From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S272281AbTHBIvD (ORCPT ); Sat, 2 Aug 2003 04:51:03 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S272325AbTHBIvD (ORCPT ); Sat, 2 Aug 2003 04:51:03 -0400 Received: from adsl-206-170-148-147.dsl.snfc21.pacbell.net ([206.170.148.147]:47624 "EHLO gw.goop.org") by vger.kernel.org with ESMTP id S272281AbTHBIvA (ORCPT ); Sat, 2 Aug 2003 04:51:00 -0400 Subject: Re: [PATCH] bug in setpgid()? process groups and thread groups From: Jeremy Fitzhardinge To: Ulrich Drepper Cc: Linux Kernel List , Roland McGrath , Andrew Morton In-Reply-To: <3F2B7435.7070101@redhat.com> References: <1059811048.18516.43.camel@ixodes.goop.org> <3F2B7435.7070101@redhat.com> Content-Type: text/plain Message-Id: <1059814257.18860.38.camel@ixodes.goop.org> Mime-Version: 1.0 X-Mailer: Ximian Evolution 1.4.3 Date: 02 Aug 2003 01:50:58 -0700 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Sat, 2003-08-02 at 01:20, Ulrich Drepper wrote: > Your approach with iterating over the threads is not acceptable (at > least to me). I've noticed that postings with patches get paid a lot more attention to those without. It was just the patch I used to prove to myself what the problem is. > It is racy (concurrent runs are not synchronized) Erm, it's protected by tasklist_lock, so that isn't a problem. > and has > a non-constant time. We've sketched out already a mechanism which > solves to problem. Basically, most of the time the value from the > thread group leader is used (just follow the pointer). Then setting the > value is an atomic operation an constant. I was considering that, but it needs changes all over the place where people look at current->pgrp. This way makes for a clearer patch. J