Re: Why can't I set the priority of softirq-hrt? (Re: 2.6.17-rt1)

[Thomas Gleixner <tglx@linutronix.de>]

On Thu, 2006-06-22 at 09:45 -0400, Steven Rostedt wrote:
> > + * Recheck the pi chain, in case we got a priority setting
> > + *
> > + * Called from sched_setscheduler
> > + */
> > +void rt_mutex_adjust_pi(struct task_struct *task)
> > +{
> > +	struct rt_mutex_waiter *waiter = task->pi_blocked_on;
> > +	unsigned long flags;
> 
> Hmm, what if the process wakes up here and unblocks?  Since waiter is
> on the stack, you could have a nasty race here.

Thats fixed already. Moved into te pi_lock section

> > +
> > +	spin_lock_irqsave(&task->pi_lock, flags);
> > +
> > +	if (!waiter || waiter->list_entry.prio == task->prio) {
> > +		spin_unlock_irqrestore(&task->pi_lock, flags);
> > +		return;
> > +	}
> > +
> > +	get_task_struct(task);
> > +	spin_unlock_irqrestore(&task->pi_lock, flags);
> > +
> > +	rt_mutex_adjust_prio_chain(task, 0, NULL, NULL, task);
> 
> Nasty nasty nasty!

What's nasty ? 

	tglx


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