Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758271AbZC0OiW (ORCPT ); Fri, 27 Mar 2009 10:38:22 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1755852AbZC0OiG (ORCPT ); Fri, 27 Mar 2009 10:38:06 -0400 Received: from mx2.redhat.com ([66.187.237.31]:44337 "EHLO mx2.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755985AbZC0OiF (ORCPT ); Fri, 27 Mar 2009 10:38:05 -0400 Date: Fri, 27 Mar 2009 15:34:35 +0100 From: Oleg Nesterov To: Markus Metzger Cc: linux-kernel@vger.kernel.org, mingo@elte.hu, tglx@linutronix.de, hpa@zytor.com, markus.t.metzger@gmail.com, roland@redhat.com, eranian@googlemail.com, juan.villacis@intel.com, ak@linux.jf.intel.com Subject: Re: [patch 3/14] x86, ptrace, bts: stop bts tracing early in do_exit Message-ID: <20090327143435.GD14504@redhat.com> References: <20090327095525.A11052@sedona.ch.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20090327095525.A11052@sedona.ch.intel.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: 788 Lines: 27 On 03/27, Markus Metzger wrote: > > +static void ptrace_bts_exit(void) > +{ > + if (unlikely(!list_empty(¤t->ptraced))) > + ptrace_bts_exit_tracer(); > + > + if (unlikely(current->bts)) > + ptrace_bts_exit_tracee(); > +} Could you explain why do we need ptrace_bts_exit_tracee() ? If current is traced, the tracer should do ptrace_bts_release() eventually, no? And if we really need to do ptrace_bts_exit_tracee(), then "if (unlikely(current->bts))" check is racy. The tracer can do PTRACE_BTS_CONFIG right after the check. 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/