Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932215Ab1BQTlk (ORCPT ); Thu, 17 Feb 2011 14:41:40 -0500 Received: from mx1.redhat.com ([209.132.183.28]:24191 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753123Ab1BQTli (ORCPT ); Thu, 17 Feb 2011 14:41:38 -0500 Date: Thu, 17 Feb 2011 20:33:24 +0100 From: Oleg Nesterov To: Roland McGrath Cc: Jan Kratochvil , Denys Vlasenko , Tejun Heo , linux-kernel@vger.kernel.org, torvalds@linux-foundation.org, akpm@linux-foundation.org Subject: Re: [PATCH 1/1] ptrace: make sure do_wait() won't hang after PTRACE_ATTACH Message-ID: <20110217193324.GA13661@redhat.com> References: <20110204105343.GA12133@htj.dyndns.org> <20110207174821.GA1237@redhat.com> <20110209141803.GH3770@htj.dyndns.org> <201102132325.55353.vda.linux@googlemail.com> <20110214151340.GP18742@htj.dyndns.org> <20110216215157.GA6054@host1.dyn.jankratochvil.net> <20110217164906.GA5167@redhat.com> <20110217185847.5E9D31806EE@magilla.sf.frob.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20110217185847.5E9D31806EE@magilla.sf.frob.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: 1244 Lines: 35 On 02/17, Roland McGrath wrote: > > > OK... Yes, perhaps PTRACE_{DETACH,CONT}(SIGCONT) should override > > SIGNAL_STOP_STOPPED too. This makes sense, and this connects to > > the problem with SIGNAL_STOP_DEQUEUED I mentioned above. > > It's not at all clear this really does make sense. Yes, I already changed my mind, see another email from me ;) > I think this may > reflect a (common) misunderstanding of what the SIGCONT semantics are > (aside from ptrace). Resuming the process is not the action of > delivering SIGCONT. Yes. I was confused by "for a naive/legacy debugger", somehow I missed this doesn't work with the current code anyway, no need to add this feature. > So IMHO what makes most sense given what all the normal semantics are > is that PTRACE_CONT,SIGCONT does nothing magical, and generating a > fresh SIGCONT (i.e. kill) is the way you resume from job control stop. Exactly. All other things we discussed are "small details". This is the most noticeable change. 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/