On Wed, Oct 28, 2020 at 12:07:12PM +0100, Peter Zijlstra wrote:
> While the traditional irq_work relies on the ability to self-IPI, it
> makes sense to provide an unconditional irq_work_queue_remote()
> interface.
We may need a reason as well here.
> --- a/kernel/rcu/tree.c
> +++ b/kernel/rcu/tree.c
> @@ -1308,13 +1308,14 @@ static int rcu_implicit_dynticks_qs(stru
> resched_cpu(rdp->cpu);
> WRITE_ONCE(rdp->last_fqs_resched, jiffies);
> }
> - if (IS_ENABLED(CONFIG_IRQ_WORK) &&
> - !rdp->rcu_iw_pending && rdp->rcu_iw_gp_seq != rnp->gp_seq &&
> +#ifdef CONFIG_IRQ_WORK
> + if (!rdp->rcu_iw_pending && rdp->rcu_iw_gp_seq != rnp->gp_seq &&
If it's unconditional on SMP, I expect it to be unconditional on rcutree.
Also this chunk seems unrelated to this patch.
> (rnp->ffmask & rdp->grpmask)) {
> rdp->rcu_iw_pending = true;
> rdp->rcu_iw_gp_seq = rnp->gp_seq;
> irq_work_queue_on(&rdp->rcu_iw, rdp->cpu);
> }
> +#endif
> }
>
> return 0;
>
>
