From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S263246AbVFXK6W (ORCPT ); Fri, 24 Jun 2005 06:58:22 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S263252AbVFXK6V (ORCPT ); Fri, 24 Jun 2005 06:58:21 -0400 Received: from e35.co.us.ibm.com ([32.97.110.133]:9926 "EHLO e35.co.us.ibm.com") by vger.kernel.org with ESMTP id S263246AbVFXK4E (ORCPT ); Fri, 24 Jun 2005 06:56:04 -0400 Date: Fri, 24 Jun 2005 16:23:18 +0530 From: Dipankar Sarma To: Andrew Morton Cc: linux-kernel@vger.kernel.org Subject: Re: [PATCH 2/4] files: fix expand_files return code Message-ID: <20050624105318.GD4804@in.ibm.com> Reply-To: dipankar@in.ibm.com References: <20050624105011.GB4804@in.ibm.com> <20050624105209.GC4804@in.ibm.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20050624105209.GC4804@in.ibm.com> User-Agent: Mutt/1.4.1i Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org If expand_fdtable() sees that someone else expanded the fdtable while it dropped the lock, it can return 0 which in turn can be returned by expand_files() even though there has been an expansion of the fdtable since expand_files() was originally called. This could lead to locate_fd() not repeating the fd search and returning a bogus fd. This patch fixes this problem. Signed-off-by: Dipankar Sarma --- fs/file.c | 15 +++++++-------- 1 files changed, 7 insertions(+), 8 deletions(-) diff -puN fs/file.c~fix-expand-files fs/file.c --- linux-2.6.12-mm1-fix/fs/file.c~fix-expand-files 2005-06-25 16:42:18.000000000 +0530 +++ linux-2.6.12-mm1-fix-dipankar/fs/file.c 2005-06-25 16:42:18.000000000 +0530 @@ -304,13 +304,14 @@ out: /* * Expands the file descriptor table - it will allocate a new fdtable and * both fd array and fdset. It is expected to be called with the - * files_lock held. + * files_lock held. It returns 1 if fdtable expanded or -errno if + * expansion failed. */ static int expand_fdtable(struct files_struct *files, int nr) __releases(files->file_lock) __acquires(files->file_lock) { - int error = 0; + int error = 1; struct fdtable *fdt; struct fdtable *nfdt = NULL; @@ -350,7 +351,7 @@ out: */ int expand_files(struct files_struct *files, int nr) { - int err, expand = 0; + int err; struct fdtable *fdt; fdt = files_fdtable(files); @@ -360,11 +361,9 @@ int expand_files(struct files_struct *fi err = -EMFILE; goto out; } - expand = 1; - if ((err = expand_fdtable(files, nr))) - goto out; - } - err = expand; + err = expand_fdtable(files, nr); + } else + err = 0; out: return err; } _