Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752078AbWHOCHd (ORCPT ); Mon, 14 Aug 2006 22:07:33 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751534AbWHOCHd (ORCPT ); Mon, 14 Aug 2006 22:07:33 -0400 Received: from alnrmhc12.comcast.net ([206.18.177.52]:20416 "EHLO alnrmhc12.comcast.net") by vger.kernel.org with ESMTP id S1751456AbWHOCHb (ORCPT ); Mon, 14 Aug 2006 22:07:31 -0400 Subject: Re: Kernel patches enabling better POSIX AIO (Was Re: [3/4] kevent: AIO, aio_sendfile) From: Nicholas Miell To: Ulrich Drepper Cc: suparna@in.ibm.com, sebastien.dugue@bull.net, Badari Pulavarty , Zach Brown , Christoph Hellwig , Evgeniy Polyakov , lkml , David Miller , netdev , linux-aio@kvack.org, mingo@elte.hu In-Reply-To: <44E0A6F6.509@redhat.com> References: <1153982954.3887.9.camel@frecb000686> <44C8DB80.6030007@us.ibm.com> <44C9029A.4090705@oracle.com> <1154024943.29920.3.camel@dyn9047017100.beaverton.ibm.com> <44C90987.1040200@redhat.com> <1154034164.29920.22.camel@dyn9047017100.beaverton.ibm.com> <1154091500.13577.14.camel@frecb000686> <44DCDE73.9030901@redhat.com> <20060812182928.GA1989@in.ibm.com> <44DE27AB.7040507@redhat.com> <20060814070210.GA27005@in.ibm.com> <44E0A6F6.509@redhat.com> Content-Type: text/plain Date: Mon, 14 Aug 2006 19:06:56 -0700 Message-Id: <1155607616.2468.1.camel@entropy> Mime-Version: 1.0 X-Mailer: Evolution 2.6.2 (2.6.2-1.fc5.5.0.njm.1) Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1139 Lines: 28 On Mon, 2006-08-14 at 09:38 -0700, Ulrich Drepper wrote: > Suparna Bhattacharya wrote: > > Is there a (remote) possibility that the thread could have died and its > > pid got reused by a new thread in another process ? Or is there a mechanism > > that prevents such a possibility from arising (not just in NPTL library, > > but at the kernel level) ? > > The UID/GID won't help you with dying processes. What if the same user > creates a process with the same PID? That process will not expect the > notification and mustn't receive it. If you cannot detect whether the > issuing process died you have problems which cannot be solved with a > uid/gid pair. > > Eric W. Biederman sent a series of patches that introduced a struct task_ref specifically to solve this sort of problem on January 28 of this year, but I don't think it went anywhere. -- Nicholas Miell - 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/