Re: [PATCH RFC 6/9] RCU priority boosting for preemptible RCU

Paul E. McKenney
2007-09-30T03:11:48Z

On Fri, Sep 28, 2007 at 07:05:14PM -0400, Steven Rostedt wrote:
>
>
> --
> On Fri, 28 Sep 2007, Gautham R Shenoy wrote:
>
> > >
> > > +#ifdef CONFIG_PREEMPT_RCU_BOOST
> > > +/*
> > > + * Task state with respect to being RCU-boosted. This state is changed
> > > + * by the task itself in response to the following three events:
> > ^^^
> > > + * 1. Preemption (or block on lock) while in RCU read-side critical section.
> >
> > I am wondering, can a task block on a lock while in RCU read-side
> > critical section?
>
> I think this may be specific to the -rt patch. In the -rt patch,
> spin_locks turn into mutexes, and therefor can block a read-side critical
> section.

Yep! I do need to fix the comment.

> > > + * 2. Outermost rcu_read_unlock() for blocked RCU read-side critical section.
> > > + *
> >
> > Event #3. is missing?
>
> I guess Paul needs to answer that one ;-)

An older version had three, the new one has two, and I forgot to s/three/two/.

Thanx, Paul