On Tue, Oct 06, 2015 at 09:29:21AM -0700, Paul E. McKenney wrote:
> +static void __maybe_unused rcu_report_exp_rnp(struct rcu_state *rsp,
> + struct rcu_node *rnp, bool wake)
> +{
> + unsigned long flags;
> + unsigned long mask;
> +
> + raw_spin_lock_irqsave(&rnp->lock, flags);
Normally we require a comment with barriers, explaining the order and
the pairing etc.. :-)
> + smp_mb__after_unlock_lock();
> + for (;;) {
> + if (!sync_rcu_preempt_exp_done(rnp)) {
> + raw_spin_unlock_irqrestore(&rnp->lock, flags);
> + break;
> + }
> + if (rnp->parent == NULL) {
> + raw_spin_unlock_irqrestore(&rnp->lock, flags);
> + if (wake) {
> + smp_mb(); /* EGP done before wake_up(). */
> + wake_up(&rsp->expedited_wq);
> + }
> + break;
> + }
> + mask = rnp->grpmask;
> + raw_spin_unlock(&rnp->lock); /* irqs remain disabled */
> + rnp = rnp->parent;
> + raw_spin_lock(&rnp->lock); /* irqs already disabled */
> + smp_mb__after_unlock_lock();
> + rnp->expmask &= ~mask;
> + }
> +}
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