From mboxrd@z Thu Jan  1 00:00:00 1970
From: Oleg Nesterov <oleg@redhat.com>
Subject: Re: [PATCH RFC 02/26] task_work: Replace spin_unlock_wait() with
 lock/unlock pair
Date: Fri, 30 Jun 2017 13:04:45 +0200
Message-ID: <20170630110445.GA5123@redhat.com>
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To: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
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On 06/29, Paul E. McKenney wrote:
>
> --- a/kernel/task_work.c
> +++ b/kernel/task_work.c
> @@ -109,7 +109,8 @@ void task_work_run(void)
>  		 * the first entry == work, cmpxchg(task_works) should
>  		 * fail, but it can play with *work and other entries.
>  		 */
> -		raw_spin_unlock_wait(&task->pi_lock);
> +		raw_spin_lock(&task->pi_lock);
> +		raw_spin_unlock(&task->pi_lock);

Well, bit the you need spin_lock_irq(). And this is one of the reasons
why I personally think unlock_wait have some sense...

Oleg.