linux-kernel - [tip:tracing/core] tracing/profile: fix profile_disable vs module

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Date:	Sun, 13 Sep 2009 15:02:48 GMT
From:	tip-bot for Li Zefan <lizf@...fujitsu.com>
To:	linux-tip-commits@...r.kernel.org
Cc:	linux-kernel@...r.kernel.org, hpa@...or.com, mingo@...hat.com,
	rostedt@...dmis.org, lizf@...fujitsu.com, tglx@...utronix.de
Subject: [tip:tracing/core] tracing/profile: fix profile_disable vs module_unload

Commit-ID:  558e6547e4b8a2b13608a24a9d3679802f91c4c7
Gitweb:     http://git.kernel.org/tip/558e6547e4b8a2b13608a24a9d3679802f91c4c7
Author:     Li Zefan <lizf@...fujitsu.com>
AuthorDate: Mon, 24 Aug 2009 12:19:47 +0800
Committer:  Steven Rostedt <rostedt@...dmis.org>
CommitDate: Sat, 12 Sep 2009 22:28:38 -0400

tracing/profile: fix profile_disable vs module_unload

If the correspoding module is unloaded before ftrace_profile_disable()
is called, event->profile_disable() won't be called, which can
cause oops:

  # insmod trace-events-sample.ko
  # perf record -f -a -e sample:foo_bar sleep 3 &
  # sleep 1
  # rmmod trace_events_sample
  # insmod trace-events-sample.ko
  OOPS!

Signed-off-by: Li Zefan <lizf@...fujitsu.com>
LKML-Reference: <4A9214E3.2070807@...fujitsu.com>
Signed-off-by: Steven Rostedt <rostedt@...dmis.org>


---
 kernel/trace/trace_event_profile.c |    5 ++++-
 1 files changed, 4 insertions(+), 1 deletions(-)

diff --git a/kernel/trace/trace_event_profile.c b/kernel/trace/trace_event_profile.c
index 11ba5bb..55a25c9 100644
--- a/kernel/trace/trace_event_profile.c
+++ b/kernel/trace/trace_event_profile.c
@@ -5,6 +5,7 @@
  *
  */
 
+#include <linux/module.h>
 #include "trace.h"
 
 int ftrace_profile_enable(int event_id)
@@ -14,7 +15,8 @@ int ftrace_profile_enable(int event_id)
 
 	mutex_lock(&event_mutex);
 	list_for_each_entry(event, &ftrace_events, list) {
-		if (event->id == event_id && event->profile_enable) {
+		if (event->id == event_id && event->profile_enable &&
+		    try_module_get(event->mod)) {
 			ret = event->profile_enable(event);
 			break;
 		}
@@ -32,6 +34,7 @@ void ftrace_profile_disable(int event_id)
 	list_for_each_entry(event, &ftrace_events, list) {
 		if (event->id == event_id) {
 			event->profile_disable(event);
+			module_put(event->mod);
 			break;
 		}
 	}
--
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