linux-kernel - Re: [PATCH RFC 02/26] task_work: Replace spin_unlock

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Date:   Fri, 30 Jun 2017 13:04:45 +0200
From:   Oleg Nesterov <oleg@...hat.com>
To:     "Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>
Cc:     linux-kernel@...r.kernel.org, netfilter-devel@...r.kernel.org,
        netdev@...r.kernel.org, akpm@...ux-foundation.org,
        mingo@...hat.com, dave@...olabs.net, manfred@...orfullife.com,
        tj@...nel.org, arnd@...db.de, linux-arch@...r.kernel.org,
        will.deacon@....com, peterz@...radead.org,
        stern@...land.harvard.edu, parri.andrea@...il.com,
        torvalds@...ux-foundation.org
Subject: Re: [PATCH RFC 02/26] task_work: Replace spin_unlock_wait() with
 lock/unlock pair

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.