[PATCH v3 12/45] migration: Use raw_spin_lock/unlock since interrupts are already disabled

["Srivatsa S. Bhat" <srivatsa.bhat@linux.vnet.ibm.com>]

We need not use the raw_spin_lock_irqsave/restore primitives because
all CPU_DYING notifiers run with interrupts disabled. So just use
raw_spin_lock/unlock.

Cc: Ingo Molnar <mingo@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Srivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com>
---

 kernel/sched/core.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 9d870bf..ad8a554 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -4675,14 +4675,14 @@ migration_call(struct notifier_block *nfb, unsigned long action, void *hcpu)
 	case CPU_DYING:
 		sched_ttwu_pending();
 		/* Update our root-domain */
-		raw_spin_lock_irqsave(&rq->lock, flags);
+		raw_spin_lock(&rq->lock); /* IRQs already disabled */
 		if (rq->rd) {
 			BUG_ON(!cpumask_test_cpu(cpu, rq->rd->span));
 			set_rq_offline(rq);
 		}
 		migrate_tasks(cpu);
 		BUG_ON(rq->nr_running != 1); /* the migration thread */
-		raw_spin_unlock_irqrestore(&rq->lock, flags);
+		raw_spin_unlock(&rq->lock);
 		break;
 
 	case CPU_DEAD: