3 files changed, 11 insertions, 12 deletions
diff --git a/kernel/trace/Kconfig b/kernel/trace/Kconfig
index dde1d46..28f2644 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 2c720c7..40edef4 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 0e94b3d..1f07895 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);