ftrace: fix wakeups

Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

1 files changed, 18 insertions, 0 deletions

diff --git a/kernel/sched.c b/kernel/sched.c
index 673b588b713..9ca4a2e6a23 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -642,6 +642,24 @@ static inline void update_rq_clock(struct rq *rq)
 # define const_debug static const
 #endif
 
+/**
+ * runqueue_is_locked
+ *
+ * Returns true if the current cpu runqueue is locked.
+ * This interface allows printk to be called with the runqueue lock
+ * held and know whether or not it is OK to wake up the klogd.
+ */
+int runqueue_is_locked(void)
+{
+	int cpu = get_cpu();
+	struct rq *rq = cpu_rq(cpu);
+	int ret;
+
+	ret = spin_is_locked(&rq->lock);
+	put_cpu();
+	return ret;
+}
+
 /*
  * Debugging: various feature bits
  */