[PATCH] tracing/ftrace: use preempt_enable_no_resched_notrace in ring_buffer_time_stamp()

[Frederic Weisbecker <fweisbec@gmail.com>]

Impact: prevent a trace recursion

After some tests with function graph tracer under x86-32, I saw some recursions
caused by ring_buffer_time_stamp() that calls preempt_enable_no_notrace() which
calls preempt_schedule() which is traced itself.

This patch re-enables preemption without rescheduling.

Cc: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
---
 kernel/trace/ring_buffer.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c
index 822fcd4..a775e46 100644
--- a/kernel/trace/ring_buffer.c
+++ b/kernel/trace/ring_buffer.c
@@ -109,7 +109,7 @@ u64 ring_buffer_time_stamp(int cpu)
 	preempt_disable_notrace();
 	/* shift to debug/test normalization and TIME_EXTENTS */
 	time = sched_clock() << DEBUG_SHIFT;
-	preempt_enable_notrace();
+	preempt_enable_no_resched_notrace();
 
 	return time;
 }
-- 
1.6.0.4