Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754429AbZJESbb (ORCPT ); Mon, 5 Oct 2009 14:31:31 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1754169AbZJESbb (ORCPT ); Mon, 5 Oct 2009 14:31:31 -0400 Received: from mx1.redhat.com ([209.132.183.28]:27811 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752406AbZJESba (ORCPT ); Mon, 5 Oct 2009 14:31:30 -0400 Date: Mon, 5 Oct 2009 20:25:36 +0200 From: Oleg Nesterov To: Sukadev Bhattiprolu Cc: Andrew Morton , Daniel Lezcano , Sukadev Bhattiprolu , Linux Containers , roland@redhat.com, linux-kernel@vger.kernel.org Subject: Re: [PATCH 2/4] signals: send_signal: use si_fromuser() to detect from_ancestor_ns Message-ID: <20091005182536.GA943@redhat.com> References: <4AC608BE.9020805@fr.ibm.com> <20091003171029.GA30442@us.ibm.com> <20091004021844.GA21006@redhat.com> <20091004021954.GC21006@redhat.com> <20091005181255.GE30442@us.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20091005181255.GE30442@us.ibm.com> User-Agent: Mutt/1.5.18 (2008-05-17) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1864 Lines: 51 On 10/05, Sukadev Bhattiprolu wrote: > > Oleg Nesterov [oleg@redhat.com] wrote: > | > | --- TTT_32/kernel/signal.c~FU_2_SEND_SIGNAL 2009-10-04 02:21:55.000000000 +0200 > | +++ TTT_32/kernel/signal.c 2009-10-04 03:09:44.000000000 +0200 > | @@ -928,9 +928,8 @@ static int send_signal(int sig, struct s > | int from_ancestor_ns = 0; > | > | #ifdef CONFIG_PID_NS > | - if (!is_si_special(info) && SI_FROMUSER(info) && > | - task_pid_nr_ns(current, task_active_pid_ns(t)) <= 0) > | - from_ancestor_ns = 1; > | + from_ancestor_ns = si_fromuser(info) && > | + !task_pid_nr_ns(current, task_active_pid_ns(t)); > > Makes sense. And we had mentioned earlier that container-init is immune > to suicide but should we add a check for 'current == t' above to cover the > > send_sig(SIGKILL, current, 0); > > in load_aout_binary() and friends > > from_ancestor_ns = si_fromuser(info) && (current == t || > !task_pid_nr_ns(current, task_active_pid_ns(t))); I don't think so. First of all, this is just ugly. If we need this check we should change the callers, not send_signal(). But more importantly, I disagree with "container-init is immune to suicide" above. This is another issue I was going to discuss later, lets do this now. When load_elf_binary() does send_sig(SIGKILL, current) init must die, because we have no option. Exec failed, but we can't return to user-space with the error code, it is too late. So, imho this patch also fixes this case by accident, but I think it would be better to change load_aout_binary/etc to use force_sig_info() to make the code more explicit. What do you think? Oleg. -- 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/