sched: Remove rcu_read_lock/unlock() from select_idle_sibling()

select_idle_sibling() is called from select_task_rq_fair(), which
already has the RCU read lock held.
Signed-off-by: NNikunj A. Dadhania <nikunj@linux.vnet.ibm.com>
Signed-off-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/20120217030409.11748.12491.stgit@abhimanyuSigned-off-by: NIngo Molnar <mingo@elte.hu>

kernel/sched/fair.c

@@ -2670,8 +2670,6 @@ static int select_idle_sibling(struct task_struct *p, int target)
 	/*
 	 * Otherwise, iterate the domains and find an elegible idle cpu.
 	 */
-	rcu_read_lock();
-
 	sd = rcu_dereference(per_cpu(sd_llc, target));
 	for_each_lower_domain(sd) {
 		sg = sd->groups;
@@ -2693,8 +2691,6 @@ static int select_idle_sibling(struct task_struct *p, int target)
 		} while (sg != sd->groups);
 	}
 done:
-	rcu_read_unlock();
-
 	return target;
 }