ftrace: prevent recursion

Impact: prevent unnecessary stack recursion

if the resched flag was set before we entered, then don't reschedule.

Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com>
Acked-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c
index f780e95..668bbb5 100644
--- a/kernel/trace/ring_buffer.c
+++ b/kernel/trace/ring_buffer.c
@@ -1215,7 +1215,7 @@
 
  out:
 	if (resched)
-		preempt_enable_notrace();
+		preempt_enable_no_resched_notrace();
 	else
 		preempt_enable_notrace();
 	return NULL;