ftrace: clean up enable logic for sched_switch

Unify sched_switch and sched_wakeup's action to following logic:
Do record_cmdline when start_cmdline_record() is called.
Start tracing events when the tracer is started.

Signed-off-by: Zhao Lei <zhaolei@cn.fujitsu.com>
LKML-Reference: <49D1C596.5050203@cn.fujitsu.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

diff --git a/kernel/trace/trace_sched_switch.c b/kernel/trace/trace_sched_switch.c
index 9117cea6f1ae78f17f2be7fc9894aa9b0abe2075..9d8cccdfaa06c42e8f50729e7605f9a8b9f9b5f1 100644 (file)
--- a/kernel/trace/trace_sched_switch.c
+++ b/kernel/trace/trace_sched_switch.c
@@ -29,13 +29,13 @@ probe_sched_switch(struct rq *__rq, struct task_struct *prev,
        int cpu;
        int pc;
 
-       if (!sched_ref || sched_stopped)
+       if (unlikely(!sched_ref))
                return;
 
        tracing_record_cmdline(prev);
        tracing_record_cmdline(next);
 
-       if (!tracer_enabled)
+       if (!tracer_enabled || sched_stopped)
                return;
 
        pc = preempt_count();
@@ -56,15 +56,15 @@ probe_sched_wakeup(struct rq *__rq, struct task_struct *wakee, int success)
        unsigned long flags;
        int cpu, pc;
 
-       if (!likely(tracer_enabled))
+       if (unlikely(!sched_ref))
                return;
 
-       pc = preempt_count();
        tracing_record_cmdline(current);
 
-       if (sched_stopped)
+       if (!tracer_enabled || sched_stopped)
                return;
 
+       pc = preempt_count();
        local_irq_save(flags);
        cpu = raw_smp_processor_id();
        data = ctx_trace->data[cpu];