trace: let boot trace be chosen by command line
Now that we have a working ftrace=<tracer> function, make the boot
tracer get activated by it. This way we can turn it on or off without
recompiling the kernel, as well as keeping the selftests on. The
selftests are disabled whenever a default tracer starts running.
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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 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 @@
int cpu;
boot_trace = tr;
+ if (!tr)
+ return 0;
+
for_each_cpu(cpu, cpu_possible_mask)
tracing_reset(tr, cpu);
@@ -132,7 +135,7 @@
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 @@
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);