[PATCH v2 35/40] tracing: Reverse the order event_mutex/trace_types_lock are taken

[Tom Zanussi]

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.zanu...@linux.intel.com>
---
 kernel/trace/trace_events.c | 16 ++++++++--------
 1 file changed, 8 insertions(+), 8 deletions(-)

diff --git a/kernel/trace/trace_events.c b/kernel/trace/trace_events.c
index c93540c..889802c 100644
--- a/kernel/trace/trace_events.c
+++ b/kernel/trace/trace_events.c
@@ -1406,8 +1406,8 @@ static int subsystem_open(struct inode *inode, struct 
file *filp)
                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) {
@@ -1421,8 +1421,8 @@ static int subsystem_open(struct inode *inode, struct 
file *filp)
                }
        }
  exit_loop:
-       mutex_unlock(&event_mutex);
        mutex_unlock(&trace_types_lock);
+       mutex_unlock(&event_mutex);
 
        if (!system)
                return -ENODEV;
@@ -2294,15 +2294,15 @@ void trace_event_eval_update(struct trace_eval_map 
**map, int len)
 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;
 }
 
@@ -2356,13 +2356,13 @@ int trace_remove_event_call(struct trace_event_call 
*call)
 {
        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;
 }
@@ -2424,8 +2424,8 @@ static int trace_module_notify(struct notifier_block 
*self,
 {
        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);
@@ -2434,8 +2434,8 @@ static int trace_module_notify(struct notifier_block 
*self,
                trace_module_remove_events(mod);
                break;
        }
-       mutex_unlock(&event_mutex);
        mutex_unlock(&trace_types_lock);
+       mutex_unlock(&event_mutex);
 
        return 0;
 }
-- 
1.9.3