[PATCH] rcutorture: Use __set_current_state() set task state in rcu_nocb_toggle()

[PATCH] rcutorture: Use __set_current_state() set task state in rcu_nocb_toggle()

[Zqiang]

In the rcu_nocb_toggle(), the schedule_hrtimeout() is called after the
state assignment with no condition check. the release-acquire pair from
raw_spin_unlock/lock(&cpu_base->lock), guarantee that task->__state is
visible to the hrtimer callback:

              CPU0                                                     CPU1
__set_current_state(TASK_INTERRUPTIBLE)
->WRITE_ONCE(task->__state, TASK_INTERRUPTIBLE)
schedule_hrtimeout
->hrtimer_sleeper_start_expires()
  ->raw_spin_lock_irqsave(&cpu_base->lock)
    ....
  ->raw_spin_unlock_irqrestore(&cpu_base->lock)

								hard-irq:
							raw_spin_lock_irqsave(&cpu_base->lock)
							__hrtimer_run_queues
							->__run_hrtimer
							  ->raw_spin_unlock_irqrestore(&cpu_base->lock)
							  ->fn(timer)
							    ->hrtimer_wakeup
							      ->wake_up_process
								->try_to_wake_up
								  ->READ task->__state

This commit therefore use the __set_current_state() to replace the
set_current_state() in rcu_nocb_toggle().

Signed-off-by: Zqiang <qiang.zhang@linux.dev>
---
 kernel/rcu/rcutorture.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/kernel/rcu/rcutorture.c b/kernel/rcu/rcutorture.c
index b1bab59efde5..a0e6901e0f90 100644
--- a/kernel/rcu/rcutorture.c
+++ b/kernel/rcu/rcutorture.c
@@ -2947,7 +2947,7 @@ static int rcu_nocb_toggle(void *arg)
 			atomic_long_inc(&n_nocb_deoffload);
 		}
 		toggle_delay = torture_random(&rand) % toggle_fuzz + toggle_interval;
-		set_current_state(TASK_INTERRUPTIBLE);
+		__set_current_state(TASK_INTERRUPTIBLE);
 		schedule_hrtimeout(&toggle_delay, HRTIMER_MODE_REL);
 		if (stutter_wait("rcu_nocb_toggle"))
 			sched_set_normal(current, oldnice);
-- 
2.17.1