ftrace: Have function tracing start in early boot up

Register the function tracer right after the tracing buffers are initialized
in early boot up. This will allow function tracing to begin early if it is
enabled via the kernel command line.

Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>

diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 68a6f78f6862710eade1fd1f5b705ccd61b4def7..4fa8e8f3c76538b794e2780bca40e99225078c5a 100644 (file)
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -8036,6 +8036,9 @@ __init static int tracer_alloc_buffers(void)
 
        register_tracer(&nop_trace);
 
+       /* Function tracing may start here (via kernel command line) */
+       init_function_trace();
+
        /* All seems OK, enable tracing */
        tracing_disabled = 0;
 

diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h
index ae1cce91fead25a065899109e426a6cc1e597d28..571acee52a325e520726fd3670313feca21e6bb8 100644 (file)
--- a/kernel/trace/trace.h
+++ b/kernel/trace/trace.h
@@ -896,6 +896,7 @@ int using_ftrace_ops_list_func(void);
 void ftrace_init_tracefs(struct trace_array *tr, struct dentry *d_tracer);
 void ftrace_init_tracefs_toplevel(struct trace_array *tr,
                                  struct dentry *d_tracer);
+int init_function_trace(void);
 #else
 static inline int ftrace_trace_task(struct trace_array *tr)
 {
@@ -914,6 +915,7 @@ ftrace_init_global_array_ops(struct trace_array *tr) { }
 static inline void ftrace_reset_array_ops(struct trace_array *tr) { }
 static inline void ftrace_init_tracefs(struct trace_array *tr, struct dentry *d) { }
 static inline void ftrace_init_tracefs_toplevel(struct trace_array *tr, struct dentry *d) { }
+static inline int init_function_trace(void) { return 0; }
 /* ftace_func_t type is not defined, use macro instead of static inline */
 #define ftrace_init_array_ops(tr, func) do { } while (0)
 #endif /* CONFIG_FUNCTION_TRACER */

diff --git a/kernel/trace/trace_functions.c b/kernel/trace/trace_functions.c
index 0efa00d80623db3de438a5233a8ee6f84fae65ed..4199ca61b0e5823e1169450a6cd66cde78a04bdd 100644 (file)
--- a/kernel/trace/trace_functions.c
+++ b/kernel/trace/trace_functions.c
@@ -687,9 +687,8 @@ static inline int init_func_cmd_traceon(void)
 }
 #endif /* CONFIG_DYNAMIC_FTRACE */
 
-static __init int init_function_trace(void)
+__init int init_function_trace(void)
 {
        init_func_cmd_traceon();
        return register_tracer(&function_trace);
 }
-core_initcall(init_function_trace);