From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756158AbaF3Q4e (ORCPT ); Mon, 30 Jun 2014 12:56:34 -0400 Received: from e28smtp06.in.ibm.com ([122.248.162.6]:42881 "EHLO e28smtp06.in.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753948AbaF3Q4d (ORCPT ); Mon, 30 Jun 2014 12:56:33 -0400 Date: Mon, 30 Jun 2014 22:26:26 +0530 From: Srikar Dronamraju To: Oleg Nesterov Cc: Steven Rostedt , Masami Hiramatsu , Namhyung Kim , Tom Zanussi , "zhangwei(Jovi)" , linux-kernel@vger.kernel.org Subject: Re: [PATCH 1/4] tracing/uprobes: Revert "Support mix of ftrace and perf" Message-ID: <20140630165626.GA5619@linux.vnet.ibm.com> Reply-To: Srikar Dronamraju References: <20140627170116.GA18298@redhat.com> <20140627170136.GA18319@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline In-Reply-To: <20140627170136.GA18319@redhat.com> User-Agent: Mutt/1.5.21 (2010-09-15) X-TM-AS-MML: disable X-Content-Scanned: Fidelis XPS MAILER x-cbid: 14063016-9574-0000-0000-00000E9E7B11 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org * Oleg Nesterov [2014-06-27 19:01:36]: > This reverts commit 43fe98913c9f67e3b523615ee3316f9520a623e0. > > This patch is very wrong. Firstly, this change leads to unbalanced > uprobe_unregister(). Just for example, > > # perf probe -x /lib/libc.so.6 syscall > # echo 1 >> /sys/kernel/debug/tracing/events/probe_libc/enable > # perf record -e probe_libc:syscall whatever > > after that uprobe is dead (unregistered) but the user of ftrace/perf > can't know this, and it looks as if nobody hits this probe. > > This would be easy to fix, but there are other reasons why it is not > simple to mix ftrace and perf. If nothing else, they can't share the > same ->consumer.filter. This is fixable too, but probably we need to > fix the poorly designed uprobe_register() interface first. At least > "register" and "apply" should be clearly separated. > > Cc: stable@vger.kernel.org # v3.14 > Signed-off-by: Oleg Nesterov Acked-by: Srikar Dronamraju -- Thanks and Regards Srikar Dronamraju