[PATCH -tip] sched: fix using uninilialzed rq in task_delta_exec()

[Hiroshi Shimamoto <h-shimamoto@ct.jp.nec.com>]

From: Hiroshi Shimamoto <h-shimamoto@ct.jp.nec.com>

compiler warnings;

  CC      kernel/sched.o
kernel/sched.c: In function 'task_delta_exec':
kernel/sched.c:4055: warning: unused variable 'flags'
kernel/sched.c:4054: warning: 'rq' is used uninitialized in this function

calling task_delta_exec() may cause unexpected pointer access.

Signed-off-by: Hiroshi Shimamoto <h-shimamoto@ct.jp.nec.com>
---
 kernel/sched.c |    2 ++
 1 files changed, 2 insertions(+), 0 deletions(-)

diff --git a/kernel/sched.c b/kernel/sched.c
index 30b73fc..b6c0dd8 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -4055,6 +4055,7 @@ unsigned long long task_delta_exec(struct task_struct *p)
 	unsigned long flags;
 	u64 ns = 0;
 
+	rq = task_rq_lock(p, &flags);
 	if (task_current(rq, p)) {
 		u64 delta_exec;
 
@@ -4063,6 +4064,7 @@ unsigned long long task_delta_exec(struct task_struct *p)
 		if ((s64)delta_exec > 0)
 			ns = delta_exec;
 	}
+	task_rq_unlock(rq, &flags);
 
 	return ns;
 }
-- 
1.5.6