3 files changed, 11 insertions, 12 deletions

diff --git a/kernel/trace/Kconfig b/kernel/trace/Kconfig
index dde1d46f77e5..28f2644484d9 100644
--- a/kernel/trace/Kconfig
+++ b/kernel/trace/Kconfig
@@ -164,9 +164,8 @@ config BOOT_TRACER
           representation of the delays during initcalls - but the raw
           /debug/tracing/trace text output is readable too.
 
-          ( Note that tracing self tests can't be enabled if this tracer is
-            selected, because the self-tests are an initcall as well and that
-            would invalidate the boot trace. )
+          You must pass in ftrace=initcall to the kernel command line
+          to enable this on bootup.
 
 config TRACE_BRANCH_PROFILING
         bool "Trace likely/unlikely profiler"
@@ -326,7 +325,7 @@ config FTRACE_SELFTEST
 
 config FTRACE_STARTUP_TEST
         bool "Perform a startup test on ftrace"
-        depends on TRACING && DEBUG_KERNEL && !BOOT_TRACER
+        depends on TRACING && DEBUG_KERNEL
         select FTRACE_SELFTEST
         help
           This option performs a series of startup tests on ftrace. On bootup
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 2c720c79bc60..40edef4255c5 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -3167,12 +3167,9 @@ __init static int tracer_alloc_buffers(void)
         trace_init_cmdlines();
 
         register_tracer(&nop_trace);
+        current_trace = &nop_trace;
 #ifdef CONFIG_BOOT_TRACER
         register_tracer(&boot_tracer);
-        current_trace = &boot_tracer;
-        current_trace->init(&global_trace);
-#else
-        current_trace = &nop_trace;
 #endif
         /* All seems OK, enable tracing */
         tracing_disabled = 0;
diff --git a/kernel/trace/trace_boot.c b/kernel/trace/trace_boot.c
index 0e94b3d091f7..1f07895977a0 100644
--- a/kernel/trace/trace_boot.c
+++ b/kernel/trace/trace_boot.c
@@ -28,13 +28,13 @@ void start_boot_trace(void)
 
 void enable_boot_trace(void)
 {
-        if (pre_initcalls_finished)
+        if (boot_trace && pre_initcalls_finished)
                 tracing_start_sched_switch_record();
 }
 
 void disable_boot_trace(void)
 {
-        if (pre_initcalls_finished)
+        if (boot_trace && pre_initcalls_finished)
                 tracing_stop_sched_switch_record();
 }
 
@@ -43,6 +43,9 @@ static int boot_trace_init(struct trace_array *tr)
         int cpu;
         boot_trace = tr;
 
+        if (!tr)
+                return 0;
+
         for_each_cpu(cpu, cpu_possible_mask)
                 tracing_reset(tr, cpu);
 
@@ -132,7 +135,7 @@ void trace_boot_call(struct boot_trace_call *bt, initcall_t fn)
         unsigned long irq_flags;
         struct trace_array *tr = boot_trace;
 
-        if (!pre_initcalls_finished)
+        if (!tr || !pre_initcalls_finished)
                 return;
 
         /* Get its name now since this function could
@@ -164,7 +167,7 @@ void trace_boot_ret(struct boot_trace_ret *bt, initcall_t fn)
         unsigned long irq_flags;
         struct trace_array *tr = boot_trace;
 
-        if (!pre_initcalls_finished)
+        if (!tr || !pre_initcalls_finished)
                 return;
 
         sprint_symbol(bt->func, (unsigned long)fn);