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=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 1616FCA9EAB for ; Fri, 18 Oct 2019 22:17:01 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id D2B9720679 for ; Fri, 18 Oct 2019 22:17:00 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1571437020; bh=7anIju3GzbRm18JdCkJS7Bg+9lKUk0OQ3BDxqqY5L24=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=Xl9ozI/f5FXJj3QYFPP+i/SPkJxGfwwQAUI8kY/I11Oj3tQpjzjDfklqSG63b8B1O TMlLPl5maclRHYpPNrhXrEjqD75GxtZQOISs59Q9Ijws7jj12Rh7CjClEkiaLOjb19 d/UZoca7lMBtidi6zp7KaSLGg+MChQHIN75YWUuo= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2387450AbfJRWH6 (ORCPT ); Fri, 18 Oct 2019 18:07:58 -0400 Received: from mail.kernel.org ([198.145.29.99]:40212 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1733241AbfJRWHs (ORCPT ); Fri, 18 Oct 2019 18:07:48 -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 D95CE222D1; Fri, 18 Oct 2019 22:07:46 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1571436467; bh=7anIju3GzbRm18JdCkJS7Bg+9lKUk0OQ3BDxqqY5L24=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=Bu2c6ZrzQNAgR6iUWOCpixSD+B04Rsv6aarfMBTMe8KLw9q7Wx2uK/MQyVraFke2I UH8guMLvzeUnMb6sox1lEzGI8oKUoucXPhGlKZnPbwVMg7ikEz2U9Bvk6HlqPLRrOf G9ys6yR/f1qX27nunWHK5WhWXcguntLWaS2eoS90= 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 4.19 097/100] nbd: fix possible sysfs duplicate warning Date: Fri, 18 Oct 2019 18:05:22 -0400 Message-Id: <20191018220525.9042-97-sashal@kernel.org> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20191018220525.9042-1-sashal@kernel.org> References: <20191018220525.9042-1-sashal@kernel.org> MIME-Version: 1.0 X-stable: review X-Patchwork-Hint: Ignore Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@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 bc2fa4e85f0ca..d445195945618 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