x86, ftrace: fix section mismatch in hw-branch-tracer

Fix an invalid memory reference problem when cpu hotplug support is
disabled and the hw-branch-tracer is set as current tracer.

Initializing the tracer calls bts_trace_init() which has already
been freed at this time.

Reported-by: Frederic Weisbecker <fweisbec@gmail.com>
Signed-off-by: Markus Metzger <markus.t.metzger@intel.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 3 insertions, 4 deletions

diff --git a/kernel/trace/trace_hw_branches.c b/kernel/trace/trace_hw_branches.c
index 3561aace075c..3335e807144b 100644
--- a/kernel/trace/trace_hw_branches.c
+++ b/kernel/trace/trace_hw_branches.c
@@ -127,20 +127,18 @@ static struct notifier_block bts_hotcpu_notifier __cpuinitdata = {
         .notifier_call = bts_hotcpu_handler
 };
 
-static int __cpuinit bts_trace_init(struct trace_array *tr)
+static int bts_trace_init(struct trace_array *tr)
 {
         hw_branch_trace = tr;
 
-        register_hotcpu_notifier(&bts_hotcpu_notifier);
         bts_trace_start(tr);
 
         return 0;
 }
 
-static void __cpuinit bts_trace_reset(struct trace_array *tr)
+static void bts_trace_reset(struct trace_array *tr)
 {
         bts_trace_stop(tr);
-        unregister_hotcpu_notifier(&bts_hotcpu_notifier);
 }
 
 static void bts_trace_print_header(struct seq_file *m)
@@ -299,6 +297,7 @@ struct tracer bts_tracer __read_mostly =
 
 __init static int init_bts_trace(void)
 {
+        register_hotcpu_notifier(&bts_hotcpu_notifier);
         return register_tracer(&bts_tracer);
 }
 device_initcall(init_bts_trace);