From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id ; Thu, 11 Jan 2001 14:51:58 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id ; Thu, 11 Jan 2001 14:51:48 -0500 Received: from zeus.kernel.org ([209.10.41.242]:58579 "EHLO zeus.kernel.org") by vger.kernel.org with ESMTP id ; Thu, 11 Jan 2001 14:51:37 -0500 Date: Thu, 11 Jan 2001 19:47:53 +0000 From: "Stephen C. Tweedie" To: Alexander Viro Cc: "Stephen C. Tweedie" , Trond Myklebust , Linus Torvalds , Alan Cox , Andi Kleen , Daniel Phillips , linux-kernel@vger.kernel.org Subject: Re: Subtle MM bug Message-ID: <20010111194753.P25375@redhat.com> In-Reply-To: <20010111141330.H25375@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.2i In-Reply-To: ; from viro@math.psu.edu on Thu, Jan 11, 2001 at 02:03:48PM -0500 Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Hi, On Thu, Jan 11, 2001 at 02:03:48PM -0500, Alexander Viro wrote: > On Thu, 11 Jan 2001, Stephen C. Tweedie wrote: > > > On Thu, Jan 11, 2001 at 02:12:05PM +0100, Trond Myklebust wrote: > > > > > > What's wrong with copy-on-write style semantics? IOW, anyone who > > > wants to change the credentials needs to make a private copy of the > > > existing structure first. > > > > Because COW only solves the problem if each task is only changing its > > own, local, private copy of the credentials. Posix threads demand > > that one thread changing credentials also affects all the other > > threads immediately, and making your own local private copy won't help > > you to change the other tasks' credentials safely. > > And how is that different from the current situation? It's not, which is the point I was making: COW doesn't actually solve the pthreads problem. Far better to do it in user space. --Stephen - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org Please read the FAQ at http://www.tux.org/lkml/