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

Steven Rostedt
2007-09-28T23:05:45Z

--
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.

> > + * 2. Outermost rcu_read_unlock() for blocked RCU read-side critical section.
> > + *
>
> Event #3. is missing?

I guess Paul needs to answer that one ;-)

-- Steve