tracing: Introduce remove_event_file_dir()

Preparation for the next patch. Extract the common code from
remove_event_from_tracers() and __trace_remove_event_dirs()
into the new helper, remove_event_file_dir().

The patch looks more complicated than it actually is, it also
moves remove_subsystem() up to avoid the forward declaration.

Link: http://lkml.kernel.org/r/20130726172547.GA3629@redhat.com

Reviewed-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

kernel/trace/trace_events.c

@@ -409,11 +409,31 @@ static void put_system(struct ftrace_subsystem_dir *dir)
 	mutex_unlock(&event_mutex);
 }
 
+static void remove_subsystem(struct ftrace_subsystem_dir *dir)
+{
+	if (!dir)
+		return;
+
+	if (!--dir->nr_events) {
+		debugfs_remove_recursive(dir->entry);
+		list_del(&dir->list);
+		__put_system_dir(dir);
+	}
+}
+
 static void *event_file_data(struct file *filp)
 {
 	return ACCESS_ONCE(file_inode(filp)->i_private);
 }
 
+static void remove_event_file_dir(struct ftrace_event_file *file)
+{
+	list_del(&file->list);
+	debugfs_remove_recursive(file->dir);
+	remove_subsystem(file->system);
+	kmem_cache_free(file_cachep, file);
+}
+
 /*
  * Open and update trace_array ref count.
  * Must have the current trace_array passed to it.
@@ -1549,33 +1569,16 @@ event_create_dir(struct dentry *parent,
 	return 0;
 }
 
-static void remove_subsystem(struct ftrace_subsystem_dir *dir)
-{
-	if (!dir)
-		return;
-
-	if (!--dir->nr_events) {
-		debugfs_remove_recursive(dir->entry);
-		list_del(&dir->list);
-		__put_system_dir(dir);
-	}
-}
-
 static void remove_event_from_tracers(struct ftrace_event_call *call)
 {
 	struct ftrace_event_file *file;
 	struct trace_array *tr;
 
 	do_for_each_event_file_safe(tr, file) {
-
 		if (file->event_call != call)
 			continue;
 
-		list_del(&file->list);
+		remove_event_file_dir(file);
-		debugfs_remove_recursive(file->dir);
-		remove_subsystem(file->system);
-		kmem_cache_free(file_cachep, file);
-
 		/*
 		 * The do_for_each_event_file_safe() is
 		 * a double loop. After finding the call for this
@@ -2305,12 +2308,8 @@ __trace_remove_event_dirs(struct trace_array *tr)
 {
 	struct ftrace_event_file *file, *next;
 
-	list_for_each_entry_safe(file, next, &tr->events, list) {
+	list_for_each_entry_safe(file, next, &tr->events, list)
-		list_del(&file->list);
+		remove_event_file_dir(file);
-		debugfs_remove_recursive(file->dir);
-		remove_subsystem(file->system);
-		kmem_cache_free(file_cachep, file);
-	}
 }
 
 static void