patches/0035-tracing-Reverse-the-order-event_mutex-trace_types_lo.patch

From: Tom Zanussi <tom.zanussi@linux.intel.com>
Date: Tue, 5 Sep 2017 16:57:47 -0500
Subject: [PATCH 35/40] tracing: Reverse the order event_mutex/trace_types_lock
 are taken

Change the order event_mutex and trace_types_lock are taken, to avoid
circular dependencies and lockdep spew.

Changing the order shouldn't matter to any current code, but does to
anything that takes the event_mutex first and then trace_types_lock.
This is the case when calling tracing_set_clock from inside an event
command, which already holds the event_mutex.

Signed-off-by: Tom Zanussi <tom.zanussi@linux.intel.com>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
---
 kernel/trace/trace_events.c |   16 ++++++++--------
 1 file changed, 8 insertions(+), 8 deletions(-)

--- a/kernel/trace/trace_events.c
+++ b/kernel/trace/trace_events.c
@@ -1366,8 +1366,8 @@ static int subsystem_open(struct inode *
 		return -ENODEV;
 
 	/* Make sure the system still exists */
-	mutex_lock(&trace_types_lock);
 	mutex_lock(&event_mutex);
+	mutex_lock(&trace_types_lock);
 	list_for_each_entry(tr, &ftrace_trace_arrays, list) {
 		list_for_each_entry(dir, &tr->systems, list) {
 			if (dir == inode->i_private) {
@@ -1381,8 +1381,8 @@ static int subsystem_open(struct inode *
 		}
 	}
  exit_loop:
-	mutex_unlock(&event_mutex);
 	mutex_unlock(&trace_types_lock);
+	mutex_unlock(&event_mutex);
 
 	if (!system)
 		return -ENODEV;
@@ -2250,15 +2250,15 @@ static void __add_event_to_tracers(struc
 int trace_add_event_call(struct trace_event_call *call)
 {
 	int ret;
-	mutex_lock(&trace_types_lock);
 	mutex_lock(&event_mutex);
+	mutex_lock(&trace_types_lock);
 
 	ret = __register_event(call, NULL);
 	if (ret >= 0)
 		__add_event_to_tracers(call);
 
-	mutex_unlock(&event_mutex);
 	mutex_unlock(&trace_types_lock);
+	mutex_unlock(&event_mutex);
 	return ret;
 }
 
@@ -2312,13 +2312,13 @@ int trace_remove_event_call(struct trace
 {
 	int ret;
 
-	mutex_lock(&trace_types_lock);
 	mutex_lock(&event_mutex);
+	mutex_lock(&trace_types_lock);
 	down_write(&trace_event_sem);
 	ret = probe_remove_event_call(call);
 	up_write(&trace_event_sem);
-	mutex_unlock(&event_mutex);
 	mutex_unlock(&trace_types_lock);
+	mutex_unlock(&event_mutex);
 
 	return ret;
 }
@@ -2385,8 +2385,8 @@ static int trace_module_notify(struct no
 {
 	struct module *mod = data;
 
-	mutex_lock(&trace_types_lock);
 	mutex_lock(&event_mutex);
+	mutex_lock(&trace_types_lock);
 	switch (val) {
 	case MODULE_STATE_COMING:
 		trace_module_add_events(mod);
@@ -2395,8 +2395,8 @@ static int trace_module_notify(struct no
 		trace_module_remove_events(mod);
 		break;
 	}
-	mutex_unlock(&event_mutex);
 	mutex_unlock(&trace_types_lock);
+	mutex_unlock(&event_mutex);
 
 	return 0;
 }