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Commit 12ecef0c authored by Steven Rostedt (VMware)'s avatar Steven Rostedt (VMware)
Browse files

tracing: Reverse the order of trace_types_lock and event_mutex 

In order to make future changes where we need to call
tracing_set_clock() from within an event command, the order of
trace_types_lock and event_mutex must be reversed, as the event command
will hold event_mutex and the trace_types_lock is taken from within
tracing_set_clock().

Link: http://lkml.kernel.org/r/20170921162249.0dde3dca@gandalf.local.home



Requested-by: default avatarTom Zanussi <tom.zanussi@linux.intel.com>
Signed-off-by: default avatarSteven Rostedt (VMware) <rostedt@goodmis.org>
parent 6e7a2398

kernel/trace/trace.c

+5 −0
Original line number Diff line number Diff line
@@ -7687,6 +7687,7 @@ static int instance_mkdir(const char *name) 
	struct trace_array *tr;

	int ret;



	mutex_lock(&event_mutex);

	mutex_lock(&trace_types_lock);



	ret = -EEXIST;
@@ -7742,6 +7743,7 @@ static int instance_mkdir(const char *name) 
	list_add(&tr->list, &ftrace_trace_arrays);



	mutex_unlock(&trace_types_lock);

	mutex_unlock(&event_mutex);



	return 0;
@@ -7753,6 +7755,7 @@ static int instance_mkdir(const char *name) 


 out_unlock:

	mutex_unlock(&trace_types_lock);

	mutex_unlock(&event_mutex);



	return ret;
@@ -7765,6 +7768,7 @@ static int instance_rmdir(const char *name) 
	int ret;

	int i;



	mutex_lock(&event_mutex);

	mutex_lock(&trace_types_lock);



	ret = -ENODEV;
@@ -7810,6 +7814,7 @@ static int instance_rmdir(const char *name) 


 out_unlock:

	mutex_unlock(&trace_types_lock);

	mutex_unlock(&event_mutex);



	return ret;

}

kernel/trace/trace_events.c

+15 −16
Original line number Diff line number Diff line
@@ -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 @@ static void __add_event_to_tracers(struct trace_event_call *call); 
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;

}
@@ -2950,24 +2950,24 @@ create_event_toplevel_files(struct dentry *parent, struct trace_array *tr) 
 * creates the event hierachry in the @parent/events directory.

 *

 * Returns 0 on success.

 *

 * Must be called with event_mutex held.

 */

int event_trace_add_tracer(struct dentry *parent, struct trace_array *tr)

{

	int ret;



	mutex_lock(&event_mutex);

	lockdep_assert_held(&event_mutex);



	ret = create_event_toplevel_files(parent, tr);

	if (ret)

		goto out_unlock;

		goto out;



	down_write(&trace_event_sem);

	__trace_add_event_dirs(tr);

	up_write(&trace_event_sem);



 out_unlock:

	mutex_unlock(&event_mutex);



 out:

	return ret;

}
@@ -2996,9 +2996,10 @@ early_event_add_tracer(struct dentry *parent, struct trace_array *tr) 
	return ret;

}



/* Must be called with event_mutex held */

int event_trace_del_tracer(struct trace_array *tr)

{

	mutex_lock(&event_mutex);

	lockdep_assert_held(&event_mutex);



	/* Disable any event triggers and associated soft-disabled events */

	clear_event_triggers(tr);
@@ -3019,8 +3020,6 @@ int event_trace_del_tracer(struct trace_array *tr) 


	tr->event_dir = NULL;



	mutex_unlock(&event_mutex);



	return 0;

}