From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755150AbcHSCEr (ORCPT ); Thu, 18 Aug 2016 22:04:47 -0400 Received: from mx1.redhat.com ([209.132.183.28]:56684 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755139AbcHSCEJ (ORCPT ); Thu, 18 Aug 2016 22:04:09 -0400 Date: Thu, 18 Aug 2016 18:23:11 +0200 From: Oleg Nesterov To: Keno Fischer Cc: roland@hack.frob.com, linux-kernel@vger.kernel.org, Tejun Heo Subject: Re: ptrace group stop signal number not reset before PTRACE_INTERRUPT is delivered? Message-ID: <20160818162311.GA27883@redhat.com> References: <20160818143750.GA24070@redhat.com> <20160818153806.GA25492@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20160818153806.GA25492@redhat.com> User-Agent: Mutt/1.5.18 (2008-05-17) X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.28]); Thu, 18 Aug 2016 16:23:30 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Damn, forgot to mention... On 08/18, Oleg Nesterov wrote: > > Damn. I'll try to think more, but I simply can't decide what do we > actually want in this case. Yes, but at least > Further, the current behavior seems to make it > very hard (impossible?) to reliably tell a true group-stop from a > PTRACE_INTERRUPT generated one. is not true or I misunderstood... PTRACE_INTERRUPT doesn't lead to group-stop, it stops the tracee individually. And you if you get PTRACE_EVENT_STOP and WSTOPSIG() == SIGTTIN after PTRACE_INTERRUPT, you know that the tracee did not report the "new" SIGTTIN. Or I missed your point? Oleg.