From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933528Ab1ESQXY (ORCPT ); Thu, 19 May 2011 12:23:24 -0400 Received: from mx1.redhat.com ([209.132.183.28]:41993 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932238Ab1ESQXY (ORCPT ); Thu, 19 May 2011 12:23:24 -0400 Date: Thu, 19 May 2011 18:21:29 +0200 From: Oleg Nesterov To: Tejun Heo Cc: jan.kratochvil@redhat.com, vda.linux@googlemail.com, linux-kernel@vger.kernel.org, torvalds@linux-foundation.org, akpm@linux-foundation.org, indan@nul.nu, bdonlan@gmail.com Subject: Re: [PATCH 04/10] ptrace: implement PTRACE_INTERRUPT Message-ID: <20110519162129.GC17265@redhat.com> References: <1305569849-10448-1-git-send-email-tj@kernel.org> <1305569849-10448-5-git-send-email-tj@kernel.org> <20110518183815.GA1064@redhat.com> <20110519120723.GE627@htj.dyndns.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20110519120723.GE627@htj.dyndns.org> 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 On 05/19, Tejun Heo wrote: > > Hello, > > On Wed, May 18, 2011 at 08:38:15PM +0200, Oleg Nesterov wrote: > > On 05/16, Tejun Heo wrote: > > > > > > + case PTRACE_INTERRUPT: > > > + /* > > > + * Stop tracee without any side-effect on signal or job > > > + * control. At least one trap is guaranteed to happen > > > + * after this request. If @child is already trapped, the > > > + * current trap is not disturbed and another trap will > > > + * happen after the current trap is ended with PTRACE_CONT. > > > + * > > > + * The actual trap might not be PTRACE_EVENT_STOP trap but > > > + * the pending condition is cleared regardless. > > > + */ > > > + if (likely(child->ptrace & PT_SEIZED) && > > > + lock_task_sighand(child, &flags)) { > > > + child->jobctl |= JOBCTL_TRAP_STOP; > > > > The same race with do_signal_stop() afaics. > > I didn't understand that one, Yeah, I was wrong, see the previous email. Oleg.