[PATCH v2] blk-mq: use a housekeeping CPU for passthrough requests on isolated hctxs

[Sebastian Andrzej Siewior]

On 2026-11-04 08:17:03 [+0100], Christoph Hellwig wrote:
> On Tue, Nov 03, 2026 at 05:37:48PM +0100, Sebastian Andrzej Siewior wrote:
> > What about
> > 	guard(rcu);
> > 	for_each_cpu_and(cpu, cpu_online_mask, housekeeping_cpumask(HK_TYPE_MANAGED_IRQ)) {
> > 		if (!cpu_is_isolated(cpu)
> > 			break;
> > 	}
> > 
> > this ends up with one less function call ;)
> 
> Please avoid this completely unreadable and unaditable guard crap.

If you/ block prefers to avoid guard() then fine. I usually get punched
the other way around.

> How is anyone supposed to understand that above mess?

I can show you code where you start crying. Anyway. My main selling
point was for_each_cpu_and().

Sebastian