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SubjectRe: [PATCH tip/core/rcu 04/18] rcu: Use single-stage IPI algorithm for RCU expedited grace period
On Wed, Oct 07, 2015 at 03:24:54PM +0200, Peter Zijlstra wrote:
> On Tue, Oct 06, 2015 at 09:29:23AM -0700, Paul E. McKenney wrote:
> > @@ -3494,19 +3483,21 @@ static int sync_rcu_preempt_exp_done(struct rcu_node *rnp)
> > * recursively up the tree. (Calm down, calm down, we do the recursion
> > * iteratively!)
> > *
> > - * Caller must hold the root rcu_node's exp_funnel_mutex.
> > + * Caller must hold the root rcu_node's exp_funnel_mutex and the
> > + * specified rcu_node structure's ->lock.
> > */
> > -static void __maybe_unused rcu_report_exp_rnp(struct rcu_state *rsp,
> > - struct rcu_node *rnp, bool wake)
> > +static void __rcu_report_exp_rnp(struct rcu_state *rsp, struct rcu_node *rnp,
> > + bool wake, unsigned long flags)
> > + __releases(rnp->lock)
> > {
> > - unsigned long flags;
> > unsigned long mask;
> >
> > - raw_spin_lock_irqsave(&rnp->lock, flags);
> > - smp_mb__after_unlock_lock();
>
> lockdep_assert_held(&rnp->lock);
>
> > +/*
> > + * Report expedited quiescent state for specified node. This is a
> > + * lock-acquisition wrapper function for __rcu_report_exp_rnp().
> > + *
> > + * Caller must hold the root rcu_node's exp_funnel_mutex.
> > + */
> > +static void __maybe_unused rcu_report_exp_rnp(struct rcu_state *rsp,
> > + struct rcu_node *rnp, bool wake)
> > +{
> > + unsigned long flags;
>
> lockdep_assert_held(&rcu_get_root(rsp)->exp_funnel_mutex);
>
> > +
> > + raw_spin_lock_irqsave(&rnp->lock, flags);
> > + smp_mb__after_unlock_lock();
> > + __rcu_report_exp_rnp(rsp, rnp, wake, flags);
> > +}
>
>
> Etc.. these are much harder to ignore than comments.

Good point! I probably should do the same for interrupt disabling.

Thanx, Paul



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