From patchwork Sat Nov 30 02:02:24 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Yu Kuai X-Patchwork-Id: 11267813 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 688F4195A for ; Sat, 30 Nov 2019 01:41:33 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 45733215E5 for ; Sat, 30 Nov 2019 01:41:33 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727289AbfK3BlS (ORCPT ); Fri, 29 Nov 2019 20:41:18 -0500 Received: from szxga06-in.huawei.com ([45.249.212.32]:39606 "EHLO huawei.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1727227AbfK3BlR (ORCPT ); Fri, 29 Nov 2019 20:41:17 -0500 Received: from DGGEMS414-HUB.china.huawei.com (unknown [172.30.72.58]) by Forcepoint Email with ESMTP id 5E6CC6908ADF057AE9F2; Sat, 30 Nov 2019 09:41:15 +0800 (CST) Received: from huawei.com (10.175.124.28) by DGGEMS414-HUB.china.huawei.com (10.3.19.214) with Microsoft SMTP Server id 14.3.439.0; Sat, 30 Nov 2019 09:41:08 +0800 From: yu kuai To: , , , , , , , , CC: , , , , , , Subject: [PATCH 2/3] fs/libfs.c: use 'spin_lock_nested' when taking 'd_lock' for dentry in simple_empty Date: Sat, 30 Nov 2019 10:02:24 +0800 Message-ID: <20191130020225.20239-3-yukuai3@huawei.com> X-Mailer: git-send-email 2.17.2 In-Reply-To: <20191130020225.20239-1-yukuai3@huawei.com> References: <20191130020225.20239-1-yukuai3@huawei.com> MIME-Version: 1.0 X-Originating-IP: [10.175.124.28] X-CFilter-Loop: Reflected Sender: linux-fsdevel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org simple_emtpty currently use 'spin_lock_nested' for 'child' to avoid confusion for lockdep. However, it's not used for 'dentry'. In that case, there will be a problem if the caller called 'simple_empty' with a parent's 'd_lock' held: spin_lock(&dentry->d_parent->d_lock) call simple_empty(dentry) spin_lock(&dentry->d_lock) --> lockdep will report this spin_lock_nested(child->d_lock, spin_lock_nested) spin_unlock(child_lock) spin_unlock($dentry->d_lock) return from simple_empty spin_unlock(&dentry->d_patrent->d_lock) So, use 'DENTRY_D_LOCK_NESTED' for 'dentry' and 'DENTRY_D_LOCK_NESTED_TWICE' for child. Signed-off-by: yu kuai --- fs/libfs.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/fs/libfs.c b/fs/libfs.c index 1463b038ffc4..54a37444f7f9 100644 --- a/fs/libfs.c +++ b/fs/libfs.c @@ -336,9 +336,9 @@ int simple_empty(struct dentry *dentry) struct dentry *child; int ret = 0; - spin_lock(&dentry->d_lock); + spin_lock_nested(&dentry->d_lock, DENTRY_D_LOCK_NESTED); list_for_each_entry(child, &dentry->d_subdirs, d_child) { - spin_lock_nested(&child->d_lock, DENTRY_D_LOCK_NESTED); + spin_lock_nested(&child->d_lock, DENTRY_D_LOCK_NESTED_TWICE); if (simple_positive(child)) { spin_unlock(&child->d_lock); goto out;