linux-kernel - Re: [PATCH] wait_task_inactive: don't consider task->nivcsw

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Date:	Sun, 27 Jul 2008 12:55:13 -0700 (PDT)
From:	Roland McGrath <roland@...hat.com>
To:	Oleg Nesterov <oleg@...sign.ru>
Cc:	akpm@...ux-foundation.org, torvalds@...ux-foundation.org,
	mingo@...e.hu, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] wait_task_inactive: don't consider task->nivcsw

> If wait_task_inactive() returns success the task was deactivated.
> In that case schedule() always increments ->nvcsw which alone can
> be used as a "generation counter".

Thanks, that looks fine to me.

> Q: perhaps it is better to do "ncsw = (p->nvcsw << 1) | 1" ? This
> decreases the possibility of "was it unscheduled" false positive
> when ->nvcsw == 0.

That makes sense.


Thanks,
Roland
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