1 files changed, 26 insertions, 26 deletions

diff --git a/kernel/trace/trace_sched_wakeup.c b/kernel/trace/trace_sched_wakeup.c
index ad69f105a7c6..26185d727676 100644
--- a/kernel/trace/trace_sched_wakeup.c
+++ b/kernel/trace/trace_sched_wakeup.c
@@ -24,6 +24,7 @@ static int __read_mostly	tracer_enabled;
 
 static struct task_struct       *wakeup_task;
 static int                      wakeup_cpu;
+static int                      wakeup_current_cpu;
 static unsigned                 wakeup_prio = -1;
 static int                      wakeup_rt;
 
@@ -56,33 +57,23 @@ wakeup_tracer_call(unsigned long ip, unsigned long parent_ip)
         resched = ftrace_preempt_disable();
 
         cpu = raw_smp_processor_id();
+        if (cpu != wakeup_current_cpu)
+                goto out_enable;
+
         data = tr->data[cpu];
         disabled = atomic_inc_return(&data->disabled);
         if (unlikely(disabled != 1))
                 goto out;
 
         local_irq_save(flags);
-        __raw_spin_lock(&wakeup_lock);
-
-        if (unlikely(!wakeup_task))
-                goto unlock;
-
-        /*
-         * The task can't disappear because it needs to
-         * wake up first, and we have the wakeup_lock.
-         */
-        if (task_cpu(wakeup_task) != cpu)
-                goto unlock;
 
         trace_function(tr, ip, parent_ip, flags, pc);
 
- unlock:
-        __raw_spin_unlock(&wakeup_lock);
         local_irq_restore(flags);
 
  out:
         atomic_dec(&data->disabled);
-
+ out_enable:
         ftrace_preempt_enable(resched);
 }
 
@@ -107,11 +98,18 @@ static int report_latency(cycle_t delta)
         return 1;
 }
 
+static void probe_wakeup_migrate_task(struct task_struct *task, int cpu)
+{
+        if (task != wakeup_task)
+                return;
+
+        wakeup_current_cpu = cpu;
+}
+
 static void notrace
 probe_wakeup_sched_switch(struct rq *rq, struct task_struct *prev,
         struct task_struct *next)
 {
-        unsigned long latency = 0, t0 = 0, t1 = 0;
         struct trace_array_cpu *data;
         cycle_t T0, T1, delta;
         unsigned long flags;
@@ -157,10 +155,6 @@ probe_wakeup_sched_switch(struct rq *rq, struct task_struct *prev,
         trace_function(wakeup_trace, CALLER_ADDR0, CALLER_ADDR1, flags, pc);
         tracing_sched_switch_trace(wakeup_trace, prev, next, flags, pc);
 
-        /*
-         * usecs conversion is slow so we try to delay the conversion
-         * as long as possible:
-         */
         T0 = data->preempt_timestamp;
         T1 = ftrace_now(cpu);
         delta = T1-T0;
@@ -168,13 +162,10 @@ probe_wakeup_sched_switch(struct rq *rq, struct task_struct *prev,
         if (!report_latency(delta))
                 goto out_unlock;
 
-        latency = nsecs_to_usecs(delta);
-
-        tracing_max_latency = delta;
-        t0 = nsecs_to_usecs(T0);
-        t1 = nsecs_to_usecs(T1);
-
-        update_max_tr(wakeup_trace, wakeup_task, wakeup_cpu);
+        if (likely(!is_tracing_stopped())) {
+                tracing_max_latency = delta;
+                update_max_tr(wakeup_trace, wakeup_task, wakeup_cpu);
+        }
 
 out_unlock:
         __wakeup_reset(wakeup_trace);
@@ -244,6 +235,7 @@ probe_wakeup(struct rq *rq, struct task_struct *p, int success)
         __wakeup_reset(wakeup_trace);
 
         wakeup_cpu = task_cpu(p);
+        wakeup_current_cpu = wakeup_cpu;
         wakeup_prio = p->prio;
 
         wakeup_task = p;
@@ -293,6 +285,13 @@ static void start_wakeup_tracer(struct trace_array *tr)
                 goto fail_deprobe_wake_new;
         }
 
+        ret = register_trace_sched_migrate_task(probe_wakeup_migrate_task);
+        if (ret) {
+                pr_info("wakeup trace: Couldn't activate tracepoint"
+                        " probe to kernel_sched_migrate_task\n");
+                return;
+        }
+
         wakeup_reset(tr);
 
         /*
@@ -325,6 +324,7 @@ static void stop_wakeup_tracer(struct trace_array *tr)
         unregister_trace_sched_switch(probe_wakeup_sched_switch);
         unregister_trace_sched_wakeup_new(probe_wakeup);
         unregister_trace_sched_wakeup(probe_wakeup);
+        unregister_trace_sched_migrate_task(probe_wakeup_migrate_task);
 }
 
 static int __wakeup_tracer_init(struct trace_array *tr)