXGdYJDrZJVsienXeoa6 imL70bJ0TihEGyN9Prk3+ebTh3hiEy3C5M6BOi48wTb0yLAOl6UE0AWctPB9UB++b7 Q1DAJjisGxWJwL5ovW2rgWy+LsF3JfJyHTz/dcr0= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2392362AbfJRWOs (ORCPT ); Fri, 18 Oct 2019 18:14:48 -0400 Received: from mail.kernel.org ([198.145.29.99]:41954 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2388719AbfJRWJQ (ORCPT ); Fri, 18 Oct 2019 18:09:16 -0400 Received: from sasha-vm.mshome.net (c-73-47-72-35.hsd1.nh.comcast.net [73.47.72.35]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 0BEE72246A; Fri, 18 Oct 2019 22:09:14 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1571436556; bh=dcVigU6fDMmZoextzHaCniTrTK6eBi3KgAmY8viInsA=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=z5TSf3fEqy8DarWcxh48UXXVG1XUS5/ElpNR7Xh7idaj9R7si1WGh9hHD1ndkK0Ck TJhHeMOi6Xn/oxp7QJlb8wt3tKj98969aYlo33RxEdstMKCRwy6AjMZpm4Oo75no9b z/L1nKHCrGd7T5VJ+a7cSjCtd1NCoABQ+4XgqUvE= From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Xiubo Li , Mike Christie , Josef Bacik , Jens Axboe , Sasha Levin , linux-block@vger.kernel.org, nbd@other.debian.org Subject: [PATCH AUTOSEL 4.14 53/56] nbd: fix possible sysfs duplicate warning Date: Fri, 18 Oct 2019 18:07:50 -0400 Message-Id: <20191018220753.10002-53-sashal@kernel.org> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20191018220753.10002-1-sashal@kernel.org> References: <20191018220753.10002-1-sashal@kernel.org> MIME-Version: 1.0 X-stable: review X-Patchwork-Hint: Ignore Content-Transfer-Encoding: 8bit Sender: stable-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Xiubo Li [ Upstream commit 862488105b84ca744b3d8ff131e0fcfe10644be1 ] 1. nbd_put takes the mutex and drops nbd->ref to 0. It then does idr_remove and drops the mutex. 2. nbd_genl_connect takes the mutex. idr_find/idr_for_each fails to find an existing device, so it does nbd_dev_add. 3. just before the nbd_put could call nbd_dev_remove or not finished totally, but if nbd_dev_add try to add_disk, we can hit: debugfs: Directory 'nbd1' with parent 'block' already present! This patch will make sure all the disk add/remove stuff are done by holding the nbd_index_mutex lock. Reported-by: Mike Christie Reviewed-by: Josef Bacik Signed-off-by: Xiubo Li Signed-off-by: Jens Axboe Signed-off-by: Sasha Levin --- drivers/block/nbd.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/block/nbd.c b/drivers/block/nbd.c index a234600849558..3e45004407963 100644 --- a/drivers/block/nbd.c +++ b/drivers/block/nbd.c @@ -228,8 +228,8 @@ static void nbd_put(struct nbd_device *nbd) if (refcount_dec_and_mutex_lock(&nbd->refs, &nbd_index_mutex)) { idr_remove(&nbd_index_idr, nbd->index); - mutex_unlock(&nbd_index_mutex); nbd_dev_remove(nbd); + mutex_unlock(&nbd_index_mutex); } } -- 2.20.1