Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1030385AbWBHRal (ORCPT ); Wed, 8 Feb 2006 12:30:41 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1030382AbWBHRal (ORCPT ); Wed, 8 Feb 2006 12:30:41 -0500 Received: from ebiederm.dsl.xmission.com ([166.70.28.69]:62621 "EHLO ebiederm.dsl.xmission.com") by vger.kernel.org with ESMTP id S1030385AbWBHRak (ORCPT ); Wed, 8 Feb 2006 12:30:40 -0500 To: Oleg Nesterov Cc: Andrew Morton , linux-kernel@vger.kernel.org Subject: Re: [PATCH] fork: Allow init to become a session leader. References: <43EA386B.D1A20AEB@tv-sign.ru> From: ebiederm@xmission.com (Eric W. Biederman) Date: Wed, 08 Feb 2006 10:29:55 -0700 In-Reply-To: <43EA386B.D1A20AEB@tv-sign.ru> (Oleg Nesterov's message of "Wed, 08 Feb 2006 21:28:59 +0300") Message-ID: User-Agent: Gnus/5.1007 (Gnus v5.10.7) Emacs/21.4 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2020 Lines: 46 Oleg Nesterov writes: > "Eric W. Biederman" wrote: >> >> With the bug fixes from killing session == 0 and pgrp == 0 we >> have essentially made pid == 1 a session leader. However reading >> through the code I can see nothing, that sets the session->leader >> flag. In fact we actively clear it in all cases during clone. >> And setsid will fail to set it because the session == 1 and >> process group == 1 already exist. >> >> So this patch forces the session leader flag and for good measure >> the pgrp, session and tty of init as well. >> >> --- a/kernel/fork.c >> +++ b/kernel/fork.c >> @@ -1179,9 +1179,16 @@ static task_t *copy_process(unsigned lon >> attach_pid(p, PIDTYPE_PID, p->pid); >> attach_pid(p, PIDTYPE_TGID, p->tgid); >> if (thread_group_leader(p)) { >> - p->signal->tty = current->signal->tty; >> - p->signal->pgrp = process_group(current); >> - p->signal->session = current->signal->session; >> + if (unlikely(p->pid == 1)) { >> + p->signal->tty = NULL; >> + p->signal->leader = 1; >> + p->signal->pgrp = 1; >> + p->signal->session = 1; > > Isn't it enough to just set current->signal->leader = 1 > in init/main.c:init() ? This process was already forked > with (1,1) special pids and ->tty == NULL. At the moment yes. Being explicit can help readability. This allows us the opportunity to leave the unhashed idle task as (0,0) and more interesting to me, if we ever fork another process with pid == 1 in a different process id namespace we do need to do all of this. Eric - 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/