From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752852AbYIJS6y (ORCPT ); Wed, 10 Sep 2008 14:58:54 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751377AbYIJS6p (ORCPT ); Wed, 10 Sep 2008 14:58:45 -0400 Received: from jalapeno.cc.columbia.edu ([128.59.29.5]:49470 "EHLO jalapeno.cc.columbia.edu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751298AbYIJS6p (ORCPT ); Wed, 10 Sep 2008 14:58:45 -0400 Message-ID: <48C8182F.5090008@cs.columbia.edu> Date: Wed, 10 Sep 2008 14:55:43 -0400 From: Oren Laadan Organization: Columbia University User-Agent: Thunderbird 2.0.0.16 (X11/20080724) MIME-Version: 1.0 To: Dave Hansen CC: containers@lists.linux-foundation.org, jeremy@goop.org, arnd@arndb.de, linux-kernel@vger.kernel.org Subject: Re: [RFC v4][PATCH 9/9] File descriprtors (restore) References: <1220946154-15174-1-git-send-email-orenl@cs.columbia.edu> <1220946154-15174-10-git-send-email-orenl@cs.columbia.edu> <1220977581.23386.216.camel@nimitz> <48C727B6.9000700@cs.columbia.edu> <1221062969.6781.5.camel@nimitz> In-Reply-To: <1221062969.6781.5.camel@nimitz> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit X-No-Spam-Score: Local Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Dave Hansen wrote: > On Tue, 2008-09-09 at 21:49 -0400, Oren Laadan wrote: >> Dave Hansen wrote: >>> On Tue, 2008-09-09 at 03:42 -0400, Oren Laadan wrote: >>>> +static int cr_close_all_fds(struct files_struct *files) >>>> +{ >>>> + int *fdtable; >>>> + int n; >>>> + >>>> + do { >>>> + n = cr_scan_fds(files, &fdtable); >>>> + if (n < 0) >>>> + return n; >>>> + while (n--) >>>> + sys_close(fdtable[n]); >>>> + kfree(fdtable); >>>> + } while (n != -1); >>>> + >>>> + return 0; >>>> +} >>> This needs to use an ERR_PTR(). It will save using the double-pointer. >> I suppose you refer to the call to cr_scan_fds(): either 'fdtable' >> or 'n' will have to pass-by-reference. Is it that you prefer it to be >> fdtable = cr_scan_fds(files, &n); >> ? > > I was misreading the use of 'n'. Can you really not use close_files() > for this operation? You'd need to add some locking around it, but I > think it does what you need here. I thought about that. However, close_files() assumes that the files_struct will be discarded thereafter, so it does not reset ->fd_open->fd_bits[] bits, does not adjust ->next_fd field, and does not use rcu_assign_pointer(). And then, even if we adjust, we'll have to watch future differences between sys_close() and close_files(), so using sys_close() is more future-proof. Besides, cr_scan_fds() is used by the checkpoint logic already, so it's easy to reuse for restart as well. Oren.