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From: Ingo Molnar <mingo@elte.hu>
To: Oleg Nesterov <oleg@tv-sign.ru>
Cc: Mike Galbraith <efault@gmx.de>, linux-kernel@vger.kernel.org
Subject: Re: Q: a bogus task_running() check in try_to_wake_up() ?
Date: Tue, 17 Jul 2007 21:05:48 +0200	[thread overview]
Message-ID: <20070717190548.GB26283@elte.hu> (raw)
In-Reply-To: <20070715153914.GA441@tv-sign.ru>


* Oleg Nesterov <oleg@tv-sign.ru> wrote:

> 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().

it's also possible if an arch uses __ARCH_WANT_INTERRUPTS_ON_CTXSW, 
right?

[ btw., we dont have a special "scheduling from the idle thread" check
  in schedule() anymore, it's now in kernel/sched_idletask.c :-) ]

	Ingo

  reply	other threads:[~2007-07-17 19:06 UTC|newest]

Thread overview: 3+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2007-07-15 15:39 Oleg Nesterov
2007-07-17 19:05 ` Ingo Molnar [this message]
2007-07-18 16:35   ` Oleg Nesterov

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