Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757796Ab1F1MbT (ORCPT ); Tue, 28 Jun 2011 08:31:19 -0400 Received: from mail-ww0-f44.google.com ([74.125.82.44]:47384 "EHLO mail-ww0-f44.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757736Ab1F1Ma5 convert rfc822-to-8bit (ORCPT ); Tue, 28 Jun 2011 08:30:57 -0400 MIME-Version: 1.0 In-Reply-To: <20110628082512.GA3386@htj.dyndns.org> References: <201106262108.43011.vda.linux@googlemail.com> <20110626200442.GA16293@redhat.com> <20110627081139.GY30101@htj.dyndns.org> <20110627134713.GB3527@redhat.com> <20110627135252.GB30101@htj.dyndns.org> <20110627151827.GA6223@redhat.com> <20110628082512.GA3386@htj.dyndns.org> From: Denys Vlasenko Date: Tue, 28 Jun 2011 14:30:36 +0200 Message-ID: Subject: Re: [PATCH] ptrace: make former thread ID available via PTRACE_GETEVENTMSG after PTRACE_EVENT_EXEC stop (v.2) To: Tejun Heo Cc: Oleg Nesterov , linux-kernel@vger.kernel.org Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 8BIT Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1317 Lines: 31 On Tue, Jun 28, 2011 at 10:25 AM, Tejun Heo wrote: > On Mon, Jun 27, 2011 at 05:18:27PM +0200, Oleg Nesterov wrote: >> > and the only way to discover would be either comparing kernel >> > version or actually trying it - both aren't too nice. >> >> Fortunately, currently tracehook_report_exec() zeroes ->ptrace_message. >> At least this means that anything != 0 means it works. > > Yeah, but that's a pretty silly way to do it. ?If we make it depend on > PT_SEIZED, we can simply say "if seized, EXEC reports..." but as it > currently stands, it would go like "If the message is non-zero on > EXEC, it indicates... ?This behavior is valid since kernel version > x.x.x". This is true for any new addition to API. It starts from some kernel version. >?Maybe adding a guarantee that PTRACE_SEIZE capable kernel > always reports the old pid on EXEC but that would still seem > unnecessarily complicated. ?It isn't a bug fix. ?I don't see much > point in introducing new behavior separately. This new feature looks orthogonal to PTRACE_SEIZE to me. -- vda -- 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/