ftrace: Consistently restore trace function on sysctl enabling

If we reenable ftrace via syctl, we currently set ftrace_trace_function
based on the previous simplistic algorithm. This is inconsistent with
what update_ftrace_function does. So better call that helper instead.

Link: http://lkml.kernel.org/r/5151D26F.1070702@siemens.com

Cc: stable@vger.kernel.org
Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

1 files changed, 2 insertions, 6 deletions

diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index 6893d5a2bf08..cc4943c7ce6d 100644
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -4555,12 +4555,8 @@ ftrace_enable_sysctl(struct ctl_table *table, int write,
                 ftrace_startup_sysctl();
 
                 /* we are starting ftrace again */
-                if (ftrace_ops_list != &ftrace_list_end) {
-                        if (ftrace_ops_list->next == &ftrace_list_end)
-                                ftrace_trace_function = ftrace_ops_list->func;
-                        else
-                                ftrace_trace_function = ftrace_ops_list_func;
-                }
+                if (ftrace_ops_list != &ftrace_list_end)
+                        update_ftrace_function();
 
         } else {
                 /* stopping ftrace calls (just send to ftrace_stub) */