From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1765106AbZDAOVW (ORCPT ); Wed, 1 Apr 2009 10:21:22 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1764147AbZDAOUj (ORCPT ); Wed, 1 Apr 2009 10:20:39 -0400 Received: from hrndva-omtalb.mail.rr.com ([71.74.56.123]:43461 "EHLO hrndva-omtalb.mail.rr.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1761587AbZDAOUh (ORCPT ); Wed, 1 Apr 2009 10:20:37 -0400 Message-Id: <20090401142033.634402978@goodmis.org> References: <20090401141949.714854885@goodmis.org> User-Agent: quilt/0.46-1 Date: Wed, 01 Apr 2009 10:19:50 -0400 From: Steven Rostedt To: linux-kernel@vger.kernel.org Cc: Ingo Molnar , Andrew Morton , Steven Rostedt Subject: [PATCH 1/2] function-graph: allow unregistering twice Content-Disposition: inline; filename=0001-function-graph-allow-unregistering-twice.patch Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Steven Rostedt Impact: fix to permanent disabling of function graph tracer There should be nothing to prevent a tracer from unregistering a function graph callback more than once. This can simplify error paths. But currently, the counter does not account for mulitple unregistering of the function graph callback. If it happens, the function graph tracer will be permanently disabled. Signed-off-by: Steven Rostedt --- kernel/trace/ftrace.c | 4 ++++ 1 files changed, 4 insertions(+), 0 deletions(-) diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c index 1752a63..f1ed080 100644 --- a/kernel/trace/ftrace.c +++ b/kernel/trace/ftrace.c @@ -2719,6 +2719,9 @@ void unregister_ftrace_graph(void) { mutex_lock(&ftrace_lock); + if (!unlikely(atomic_read(&ftrace_graph_active))) + goto out; + atomic_dec(&ftrace_graph_active); unregister_trace_sched_switch(ftrace_graph_probe_sched_switch); ftrace_graph_return = (trace_func_graph_ret_t)ftrace_stub; @@ -2726,6 +2729,7 @@ void unregister_ftrace_graph(void) ftrace_shutdown(FTRACE_STOP_FUNC_RET); unregister_pm_notifier(&ftrace_suspend_notifier); + out: mutex_unlock(&ftrace_lock); } -- 1.6.2.1 --