linux-kernel - Q: a bogus task_running() check in try_to_wake

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Date:	Sun, 15 Jul 2007 19:39:14 +0400
From:	Oleg Nesterov <oleg@...sign.ru>
To:	Ingo Molnar <mingo@...e.hu>, Mike Galbraith <efault@....de>
Cc:	linux-kernel@...r.kernel.org
Subject: Q: a bogus task_running() check in try_to_wake_up() ?

try_to_wake_up:

	if (p->se.on_rq)
		goto out_running;

	...

	if (unlikely(task_running(rq, p)))
		goto out_activate;

How it possible that rq->curr has on_rq == 0 ?

AFAICS, this can only happen if this task is rq->idle. But idle threads
should not sleep, we have a special "scheduling from the idle thread!"
check in schedule().

Thanks in advance,

Oleg.

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