From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752999AbXDKRvk (ORCPT ); Wed, 11 Apr 2007 13:51:40 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753415AbXDKRvk (ORCPT ); Wed, 11 Apr 2007 13:51:40 -0400 Received: from out4.smtp.messagingengine.com ([66.111.4.28]:58732 "EHLO out4.smtp.messagingengine.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753411AbXDKRvj (ORCPT ); Wed, 11 Apr 2007 13:51:39 -0400 X-Sasl-enc: kw3Jeur8rBz2rP66fpzz8Sqp5adYOB+jsqKIyLEpFkRW 1176313898 Subject: Re: [PATCH] autofs4: fix race in unhashed dentry code From: Ian Kent To: Jeff Mahoney Cc: Linux Kernel Mailing List , Andrew Morton In-Reply-To: <461CF939.9030104@suse.com> References: <461CF939.9030104@suse.com> Content-Type: text/plain Date: Thu, 12 Apr 2007 01:49:37 +0800 Message-Id: <1176313777.3377.21.camel@raven.themaw.net> Mime-Version: 1.0 X-Mailer: Evolution 2.8.0 (2.8.0-32.el5) Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Wed, 2007-04-11 at 11:05 -0400, Jeff Mahoney wrote: > Commit f50b6f8691cae2e0064c499dd3ef3f31142987f0 introduced a > race in autofs4 between autofs_lookup_unhashed() and > autofs_dentry_release(). > > autofs_dentry_release() ends up clearing the ->dentry and ->inode > members of autofs_info before removing it from the rehash list. The > list is protected by the rehash lock in both functions, but > since autofs_dentry_release() starts tearing the autofs_info struct > down before removing it from the list, autofs_lookup_unhashed() can > get a autofs_info with a NULL dentry. > > This patch moves the clearing of ->dentry and ->inode after the removal > from the rehash list. Oh .. excellent, I had a bug report but I just couldn't see it for looking. You've made my day. Thanks heaps Ian > > Signed-off-by: Jeff Mahoney Acked-by: Ian Kent > > --- > > fs/autofs4/root.c | 6 +++--- > 1 file changed, 3 insertions(+), 3 deletions(-) > > --- a/fs/autofs4/root.c 2007-04-11 09:41:44.000000000 -0400 > +++ b/fs/autofs4/root.c 2007-04-11 10:54:37.000000000 -0400 > @@ -470,9 +470,6 @@ void autofs4_dentry_release(struct dentr > if (inf) { > struct autofs_sb_info *sbi = autofs4_sbi(de->d_sb); > > - inf->dentry = NULL; > - inf->inode = NULL; > - > if (sbi) { > spin_lock(&sbi->rehash_lock); > if (!list_empty(&inf->rehash)) > @@ -480,6 +477,9 @@ void autofs4_dentry_release(struct dentr > spin_unlock(&sbi->rehash_lock); > } > > + inf->dentry = NULL; > + inf->inode = NULL; > + > autofs4_free_ino(inf); > } > } >