[PATCH] tracing: make tracer_init_tracefs initcall asynchronous

[Mark-PK Tsai]

tracer_init_tracefs() is slow especially when there are
lots of trace events.
Create a kthread to do tracer_init_tracefs() asynchronously
to speed up the initialization of kernel and move the
related functions and variables out of init section.

Signed-off-by: Mark-PK Tsai <mark-pk.tsai@xxxxxxxxxxxx>
---
 fs/tracefs/inode.c          |  8 ++++----
 kernel/trace/ftrace.c       | 12 ++++++------
 kernel/trace/trace.c        | 21 ++++++++++++++++-----
 kernel/trace/trace_events.c |  2 +-
 4 files changed, 27 insertions(+), 16 deletions(-)

diff --git a/fs/tracefs/inode.c b/fs/tracefs/inode.c
index de7252715b12..9a713d6bcb7e 100644
--- a/fs/tracefs/inode.c
+++ b/fs/tracefs/inode.c
@@ -561,10 +561,10 @@ struct dentry *tracefs_create_dir(const char *name, struct dentry *parent)
  *
  * Returns the dentry of the instances directory.
  */
-__init struct dentry *tracefs_create_instance_dir(const char *name,
-					  struct dentry *parent,
-					  int (*mkdir)(const char *name),
-					  int (*rmdir)(const char *name))
+struct dentry *tracefs_create_instance_dir(const char *name,
+					   struct dentry *parent,
+					   int (*mkdir)(const char *name),
+					   int (*rmdir)(const char *name))
 {
 	struct dentry *dentry;
 
diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index a4b462b6f944..197630cbd5dd 100644
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -940,7 +940,7 @@ static const struct file_operations ftrace_profile_fops = {
 };
 
 /* used to initialize the real stat files */
-static struct tracer_stat function_stats __initdata = {
+static struct tracer_stat function_stats = {
 	.name		= "functions",
 	.stat_start	= function_stat_start,
 	.stat_next	= function_stat_next,
@@ -949,7 +949,7 @@ static struct tracer_stat function_stats __initdata = {
 	.stat_show	= function_stat_show
 };
 
-static __init void ftrace_profile_tracefs(struct dentry *d_tracer)
+static void ftrace_profile_tracefs(struct dentry *d_tracer)
 {
 	struct ftrace_profile_stat *stat;
 	struct dentry *entry;
@@ -991,7 +991,7 @@ static __init void ftrace_profile_tracefs(struct dentry *d_tracer)
 }
 
 #else /* CONFIG_FUNCTION_PROFILER */
-static __init void ftrace_profile_tracefs(struct dentry *d_tracer)
+static void ftrace_profile_tracefs(struct dentry *d_tracer)
 {
 }
 #endif /* CONFIG_FUNCTION_PROFILER */
@@ -6359,7 +6359,7 @@ void ftrace_destroy_filter_files(struct ftrace_ops *ops)
 	mutex_unlock(&ftrace_lock);
 }
 
-static __init int ftrace_init_dyn_tracefs(struct dentry *d_tracer)
+static int ftrace_init_dyn_tracefs(struct dentry *d_tracer)
 {
 
 	trace_create_file("available_filter_functions", TRACE_MODE_READ,
@@ -7754,8 +7754,8 @@ void ftrace_init_tracefs(struct trace_array *tr, struct dentry *d_tracer)
 			  d_tracer, tr, &ftrace_no_pid_fops);
 }
 
-void __init ftrace_init_tracefs_toplevel(struct trace_array *tr,
-					 struct dentry *d_tracer)
+void ftrace_init_tracefs_toplevel(struct trace_array *tr,
+				  struct dentry *d_tracer)
 {
 	/* Only the top level directory has the dyn_tracefs and profile */
 	WARN_ON(!(tr->flags & TRACE_ARRAY_FL_GLOBAL));
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index eb44418574f9..f55da82060e2 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -9562,10 +9562,10 @@ int tracing_init_dentry(void)
 extern struct trace_eval_map *__start_ftrace_eval_maps[];
 extern struct trace_eval_map *__stop_ftrace_eval_maps[];
 
-static struct workqueue_struct *eval_map_wq __initdata;
-static struct work_struct eval_map_work __initdata;
+static struct workqueue_struct *eval_map_wq;
+static struct work_struct eval_map_work;
 
-static void __init eval_map_work_func(struct work_struct *work)
+static void eval_map_work_func(struct work_struct *work)
 {
 	int len;
 
@@ -9573,7 +9573,7 @@ static void __init eval_map_work_func(struct work_struct *work)
 	trace_insert_eval_map(NULL, __start_ftrace_eval_maps, len);
 }
 
-static int __init trace_eval_init(void)
+static int trace_eval_init(void)
 {
 	INIT_WORK(&eval_map_work, eval_map_work_func);
 
@@ -9671,7 +9671,7 @@ static struct notifier_block trace_module_nb = {
 };
 #endif /* CONFIG_MODULES */
 
-static __init int tracer_init_tracefs(void)
+static int tracefs_init(void *data)
 {
 	int ret;
 
@@ -9721,6 +9721,17 @@ static __init int tracer_init_tracefs(void)
 	return 0;
 }
 
+static __init int tracer_init_tracefs(void)
+{
+	struct task_struct *thread;
+
+	thread = kthread_run(tracefs_init, NULL, "tracefs_init");
+	if (IS_ERR(thread))
+		return PTR_ERR(thread);
+
+	return 0;
+}
+
 fs_initcall(tracer_init_tracefs);
 
 static int trace_panic_handler(struct notifier_block *this,
diff --git a/kernel/trace/trace_events.c b/kernel/trace/trace_events.c
index 3147614c1812..fe055bef1e8f 100644
--- a/kernel/trace/trace_events.c
+++ b/kernel/trace/trace_events.c
@@ -3687,7 +3687,7 @@ static __init int event_trace_init_fields(void)
 	return 0;
 }
 
-__init int event_trace_init(void)
+int event_trace_init(void)
 {
 	struct trace_array *tr;
 	struct dentry *entry;
-- 
2.18.0