migration_call(CPU_DEAD): use spin_lock_irq() instead of task_rq_lock()

Change migration_call(CPU_DEAD) to use direct spin_lock_irq() instead of
task_rq_lock(rq->idle), rq->idle can't change its task_rq().

This makes the code a bit more symmetrical with migrate_dead_tasks()'s path
which uses spin_lock_irq/spin_unlock_irq.

Signed-off-by: Oleg Nesterov <[email protected]>
Cc: Cliff Wickman <[email protected]>
Cc: Gautham R Shenoy <[email protected]>
Cc: Ingo Molnar <[email protected]>
Cc: Srivatsa Vaddagiri <[email protected]>
Cc: Akinobu Mita <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

1 files changed, 2 insertions, 2 deletions

diff --git a/kernel/sched.c b/kernel/sched.c
index c747bc9f3c24..c4889abc00b6 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -5457,14 +5457,14 @@ migration_call(struct notifier_block *nfb, unsigned long action, void *hcpu)
 		kthread_stop(rq->migration_thread);
 		rq->migration_thread = NULL;
 		/* Idle task back to normal (off runqueue, low prio) */
-		rq = task_rq_lock(rq->idle, &flags);
+		spin_lock_irq(&rq->lock);
 		update_rq_clock(rq);
 		deactivate_task(rq, rq->idle, 0);
 		rq->idle->static_prio = MAX_PRIO;
 		__setscheduler(rq, rq->idle, SCHED_NORMAL, 0);
 		rq->idle->sched_class = &idle_sched_class;
 		migrate_dead_tasks(cpu);
-		task_rq_unlock(rq, &flags);
+		spin_unlock_irq(&rq->lock);
 		migrate_nr_uninterruptible(rq);
 		BUG_ON(rq->nr_running != 0);