From: Con Kolivas <kernel@kolivas.org>
To: liyu@ccoss.com.cn
Subject: Re: [Question]How to restrict some kind of task?
Date: Thu, 17 Nov 2005 20:57:32 +1100
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On Thu, 17 Nov 2005 17:20, liyu wrote:
> I fixed it. we should insert code start of enqueue_task():
>
> static void enqueue_task(struct task_struct *p, prio_array_t *array)
> {
>              unsigned long flags;
>
>              spin_lock_irqsave(&(task_rq(p)->keep_lock), flags);
>              if (p->flags & PF_KEEPOVER) {
>                      list_del(&p->run_list);
>                      p->state = TASK_RUNNING;
>                      p->flags &= ~PF_KEEPOVER;
>              }
>              spin_unlock_irqrestore(&(task_rq(p)->keep_lock), flags);
>
> ....
> }
> However, this patch still have problem, it may lock entire system.
>
> I am trying to catch this bug~.

The obvious bug is that there are places that expect a task to be added to the 
run list after it has called enqueue_task and you've broken that expectation. 
The locking in the rest of your patch did not look too robust, but I don't 
have time to review it sorry.

Cheers,
Con
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