Re: [patch V3 7/7] rtmutex: Avoid pointless requeueing in the deadlock detection chain walk

[Thomas Gleixner]

On Tue, 10 Jun 2014, Steven Rostedt wrote:

> On Tue, 10 Jun 2014 19:41:39 +0200 (CEST)
> Thomas Gleixner <tglx@xxxxxxxxxxxxx> wrote:
> 
>  
> > > On the loop back around, have something like:
> > > 
> > > 	if (top_waiter) {
> > > 		if (!task_has_pi_waiters(task))
> > > 			goto out_unlock_pi;
> > 
> > 	The task has at least one pi waiter.
> >  
> > > 		if (!requeue &&
> > > 		    top_waiter != task_top_pi_waiter(task)) {
> > > 			if (!detect_deadlock)
> > > 				goto out_unlock_pi;
> > > 			else
> > > 				requeue = false;
> > > 		}
> > 
> > 	Errm? if requeue is off we are in deadlock detection chainwalk
> > 	mode. So all we care about is whether task is blocked on
> > 	next_lock or not.
> 
> Actually that was a typo on my part. That should have been:
> 
> 	if (requeue &&
> 		...
> 
> As we don't need to read the task_top_pi_waiter() again.

     if (requeue ...

is completely pointless as the code you were talking about is in the

   if (!requeue) {

branch. So what?

Thanks,

	tglx
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