Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753259AbYLAUvg (ORCPT ); Mon, 1 Dec 2008 15:51:36 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751486AbYLAUv1 (ORCPT ); Mon, 1 Dec 2008 15:51:27 -0500 Received: from e4.ny.us.ibm.com ([32.97.182.144]:37346 "EHLO e4.ny.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751059AbYLAUv0 (ORCPT ); Mon, 1 Dec 2008 15:51:26 -0500 Subject: Re: [RFC v10][PATCH 08/13] Dump open file descriptors From: Dave Hansen To: Oren Laadan Cc: Al Viro , Andrew Morton , Linus Torvalds , containers@lists.linux-foundation.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, linux-api@vger.kernel.org, Thomas Gleixner , Serge Hallyn , Ingo Molnar , "H. Peter Anvin" In-Reply-To: <493447DD.7010102@cs.columbia.edu> References: <1227747884-14150-1-git-send-email-orenl@cs.columbia.edu> <1227747884-14150-9-git-send-email-orenl@cs.columbia.edu> <20081128101919.GO28946@ZenIV.linux.org.uk> <1228153645.2971.36.camel@nimitz> <493447DD.7010102@cs.columbia.edu> Content-Type: text/plain Date: Mon, 01 Dec 2008 12:51:19 -0800 Message-Id: <1228164679.2971.91.camel@nimitz> Mime-Version: 1.0 X-Mailer: Evolution 2.22.3.1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1048 Lines: 23 On Mon, 2008-12-01 at 15:23 -0500, Oren Laadan wrote: > Verifying that the size doesn't change does not ensure that the table's > contents remained the same, so we can still end up with obsolete data. With the realloc() scheme, we have virtually no guarantees about how the fdtable that we read relates to the source. All that we know is that the n'th fd was at this value at *some* time. Using the scheme that I just suggested (and you evidently originally used) at least guarantees that we have an atomic copy of the fdtable. Why is this done in two steps? It first grabs a list of fd numbers which needs to be validated, then goes back and turns those into 'struct file's which it saves off. Is there a problem with doing that fd->'struct file' conversion under the files->file_lock? -- Dave -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/