From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754060AbYI2PKr (ORCPT ); Mon, 29 Sep 2008 11:10:47 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751658AbYI2PKh (ORCPT ); Mon, 29 Sep 2008 11:10:37 -0400 Received: from tomts40.bellnexxia.net ([209.226.175.97]:33953 "EHLO tomts40-srv.bellnexxia.net" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1751483AbYI2PKg (ORCPT ); Mon, 29 Sep 2008 11:10:36 -0400 X-IronPort-Anti-Spam-Filtered: true X-IronPort-Anti-Spam-Result: AgUFAL+L4EhMQWq+/2dsb2JhbACBYrowgWc Date: Mon, 29 Sep 2008 11:10:34 -0400 From: Mathieu Desnoyers To: Ingo Molnar Cc: Lai Jiangshan , Andrew Morton , "Paul E. McKenney" , Linux Kernel Mailing List , Steven Rostedt , Peter Zijlstra , "Frank Ch. Eigler" , Rusty Russell Subject: [PATCH] Markers : documentation fix teardown Message-ID: <20080929151034.GG11245@Krystal> References: <48E08B05.7030802@cn.fujitsu.com> <20080929082722.GB18663@elte.hu> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Content-Disposition: inline In-Reply-To: <20080929082722.GB18663@elte.hu> X-Editor: vi X-Info: http://krystal.dyndns.org:8080 X-Operating-System: Linux/2.6.21.3-grsec (i686) X-Uptime: 11:09:49 up 116 days, 19:50, 9 users, load average: 0.30, 0.56, 0.48 User-Agent: Mutt/1.5.16 (2007-06-11) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Document the need for a marker_synchronize_unregister() before the end of exit() to make sure every probe callers have exited the non preemptible section and thus are not executing the probe code anymore. Signed-off-by: Mathieu Desnoyers CC: Ingo Molnar CC: Rusty Russell CC: akpm@linux-foundation.org CC: "Frank Ch. Eigler" --- Documentation/markers.txt | 10 ++++++---- 1 file changed, 6 insertions(+), 4 deletions(-) Index: linux-2.6-lttng/Documentation/markers.txt =================================================================== --- linux-2.6-lttng.orig/Documentation/markers.txt 2008-07-31 09:11:13.000000000 -0400 +++ linux-2.6-lttng/Documentation/markers.txt 2008-07-31 09:20:57.000000000 -0400 @@ -50,10 +50,12 @@ Connecting a function (probe) to a marke to call) for the specific marker through marker_probe_register() and can be activated by calling marker_arm(). Marker deactivation can be done by calling marker_disarm() as many times as marker_arm() has been called. Removing a probe -is done through marker_probe_unregister(); it will disarm the probe and make -sure there is no caller left using the probe when it returns. Probe removal is -preempt-safe because preemption is disabled around the probe call. See the -"Probe example" section below for a sample probe module. +is done through marker_probe_unregister(); it will disarm the probe. +marker_synchronize_unregister() must be called before the end of the module exit +function to make sure there is no caller left using the probe. This, and the +fact that preemption is disabled around the probe call, make sure that probe +removal and module unload are safe. See the "Probe example" section below for a +sample probe module. The marker mechanism supports inserting multiple instances of the same marker. Markers can be put in inline functions, inlined static functions, and -- Mathieu Desnoyers OpenPGP key fingerprint: 8CD5 52C3 8E3C 4140 715F BA06 3F25 A8FE 3BAE 9A68