From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756444AbYKNXFg (ORCPT ); Fri, 14 Nov 2008 18:05:36 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1756129AbYKNXA5 (ORCPT ); Fri, 14 Nov 2008 18:00:57 -0500 Received: from smtp.polymtl.ca ([132.207.4.11]:57272 "EHLO smtp.polymtl.ca" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753616AbYKNXA4 (ORCPT ); Fri, 14 Nov 2008 18:00:56 -0500 Message-Id: <20081114224949.592960129@polymtl.ca> References: <20081114224733.364965865@polymtl.ca> User-Agent: quilt/0.46-1 Date: Fri, 14 Nov 2008 17:47:48 -0500 From: Mathieu Desnoyers To: Ingo Molnar , linux-kernel@vger.kernel.org Cc: akpm@linux-foundation.org, Linus Torvalds , Mathieu Desnoyers , Rusty Russell , "Frank Ch. Eigler" , Lai Jiangshan , Peter Zijlstra , Steven Rostedt Subject: [patch 15/16] Tracepoints : documentation fix teardown Content-Disposition: inline; filename=tracepoints-documentation-fix-teardown.patch X-Poly-FromMTA: (test.casi.polymtl.ca [132.207.72.60]) at Fri, 14 Nov 2008 23:00:02 +0000 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Need a tracepoint_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. Impact: documentation update. Signed-off-by: Mathieu Desnoyers CC: Rusty Russell CC: "Frank Ch. Eigler" CC: Ingo Molnar CC: Lai Jiangshan CC: Peter Zijlstra CC: Steven Rostedt --- Documentation/tracepoints.txt | 10 ++++++---- 1 file changed, 6 insertions(+), 4 deletions(-) Index: linux-2.6-lttng/Documentation/tracepoints.txt =================================================================== --- linux-2.6-lttng.orig/Documentation/tracepoints.txt 2008-11-14 17:18:59.000000000 -0500 +++ linux-2.6-lttng/Documentation/tracepoints.txt 2008-11-14 17:19:05.000000000 -0500 @@ -70,10 +70,12 @@ Where : Connecting a function (probe) to a tracepoint is done by providing a probe (function to call) for the specific tracepoint through register_trace_subsys_eventname(). Removing a probe is done through -unregister_trace_subsys_eventname(); it will remove the probe 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. +unregister_trace_subsys_eventname(); it will remove 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 tracepoint mechanism supports inserting multiple instances of the same tracepoint, but a single definition must be made of a given tracepoint name over -- Mathieu Desnoyers OpenPGP key fingerprint: 8CD5 52C3 8E3C 4140 715F BA06 3F25 A8FE 3BAE 9A68