Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754117AbZJETtO (ORCPT ); Mon, 5 Oct 2009 15:49:14 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753756AbZJETtN (ORCPT ); Mon, 5 Oct 2009 15:49:13 -0400 Received: from mx1.redhat.com ([209.132.183.28]:12299 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753589AbZJETtM (ORCPT ); Mon, 5 Oct 2009 15:49:12 -0400 Date: Mon, 5 Oct 2009 21:44:15 +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: <20091005194415.GA4560@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> <20091005182536.GA943@redhat.com> <20091005193738.GF30442@us.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20091005193738.GF30442@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: 2429 Lines: 68 On 10/05, Sukadev Bhattiprolu wrote: > > Oleg Nesterov [oleg@redhat.com] wrote: > | 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(). > > Well, all I am saying is that the check > > !task_pid_nr_ns(current, task_active_pid_ns(t))) > > excludes container-init sending signal to itself - task_pid_nr_ns() above > would return 1 for container-init and 'from_ancestor_ns' would be 0. Ah, I misunderstood you, and I misread the "current == t" check above. I wrongly thought that you suggest to suppress "si_fromuser()" when the task sends a signal to itself. Sorry for confusion. > But sure, we could use force_sig_info() in caller. Yes, because this makes the code more explicit imho. And we can avoid the further complicatiions in send_signal() path. > | So, imho this patch also fixes this case by accident, > > This part I am not sure. But as mentioned above, from_ancestor_ns is 0 > and the SIGKILL will not queued right ? Yes, you are right, see above. I meant, it fixes the from-user logic, not from_ancestor_ns logic. 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/