4 files changed, 12 insertions, 3 deletions

diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index e4c40c868d67..50d7018163f6 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -3251,6 +3251,8 @@ __init static int tracer_alloc_buffers(void)
 
         register_tracer(&nop_trace);
 #ifdef CONFIG_BOOT_TRACER
+        /* We don't want to launch sched_switch tracer yet */
+        global_trace.ctrl = 0;
         register_tracer(&boot_tracer);
         current_trace = &boot_tracer;
         current_trace->init(&global_trace);
diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h
index 8465ad052707..9911277b268b 100644
--- a/kernel/trace/trace.h
+++ b/kernel/trace/trace.h
@@ -49,6 +49,7 @@ struct ftrace_entry {
         unsigned long           parent_ip;
 };
 extern struct tracer boot_tracer;
+extern struct tracer sched_switch_trace; /* Used by the boot tracer */
 
 /*
  * Context switch trace entry - which task (and prio) we switched from/to:
diff --git a/kernel/trace/trace_boot.c b/kernel/trace/trace_boot.c
index d104d5b46413..6bbc8794a6df 100644
--- a/kernel/trace/trace_boot.c
+++ b/kernel/trace/trace_boot.c
@@ -27,10 +27,14 @@ void start_boot_trace(void)
 
 void enable_boot_trace(void)
 {
+        if (pre_initcalls_finished)
+                tracing_start_cmdline_record();
 }
 
 void disable_boot_trace(void)
 {
+        if (pre_initcalls_finished)
+                tracing_stop_cmdline_record();
 }
 
 void reset_boot_trace(struct trace_array *tr)
@@ -45,6 +49,8 @@ static void boot_trace_init(struct trace_array *tr)
 
         for_each_cpu_mask(cpu, cpu_possible_map)
                 tracing_reset(tr, cpu);
+
+        sched_switch_trace.init(tr);
 }
 
 static void boot_trace_ctrl_update(struct trace_array *tr)
diff --git a/kernel/trace/trace_sched_switch.c b/kernel/trace/trace_sched_switch.c
index 96620c714300..9d7bdac331dd 100644
--- a/kernel/trace/trace_sched_switch.c
+++ b/kernel/trace/trace_sched_switch.c
@@ -127,6 +127,7 @@ static void tracing_start_sched_switch(void)
         long ref;
 
         mutex_lock(&tracepoint_mutex);
+        tracer_enabled = 1;
         ref = atomic_inc_return(&sched_ref);
         if (ref == 1)
                 tracing_sched_register();
@@ -138,6 +139,7 @@ static void tracing_stop_sched_switch(void)
         long ref;
 
         mutex_lock(&tracepoint_mutex);
+        tracer_enabled = 0;
         ref = atomic_dec_and_test(&sched_ref);
         if (ref)
                 tracing_sched_unregister();
@@ -158,12 +160,10 @@ static void start_sched_trace(struct trace_array *tr)
 {
         sched_switch_reset(tr);
         tracing_start_cmdline_record();
-        tracer_enabled = 1;
 }
 
 static void stop_sched_trace(struct trace_array *tr)
 {
-        tracer_enabled = 0;
         tracing_stop_cmdline_record();
 }
 
@@ -190,7 +190,7 @@ static void sched_switch_trace_ctrl_update(struct trace_array *tr)
                 stop_sched_trace(tr);
 }
 
-static struct tracer sched_switch_trace __read_mostly =
+struct tracer sched_switch_trace __read_mostly =
 {
         .name           = "sched_switch",
         .init           = sched_switch_trace_init,